Mathias Eyong Esum

Biting midges belonging to the genus Culicoides are tiny stout-shaped hematophagous insects and are thought to transmit the filarial nematode Mansonella perstans. Little is known about the Culicoides fauna in the rain forest belt of the Littoral Region of Cameroon. This study was designed to investigate the diversity, abundance and distribution of Culicoides spp. and their role as the purported vector(s) of M. perstans. Overnight light trap collections and human landing catches (HLCs) revealed eight species of Culicoides with C. grahamii being the most abundant species followed by C. milnei. Four anthropophilic species (C. inornatipennis, C. grahamii, C. fulvithorax and C. milnei) were determined by the HLCs with a higher abundance in the 4–6 p.m. collections. The drop trap technique and Mp419 LAMP assay confirmed C. milnei to be the most efficient vector in enabling the development of the microfilarial stage to the infective larval form of M. perstans. The LAMP assay also revealed that natural transmission of this nematode is fostered by C. milnei and C. grahamii in the wild. In conclusion, C. milnei was shown to be the main vector of M. perstans in the rain forest belt of the Littoral Region of Cameroon.

Aims: Parasitic infections are a major cause of diseases and morbidity in Africa, with malaria inflicting the largest burden followed by schistosomiasis. Co-infection with schistosomiasis and malaria may lead to severe health effects on children harbouring both infections. Studies have suggested that co-infection with helminths and malaria alters haematological indices. This study investigated co-infection with Schistosoma species and Plasmodium falciparum amongst school-aged children in the Tiko Health District, South West Region of Cameroon. Methods: A community based study was conducted in three health areas (Holforth, Tiko Town and Likomba) of the Tiko Health District. Participants aged 5 – 15 years were enrolled into the study. Blood, urine and stool samples were collected from the participants after obtaining consent from their parents. Samples were examined using Microscopy and Polymerase Chain Reaction. Haemoglobin levels were measured using a haemoglobinometer. A total of 397 participants were enrolled into the study. Results: The prevalence of schistosomiasis, falciparum malaria and co-infection amongst school aged children were 16.1%, 44.3% and 7.8% respectively. Prevalence of anaemia was 38.0%. Those co-infected had the highest prevalence of anaemia (54.8%) than the mono-infected participants though this difference was not statistically significant (x² = 3.96, P = 0.138). Co-infection was associated with the health area (x² = 13.878, P = 0.001) and visit to the stream (x²= 7.223, P = 0.007). There was an association between co-infection and malaria parasite density (x² = 7.525, P = 0.0232). Conclusion: There was a relatively low prevalence of co-infection of schistosomiasis and malaria in school-aged children in the Tiko Health District. With respect to anaemia severity, there was no observed association between the infection category and severity of anaemia among the participants (x² = 5.64, P = 0.464).

INTRODUCTION: Measles is an infectious viral disease that affects susceptible individuals of all ages. It is a leading cause of death among young children globally due to suboptimal vaccination coverage. In 2019, measles outbreaks affected several parts of the world, including three health districts (HDs) of Cameroon´s South West Region (SWR) experiencing armed conflict. Herein, we assessed the factors associated with the outbreak in the SWR. METHODS: we conducted a comparative study from March to August 2020. Data on study participants were compared between the three HDs that experienced a measles outbreak and three other HDs of the region that reported a case of measles but did not get into an outbreak. Records on vaccination between 2015 and 2019 were reviewed. RESULTS: information was obtained from 56 participants with known measles status, 32 from outbreak districts, and 24 from non-outbreak districts. The population in the outbreak group was more likely to have traveled from an area in a measles´ outbreak (OR 2, 95%CI 1.1-11.20). There was a suboptimal availability of measles vaccines in both categories of districts compared to the needs, and there was a downward trend in vaccination coverage in both groups. In addition, vaccines were more exposed to extreme temperatures in HDs with the outbreak (P

Background: Although a few studies have assessed occupational exposure and knowledge on post-exposure prophylaxis (PEP) for HIV among health care workers (HCWs), limited information is available on the factors that influence the use of HIV PEP among HCWs after occupational exposure in Cameroon. This study aimed to assess the prevalence and determinants of occupational exposure to HIV infection and identify factors (knowledge, attitudes, and practices) that influence compliance to the use of HIV PEP among HCWs in the Biyem-Assi, Buea, and Limbe health districts. Methods: A stratified cross-sectional study was carried out among health care workers from the Biyem-Assi, Buea, and Limbe health districts of Cameroon. A structured questionnaire adapted from previous studies was administered on the socio-demographic status, occupational exposure to biological agents as well as information on knowledge, awareness of PEP guidelines, attitude, and practice of the HCWs towards HIV PEP. Results: Of the 312 participants, 198 (63.5%) experienced an occupational injury, and 240 (76.9%) had a good attitude towards HIV PEP. Age, place of work, and inadequate knowledge were determinants of occupational exposure. Whereas, awareness of PEP guidelines and being a medical doctor influenced compliance with HIV PEP, with 158 (51.0%) having adequate knowledge of the guidelines. Out of the 198 who experienced occupational injury, 114 (57.6%) adopted the good practice and 60 (30.3%) made use of HIV PEP. Conclusion and Global Health Implications: Over half of health care workers had occupational exposure to HIV with poor utilization of post-exposure prophylaxis though they were aware and knowledgeable of PEP guidelines and exhibited good practice. Compliance with HIV PEP utilization was influenced by gender, awareness of PEP guidelines, and specialty of the health care worker. Copyright © 2022 Eyong et al. Published by Global Health and Education Projects, Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution License CC BY 4.0.

Background: Onchocerciasis control using ivermectin alone has been achieved in some endemic savannah zones of Africa. In the forest regions, the co-endemicity with Loa loa has led to severe adverse events (SAEs) resulting in poor adherence of community members to ivermectin mass drug administration (MDA). This may jeopardize achieving the interruption of transmission of onchocerciasis. Therefore, to accelerate the elimination of onchocerciasis in L. loa co-endemic zones, alternative treatment strategies (ATS) including ground larviciding may be necessary. This study aimed at identifying Simulium breeding sites, cytospecies, transmission profile, susceptibility of Simulium larvae to insecticide (temephos) and identification of some non-target aquatic fauna prior to the implementation of the COUNTDOWN consortium ground larviciding alternative strategy in the Meme River Basin in South West Cameroon. Methods: A topographic map and entomological survey were used to determine breeding sites. Larvae and adults were identified using standard identification keys. Susceptibility tests were carried out on collected larvae by exposing them to decreasing concentrations of temephos and assessing survival rates while the cytospecies were identified using cytotaxonomy. Various entomological indicators were assessed from dissected flies. Fishing was used as proxy to traps to assess some aquatic fauna at different sites. Results: Twenty-two breeding sites were prospected in the Meme River Basin with eight productive for larvae. A concentration of 0.5–0.1 mg/l temephos induced 100% larval mortality. As the concentration of temephos decreased from 0.05 to 0.0025 mg/l, mortality of larvae also decreased from 98.7 to 12%. Nine cytospecies were observed in the Meme River Basin; 13,633 flies were collected and 4033 dissected. A total of 1455 flies were parous (36.1%), 224 flies were infected (5.5%), and 64 were infective (1.6%). Aquatic fauna observed included Cyprinus spp., Clarias spp., crabs, tadpoles, beetles and larvae of damsel fly. Conclusions: Onchocerciasis is being actively transmitted within the Meme River Basin. Simulium larvae are susceptible to temephos, and nine cytospecies are present. Non-target fauna observed included fishes, frogs, crabs and insects. Besides treatment with ivermectin, vector control through ground larviciding may be a complementary strategy to accelerate onchocerciasis elimination in the study area. Graphical

Background: Infections with Onchocerca volvulus nematodes remain a threat in Sub-Saharan Africa after three decades of ivermectin mass drug administration. Despite this effort, there is still an urgent need for understanding the parasite biology especially the mating behaviour and nodule formation as well as the development of more potent drugs that can clear the developmental (L3, L4, L5) and adult stages of the parasite and inhibit parasite reproduction and behaviour. Methodology/Principal findings: Prior to culture, freshly harvested O. volvulus L3 larvae from dissected Simulium damnosum flies were purified by centrifugation using a 30% Percoll solution to eliminate fly tissue debris and contaminants. Parasites were cultured in both cell-free and cell-based co-culture systems and monitored daily by microscopic visual inspection. Exhausted culture medium was replenished every 2–3 days. The cell-free culture system (DMEM supplemented with 10% NCS) supported the viability and motility of O. volvulus larvae for up to 84 days, while the co-culture system (DMEM supplemented with 10% FBS and seeded on LLC-MK₂ feeder cells) extended worm survival for up to 315 days. Co-culture systems alone promoted two consecutive parasite moults (L3 to L4 and L4 to L5) with highest moulting rates (69.2±30%) observed in DMEM supplemented with 10% FBS and seeded on LLC-MK₂ feeder cells, while no moult was observed in DMEM supplemented with 10% NCS and seeded on LEC feeder cells. In DMEM supplemented with 10% FBS and seeded on LLC-MK₂ feeder cells, O. volvulus adult male worms attached to the vulva region of adult female worms and may have mated in vitro. Apparent early initiation of nodulogenesis was observed in both DMEM supplemented with 10% FBS and seeded on LLC-MK₂ and DMEM supplemented with 10% NCS and seeded on LLC-MK₂ systems. Conclusions/Significance: The present study describes an in vitro system in which O. volvulus L3 larvae can be maintained in culture leading to the development of adult stages. Thus, this in vitro system may provide a platform to investigate mating behaviour and early stage of nodulogenesis of O. volvulus adult worms that can be used as additional targets for macrofilaricidal drug screening.

Background: The impact of large scale Mass Drug Adminstration (MDA) of ivermectin on active onchocerciasis transmission by Simulium damnosum, which transmits the parasite O. volvulus is of great importance for onchocerciasis control programmes. We investigated in the Mbam river system area, the impact of MDA of ivermectin on entomological indices and also verify if there are river system factors that could have favoured the transmission of onchocerciasis in this area and contribute to the persistence of disease. We compared three independent techniques to detect Onchocerca larvae in blackflies and also analyzed the river system within 9 months post-MDA of ivermectin. Method: Simulium flies were captured before and after 1, 3, 6 and 9months of ivermectin-MDA. The biting rate was determined and 41% of the flies dissected while the rest were grouped into pools of 100 flies for DNA extraction. The extracted DNA was then subjected to O-150 LAMP and real-time PCR for the detection of infection by Onchocerca species using pool screening. The river system was analysed and the water discharge compared between rainy and dry seasons. Principal findings: We used human landing collection method (previously called human bait) to collect 22,274 adult female Simulium flies from Mbam River System. Of this number, 9,134 were dissected while 129 pools constituted for molecular screening. Overall biting and parous rates of 1113 flies/man/day and 24.7%, respectively, were observed. All diagnostic techniques detected similar rates of O. volvulus infection (P = 0.9252) and infectivity (P = 0.4825) at all monitoring time points. Onchocerca ochengi larvae were only detected in 2 of the 129 pools. Analysis of the river drainage revealed two hydroelectric dams constructed on the tributaries of the Mbam river were the key contributing factor to the high-water discharge during both rainy and dry seasons. Conclusion: Results from fly dissection (Microscopy), real-time PCR and LAMP revealed the same trends pre- and post-MDA. The infection rate with animal Onchocerca sp was exceptionally low. The dense river system generate important breeding sites that govern the abundance of Simulium during both dry and rainy seasons.

Introduction Onchocerciasis is targeted for elimination mainly with annual community-directed treatment with ivermectin (CDTI). High infection levels have been reported in South-West Cameroon, despite ≥15 years of CDTI. The aim of this study was to assess factors associated with continued onchocerciasis transmission and skin disease. Methods A large-scale cross-sectional study was conducted in 2017 in 20 communities in a loiasis-risk area in South-West Cameroon. A mixed-methods approach was used. Associations between infection levels, skin disease and adherence to CDTI were assessed using mixed regression modelling. Different community members’ perception and acceptability of the CDTI strategy was explored using semi-structured interviews. Results Onchocerciasis prevalence was 44.4% among 9456 participants. 17.5% of adults were systematic non-adherers and 5.9% participated in ≥75% of CDTI rounds. Skin disease affected 1/10 participants, including children. Increasing self-reported adherence to CDTI was associated with lower infection levels in participants aged ≥15 years but not in children. Adherence to CDTI was positively influenced by perceived health benefits, and negatively influenced by fear of adverse events linked with economic loss. Concern of lethal adverse events was a common reason for systematic non-adherence. Conclusion CDTI alone is unlikely to achieve elimination in those high transmission areas where low participation is commonly associated with the fear of adverse events, despite the current quasi absence of high-risk levels of loiasis. Such persisting historical memories and fear of ivermectin might impact adherence to CDTI also in areas with historical presence but current absence of loiasis. Because such issues are unlikely to be tackled by CDTI adaptive measures, alternative strategies are needed for onchocerciasis elimination where negative perception of ivermectin is an entrenched barrier to community participation in programmes.