Prevalence of onchocerciasis and associated clinical manifestations in selected hypoendemic communities in Ghana following long-term administration of ivermectin.

BACKGROUND: Onchocerciasis is a neglected tropical disease which is still of immense major public health concern in several areas of Africa and the Americas. The disease manifests either as ocular or as dermal onchocerciasis with several symptoms including itching, nodules, skin thickening, visual impairment and blindness. Ivermectin has been an efficient microfilaricide against the causative agent of the disease (Onchocerca volvulus) but reports from some areas in Africa suggest the development of resistance to this drug. The aim of this study was to determine the prevalence of onchocerciasis and associated clinical conditions frequently associated with the disease in three endemic communities in Ghana which have been subjected to 18 to 20 rounds of mass drug administration of ivermectin. This was to help determine whether or not onchocerciasis persists in these communities. METHODS: A cross-sectional study design was adopted. Three communities (Tanfiano, Senya and Kokompe) in the Nkoranza North District of Ghana where mass drug administration of ivermectin had been ongoing for more than two decades were selected for the study. The population was randomly sampled and 114 participants recruited for the study based on the eligibility criteria. The study participants were examined for the presence of parasites and clinical manifestations of onchocerciasis following established protocols. RESULTS: The study showed that the prevalence of microfilaria in the Tanfiano, Senya, Kokompe communities were 13.2, 2.4, and 2.9%, with nodule prevalence being 5.3, 4.9 and 14.3% respectively. Females in the study communities had a higher prevalence of microfilaria carriers (5.17%) relative to males (2.44%), but this difference was not statistically significant (p = 0.2800, unpaired t test). The most frequent clinical manifestation observed in this study among all participants was dermatitis (25.4%), followed by visual impairment & nodules (7.9% each) and then by blindness (4.4%). CONCLUSION: The study showed that despite several years of mass drug administration with ivermectin, infection with onchocerciasis and the commonly associated clinical manifestations of the disease still persist in the study communities. This calls for a greater urgency for research and development aimed at discovering new or repurposed anti-filarial agents which will augment ivermectin if global onchocerciasis eradication targets are to be achieved.

High prevalence of onchocerciasis-associated epilepsy in villages in Maridi County, Republic of South Sudan: A community-based survey.

PURPOSE: To determine the prevalence and incidence of epilepsy in an onchocerciasis endemic region of South Sudan. METHODS: In May 2018, a door-to-door household survey was conducted in 8 study sites in an onchocerciasis endemic area in Maridi County. RESULTS: A total of 2511 households agreed to participate in the study, corresponding to 17,652 individuals. An epilepsy screening questionnaire identified 799 persons suspected to have epilepsy (4.5%); in 736 of the 766 persons (96.1%) seen by a clinical officer the diagnosis of epilepsy was confirmed. Adding 38 persons who were not seen but with a positive answer to a combination of screening questions, 774 persons (4.4%) had epilepsy. Epilepsy prevalence was highest in the 11-20 age group (10.5%); 66 persons with epilepsy (PWE) developed their first seizures in the year preceding the survey (annual incidence = 373.9/100.000). Neurocysticercosis cannot explain the high epilepsy prevalence since no pigs are kept in the area. Independent risk factors for epilepsy included male gender, belonging to a "permanent household" and a farming family, and living in a village bordering the Maridi River. Only 7209 (40.8%) of the population took ivermectin in 2017. CONCLUSION: A very high prevalence and incidence of epilepsy was observed in several villages in Maridi County located close to the Maridi River and the Maridi dam. Urgent action is needed to prevent children in Maridi County from developing OAE by strengthening the onchocerciasis elimination program.

Onchocerciasis prevalence, human migration and risks for onchocerciasis elimination in the Upper Mouhoun, Nakambé and Nazinon river basins in Burkina Faso.

Historically, the whole of Burkina Faso was considered to be endemic for onchocerciasis (except a small area in the far north of the country) with prevalence rates 60-80%, but all endemic areas were included in the World Health Organisation Onchocerciasis Control Programme, which operated a system of vector control by larviciding beginning in 1974. In Burkina Faso larviciding had been phased out by 1989 when it was considered that onchocerciasis had been reduced to levels below the transmission breakpoint (and any residual infections would disappear without further intervention). There was never any mass drug administration against onchocerciasis in Burkina Faso, except in the Bougouriba and Comoé river basins (from 1996 and 2011 to present respectively) because in each of these two areas there was a resurgence of infection, and in parts of the Nakambé River basin and Sissili River basin from 1992 to 1998. However, mass drug administration with ivermectin was also phased in across the whole country starting in 2000 using ivermectin against lymphatic filariasis and is currently being phased out (depending upon the epidemiological parameters). In this publication we report a new epidemiological survey for onchocerciasis which was carried out in 2014 in the Upper Mouhoun, Nakambé and Nazinon river basins in Burkina Faso to evaluate the prevalence and intensity of infection of onchocerciasis. A total of 11,195 people from 61 villages were examined across these three river basins, and onchocerciasis prevalence by skin-snip was below 5% in all villages, below 1% in 57 villages (93% of 61 villages) and zero in 47. In the 14 villages with positive skin snips, prevalence figures ranged from 0.31% to 3.50%. During the survey 31 infected individuals were found. All of them were Burkinabé, of whom 30 had a recent history of residence in Côte d'Ivoire (with a range of 0.5 to 73 microfilariae per skin-snip from two snips per person) and only one had no history of migration and presumably had an autochthonous infection (mean of 0.5 microfilariae per skin snip from two snips). According to parasitological indicators listed by the World Health Organization African Programme for Onchocerciasis Control in 2010, the situation for onchocerciasis was considered to be satisfactory in all three river basins and probably below the transmission threshold, in which case the disease should disappear naturally without the need for further intervention in the absence of continuing immigration. However, the results clearly indicate that infected persons coming from endemic zones of Côte d'Ivoire are settling in small communities which are otherwise nearly free from onchocerciasis in Burkina Faso. They are thus a source of continuing re-introduction of the parasite into the basins and could be a risk for the achievement of onchocerciasis elimination in all three basins. This would justify the continuation of periodic epidemiological surveys to monitor the possible recrudescence of the disease, and entomological (vector) surveys should be undertaken to assess and monitor the residual transmission.

Serious Neurological Adverse Events after Ivermectin-Do They Occur beyond the Indication of Onchocerciasis?

Serious neurological adverse events have been reported from large scale community-based ivermectin treatment campaigns against Onchocerciasis volvulus in Africa. The mechanism of these events has been debated in the literature, largely focusing on the role of concomitant infection with Loa loa versus the presence of mdr-1 gene variants in humans allowing ivermectin penetration into the central nervous system. A case series of serious neurological adverse events occurring with the use of ivermectin outside of the onchocerciasis indication has been identified in VigiBase, an international database of suspected adverse drug reactions. Forty-eight cases have been reported from multiple countries in which ivermectin has been prescribed for multiple indications; clinical review excluded 20 cases with more probable explanations or other exclusion criteria. Within the remaining 28 cases, there is supportive evidence for a causative role of ivermectin including presence of the drug in brain tissue in one case and recurrence of symptoms on repeated exposure in three cases. This series suggests that serious neurological adverse events observed with the use of ivermectin in the treatment of onchocerciasis may not be entirely explained by concomitant high burden loiasis infections. By comparison with the extensive post marketing experience with ivermectin in the successful treatment of parasitic infections, the number of reported cases suggests that such events are likely rare. However, elucidation of individual-level risk factors could contribute to therapeutic decisions that can minimize harms. Further investigation into the potential for drug-drug interactions and explorations of polymorphisms in the mdr-1 gene are recommended.

Spatial clustering of onchocerciasis in Bioko Island, Equatorial Guinea.

INTRODUCTION: Onchocerciasis is a chronic neglected tropical disease caused by the filarial nematode Onchocerca volvulus, which is endemic in Equatorial Guinea. The aim was to estimate the current spatial distribution of onchocerciasis, and its related factors, in Bioko Island after several years of mass drug administration and vector control activities, by using GIS technics. METHODOLOGY: The survey was carried out within the framework of a wider research project entitled "Strengthening the National Programme for Control of Onchocerciasis and other Filariasis in Equatorial Guinea". A structured questionnaire was designed to cover basic socio-demographic information and risk factors for onchocerciasis and the coordinates of household. the hydrographic network data to calculate the positive onchocerciasis rate was used. Poisson generalized linear model was used to explore the association between onchocerciasis and the following covariates: distance to the river, preventive practices, water source and household´s main source of income. Two different cluster analysis methods were used: Getis-Ord Gi statistic and SaTScan™ purely spatial statistic estimator. RESULTS: The risk of onchocerciasis was higher for those who drank water from external sources (RR 25.3) than for those who drank home tap water (RR 8.0). The clusters with z-score higher were located at the east of the island. For 5 km and 1 km distances, one significant cluster in the east was detected (RR 5.91 and RR 7.15). CONCLUSION: No environmental factors related with onchocerciasis were found, including proximity to rivers. This could be partially explained by the fact that the vector was eliminated in 2005.

Development and validation of an Onchocerca ochengi microfilarial hamster model for onchocerciasis drug screens.

BACKGROUND: Onchocerciasis, caused by the parasitic nematode, Onchocerca volvulus afflicts some 37 million people worldwide, and is the second leading infectious cause of blindness globally. The only currently recommended drug for treatment of the disease, ivermectin, is only microfilaricidal and has serious adverse effects in individuals co-infected with high loads of Loa loa microfilariae (mf), prompting the search for new and better drugs. Onchocerciasis drug discovery studies have so far been based on in vivo models using Onchocerca species which are not the closest to O. volvulus, and which may therefore, not adequately mimic the natural infection in humans. Therefore, this study was carried out to develop a better drug screening model for onchocerciasis, based on the use of cow-derived O. ochengi, the closest known relative of O. volvulus. METHODS: Mf of O. ochengi were injected subcutaneously at the nape of Syrian hamsters (Mesocricetus auratus) and BALB/c mice. The skin, and especially the earlobes of the animals were examined for mf 15-31 days after infection. For selected model validation, the hamsters were treated with ivermectin at 150 or 600 µg/kg body weight and examined 30 days after infection for mf. For L. loa studies in hamsters, isolated mf were injected intraperitoneally and animal organs were examined on day 26 for mf. RESULTS: The Syrian hamsters were found to be the more permissive to O. ochengi mf as fully viable mf were recovered from them on day 30, compared to BALB/c mice where such mf were recovered on day 15, but not 30. However, both animals were not permissive to L. loa mf even by day 15. Interestingly, more than 50 % of the total O. ochengi mf recovered were from the earlobes. The number of mf injected was directly proportional to the number recovered. Ivermectin at both concentrations tested completely eliminated the O. ochengi mf from the hamsters. CONCLUSION: This study reveals the Syrian hamster as an appropriate small animal model for screening of novel compounds against O. ochengi, the closest known relative of O. volvulus.

Oncocercosis de la mandíbula: a propósito de un caso / Onchocercosis of the jaw: about a case

Fundamento: la oncocercosis, enfermedad de Robles, es una enfermedad parasitaria crónica causada por un gusano nematodo; la filaria Onchocerca volvulus transmitida por moscas negras de la familia Simuliidae, cuyo único hospedero definitivo es el hombre. Es la segunda causa infecciosa de ceguera en el mundo.Objetivo: describir un caso de una paciente portadora de la enfermedad con un nódulo en la rama ascendente del maxilar derecho.Caso clínico: paciente africana, femenina, que acude a consulta por presentar aumento de volumen de la mandíbula derecha de varios meses de evolución y tumoración de seis centímetros de diámetro, a nivel del ángulo y rama horizontal derecha del maxilar inferior. En la citología se diagnosticó microfilariasis.Conclusiones: el parásito se trasmitió en esta enferma, como ocurre en todos los casos, por la picadura de una mosca del género Simulium, que al succionar la sangre de la paciente depositó sus larvas desencadenando la enfermedad (AU)

Background: onchocercosis, also known as Robles disease, is a chronic parasitic disease caused by a nematode worm of the genus filaria onchocerca volvulus that is transmitted by black flies of the simuliidae family and the only host of which is man. It is the second infectious cause of blindness in the world. Objective: to describe the case of a patient carrier of the disease who present a nodule in the right ascending ramus of the lower jaw.Clinical case: an African female patient who came to consultation for presenting an increase in volume of the right area of the lower jaw of some months of evolution and a tumor of six centimeters in diameter at the level of the right horizontal angle and ramus of the lower jaw. Microfilariasis was diagnosed in the cytology.Conclusions: the parasite was transmitted to the patient like it happens in all the cases, by the sting of a fly of the genus simulium that sucks the blood of the person and lays the larvae causing the disease (AU)

Evidence for suppression of Onchocerca volvulus transmission in the Oaxaca focus in Mexico.

Entomologic and serologic surveys were performed in four sentinel communities in the Oaxaca focus in southern Mexico to assess the level of transmission and exposure incidence to Onchocerca volvulus. All communities have been receiving ivermectin mass treatment twice per year since 1997. In one community, parasite DNA was detected by polymerase chain reaction-enzyme-linked immunosorbent assay in 2004 in one pool of 50 vector heads of 170 such pools (8,500 flies) examined, which indicated an estimated transmission potential of 6.7 third-stage larvae/person/year. No evidence for transmission was found in the three other communities in 13,650 flies examined. All persons in a cohort consisting of 117 children in the four communities remained serologically negative for antibodies recognizing a cocktail of recombinant antigens over a four-year period from 2001 to 2004, which indicated an exposure incidence of 0%. Taken together, these data suggest that transmission has been suppressed in the four communities.

Dracunculiasis, onchocerciasis, schistosomiasis, and trachoma.

The four diseases discussed in this chapter (dracunculiasis, onchocerciasis, schistosomiasis, and trachoma) are among the officially designated "Neglected Tropical Diseases," and each is also both the result of and a contributor to the poverty of many rural populations. To various degrees, they all have adverse effects on health, agricultural productivity, and education. The Carter Center decided to work on these health problems because of their adverse effect on the lives of poor people and the opportunity to help implement effective interventions. As a result of the global campaign spearheaded by the Carter Center since 1986, the extent of dracunculiasis has been reduced from 20 to five endemic countries and the number of cases reduced by more than 99%. We have helped administer nearly 20% of the 530 million Mectizan (ivermectin) doses for onchocerciasis, which is now being controlled throughout most of Africa, and is progressing toward elimination in the Americas. Since 1999, two Nigerian states have been using village-based health workers originally recruited to work on onchocerciasis to also deliver mass treatment and health education for schistosomiasis and lymphatic filariasis. They now also distribute vitamin A supplements and bed nets to prevent malaria and lymphatic filariasis. Ethiopia aims to eliminate blinding trachoma in the Amhara Region of that highest-endemicity country by 2012, already constructing more than 300,000 latrines and other complementary interventions. Because of the synergy between these diseases and poverty, controlling or eliminating the disease also reduces poverty and increases self-reliance.

Consequences of vector behavior in epidemiology of onchocerciasis on the Firestone Rubber Plantation in Liberia.

In the current study, we have assessed the distribution of black fly vectors and the occurrence of onchocerciasis among residents of the Firestone Rubber Plantation (FRP) in Liberia. The degree of endemicity of onchocerciasis on the FRP is correlated with the breeding of Simulium yahense on the Du River and Simulium soubrense on the Farmington River, as well as with the feeding behavior of these black fly vectors. S. yahense is highly anthropophilic and highly susceptible to Onchocerca volvulus, thus, it is apparently the primary vector of O. volvulus on the plantation. S. soubrense is predominantly zoophilic; consequently, it has a low capacity for transmitting of O. volvulus to humans. The prevalence of the disease is hyperendemic in the divisional camps near the Du River, affecting 77.6% to 94.4% of males and 64.9% to 88.9% of females. In the camps along the Farmington River, the disease is hypoendemic, affecting 26.1% to 49.2% of males and 25.6% to 35.1% of females. The mean intensity of infection in the camps near the Du River was 14.1 microfilariae (mf)/mg of skin in males and 13.7 mf/mg of skin in females. The density of microfilariae in people in the camps along the Farmington River was 4.8 mf/mg of skin in males and 1.9 mf/mg of skin in females. The age-specific infection in camps along both rivers substantially increased after the ages 21-30, reaching a maximum at ages 41-50. The mean density of mf/mg of skin in three anatomic locations (calf, hip, and shoulder) was 28.0, 24.5, and 14.1 mf/mg of skin, respectively, for those living on the Du River, and 10.2, 7.6, and 5.8 mf/mg of skin, respectively, for those on the Farmington River.

Short report: impact of ivermectin community-level treatments on elimination of adult Onchocerca volvulus when individuals receive multiple treatments per year.

A reanalysis of several published reports indicates that when community-wide biannual treatment disrupts transmission of new infection, a profound macrofilaricidal effect of ivermectin (Mectizan) occurs that is accelerated for individuals treated 4 times a year (4x/yr). The effect is particularly obvious on adult male worms and suggests that this gender is susceptible to repetitive treatment after transmission has been blocked or greatly reduced as a result of community treatment.

Local knowledge and attitudes about onchocerciasis in Oji-River local government area of Enugu State, Nigeria.

A total of 556 individuals in Agbalenyi Community of Oji-River local government area of Enugu State, Nigeria were studied using questionnaires, focus group discussions and key informant interviews to determine the socio-cultural factors affecting the transmission of onchocerciasis. The result revealed a low level of knowledge about the cause, prevention and complications of onchocerciasis. Respondents have developed a cultural system around the disease due to long exposure. The majority are aware of the disease which they recognize once their body starts itching or musculoskeletal pain develops but only 64.4, 34.0, 1.4 and 3.6%, respectively attributed chronic itching, nodules, bad vision and leopard skin to blackfly bite. Other perceived causes mentioned include ageing, the type of food eaten, farm work and 'bad blood'. Only 0.8% knew diagnosis could be made through skin snips. Neither Oji-River nor any of the river systems were associated with any of the complications of onchocerciasis. Significant differences in most socio-demographic characteristics were associated with differences in the level of knowledge about the disease.

A health club for a community school in south-eastern Nigeria: influence on adult perception of onchocerciasis and compliance with community-based ivermectin therapy.

The impact of a school health club on adult perception of onchocerciasis and compliance with ivermectin was evaluated in an onchocerciasis-endemic community in southeastern Nigeria. Venous blood was collected from each of 26, 32 and 124 randomly selected subjects during ivermectin distribution programmes in 1995 1996 and 1997 respectively. Ivermectin concentrations were measured in the samples. Data was also collected from 334 and 319 randomly selected household heads or their representatives (aged 24 to 65 years) before and after health talks by schoolchildren, using interviewer-administered questionnaires. There was an increasing number of subjects who participated in control programmes (116 in 1995, 437 in 1996 and 2055 in 1997). Compliance with ivermectin treatment was low (53.9%) in 1995 but increased dramatically (90.1%) in 1997. A significant proportion (chi2 = 108.7, df = 1, P < 0.0001) of respondents knew about onchocerciasis after health education, predominantly from health workers (64.5%) before the tests and children (92.3%) after. Knowledge and beliefs about causative agents (chi2 = 266.4, df = 5, P < 0.0001), diagnostic method (chi2 = 207.4, df = 3, P < 0.0001), prevention (chi2 = 67.0, df = 4, P < 0.0001) of onchocerciasis and the effectiveness of ivermectin (chi2 = 40.4, df = 1, P < 0.0001) also differed significantly between the periods before and after tests. The school health club increased adult knowledge about onchocerciasis and its treatment. Schoolchildren could therefore supplement the information, education and communication (IEC) aspect of health care delivery in a community through such health clubs.

[Deep onchocerciasis of the left thigh. An unusual case]. / Onchocercome profond de la cuisse gauche. A propos d'un cas isolé.

INTRODUCTION: Commonly onchocercoma has been presented as superficial and multiple nodules. When it's unique and deeply situated, its clinical diagnosis is difficult. An uncommon form of onchocercoma is reported. CASE REPORT: A 37 years old man presented a big tumor at the inferior third of the left thigh like lipoma or liposarcoma because of microcalcifications. The tumor was removed. It was a cyst containing a liquid like an "mango juice". The histological examination was performed. Degenerated microfilariae of Onchocerca volvulus was found. DISCUSSION: A big and deep onchocerma of the thigh is uncommon and diagnosis before operation is very difficult. Histological examination have eliminate filarial infections like Dracunculus medinensis and have given the right diagnosis. Radiological microcalcifications and absence of microfilariae at the parasilogical and ophthalmological examinations recall an "aged" onchocercoma. For this reason, we didn't realise a chemotherapy. CONCLUSION: This tumor in Sahel areas is very difficult to diagnose before operation. The histological examination is very important in this case. We don't use chemotherapy because this onchocercoma looks old without alive microfilariae.

Immune responsiveness and the pathogenesis of human onchocerciasis.

Prominent antibody but minimal cellular proliferative responses to parasite antigen typify the systemic immune response of patients with onchocerciasis. While components of this response are proinflammatory (and antiparasitic), the primary force driving the immune system is the need to contain or limit inflammation around microfilariae that die in the skin or elsewhere at rates up to hundreds of thousands per day. These dying parasites initiate local inflammatory reactions, with the result being "bystander" tissue damage, which cumulatively determines host pathology. Local and systemic immune mechanisms to contain inflammation (e.g., blocking antibodies, down-regulating cytokines) are prominent in infected patients, and their delineation is crucial to understanding the pathogenesis of onchocercal disease in the skin, eye, and elsewhere. The degree of pathology appears directly related to both microfilarial numbers and the intensity of proinflammatory responses to them and inversely related to the effectiveness of specific mechanisms to suppress this inflammation.