Spatial and Genetic Epidemiology of Hookworm in a Rural Community in Uganda

There are remarkably few contemporary, population-based studies of intestinal nematode infection for sub-Saharan Africa. This paper presents a comprehensive epidemiological analysis of hookworm infection intensity in a rural Ugandan community. Demographic, kinship, socioeconomic and environmental data were collected for 1,803 individuals aged six months to 85 years in 341 households in a cross-sectional community survey. Hookworm infection was assessed by faecal egg count. Spatial variation in the intensity of infection was assessed using a Bayesian negative binomial spatial regression model and the proportion of variation explained by host additive genetics (heritability) and common domestic environment was estimated using genetic variance component analysis. Overall, the prevalence of hookworm was 39.3%, with the majority of infections (87.7%) of light intensity (≤1000 eggs per gram faeces). Intensity was higher among older individuals and was associated with treatment history with anthelmintics, walking barefoot outside the home, living in a household with a mud floor and education level of the household head. Infection intensity also exhibited significant household and spatial clustering: the range of spatial correlation was estimated to be 82 m and was reduced by a half over a distance of 19 m. Heritability of hookworm egg count was 11.2%, whilst the percentage of variance explained by unidentified domestic effects was 17.8%. In conclusion, we suggest that host genetic relatedness is not a major determinant of infection intensity in this community, with exposure-related factors playing a greater role

Sporadic onchocerciasis in the lower Imo River basin, Nigeria

Onchocerca volvulus is present in the Lower Imo River Basin with a mf prevalence of 3.5%,. Microfilaraemia was higher among older than younger individuals and there was no significant difference in prevalence between sexes. Microfilarial intensities varied significantly between sexes and also between age groups. On the overall, prevalence of clinical onchocerciasis was higher than prevalence of microfilaraemia. The commonest clinical manifestation related to O. Volvulus was permanent itching, and visual acuity problem. A total of 42 (48.8%) of the individuals with permanent itching were positive for O. volvulus microfilaraemia. The difference mf prevalence between the two categories was not statistically significant (&#967;2-test; p 0.05). The O. volvulus microfilaraemia was higher among those who presented visual acuity problems with an mf prevalence of 11.9% and an mf GMI of 27 mf/skin snip. For those who did not present with visual acuity problems, 2.5% were positive for O. volvulus microfilaraemia, with an mf GMI of 19 mf/skin snip. The difference in mf prevalence was statistically significant (&#947 2-test; p < 0.01); and the difference in mf GMI was also statistically significant (t-test;

Bancroftian filariasis in the lower Imo River Basin, Nigeria

Wuchereria bancrofti is present in the Lower Imo River Basin with a prevalence of 6.7%. Microfilaraemia was higher among older than younger individuals and there was no significant difference in prevalence between sexes. Microfilarial intensities varied significantly between sexes and also between age groups. On the overall, prevalence of clinical filariasis was higher than prevalence of microfilaraemia. Clinical manifestations related to W. bancrofti were hydrocele, limb and scrotal elephantiasis in that order of importance. Limb elephantiasis was higher among females than among males. Chyluria was not found in the Lower Imo River Basin study population. AJAZEB Vol. 6 2004: pp. 61-6

High malnutrition rate in Venezuelan Yanomami compared to Warao Amerindians and Creoles: significant associations with intestinal parasites and anemia

Contains fulltext : 125614.pdf (publisher's version ) (Open Access)BACKGROUND: Children in rural areas experience the interrelated problems of poor growth, anemia and parasitic infections. We investigated the prevalence of and associations between intestinal helminth and protozoan infections, malnutrition and anemia in school-age Venezuelan children. METHODS: This cross-sectional study was conducted in 390 children aged 4-16 years from three rural areas of Venezuela: the Amazon Region, Orinoco Delta and Carabobo State. Stool samples were collected for direct parasitic examinations. Anthropometric indicators of chronic (height-for-age Z score) and acute (weight-for-height and Body Mass Index (BMI)-for-age Z score in respectively children under 5 years of age and children aged 5 years and above) malnutrition were calculated. Multivariate linear and logistic regression models were built to determine factors associated with nutritional status and polyparasitism. RESULTS: Hookworm and Strongyloides stercoralis prevalences were highest in children from the Amazon rainforest (respectively 72% and 18%) while children from the Orinoco Delta and Carabobo State showed higher rates of Ascaris lumbricoides (respectively 28% and 37%) and Trichuris trichiura (40% in both regions). The prevalence of Giardia lamblia infection was not significantly different between regions (average: 18%). Anemia prevalence was highest in the Amazon Region (24%). Hemoglobin levels were significantly decreased in children with a hookworm infection. Malnutrition was present in respectively 84%, 30% and 13% of children from the Amazon Region, Orinoco Delta and Carabobo State. In multivariate analysis including all regions, G. lamblia and helminth infections were significantly and negatively associated with respectively height-for-age and weight-for-height/BMI-for-age Z scores. Furthermore, hemoglobin levels were positively associated with the height-for-age Z score (0.11, 95% CI 0.02 - 0.20). CONCLUSIONS: In rural populations in Venezuela helminthiasis and giardiasis were associated with acute and chronic nutritional status respectively. These data highlight the need for an integrated approach to control transmission of parasites and improve the health status of rural Venezuelan children

Estudo comparativo de áreas endêmicas de filariose bancroftiana na região metropolitana do Recife, Brasil Comparative studies on endemic areas of bancroftian filariasis in Greater Recife, Brazil

Para se realizar o estudo comparativo da filariose bancroftiana na área metropolitana do Recife, foram selecionados dois bairros da cidade do Recife (Santo Amaro e Campo Grande) e dois bairros da cidade de Olinda (Sapucaia e Salgadinho), segundo critério apoiado na semelhança das características sócio-econômicas e demográficas e dos níveis endêmicos de filariose. As áreas foram divididas em conglomerados, com 25 casas em média. A amostra populacional foi estratificada por sexo e faixa etária de 0-4, 5-9, 10-14, 15-19, 20-29, 30-39, 40-49, 50-59 e igual ou superior a 60 anos. Os dados parasitológicos foram obtidos por meio da gota espessa mensurada (60µl de sangue), coletada entre as 20 e 24 horas, processada e corada pelo método de Carrazi. Os dados obtidos foram descritos em tabelas, e a densidade parasitária e freqüência microfilarêmica analisadas através de gráficos com expressão logarítima. De maneira global, Recife apresentou prevalência de 13,5%, e Olinda, 12,3%. Quando comparamos a densidade parasitária, Olinda apresentou valor médio de 70 microfilárias por 60µl de sangue, e Recife, 41. Em relação aos índices microfilarêmicos, o maior ocorreu na faixa etária de 20-29 anos. Em Olinda, por outro lado, situou se entre 30-39 anos e em indivíduos do sexo masculino. Os autores concluem que a endemia apresenta níveis endêmicos do passado, e os dados descritos alertam para uma reavaliação das campanhas de controle realizadas pela Fundação Nacional de Saúde (FNS), já que a endemia atinge dimensões ainda não mensuradas.<br>Two districts in Recife (Santo Amaro and Campo Grande) and two districts in Olinda (Sapucaia and Salgadinho), were selected for a comparative study of bancroftian filariasis in Greater Recife. Selection parameters included similar socio-economic, demographic, and endemic levels of lymphatic filariasis. In the districts studied, streets were chosen randomly. These clusters consisted of 110 people each. A population sample was stratified by sex and age: 0-4, 5-9, 10-14, 15-19, 20-29, 30-39, 40-49, 50-59 and 60 years old and over. The parasitological data were obtained by measuring thick blood smears (60µl), collected from 8:00 to 12:00 PM and processed and stained with hematoxylin. The data were described in tables, and logarithimic expression graphics were used to analyze parasitic densities. In general, Recife showed a prevalence of 13.5%, and Olinda 12.3%. Mean parasitic densities were 41 and 70 microfilariae/60µl (mf/60µl), respectively. Higher microfilaremic rates were observed in Recife for the 20-29-year age bracket and in Olinda in the 30-39-year bracket. The authors concluded that the disease has returned to former endemic levels, and the data described call for a reevaluation of control campaigns carried out by the Brazilian National Health Foundation, since the endemic has already reached serious proportions