Onchocerciasis in Ibarapa, Western State, Nigeria

Impact of five annual rounds of mass drug administration with ivermectin on onchocerciasis in Sierra Leone

BACKGROUND

Onchocerciasis is endemic in 12 of the 14 health districts of Sierra Leone. Good treatment coverage of community-directed treatment with ivermectin was achieved between 2005 and 2009 after the 11-year civil conflict. Sentinel site surveys were conducted in 2010 to evaluate the impact of five annual rounds of ivermectin distribution.

METHODS

In total, 39 sentinel villages from hyper- and meso-endemic areas across the 12 endemic districts were surveyed using skin snips in 2010. Results were analyzed and compared with the baseline data from the same 39 villages.

RESULTS

The average microfilaridermia (MF) prevalence across 39 sentinel villages was 53.10% at baseline. The MF prevalence was higher in older age groups, with the lowest in the age group of 1-9 years (11.00%) and the highest in the age group of 40-49 years (82.31%). Overall mean MF density among the positives was 28.87 microfilariae (mf)/snip, increasing with age with the lowest in the age group of 1-9 years and the highest in the age group of 40-49 years. Males had higher MF prevalence and density than females. In 2010 after five rounds of mass drug administration, the overall MF prevalence decreased by 60.26% from 53.10% to 21.10%; the overall mean MF density among the positives decreased by 71.29% from 28.87 mf/snip to 8.29 mf/snip; and the overall mean MF density among all persons examined decreased by 88.58% from 15.33 mf/snip to 1.75 mf/snip. Ten of 12 endemic districts had > 50% reduction in MF prevalence. Eleven of 12 districts had ≥50% reduction in mean MF density among the positives.

CONCLUSIONS

A significant reduction of onchocerciasis MF prevalence and mean density was recorded in all 12 districts of Sierra Leone after five annual MDAs with effective treatment coverage. The results suggested that the onchocerciasis elimination programme in Sierra Leone was on course to reach the objective of eliminating onchocerciasis in the country by the year 2025. Annual MDA with ivermectin should continue in all 12 districts and further evaluations are needed across the country to assist the NTDP with programme decision making.

Pre-control relationship of onchocercal skin disease with onchocercal infection in Guinea Savanna, Northern Nigeria

Background

Onchocerca volvulus infection can result in blindness, itching and skin lesions. Previous research concentrated on blindness.

Methods

A clinical classification system of the cutaneous changes in onchocerciasis was used for the first time in this study within the context of an early ivermectin drug trial in the savanna region of Kaduna State, northern Nigeria. Skin examinations were performed in 6,790 individuals aged 5+ years in endemic communities and 1,343 individuals in nonendemic communities.

Results / Discussion

There was increased risk for all forms of onchocercal skin disease in endemic communities with the most common finding being the presence of nodules (1,438 individuals, 21.2%), followed by atrophy (367, 6.1% of those < 50 years), acute papular onchodermatitis, APOD (233, 3.4%), depigmentation (216, 3.2%) and chronic papular onchodermatitis, CPOD (155, 2.3%). A further 645 individuals (9.5%) complained of pruritus but had completely normal skin. APOD was more common in males whereas atrophy, hanging groin and nodules were more common in females. After controlling for age and sex, microfilarial positivity was a risk factor for CPOD, depigmentation, hanging groin and nodules (OR 1.54, p = 0.046; OR 2.29, p = 0.002; OR 2.18, p = 0.002 and OR 3.80, p <0.001 respectively). Comparable results were found using presence of nodules as the marker for infection. Microfilarial load showed similar, though weaker, results. A total of 2621(38.6%) endemic residents had itching with normal skin, or had one or more types of onchocercal skin disease including nodules, which may be considered as a composite index of the overall prevalence of onchocercal skin disease.

Conclusion

Significant levels of onchocercal skin disease were documented in this savanna area, which subsequently resulted in a reassessment of the true burden of skin disease in onchocerciasis. This paper represents the first detailed report of the association of onchocercal skin disease with markers for onchocercal infection.

Onchocerciasis is a tropical parasitic infection caused by the nematode worm Onchocerca volvulus. The disease mainly occurs across tropical Africa and infection can result in blindness, debilitating itching and a variety of skin changes. Initial research concentrated mainly on the problem of blindness. A number of studies on onchocercal skin disease were performed but were difficult to interpret and compare because of the use of inconsistent terminology. Within the setting of one of the early trials of ivermectin in a savanna area of northern Nigeria, where there were known high rates of onchocercal blindness, we used a novel clinical classification of the skin changes in onchocerciasis. We identified significant levels of itching and various forms of onchocercal skin disease within these endemic communities. A positive skin-snip result proved to be a significant risk factor for the presence of chronic papular onchodermatitis (CPOD), depigmentation, hanging groin and onchocercal nodules. Comparable results were found when the presence of nodules was used as the marker for infection and similar, though weaker odds ratios were found with microfilarial load per se. The findings triggered a reassessment of the true burden of skin disease in onchocerciasis. It is the first detailed report of the association between onchocercal skin disease and markers of infection.

Five-Year Knowledge Retention by Volunteer Primary Health Workers in Western Nigeria

A volunteer primary health worker (PHW) must acquire a basic knowledge of preventive and curative medicine to approach his community with authority. Knowledge gained during training must be retained as a foundation for village level action. This study is a follow-up survey of knowledge among PHWs in a Western Nigerian town five years after training. The same end of course test was administered and results compared with age, sex, level of education and level of activity in PHC programming. The follow-up test scores showed an expected decrease in information retained. The only demographic factor consistently associated with knowledge after training and at follow-up was level of education. In addition level of PHC activity (e.g., attending PHW meetings, maintaining a village drug box) was associated with greater knowledge, but was also positively related to level of education. It is therefore recommended that PHC programs ideally recruit PHWs with vernacular literacy, but where this is not possible, extra effort must be put into close follow-up supervision of trainees.

Testing Alternative Record Keeping Formats Not Requiring Literacy Skills: Onchocerciasis Control at the Village Level

Keeping accurate health records at the village level is a challenge since many rural dwellers have low or no literacy skills. The African Programme for Onchocerciasis Control (APOC) is distributing the drug ivermectin at the village level by villagers themselves, and requires an accounting of drugs dispensed and villagers treated. Recently, pictorial tally sheets were developed for Community Directed Distributors (CDDs) of ivermectin. At that same time a question arose concerning indigenous record keeping methods and whether such methods could also be adapted to ivermectin distribution. This study identified two indigenous methods, counting beans/pebbles and chalk/charcoal marks on walls and compared them with the pictorial tally sheets in three clusters of onchocerciasis-endemic villages in Kajola Local Government Area (LGA) of Oyo State, Nigeria. Field staff trained the CDDs using standard APOC procedures and after distribution, collected their treatment records. A household survey was then conducted for comparison with CDD records. The tally sheet users scored the lowest mean and median percentage point difference between reported and surveyed coverage (6.6 and 4.8) compared to chalk boards (19.0, 5.6) and pebbles (15.2, 9.2), but since the village was the unit of analysis, the differences observed were of only boarderline significance ( p = 0.08). Because the tally sheets proved to be both cheaper and easier to use, they are recommended for community ivermectin programs as well as other primary health care activities at the village level.

Onchocerciasis: the clinical and epidemiological burden of skin disease in Africa

An attempt was made to assess the true public-health importance of onchocercal skin disease throughout the African region and hence provide an objective basis for the rational planning of onchocerciasis control in the area. The seven collaborative centres that participated in the study (three in Nigeria and one each in Ghana, Cameroon, Tanzania and Uganda) were all in areas of rainforest or savannah-forest mosaic where onchocercal blindness is not common. A cross-sectional dermatological survey was undertaken at each site following a standard protocol. At each site, the aim was to examine at least 750 individuals aged 5 years and living in highly endemic communities and 220-250 individuals aged 5 years and living in a hypo-endemic (control) community. Overall, there were 5459 and 1451 subjects from hyper-and hypo-endemic communities, respectively. In the highly endemic communities, the prevalence of itching increased with age until 20 years and then plateaued, affecting 42% of the population aged 20 years. There was a strong correlation between the prevalence of itching and the level of endemicity (as measured by the prevalence of nodules; r=0.75; P<0.001). The results of a multivariate logistic regression analysis showed that, at the individual level, the presence of onchocercal reactive skin lesions (acute papular onchodermatitis, chronic papular onchodermatitis and/or lichenified onchodermatitis) was the most important risk factor for pruritus, with an odds ratio (OR) of 18.3 and 95% confidence interval (CI) of 15.19-22.04, followed by the presence of palpable onchocercal nodules (OR=4.63; CI=4.05-5.29). In contrast, non-onchocercal skin disease contributed very little to pruritus in the study communities (OR=1.29; CI=1.1-1.51). Onchocercal skin lesions affected 28% of the population in the endemic villages. The commonest type was chronic papular onchodermatitis (13%), followed by depigmentation (10%) and acute papular onchodermatitis (7%). The highest correlation with endemicity was seen for the prevalence of any onchocercal skin lesion and/or pruritus combined (r=0.8; P<0.001). Cutaneous onchocerciasis was found to be a common problem in many endemic areas in Africa which do not have high levels of onchocercal blindness. These findings, together with recent observations that onchocercal skin disease can have major, adverse, psycho-social and socio-economic effects, justify the inclusion of regions with onchocercal skin disease in control programmes based on ivermectin distribution. On the basis of these findings, the World Health Organization launched a control programme for onchocerciasis, the African Programme for Onchocerciasis Control (APOC), that covers 17 endemic countries in Africa.

Factors associated with coverage in community-directed treatment with ivermectin for onchocerciasis control in Oyo State, Nigeria

Community-directed distribution with ivermectin (CDTI) has been adopted by the African Programme for Onchocerciasis Control (APOC) as its main strategy for achieving sustained high coverage in endemic communities. This article describes the coverage results achieved when CDTI was introduced in four local government areas of Oyo State, Nigeria. Using a household survey after the second distribution, researchers documented that 68.6% of the community overall received the drug, and as did 85.0% of those who were eligible (not pregnant, not sick and at least 5 years of age). Six factors were associated with having received ivermectin. Four were personal characteristics: being male, being at least 35 years of age, belonging to the Fulani ethnic minority, having taken the drug at a previous distribution. Two village characteristics were smaller size, as measured by number of houses, and use of the central place mode of distribution as opposed to house-to-house. In-depth interviews with village leaders and volunteer community-directed distributors (CDDs) and focus group discussions among villagers provided qualitative data to help interpret the findings. Women in many villages felt excluded from decision making. The concerns of migrant farm workers living in Yoruba farm settlements were not well understood by health staff or the majority population. The main factor associated with receiving the ivermectin was having received it before, and qualitative comments about side-effects and beliefs about orthodox drugs indicated that issues of personal preferences, not addressed in a household coverage survey, need to be explored further. The findings can provide guidance in re-orienting health workers to the importance of fostering participation and cohesion among all segments of the community, especially the inclusion of women and minority groups.

The effects of ivermectin on onchocercal skin disease and severe itching: results of a multicentre trial

OBJECTIVE

To determine the effects of ivermectin in annual, 3-monthly and 6-monthly doses on onchocercal skin p6isease (OSD) and severe itching.

METHOD

A multicentre, double-blind placebo controlled trial was conducted among 4072 residents of rural communities in Ghana, Nigeria and Uganda. Baseline clinical examination categorized reactive skin lesions as acute papular onchodermatitis, chronic papular onchodermatitis and lichenified onchodermatitis. Presence and severity of itching was determined by open-ended and probing questions. Clinical examination and interview took place at baseline and each of 5 subsequent 3-monthly follow-up visits.

RESULTS

While prevalence and severity of reactive lesions decreased for all 4 arms, those receiving ivermectin maintained a greater decrease in prevalence and severity over time. The difference between ivermectin and placebo groups was significant for prevalence at 9 months and for severity at 3 months. Differences between placebo and ivermectin groups were much more pronounced for itching. From 6 months onward, the prevalence of severe itching was reduced by 40-50% among those receiving ivermectin compared to the trend in the placebo group.

CONCLUSION

This is an important effect on disease burden as severe itching is for the affected people the most troubling complication of onchocerciasis. The difference among regimens was not significant, and the recommended regimen of annual treatment for the control of ocular onchocerciasis appears also the most appropriate for onchocerciasis control in areas where the skin manifestations predominate. The final determination of the effect on skin lesions requires a longer period of study.

Stigma associated with onchocercal skin disease among those affected near the Ofiki and Oyan Rivers in western Nigeria

Skin diseases have been a major source of social stigma, whether they be infectious or not. The potential stigamtizing effect of skin disease associated with onchocerciasis is currently receiving attention because half of the 17 million victims of onchocerciasis in Africa live where the non-blinding form of the disease is prevalent. Some reports are available that onchocercal skin disease (OSD) is associated with social stigma including problems in finding a marriage partner. Previous studies have also implied positive effects of ivermectin treatment on OSD. Therefore a multi-country trial of ivermectin is underway to test the hypothesis that ivermectin treatment might affect perceptions of stigma associated with OSD. This paper presents the baseline stigma findings from the study site located in southwestern Nigeria. A total of 1032 persons living in villages near the Ofiki and Oyan Rivers were screened and interviewed and 500 (48%) were found to have an onchocercal skin lesion. A 13-item, 39-point stigma scale was used in interviews with affected persons. A mean score of 16.8 was obtained. No personal characteristics or disease factors were found to be associated with stigma score. The highest ranking items focused on issues of self-esteem such as feeling embarrassed, feelings of being pitied, thinking less of oneself, feeling that scratching annoys others, feeling that others thought less of the person and feeling that others had avoided the person. During the interviews it was discovered that only about half of those clinically diagnosed as having OSD labeled their own condition as onchocerciasis. Those who said their lesion was OSD had a lower stigma score than those who did not, conforming with previous studies wherein affected persons perceived less stigma from OSD than those without the disease. A broader community perspective on OSD was obtained through 50 interviews using paired comparisons of five skin-related local illnesses. Onchocerciasis placed midway in aversive responses between the higher end represented by leprosy and chicken pox and lower scoring papular rashes known locally as eela and ring worm. In-depth village based interviews yielded several case studies of how onchocerciasis had a negative social impact on its victims. While study on the cultural perceptions of OSD is recommended, the results indicate that with a fairly high prevalence of OSD, the community level effects of social stigma should be regarded as serious.

Results of a large scale onchocercosis survey in Enugu State, Nigeria

The prevalence of onchocercosis was determined in three Local Government Areas (Ezeagu, Oji-River and Uzo-Uwani) in Enugu State, Eastern Nigeria between March 1989 and June 1990. Enugu State was shown to be mesoendemic for onchocercosis. A total of 7472 (26.9%) persons out of 27,831 examined were positive for skin microfilariae. There was no significant difference in infection rates between males (27.6%) and females (26.2%). Of the 118 villages surveyed only five had no inhabitant with skin microfilariae. There was a progressive increase of prevalence to the second decade of life, although 96.6% of cases with skin microfilariae had only a light infection. Onchocercomata prevalence was recorded as 27.3% which tallies with the prevalence of skin microfilariae at 26.9% hence onchocercomata prevalence may be used as a yardstick for predicting skin microfilariae prevalence.

A clinical classification and grading system of the cutaneous changes in onchocerciasis

Although onchocerciasis is one of the most important diseases of the skin and eye in the tropical world, to date there has been no formal consensus regarding the description and terminology of skin lesions. Furthermore, the contribution of cutaneous pathology to the morbidity and socio-economic effects of the disease has been largely neglected. We present a clinical classification and grading system for recording the cutaneous changes of onchocerciasis, and propose that this system be used as a standard method of description to convey clinical information between workers in all endemic areas to assist local and comparative research.

Human onchocerciasis in the lower Jos Plateau, central Nigeria: the prevalence, geographical distribution and epidemiology in Akwanga and Lafia local government areas

An investigation of human infection with Onchocerca volvulus and the resulting clinical disease was carried out for the Nigerian National Onchocerciasis Control Programme between July and August 1989 [corrected]. The survey covered 10.6% of the rural population in 41 savanna villages of central Nigeria. Of the 8451 self-selected individuals examined, 900 (10.6%) had skin microfilariae (Mf). There were differences between villages in both endemicity and intensity of infection, but in general the number of both Mf carriers and cases of clinical onchocerciasis increased with age. The disease in the Mf carriers showed as blindness (0.8%), onchocercal nodules (0.6%), leopard skin (1.6%) and pruritus (2.8%). Of 35 persons with lymphatic complications, 19 had hanging groin, 10 had elephantiasis and six had hydrocoele. Onchocerciasis was mesoendemic in the rocky northern escarpments, and became hypoendemic and sporadic in the southern uplands of sedimentary geological origin.

Filariasis in the Igwun River Basin, Nigeria: an epidemiological and clinical study with a note on the vectors

In a cross-sectional, epidemiological and parasitological study of human filariasis, 845 individuals were examined in settlements along the Igwun Basin, Imo State, Nigeria. Four different filarial nematode species were identified. Two hundred and fifty-six (30.3%) of the individuals examined were positive for Onchocerca volvulus, 113 (13.4%) for Mansonella perstans, 76 (9.6%) for Wuchereria bancrofti and 77 (9.1%) for Loa loa. Microfilarial rates increased with age of individuals and showed a tendency towards higher prevalence rates in males than in females. The intensity of O. volvulus infection was high, with the highest microfilarial density of 44 mf mg-1 snip which occurred in the 40-49-year-old individuals. In W. bancrofti and L. loa infections, infections of over 1000 mf 20 ml-1 blood were recorded in 15.8% and 19.5% of individuals, respectively. Observed clinical signs were associated with inflammatory, lympho-obstructive and ocular manifestations. In M. perstans infections all clinical cases were inflammatory. In W. bancrofti, 44.4% of clinical cases were inflammatory, and lympho-obstructive manifestations consisted of 23.8% chyluria, 12.7% hydrocele and 19.1% elephantiasis. In L. loa infections all clinical cases were inflammatory with indications of Calabar swellings. In O. volvulus infections 23.5% of clinical cases were inflammatory, while 76.5% showed ocular manifestations. The absence of blindness despite high O. volvulus infection rates was remarkable. The presence of potential insect vectors and the occurrence of clinical signs are indications of active transmissions.

Onchocerciasis in Plateau State of Nigeria. II. The prevalence among residents around the Assob River area

A study of the prevalence of human onchocerciasis in eight villages around the Assob River in Jos Plateau, Nigeria, was undertaken between October 1983 and March 1985 using the skin-snip method. A total of 1673 individuals were examined. One hundred and eighty five (11.06%) had microfilariae of Onchocerca volvulus in their skin biopsies, and of these infected people, five (2.7%) were blind. The highest prevalence rate recorded was in Ngwan Madaki, where 51 (26.3%) of the 194 people examined were infected. The lowest percentage prevalence was recorded in Dogon Fili with four (1.95%) of the 205 people examined being positive. The proportion of infected people increased with age; and onchocercal lesions were significantly more common in older than in younger persons (P less than 0.05). There was no significant difference between infection rates in males and females (P greater than 0.05), although the overall percentage infection and the numbers of onchocercal lesions were higher in males than in females.

The status of human filariasis in relation to clinical signs in endemic areas of the Niger Delta

A study was carried out in selected parts of the Niger Delta Basin on human filariasis and its relationship to clinical signs. One hundred and seventy-six (13.0%) of 1351 individuals examined were infected with microfilaria. Forty-six percent of microfilaria positive cases had M. perstans; 25.6% had W. bancrofti, 19.3% had L. loa, and 9.0% had O. volvulus. The prevalence of filariasis increased with age. Microfilarial density was generally low, 28.4% of infected individuals had counts of 50-100 microfilaria per 20 mm3 blood, 12.5% had counts less than five microfilaria per 20 mm3 blood. Onchocerca microfilariae did not exceed five microfilaria per snip. Microfilarial density was high among individuals aged between 20 and 49 years, but declined with increasing age above 50 years. Acute clinical signs of febrile attack, sink eruptions, and chronic clinical signs of chyluria, hydrocoele, elephantiasis and ocular lesions were observed in 61.9% of infected individuals, 73.4% of clinical cases were febrile attack and skin eruptions, 5.5% were chyluria, 12.8% were elephantiasis of the leg and scrotum, 7.3% were hydrocoele and 0.9% were ocular lesions. Chronic clinical signs were more prevalent in individuals over 40 years of age.

Onchocerciasis in the Benue State of Nigeria. II. Prevalence of the disease among the Tivs living in the Kwande Local Government area

Between December 1979 and July 1980, a survey of the prevalence of onchocerciasis was carried out among the Tivs in the Kwande Local Government area of Benue State. Skin snips were taken from 372 people who were also inspected for the presence of skin nodules. Skin snips of 61, 72, and 71% of the people examined at Kuhe, Manor and Gube, respectively, showed Onchocerca volvulus microfilariae. The proportion of infected people increased with age, reaching a peak in the age group 31-40 years. Of the infected people 11.2% were blind; a higher proportion of infected males were blind compared with infected females. A greater proportion of infected males than females also had onchocercal nodules.

Babana Parasitic Diseases Project. I. The study area and a preliminary assessment of onchocercal endemicity based on the prevalence of "leopard skin"

A prevalence survey of "leopard skin" (LS) was carried out in 24 villages to assess the distribution of onchocerciasis in the Babana District of Nigeria. The findings suggested that onchocerciasis is highly endemic in this community. Of 1,310 adults examined for the presence of the characteristic onchocercal depigmentation, 26.4% were found affected. LS occurred more frequently among the cattle Fulani people than among other local ethnic groups (P less than 0.001) and was significantly more commonly associated with the left than with the right leg (P less than 0.001). A background of the study area is given.

Dermatological survey of onchocerciasis in Guatemala

A comprehensive survey of onchocerciasis was performed on 1259 inhabitants in San Vicente Pacaya and the surrounding area. The total number of inhabitants examined was 1259, 763 males and 496 females. An examination of microfilarial density was carried out by the skin snip method. There were 610 microfilarial positives (50.4%) out of 1211 persons, 448 males (60.9%), and 162 females (34.1%). Nodules were examined by palpation, and there were 404 (32.8%) positives for nodule out of 1232 persons, 299 males (40.3%), and 105 females (21.4%). Eczematous dermatitis was seen in 149 persons, the generalized type in 13, and other types in 136. Depigmentation on the lower extremities was seen in 290 persons, the severity was graded from 0 to 4, and grade 1 depigmentation was seen in 91; grade 2, in 143; grade 3, in 52 and grade 4 in 4 persons out of 1159 individuals examined. The positives for lymphadenopathy (above grade 2) were 464 (41.2%) out of 1127 individuals. Itching was seen in 129 (18.3%) of 705 individuals examined by the inquiry card method. The correlation between skin changes and onchocerciasis was also analyzed. Those individuals who were microfilarial positive in the skin snip and eyes, and who had palpable nodules were defined as being onchocerciasis patients. There was a high frequency of eczematous dermatitis, depigmentation on the lower extremities and lymphadenopathy in the onchocerciasis infected group, compared with the non-infected group, but there was no difference in the rate of itching between them. Hanging groin, elephantiasis and "erisipela de la costa" were not seen in this endemic area, and the degree of skin changes was slight, compared with that reported in Africa thus far.