Community-directed treatment of onchocerciasis with ivermectin in Takum, Nigeria.

A study to identify factors within the community that can ensure sustainable community-directed treatment (ComDT) with ivermectin compared the effectiveness of programme-designed (PD) and community-designed (CD) strategies in 37 villages in the Takum area of Nigeria. In a subset of PD villages, designated PD1, communities were asked to use the village heads as community-directed distributors (CDD), and the other communities (PD2) were asked to select female distributors, and both were instructed to use the house-to-house method of distribution. Community-designed communities, on the other hand, were asked to design their own approach. All study communities received health education, treatment guidelines, and training enabling them to determine appropriate dosage. A total of 1744 people were interviewed about their experiences after two treatment cycles. Communities preferred honest, reliable community members as CDDs, but few women were selected. The results show striking similarity between PD and CD villages in many respects. In the PD1 villages, where the programme designated the village head as CDD, the mode of distribution was changed from house-to-house to central point, and distribution took place in the compound of the village head. In the PD2 villages, where the programme specified distributors should be women, the women who were selected were replaced by their male children. These changes to the original design were consistent with the local cultural norms and made the arrangement for distribution more acceptable to the people. Programme-designed villages that used the village head as distributors performed better than those that used women, and the coverage in the former group compares well with that of CD villages. Only five villages achieved coverage > 60%, but dosage was correct in most cases (87.4%). Drug shortage was the most frequent reason for non-treatment. Communities devised means for ensuring equity and fairness in sharing their limited supply and freely altered the original designs to fit local norms and values. These changes to the original design were consistent with local norms and were acceptable to the people. The success of this strategy should be tested in other parts of Nigeria. Long-term success of ComDT, however, requires a reliable drug supply and inputs from professionals in the health system for minimal supervision. The core issues that determine sustainability of ComDT appear to be not so much in the structure, but in the process by which they are introduced. Communities will only sustain a programme where the process of implementation fits well with local norms and where communities are free to alter PD procedures that are inconsistent with local customs.

Human onchocerciasis: current assessment of the disease burden in Nigeria by rapid epidemiological mapping.

Rapid epidemiological mapping of onchocerciasis (REMO) was carried out in Nigeria between 1994 and 1996, to provide accurate estimates of the populations living in high-risk areas for the disease and to identify the communities to be given priority treatment with Mectizan (ivermectin, MSD). The rapid epidemiological assessment (REA) teams which carried out the survey comprised epidemiologists, geographers, and entomologists. They used topographical maps, at a scale of 1:250,000, to select sample villages at 30-km intervals along selected river courses. Several non-governmental development organizations participated in the surveys, providing support to the teams. In each study community, 50 adult males who had lived in the area for at least 10 years were randomly selected and examined for the presence of palpable, onchocercal nodules. The REA results were cross-validated by an independent REMO expert and then presented, initially as percentage prevalences in pie-chart form, using a geographical information system. The number of Nigerians living in high-risk areas (demarcated by river systems with villages that had > or = 19% prevalence) and who therefore require urgent Mectizan treatment, was estimated as 13,809,313. The national REMO map produced is allowing the African Programme for Onchocerciasis Control's technical consultative committee to prioritize the approval of proposals submitted from Nigeria in a rational and effective manner.

Comparison of two sample survey methods for hyperendemic onchocerciasis and a new focus in Dakka, Nigeria.

Most researchers rely only on large samples for the assessment of onchocerciasis prevalence in communities where it is endemic. However, because of the large population that must be included in the sample and the cost of surveys, several alternative methods are being explored. One is the selection of a small "at risk" sample of 30 persons from each community to determine the level of onchocercal endemicity. In this study both the Small Sample Survey (SSS) and the Complete Enumeration Survey (CES) techniques were used to determine the prevalence and intensity of onchocerciasis infection in sixteen communities in Dakka district, Nigeria, using conventional epidemiological procedures. The SSS showed that 82.3% of 390 at risk persons were microfilarial positive with a mean microfilaria density (MFD) of 90.9 microfilaria per skinsnip (MF/SS) and six communities were classified as hyperendemic (prevalence beyond 59.9%). The CES of 1529 persons produced a count of 78.2% positivity and a MFD of 88.44 MF/SS. For each of the physical symptoms of the disease and the MFD, computed T-test values showed that the SSS gives an estimate that is impressively close to the CES in the estimation of the prevalence of onchocerciasis in a community despite its low cost.

Trichomoniasis amongst students of a higher institution in Nigeria.

A total of 2048 urine specimens were examined to assess the infection prevalence and epidemiological factors of T. vaginalis amongst students in a Nigerian higher institution. Five hundred and five students were infected (24.7%). This included 131 (15.6%) males and 374 (31.0%) females. More male than female students were found to be asymptomatic. Infection was significantly higher in females than males and in the second and third than the fourth and fifth decades of life (P < 0.05). Infection increases progressively with increase in the number of sexual partners. The use and neglect of condoms were also assessed. The pH range of the vagina of most infected females was between 5.8-8.2. Clinical symptoms noted among females were local tenderness, vulval pruritus and intermittent burning sensations in addition to profuse vaginal discharges. The public health implication of the findings and some epidemiological factors enhancing the disease transmission are presented.

Non-ocular clinical onchocerciasis in relation to skin microfilaria in the Taraba River Valley, Nigeria.

Examination of 2,876 persons in fourteen communities was carried out for clinical onchocerciasis on the Taraba river valley, Nigeria, where parasitological findings indicate unusually high endemicity. Forty-five percent of the population had at least one type of skin lesion or the other, the commonest of which was pruritus. Thirty-two percent had nodules. Some of the nodules were located in unusual sites such as the mammae, anus. Nodule carriage and nodule-load as well as lymphatic enlargement were higher than those recorded elsewhere in Nigeria and tended to increase with increase in age. When subjected to regression analysis, the relationship between skin lesion, nodule carrier rate, nodule load, scrotal enlargement and microfilaria rate (mf) on one hand and microfilaria density (mfd) on the other showed a near-perfect correlation. The findings of this study suggest that certain clinical manifestations of onchocerciasis may be a reliable and more rapid alternative to the parasitological approach in the assessment of the prevalence and severity of the disease in communities with similar socioecological characteristics.

The occurrence of loiasis, mansonellosis and wuchereriasis in the Jarawa River Valley, central Nigeria.

In a study to assess the status of filariasis in the Jarawa River Valley of the savanna area of Nigeria, 940 self-selected residents from 10 villages were examined between March 1984 and April 1987. Overall results showed 105 (11.2%) had microfilaraemia and/or clinical signs of filariasis. Sixty-four (6.8%) and 20 (2.1%) persons, respectively, were infected with Mansonella perstans and Loa loa microfilariae (mff). Four of the 28 villagers examined had Wuchereria bancrofti mff in their night blood samples whereas 17 (1.8%) of all residents surveyed had clinical filariasis mainly due to lympho-obstructive manifestations: hydrocele (n = 11, 64.7%); enlargement of the inguinal nodes (n = 8, 47.1%) and elephantiasis (n = 2, 11.8%).

Evaluation of skin biopsies from different body regions of onchocerciasis patients in Central Nigeria.

The diagnostic potential of skin snips from different body regions was evaluated in 97 onchocerciasis patients of Central Nigeria. Biopsies from the iliac crest had the greatest diagnostic potential followed by those of the calf and shoulder with 95% of Onchocerca volvulus carriers being diagnosed from these sites. However, 23.7% of microfilarial carriers in the skin of the outer canthus, shoulder, calf and ankle were negative in the iliac crest. The probability of diagnosing onchocerciasis in microfilarial positives from the 5 sites was, 0.76 for the iliac crest; 0.63 for the calf; 0.31 for the shoulder; 0.27 for the ankle; and 0.08 for the outer canthus. The concentrations of microfilariae in skin snips were significantly associated with the probability of a positive diagnosis especially with regard to those of the shoulder, iliac crest and calf.