Sensitivity of diagnostic methods for Mansonella ozzardi microfilariae detection in the Brazilian Amazon Region

BACKGROUND The human filarial worm Mansonella ozzardi is highly endemic in the large tributaries of the Amazon River. This infection is still highly neglected and can be falsely negative when microfilariae levels are low. OBJECTIVES This study investigated the frequency of individuals with M. ozzardi in riverine communities in Coari municipality, Brazilian Amazon. METHODS Different diagnostic methods including polymerase chain reaction (PCR), blood polycarbonate membrane filtration (PCMF), Knott's method (Knott), digital thick blood smears (DTBS) and venous thick blood smears (VTBS) were used to compare sensitivity and specificity among the methods. Data were analysed using PCMF and Bayesian latent class models (BLCM) as the gold standard. We used BLCM to calculate the prevalence of mansonelliasis based on the results of five diagnostic methods. FINDINGS The prevalence of mansonelliasis was 35.4% by PCMF and 30.1% by BLCM. PCR and Knott methods both possessed high sensitivity. Sensitivity relative to PCMF was 98.5% [95% confidence interval (CI): 92.0 - 99.7] for PCR and 83.5% (95% CI: 72.9 - 90.5) for Knott. Sensitivity derived by BLCM was 100% (95% CI 93.7 - 100) for PCMF, 100% (95% CI: 93.7 - 100) for PCR and 98.3% (95% CI: 90.6 - 99.9) for Knott. The odds ratio of being diagnosed as microfilaremic increased with age but did not differ between genders. Microfilariae loads were higher in subjects aged 30 - 45 and 45 - 60 years. MAIN CONCLUSIONS PCMF and PCR were the best methods to assess the prevalence of mansonelliasis in our samples. As such, using these methods could lead to higher prevalence of mansonelliasis in this region than the most commonly used method (i.e., thick blood smears).

Mansonelosis por Mansonella ozzardi en voluntarios para despistaje de malaria en la Amazon¡a peruana / Mansonelosis by Mansonella ozzardi in volunteers undergoing screening for malaria in the peruvian Amazon

Objetivos. Determinar la frecuencia, manifestaciones cl¡nicas y factores asociados a la infecci¢n por Mansonella ozzardi en voluntarios de una campa¤a de despistaje de malaria en el distrito de Alto Nanay en la selva amaz¢nica del Per£. Materiales y m‚todos. Se realiz¢ un estudio descriptivo, anal¡tico y transversal. Los participantes fueron entrevistados y examinados por un m‚dico y los datos fueron registrados en una ficha cl¡nica. El diagn¢stico de infecci¢n por M. ozzardi se realiz¢ mediante la t‚cnica de gota gruesa y frotis. Resultados. La frecuencia de mansonelosis en esta poblaci¢n fue 47,8% (IC 95%: 39,1–56,6). Mediante el an lisis bivariado se encontr¢ que el reporte de disminuci¢n de la agudeza visual o visi¢n borrosa y la presencia de tumoraciones subcut neas fueron los signos y s¡ntomas estad¡sticamente asociados con la infecci¢n por microfilarias (p<0,05). La regresi¢n log¡stica encontr¢ asociaci¢n estad¡stica para la residencia en localidades del r¡o Pintuyacu o Alto Nanay, la ocupaci¢n en lugares alejados del centro poblado, la presencia de tumores subcut neos y el engrosamiento de la piel (p<0,05).Conclusiones . Existe una elevada frecuencia de mansonelosis por M. ozzardi en el distrito de Alto Nanay, la cual se encontr¢ significativamente relacionada con ocupaciones realizadas fuera del centro poblado, residencia en localidades del r¡o Pintuyacu y lesiones cut neas.

Objectives. To determine the frequency, clinical features, and factors associated with M. ozzardi infection in volunteers of a malaria screening campaign in the district of Alto Nanay in the Amazon jungle of Peru. Materials and methods. A descriptive, analytical and cross-sectional study was performed. The participants were interviewed and examined by a physician and the data were recorded in a medical record. The diagnosis of M. ozzardi infection was performed using the method of thick blood smear and film. Results.The frequency of mansonelosis in this population was 47.8% (95% CI: 39.1 to 56.6). Through bivariate analysis we found that the report of decreased visual acuity or blurred vision and presence of subcutaneous tumors were the signs and symptoms statistically associated with the infection of microfilariae (p<0.05). Logistic regression found statistical association for residency in localities of the Pintuyacu or Alto Nanay rivers, employment in places far from the town center, the presence of subcutaneous tumors and skin thickening (p<0.05). Conclusions. There was a high number of mansonelosis by M. ozzardi in the district of Alto Nanay which was significantly related to working outside the town center, residing in the area of the Pintuyacu River, and skin lesions.

Mansonelliasis, a neglected parasitic disease in Haiti

Reported in Haiti as early as 1923, Mansonella ozzardi is still a neglected disease ignored by the health authorities of the country. This review is an update on the geographic distribution of the coastal foci of mansonelliasis in Haiti, the epidemiological profile and prevalence rates of microfilariae in people living in endemic areas, the clinical impact of the parasite on health and the efficiency of the transmission of the parasite among three Culicoides biting-midge species identified as vectors in Haiti. Additionally, interest in establishing a treatment programme to combat this parasite using a single dose of ivermectin is emphasised.

Mansonella ozzardi in the municipality of Tefé, Amazonas, Brazil, 60 years after the first report: an epidemiologic study

The prevalence of mansonelliasis was studied in the municipality of Tefé, state of Amazonas, Brazil. The prevalence (thick blood smear method) was 13.6% (147/1,078), higher in the Solimões River region (16.3%) than in the Tefé River region (6.3%). In the sampled communities in the Solimões River region, a higher density of cases was observed, as indicated by a kernel analysis (odds ratio 0.34; 95% confidence interval: 0.20-0.57). Males had a higher prevalence (χ2 = 31.292, p < 0.001) than women. Mansonella ozzardi prevalence was higher in retirees and farmers (28.9% and 27%, respectively). Prevalence also significantly increased with age (χ2 = -128.17, p < 0.001), with the highest numbers occurring in persons older than 67 years.

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. .

Reporte de cuatro casos clínicos de filariasis en Alto Nanay, Loreto / Report of four clinical cases of filariasis in Alto Nanay, Loreto

El presente estudio describe los hallazgos clínicos, parasitológicos y de laboratorio de cuatro pacientes residentes en el distrito de Alto Nanay, Maynas, Loreto, Perú; infectados con microfilarias de Mansonella ozzardi. La evaluación clínica incluyó las especialidades de oftalmología, cardiología y nefrología. En el caso 1, destaca la presencia de dos tumoraciones subcutáneas, una a nivel dorsal y la otra en el tercio inferior de la pierna izquierda; en el caso 2, la sensación de “hormigueo o frío en las piernas”; en el caso 3 se encontró asociada una infección crónica por hepatitis B y en el caso 4 una tumoración de gran tamaño en región lumbar izquierda. En los cuatro pacientes se encontró Mansonella ozzardi y eosinofilia, tres presentaron valores mayores a 20%. La tumoración en el caso 4 correspondió a una hernia de contenido intestinal. Es necesario ejecutar más estudios clínicos y evaluar su verdadero efecto patógeno, es también pertinente estudiar la diversidad genética de filarias de la Amazonia peruana.

This study describes the clinical, parasitological and laboratory findings of four patients who lived in the district of Alto Nanay, Maynas, Loreto, Peru and were infected with Mansonella ozzardi microfilariae. Clinical examinations by ophthalmologists, cardiologists and nephrologists were performed. In case 1, the presence of 2 subcutaneous lumps was the most important finding, one at dorsal level and the other in the lower third of the left leg; in case 2, there was a sensation of tingling or coldness in the legs; in case 3, an associated chronic hepatitis B infection was found, and in case 4, a large lump was detected in the left lumbar region. All 4 patients were infected with Mansonella ozzardi and had eosinophilia, 3 of them in percentages of 20%. The lump found in case 4 was due to a herniation of bowel content. Further clinical studies and an evaluation of the actual pathogenic effect of microfilariae are to be performed. A study of the genetic diversity of filariae in the Peruvian Amazon would also be important.

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.

Improvement of a PCR test to diagnose infection by Mansonella ozzardi / Adequação da técnica da PCR para diagnóstico de infecção de Mansonella ozzardi

INTRODUCTION: Mansonelliasis is caused by Mansonella ozzardi. It is widespread in the Amazon region, with a high prevalence. The common exam of thick blood smears stained with Giemsa shows low efficacy levels and has been an obstacle to diagnosing individuals with low blood parasitemia. METHODS: In order to increase diagnosis efficacy, the PCR technique was improved. RESULTS AND CONCLUSIONS: PCR demonstrated the best performance, with sensitivity and negative predictive values (NPV) of 100 percent, followed by blood filtration through membrane filters, which showed a sensitivity of 88.9 percent and a NPV of 84.6 percent, when compared to thick blood smears.

INTRODUÇÃO: A mansonelose é uma filariose causada pela Mansonella ozzardi, ocorrendo na Amazônia com prevalências de até 60 por cento. A técnica de diagnóstico habitual (hemoscopia através da gota espessa) tem baixa eficácia o para o diagnóstico de pacientes com baixa parasitemia. MÉTODOS: Neste contexto foi aperfeiçoada a técnica da PCR para seu diagnóstico. RESULTADOS E CONCLUSÕES: Quando comparada à gota espessa, a PCR apresenta sensibilidade de 100 por cento, e valor preditivo negativo (VPN) de 100 por cento mostrando eficácia bastante superior à técnica da filtração em membrana que apresenta sensibilidade de 88,9 por cento e VPN de 84,6 por cento, quando também comparada à gota espessa de sangue.

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.

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.

Ocorrência da Mansonella ozzardi (Nematoda, Onchocercidae) em comunidades ribeirinhas do rio Purus, Município de Boca do Acre, Amazonas, Brasil / Occurrence of Mansonella ozzardi (Nematoda, Onchocercidae) in riverine communities of the Purus river, Boca do Acre municipality, Amazonas State, Brazil

Este estudo teve o objetivo de estimar as prevalências de Mansonella ozzardi e calcular taxa de infecção parasitária nos simulídeos. O trabalho foi realizado em comunidades ribeirinhas do rio Purus, Boca do Acre, Amazonas, Brasil. As prevalências foram obtidas por meio do método de gota espessa de sangue obtido por porção digital. Os simulídeos coletados foram dissecados para estimar a taxa de infecção parasitária. A prevalência de M. ozzardi foi de 27,3 por cento (282/77). Foram observadas maiores prevalências nos homens (31,97 por cento) que nas mulheres (22,22 por cento), nos agricultores (48 por cento) e nos indivíduos entre: 38-47 (60 por cento), 48-57 (66,66 por cento) e 58-67 (75 por cento). A microfilaremia foi maior nos indivíduos entre 58-67 anos (média = 58,41mf/40µL), sexo masculino (41,44mf/40µL) e nos agricultores (49,94mf/40µL). Somente o simulídeo Cerqueirellum amazonicum foi encontrado infectado com taxa de infecção parasitária de 0,98 por cento.

The study aimed to estimate the prevalence of Mansonella ozzardi and calculate the parasitic infection rate in simuliid blackflies. The research was conducted in communities on the Purus River, Boca do Acre municipality, Amazonas State, Brazil. Prevalence was measured using the thick smear method. Captured blackflies were dissected to verify the parasitic infection rate. M. ozzardi prevalence was 27.30 percent (77/282). The study showed higher prevalence in men (31.97 percent) than women (22.22 percent), farmers (48.99 percent), and individuals in the 38-47 (60.00 percent), 48-57 (66.66 percent), and 58-67-year age brackets (75.00 percent). Microfilaremia was higher in individuals 58 to 67 years of age (average= 58.41mf/40µl), men (41.44mf/40µl), and farmers (49.94mf/40µl). Only the simuliid Cerqueirellum amazonicum was found infected with a parasitic infection rate of 0.98 percent.

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.

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

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 percent, 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 percent. 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.

Esse trabalho tem como objetivos estimar a prevalência de Mansonella ozzardi em comunidades indígenas do município de Pauini, Amazonas, Brasil e estimar a Taxa de Infecção Parasitária nos vetores. Foram examinados indígenas da etnia Apurinã, pelo método de gota espessa, em seis comunidades localizadas as margens e afluentes do rio Purus. A prevalência geral para M. ozzardi foi de 28,40 por cento, com maior incidência para o sexo masculino e nos indivíduos com atividade no campo (agricultores). Em relação à faixa etária, as menores prevalências foram obtidas nos indivíduos mais jovens (2-9 anos), enquanto as maiores nos indivíduos acima de 58 anos. Foram encontrados simulídeos parasitados em três comunidades, com uma Taxa de Infecção Parasitária que variou de 0,34 a 6,58 por cento. A prevalência de M. ozzardi entre os Apurinã é elevada, possivelmente relacionada às suas atividades diárias as margens dos rios, onde existe uma grande abundância dos vetores.

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.