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Spermathecae of female Glossina palpalis palpalis were examined to obtain data on their insemination. The study was conducted near the village of Zomenin in the forest area of Daloa (lat. 7-6° N, long. 7-8° W) in Côte d’Ivoire. Glossina were caught with Vavoua traps in four types of tsetse fly biotopes: coffee plantation (pupa site), edge between coffee plantation and forest, footpaths, and village outskirts. Out of 9175 Glossina examined, only a few had empty spermathecae (0.83%). The majority of virgin Glossina were immature females, which therefore had not fed yet (93.42%). They were mainly collected on pupa sites (71.05%) or on their edges (19.74%). No virgin female was found among Glossina that were 10 to 39 days of age. On the other hand, 0.05% of the 4460 very old Glossina (i.e. over 40 days of age) had empty spermathecae. Results suggest that Glossina insemination took place in pupa sites, a few days only after emergence of the imago (1-3 days). In addition, females of this species seemed to have mated before their first blood meal on the very site of emergence.

Des expériences de captures de G. p. palpalis ont été faites en utilisant le porc et l'homme dans le village de Noumousséria II (zone forestière de Daloa) en Côte d'Ivoire. L'analyse des résultats montre que : 1) les récoltes faites avec le porc sont 2,4 fois plus abondantes que celles réalisées avec l'homme; 2) le pourcentage de femelles capturées sur le porc est plus élevé (76,16 %) que celui des mâles alors que chez l'homme aucune différence n'apparaît entre les sexes; 3) l'amplitude des variations saisonnières est plus marquée chez le porc que chez l'homme. Du point de vue qualitatif, une similitude a été observée entre les échantillons de glossines prises avec le porc et ceux du piège biconique. Malgré le faible nombre de glossines marquées recapturées, il semblerait que les mouches tsé-tsé reviennent plus au porc (2 mouches tsé-tsé) qu'à l'homme (aucune)..

Des expériences en carrés latins ont été réalisées en Côte-d'Ivoire et au Congo, afin de comparer différentes variantes de pièges biconiques (Challier-Laveissière) et monoconiques. Quelle que soit l'espèce de glossines, de très bons rendements ont été obtenus avec les pièges monoconiques à écrans bleus ou a écrans croisés bleu-noir. Par contre, le piège monoconique à banderoles (Lancien) capture de 3 à 7 fois moins de glossines que le piège biconique, respectivement en Côte-d'Ivoire et au Congo. Un piège monoconique à un écran capture en moyenne 2 fois moins de mouches que son homologue à double écran. Les pièges avec cône supérieur en plastique transparent sont médiocres dans des conditions de fort ensoleillement. La nature du tulle utilisé pour le cône supérieur influence également le rendement

En zone forestière de Côte-d'Ivoire (région de Daloa), l'utilisation de 3 supports imprégnés de deltaméthrine à la dose de 300 mg/m.a./m2 en terroirs villageois Niaboua (piège biconique à Liabo, piège monoconique à Débo, écran à Bassaraguhé) en saison des pluies a montré : un effet immédiat et rapide des pièges aussi bien sur les glossines péridomestiques (zone de faible densité : pourcentage de réduction = 100 à Liabo, 93 à Débo) que sur celles des bas-fonds humides environnants (zone de haute densité : pourcentage de réduction = 85 à Liabo, 96 à Débo); un effet assez lent des écrans (glossines péridomestiques : pourcentage de réduction = 73, bas-fonds humides = 52). L'utilisation du piège monoconique (avec tulle moustiquaire) dans la lutte contre les tsé-tsé peut être préconisée

Background: Malaria is still a major public health concern in Côte d'Ivoire despite mass distribution of long-lasting insecticidal nets (LLINs) as a key preventive strategy. This study intended to evaluate the operational effectiveness of LLINs on the level of human-vector contact using 1 antibody-based biomarker of exposure to Anopheles in urban areas., Methods: This cross-sectional study collected socio-demographic data and use of LLINs from 9 neighborhoods in the city of Bouaké (Côte d'Ivoire). Dry blood spots performed in children aged >6 months and adults were used to evaluate immunoglobulin G (IgG) responses to the Anopheles gSG6-P1 salivary peptide., Results: IgG response levels to the salivary peptide were significantly lower in individuals who declared having "always" (n = 270) slept under an LLIN compared with those who had "often" (n = 2087) and "never" (n = 88) slept under an LLIN ( P  < .0001). IgG response levels to gSG6-P1 between those who declared having "always" and "not always" slept under an LLIN varied according to neighborhood, socio-professional category, and age group., Conclusions: The human IgG level to this gSG6-P1 salivary peptide could be a useful tool to evaluate the actual effectiveness of LLINs and help design behavioral change interventions that are crucial for sustaining universal coverage., (© The Author(s) 2020. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: In some African cities, urban malaria is a threat to the health and welfare of city dwellers. To improve the control of the disease, it is critical to identify neighbourhoods where the risk of malaria transmission is the highest. This study aims to evaluate the heterogeneity of malaria transmission risk in one city (Bouaké) in a West African country (Côte d'Ivoire) that presents several levels of urbanization., Methods: Two cross-sectional studies were conducted in three neighbourhoods (Dar-es-Salam, Kennedy and N'gattakro) in Bouaké during both the rainy and dry seasons. Data on insecticide-treated net (ITN) use and blood samples were collected from children aged between 6 months and 15 years to determine the parasite density and the prevalence of Plasmodium falciparum and the level of IgG against the Anopheles gSG6-P1 salivary peptide, used as the biomarker of Anopheles bite exposure., Results: The specific IgG levels to the gSG6-P1 salivary peptide in the rainy season were significantly higher compared to the dry season in all neighbourhoods studied (all p < 0.001). Interestingly, these specific IgG levels did not differ between neighbourhoods during the rainy season, whereas significant differences in IgG level were observed in the dry season (p = 0.034). ITN use could be a major factor of variation in the specific IgG level. Nevertheless, no difference in specific IgG levels to the gSG6-P1 salivary peptide was observed between children who declared "always" versus "never" sleeping under an ITN in each neighbourhood. In addition, the prevalence of P. falciparum in the whole population and immune responders was significantly different between neighbourhoods in each season (p < 0.0001)., Conclusion: This study highlights the high risk of malaria exposure in African urban settings and the high heterogeneity of child exposure to the Anopheles vector between neighbourhoods in the same city. The Anopheles gSG6-P1 salivary peptide could be a suitable biomarker to accurately and quantitatively assess the risk of malaria transmission in urban areas.

Urban malaria is an underestimated serious health concern in African countries. This study aimed to evaluate the risk of malaria transmission in an urban area by evaluating the level of human exposure to Anopheles bites using an Anopheles salivary biomarker ( gambiae Salivary Gland Protein-6 peptide 1 [gSG6-P1] peptide). Two multidisciplinary cross-sectional studies were undertaken in five sites of Bouaké city (three urban districts and two surrounding villages, used as control; Côte d'Ivoire) during the rainy season and the dry season. Blood samples were obtained from children 6 months to 14 years of age for immunological tests. The level of anti-gSG6-P1 immunoglobulin G (IgG) antibodies was significantly higher in the rainy season than the dry season in both urban and rural sites ( P < 0.0001). Interestingly, children with the highest anti-gSG6-P1 IgG responses in the rainy season were infected by Plasmodium falciparum . Surprisingly, no difference of anti-gSG6-P1 IgG level was observed between urban and rural areas, for either season. The current data suggest that children in the urban city of Bouaké could be as highly exposed to Anopheles bites as children living in surrounding villages. The immunological biomarker of human exposure to Anopheles bites may be used to accurately assess the potential risk of malaria transmission in African urban settings.

Background: Sleeping under a net, particularly a long-lasting insecticidal net (LLIN), is associated with reduced malaria morbidity and mortality, but requires high coverage and adherence. In this study, parasitologically confirmed Plasmodium falciparum infection and a clinical indicator (i.e. fever) were measured among children in three villages of central Côte d'Ivoire (Bozi, N'Dakonankro and Yoho) and associations with net coverage explored. In Bozi and Yoho, LLINs were provided by the national malaria control programme, prior to the study and an additional catch-up coverage was carried out in Bozi. In N'Dakonankro, no net intervention was conducted., Methods: Three cross-sectional surveys were carried out; two in the dry season (February 2010 and November 2011) and one in the rainy season (May 2012). Among 897 children aged <15 years, P. falciparum infection was determined by microscopy and a rapid diagnostic test (RDT). Fever was defined as an axillary temperature ≥37.5°C. A questionnaire was administered to obtain demographic data and net usage., Results: The proportion of children infected with P. falciparum according to microscopy in the third survey was 74%, 81% and 82% in Yoho, N'Dakonankro and Bozi, respectively. Meanwhile, 46% of the children in N'Dakonankro, 44% in Bozi and 33% in Yoho slept under a net. The risk of P. falciparum infection did not differ between net-sleepers and non-net-sleepers. Fewer children had parasitaemia ≥1,000 parasites/μl of blood in Bozi in the third compared to the first survey. Fever was poorly correlated with P. falciparum infection. The risk of P. falciparum infection did not depend on the village of residence, presence of fever or sleeping under LLIN the night before the survey. Conversely, it was higher in the rainy season and among older children., Conclusions: In an area where P. falciparum is highly prevalent, the use of nets was associated with significantly lower levels of parasitaemia. The apparent lack of effect on P. falciparum infection and fever might be explained by the relatively low net coverage in Bozi and Yoho and the relatively short period (<2 years) during which the impact of nets was measured.

Background: The use of long-lasting insecticidal nets (LLINs) is an effective malaria control strategy. However, there are challenges to achieve high coverage, such as distribution sustainability, and coverage keep-up. This study assessed the effect of LLINs coverage and contextual factors on entomological indicators of malaria in rural Côte d'Ivoire., Methods: The study was carried out between July 2009 and May 2012 in three villages (Bozi, N'Dakonankro and Yoho) of central Côte d'Ivoire. In Bozi and Yoho, LLINs were distributed free of charge by the national malaria control programme in 2008. In Bozi, an additional distribution was carried out in May 2011. No specific interventions were done in N'Dakonankro. Entomological surveys were conducted in July 2009 and July 2010 (baseline), and in August and November 2011 and in February 2012. Frequency of circumsporozoite protein was determined using an enzyme-linked immunosorbent assay. Regression models were employed to assess the impact of LLINs and changing patterns of irrigated rice farming on entomological parameters, and to determine associations with LLINs coverage and other contextual factors., Results: In Bozi, high proportion of LLIN usage was observed (95-100%). After six months, 95% of LLINs were washed at least once and 79% were washed up to three times within one year. Anopheles gambiae was the predominant malaria vector (66.6% of all mosquitoes caught). From 2009 to 2012, in N'Dakonankro, the mean annual entomological inoculation rate (EIR) increased significantly from 116.8 infectious bites/human/year (ib/h/y) to 408.8 ib/h/y, while in the intervention villages, the EIR decreased significantly from 514.6 ib/h/y to 62.0 ib/h/y (Bozi) and from 83.9 ib/h/y to 25.5 ib/h/y (Yoho). The risk of an infectious bite over the three-year period was significantly lower in the intervention villages compared to the control village (p<0.001)., Conclusion: High coverage and sensitization of households to use LLINs through regular visits (particularly in Bozi) and abandoning irrigated rice farming (in Yoho) resulted in highly significant reductions of EIR. The national malaria control programme should consider household sensitization and education campaigns and other contextual factors to maximize the benefit of LLINs.

Background: To improve effectiveness of malaria control interventions, it is essential to deepen the knowledge of contextual factors that govern people's practice for preventive and curative measures. The aim of this study was to determine factors that influence the use of long-lasting insecticidal nets (LLINs) in three rural communities of Côte d'Ivoire, two of which benefited from recent interventions., Methods: The study was carried out in 957 households in three villages (Bozi, N'Dakonankro and Yoho) located in central Côte d'Ivoire. Indicators of socioeconomic position (SEP), malaria knowledge and practice, placing special emphasis on LLINs, were investigated during a cross-sectional questionnaire survey. Principal component analysis was used to calculate the SEP of households by means of a list of household assets ownership. The concentration index was used to assess the direction of the association between SEP and a given variable. To compare groups or means, Fisher's exact test, χ2 and Kruskal-Wallis test were used, as appropriate., Results: Significant differences were found between SEP and reported malaria symptoms, such as fever or hot body, convulsion, anaemia and jaundice (yellow eyes). Individuals from the least poor group cited more often the use of bed nets and insecticide-treated nets (ITNs) compared to poorer groups. The mean number of individuals reporting the use of bed nets and LLINs was different between groups with different educational level. Moreover, the mean number of LLINs in a household was influenced by the presence of children below five years of age., Conclusion: The study not only confirmed that education and SEP play important roles in the prevention and control of malaria and promotion of health in general, but pointed at the basic essential knowledge and the key behavioural elements that should guide education and learning processes among the poorer segments of the population. In turn, such knowledge may change behaviour and lead to an increased utilization of LLINs.

The purpose of this study was to assess malaria transmission in an area of high coverage with long-lasting insecticidal nets (LLINs) in central Côte d'Ivoire. Two four-day larva collections were carried out in April and July 2008. Adult mosquito samples were collected by conducting human bait catches during a total of 80 man-nights. Vector infection rates were determined using an ELISA circumsporozoite antibody test. A total of 1582 mosquitoes were captured. Mansonia was the dominant genus in the culcidian fauna followed by Anopheles that was dominant in the anopheline fauna. The only Plasmodium vector was An. gambiae s.l. The high household bednet coverage rate probably accounted for the relatively low biting rate: 0.75 to 4.15 bites per person per night (b/p/n). Households not using bednets appear to have benefited from a passive protection effect associated with high LLIN coverage. Biting and entomological inoculation rates were 2.25 to 4.1 b/p/n (range) and 0.184 ib/p/n respectively in households that did not use LLINs and 0.75 to 4.15 b/p/n (range) and 0.341 ib/p/n respectively in households using LLINs.

Observations on the parasitism of Glossina palpalis palpalis by Hexamermis glossinae were carried out over a period of one year by catching flies at Abengourou, Aboisso and Daloa (forested area of Ivory Coast). No parasite is observed out of 2,168 Glossina palpalis palpalis caught in Abengourou and 9,732 in Aboisso. At Daloa, dissections of 7,341 Glossina reveal 1.75% parasited flies. All the worms were located in the abdominal cavity, loosely intertwined with the internal organ. Males were more infested than females (2.68% versus 1.26%). The parasites were more abundant among the nulliparous (2.30%) than the young parous (1.19%) and than the old parous (0.52%). The majority of infected flies were caught at the beginning of the rainy season (5.17%) and few in the dry season (0.23%). The low parasitic infection rate observed here indicates a minimal effect on the population dynamics of the vector of sleeping sickness in Ivory Coast.

Study of reproductive disorders were carried out through the dissection of 11,012 tsetse flies caught over a period of one year in forested different habitats of Glossina palpalis palpalis of Daloa in Ivory Coast. The proportion of females with reproductive disorders was very low and estimated at 0.79%. Out of 87 tsetse files with reproductive disorders, 93.10% were abortions, 5.77% were ovular blockage and 1.13% was uterine pupaison. Reproductive disorders were recorded from all age groups: 0.78% in young parous (out of 6,398 tsetse flies examined) and 0.80% in old parous (out of 4,614 tsetse flies dissequed). Our results show that reproductive disorders occur at any stage of the female pregnancy cycle. Amplifying these reproductive disorders using chemical compounds is proposed as a way of improving the efficacy of insecticide-impregnated targets (pour-on, traps and screens) of tsetse control in rain-forest areas.

Collections of Glossina with a biconical trap have been made for 6 years in the forest area of Daloa in Côte d'Ivoire. Three species of Glossina have been identified in the village of Batéguédéa II as well as in the plantations and gallery forests. They are: G. palpalis, G. pallicera and G. nigrofusca. G. palpalis was predominant in the village in 1984, representing 74% of the collection, while the G. pallicera and G. nigrofusca types are more common in plantations and gallery forest. In 1987, 3 years after the first observation, G. palpalis was the most common species in each of the three biotopes. G. palpalis was even more common in 1990, following a decline in the population of G. pallicera and G. nigrofusca in the village (0.2% for G. pallicera; 0.8% for G. nigrofusca) and the plantations (0.7% for G. pallicera; 1.3% for G. nigrofusca). However, these two species were still found in small numbers in the gallery forest.

The observations on the insemination of the Glossina palpalis have been made in the forest belt of Daloa in the Côte d'Ivoire through the test of the spermathecae of females caught in different biotopes. The testing of 8342 Glossina show that the ratio of females with empty spermathecae is low, with a rate of 0.88%. Most of the captured Glossina are tenerals or tsetse flies which have not yet been fed. We did not find a single virgin female among the young parous Glossina above the age of 9 days. However out of 3841 very old Glossina, 0.08% were found with empty spermathecae. Our results suggest that the Glossina's insemination took place earlier within the G. palpalis type, a few days before the adult (between 1 and 3 days).

Historically the region of Abengourou is a well-known of sleeping sickness in the forest area of Cote d'Ivoire. However data from epidemiologic studies carried out since 1980 show that this area is currently disease-free. This finding warrants study of glossina vectors to clarify the epidemiology of the disease in this area. Entomologic surveys were carried out over a period of one year. Traps were used to capture glossina in ten natural habitats: villages with or without pigs, coffee, cocoa and rice plantations, grazing lands, camping areas, uncultivated farmlands, trails, forest borderlands and wilderness. Findings documented almost total disappearance of zoophilic glossina (Glossina nigrofusca and Glossina pallicera) which accounted for less than 0.5% of glossina captured only during the rainy season. The apparent trap density (ATD) of Glossina palpalis, the main vector of disease, was low overall. However ATD values tended to be higher in villages with pigs (ATD : 2.07 glossina/trap/day) and forest borderlands (ATD : 2.63 glossina/trap/day) than in other habitants where values were always lower than 1 glossina/trap/day. This almost complete disappearance of Glossina palpalis can be attributed mainly to deforestation in most of the areas studied. This accounts for reduced contact with man. The absence of contact between man and anthropophilic glossins could explain that unlike Daloa and Vavoua sleeping sickness has disappeared from the region of Abengourou.

2,153 Glossina palpalis palpalis caught in biconical traps from different biotopes in relation with human activities in the forest areas of Côte d'Ivoire were used to calculate the trypanosome infection rates. The results showed that there was no preferential biotope for Glossina infected by trypanosomes. The most widespread species of trypanosomes infecting Glossina p. palpalis is T. congolense (10.13%) followed by T. vivax (8.22%) and seldomly by T. brucei (0.70%). Female Glossina are infected with trypanosomes (21.27%) more than the male ones (13.56%). Regarding female Glossina, the physiological age concerned by the first infection of T. vivax, T. congolense and T. brucei reached respectively 5, 15 and 35 days. These different infection rates vary in relation to seasons.

Tsetse control trials were carried out in forest zone of Côte d'Ivoire with biconical traps. Some of the traps were impregnated with deltamethrin (1, 2 g per trap) and others were not. Results show a rapid and effective action of the treated supports. In nine days, the tsetse population had been reduced by 85% on the treated supports and by 60% on the non treated supports. After one month, a rapid decrease of the efficacy of the treated traps was observed. The fall in the effectiveness (more masked in the treated traps) was certainly due to heavy rains (875 mm) which caused an important increase in growth of vegetation.

The biometric analysis of the male genitalia of Glossina palpalis palpalis and Glossina palpalis gambiensis about samples caught along four bits of road in Côte d'Ivoire permitted to determine the geographic limit between both subspecies. G. p. palpalis is everywhere in the Guinean area whereas G. p. gambiensis is found in the Sudanese one. In the wet savanna, both subspecies live together and mate to give out a reduced number of hybrids.