Mansonella ozzardi in Amazonas, Brazil: prevalence and distribution in the municipality of Coari, in the middle Solimões River

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Revista da Sociedade Brasileira de Medicina ABSTRACT Introduction:This study assessed the prevalence of Mansonella ozzardi in riverine communities of the Tefé River, Amazonas, Brazil. Methods: The prevalence of M. ozzardi was estimated by microscopic examination of thick blood smears. Results: The M. ozzardi prevalence rate was 6.3% (19/300). Filarial infection was found in 8 of the 11 communities surveyed, with prevalence rates varying from 2.5% to 22.2%. Conclusions: Tefé is a region of oil and natural gas exploration, in which there is a high turnover of workers. Migration patterns may facilitate the dissemination of mansonelliasis to other regions.Keywords: Mansonella ozzardi. Tefé River. Amazonas.An epidemiological survey of mansonelliasis was conducted in Tefé, State of Amazonas, Brazil, in the 1950s and reported a prevalence rate between 2.5% and 18.7% for Mansonella ozzardi 1 . However, no other surveys have been conducted in this region, and current knowledge pertaining to the occurrence of mansonelliasis is based on records from the Foundation Surveillance Health (FVS) in Tefé obtained during a routine malaria survey (JF Medeiros: personal information). In Tefé, there is a significant population of migrant workers who are employed at companies that extract oil and natural gas. These companies employ many workers from regions without mansonelliasis, and this migration demonstrates the potential for the spread of mansonelliasis to non-endemic regions when these migrant workers return to their native communities. This study was the first survey of human filarial mansonelliasis in the Tefé River region of oil and gas production, and it was conducted to investigate the prevalence of M. ozzardi among the resident population of the Tefé River region.The present study was conducted among people living along the Tefé River in the municipality of Tefé (3°30'S 64°58'W), State of Amazonas, Brazil. The Tefé River, a tributary of the Solimões River, is an area rich in oil and gas, with continuous mineral extraction (Figure 1). The population density of the area is low, and the people live in small communities dispersed along the riverbanks and generally practice subsistence farming (fishing and agriculture).The work presented here was part of a pilot study to provide baseline data for the design of future, more detailed studies. Individuals present at the initiation of the study were informed of the purpose and scope of the study and were invited to participate. Informed verbal consent to participate in the study was obtained from adult participants and the parents of child participants during community meetings. According to the Foundation of Surveillance in Health in Tefé, the population along the Tefe River numbers approximately 850. A total of 300 individuals (~35% of the population) between the ages of 2 and 82 years were included in this study and examined by rapid epidemiological mapping for microfilariae of M. ozzardi in June 2012. This study received approval from the Ethical Committee of the Tropical Medic...

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confidence: 67%

“…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 .…”

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confidence: 76%

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

Medeiros

Costa

Lima

et al. 2014

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“…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] .…”

Section: Introductionmentioning

confidence: 99%

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

Basano

Camargo

Vera

et al. 2011

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Introduction: Mansonella ozzardi, a human filarial nematode transmitted by Diptera Simuliidae flies (black flies), is widely spread in the Amazon, while the occurrence of mansonelliasis in the State of Rondônia (Western Amazonia) has not been reported thus far. The existence of this parasitic disease in this state is investigated in this study. Methods: A total of 4,452 people who lived alongside the Madeira, Mamore, Guapore, Machado and Preto Rivers, in the State of Rondônia, were examined using the thick blood smear method. Alongside the Machado and Guapore rivers, 2,112 adult simuliid specimens were captured. Results: Infected people were not reported, although simuliids with vector potential such as Cerqueirellum pydanielli, C. argentiscutum and C. amazonicum were found. Conclusions: This study registered no infected people. This finding may be explained by the individuals' low level of microfilaremia that is below the limit of detection of the diagnostic method used in the study or insufficient migration of people infected with M. ozzardi from endemic areas, making it impossible to introduce the disease into Rondônia. Further studies using more sensitive diagnostic techniques could shed light on this question.Keywords: Mansonella ozzardi. Microfilariae. Simuliidae. State of Rondônia. RESUMOIntrodução: Mansonella ozzardi é uma filária humana que tem como vetor dípteros simulídeos e é amplamente distribuída na Amazônia. Não há informações sobre a ocorrência de casos de mansonelose no Estado de Rondônia, e neste trabalho procurou-se investigar a situação epidemiológica desta parasitose em áreas urbanas e ribeirinhas na Amazônia Ocidental. Métodos: Foram examinados 4.452 moradores às margens dos rios Madeira, Mamoré, Guaporé, Machado e Preto em Rondônia, através da técnica da gota espessa de sangue. Capturou-se às margens do rio Machado e Guaporé 2.112 simulídeos adultos das espécies Cerqueirellum pydanieli e Chirostilbia pertinax. Resultados: Não foram encontradas pessoas infectadas com M. ozzardi e foram encontradas diferentes espécies de simulídeos com potencial de transmissão da mansonelose. Conclusões: Não foram encontrados indivíduos infectados com M. ozzardi neste estudo. Este fato pode ser explicado pela existência de pacientes com baixas microfilaremias, associado à técnica diagnóstica de baixa sensibilidade utilizada no estudo. Pode-se ainda aventar a possibilidade de ter ocorrido migração insuficiente de pacientes infectados de áreas endêmicas, impossibilitando a implantação da endemia. Estudos posteriores com técnicas diagnósticas mais sensíveis podem ajudar a esclarecer esta questão. Palavras-chaves:Mansonella ozzardi. Microfilárias. Simuliidae. Rondônia.

“…Mansonella ozzardi is a widely distributed fi laria worm that parasitizes humans in Amazonas State, Brazil, with high prevalences detected in residents of some regions of the Solimões, Negro, and Purus Rivers (1) (2) (3) (4) (5) . Simuliidae (blackfl ies) are the only vector of M. ozzardi in Brazil (6) (7) .…”

mentioning

confidence: 99%

“…This is possibly one of the factors responsible for accumulation of parasites in individuals, maintaining several adult worms of different ages with continuous production of microfi lariae, infection, and transmission by insect vectors (3) (5) . There are no previous reports of residence duration and prevalence rates of mansonelliasis; however, this relationship possibly also occurs in other regions.…”

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confidence: 99%

Occurrence of Mansonella ozzardi diagnosed using a polycarbonate membrane in a riverside population of Lábrea in the Western Brazilian Amazon

Basano

Medeiros

Fontes

et al. 2016

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Introduction:Mansonella ozzardi is a widely distributed fi laria worm in the Amazon region. This study aimed to determine the prevalence of M. ozzardi infection in riverine communities of Lábrea municipality, Amazonas State, Brazil. Methods: A diagnostic blood fi ltration method in a polycarbonate membrane was used. Results: M. ozzardi was found in 50.3% of the sample, with the highest prevalence in farmers/fi shermen (69.4%; χ 2 = -19.14, p<0.001). The prevalence was higher in longerterm residents (≥11 years; 60.2%). Conclusions: M. ozzardi infection rates are high near the Purus River, much greater than those previously reported based on diagnosis using thick blood smears.Keywords: Mansonelliasis. Mansonella ozzardi. Brazilian Amazon.Mansonella ozzardi is a widely distributed fi laria worm that parasitizes humans in Amazonas State, Brazil, with high prevalences detected in residents of some regions of the Solimões, Negro, and Purus Rivers (1) (2) (3) (4) (5) . Simuliidae (blackfl ies) are the only vector of M. ozzardi in Brazil (6) (7) .An endemic region for M. ozzardi in Brazil is in the municipality of Lábrea, in the Purus River region, Amazonas, where it has been detected since the fi rst survey in the 1950s (1) . Subsequent studies conducted in the 1970s and 1980s confi rmed the wide distribution of M. ozzardi in this region (8) (9) . More recently, the prevalence of the infection had reportedly increased in riverine communities located near the Purus and Ituxi Rivers (2) (3) (4) .In the Purus River region, only Adami et al. (10) utilized the concentration method by Knott to diagnose mansonelliasis. Therefore, the present study aimed to determine the prevalence of M. ozzardi infection in riverine communities of the Lábrea municipality using a diagnostic blood fi ltration method in a polycarbonate membrane, which is more sensitive than thick blood smears (11) .This study was conducted in the riverside communities of the Purus River (Cassianã, Bacural, Jucuri, Buraco, Santa Rosa, Jurucuá and Samaúma), located approximately 200km from the municipality of Lábrea communities (S: 07º15' 34" and W: 64º47'59"), State of Amazonas, Brazil (Figure 1). The sample consisted of volunteer men, women, and children aged 5-60 years selected using convenience sampling. Data and blood samples were collected after signing the free and informed consent form by the individual or the legal guardian. Of the estimated 350 inhabitants in the included communities, 171 (48.6%) inhabitants were present at the time of the study and agreed to participate.To estimate the prevalence of Mansonella ozzardi, blood was filtrated in a polycarbonate membrane (12) . First, 1mL venous blood was collected from each individual, diluted in 10mL 0.9% saline, and fi ltered in a polycarbonate membrane (Nucleopore Corporation, Pleasanton, CA, USA) with a 3µm pore diameter. Then, the membranes were removed from the fi lters and mounted on microscope slides, fi xed in methanol, stained with a Panoptic kit ® , and examined under an optical micros...