Onchocerciasis Control Programme Research Articles

Factors associated with Onchocerca volvulus transmission after 20 years of community treatment with ivermectin in savanah and forest areas in Central African Republic: A Cross Sectional Study.

The Central African Republic has endemic onchocerciasis in 20 health districts in savannah and forest areas. The country organised a mass distribution campaign of invermectin in 2023 through the National Onchocerciasis Control Programme. The objectives of this study were to identify factors of persistent Onchocerca volvulus transmission. A cross-sectional study was carried out in Bossangoa (savannah area) and Kémo (forest area) health districts. Using kelsey'formula 1600 respondents were recruited. Dependent variable is onchocerciasis status. Bivariate analysis was carried out to determine the differential risks for onchocerciasis infection, each variable being taken separately. The strength of statistical associations was measured by prevalence rates (PR) from log-binomial regression model and their 95% confidence intervals. Onchocerciasis prevalence is 26.45% in Bossangoa (95% CI = 23.76-29.14), and 14.79% (84/568) in Kémo (95% CI = 23.53-29.37). In both savannah and forest areas, the common factors incriminated in the transmission of onchocerciasis after several years of community distribution of ivermectin were: young age (PR = 2.44 (1.97-3.03), p < 0.001; 3.63 (2.32-5.70), p < 0.001 respectively), not taking ivermectin (PR = 2.31 (1.86-2.87), p < 0.001; 6.84 (4.42-10.57), p < 0.001 respectively), male sex (PR = 2.54 (2.04-3.16), p <0.001; 1.79 (1.19-2.69), p = 0.002 respectively), living near rivers and in rural areas. Despite efforts, the prevalence of onchocerciasis remained high in the 2 districts. The main factors incriminated in the persistence of transmission were failure to take ivermectin, male sex and young age. The National Onchocerciasis Control Programme needs to review its planning of activities, ensuring that the population is constantly made aware before drugs are distributed, and increasing the number of days of community-based distribution in order to improve therapeutic coverage.

Impact of ivermectin and vector control on onchocerciasis transmission in Togo: Assessing the empirical evidence on trends in infection and entomological indicators.

The World Health Organization's 2021-2030 Road Map for Neglected Tropical Diseases boosted global commitment towards the elimination of onchocerciasis, but the timeline to elimination will vary strongly between countries in Africa. To assess progress towards elimination in the Republic of Togo, we reviewed the history of control and time trends in infection. We collated all available programmatic, entomological, and epidemiological data since the initiation of the Onchocerciasis Control Programme (OCP) in Togo through different data sources. We then visualised data trends over time, to assess the impact of interventions on infection and transmission levels. Vector control was initiated by OCP from 1977 (northern and central parts of Togo) or 1988 (southern regions) up to 2002 (most areas) or 2007 ("special intervention zones" [SIZ], parts of Northern and Central Togo). Between 1988 and 1991, Togo initiated ivermectin mass drug administration (MDA) in eligible communities. The impact of vector control was high in most river basins, resulting in low annual biting rates and annual transmission potential declining to very low levels; the impact was lower in river basins designated as SIZ. Repeated, longitudinal ivermectin mass treatments have overall strongly reduced onchocerciasis transmission in Togo. Epidemiological surveys performed between 2014 and 2017 showed that the prevalence of skin microfilariae (mf) and anti-OV16 IgG4 antibodies had declined to low levels in several districts of the Centrale, Plateaux, and Maritime region. Yet, relatively high mf prevalences (between 5.0% and 32.7%) were still found in other districts during the same period, particularly along the Kéran, Mô and Ôti river basins (SIZ areas). Trends in infection prevalence and intensity show that onchocerciasis levels have dropped greatly over time in most areas. This demonstrates the large impact of long-term and wide-scale interventions, and suggest that several districts of Togo are approaching elimination.

Progress towards elimination of onchocerciasis in the Region du Sud-Ouest of Burkina Faso which was previously subject to a recrudescence event after vector control.

The Sud-Ouest region of Burkina Faso (especially the Bougouriba valley) has been historically problematic with respect to onchocerciasis control, with a recrudescence of infections after vector control carried out the WHO Onchocerciasis Control Programme was halted in 1989. After 1996, mass drug administration of ivermectin was instigated to control the recrudescence so that it would no longer constitute a public health problem. However, in 2010 WHO changed its recommended policy from control to elimination, and in 2013 biannual Community-Directed Treatment with Ivermectin (CDTI) was instigated. Epidemiological surveys were carried-out in 2011 and 2018 to determine whether CDTI was producing a decline in infection levels and progress towards elimination. A cross-sectional study was conducted across 20 villages in four health districts in 2011 and 29 villages in 2018. Individuals aged five years and above were examined by skin-snip, and the prevalence and microfilarial load was determined for each village. In 2011, 75% of villages had some infections and 20% had prevalences >5%, with a mean prevalence across all villages of 2.63% (range 0.0-9.7%), and community microfilarial load ranging from 0 to 0.25 microfilariae per biopsy. In 2018, nine villages (= 31% of total) had some infections, with prevalences ranging from 0.41% to 3.54%, and a mean prevalence across all villages of 0.37%. Community microfilarial load ranged from 0 to 0.1. Amongst those people found to be microfilarial positive, 87% had a history of migration. The endemicity of onchocerciasis infection in the Sud-Ouest region has declined to low levels and seems to be progressing towards elimination. Our findings indicated that biannual CDTI is having good effect, but it should continue for a number of years to ensure elimination of transmission. However, progress towards elimination has a troublesome history in this region, and it would be advisable to select more sentinel villages to have confidence in any future epidemiological and entomological surveys, especially Stop-MDA surveys. With positive individuals migrating between countries, cross-border collaboration needs more attention to ensure effective treatment for onchocerciasis elimination.

Management of onchocerciasis among adolescents in nkwanta north district of Ghana: Qualitative study of adolescents' perception, community and health system support.

Onchocerciasis affects the quality of life to a greater extent among affected individuals. The World Health Organization (WHO)'s Onchocerciasis Control Program (OCP) has effectively reduced the prevalence of onchocerciasis by interrupting the transmission of the parasite and by mass population treatment in the regions at risk of the disease. Despite the successful reduction of the prevalence of onchocerciasis by WHO, the socioeconomic burden resulting from the disabilities caused by onchocerciasis are still immense. This study sought to explore the adolescents' perception regarding the management of onchocerciasis, community and health system support in Nkwanta North District of Ghana. This study adopted a qualitative phenomenological design and exploratory, descriptive qualitative approach. An in-depth interview guide was developed to collect data for the study. One-on-one interview was conducted. Data collected from 16 onchocerciasis adolescent patients were analysed thematically using ATLAS.ti v7.5.7. Quotes from the participants were presented verbatim to substantiate the themes realised. Most of the 12 participants (75.0%) were aged 15-18 years old. It was noted that 6(37.50%) of participants were in Junior High School (JHS), while 4(25.0%) were in Senior High School (SHS). It was noted that community members have diverse understandings and perceptions of onchocerciasis, including beliefs that Onchocerciasis is a serious disease that can cause blindness; it is caused by the consumption of some types of food products or stressful work. Adolescents believed that onchocerciasis was caused by insect bite blood infection, poor environmental hygiene, sun or could have been inherited from parents. Ivermectin treatment was noted by adolescents to have helped relieve the symptoms of ochocerciasis they were experiencing. However, the adolescents indicated that they had experienced some side effects, including fever, headache, body itching, rushes, swollen body and blurred vision from the drug. Inadequate education and communication about onchocerciasis resulted in diverse and erroneous meanings of onchocerciasis among community members. Our research recognises that community and health system supports is very important in the effective management of Onchocerciasis, contributing to the attainment of Sustainable Development Goal (SDG) 3.3, which is targeted at ending the epidemic of NTDs like onchocerciasis by 2030.

Status of Onchocerciasis Elimination in Gabon and Challenges: A Systematic Review.

Control and treatment programs (CDTI) have been set up nationally in all endemic countries to overcome the impact of onchocerciasis on the affected populations. However, Gabon must still succeed in setting up real onchocerciasis control programs. Here, various database articles have been used to provide the scientific community with a summary document showing the mapping of this disease in Gabon. The articles dealing with onchocerciasis, animal reservoirs, surveillance, and elimination were analyzed. Results showed that little research has been performed. Most studies are concentrated in one region (The area of Lastourville). In addition, we observed that the distribution of the disease varies significantly across the country. Indeed, specific environments present a hyper-endemicity of the disease, while others are meso and hypo-endemic. So, we found some departments with a prevalence ranging from 0% to over 20%; within them, villages had infection levels comprising 10% to 60%, indicating potential hotspots. Vectors activities were studied in some areas. This paper showed the challenges encountered in the country to eliminate this disease. One solution is a deeper understanding of the disease's bioecology to establish effective health policies to eliminate onchocerciasis in Gabon effectively.

Impact of ivermectin mass drug administration on burden of soil-transmitted helminths in onchocerciasis control and elimination programs, Yeki district, southwest Ethiopia.

Community-directed treatment with ivermectin (CDTi) is the primary strategy employed to control and eliminate human onchocerciasis in Ethiopia. After long-term mass distribution for onchocerciasis, ivermectin is expected to have additional benefits beyond the envisioned targets by reducing the burden of other co-endemic parasitic infections as to STHs. To date, studies focused on the collateral impact of CDTi on STH in Ethiopia are scanty. Two community-based cross-sectional surveys (baseline in 1997 and post-CDTi in 2017) were conducted to evaluate the impact of long-term CDTi employed to control and eliminate onchocerciasis on the burden of STH infections in Yeki district of southwest Ethiopia. Stool samples were collected and examined using Ritchie`s concentration and Kato-Katz techniques in the baseline and current study, respectively. Overall, 188(38.3%, 95% Confidence interval (CI) 34.1–42.7%) individuals were positive at least for any of the STH species from 491 study participants in the post-CDTi. The prevalence of A. lumbricoides, hookworms, and T. trichiura was 11.2% (95% CI 8.7–14.3%), 16.3% (95% CI 13.3–19.8%), and 29.9% (95% CI 26.1–34.1%), respectively. Individuals aged 5–9 years had a significantly higher prevalence of A. lumbricoides (Adjusted odds ratio (AOR) 6.5, 95% CI 1.7–25.4), T. trichuria (AOR 8, 95% CI 2.6–25.1), and any STH infection (AOR 5, 95% CI 1.7–14.7) than those of ≥ 51 years. Also, significantly higher prevalences of T. trichuria infection were observed in individuals aged 10–14 years (AOR 4.1, 95% CI 1.7–9.9), 15–20 years (AOR 3.1, 95% CI 1.2–8.1), 21–30 years (AOR 2.4, 95% CI 1.1–5.5), and 31–40 years (AOR 3.2, 95% CI 1.3–7.5) compared with those of ≥ 51 years. The prevalence of A. lumbricoides was significantly higher in males (AOR 0.5, 95% CI 0.3–0.9). Of the 491 study participants, only data from 400 individuals who had not been involved in a mass drug administration (MDA) with other STH anthelmintics were considered in the comparative analysis. Before CDTi, the prevalence of A. lumbricoides, T. trichiura, hookworm, and any STH infection was 47.1% (95% CI 41.6–52.7%), 3.3% (95% CI 1.8–5.9%), 37.9% (95% CI 32.7–43.5%), and 58.8% (95% CI 53.2–64.1%), respectively. Long-term CDTi considerably reduced the prevalences of A. lumbricoides and hookworm by 76.2% and 56.9%, respectively (p < 0.001). Nonetheless, CDTi did not affect the prevalence of T. trichiura infection and, in contrast, it was significantly higher in the current study (P < 0.001). Overall post-CDTi prevalence of any STH infection was considerably lower than reported in the baseline (p < 0.001). It is evidenced that long-term CDTi for onchocerciasis control and elimination had additional benefits by reducing the prevalence of STH infections specifically of A. lumbricoides and hookworm, but had no impact on infections with T. trichuria. Our finding of additional health benefits of large-scale ivermectin administration taking it will aid to increase positive engagement and sustain participation of communities during MDA campaigns, and strengthen governmental and non-governmental organizations (NGOs) support for the undergoing national onchocerciasis elimination program.

Disability and its determinants among individuals with onchocerciasis in Southeast Nigeria: a cross-sectional study.

Introductionalthough onchocerciasis is rarely a life-threatening disease, it causes chronic morbidity which ultimately leads to disability due to late detection and treatment of the infected people. Disability in Onchocerciasis results in activity limitation and social exclusion of the affected individuals through stigma. This study aimed at assessing the level of disability and its determinants among persons with onchocerciasis.Methodsmulti-stage sampling technique was used to recruit 340 respondents from the randomly selected wards. Disability was assessed using WHO Disability Assessment Schedule 2.0 (WHODAS 2.0) tool. Chi-square test and multivariate analysis using binary logistic regression were used to determine factors associated with disability. The level of statistical significance was determined by a p-value of < 0.05.Resultsthe highest proportion (35.6%) of the respondents was 55 years and above with a mean age of 46.8±17.5. About three-quarters (76.2%) of them had some form of disability and the disability domains mainly affected were participation in community activities (61.8%) and getting along with other people (54.1%) while the least affected were self-care (26.2%) and life activities including domestic responsibilities (45.0%). The Predictor of disability included being ≥48 years old, (AOR=0.2; 95%CI: 0.1-0.4).Conclusionmost people with onchocerciasis experience some form of disability and the major determinant for disability is being in the older age group. Thus, there is a need for stakeholders in the onchocerciasis control program to formulate and implement disability screening programs in the communities for early detection of onchocerciasis-associated disability, especially among the older age group.

The impact of ivermectin on onchocerciasis in villages co-endemic for lymphatic filariasis in an area of onchocerciasis recrudescence in Burkina Faso.

In Burkina Faso, onchocerciasis was no longer a public health problem when the WHO Onchocerciasis Control Programme in West Africa closed at the end in 2002. However, epidemiological surveillance carried out from November 2010 to February of 2011, showed a recrudescence of infection in the Cascades Region. This finding was made at a time when ivermectin, a drug recommended for the treatment of both onchocerciasis and lymphatic filariasis, had been distributed in this area since 2004 for the elimination of lymphatic filariasis. It was surprising that ivermectin distributed for treating lymphatic filariasis had not prevented the recrudescence of onchocerciasis. Faced with this situation, the aim of our study was to evaluate the effectiveness of ivermectin on the onchocerciasis parasite. The percentage reduction in microfilarial load after treatment with ivermectin was used as a proxy measure for assessing possible resistance. A cohort study was carried out with 130 individuals who had tested positive for microfilariae of Onchocerca volvulus in 2010 using microscopic examination of skin-snip biopsies from five endemic villages. Subjects were followed from July 2011 to June 2012. The microfilarial load of each individual was enumerated by skin-snip biopsy in 2010, prior to the first ivermectin treatment against onchocerciasis under community guidelines. All individuals received two ivermectin treatments six months apart. In 2012, the microfilarial loads were determined again, six months after the second round of ivermectin and the reductions in parasite loads were calculated to measure the impact of the drug. The percentage reduction of the microfilarial loads ranged from 87% to 98% in the villages. In all villages, there was a statistically significant difference between the average microfilarial loads in 2010 and 2012. The level of reduction of microfilarial loads suggests that ivermectin is effective against the recrudescent population of O. volvulus in Cascades Region of Burkina Faso. Further investigations would be necessary to determine the causes of the recrudescence of onchocerciasis. (For French language abstract, see S1 Alternative Language —Translation of the into French by the authors.)

The Mbam drainage system and onchocerciasis transmission post ivermectin mass drug administration (MDA) campaign, Cameroon.

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. 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. 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. 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.

Onchocerciasis control in Ghana (1974\u20132016)

BackgroundThe control of onchocerciasis in Ghana started in 1974 under the auspices of the Onchocerciasis Control Programme (OCP). Between 1974 and 2002, a combination of approaches including vector control, mobile community ivermectin treatment, and community-directed treatment with ivermectin (CDTI) were employed. From 1997, CDTI became the main control strategy employed by the Ghana OCP (GOCP). This review was undertaken to assess the impact of the control interventions on onchocerciasis in Ghana between 1974 and 2016, since which time the focus has changed from control to elimination.MethodsIn this paper, we review programme data from 1974 to 2016 to assess the impact of control activities on prevalence indicators of onchocerciasis. This review includes an evaluation of CDTI implementation, microfilaria (Mf) prevalence assessments and rapid epidemiological mapping of onchocerciasis results.ResultsThis review indicates that the control of onchocerciasis in Ghana has been very successful, with a significant decrease in the prevalence of infection from 69.13% [95% confidence interval) CI 60.24–78.01] in 1975 to 0.72% (95% CI 0.19–1.26) in 2015. Similarly, the mean community Mf load decreased from 14.48 MF/skin snip in 1975 to 0.07 MF/skin snip (95% CI 0.00–0.19) in 2015. Between 1997 and 2016, the therapeutic coverage increased from 58.50 to 83.80%, with nearly 100 million ivermectin tablets distributed.ConclusionsDespite the significant reduction in the prevalence of onchocerciasis in Ghana, there are still communities with MF prevalence above 1%. As the focus of the GOCP has changed from the control of onchocerciasis to its elimination, both guidance and financial support are required to ensure that the latter goal is met.Graphical

Taking the strain out of onchocerciasis? A reanalysis of blindness and transmission data does not support the existence of a savannah blinding strain of onchocerciasis in West Africa.

Onchocerciasis (also known as 'river blindness'), is a neglected tropical disease (NTD) caused by the (Simulium-transmitted) filarial nematode Onchocerca volvulus. The occurrence of 'blinding' (savannah) and non-blinding (forest) parasite strains and the existence of corresponding, locally adapted Onchocerca-Simulium complexes were postulated to explain greater blindness prevalence in savannah than in forest foci. As a result, the World Health Organization (WHO) Onchocerciasis Control Programme in West Africa (OCP) focused anti-vectorial and anti-parasitic interventions in savannah endemic areas. In this paper, village-level data on blindness prevalence, microfilarial prevalence, and transmission intensity (measured by the annual transmission potential, the number of infective, L3, larvae per person per year) were extracted from 16 West-Central Africa-based publications, and analysed according to habitat (forest, forest-savannah mosaic, savannah) to test the dichotomous strain hypothesis in relation to blindness. When adjusting for sample size, there were no statistically significant differences in blindness prevalence between the habitats (one-way ANOVA, P=0.68, mean prevalence for forest=1.76±0.37 (SE); mosaic=1.49±0.38; savannah=1.89±0.26). The well-known relationship between blindness prevalence and annual transmission potential for savannah habitats was confirmed and shown to hold for (but not to be statistically different from) forest foci (excluding data from southern Côte d'Ivoire, in which blindness prevalence was significantly lower than in other West African forest communities, but which had been the focus of studies leading to the strain-blindness hypothesis that was accepted by OCP planners). We conclude that the evidence for a savannah blinding onchocerciasis strain in simple contrast with a non-blinding forest strain is equivocal. A re-appraisal of the strain hypothesis to explain patterns of ocular disease is needed to improve understanding of onchocerciasis epidemiology and disease burden estimates in the light of the WHO 2030 goals for onchocerciasis.

Meta-analysis of epilepsy prevalence in West Africa and its relationship with onchocerciasis endemicity and control.

BackgroundA high prevalence and incidence of epilepsy has been reported in onchocerciasis-endemic regions in Central and East Africa. There is compelling epidemiological evidence suggesting that this high burden is caused by onchocerciasis-associated epilepsy (OAE). We hypothesized that OAE had also occured in West African onchocerciasis foci.MethodsWe searched PubMed, the African Journals Online platform and grey literature for population-based epilepsy studies in West African countries. Epilepsy and onchocerciasis prevalence data were extracted. The pre-control onchocerciasis endemicity in the study sites was estimated from historical data of onchocerciasis control programmes. The prevalence of epilepsy in different sites was analysed, taking into account onchocerciasis endemicity and the duration of control.ResultsThe pooled prevalence of epilepsy in the West African study sites was 13.14 per 1000 (95% confidence interval 11.28–15.00). Higher pre-control endemicity and a shorter duration of onchocerciasis control were both associated with increased epilepsy prevalence (p<0.001). Two studies in Ivory Coast that provided detailed descriptions of persons with epilepsy in onchocerciasis-endemic settings revealed that most of them had features of OAE (73.7% and 83.3%, respectively).ConclusionsOur findings suggest that before and during the early years of implementing onchocerciasis control in West Africa, high onchocerciasis endemicity resulted in a high prevalence of OAE and that subsequent control efforts significantly reduced the prevalence of OAE.

Onchocerciasis: status and progress towards elimination

Abstract Craw craw was first described almost 150 years ago. Since then considerable progress has been made in understanding the Onchocerca volvulus life cycle, its effects on the host (blindness, skin disease and epilepsy) and potential control measures. Early attempts were aimed at controlling the black fly ( Simulium ) that transmits the disease. This included the early use of DDT in some isolated foci in East Africa. This was followed in the 1970s by the Onchocerciasis Control Programme (OCP) of West Africa using other safer insecticides. In 1987, MSD (known as Merck &amp; Co Inc. in the USA and Canada) announced the donation of Mectizan ® (ivermectin MSD) as long as was necessary for onchocerciasis control. This began a new chapter in the control of the disease including the creation of the African Programme for Onchocerciasis Control (APOC) and the Onchocerciasis Elimination Programme for the Americas (OEPA). In the Americas, four countries have now been verified free of transmission of the disease by the World Health Organisation. In Africa where foci are considerably larger, APOC with its partners has succeeded in developing a control programme covering virtually all areas where the prevalence of the disease can cause serious effects. In some disease foci in Africa, elimination of transmission has been achieved. Following surveys on the Mali Senegal border, there was a move in 2009 to change the paradigm from control to elimination. Development has been slow but by 2030, there is hope that most countries will have stopped treatment and others will have completed post-treatment surveillance surveys although some foci in conflict areas will remain.

Genetic Diversity of Simulium damnosum complex Onchocerciasis Vector and its Influence on Entomological Monitoring in the West of Côte d'Ivoire

In West Africa, Onchocerca volvulus, the causative pathogen of human onchocerciasis, is transmitted by sibling species of the Simulium damnosum complex. Little is known about blackfly intraspecific variability and its consequences on vectorial capacity in Cote d’Ivoire. This study reports the use of microsatellite markers to study the genetic profile and evaluate the gene flow between populations of S. damnosum s.l from three (3) different epidemiological facies in western Cote d’Ivoire, fifteen years after the end of onchocerciasis control program. Adult flies were collected on human attractants from 07 : 00 to 18 : 00 hours for three consecutive days by site, from December 2016 to October 2017. Four (4) microsatellite loci were used to characterize individuals from these populations. The four (4) loci were polymorphic with 13.25 alleles per locus. Two (2) specific alleles (190 bp and 290 bp), were reveal abundant with respective frequencies of 0.46 % and 0.58 %. Asignificant heterozygosity deficiency and low genetic differentiation (FST = 0.046, P = 0.024) have been observed for all the populations. The genetic analysis showed significant deviation from Hardy-Weinberg and significant heterozygosity deficiencies. Then, the great interspecific variability would be a general characteristic in S. damnosum s.l. At last, a probable evolution of the invasive strains of S. damnosum would have occurred in these localities. This study has shown significant deviation from Hardy-Weinberg and significant heterozygosity deficiencies in the populations of the three localities. The loci give independent estimate genetic parameters. The H3-4 locus to a low genetic differentiation between the populations.

Onchocerciasis in Burkina Faso: a Re-Emerging Vector-Borne Endemic Disease

Burkina Faso, like other countries, reported a focal interruption of onchocerciasis transmission and was thus placed under post-therapeutic surveillance. However, the country seems to be experiencing a resurgence of the disease according to recent surveys at certain sentinel sites and data from various surveys. The aim of our study is to take stock of the evolution of the current epidemiological situation of onchocerciasis in Burkina Faso. For data collection, in addition to the scientific articles, we have used data from different epidemiological and entomological surveys conducted by the National Program for the Control of Neglected Tropical Diseases (PNLMTN) through its onchocerciasis elimination unit in Burkina Faso. Prior to implementation of the Onchocerciasis Control Program in West Africa (OCP), Burkina Faso had onchocerciasis prevalence between 60% and 80%. In 2002, the maximum prevalence dropped to 15%. However, in 2010 and 2011, epidemiological surveys indicated that some villages in the Comoé River basin had prevalence rate ranging from 0.7% to 71%. Thirteen (13) villages had prevalence rates above the tolerable threshold of 5%. Despite the implementation of the community-directed treatment with ivermectin (CDTI) since 2011, recent surveys show a tendency for a recrudescence of the disease in some sites, yet covered by the TIDC. This suggests that the elimination of onchocerciasis requires the integration of new control strategies. Thus, an essential condition for the elimination of onchocerciasis is the analysis of the situation in each focus in order to define the most cost-effective strategy for permanently interrupting the transmission of the parasite. National onchocerciasis elimination committees put in place will play a key role in determining the best strategy.

Comparison of School-Based and Community-Wide Mass Drug Administration for Schistosomiasis Control in an Area of Western Kenya with High Initial Schistosoma mansoni Infection Prevalence: A Cluster Randomized Trial.

.We conducted a cluster randomized trial comparing the target population and timing of mass drug administration (MDA) with praziquantel for control of schistosomiasis in villages in western Kenya with high initial prevalence (> 25%) according to a harmonized protocol developed by the Schistosomiasis Consortium for Operational Research and Evaluation. A total of 150 villages were randomized into six treatment arms (25 villages per arm), were assessed at baseline, and received two or four rounds of MDA using community-wide (CWT) or school-based (SBT) treatment over 4 years. In the fifth year, a final evaluation was conducted. The primary outcomes were prevalence and intensity of Schistosoma mansoni infections in children aged 9–12 years, each year their village received MDA. Baseline and year 5 assessments of first-year students and adults were also performed. Using Poisson and negative binomial regression with generalized estimating equations, we found similar effects of CWT and SBT MDA treatment strategies in children aged 9–12 years: significant reductions of prevalence of infection in all arms and of heavy-intensity (≥ 400 eggs/gram) infections in most arms but no significant differences between arms. Combined arms of villages that received four rounds of treatment had greater reduction than villages in arms that only received two rounds of treatment. Surprisingly, we also found benefits of SBT for first-year primary students and adults, who never received treatment in those arms. Our data support the use of annual SBT for control programs when coupled with attention to infections in younger children and occasional treatment of adults.

Barriers to the National Onchocerciasis Control Programme at operational level in Cameroon: a qualitative assessment of stakeholders\u2019 views

BackgroundThe global burden of onchocerciasis is the heaviest in sub-Saharan Africa. Studies have shown the importance of the role of Community-Directed Distributors (CDDs) and nurses in onchocerciasis control, but little is known about their experience in implementing onchocerciasis control programmes. Our aim was to document the barriers that CDDs and local health administrators face in implementing onchocerciasis control activities.MethodsWe conducted a qualitative survey consisting of 16 in-depth interviews and 8 focus group discussions (FGDs) across three health districts of Cameroon. We interviewed a total of 9 local health officials at the district and Health Area levels, and 7 CDDs. Eight FGDs were conducted with CDDs and Health Committee members.ResultsThe major barriers to the implementation of Community Directed Treatment with Ivermectin that we identified were linked and interrelated. Examples of these barriers included: contextual factors (geographical and cultural background), top-to-bottom planning, insufficient human and material resources, and lack of transparency in the management of the programme’s funds.ConclusionsThe CDTI at operational level still faces many obstacles which negatively affect therapeutic coverages. This can lead to the non-adhesion of the communities to the programme, consequently jeopardizing the sustainability of the onchocerciasis elimination programme. We recommend that the national programme planners put in place a transparent management and planning system for onchocerciasis elimination activities, with better communication with local programme stakeholders.

Optimisation of &lt;i&gt;Bacillus thuringiensis&lt;/i&gt; var. &lt;i&gt;israelensis&lt;/i&gt; (Vectobac&lt;sup&gt;®&lt;/sup&gt;) applications for the blackfly control programme on the Orange River, South Africa

The Orange River, South Africa's largest river, is a critical water resource for the country. In spite of the clear economic benefits of regulating river flows through a series of impoundments, one of the significant undesirable ecological consequences of this regulation has been the regular outbreaks of the pest blackfly species Simulium chutteri and S. damnosum s.l. (Diptera: Simuliidae). The current control programme, carried out by the South African National Department of Agriculture, uses regular applications, by helicopter, of the target-specific bacterial larvicide Bacillus thuringiensis var. israelensis. While cost-benefit analyses show significant benefits to the control programme, benefits could potentially be further increased through applying smaller volumes of larvicide in an optimised manner, which incorporates upstream residual amounts of pesticide through downstream carry. Using an optimisation technique applied in the West African Onchocerciasis Control Programme, to a 136 km stretch of the Orange River which includes 31 blackfly breeding sites, we demonstrate that 28.5% less larvicide could be used to potentially achieve the same control of blackfly. This translates into potential annual savings of between R540 000 and R1 800 000. A comparison of larvicide volumes estimated using traditional vs. optimised approaches at different discharges, illustrates that the savings on optimisation decline linearly with increasing flow volumes. Larvicide applications at the lowest discharge considered (40 m3·s-1) showed the greatest benefits from optimisations, with benefits remaining but decreasing to a theoretical 30% up to median flows of 100 m3·s-1. Given that almost 70% of flows in July are less than 100 m3·s-1, we suggest that an optimised approach is appropriate for the Orange River Blackfly Control Programme, particularly for flow volumes of less than 100 m3·s-1. We recommend that trials be undertaken over two reaches of the Orange River, one using the traditional approach, and another using the optimised approach, to test the efficacy of using optimised volumes of B.t.i.

Pierre Richet (1904-1983), fighting onchocerciasis and totalitarism.

While Eugène Jamot's name is associated with the combat against sleeping sickness, Pierre Richet is permanently linked to the battle against river blindness, which he first reported in 1936 in two neighboring households in Garango (Burkina Faso). Onchocerciasis remained a continuous interest, through his last article "The OCCGE and Onchocerciasis", written in 1983. Nonetheless over the course of these five decades, Richet's trajectory was far from that of a specialist dedicating his life to a single disease. After a decade essentially spent fighting trypanosomiasis, came a decade of war in which the specialist in endemism joined the Free French Army and put his organizational know-how at General Lerclerc's disposal, from Morocco to Indochina, via Germany. On his return to Africa in 1953, he extended the principle of mobile teams to the other major endemic diseases accessible to treatment and to vaccines. Richet organized first the combat against leprosy and launched vaccination programs. In 1955, he returned to the battle against onchocerciasis and deployed the first large-scale insecticide program in Chad. The intermediate term failure of this prototype fermented his scientific, interdisciplinary, and organizational thought, which flourished at Bobo-Dioulasso. At the dawn of the independence of French-speaking African countries, and against the political tides of the time, he obtained in 1960 the creation of a supranational organization, the OCCGE, common to 8 countries of West Africa, and he headed it for a decade. Drawing lessons from the past and in the absence of effective pharmaceutical treatment, Richet the physician played the entomological card with one hand, with technical support from Orstom (IRD); this detailed work enabled the development of a strategy. With the other hand, he played the multilateral card, which led in 1974 to the launching of the extraordinary Onchocerciasis Control Program (OCP). If it is Jamot who awakened Africa, Richet is the person who restored its view but also millions of hectares of cultivable land.

Assessment of Knowledge, Attitude and Practices of Onchocerciasis Prevention and Control in Becho Woreda, Illu Ababora, Oromia Regional State, South West Ethiopia

Background: Onchocerciasis is a filarial disease caused by Onchocerca volvulus and transmitted by a black fly. Onchocerciasis is a killer of livestock and wild animals, so its prevention and control are helpful for health planners and health educators providing basic information to focus on its prevention and control. Objective: The objective of this study was to assess the knowledge, attitude and practice of onchocerciasis prevention and control in Becho woreda, Illu Ababora, Oromia regional state, South West Ethiopia in the year 2018. Methods : Community-based cross-sectional study design was employed through systematic sampling technique. The data were collected from every seven houses after randomly selecting the first house from 1 to 7 until calculated sample size reached. A total of 322 households were included in the study. A structured questionnaire was used for gathering the data. Data were coded, entered and analyzed by using SPSS version 16. Results : Out of 322 respondents, 177 (59%) were male and 123 (41%) were female. The response rate was 300 (93%) and the age of respondents ranged from 18 to 60 years; the majority was 26–45 years of age with the mean age of 31 years. The study showed that only 59 (19.7%) of the total respondents knew the right cause of onchocerciasis, and majority of them 233 (77.7%) responded that black fly is the cause of the disease. Of the study population, 66% had poor knowledge, 4.7% had unfavorable attitude, and 77.3% of them had unsafe practice. Conclusion: As in the result, the study undergone on onchocerciasis prevention and control programme showed that; of the study population, 66% had poor knowledge, 4.7% had unfavorable attitude, and 77.3% of them had unsafe practice. Keywords: Onchocerciasis, Becho woreda, Onchocerca volvulus Cite this Article Masresha Leta Serbesa. Assessment of Knowledge, Attitude and Practices of Onchocerciasis Prevention and Control in Becho Woreda, Illu Ababora, Oromia Regional State, South West Ethiopia. Research & Reviews: Journal of Medicine . 2019; 9(2): 18–24p