Screening for high prevalence areas of onchocerciasis - a feasibility study on the application of the indirect questionnaire approach in Kafa; South Western Ethiopia

"A cross-sectional study was undertaken to test the validity and operational feasibilty of the so-called ""indirect questionnaire approach"" for the screening of communities for Onchocerciasis in Kafa; south west Ethiopia. Pretested questionnaire was distributed via the Awraja (district) education office to six junior high schools. Students were interviewed and their perceived morbidity; as reflected by the occurrence of selected features of Onchocerciasis; was recorded by their teachers. Subsequently a medical team has visited the same schools and undertook clinical and parasitological test to validate the first estimates. Using the Spearman's rank correlation; the positive response rate of students was found to be negatively correlated to the parasitological estimates of Onchocercal infection; probably due to the immune tolerance and adaptation to the features among the high prevalence groups; and poor perception of the problem in general. The indirect questionnaire approach using the educational sector is considered to be operationally feasible and 7.5 times less costly than the biomedical approach; but not advantages speed wise. Further study is recommended to assess the applicability of the method in different demographic and socioeconomic situations."

L'Onchocercose en milieu urbain : Cas du foyer de Brazzaville

Les auteurs rapportent les resultats cliniques; parasitologiques d'une enquete sur l'onchocercose realisee a Brazzaville au (Congo) en Mai 1992 par sondage en grappe selon la methode Henderson sur 1189 personnes ages de 5 ans et plus. Les indices recherches montrent que le taux de prevalence est de 40 pour cent; l'indice kystique a 2;4 pour cent. Un seul cas de cecite et tous facteurs etiologiques confondus a ete observe

Prevalence of Onchocerca Volvulus in Southern Sudan

Onchocerciasis is endemic in southern Sudan. The prevalence in human population may range from 10to 40. In the Eastern Equatorial Region of Southern Sudan; more cases are found in Nimule on the Sudan-Uganda border than in rural highlands of Labone and Chukudum basins. Onchocerciasis was highest in males (with a prevalence of 70.2based on data from hospital records)) than in females; with prevalence of 19. Overall; prevalence of onchocerciasis in children was 10.8.Considering cost-effectiveness; public health priorities and the security situation in this area; we recommend active search on onchocerciasis cases in the community and treatment

Etude epidemiologique de l'onchocercose dans la vallee de la Bini (Adamaoua) Cameroun : prevalence de l'infestation et charge parasitaire

L'Enquete epidemiologique effectuee dans la vallee de la Bini montre que l'onchocercose touche l'ensemble de la population urbaine. Les resultats obtenus dans les villages sont sensiblement identiques. On note en effet que la prevalence parasitaire est de 57;3pour les hommes et de 50;3pour les femmes. Cette difference entre les sexes est encore accentuee par le calcul du nombre moyen de microfilaires par biopsie entamee. Celui-ci est de 55 pour les hommes et de 22 pour les femmes

Etude epidemiologique de l'onchocercose dans la Vallee de la Bini (Adamaoua); Cameroun: pouvoir pathogene de la souche locale d'o. volvulus: atteintes oculaires et cutanees

A N'dena; dans la Vallee de la Bini (Ademaoua) ou la prevalence de l'onchocercose est de 51;4 pour cent d'apres la microfilarodermie; l'importance des atteintes cutanees et oculaires est mesuree. La depigmentation et l'atrophie cutanees s'observent chez 33;1 pour cent des habitants. Et 20;3 pour cent d'entre eux sont porteurs de kystes onchocerquiens. Des microfilaires sont vues dans le segment anterieur de l'oeil chez 23;3 pour cent des sujets et dans la chambre posterieure chez 9;8 pour cent. L'etude du pouvoir pathogene de la souche forestiere locale d'o. volvulus isolee met en evidence un contraste entre; d'une part; une infestation onchocerquienne massive et; d'autre part; la faible repercussion de cette pathologie sur la sante des populations

Etude epidemiologique des filarioses (onchocercose; loase; mansonellose); dans la vallee de la Kadei (Cameroun)

L'etude des filarioses est realisee dans trois villages proche du site prevu pour la construction d'un barrage sur la riviere Kadei (Cameroun oriental). La presence des microfilaires d'onchocerca volvulus est determinee par l'examen des biopsies cutanees. La prevalence parasitologique (37;9 pour cent) et les caracteristiques lesionnelles observees indiquent que l'onchocercose sevit dans la region au niveau de mesoendemie et se presente un facies de foret. Compte tenu de l'ecologie des vecteurs; cette etude d'impact montre que le barrage prevu ne devrait pas modifier d'une facon notable l'ecologie regionale et la transmission des filarioses dans la region

Premiere description de foyers d'onchocercose humaine au Gabon

Des foyers d'onchocercose a Onchocerca volvulus sont decrits pour la premiere fois au Gabon. Au cours des memes enquetes on note de fortes prevalences de porteurs de M. streptocerca et la premiere description chez l'homme de M. Rodhaini. 4922 sujets au cours de 10 enquetes portant sur l'ensemble du territoire gabonais ont subi une biopsie cutanee exsangue; un prelevement sanguin; un examen clinique. La prevalence globale des porteurs de O. volvulus est de 19;4 pour cent. Les regions les plus touchees sont : Makokou; Lebamba; Fougamou; Lastourville. Les hommes sont plus atteints que les femmes. L'infestation debute tot : 1;9 pour cent des enfants de 0-4 ans sont porteurs de microfilaires. La charge microfilarienne moyenne est de 30;7 microfilaires d'O. volvulus par biopsie. Les manifestations cliniques sont pauvres comparees a l'Afrique de l'Ouest : 36;3 pour cent des onchocerquiens sont porteurs de nodules. Les etudes des lesions oculaires n'ont porte que sur le segment anterieur de l'oeil; le pour centage de keratites ponctuees est moins important qu'en Afrique Sahelien

Prevalence of onchocerca volvolus [sic] in Mulago

Prevalence of onchocerca volvulus infection among patients attending skin clinic during the period of 3 years (1989-1991) at Mulago was determined. Out of the total 170 study group; 3 had positive skin snip tests for onchocerca volvulus. Most of the positives came from the known similium infested areas

Onchocerciasis distribution and severity in five West African countries

The Onchocerciasis Control Programme in West Africa recently extended its operation to Guinea, Guinea-Bissau, the western part of Mali, Senegal and Sierra Leone. To estimate the number of people infected and blinded by the disease and to determine its distribution and severity in the extension area, 215 villages were selected, using a stratified random sampling procedure, and surveyed. All the relevant entomological information available at the time was used in the sampling procedure and in the selection of 92 non-representative villages that were surveyed to confirm the findings. In addition, the populations of 608 villages were examined to map out in detail the distribution of onchocerciasis in the areas at a high risk of onchocercal blindness. The study estimated that 1,475,367 people were infected and 23,728 were blinded from onchocerciasis out of a rural population of 4,464,183. The northern and western part of the study area and the lower Niger basin presented a low or no risk of onchocercal blindness. The upper Niger basin, the south-central part of Sierra Leone, and three small foci in the Gambia, Bakoye, and lower Niger river basins were areas with a high risk of onchocercal blindness. The other parts of the study area presented a medium risk of onchocercal blindness. By detecting the communities at risk of onchocercal disease this study permits the selection of populations for disease control based on mass distribution of ivermectin, a microfilaricide

The predicted and observed decline in onchocerciasis infection during 14 years of successful control of Simulium spp. in West Africa

In 55 villages from the well-protected central area of the Onchocerciasis Control Programme in West Africa (OCP), skin snip surveys have been carried out at regular intervals since the programme started, and the latest round of surveys was undertaken after 12-14 years of successful vector control. The observed trends in the prevalence and intensity of onchocerciasis infection in cohorts of adults were compared with the trends predicted using a host-parasite model. After 12-14 years of control the community microfilarial load (CMFL) was close to zero in all villages. During the last few years of control, the prevalence of infection declined at an accelerated rate, and this was predicted by the model. There was generally good agreement between observed and predicted trends. The predictions were based on an estimated average duration of infection of 10.4 years, which corresponds to a mean reproductive lifespan for Onchocerca volvulus of 9-9.5 years, and an upper limit of 15 years for 95% of the infections. Differences between the observed and predicted data included the trend in CMFL between the first and second surveys, which in 18 villages did not show the predicted decline. Furthermore, the observed final decline in prevalence was faster than predicted in the north-eastern part of the central OCP area. After 14 years of vector control, the level of onchocerciasis has fallen to such a low level that consideration is being given to ending larviciding