Exposition of Intermediate Hosts of Schistosomes to Niclosamide (Bayluscide WP 70) Revealed Significant Variations in Mortality Rates: Implications for Vector Control.

(1) Background: Schistosomiasis remains a public health issue in Cameroon. Snail control using Niclosamide can prevent schistosome transmission. It is safe to determine lethal concentrations for the population. This study aimed at assessing the toxicity of Niclosamide on different developmental stages of snail populations; (2) Methods: Snails were collected, identified, and reared in the laboratory. Egg masses and adult snails were exposed to Niclosamide, at increasing concentrations (0.06, 0.125, 0.25, 0.5, 1 mg/L for egg embryos and 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2 mg/L for adults). After 24 h exposure, egg masses and snails were removed from Niclosamide solutions, washed with source water and observed; (3) Results: Snail susceptibility was species and population dependent. For egg embryos, Biomphalaria pfeifferi was the most susceptible (LC50: 0.1; LC95: 6.3 mg/L) and Bulinus truncatus the least susceptible (LC50: 4.035; LC95: 228.118 mg/L). However, for adults, B. truncatus was the most susceptible (mortality rate: 100%). The LC50 and LC95 for Bi. camerunensis eggs were 0.171 mg/L and 1.102 mg/L, respectively, and were higher than those obtained for adults (0.0357 mg/L and 0.9634 mg/L); (4) Conclusion: These findings will guide the design of vector control strategies targeting these snail species in Cameroon.

Relationship between skin snip and Ov16 ELISA: Two diagnostic tools for onchocerciasis in a focus in Cameroon after two decades of ivermectin-based preventive chemotherapy.

BACKGROUND: Onchocerciasis elimination currently relies on repeated ivermectin-based preventive chemotherapy. Current World Health Organization's guidelines strongly recommend, though with low evidence of certainty, the use of Ov16 serology testing in children younger than 10 years old to assess whether mass drugs administration can be safely stopped. Therefore, more evidences are needed to support the use of this marker as sero-evaluation tool. This study aimed at determining the relationship between microfilaridermia and anti-Ov16 IgG4, and their variation according to age, gender and ivermectin intake history. METHODOLOGY: A cross-sectional survey was conducted in an area where ivermectin-based MDA has been implemented since more than 20 years. A questionnaire was used to record ivermectin intake history for the last 5 years. All volunteers aged ≥2 years were tested for microfilaridermia. IgG4 antibodies against Ov16 antigen were determined using the Standard Diagnostic Ov16 IgG4 ELISA kits and the recombinant anti-Ov16 AbD19432 antibodies. Prevalences, microfilaridermia counts and IgG4 concentrations were compared with regards to age, gender and history of ivermectin intake. PRINCIPAL FINDINGS: The prevalence of skin microfilariae was 23.4% (95% CI: 23.4-30.8), whereas Ov16 seroprevalence was 53.2% (95% CI: 47.9-58.4). A moderate positive percentage agreement (50.4%) and a high negative percentage agreement (69.2%) was found between skin snip and Ov16 serology in the whole population, while in children aged <10 years, the agreements were higher (positive percentage agreement: 62.6%; negative percentage agreement: 83.5%). In addition, no associations were found between ivermectin intake, Mf counts and estimated IgG4 concentration of participants. Anti-Ov16 IgG4 were higher in individuals harboring microfilariae than their negative counterparts (p<0.0001), though a negative correlation was found between skin microfilarial counts and anti-Ov16 IgG4 levels (r = -0.2400; p = 0.03). No variation in microfilarial counts according to age and gender was observed. Though positively correlated with age (r = 0.4020; p<0.0001), IgG4 was significantly different between the different age classes (p<0.0001). CONCLUSION/SIGNIFICANCE: Our results revealed moderate positive and negative agreements between parasitological and immunological parameters of onchocerciasis infection after several rounds MDA. Anti-Ov16 IgG4 levels increased with age but decreased with microfilarial counts, suggesting a variation of anti-Ov16 IgG4 as a result of constant exposure and accumulation of infection. This brings evidence sustaining the use of Ov16 serology in children as evaluation tool. However, additional investigations are needed to further reshape the appropriate age range among children aged <10 years old.

High infection rates for onchocerciasis and soil-transmitted helminthiasis in children under five not receiving preventive chemotherapy: a bottleneck to elimination.

BACKGROUND: The current mainstay for control/elimination of onchocerciasis and soil-transmitted helminthiasis (STH) relies on ivermectin- and mebendazole/albendazole-based preventive chemotherapies. However, children under five years of age have been excluded in both research activities and control programs, because they were believed to have insignificant infection rates. There is therefore a need for up-to-date knowledge on the prevalence and intensity of STH and onchocerciasis infections in this age group. This study aimed at assessing the rates and intensities of onchocerciasis and STH infections in children under five years of age who are excluded from ivermectin- or mebendazole/albendazole-based preventive chemotherapies. METHODS: A series of cross-sectional surveys was conducted in four Health Districts in the Centre and Littoral Regions of Cameroon between 2018 and 2019. All subjects aged 2 to 4 years, were screened for prevalence (or infection rate) and intensity [number of eggs per gram of stool (epg) or number of microfilariae per skin snip (mf/ss)] of STH and onchocerciasis infections respectively using the Kato-Katz and skin snip methodologies. Chi-square and the non-parametric tests (Mann Whitney and Kruskal Wallis) were used to compare infection rates and intensities of infections between Health Districts and genders, respectively. RESULTS: A total of 421 children were enrolled in this study. The overall prevalence of onchocerciasis was 6.6% [95% confidence interval (CI): 4.3‒9.9], ranging from 3.6% (in the Ntui Health District) to 12.2% (in the Bafia Health District). The intensity of infection ranged from 0.5 to 46 microfilariae per skin snip [median: 5; interquartile range (IQR): 2.25‒8.5]. The overall prevalence of STH was 9.6% (95% CI: 6.5‒13.9), with a high infection rate (29.6%) in the Akonolinga Health District. Two STH species (Ascaris lumbricoides and Trichuris trichiura) were found among infected individuals. The median intensities of STH infections were 1,992 epg (IQR: 210‒28,704) and 96 epg (IQR: 48‒168) for A. lumbricoides and T. trichiura, respectively. CONCLUSIONS: This study reveals that children < 5 years of age are highly infected with STH and onchocerciasis, and could contribute to the spread of these diseases, perpetuating a vicious circle of transmission and hampering elimination efforts. These findings reveal the urgent need to provide (or scale) treatments (likely pediatric formulations) to these preschool-aged children, especially in areas of high transmission, to accelerate efforts to reach WHO 2030 target.

Leishmaniasis in Cameroon: what is known and is done so far? A protocol for systematic review.

INTRODUCTION: The first visceral and cutaneous leishmaniasis cases were reported in Cameroon since more than six decades. However, interest in the disease has decreased over time and data on its epidemiology across the country are scanty. This systematic review aims to update data on what is known and done so far on leishmaniasis in Cameroon. METHODS AND ANALYSIS: PubMed/MEDLINE, EMBASE and Web of Science will be searched from inception onwards. Grey literature will be identified through Google Scholar searches, dissertation databases and other relevant documents such as report of the National Control Program. Searches will be conducted between January and February 2021. All studies reporting endemicity, distribution, infecting species, vectors and reservoirs will be eligible. The main outcomes will be epidemiological data (infection rate, distribution, infecting species, vectors and animal reservoir), while the secondary outcomes will be the cases management (diagnostic, treatment, reporting, intervention…). Two reviewers will independently screen eligible papers, and potential conflicts will be resolved by involving a third reviewer as an adjudicator. Methodological quality including bias will be appraised using a methodological quality critical appraisal checklist proposed in the Joanna Briggs Institute systematic review methods manual. A narrative synthesis will describe quality and content of the epidemiological evidence. Data on prevalence and vectors will be used to draw thematic maps of the distribution of leishmaniasis in Cameroon. ETHICS AND DISSEMINATION: This study will not require ethical approval as it will be based on already published or unpublished data. The final report of this review will be published in a peer-reviewed journal, and the outcomes will be used (1) as baseline information to design further studies that will help to better refine the epidemiological situation of leishmaniasis in Cameroon, and (2) to inform both programme managers and policy-makers of the situation of leishmaniasis in the country. SYSTEMATIC REVIEW REGISTRATION: This protocol was registered with the International Prospective Register of Systematic reviews (PROSPERO; registration number: CRD42020211864) database.

Support for families of isolated or deceased COVID-19 patients in sub-Saharan Africa.

Aside the direct effect of the COVID-19 on infected patients, this infectious disease outbreak has various psychological consequences. These mental health repercussions pertain to the general population of uninfected individuals, and particularly families of isolated or deceased COVID-19 patients. This aspect is of substantial interest amid sub-Saharan African communities, considering the key place and cultural significance of mourning and funerals in these settings. In this commentary, we discuss on the issue of psychological and social support of COVID-19 patients' families, by taking into account some sub-Saharan African cultural considerations.

Collateral Impact of Community-Directed Treatment with Ivermectin (CDTI) for Onchocerciasis on Parasitological Indicators of Loa loa Infection.

Ivermectin (IVM) is a broad spectrum endectocide whose initial indication was onchocerciasis. Although loiasis is not among its indications, IVM also exhibits antiparasitic activity against Loa loa. IVM-based preventive chemotherapies (PCs), so-called community-directed treatment with ivermectin (CDTI), have led to the interruption of transmission of onchocerciasis in some foci. A cross-sectional study was conducted in the Yabassi Health District where CDTI have been implemented since 20 years to fight onchocerciasis. All volunteers aged ≥ 5 years underwent daytime calibrated thick blood smears to search for L. loa microfilariae (mf). The prevalence of loiasis was 3.7% (95% CI: 2.2-6.2), significantly lower than its baseline prevalence (12.4%; 95% CI: 10.1-15.2; Chi-Square = 21.4; df = 1; p < 0.0001). Similarly, the microfilarial density was significantly low (mean = 1.8 mf/mL; SD = 13.6; max = 73,600) compared to baseline microfilarial density (mean = 839.3 mf/mL; SD = 6447.1; max = 130,840; Wilcoxon W = 179,904.5; p < 0.0001). This study revealed that the endemicity level of loiasis was significantly low compared to its baseline value, indicating a significant impact of IVM-based PC on this filarial disease. However, transmission is still ongoing, and heavily infected individuals are still found in communities, supporting why some individuals are still experiencing severe adverse events despite > 2 decades of CDTI in this Health District.

Serious limitations of the current strategy to control Soil-Transmitted Helminths and added value of Ivermectin/Albendazole mass administration: A population-based observational study in Cameroon.

BACKGROUND: Soil-transmitted helminth (STH) infections remain a public health concern in sub-Saharan Africa. School-based mass drug administration (MDA) using the anthelminthic drug Mebendazole/Albendazole have succeeded in controlling morbidity associated to these diseases but failed to interrupt their transmission. In areas were filarial diseases are co-endemic, another anthelminthic drug (Ivermectin) is distributed to almost the entire population, following the community-directed treatment with ivermectin (CDTI) strategy. Since Ivermectin is a broad spectrum anthelmintic known to be effective against STH, we conducted cross-sectional surveys in two health districts with very contrasting histories of Ivermectin/Albendazole-based PC in order to investigate whether CDTI might have contributed in STH transmission interruption. METHODOLOGY: Cross-sectional surveys were conducted in two health districts with similar socio-environmental patterns but with very contrasting CDTI histories (Akonolinga health district where CDTI was yet to be implemented vs. Yabassi health district where CDTI has been ongoing for two decades). Stool samples were collected from all volunteers aged >2 years old and analyzed using the Kato-Katz technique. Infections by different STH species were compared between Akonolinga and Yabassi health districts to decipher the impact of Ivermectin/Albendazole-based MDA on STH transmission. PRINCIPAL FINDINGS: A total of 610 and 584 participants aged 2-90 years old were enrolled in Akonolinga and Yabassi health districts, respectively. Two STH species (Ascaris lumbricoides and Trichuris trichiura) were found, with prevalence significantly higher in Akonolinga health district (43.3%; 95% CI: 38.1-46.6) compared to Yabassi health district (2.5%; 95% CI: 1.1-5.1) (chi-square: 90.8; df: 1; p < 0.001). CONCLUSION/SIGNIFICANCE: These findings (i) suggest that Mebendazole- or Albendazole-based MDA alone distributed only to at-risk populations might not be enough to eliminate STH, (ii) support the collateral impact of Ivermectin/Albendazole MDA on A. lumbricoides and T. trichiura infections, and (iii) suggest that Ivermectin/Albendazole-based PC could accelerate STH transmission interruption.