Epidemiological studies of Mansonella ozzardi (Nematoda, Onchocercidae) in indigenous communities of Pauini municipality, Amazonas, Brazil

Abstract

The Mansonella ozzardi has a widespread distribution among the indigenous and riverine communities of Amazonas, Brazil. We estimated the prevalence of Mansonella ozzardi in indigenous communities of the Pauini municipality, Amazonas state, Brazil and the rate of parasitic infection in vectors. We collected thick blood smears from individuals from six Apurinã indigenous communities along the Purus River and its tributaries. Collections of simuliids were made and dissected, and the larval instars of M. ozzardi identified. The overall prevalence of M. ozzardi was 28.40%, with the highest incidence among males and agricultural workers. Among age groups, children 2-9 years of age had the lowest incidence, while individuals older than 58 exhibited the highest rates of infection. We found infected simuliids in three communities, with Parasitic Infection Rates (PIR) of 0.34-6.58%. The prevalence of M. ozzardi among the Apurinã people is high, possibly related to the diary activities of the riparian people, where a high abundance of the vectors exists. KEY WORDSMansonella ozzardi, Mansonelliasis, Simuliidae, Amazonas, Brazil. Estudos Epidemiológicos da

Mansonella ozzardi in Brazil: prevalence of infection in riverine communities in the Purus region, in the state of Amazonas

“…The prevalence in the Pauini population was higher than had been previously reported for the following municipalities of AM: Fonte Boa (17.8%), São Paulo de Olivença (12.6%), Uapés (10.5%), Coari (10%) and Codajas (23.9%) (Lacerda & Rachou 1956), Lábrea (4.4% and 5.9%) (Shelley 1975, Tavares 1981 and Coari (18.9%) (Cohen et al 2008). However, the prevalence was lower than that reported in the high Solimões (45.7%) and Pauini (28.4%) indigenous communities (Moraes et al 1978, Medeiros et al 2007). Indeed, a high prevalence has been found in some areas of Venezuela such as the state of Bolivar (36.4%) and in the Amazon Federal Territory (30%) (Medrano et al 1980, Formica & Botto 1990.…”

“…Previous studies carried out in different regions also found higher prevalence in males in Brazil (Shelley 1975, Moraes et al 1978, Lawrence et al 1980, Medeiros et al 2007, Mexico (Biagi 1956), Colombia (Lightner et al 1980, Kozek et al 1982, 1983 and Trinidad (Nathan et al 1979). This difference between the sexes may be a by-product of different occupations of males and females.…”

“…Additionally, the larval stages of M. ozzardi were also submitted to a new identification protocol using the polymerase chain reaction (Medeiros et al, unpublished observations). We calculated the PIR following Medeiros et al (2007). Infectivity Rate (IR) was calculated as the number of females infected with stage L3 M. ozzardi divided by the number of females dissected, multiplied by 100.…”

“…Due to the absence of data and the importance of M. ozzardi for Amazonian populations, studies are still necessary to understand the geographical distribution of the cases, as well as the individual and cultural characteristics of the population in endemic areas that make them prone to infection. Indeed, eye lesions possibly associated with M. ozzardi have already been reported in the municipality of Pauini (Branco et al 1998) and high prevalence rates were found in indigenous communities (Medeiros et al 2007). Thus, our goal was to obtain data on human infection by M. ozzardi through comparison of prevalence rates between genders, as well as to examine the relationships between M. ozzardi infection and age and professional occupation.…”

“…Recently, some studies have shown that this filaria is still found with high prevalence (Medeiros et al 2007(Medeiros et al , 2008 and that simuliids are incriminated in the parasite's transmission in Brazil (Cerqueira 1959, Shelley & Shelley 1976, Shelley et al 1980). Due to the absence of data and the importance of M. ozzardi for Amazonian populations, studies are still necessary to understand the geographical distribution of the cases, as well as the individual and cultural characteristics of the population in endemic areas that make them prone to infection.…”