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

Abstract

This study was undertaken to investigate the prevalence of Mansonella ozzardi infection and to estimate the parasitic infection rate (PIR) The filaria Mansonella ozzardi, one of the aetiological agents of mansonelliasis, is found on the American continent, as well as countries in the Caribbean. In South America, it has been reported in Panama, Colombia, Venezuela, Guyana, Suriname, Brazil, Argentina and Peru (Kozek et al. 1982). M. ozzardi is transmitted by Diptera insects of the families Ceratopogonidae in the Caribbean islands and Ceratopogonidae and Simuliidae in Central and South America (Shelley & Coscarón 2001).The pathogenicity of this filaria is not well defined. Several infected individuals show no symptoms; however, clinical manifestations that decrease the quality of life such as moderate fever, coldness in the legs, joint pains and headaches have been attributed to M. ozzardi infection (Batista et al. 1960b). Recently, the presence of ocular lesions has been reported as possibly associated with M. ozzardi infection (Branco et al. 1998, Cohen et al. 2008.The microfilaria M. ozzardi was detected in Brazil in the 1940s and 1950s (Deane 1949, Deane et al. 1954, Lacerda & Rachou 1956) and was described as a potentially extensive problem (Moraes 1958). 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. 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. We also sought to identify the simuliid species involved in the transmission of M. ozzardi and to estimate the Parasitic Infection Rate (PIR) of the vectors. MATERIALs AND METHODsStudy area and population -This study was performed in the Purus and Pauini riverine communities in the municipality of Pauini (07º421'S 67º01'W), Amazonas (AM) (Fig. 1). The municipality of Pauini is located in southwest AM, about 900 km from Manaus. It has 17,092 inhabitants, with 6,970 in the urban zone and 10,122 in rural areas (IBGE 2000). The region is covered by native primary forest and presents long flood areas, accessible only by plane or boat. The rainy season is usually from November-March, with average annual temperatures between 24-26ºC, and a relative humidity bet...

Improvement of a PCR test to diagnose infection by Mansonella ozzardi

“…This filariasis was first reported in Brazil in the City of Manaus in the State of Amazonas 2 and people infected by M. ozzardi were later identified along the Solimoes, Purus and Negro Rivers 3 . These findings reinforce many studies that have warned that M. ozzardi was widely distributed in the State of Amazonas 4 , Brazil; however studies concerning this filariasis remain scarce [5][6][7] .…”

Mansonella ozzardi (Nematoda: Onchocercidae) in the riverine population of the Tefé River, State of Amazonia, Brazil

“…In addition, our results are in agreement with those of Batista et al 5 , Shelley 6 , and Medeiros et al 7 , who found no statistically significant difference in the prevalence rates between sexes. However, other epidemiological studies have reported a higher disparity between the prevalence rates in males and females 4,8 .…”

Investigação da ocorrência da Mansonella ozzardi no Estado de Rondônia, Amazônia Ocidental

“…There is a question of whether the diagnosis method used in this study was not sensitive enough to detect low rates of microfilaremia. However, many studies carried out in the Amazon use the same method and show prevalence of up to 60% of microfilaremia [7][8][9] . Another hypothesis may be that there are not enough individuals infected with a high enough parasite load to disseminate this endemic disease in areas not affected by the infection.…”

“…Later, some researchers observed individuals infected with M. ozzardi alongside the Solimoes, Purus and Negro Rivers in the State of Amazonas [4][5][6] . Recent data have indicated that this parasite is still found with high prevalence rates in the Amazonian territory [7][8][9] .…”