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The objective of this study was to evaluate the lipid peroxidation and the susceptibility of erythrocytes to in vitro peroxidation as indicators of oxidative damage in erythrocytes and their roles in the pathogenesis of anemia during experimental Trypanosoma evansi infection in cats. Animals were divided into two groups: control and infected with T. evansi. Seven cats were infected with 10(8) trypomastigotes each, and parasitemia was estimated daily for 49 days by microscopic examination of smears. Hematological and biochemical parameters were evaluated for monitoring of the disease. Plasma lipid peroxidation (Thiobarbituric Acid Reactive Substances (TBARS)) and the susceptibility of erythrocytes to in vitro peroxidation were evaluated. Blood samples for analysis were collected at days 21 and 49 post-inoculation. TBARS level, indicated by MDA concentration, was higher in the infected group than in the control group in both analyzed periods, as well as the in vitro erythrocyte peroxidation (P < 0.001). The infected cats had variable degrees of regenerative anemia, which could be explained by the damage in erythrocyte membrane caused by lipid peroxidation.

Objective: In natural populations, infection and condition may act synergistically to trigger a vicious circle: poor condition predisposes to host infections, which further reduce condition, and so on. If this vicious circle originates from a reduced resistance to infection, it will not only result in greater proneness to becoming infected of those that are in poorer condition, but it may also cause infections of higher intensity. Here, we investigate the temporal relationship between host condition and intensity of infection by a specific pathogen using as a system the dynamics of the protozoan Trypanosoma microti in field vole (Microtus agrestis) populations., Methods and Results: With two years of longitudinal data from three monthly-sampled populations, we evaluated if individuals acquiring a high intensity of infection previously had lower haematological indicators of condition (red blood cells [RBCs] and lymphocyte counts) than those that acquired lower infection intensities. Also, the association of these indicators with past and present trypanosome blood levels was investigated. The individuals that developed high levels of parasitaemia were those that previously had low lymphocyte counts. Greater intensity of infection corresponded with lower RBCs only in low to moderate weight females, and no effect of intensity of infection on lymphocyte counts was observed. However, delayed effects of high trypanosome intensity were seen on both RBCs and lymphocytes., Conclusions: The vicious circle may also result in high infection intensity: individuals in poor condition are not only more likely to become infected by one pathogen; they may also be the most important source of infection for that and for other pathogens, and thus key protagonists for parasite dynamics.

Simple demographic and infectious disease models of buffaloes and other domestic hosts for animal trypanosomosis (surra) caused by Trypanosoma evansi were developed. The animal models contained deterministic and stochastic elements and were linked to simulate the benefit of control regimes for surra in village domestic animal populations in Mindanao, Philippines. The impact of the disease on host fertility and mortality were key factors in determining the economic losses and net-benefit from the control regimes. If using a high (99%) efficacy drug in surra-moderate to high risk areas, then treating all animals twice each year yielded low prevalence in 2 years; targeted treatment of clinically sick animals, constantly monitored (monthly), required 75% fewer treatments but took longer to reach a low prevalence than treating all animals twice each year. At high drug efficacy both of these treatment strategies increased the benefit over untreated animals by 81%. If drug efficacy declined then the benefit obtained from twice yearly treatment of all animals declined rapidly compared with regular monitoring and targeting treatment to clinically sick animals. The current control regimen applied in the Philippines of annual sero-testing for surra and only treating sero-positive animals provided the lowest net-benefit of all the control options simulated and would not be regarded as effective control. The total net-benefit from effective surra control for a typical village in a moderate/high risk area was 7.9 million pesos per annum (US $158,000). The value added to buffaloes, cattle, horses, goats/sheep and pigs as a result of this control was US $88, $84, $151, $7, $114 per animal/year, respectively.

Epigenetic regulation is important in many facets of eukaryotic biology. Recent work has suggested that the basic mechanisms underlying epigenetic regulation extend to eukaryotic parasites. The identification of post-translational histone modifications and chromatin-modifying enzymes is beginning to reveal both common and novel functions for chromatin in these parasites. In this Review, we compare the role of epigenetics in African trypanosomes and humans in several biological processes. We discuss how the study of trypanosome chromatin might help us to better understand the evolution of epigenetic processes.

Trypanosomosis (surra) caused by Trypanosoma evansi is quite common among horses where the parasite is endemic. In the present study, T. evansi was isolated from an infected horse and maintained by subinoculation in Swiss albino mice. At the peak of parasitemia (5 x 10(6) parasites per ml of blood), 0.25 ml of the tail blood from infected mice was inoculated intraperitoneally and subcutaneously to 2 groups of adult pigeons and 2 groups of pigeon nestlings. Four days after inoculation, the trypanosomes occurred in the peripheral circulation of pigeon nestlings, but no parasitemia was observed in adult pigeons. The body temperatures of infected nestlings increased to 104 F, whereas uninfected controls remained steady at 102 F; thus, elevated temperatures coincided with parasite presence in the peripheral circulation. A decrease in hemoglobin concentration of blood also was observed in infected nestlings. On microscopic examination, increases in length and breadth of trypomastigotes and vigorous flagellar movement of the parasites were observed. The virulence and pathogenicity of the parasites after adaptation to nestlings remained unchanged for albino mice as proved by the death of all subinoculated mice. Furthermore, polymerase chain reaction studies confirmed that the genomic DNA of trypanosomes in pigeon blood was the same as that of T. evansi. This is the first report of the establishment of T. evansi infection in pigeon nestlings.

Animal trypanosomosis is one of the most severe constraints to agricultural development in sub-Saharan Africa and is also an important disease of livestock in Latin America and Asia. The causative agents are various species of protozoan parasites belonging to the genus Trypanosoma, among which T. congolense and T. evansi are the major pathogenic species. The extracellular position of trypanosomes obliges us to consider both the parasite and its excreted/secreted factors in the course of the physiopathologic process. The advent of proteomics led us to propose a comparative approach of the proteome (i.e., the whole parasite content) and the secretome (i.e., naturally excreted/secreted molecules) of T. congolense and T. evansi with particular attention to common and specific molecules between strains of differing virulence and pathogenicity. The molecular identification of differentially expressed trypanosome molecules correlated with either the virulence process or the pathogenicity will provide new potential molecular targets for improved field diagnosis and chemotherapy of animal trypanosomosis.

Humans express a unique subset of high-density lipoproteins (HDLs) called trypanosome lytic factors (TLFs) that kill many Trypanosoma parasite species. The proteins apolipoprotein (apo) A-I, apoL-I, and haptoglobin-related protein, which are involved in TLF structure and function, were expressed through the introduction of transgenes in mice to explore their physiological roles in vivo. Transgenic expression of human apolipoprotein L-I alone conferred trypanolytic activity in vivo. Coexpression of human apolipoprotein A-I and haptoglobin-related protein (Hpr) had an effect on the integration of apolipoprotein L-I into HDL, and both proteins were required to increase the specific activity of TLF, which was measurable in vitro. Unexpectedly, truncated apolipoprotein L-I devoid of the serum resistance gene interacting domain, which was previously shown to kill human infective trypanosomes, was not trypanolytic in transgenic mice despite being coexpressed with human apolipoprotein A-I and Hpr and incorporated into HDLs. We conclude that all three human apolipoproteins act cooperatively to achieve maximal killing capacity and that truncated apolipoprotein L-I does not function in transgenic animals.

African trypanosomiasis is a severe parasitic disease affecting both man and livestock. It is crucial to expand our fundamental knowledge of the intimate interactions between trypanosomes and their vertebrate hosts in order to develop new and efficient control strategies. The mouse model of trypanosomiasis is the most popular for research purposes because of all the logistic advantages of using this species. Studies of any aspect of trypanosomiases in the mouse systematically require the quantification of some phenotypic traits which translate its degree of resistance/susceptibility to the disease, as blood cell counts. The present study presents a methodological approach combining everyday microsampling of tail blood and its analysis by flow cytometry. The technical options and conditions permitting a fast, reliable and reproducible daily quantification of erythrocyte, reticulocyte, leucocyte and trypanosome counts in the inoculated mouse were established. The protocol proposed allows the multiplication of blood samplings without being exposed to the time-consuming constraint of visual countings, without causing iatrogenic blood cell alterations in the mouse and without requiring specific anti-trypanosome antibodies.

Parasites of wild primates are important for conservation biology and human health due to their high potential to infect humans. In the Amazon region, non-human primates are commonly infected by Trypanosoma cruzi and T. rangeli, which are also infective to man and several mammals. This is the first survey of trypanosomiasis in a critically endangered species of tamarin, Saguinus bicolor (Callitrichidae), from the Brazilian Amazon Rainforest. Of the 96 free-ranging specimens of S. bicolor examined 45 (46.8%) yielded blood smears positive for trypanosomes. T. rangeli was detected in blood smears of 38 monkeys (39.6%) whereas T. cruzi was never detected. Seven animals (7.3%) presented trypanosomes of the subgenus Megatrypanum. Hemocultures detected 84 positive tamarins (87.5%). Seventy-two of 84 (85.7%) were morphologically diagnosed as T. rangeli and 3 (3.1%) as T. cruzi. Nine tamarins (9.4%) yielded mixed cultures of these two species, which after successive passages generated six cultures exclusively of T. cruzi and two of T. rangeli, with only one culture remaining mixed. Of the 72 cultures positive for T. rangeli, 62 remained as established cultures and were genotyped: 8 were assigned to phylogenetic lineage A (12.9%) and 54 to lineage B (87.1%). Ten established cultures of T. cruzi were genotyped as TCI lineage (100%). Transmission of both trypanosome species, their potential risk to this endangered species and the role of wild primates as reservoirs for trypanosomes infective to humans are discussed.

A study was undertaken in July 2005 to investigate an acute haemorrhagic syndrome that caused cattle mortality starting March 2005 in Mifumi, Senda, Kainja and Nyagoke villages of Tororo district in Uganda; areas dominantly infested with Glossina fuscipes fuscipes with scanty G. pallidipes. Four hundred and one (401) cattle belonging to 158 farmers were randomly sampled from a population of 549 and screened using a combination of Haematocrit Centrifugation Technique (HCT) and Buffy Coat Technique (BCT) for trypanosomosis. Of which 49 (12.2%) had trypanosome infection. Clinical cases manifested bleeding through the ears, severe weight loss, anaemia, weakness and enlarged lymph nodes prior to death. Out of an original population of 844 cattle 295 (35%) had died. The prevalence of bovine trypanosomosis in herds experiencing mortality (21.5%) was significantly higher than in those without mortality (2.6%) (chi(2)=33.4, P<0.001). Herd size, number of draught oxen and lactating cows in a given herd significantly influenced the risk of mortality (P<0.001). Males had a significantly higher prevalence of trypanosomosis (17.8%) than females (9.5%) (chi(2)=5.58, P<0.05) and significantly lower mean packed cell volume (PCV) (23.7%) than females (25.4%) (P<0.05). Older calves (7-12 months), yearlings (13-24 months) and adults (>24 months) with prevalences of 11.1%, 15.4% and 11.8%, respectively, were the most affected age categories. Trypanosome-infected cattle had a significantly lower mean PCV (17.9%) than non-infected ones (25.8%) (P<0.001), and a significantly higher proportion of anaemic animals (81.6%) than non-infected ones (37.2%) (chi(2)=34.6, P<0.001). Trypanosoma vivax was the dominant trypanosome species, constituting 82% of trypanosome infections. This work has provided further evidence on the importance of T. vivax-induced acute haemorrhagic syndrome in livestock trypanosomosis.

In our laboratory, we have developed a model of vaccination in mice with Trypanosoma rangeli, a non-pathogenic parasite that shares many antigens with Trypanosoma cruzi. The vaccinated mice were protected against infection with virulent T. cruzi. The goal of the present work was to study the protective activity of strains of T. rangeli of different origin, with the aim of analysing whether this protective capacity is a common feature of T. rangeli. BALB/c mice were vaccinated with live or fixed epimastigotes of two T. rangeli strains, Choachi and SC-58. Vaccinated (VM) and control mice (CM) were infected with virulent T. cruzi, Tulahuen strain. The results showed that the levels of parasitemia of VM, vaccinated with the two strains of T. rangeli were significantly lower than those developed in CM. The survival rate of VM was higher than that CM. Histological studies revealed many amastigote nests and severe inflammatory infiltrates in the heart and skeletal muscles of CM, whereas in the VM only moderate lymphomonocytic infiltrates were detected. Altogether, the results of the present work as well as previous studies show that the antigens involved in the protection induced by T. rangeli are expressed in different strains of this parasite. These findings could prove useful in vaccine preparation.

Several (glyco)(sphingo)lipids from different human pathogens have been characterized, and frequently many of these molecules are participating in host-pathogen interaction. In Leishmania (Leishmania) amazonensis, for example, amastigotes present on their surface glycosphingolipids (GSLs) with the structure Galbeta1-3Galalpha, which is recognized by 30 kDa receptor of macrophages. Furthermore, other Leishmania species, such as Leishmania (Leishmania) major and Leishmania (Viannia) braziliensis present glycosylinositolphospholipids (GIPLs) which are involved in Leishmania-macrophage interaction. It is worth to mention that these antigens are not expressed in mammalian cells. Leishmania promastigotes also present inositol phosphorylceramide (IPC), a unique sphingolipid characteristic of fungi and plants. It was observed that IPC synthesis is essential for parasite division, since Aureobasidin A, an inhibitor of IPC synthase, inhibited significantly promastigote and amastigote growths. Recently, it was also demonstrated that GIPLs, IPC and sterols are preferentially present in the parasite membrane microdomains resistant to Triton X-100 at 4 degrees C. The disruption of these microdomains by incubating parasites with methyl-beta-cyclodextrin inhibited significantly macrophage infectivity by Leishmania. Other pathogens, such as fungi, also present unique glycolipids which may have an important role for the fungal development and/or disease establishment. Taking together these results, this review will discuss different biological roles for (glyco)(sphingo)lipids of different pathogens.

High-throughputtechnologies inevitably produce vast quantities of data. This presents challenges in terms of developing effective analysis methods, particularly where the analysis involves combining data derived from different experimental technologies. In this investigation, a systematic approach was applied to combine microarray gene expression data, quantitative trait loci (QTL) data and pathway analysis resources in order to identify functional candidate genes underlying tolerance to Trypanosoma congolense infection in cattle. We automated much of the analysis using Taverna workflows previously developed for the study of trypanotolerance in the mouse model. Pathways represented by genes within the QTL regions were identified, and this list was subsequently ranked according to which pathways were over-represented in the set of genes that were differentially expressed (over time or between tolerant N'dama and susceptible Boran breeds) at various timepoints after T. congolense infection. The genes within the QTLthat played a role in the highest ranked pathways were flagged as good targets for further investigation and experimental confirmation.

It is now widely accepted that novel infectious disease can be a leading cause of serious population decline and even outright extinction in some invertebrate and vertebrate groups (e.g., amphibians). In the case of mammals, however, there are still no well-corroborated instances of such diseases having caused or significantly contributed to the complete collapse of species. A case in point is the extinction of the endemic Christmas Island rat (Rattus macleari): although it has been argued that its disappearance ca. AD 1900 may have been partly or wholly caused by a pathogenic trypanosome carried by fleas hosted on recently-introduced black rats (Rattus rattus), no decisive evidence for this scenario has ever been adduced. Using ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (AD 1888-1908), we were able to resolve unambiguously sequence evidence of murid trypanosomes in both endemic and invasive rats. Importantly, endemic rats collected prior to the introduction of black rats were devoid of trypanosome signal. Hybridization between endemic and black rats was also previously hypothesized, but we found no evidence of this in examined specimens, and conclude that hybridization cannot account for the disappearance of the endemic species. This is the first molecular evidence for a pathogen emerging in a naïve mammal species immediately prior to its final collapse.

Trypanosomes evade antibody-mediated lysis via antigenic variation and rapid antibody removal from their cell surface. Recently, in Cell, Engstler et al. (2007) have discovered the mechanism for antibody clearance. Hydrodynamic forces generated by trypanosome swimming create a current, causing surface-bound antibodies to act as "molecular sails." Consequently, they are swept to the cell posterior, internalized via the flagellar-pocket, and degraded. Hydrodynamic sorting is a novel biological process, possibly applicable in other contexts.

Trypanosome infections cause several major human diseases, including sleeping sickness and Chagas disease, which affect millions of people in Africa and South America, respectively. Although adenosine 3',5'-monophosphate (cAMP) signaling and regulation have been widely studied in mammalian systems, and these pathways provide targets for the treatment of numerous pathologies, a molecular understanding of cAMP signaling in trypanosomes remains incomplete. Recent studies in these parasites, however, have revealed diverse families of adenylyl cyclase and phosphodiesterase that regulate cAMP concentrations. Importantly, these enzymes differ pharmacologically and biochemically from their mammalian counterparts. In this review, we discuss recent developments, emerging ideas, and gaps in knowledge in this area of research, highlighting aspects of enzymes in the cAMP signaling pathway that may be good targets for antitrypanosomal drug therapy.

Common arthropod vectors for trypanosomes are flies, fleas and bugs. This study reports on an unknown trypanosome species isolated from naturally infected Haemaphysalis hystricis ticks, hereby, referred to as Trypanosoma KG1 isolate. The parasite has been successfully cultured in vitro with L929 or HEK 293T cell line as feeder cells. This trypanosome cannot survive in vitro without feeder cells. Following experimental infections of ticks, the trypomastigote-like and the epimastigote-like forms of this trypanosome could be detected by Giemsa-stained smears of the midgut and salivary glands of Ornithodoros moubata ticks which were made to feed on a culturing medium containing Trypanosoma KG1 isolate through an artificial membrane. Trypanosoma KG1 isolate could also be detected from Giemsa-stained smears of the haemolymph up to 30 days post-inoculation into the O. moubata haemocoel. Trypanosoma KG1 isolate cannot be propagated in laboratory animals including mice, rats, rabbits and sheep. A phylogenetic tree constructed with the 18S rRNA gene indicates that Trypanosoma KG1 is a member of the stercorarian trypanosomes.

Introduction: Trypanosoma rangeli is a species of trypanosome second to T. cruzi, that is infective to humans in Latin America. Variability in the biological, biochemical and molecular characteristics between different isolates isolates of this parasite have been recorded., Objective: Morphological and molecular characteristics were recorded from strains of T. rangeli that were isolated from different species of Rhodnius and maintained in different vertebrate species., Materials and Methods: Nineteen strains of T. rangeli were isolated from R. prolixus, R. pallescens and R. colombiensis in Colombia, R. ecuadoriensis in Peru and R. pallescens in Panama. Polymorphism of blood trypomastigotes in ICR mice was evaluated and pleomorphism of P53 strain of T. rangeli KP1(-) inoculated in mouse, marsupial and canine was studied. RAPD analysis (randomly amplified polymorphic DNA analysis) of 12 strains isolated from four species of Rhodnius was performed., Result: Based on the total length of blood trypomastigotes, three discrete groups were observed. The P53 strain showed significant differences in the size of blood trypomastigotes in mouse, marsupial and canine. RAPD analysis showed that the strains segregated into two branches corresponding to strains of T. rangeli KP1(+) and T. rangeli KP1(-). All strains of T. rangeli KP1(-) clustered according to the species of Rhodnius from which they were isolated., Conclusion: These data reveal, for the first time, a close association amongst T. rangeli strains and Rhodnius species, confirming that each species of Rhodnius transmits to vertebrate hosts a parasite population with clear phenotypic and genotypic differences. This is further evidence that supports the concept of clonal evolution of these parasites.

A comparative study on the response of four indigenous cattle breeds of Ethiopia, namely Abigar, Horro, Sheko and Gurage, to natural challenge of trypanosomosis in the Tolley-Gullele area of the Ghibe valley has been undertaken from August 2000 until August 2004. Fifty female yearlings each of Horro, Sheko and Abigar and 31 of the Gurage were purchased from their natural habitats and introduced in to medium to high tsetse-trypanosomosis challenge area of the Ghibe valley. While the natural habitats of first three breeds are naturally infested with tsetse flies and trypanosomosis, that of the Gurage is known to be very minimal, if any, and hence the Gurage breed was used in this study as the known susceptible breed. During the study animal health, production performance and tsetse fly situation were monitored monthly. The Sheko breed has manifested very significantly (p<0.001) high overall average packed cell volume (PCV) values (25%) compared to that of Abigar (24%), Horro (23%) and Gurage (22%). It also had the lowest mean trypanosome prevalence rate of 9% against 23% of Horro, 26% of Abigar and 27% of Gurage, and the least number of Berenil treatments (1.36) compared to Abigar (4.0), Horro (4.6) and Gurage (6.7). While the Abigar manifested high sensitivity and frequent death to PCV depression, the Horro showed strong resilience to PCV depression and better response to Berenil treatment assistance. At this stage the Sheko breed was also found to be equal to the other breeds in its reproductive performance. These results need to be substantiated with further in-depth investigation including immune response, animal behavior and environmental influences.

Four water buffalo calves (Bubalus bubalis) were each inoculated intravenously with 10(6)T. evansi (camel isolate) and the fifth calf kept as non-infected control. The blood and sera of all calves were examined every 4 days during the first month post-inoculation (pi) and then once weekly until the end of the experiment (88 days pi). They were examined for hematological and biochemical changes, liver and kidney function tests. Hemoglobin concentration (Hb%), packed cell volume (PCV) and red blood cell count were significantly decreased. Total leucocytic count, lymphocytes and monocytes showed significant increase. Liver function tests revealed significant elevation in the activity of lactate dehydrogenase enzyme (LDH), globulin, total biliruben and indirect biliruben while alkaline phosphatase enzyme showed significant decrease. Kidney function tests revealed significant decrease of both creatinine and urea.

Trypanosoma rangeli is a kinetoplastid protozoan parasite that has been found in the majority of Latin American countries, overlapping its distribution area with that of Trypanosoma cruzi, the causative agent of Chagas disease. This parasite shares the same reservoirs and vectors as T. cruzi. Triatomines from genus Rhodnius are considered the most susceptible hosts to infection. In this work, we report the susceptibility of different triatomine species (Rhodnius neglectus, Panstrongylus megistus, Triatoma infestans, T. sordida, T. braziliensis, and T. vitticeps) to experimental infection by T. rangeli isolated from Didelphis albiventris in a highly endemic region for Chagas disease. An intense parasitism was evidenced in feces (56% to 81%) of the majority of the species studied on the 10th day after infection, decreasing during the period of the experiment (30 days). T. vitticeps did not present parasites in feces at any time. All triatomine species presented parasites in the hemolymph. In T. vitticeps and P. megistus, this parasitism was scarce (6.3% and 6.6%, respectively). In the other species, the parasitism was variable (62.5% to 100%). Triatomine mortality varied between 3% to 40%, increasing during the infection in all species studied. The lowest mortality was observed for T. infestans. Also, we showed that only trypomastigotes forms from salivary glands, and hemolymph were infective for mice. We conclude that all triatomine species used were susceptible to infection by T. rangeli at different levels. There was no direct correlation between intensity of parasitism and mortality.

Human African trypanosomiasis (HAT), or sleeping sickness, describes not one but two discrete diseases: that caused by Trypanosoma brucei rhodesiense and that caused by T. b. gambiense. The Gambian form is currently a major public health problem over vast areas of central and western Africa, while the zoonotic, Rhodesian form continues to present a serious health risk in eastern and southern Africa. The two parasites cause distinct clinical manifestations, and there are significant differences in the epidemiology of the diseases caused. We discuss the differences between the diseases caused by the two parasites, with an emphasis on disease burden, reservoir hosts, transmission, diagnosis, treatment and control. We analyse how these differences impacted on historical disease control trends and how they can inform contemporary treatment and control options. We consider the optimal ways in which to devise HAT control policies in light of the differing biology and epidemiology of the parasites, and emphasise, in particular, the wider aspects of control policy, outlining the responsibilities of individuals, governments and international organisations in control programmes.

Human trypanosoma infections like the ones seen in Africa and South America are unknown in India. The only exception in literature is of two documented cases of a self-limiting febrile illness, being attributed to Trypanosoma lewisi like parasites. We are reporting an unusual case of trypanosomiasis from the rural parts of Chandrapur district in Maharashtra. An adult male farmhand who used to practice veterinary medicine also, presented with history of febrile episodes on and off since five months and drowsiness before admission to this Institute. Though routine blood and other investigations were within normal limits, the peripheral smear showed a large number of trypanosomes which morphologically resembled the species Trypanosoma evansi, the aetiological agent of surra - a form of animal trypanosomiasis. A battery of assays covering the spectrum of parasitology, serology, and molecular biology confirmed the infecting parasite to be T. evansi. Failure to demonstrate the central nervous system (CNS) involvement, as evidenced by the absence of parasite in cerebrospinal fluid (CSF) advocated the use of suramin - the drug of choice in early stage African trypanosomiasis without any CNS involvement. Suramin achieved cure in our patient. The case is being reported because of its unique nature as the patient was not immunocompromised and showed infestation with a parasite which normally does not affect human beings.

Penetration of the heteroxenous protozoan Trypanosoma rangeli into the salivary glands of its invertebrate host Rhodnius domesticus has been investigated here using different approaches. Electron microscopy showed that epimastigotes coming from the insect hemocoel cross the basal lamina that surrounds the salivary glands and penetrate through the gland cells cytoplasm. After reaching the gland lumen, epimastigote forms remain adhered to the gland cell microvilli by their flagella, while metacyclic trypomastigotes are found swimming free in the saliva. Analysis by flow cytometry, western blotting and hemolytic activity allowed to demonstrate the presence in T. rangeli of a hemolytic molecule with antigenic cross-reactivity with murine perforin, which could be used by the parasites to reach the salivary gland lumen. This molecule, which we named as rangelysin, has 120 kDa molecular weight, is able to induce hemolysis only in acidic pH, and is produced by both trypomastigote and epimastigote forms.

Epidemiological and clinical studies on Trypanosoma avium are lacking in the Middle East. The aims of this study were to determine the T. avium incidence in falcons from Kuwait, report clinical signs and find an effective therapy. Blood smears from 921 diseased and 56 healthy falcons were examined between May 2003 and April 2004. 12 birds 11.3%) were found infected by T. avium and ten of these were treated with melarsomine (Cymelarsan) at a dosage of 0.25 mg/kg intramuscularly for four days. All affected birds presented clinical signs, including incapacity of flying high, poor appetite, lethargy, loosing weight, weakness, dyspnoea and death. Signs disappeared within 1-7 days after administration of melarsomine. Trypomastigotes were not detected in blood smears made 1-7 days after the end of therapy. This study suggests that T. avium induces disease in falcons and that melarsomine can be an effective therapy eliminating both clinical signs and circulating trypomastigotes.

There are 11 different pathogenic trypanosomes in trypanosomiasis endemic regions of Africa. Their detection and characterisation by molecular methods relies on species-specific primers; consequently several PCR tests have to be made on each sample. Primers ITS1 CF and ITS1 BR, previously designed to amplify the internal transcribed spacer (ITS1) of rDNA, have been evaluated for use in a universal diagnostic test for all pathogenic trypanosomes. Blood was collected from 373 cattle and 185 camels. The primers gave constant PCR products with the stocks of each taxon tested. Members of subgenus Trypanozoon (T. brucei brucei, T. evansi, T. b. rhodesiense and T. b. gambiense) gave a constant product of approximately 480 bp; T. congolense, savannah 700 bp, T. congolense kilifi 620 bp and T. congolense forest 710 bp: T. simiae 400 bp, T. simiae tsavo 370 bp, T. godfreyi 300 bp and T. vivax 250 bp. The sensitivity of the test ranged from 10 pg for Trypanozoon, T. congolense clade and T. vivax to 100 pg for T. simiae and T. godfreyi. The primers detected cases of multi-taxa samples, although the sensitivity was reduced with an increase in the combinations. A better detection rate of trypanosome DNA was recorded with buffy coats than from direct blood. With the field samples, the diagnostic sensitivity was close to the sensitivity obtained using single reactions with species-specific primers for Trypanozoon 38/40 (95%) and T. congolense savannah 30/33 (90.9%) but was lower with T. vivax 25/31 (77.4%). The primers offer promise as a routine diagnostic tool through the use of a single PCR; however, further evaluation is recommended.

Trypanosoma evansi (Trypanosomatidae, Kinetoplastida) is a salivarian trypanosomatid that infects eight mammal orders spread over America, Europe and Asia. In Brazil, T. evansi is the etiological agent of "Mal de Cadeiras", a horse disease very often described in the region known as Pantanal do Mato Grosso. Few data concerning the genetic diversity and biology of subpopulations of T. evansi that circulate in Brazil are available. The factors that modulate the interaction of this parasite with its hosts also remain to be elucidated. Here we evaluated the course of experimental infection of six T. evansi isolates derived from domestic and wild animals in Swiss-Webster mice and three Mus musculus lineages. The follow-up included biological, immunological as well as biochemical and hematological parameters. The same isolates as well as three others were characterized by pulsed-field electrophoresis. Our results showed that T. evansi isolates displayed significant differences regarding behavior and morbidity patterns in the distinct mouse lineages. Nevertheless, these differences could not be correlated with pulsed-field electrophoresis profiles. Indeed, concerning this molecular marker, only microheterogeneity was observed. Moreover, we observed that the outcome of the infection is defined by both host genetic background and peculiarities (virulence factors) of the distinct T. evansi isolates. Anemia and hypoglycemia were the only features that could be observed in all mouse lineages, independently of the inoculated T. evansi subpopulation. In addition, our data also show that Mus musculus is a suitable model host for the study of the different pathogenetic features of T. evansi infection.

The hemocytes of Rhodnius prolixus were analyzed during the course of infection with the protozoan Trypanosoma rangeli. The following cell types were identified: prohemocyte, plasmatocyte, adipocyte, granular cell and oenocytoid. The number of these cells changes during the infection course thus indicating a cell response to infection of R. prolixus by T. rangeli. Transmission electron microscopy showed that plasmatocytes were able to ingest epimastigote forms of the parasite, which were then found within a parasitophorous vacuole. Amorphous material was seen within the vacuole suggesting that fusion of host cell lysosomes with the vacuole took place. Intravacuolar parasites in process of digestion were observed. In addition, reaction product indicative of the presence of acid phosphatase was observed in parasite-containing vacuoles. No dividing parasites were seen within the vacuole in contrast to what was observed outside the host cells.

Current treatments for diseases caused by apicomplexan and trypanosomatid parasites are inadequate due to toxicity, the development of drug resistance and an inability to eliminate all life cycle stages of these parasites from the host. New therapeutics agents are urgently required. It has recently been demonstrated that type II fatty acid biosynthesis occurs in the plastid of Plasmodium falciparum and Toxoplasma gondii and inhibitors of this pathway such as triclosan and thiolactomycin restrict their growth. Furthermore, Trypanosoma brucei has recently been demonstrated to use type II fatty acid biosynthesis for myristate synthesis and to be susceptible to thiolactomycin. As this pathway is absent from mammals, it may provide an excellent target for novel antimicrobial agents to combat these diverse parasites. Leishmania and Trypanosoma parasites produce ergosterol-related sterols by a biosynthetic pathway similar to that operating in pathogenic fungi and their growth is susceptible to sterol biosynthesis inhibitors. Thus, inhibition of squalene 2,3-epoxidase by terbinafine, 14alpha-methylsterol 14-demethylase by azole and triazole compounds and delta(24)-sterol methyl transferase by azasterols all cause a depletion of normal sterols and an accumulation of abnormal amounts of sterol precursors with cytostatic or cytoxic consequences. However, Leishmania parasites can survive with greatly altered sterol profiles induced by continuous treatment with low concentrations of some inhibitors and they also have some ability to utilise and metabolise host sterol. These properties may permit the parasites to evade treatment with sterol biosynthesis inhibitors in some clinical situations and need to be taken into account in the design of future drugs., (Copyright 2002 Elsevier Science B.V.)

The development of Trypanosoma musculi and Trypanosoma lewisi were studied in vitro in the presence of adherent splenic cells. Both parasites developed only when attached by their flagellar tips to adherent splenic cells. During the proliferation of T. musculi, the kinetoplast migrated towards the nucleus, and once in the vicinity of the nucleus, the nuclear division was triggered. The kinetoplast of T. lewisi did not migrate towards the nucleus, but remained at its original location. The nucleus and kinetoplast divided at the same time in both parasites, and parasites started dividing from their flagellar ends and T. musculi and T. lewisi daughter cells were formed within 48 h. The unavailability of the adherent splenic cells in vitro led the parasites to transform into round/oval nonviable forms.

Studies on the effects of gamma radiation on the infectivity of Trypanosoma rangeli (strain H14) for the vector Rhodnius prolixus revealed that (i) the LD(50) (lethal dose for 50% of bugs) for uninfected insects was 4147 rads; (ii) irradiated insects with a dose of 1200 rads subsequently infected with the flagellates exhibited a mortality of 45%, while uninfected irradiated insects showed a mortality of 5%, and infected nonirradiated insects exhibited 10% mortality; (iii) flagellates were present in the hemolymph of irradiated insects 7 days postinfection (p.i.), while in nonirradiated insects the parasites appeared in the hemocoel 18 days p.i.; (iv) T. rangeli infection decreased the number of hemocytes significantly and induced the formation of nodules in the hemolymph of both irradiated and nonirradiated insects; and (v) gamma irradiation affected the ultrastructural organization of the epithelial cells of the small intestine, principally the perimicrovillar membranes and microvilli. In this paper, we discuss the significance of the intestinal microenvironment of R. prolixus with regard to its interaction with T. rangeli., ((c) 2002 Elsevier Science (USA).)

In the present study, we report a simple method to induce high Trypanosoma rangeli differentiation in vitro, producing a large number of infective trypomastigote forms. Parasites from SC-58 (Brazil) and Choachi (Colombia) strains were cultivated at 27 degrees C in TC-100, Grace and DMEM media, each supplemented with 5% fetal bovine serum and prepared at three distinct pHs (6.0, 7.0, 8.0). Differentiation was microscopically evaluated at 0, 3 and 6 days after cultivation in each medium by determining the percentage of trypomastigotes in Giemsa-stained smears. Our data revealed similar results for both T. rangeli strains, showing (after 6 days of cultivation in DMEM medium, pH 8.0) the presence of about 80% of trypomastigotes. These culture-derived trypomastigotes proved to be infective to both Balb-C mice and Rhodnius spp, reaching the triatomine's salivary glands. Our results describe a new and easy method to induce high T. rangeli differentiation in vitro, allowing further studies on the antigenic constitution of trypomastigotes.

Experimental infection of Trypanosoma (Trypanozoon) evansi in Bandicota bengalensis produces an acute disease course leading to untimely death of the bandicoot rat. The sequential alteration of liver, spleen, lung, kidney, and heart was studied on the 5th, 8th, 12th, and 14th days postinoculation. The rats showed inflammatory, degenerative, and necrotic changes in these organs. In liver, pseudolobule formation, necrosis and hemorrhage within the sinusoids, and fatty degeneration of hepatic cells were the predominant histopathological changes. The changes were destructive and irreversible. In spleen giant cells aggregation and granulomatous lesion, i.e., accumulation of histiocytes, were the protective changes, whereas tissue and cell damage indicated irreversible degeneration. The gradual development of intrabronchus inflammation, aggregation of inflammatory cells around the alveoli, congestion of bronchioles, septal edema, atrophy of alveolar walls, migration of macrophages, and emphysema were the histopathological changes noticed in the lungs of the infected rats. The affected kidney showed infiltration of lymphocytes, hemorrhage in the interlobular space, and glomerulitis as the irreversible and destructive changes in the rats. There was degeneration of myocardium in the hearts of the rats. The histopathological changes in these organs are compared with those studied in surra, human sleeping sickness disease, and African trypanosomiasis. Possible mechanisms for these histological changes in the visceral organs are discussed., (Copyright 2001 Elsevier Science (USA).)

The susceptibility of four Rhodnius species to different Trypanosoma rangeli strains was evaluated using both intracoelomic inoculation and oral infection. Rhodnius prolixus, Rhodnius domesticus, Rhodnius neglectus and Rhodnius nasutus were infected with Trypanosoma rangeli Macias (Venezuela), Choachi (Colombia) and SC-58 (Brazil) strains, revealing distinct haemolymph and salivary glands infection rates. The obtained infection rates were revealed to be dependent on the method of infection and the triatomine species. Our results suggest the existence of a high adaptation between the strain and the local vector.

Six 6-month-old bulls were experimentally infected with five different isolates of Trypanosoma evansi; two received the same isolate and the other four received different isolates. The parasitaemias and serum antigen levels were monitored regularly by the haematocrit centrifuge technique (HCT) and antigen-detection ELISA (Ag-ELISA), respectively. Trypanosomal antigen was demonstrated by the Ag-ELISA by 10-14 days post inoculation in four cattle, while parasitaemias were first found to be positive in individual cattle over a longer period of time post inoculation (6-28 days). In two cattle, the Ag-ELISA values were also positive when the animals were found to harbour trypanosomes by the HCT and only turned negative 3 days after treatment, while the ELISA values fluctuated during the experiment in another two bulls. The remaining two cattle never produced positive ELISA results despite positive parasitological results. The antibody titres in all six cattle started to rise around 10 days post inoculation and then stayed high throughout the experiment. It was concluded that the Ag-ELISA would produce some false negative results in the early stages of T. evansi infection owing to variations in the balance of parasitaemia and antibody levels in the circulation, and in the pathogenicity of parasite strains.

This review focuses on interactions of HIV with the first-line defence of native immunity, the complement system. In all body compartments tested so far, HIV meets complement. Activation of the complement system results in deposition of C3 fragments on the viral surface, but in contrast to other pathogens, most of HIV is not or is only poorly lysed by membrane attack complexes. To survive complement-mediated lysis, HIV has not only developed resistance mechanisms, but uses opsonisation with complement fragments for its own advantage. Opsonised virions interact with complement receptor-expressing cells, which are either subsequently infected with high efficiency or retain viral particles on their surface, which promotes transmission of virus to other permissive cells. Our knowledge of these mechanisms has increased enormously over the past few years. A complete understanding of these complex interactions of HIV with the complement system opens new perspectives for development of alternative therapeutic strategies.

Objective: To determine the susceptibility of the agile wallaby (Macropus agilis) and the dusky pademelon (Thylogale brunil) to infection with Trypanosoma evansi., Method: Two agile wallabies and three dusky pademelons were experimentally infected with between 5 x 10(4) and 10 x 10(4) T evansi from a cryopreserved stabilate isolated from an indonesian buffalo. Animals were observed twice daily for clinical signs and blood was collected every 3 days to determine parasitaemia. Necropsy was conducted on animals that died or were euthanised when in extremis and representative tissue sections examined., Results: All wallabies developed a high parasitaemia by 6 days after infection, which persisted until death or euthanasia in extremis, between days 8 and 61. Clinical signs included anorexia, weakness and ataxia. Anaemia occurred in one wallaby that survived for 61 days. Gross pathological changes varied between animals. They included pericarditis, serous atrophy of fat, splenomegaly, ulcerative gastritis and enteritis. Histological changes were characterised by a mononuclear cell infiltration of the connective tissue of most organs with little cellular destruction. Striking lesions were seen in the choroid, heart, stomach and small intestine., Conclusion: Agile wallabies and pademelons are highly susceptible to infection with T evansi. Wallabies, therefore, have the potential to spread T evansi within New Guinea and Australia if infection is introduced. Mortality is likely to be high thereby acting as an indicator of recent introduction. Histological changes seen in wallabies infected with T evansi are diagnostic for infections occurring in Australia and Papua New Guinea.

An ultrastructural study of skeletal muscle alterations wascarried out in mice experimentally infected with Trypanosoma evansi. Manifested anomalies were found, in both muscle fibre and microvasculature. Muscle fibre changes included atrophy, autophagic vacuoles formation, mitochondrial degeneration, nuclei pyknosis and segmental necrosis. In another direction, the cytoplasm of capillary endothelial cells showed rough endoplasmic reticulum and mitochondrial swelling, as well as luminal infoldings; parasites were found in the endothelial cell cytoplasm. A mononuclear infiltrate, formed by macrophages and neutrophils, was also observed. This work shows that skeletal muscle is an important target tissue for Trypanosoma evansi.

The process of interaction of the Choachi strain of Trypanosoma rangeli with intestinal epithelial cells of Rhodnius prolixus was analyzed in experiments carried out in vitro and in vivo. For the in vitro experiments small fragments of the anterior region of the posterior midgut were incubated in the presence of the parasites, fixed, and processed for observation with the scanning electron microscope. Parasites attached to the surface of some epithelial cells, especially to the extracellular membrane layers (perimicrovillar membranes), were observed. For the in vivo experiments insects were infected with cultures of T. rangeli, sacrificed at different time intervals, and then processed for scanning and transmission electron microscopy. An intimate contact between the parasites and the membrane layers was observed. The parasites penetrated into cells that showed an electronlucent cytoplasm and a damaged surface, moved within the cytoplasm of the epithelial cell, reached the basal region, crossed the basal lamina, and entered the hemocoel.

Amongst the earliest eukaryotes, trypanosomes have developed conventional organelles but sometimes with extreme features rarely seen in other organisms. This is the case of the flagellum, containing conventional and unique structures whose role in infectivity is still enigmatic.

In this study 10.67% incidence of trypanosomosis was observed in 150 racing camels by Suratex (latex agglutination). A significant decrease (P<0.05) in RBC, Hb, PCV and lymphocyte was observed, while a significant (P<0.05) increase in WBC and neutrophils was noted in trypanosomosis positive samples. The blood chemistry parameters indicated that there was significant (P<0.05) decrease in iron and albumin, but no significant alteration was observed in alkaline phosphatase (ALP), alanine aminotransferase (ALT), asparate aminotransferase (AST), gamma glutamyltransferase (GGT), lactic dehydrogenase (LDH), urea, total protein, calcium, creatinine, phosphorous and magnesium.

Cells respond to environmental or cellular changes, rapidly switching protein activities from one state to another. In eukaryotes, a way to achieve these changes is through protein phosphorylation cycles, involving independent protein kinase and protein phosphatase activities. Current evidences show that phosphatases and kinases are also involved in the molecular basis of immune response and in disease such as diabetes obesity and Alzheimer. In protozoan parasites like Trypanosoma and Leishmania, several kinases and phosphatases have been identified, many of them have been cloned but in several cases their biological role remains undetermined. In this review, the state-of-the art is summarized and the role of phosphatases and kinases in biological phenomena such as remodeling, invasion and pathogenic capacity of protozoan parasites is described. The real chance to use these components of signal transduction pathways as target for chemotherapeutic intervention is also discussed (Rev Méd Chile 2000; 128: 1150-60).

Ten isolates of Trypanosoma evansi from the Pantanal region of Brazil, recently derived from coati (Nasua nasua, carnivora, Procyonidae), horses and dogs, were characterized on the basis of biological (experimental infections in Wistar rats) and biochemical (multilocus enzyme eletrophoresis) data. Biological data were analyzed by Nested analysis of variance and Kruskal-Wallis. Marked heterogeneity in virulence was observed in the isolates. Some of the isolates showed an undulating parasitaemia, typical for African trypanosomes. This biological heterogeneity did not correspond with the biochemical homogeneity observed in the T. evansi isolates. T. evansi has one of the widest distributions and greatest range of mammalian hosts and is widely recognized to have evolved from Trypanosoma brucei. Adaptability of T. evansi was not reflected in the variability of biochemical and molecular parameters studied to date. The variability in virulence was very significant, but not correlated with the host from which it was derived. These data suggested that, in the region studied, T. evansi is transmitted among both domestic and sylvatic animals in one single transmission cycle.

Wild and farmed freshwater fishes are widely and heavily parasitized by the haemoflagellate Trypanosoma carassii. In contrast, common carp, a natural host, can effectively control experimental infections by the production of specific anti-parasite antibodies. In this study we have identified and partially characterized mucin-like glycoproteins which are expressed in high abundance [(6. 0+/-1.7)x10(6) molecules.cell(-1)] at the surface of the bloodstream trypomastigote stage of the parasite. The polypeptide backbone of these glycoproteins is dominated by threonine, glycine, serine, alanine, valine and proline residues, and is modified at its C-terminus by a glycosylphosphatidylinositol membrane anchor. On average, each polypeptide carries carbohydrate chains composed of about 200 monosaccharide units (galactose, N-acetylglucosamine, xylose, sialic acid, fucose, mannose and arabinose), which are most probably O-linked to hydroxy amino acids. The mucin-like molecules are the target of the fish's humoral immune response, but do not undergo antigenic variation akin to that observed for the variant surface glycoprotein in salivarian trypanosomes. The results are discussed with reference to the differences between natural and experimental infections, and in relation to the recently delineated molecular phylogeny of trypanosomes.

A technique for the rapid field assessment of African animal trypanosomosis (AAT) was developed during studies in the Gambia. This involved gathering indigenous information from rapid-appraisal questionnaires addressed to local informants, the results of single tsetse surveys and evaluations of the prevalence of trypanosome infections in village cattle. Local informants included livestock owners and herdsmen and trained personnel such as livestock assistants. The answers to the questionnaires were weighted in order to translate them into semi-quantitative ranked estimates (zero, low, medium, high or very severe) of the severity of AAT problems. A similar ranking was also defined for tsetse and prevalence data in the Gambia. The three assessment methods generally gave complementary results leading to similar conclusions about the severity of tsetse-trypanosomosis problems in a survey area; inconsistencies usually suggested that additional information was needed. The rankings of AAT intensity were used to develop management guidelines for minimising the impact of AAT at different levels through control interventions or improved livestock management. The methodology was designed to provide reliable, up-to-date and cost-effective assessments of AAT problems. Emphasis was placed on the importance of the involvement, priorities and perceptions of village livestock owners and herdsmen in making these assessments.

The course of experimental infection and pathogenicity of an isolate of Trypanosoma evansi were investigated using eight infected and six uninfected control Yankasa sheep. The sheep were each infected intravenously via the jugular vein with approximately 2.0 x 10(6) T. evansi parasites. The effects of the parasite on body temperature, packed cell volume (PCV), haemoglobin, erythrocytes, total protein, were monitored three times a week for approximately 9 weeks. Body weights were determined once every week for the duration of the experiment. The results showed that all the infected sheep were positive for the parasite. The prepatent period varied between 3 and 6 days. T. evansi produced parasitaemic waves at an average of 8.3 days interval. Two distinct forms of the disease were produced namely, acute (4-14 days postinfection), and chronic (43-59 days postinfection). Anaemia was a distinct feature of the disease. While the mean rectal temperatures were significantly elevated (P < 0.05), the mean values of the haematological parameters of the infected sheep dropped significantly (P < 0.05) compared to the preinfection levels. Observed clinical signs included pale mucous membrane, epiphora, loss of appetite, emaciation, dullness and rough hair coat together with fluctuating pyrexia which in most cases coincided with rise in parasitaemia. It is suggested that the isolate of T. evansi is pathogenic for Yankasa sheep.