New records of Mansonella ozzardi: a parasite that is spreading from the state of Amazonas to previously uninfected areas of the state of Acre in the Purus River region

Mansonella ozzardi infections are common in the riverside communities along the Solimões, Negro and Purus Rivers in the state of Amazonas (AM). However, little is known about the presence of this parasite in communities located in regions bordering AM and the state of Acre. The prevalence rate of M. ozzardi infections was determined in blood samples from volunteers according to the Knott method. A total of 355 volunteers from six riverine communities were enrolled in the study and 65 (18.3%) were found to be infected with M. ozzardi. As expected, most of the infections (25%) occurred in individuals involved in agriculture, cattle rearing and fishing and an age/sex group analysis revealed that the prevalence increased beginning in the 40-50-years-of-age group and reached 33% in both sexes in individuals over 50 years of age. Based on the described symptomatology, articular pain and headache were found to be significantly higher among infected individuals (56 and 65% prevalence, respectively, p < 0.05). Sera from volunteers were subjected to ELISA using a cocktail of recombinant proteins from Onchocerca volvulus to evaluate the specificity of the test in an endemic M. ozzardi region. No cross-reactions between M. ozzardi-infected individuals and recombinant O. volvulus proteins were detected, thus providing information on the secure use of this particular cocktail in areas where these parasites are sympatric.

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

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. .

Aporte de la técnica de PCR en el diagnóstico de Mansonella ozzardi en zonas endémicas de la Argentina / Contribution of the PCR assay to the diagnosis of Mansonella ozzardi in endemic areas of Argentina

Mansonella ozzardi es un nematode parásito tisular, agente etiológico de mansonellosis en casi la totalidad de los países latinoamericanos. En Argentina la mansonellosis ha sido descrita a lo largo de la región de las yungas. Su diagnóstico microscópico puede dar resultados falsos negativos en microfilaremias bajas. El objetivo del presente estudio fue optimizar su diagnóstico molecular y comparar los resultados con los obtenidos mediante las pruebas microscópicas de Knott, de gota gruesa y de extendido hemático fino, en 92 muestras de sangre de pacientes de zona endémica. La técnica de PCR seguida de la secuenciación del producto amplificado presentó una sensibilidad del 100 % frente al método de Knott, considerado como referencia, e incluso permitió identificar 7 casos más de la parasitosis.

Mansonella ozzardi is a tissue-dwelling parasitic nematode, the causative agent of mansonelliasis in almost all Latin American countries. It has been described along the Argentine Yungas region. The microscopic diagnosis can yield false-negative test results at low microfilaremia levels. The aim of this study was to optimize the molecular diagnostic technique and compare it with the Knott's method and standard blood smear procedures (thin blood films and thick smears) in 92 blood samples of individuals from an endemic area. The PCR technique followed by the sequencing of the amplified product yielded 100 % sensitivity compared to the Knott's test, which is considered a reference method. Seven more cases of this parasitosis could only be identified with the molecular technique.

Investigation of the occurrence of Mansonella ozzardi in the State of Rondônia, Western Amazonia, Brazil / Investigação da ocorrência da Mansonella ozzardi no Estado de Rondônia, Amazônia Ocidental

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.

INTRODUÇÃO: 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.

Prevalence of Mansonella ozzardi among riverine communities in the municipality of Lábrea, State of Amazonas, Brazil / Prevalências de Mansonella ozzardi entre comunidades ribeirinhas do município de Lábrea, Estado do Amazonas

INTRODUCTION: Estimate the prevalence of Mansonella ozzardi infection and calculate the parasitic infection rate (PIR) in simuliid black flies in the municipality of Lábrea, State of Amazonas, Brazil. METHODS: Prevalence was measured using the thick blood smear method collected from the fingers and was related to age, sex and occupation. Simuliidae were collected with a suction apparatus, then stained with hematoxylin and dissected to verify the PIR. RESULTS: The average prevalence rate of M. ozzardi among the 694 individuals examined was 20.7 percent. Infection was higher in men (27.6 percent) than in women (14.3 percent) (p < 0.001) and occurred in most age groups, with the highest prevalence in the following age groups: 38-47 (40 percent), 48-57 (53.1 percent) and >58 (60.5 percent). The highest prevalence rates were observed in the retired (64 percent), followed by farm workers (47.1 percent). Infection by M. ozzardi was only identified in Cerqueirellum amazonicum (Simuliidae) with a PIR of 0.6 percent. CONCLUSIONS: This study showed a high prevalence of M. ozzardi in the riverine communities of Lábrea due to the lack of policies regarding the treatment of microfilaremic individuals in the region and an abundance of competent vectors for M. ozzardi.

INTRODUÇÃO: Estimar as prevalências de Mansonella ozzardi, e calcular a taxa de infecção parasitária nos simulídeos no município de Lábrea, Estado do Amazonas. MÉTODOS: As prevalências foram obtidas através do método de gota espessa a partir do sangue coletado da polpa digital e foram relacionadas com a idade, sexo e ocupação. Os simulídeos foram coletados com capturador de sucção, posteriormente foram corados com hematoxilina e dissecados para se obter a taxa de infecção parasitária. RESULTADOS: A prevalência de M. ozzardi entre as 694 pessoas examinadas foi de 20,7 por cento. A infecção foi maior nos homens (27,6 por cento) do que nas mulheres (14,3 por cento) (p < 0,001) e ocorreu na maioria das faixas etárias com maiores prevalências nos indivíduos entre 38-47 (40 por cento), 48-57 (53,1 por cento) e >58 (60,5 por cento) anos. As maiores prevalências foram observadas nos aposentados (64 por cento) e agricultores (47,1 por cento). Somente Cerqueirellum amazonicum (Simuliidae) foi encontrado infectado com M. ozzardi com uma taxa de infecção parasitária de 0,6 por cento. CONCLUSÕES: Este trabalho mostra elevadas prevalências de M. ozzardi nas comunidades ribeirinhas de Lábrea devido à ausência de políticas de tratamento dos microfilarêmicos na região e a abundância de vetores competentes.

Importância do método de gota espessa de sangue no diagnóstico de filárias simpátricas no Amazonas, Brasil / The importance of thick blood film method for sympatric filarial diagnosis in Amazon basin

Esse trabalho relata os métodos de diagnósticos para filárias humanas no sangue, referindo-se a importância do método de gota espessa em relação aos métodos de filtração em membrana de policarbonato e Knott na diferenciação das espécies de microfilárias, principalmente em áreas de ocorrência de mais de uma espécie, como em regiões do Amazonas. Lâminas com microfilárias de Mansonella ozzardi foram montadas e fotografadas pelos diferentes métodos de diagnósticos. O método da gota espessa de sangue é o mais confiável, pois permite visualizar com nitidez o espaço cefálico e caudal, disposição dos núcleos caudais e formato da cauda, que são características morfológicas que diferenciam as espécies de microfilárias sanguíneas que ocorrem no Amazonas.

In this work, the visual diagnostic methods for human filarias in the blood are evaluated. The thick blood film method is more faithful to identify the microfilariae species if compared to policarbonate membrane filtration and Knott methods, especially in areas where more than one species occur, as in Amazon basin. Slides with Mansonella ozzardi microfilariae were mounted and photographed by different diagnosis methods. The thick blood film method is much easier to see the diagnostic morphological characters as cephalic and caudal space, pattern of nucleation of the tail and tail shape that can separate the blood Amazonian microfilariae species.

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

This study investigated some epidemiological aspects of the Mansonella ozzardi in municipality of Coari, Amazonas. Clinical symptoms were correlated with the filarial infection and the parasitic infection rates (PIR) were estimated in simuliid vectors. The general M. ozzardi human prevalence rate was 13.3 percent (231/1733), of which 10.2 percent (109/1069) were from the urban area and 18.4 percent (122/664) from the rural area. The prevalence rates were higher in men (14.5 percent urban and 19.7 percent rural) than in women (6.7 percent urban and 17.2 percent rural) and occurred in most age groups. The indices of microfilaremics were higher in people > 51 years old (26.9 percent urban and 61.5 percent rural). High prevalence rates were observed in retired people (27.1 percent urban area), housewives and farmer (41.6 percent and 25 percent, respectively, in rural area). The main clinical symptoms were joint pains and sensation of leg coldness. Only Cerqueirellum argentiscutum (Simuliidae) transmits M. ozzardi in this municipality (PIR = 5.6 percent urban and 7.1 percent rural). M. ozzardi is a widely distributed parasitic disease in Coari. Thus, temporary residency in the region of people from other localities involved with the local gas exploitation might be a contributing factor in spreading the disease.

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

This study was undertaken to investigate the prevalence of Mansonella ozzardi infection and to estimate the parasitic infection rate (PIR) in simuliid black flies in the municipality of Pauini, Amazonas, Brazil. We used thick blood films to examine 921 individuals in 35 riverine communities along the Pauini and Purus Rivers. Simuliids were caught in several communities. Flies were identified, stained with haematoxylin and dissected. Overall, 44 (24.86 percent) of 177 riverines were infected in communities on the Pauini River and 183 (24.19 percent) of 744 on the Purus. The prevalence was higher in men (31.81 percent and 29.82 percent) than in women (17.98 percent and 19.18 percent) and occurred in most age groups. The prevalence increased sharply in the 28-37 (50 percent and 42.68 percent) age group and increased in the older age classes. The highest prevalence was in farmers (44 percent and 52.17 percent, respectively) in the Pauini and Purus Rivers. Only Cerqueirellum amazonicum (Simuliidae) transmits M. ozzardi in this municipality, and we found a PIR of 0-8.43 percent and infectivity rate of 0-3.61 percent. These results confirm that rates of M. ozzardi infection are high in Pauini and suggest that its prevalence may be far greater than has been previously reported due to the absence of a program for treating the population.

Current profile of Mansonella ozzardi (Nematoda: Onchocercidae) in communities along the Ituxi river, Lábrea municipality, Amazonas, Brazil

The objective of this paper was to describe the current status of Mansonella ozzardi prevalence among the inhabitants of 12 communities along the Ituxi river, in Lábrea municipality, state of Amazonas. The prevalence of M. ozzardi was determined using thick blood smears obtained by digital punctures. M. ozzardi was found in 30.23 percent of the samples collected (39/129), with similar prevalence between genders (males: 30.30 percent; females: 30.16 percent); the highest prevalence was found in homemakers (45.45 percent) followed by farmers (38.77 percent). Among age groups, males and females older than 48 exhibited the highest rates. These results show a significative increase in the prevalence when compared to a epidemiological study made 26 years ago in the same area as well as a different epidemiological profile (gender and occupation) in relation to other areas in Amazonas.

Acometimento ocular em pacientes com mansonelose / Ocular manifestations in mansonelliasis

OBJETIVOS: Avaliar as alterações oculares observadas em indivíduos com mansonelose residentes na área rural do município de Coari, AM, na região do médio Amazonas. MÉTODOS: Foi conduzido um estudo de corte transversal envolvendo 543 moradores residentes na área rural do município de Coari, na margem direita do rio Solimões. Todos os indivíduos foram submetidos a exame de gota espessa para pesquisa de microfilária e os indivíduos positivos foram submetidos a exame oftalmológico. Lesões oculares suspeitas foram biopsiadas e enviadas para exame histopatológico. RESULTADOS: Mansonella ozzardi foi encontrada no sangue periférico em 103 (18,9 por cento) indivíduos. Noventa e cinco pacientes com mansonelose foram examinados, observando ceratite puntata em 12 (11,7 por cento) destes, ceratite numular em um indivíduo (1 por cento) e esclerosante em outro (1 por cento). Biópsia de pele foi negativa em todos os indivíduos. Biópsia de conjuntiva e limbo foi realizada em cinco pacientes com mansonelose e biópsia de córnea em outros três pacientes. Duas biópsias de conjuntiva e limbo e uma biópsia de córnea foram enviadas para exame histopatológico, não sendo observadas microfilárias ou alterações sugestivas da presença destas nas peças estudadas. O restante das biópsias foi enviado para pesquisa de DNA do parasita por PCR, não se encontrando microfilária. CONCLUSÕES: Associação entre infecção por Mansonella ozzardi e lesões corneanas sem etiologia aparente foi verificada neste estudo, mas a ausência de achados específicos no exame histopatológico e a não identificação de microfilárias por PCR em lesões suspeitas põem em dúvida a o acometimento corneano na mansonelose. Estudos mais amplos de populações com alta prevalência de M. ozzardi e a realização de outros testes para identificação de microfilárias em tecido ocular são necessários para investigar a patogenicidade da microfilária ao tecido ocular.

PURPOSE: To evaluate eye manifestations in mansonelliasis patients from Coari, AM, rural area on the middle Amazonas River. METHODS: Cross-sectional study consisted of evaluation of 543 subjects from Coari rural area on Solimões River right margin. All subjects were submitted to blood test for microfilaria and the subjects who had a positive test also were submitted to skin biopsies and ophthalmologic examination. Histopathology and PCR research for microfilaria were done on eye biopsies of suspect lesions. RESULTS: Mansonella ozzardi was found in peripheral blood of 103 (18.9 percent) subjects. Ninety-five mansonelliasis patients were examined. Punctate keratitis was observed in 12 of them, nummular keratitis in one subject and sclerosing keratitis in another one. Skin biopsies were negative in all subjects. Conjunctival and limbal biopsies were done in five mansonelliasis patients and corneal biopsy in another three patients. Conjunctival and limbal biopsies of two patients and corneal biopsy of one patient showed no microfilaria or alterations due to its presence on histopathology. PCR showed no evidence of microfilaria in the other biopsies. CONCLUSION: Association between Mansonella ozzardi infection and corneal lesions with no evident etiology was observed in this study, but the lack of conclusive findings on histopathology and PCR make us doubt the corneal involvement in mansonelliasis. Large studies of high mansonelliasis prevalence populations and extensive employment of microfilaria identification tests in ocular tissue are needed to evaluate the microfilaria corneal pathogenicity.

Biting of anthropophilic Culicoides fulvithorax (Diptera: Ceratopogonidae), a vector of Mansonella perstans in Nigeria

Anthropophilic Culicoides were investigated in a rural community endemic for Mansonella perstans in Ijebu North area of western Nigeria between December 2003 and October 2004. Three hundred and fifty-nine adults of Culicoides fulvithorax collected by human bait in the morning were dissected for Mansonella perstans larvae, and 1.95% of infection rate was found. Seasonal abundance of C. fulvithorax was investigated by monthly biting rates, and showed that higher prevalence was observed in rainy season, with peak in September. Culicoides prevalence was positively correlated with rainfall and relative humidity, but not temperature. Human perceptions on the behavior of these biting midges were determined by interviewing 854 self-selected villagers, of which 86.5% of the interviewees confessed having experienced Culicoides bites. Between 76.5 and 99.1% of the various age groups complained body reactions to Culicoides bites. Itching was the most frequent body reaction. No interviewees associated Culicoides with transmission of any parasitic infections. The results showed need to adequately control Culicoides in the community.

Simuliid blackflies (Diptera: Simuliidae) and ceratopogonid midges (Diptera: Ceratopogonidae) as vectors of Mansonella ozzardi (Nematoda: Onchocercidae) in northern Argentina

Mansonella ozzardi, a relatively non pathogenic filarial parasite of man in Latin America, is transmitted by either ceratopogonid midges or simuliid blackflies. In the only known focus of the disease in north-western Argentina the vectors have never been incriminated. This study investigated the potential vectors of M. ozzardi in this area. The only anthropophilic species of these Diptera families biting man at the time of the investigation were Simulium exiguum, S. dinellii, Culicoides lahillei and C. paraensis. Using experimentally infected flies S. exiguum and both species of Culicoides allowed full development of microfilariae to the infective stage, with C. lahillei being a more competent host than S. exiguum. Based on these data, biting rates and natural infectivity rates it is probable that at the begininning of the wet season C. lahillei is the main vector of M. ozzardi and both C. paraensis and S. exiguum secondary vectors. Additionally, it was found that a single dose of ivermectin was ineffectual in eradicating M. ozzardi from infected individuals in this area

Vectores de Onchocerca volvulus y Mansonella ozzardi en Colombia / Onchocerca volvulus and Mansonella ozzardi vectors in Colombia

Los estudios en el foco colombiano de oncocercosis del Rio Micay demostraron que el desarrollo de las microfilarias de Onchocerca volvulus hasta el estadio infectivo tuvo lugar en ejemplares de Simulium Exiguum que se habian alimentado en voluntarios con infecciones naturales. Sin embargo, fue comun observar un desarrollo demorado del parasito y aproximadamente 25% de las larvas tenian una apariencia anormal. Se considera a S. Exiguum, el unico Simulium que se colecto picando al hombre durante 6 visitas al area, como el unico vector de oncocercosis en el Rio Micay aun cuando su eficiencia sea algo reducida. Algunas especies de Simulium de los grupos S. amazonicum y S. sanguineum sirven como huespedes intermediarios y probables vectores de Mansonella ozzardi en 3 regiones endemicas de Colombia. En Puerto Palacios (Rio Arquia, Antioquia), el desarrollo de la microfilaria de M. Ozzardi hasta el estadio infectivo ocurrio en S. sanguineum que habia comido sobre voluntarios con infecciones naturales. El desarrollo en S. Exiguum, la especie que se capturo mas comunmente, no paso del primer estadio en mas de 400 ejemplares de la misma area. En Santa Marta (cerca a Mitu, Vaupes), una especie aparentemente no descrita del grupo S. sanguineum demostro ser un buen huesped intermediario para M. ozzardi y fue el unico Simulido que se obtuvo picando al hombre durante la estacion seca..