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Abstract Background Universities in Cameroon are playing an active part in HIV/AIDS research and much of this research is carried out by students, usually for the purpose of a dissertation/thesis. Student theses/dissertations present research findings in a much more comprehensive manner and have been described as the stepping-stone of a budding scientist’s potential in becoming an independent researcher. It is therefore important to verify how students handle issues of research ethics. Method Theses/dissertations on HIV/AIDS that described research studies involving the use of human research participants were screened to verify if research ethics approval and informed consent were obtained and documented. The contents of the consent forms were also qualitatively analyzed. Results Of 174 theses/dissertations on HIV, ethics approval was documented in 17 (9.77%) and informed consent in 77 (47.83%). Research ethics approval was first mentioned at all in 2002 and highly reported in the year 2007. Evidence of ethics approval was found for the first time in 2005 and informed consent first observed and evidenced in 1997. Ethics approval was mostly reported by students studying for an MD (14.01%) and was not reported in any Bachelors’ degree dissertation. Informed consent was also highly reported in MD theses (64.58%) followed by undergraduate theses (31.58%). Voluntary participation and potential benefits of the study were some of the common aspects dealt with in most of the consent forms. The right to discontinue participation in the study and management of residual samples were scarcely ever mentioned. Conclusions Overall, and given the current state of the art of research ethics around the world, student-scientists in Cameroon would seem to be merely kidding with research ethics. It is thus essential that training in health research ethics (HRE) be incorporated in the curriculum of universities in Cameroon in order that the next generation of scientists may be better equipped with thorough knowledge and practice of HRE. This, we believe, would be one way of fighting the occurrence of research scandals, which have not yet abated significantly, especially those arising from negligence or inexcusable ignorance.

Background: Malaria endemic countries need to assess efficacy of anti-malarial treatments on a regular basis. Moreover, resistance to artemisinin that is established across mainland South-East Asia represents today a major threat to global health. Monitoring the efficacy of artemisinin-based combination therapies is of paramount importance to detect as early as possible the emergence of resistance in African countries that toll the highest burden of malaria morbidity and mortality., Methods: A WHO standard protocol was used to assess efficacy of the combinations artesunate-amodiaquine (AS-AQ Winthrop ® ), dihydroartemisinin-piperaquine (DHA-PPQ, Eurartesim ® ) and artemether-lumefantrine (AM-LM, Coartem ® ) taken under supervision and respecting pharmaceutical recommendations. The study enrolled for each treatment arm 212 children aged 6-59 months living in Maradi (Niger) and suffering with uncomplicated falciparum malaria. The Kaplan-Meier 42-day PCR-adjusted cure rate was the primary outcome. A standardized parasite clearance estimator was used to assess delayed parasite clearance as surrogate maker of suspected artemisinin resistance., Results: No early treatment failures were found in any of the study treatment arms. The day-42 PCR-adjusted cure rate estimates were 99.5, 98.4 and 99.0% in the AS-AQ, DHA-PPQ and AM-LM arms, respectively. The reinfection rate (expressed also as Kaplan-Meier estimates) was higher in the AM-LM arm (32.4%) than in the AS-AQ (13.8%) and the DHA-PPQ arm (24.9%). The parasite clearance rate constant was 0.27, 0.26 and 0.25 per hour for AS-AQ, DHA-PPQ and AM-LM, respectively., Conclusions: All the three treatments evaluated largely meet WHO criteria (at least 95% efficacy). AS-AQ and AL-LM may continue to be used and DHA-PPQ may be also recommended as first-line treatment for uncomplicated falciparum malaria in Maradi. The parasite clearance rate were consistent with reference values indicating no suspected artemisinin resistance. Nevertheless, the monitoring of anti-malarial drug efficacy should continue. Trial registration details Registry number at ClinicalTrial.gov: NCT01755559.

Background: The introduction of genomics and biobanking methodologies to the African research context has also introduced novel ways of doing science, based on values of sharing and reuse of data and samples. This shift raises ethical challenges that need to be considered when research is reviewed by ethics committees, relating for instance to broad consent, the feedback of individual genetic findings, and regulation of secondary sample access and use. Yet existing ethics guidelines and regulations in Africa do not successfully regulate research based on sharing, causing confusion about what is allowed, where and when., Methods: In order to understand better the ethics regulatory landscape around genomic research and biobanking, we conducted a comprehensive analysis of existing ethics guidelines, policies and other similar sources. We sourced 30 ethics regulatory documents from 22 African countries. We used software that assists with qualitative data analysis to conduct a thematic analysis of these documents., Results: Surprisingly considering how contentious broad consent is in Africa, we found that most countries allow the use of this consent model, with its use banned in only three of the countries we investigated. In a likely response to fears about exploitation, the export of samples outside of the continent is strictly regulated, sometimes in conjunction with regulations around international collaboration. We also found that whilst an essential and critical component of ensuring ethical best practice in genomics research relates to the governance framework that accompanies sample and data sharing, this was most sparingly covered in the guidelines., Conclusions: There is a need for ethics guidelines in African countries to be adapted to the changing science policy landscape, which increasingly supports principles of openness, storage, sharing and secondary use. Current guidelines are not pertinent to the ethical challenges that such a new orientation raises, and therefore fail to provide accurate guidance to ethics committees and researchers.

To compare dynamics of localized meningitis epidemics (LE) by meningococcal (Nm) serogroup, we analyzed a surveillance database of suspected and laboratory-confirmed Nm cases from 373 health areas (HA) of three regions in Niger during 2002-2012 and one region concerned by NmC epidemics during 2015. We defined LE as HA weekly incidence rates of ≥20 suspected cases per 100,000 during ≥2 weeks and assigned the predominant serogroup based on polymerase chain reaction testing of cerebrospinal fluid. Among the 175 LE, median peak weekly incidence rate in LE due to NmA, W, X and C were 54, 39, 109 and 46 per 100,000, respectively. These differences impacted ability of the epidemic to be detected at the district level. While this analysis is limited by the small number of LE due to NmX (N = 4) and NmW (N = 5), further research should explore whether strategies for prevention and response to meningitis epidemics need to be adapted according to predominant meningococcal serogroups., Competing Interests: The authors have declared that no competing interests exist.

A report on the Second H3Africa Ethics Consultation Meeting, which was held in Livingstone, Zambia on 11 May 2015. The meeting demonstrated considerable evolution by African Research Ethics Committees on thinking about broad consent as a consent option for genomics research and biobanking. The meeting concluded with a call for broader engagement with policy makers across the continent in order to help these recognise the need for guidance and regulation where these do not exist and to explore harmonisation where appropriate and possible.

Background: Research ethics review is a critical aspect of the research governance framework for human subjects research. This usually requires that research protocols be submitted to a research ethics committee (REC) for review and approval. This has led to very rapid developments in the domain of research ethics, as RECs proliferate all over the globe in rhyme with the explosion in human subjects research. The work of RECs has increasingly become elaborate, complex, and in many cases urgent, necessitating supporting rules and procedures of operation. Guidelines for elaborating standard operating procedures (SOPs) for the functioning of RECs have also been proposed. The SOPs of well-placed and well-resourced RECs have tended to pay much attention to details, resulting, as a consequence, in generally long, elaborate, intricate and complex SOPs; a model that can hardly be replicated by other committees, equally under ethics review pressures, but working under much more constraining conditions in resource-destitute environments., Methods: In this paper, we looked at the content and length of SOPs from African RECs and compared them to the World Health Organization (WHO)'s guidelines as the gold standard. We also looked at the SOPs from the Ethics Review and Consultancy Committee (ERCC) of the Cameroon Bioethics Initiative that we elaborated in a simplified way in 2013, and compared them to the WHO's guidelines and to the other SOPs., Results: Sixteen SOPs from 14 African countries were collected from various sources. Their average length was of 30 pages. By comparison to the guidance of the WHO, only six of them were found acceptable with more than 70 % of the criteria from the gold standard that were fully described. Among those six, two of them were very long and detailed (65 and 102 pages), while the four remaining SOPs ranged from 16 to 24 pages. The ERCC SOPs are seven pages long but maintain all that is of essence for the rigorous, efficient and timely review of protocols., Conclusions: We are convinced that, because of their brevity, simplicity, clarity and user-friendliness, the ERCC SOPs recommend themselves as a model template to, at least, committees similarly situated and/or circumstanced as the ERCC of the Cameroon Bioethics Initiative is. In fact, brevity, clarity, simplicity and user-friendliness are recognized values. Whatever is brief and clear is better than what is not and saves time. What is simple and user-friendly is better than what is not even though the two have the same aims because it saves both time and mental energy. And if this be true in general, it is even truer of the context and its peculiar constraints that we are addressing.

Background: The rise in genomic and biobanking research worldwide has led to the development of different informed consent models for use in such research. This study analyses consent documents used by investigators in the H3Africa (Human Heredity and Health in Africa) Consortium., Methods: A qualitative method for text analysis was used to analyse consent documents used in the collection of samples and data in H3Africa projects. Thematic domains included type of consent model, explanations of genetics/genomics, data sharing and feedback of test results., Results: Informed consent documents for 13 of the 19 H3Africa projects were analysed. Seven projects used broad consent, five projects used tiered consent and one used specific consent. Genetics was mostly explained in terms of inherited characteristics, heredity and health, genes and disease causation, or disease susceptibility. Only one project made provisions for the feedback of individual genetic results., Conclusion: H3Africa research makes use of three consent models-specific, tiered and broad consent. We outlined different strategies used by H3Africa investigators to explain concepts in genomics to potential research participants. To further ensure that the decision to participate in genomic research is informed and meaningful, we recommend that innovative approaches to the informed consent process be developed, preferably in consultation with research participants, research ethics committees and researchers in Africa., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

The application of genomics technologies to medicine and biomedical research is increasing in popularity, made possible by new high-throughput genotyping and sequencing technologies and improved data analysis capabilities. Some of the greatest genetic diversity among humans, animals, plants, and microbiota occurs in Africa, yet genomic research outputs from the continent are limited. The Human Heredity and Health in Africa (H3Africa) initiative was established to drive the development of genomic research for human health in Africa, and through recognition of the critical role of bioinformatics in this process, spurred the establishment of H3ABioNet, a pan-African bioinformatics network for H3Africa. The limitations in bioinformatics capacity on the continent have been a major contributory factor to the lack of notable outputs in high-throughput biology research. Although pockets of high-quality bioinformatics teams have existed previously, the majority of research institutions lack experienced faculty who can train and supervise bioinformatics students. H3ABioNet aims to address this dire need, specifically in the area of human genetics and genomics, but knock-on effects are ensuring this extends to other areas of bioinformatics. Here, we describe the emergence of genomics research and the development of bioinformatics in Africa through H3ABioNet., (© 2016 Mulder et al.; Published by Cold Spring Harbor Laboratory Press.)

Background: The rise of genomic studies in Africa - not least due to projects funded under H3Africa - is associated with the development of a small number of biorepositories across Africa. For the ultimate success of these biorepositories, the creation of cell lines including those from selected H3Africa samples would be beneficial. In this paper, we map ethical challenges in the creation of cell lines., Discussion: The first challenge we identified relates to the moral status of cells living in culture. There is no doubt that cells in culture are alive, and the question is how this characteristic is relevant to ethical decision-making. The second challenge relates to the fact that cells in culture are a source of cell products and mitochondrial DNA. In combination with other technologies, cells in culture could also be used to grow human tissue. Whilst on the one hand, this feature increases the potential utility of the sample and promotes science, on the other it also enables further scientific work that may not have been specifically consented to or approved. The third challenge relates to ownership over samples, particularly in cases where cell lines are created by a biobank, and in a different country than where samples were collected. Relevant questions here concern the export of samples, approval of secondary use and the acceptability of commercialisation. A fourth challenge relates to perceptions of blood and bodily integrity, which may be particularly relevant for African research participants from certain cultures or backgrounds. Finally, we discuss challenges around informed consent and ethical review., Summary: In this paper, we sought to map the myriad of ethical challenges that need to be considered prior to making cell line creation a reality in the H3Africa project. Considering the relative novelty of this practice in Africa, such challenges will need to be considered, discussed and potentially be resolved before cell line creation in Africa becomes financially feasible and sustainable. We suggest that discussions need to be undertaken between stakeholders internationally, considering the international character of the H3Africa project. We also map out avenues for empirical research.

Background: Scientific publication is commonly used to communicate research findings and in most academic/research settings, to evaluate the potential of a researcher and for recruitment and promotion. It has also been said that researchers have the duty to make public, the findings of their research. As a result, researchers are encouraged to share their research findings with the scientific world through peer review publications. In this study, we looked at the characteristics and publication rate of theses that documented studies on human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome in Cameroon., Materials and Methods: TO CHECK IF A THESIS RESULTED IN A PUBLICATION, WE SEARCHED: A database of publications on HIV in Cameroon, African Journals Online, PubMed and Google scholar. For each publication we recorded if the student was an author, the position of the student in the author listing, the journal and where the journal was indexed. We also looked at the impact factor of the journals., Results: One hundred and thirty theses/dissertations were included in the study, 74.6% (97/130) were written as part of a medical degree (MD), 23.8% (31/130) a postgraduate (PG) degree and 1.5% (2/130) for a Doctorate/PhD. On a whole, 13.9% (18/130) of the theses resulted in at least one publication in a scientific journal with a total of 22 journal articles, giving a mean publication rate of 0.17 article/thesis, 86.4% (11/22) were indexed on PubMed, 9.1% (2/22) on African Journals Online and 4.6% (1/22) on Google scholar. One PG thesis led to two book chapters. The student was the first author in 22.7% (5/22) of the articles and not an author in 9.1% (2/22) of the articles. Student supervisor was an author in all the articles., Conclusion: This study reveals that most students in Cameroon failed to transform their theses/dissertations to scientific publications. This indicates an urgent need to sensitize students on the importance of presenting their research findings in scientific meetings and peer reviewed journals. There is also a great necessity to build capacity in scientific writing among university students in Cameroon.

The testing of dried blood spots (DBSs) for human immunodeficiency type 1 (HIV-1) proviral DNA by PCR is a technology that has proven to be particularly valuable in diagnosing exposed infants. We implemented this technology for HIV-1 early infant diagnosis (EID) and HIV-1 RNA viral load determination in infants born of HIV-1-seropositive mothers from remote areas in Cameroon. The samples were collected between December 2007 and September 2010. Fourteen thousand seven hundred and sixty-three (14,763) DBS samples from infants born of HIV-positive mothers in 108 sites nationwide were tested for HIV. Of these, 1452 were positive on first PCR analyses (PCR1), giving an overall infection rate of 12.30%. We received only 475 DBS specimen for a second PCR testing (PCR2); out of these, 145 were positive. The median HIV-1 RNA viral load for 169 infant DBS samples tested was 6.85 log copies/ml, with values ranging from 3.37 to 8 log copies/ml. The determination of the viral load on the same DBS as that used for PCR1 allowed us to bypass the PCR2. The viral load values were high and tend to decrease with age but with a weak slope. The high values of viral load among these infants call for early and effective administration of antiretroviral therapy (ART). The findings from this study indicate that the use of DBS provides a powerful tool for perinatal screening programs, improvement on the testing algorithm, and follow-up during treatment, and thus should be scaled up to the entire nation.

Unlabelled: Many ethical concerns surrounding human genetics studies remain unresolved. We report here the situation in Cameroon., Objectives:   To describe the profile of human genetic studies that used Cameroonian DNA samples, with specific focus on i) the research centres that were involved, ii) authorship, iii) population studied, iv) research topics and v) ethics disclosure, with the aim of raising ethical issues that emerged from these studies., Method:   Bibliometric Studies; we conducted a PubMed-based systematic review of all the studies on human genetics that used Cameroonian DNA samples from 1989 to 2009., Results and Discussion:   Fifty articles were identified, involving predominantly research centres from Europe (64%) and America (32%). Only 7 (14%) Cameroonian institutions and 14 (28%) Cameroonian authors were associated with these publications. At least 52% of publications were devoted to population genetics (variation/migration patterns) amongst 30 Cameroonian ethnic groups. Very few studies concerned public health related genetic issues and only 5 (10%) references were found for hemoglobinopathies like sickle cell anaemia. Almost all DNA samples are 'banked' outside of the African continent. Capacity building, rights to the genetic information and benefits to the individuals, communities and populations who contribute to these studies are addressed., Conclusions:   1) Our data suggests the need for a wider debate towards building capacity and addressing ethical issues related to human genomic research in sub-Saharan Africa and specifically in Cameroon; 2) National ethical guidelines and regulations concerning the collection, use and storage of human DNA are urgently needed in Cameroon., (© 2011 Blackwell Publishing Ltd.)

We assessed the extent of research ethics approval and informed consent reporting in publications emanating from Cameroon and indexed in PubMed from 2005-2009. In our review of 219 full-length articles, we found that 57.53% reported ethics approval, 70.78% informed consent, and 50.68% both ethics approval and informed consent. Reporting these procedures was more common in randomized clinical trials than in other study designs. Also, 59.52% of the articles on vulnerable populations documented ethics approval and 76.19% documented informed consent. This study also identified some structures for ethics review and recommends some next steps for research on the quality of ethics review in Cameroon.

Lymphocyte subset reference values used to monitor infectious diseases, including HIV/AIDS, tuberculosis, malaria, or other immunological disorders in healthy children in Cameroon, are lacking. Values for Caucasian cohorts are already being utilized for clinical decisions but could be inappropriate for African populations. We report here the immunological profile for children aged from birth through 6 years in Cameroon and also compare our values to data from other African and Caucasian populations. In a cohort of 352 healthy children, aged 0 to 6 years, the relative and absolute numbers of T-cell subsets, B cells, and NK lymphocytes were determined from peripheral blood collected in EDTA tubes. Samples were stained with BD Multitest reagents in Trucount tubes and analyzed by using CellQuest-Pro and FlowJo software. We evaluated about 23 different lymphocyte subsets in which the absolute number and percentage values differed significantly (P < 0.05) with age and peaked between 6 and 12 months. B-cell values were higher compared to reported values from developed countries. Differences in activated and differentiated T cells were observed in subjects between 1 and 6 years of age. The absolute CD8(+) T-cell count and the CD4(+)/CD8(+) ratio seem to depend on gender. Normal lymphocyte subsets values among children from Cameroon differ from reported values in Caucasian and some African populations. The differences observed could be due to genetic and environmental factors coupled with the methodology used. These values could be used as initial national reference guidelines as more data are assembled.

Background: Areas endemic for Plasmodium falciparum, hepatitis B virus (HBV) and hepatitis C virus (HCV) overlap in many parts of sub-Saharan Africa. HBV and HCV infections develop in the liver, where takes place the first development stage of P. falciparum before its further spread in blood. The complex mechanisms involved in the development of hepatitis may potentially influence the development of the liver stage of malaria parasites. Understanding the molecular mechanisms of these interactions could provide new pathophysiological insights for treatment strategies in Malaria., Methodology: We studied a cohort of 319 individuals living in a village where the three infections are prevalent. The patients were initially given a curative antimalarial treatment and were then monitored for the emergence of asexual P. falciparum forms in blood, fortnightly for one year, by microscopy and polymerase chain reaction., Principal Findings: At inclusion, 65 (20.4%) subjects had detectable malaria parasites in blood, 36 (11.3%) were HBV chronic carriers, and 61 (18.9%) were HCV chronic carriers. During follow-up, asexual P. falciparum forms were detected in the blood of 203 patients. The median time to P. falciparum emergence in blood was respectively 140 and 120 days in HBV- and HBV+ individuals, and 135 and 224 days in HCV- and HCV+ individuals. HCV carriage was associated with delayed emergence of asexual P. falciparum forms in blood relative to patients without HCV infection., Conclusions: This pilot study represents first tentative evidence of a potential epidemiological interaction between HBV, HCV and P. falciparum infections. Age is an important confounding factor in this setting however multivariate analysis points to an interaction between P. falciparum and HCV at the hepatic level with a slower emergence of P. falciparum in HCV chronic carriers. More in depth analysis are necessary to unravel the basis of hepatic interactions between these two pathogens, which could help in identifying new therapeutic approaches against malaria.

Background: Severe malaria and one of its most important pathogenic processes, cerebral malaria, involves the sequestration of parasitized red blood cells (pRBCs) in brain postcapillary venules. Although the pathogenic mechanisms underlying malaria remain poorly characterized, it has been established that adhesion of pRBCs to endothelial cells (ECs) can result in cell apoptosis, which in turn may lead to disruption of the blood-brain barrier. The nature of the parasite molecules involved in the pathogenesis of severe malaria remains elusive., Methods: Whole-transcriptome profiling of nonapoptogenic versus apoptogenic parasite field isolates obtained from Gabonese children was performed with pan-genomic Plasmodium falciparum DNA microarrays; radiolabeled instead of fluorescent cDNAs were used to improve the sensitivity of signal detection., Results: Our methods allowed the identification of 59 genes putatively associated with the induction of EC apoptosis. Silencing of Plasmodium gene expression with specific double-stranded RNA was performed on 8 selected genes; 5 of these, named "Plasmodium apoptosis-linked pathogenicity factors" (PALPFs), were found to be linked to parasite apoptogenicity. Of these genes, 2 might act via parasite cytoadherence., Conclusion: This is the first attempt to identify genes involved in parasite pathogenic mechanisms against human ECs. The finding of PALPFs illuminates perspectives for novel therapeutic strategies against cerebral complications of malaria.

Malaria and human African trypanosomiasis represent the two major tropical vector-transmitted protozoan infections, displaying different prevalence and epidemiological patterns. Death occurs mainly due to neurological complications which are initiated at the blood-brain barrier level. Adapted host-immune responses present differences but also similarities in blood-brain barrier/parasite interactions for these diseases: these are the focus of this review. We describe and compare parasite evasion mechanisms, the initiating mechanisms of central nervous system pathology and major clinical and neuropathological features. Finally, we highlight the common immune mediated mechanisms leading to brain involvement. In both diseases neurological damage is caused mainly by cytokines (interferon-gamma, tumour necrosis factor-alpha and IL-10), nitric oxide and endothelial cell apoptosis. Such a comparative analysis is expected to be useful in the comprehension of disease mechanisms, which may in turn have implications for treatment strategies.

Background: Nonhuman primates are raised in large numbers in research centers and zoos. Reproductive monitoring is required to improve breeding performances. Ultrasonography is a safe method to determine gestational age and to estimate the date of parturition. However only few data are available in nonhuman primates., Methods: Fetal biometric data were obtained throughout pregnancy on four African primate species, namely chimpanzee, gorilla, mandrill and patas monkey. Measurements included biparietal diameter, transverse abdominal diameter, femur and humerus length, external interorbital diameter, and fetal heart rate. Curves established from these data were compared with previously published data in chimpanzees and gorillas and with those for humans and other closely related primate species., Results: The curves for the different hominids were very similar, while those for mandrills more closely resembled baboons and data for patas monkeys were comparable to those for macaques., Conclusions: These data, by providing a tool to evaluate precise gestational age, will be useful for centers raising these four primate species.

Undertaking a HIV seroepidemiological survey in Sahel is logistically problematic, since countries like Niger or Mali are very large with scattered populations and harsh climatic conditions. Therefore, the replacement of serum samples by whole blood dried on filter papers has been studied for HIV-antibody testing with commercial kits that are commonly used. In Niger, two tests ELISA (Genscreen HIV1/2 version 2, Vironostika HIV Uni-Form II Ag/Ab) and two rapid tests (Determine HIV1/2 et Immunocomb II HIV1&2 Bispot) were used to compare the dried blood spots and serum samples from 43 control individuals. Both ELISAs gave an excellent correlation (r = 0.99 et r = 0.98) between the dried blood spots and serum absorbance values. Using the rapid tests, the HIV status was found 100% concordant with dried blood spots and serum samples. An algorithm using three out of the four mentioned tests was defined then validated on the dried blood spots of 163 control individuals (100% concordant). In conclusion, dried blood spots may accurately and profitably replace serum samples for the serodiagnosis of HIV infection and for mass serosurveys in Sahel.

In recent years, several studies have demonstrated the existence of cytokine-like molecules in invertebrates, therefore suggesting that cytokines may have been conserved throughout evolution. In this study, we investigated the presence of immunoreactive TNF alpha (ir TNF alpha) in the gastropod mollusc Biomphalaria glabrata, the specific intermediate host for the trematode Schistosoma mansoni. Immunocytochemical study indicated the presence of ir TNF alpha in mollusc hemocytes corresponding to a 53-kDa molecule detected by western blot analysis. Using ELISA tests, we demonstrated the presence of substantial amounts of ir TNF alpha in hemolymph, that were significantly decreased during the S. mansoni infection. The possible role of ir TNF alpha in the regulation of mollusc immune functions and in the host-parasite relationship is discussed.