Evaluation of Schistosoma mansoni morbidity one year after praiquantel treatment in rhino camp and Obongi in West Nile, Uganda

An evaluation study on reversibility of Schistosoma mansoni induced periportal fibrosis (PF) morbidity following treatment with praziquantel, 40mg/kg body weight after one year, was carried out in Rhino Camp and Obongi all are West Nile districts in northern Uganda. To assess the reversibility of Schistosoma (S) mansoni induced PFs morbidity following treatment with praziquantel, 40mg/kg body weight after one year. The design was a Prospective cohorts study; and the setting was a busy canoe landing sites along Albert Nile in Schistosoma (S) mansoni hyperendemic areas of Rhino Camp and Obongi fishing village were selected for the study. Previously in 2005, 1562 people including fishermen and women, school pupils, teachers, and civil servants were studied in both fishing villages for S. mansoni using Kato/Katz stool smear method. Abdominal ultrasonography and sonomorphological abnormalities of periportal fibrosis were performed with Aloka portable ultrasound machine (Hellige, Freiburg, Germany) fitted with a convex probe of 3.5 mega Hertz was also performed in the field clinic on all patients who had S. mansoni eggs in their faeces. The sonomorphological abnormalities of periportal fibrosis were categorised and organomorphometry of liver and spleen was done. One thousand two hundred and seventy three 1273 (81.5%) patients in Rhino Camp and Obongi fishing villages were found to be excreting from 100 to ≥ 500 eggs per gram (epg) of faeces of S. mansoni eggs. Two hundred and eighty nine (18.5%) did not have eggs of S.mansoni in their faeces. All the 1273 patients secreting eggs of S.mansoni in their stool in Rhino Camp and Obongi fishing villages had abdominal ultrasonography and sonomorphological abnormalities of periportal fibrosis. Eight hundred and forty 840 (66%) although excreted S. mansoni eggs in their stool had Pf (0); Pf grade (I), n=259 (20.3%); Pf grade (II) n =147 (11.5%); and Pf grade (III) n=27 (2.1%) were observed

"Slash and Clear", a Community-Based Vector Control Method to Reduce Onchocerciasis Transmission by Simulium sirbanum in Maridi, South Sudan: A Prospective Study

Background: High ongoing Onchocerca volvulus transmission was recently documented in Maridi County, South Sudan. To complement community-directed treatment with ivermectin (CDTI) as the main onchocerciasis control strategy, we initiated a community-based vector control method “slash and clear” at the Maridi dam, a Simulium damnosum s.l. breeding site, to reduce O. volvulus transmission. Methods: Simulium damnosum s.l. biting rates were collected before and during the twenty months following the “slash and clear” intervention using the human landing catches. Black flies were dissected to measure parity rates before and twelve months after the intervention. Larvae and pupae of S. damnosum s.l. were collected from the dam for morphological and chromosomal characterization to identify the cytospecies involved. Results: Biting rates of S. damnosum s.l. close to the Maridi dam spillway decreased by >90% post-“slash and clear” for more than six months. Twelve months after the “slash and clear” intervention, the reduction in biting rates was still at <50% (p = 0.0007). Parity rates reduced from 13% pre-“slash and clear” (November 2019) to 5.6% post-“slash and clear” (November 2020). Larvae collected from the dam were identified as Simulium sirbanum. Conclusion: The “slash and clear” method was found to be an effective and cheap community-based method to reduce black fly biting rates caused by S. sirbanum. When repeated at least annually together with a high CDTI coverage, this intervention has the potential to considerably accelerate onchocerciasis elimination

Successful interruption of the transmission of Onchocerca volvulus in Mpamba-Nkusi focus, Kibaale district, mid-western Uganda

Background: The Mpamba-Nkusi onchocerciasis focus is situated in the mid-western part of Uganda. It has an area of 300 km2 and used to have Simulium neavei as the vector which develops in a phoretic association on freshwater crabs. Ground larviciding with temephos (Abate EC500) was initiated in June 2002. All the 330 communities in this focus have undergone annual treatment with ivermectin since 1995 and were later shifted to semi-annual treatment in 2009.Objective: To establish the impact of mass drug administration in combination with larviciding on the interruption of O. volvulus transmission.Design: Longitudinal studySetting: Rural areas in Mpamba-Nkusi focus, Kibaale district.Subjects: Individuals five years and above living in the focus.Interventions: Annual and semi-annual treatment with ivermectin supplemented by vector elimination were used. Epidemiological, entomological and serological assessments were conducted.Results: Freshwater crabs (n = 14,391) caught from monitoring sites (n = 41) since 2008 were negative for immature stages of S. neavei. The S.neavei population was reduced following trial and initiation of ground larviciding. No adult S. neavei has been caught in the focus for over five years. Parasitological examination of individuals residing in the focus revealed a microfilaria (mf) prevalence of 0.3% (95% CI 0 – 0.65%; n = 732) in 2012. Serological assays testing for Onchocerca volvulus antibodies conducted on 3351 children &lt;15 years in 2009 indicated point prevalence of 0.6% , (95% CI, 0.3-0.8%) while in 2012 another survey conducted among 3,407 children, only 1/3407 (0.03%, 95% CI, 0-0.09%) individual was positive for O. volvulus antibodies.Conclusions: Epidemiological and entomological findings suggest that interruption of transmission has been achieved

Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity

Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana-exposed to more than a decade of regular ivermectin treatment-have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread.Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR.This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations

Relationship between oral declaration on adherence to ivermectin treatment and parasitological indicators of onchocerciasis in an area of persistent transmission despite a decade of mass drug administration in Cameroon

BACKGROUND: Onchocerciasis control for years has been based on mass drug administration (MDA) with ivermectin (IVM). Adherence to IVM repeated treatment has recently been shown to be a confounding factor for onchocerciasis elimination precisely in rain forest areas where transmission continues and Loa loa co-exists with Onchocerca volvulus. In this study, participants’ oral declarations were used as proxy to determine the relationship between adherence to IVM treatment and parasitological indicators of onchocerciasis in the rain forest area of Cameroon with more than a decade of MDA. METHODS: Participants were recruited based on their IVM intake profile with the aid of a semi-structured questionnaire. Parasitological examinations (skin sniping and nodule palpation) were done on eligible candidates. Parasitological indicators were calculated and correlated to IVM intake profile. RESULTS: Of 2,364 people examined, 15.5 % had never taken IVM. The majority (40.4 %) had taken the drug 1–3 times while only 18 % had taken ≥ 7 times. Mf and nodule prevalence rates were still high at 47 %, 95 % CI [44.9–49.0 %] and 36.4 %, 95 % CI [34.4–38.3 %] respectively. There was a treatment-dependent reduction in microfilaria prevalence (r(s) =−0.986, P = 0.01) and intensity (r(s) =−0.96, P = 0.01). The highest mf prevalence (59.7 %) was found in the zero treatment group and the lowest (33.9 %) in the ≥ 7 times treatment group (OR = 2.8; 95 % CI [2.09–3.74]; P < 0.001). Adults with ≥ 7 times IVM intake were 2.99 times more likely to have individuals with no microfilaria compared to the zero treatment group (OR = 2.99; 95 % CI [2.19–4.08], P < 0.0001). There was no clear correlation between treatment and nodule prevalence and intensity. CONCLUSION: Adherence to ivermectin treatment is not adequate in this rain forest area where L. loa co-exists with O. volvulus. The prevalence and intensity of onchocerciasis remained high in individuals with zero IVM intake after more than a decade of MDA. Our findings show that using parasitological indicators, reduction in prevalence is IVM intake-dependent and that participants’ oral declaration of treatment adherence could be relied upon for impact studies. The findings are discussed in the context of challenges for the elimination of onchocerciasis in this rain forest area

Preliminary studies on the biting activity and transmission of Onchocerca volvulus by Simulium neavei (Diptera: Simuliidae) in Kashoya Kitomi focus, Western Uganda

Objective: To determine the biting activity and onchocerciasis transmission in Kashoya- Kitomi focus, Western Uganda. Design: Cross-sectional survey in randomly selected sites. Setting: Three districts in Western Uganda. Method: Crab trapping and examination for immature stages of Simulium neavei and full day human bait catches and dissections were conducted at three sites. Results: A total of 338 crabs were caught and out of this 372 (95.9%) were positive with immature stages of S. neavei with mean S. neavei /crab of 6.9. High biting density of S. neavei was observed in the two sites in Kabarole and Mbarara districts whereas an extremely low density was observed at a site in Bushenyi. Diurnal biting pattern revealed two peaks in the morning (09:00-10:00 hours.) and in the late afternoon (14:00- 15:00 hours.) with a mid-day lull. The infection/infective rates were 53.3/11.0%, 30.7% to 7.8% and 20.0/0% for sites in Mbarara, Kabarole and Bushenyi districts, respectively. Monthly biting rates/ Transmission potentials for Mbarara, Kabarole and Bushenyi districts were 6231/5437, 9244/2916 and 247/0. Conclusion: There was high transmission of onchocerciasis observed in Kashoya-Kitomi focus despite the ongoing ivermectin treatment. The need for improved chemotherapeutic coverage and instituting other control measures may be necessary. East African Medical Journal Vol. 81 No. 5 May 2004: 244-24

Non-adherence to community directed treatment with ivermectin for onchocerciasis control in Rungwe district, Southwest Tanzania

Background: Community directed treatment with ivermectin (CDTI) for onchocerciasis control was developed as a strategy for achieving sustained high coverage in endemic communities. This strategy for over a short period of time has radically altered the consequences of infection with Onchocerca volvulus. The present challenge is maintaining the high therapeutic coverage especially in some of the impoverished endemic countries. One of these challenges is non-adherence to ivermectin treatment and this provides compelling reason for data collection at community level. Objective: To describe the factors associated with non-adherence to CDTI. Design: Cross-sectional descriptive study. Setting: Communities participating in CDTI activities in Ndubi village, Rungwe district, southwest Tanzania. Results: A high proportion (66%) of respondents were aware of onchocerciasis, and this was more significant in males than females (X2 = 9.17; p0.939). Low knowledge levels on causes of the disease, signs and symptoms and side effects of ivermectin were attributed to inadequate health education in the communities. However, some other factors associated with non-adherence were local beliefs and the lifestyle of alcoholism. Conclusions: Factors identified to affect programme implementation and associated with nonadherence were inadequate knowledge on causes of the disease and sign/symptoms, side effects of ivermectin, local beliefs and lifestyle of alcoholism in the communities. East African Medical Journal Vol. 83(6) 2006: 326-32

From river blindness to river epilepsy: Implications for onchocerciasis elimination programmes

Current onchocerciasis elimination programmes do not include identification and management of onchocerciasis-associated epilepsy (OAE) in their strategies. Creating awareness about OAE will increase community-directed treatment with ivermectin (CDTI) adherence, particularly in areas of high prevalence, while motivating funders and stakeholders not to relent their efforts in the fight against onchocerciasis. Strengthening onchocerciasis elimination efforts should be prioritised wherever epilepsy prevalence is high in order to reduce OAE-related morbidity and mortality. In such areas, alternative treatment strategies including biannual CDTI, ground larviciding of blackfly breeding sites, and/or treatment with moxidectin should be considered. Addressing the OAE disease burden in these generally remote onchocerciasis-endemic regions confronted with poverty, weak healthcare infrastructures, and insecurity goes beyond current onchocerciasis elimination plans. New strategies with appropriate budgets are required. A morbidity management and disease prevention (MMDP) strategy, fully integrated into the health system, must be developed by multidisciplinary working groups involving neglected tropical disease (NTD) and epilepsy specialists, advocacy experts, and persons from affected communities. ‘River epilepsy’ needs to be urgently recognised and placed in the international development and NTD agendas