Interruption of lymphatic filariasis transmission in Manaus, a former focus of Wuchereria bancrofti in the Western Brazilian Amazon / Interrupción de la transmisión de la filariasis linfática en Manaos, anteriormente un foco de Wuchereria bancrofti en la Amazonia occidental de Brasil / Interrupção da transmissão da filariose linfática em Manaus, anteriormente um foco de Wuchereria bancrofti na parte leste da Amazônia brasileira

ABSTRACT Objective. To confirm the absence of Wuchereria bancrofti autochthonous cases in Manaus, a former focus of lymphatic filariasis in the Western Brazilian Amazon. Methods. A field survey was carried out in 2016 using immunochromatographic rapid tests (ICT card) for the detection of circulating filarial antigens in blood. The sample included a group of 3 000 schoolchildren aged 6 to 10 years enrolled in schools from different urban areas of Manaus (including the former lymphatic filariasis focus in the city) and a group of 709 adolescents and adults, between the ages of 11 and 85 years, born and raised in different areas of Manaus. Results. All of the individuals tested negative for W. bancrofti antigen. Conclusions. Although Manaus was once considered endemic, this focus no longer seems to be active for lymphatic filariasis transmission. The results of this study could support the certification by the World Health Organization of the lymphatic filariasis transmission elimination exercise in Brazil.

RESUMEN Objetivo. Confirmar la ausencia de casos autóctonos de Wuchereria bancrofti en Manaos, anteriormente un foco de filariasis linfática en la Amazonia occidental de Brasil. Métodos. En el 2016 se llevó a cabo una encuesta en el terreno con pruebas rápidas inmunocromatográficas (tiras inmunocromatográficas) para detectar antígenos filáricos circulantes en sangre. La muestra constó de un grupo de 3 000 escolares de 6 a 10 años matriculados en escuelas de diferentes zonas urbanas de Manaos (incluida la zona que anteriormente era el foco de filariasis linfática en la ciudad) y de un grupo de 709 adolescentes y adultos, de edades comprendidas entre 11 y 85 años, nacidos y criados en diferentes áreas de Manaos. Resultados. Todas las personas dieron negativo en la prueba de antígeno de Wuchereria bancrofti. Conclusiones. Aunque hubo un tiempo en que Manaos se consideraba zona endémica, parece que este foco de transmisión de la filariasis linfática ya no está activo. Los resultados de este estudio podrían brindar apoyo a la certificación de la Organización Mundial de la Salud respecto de los esfuerzos realizados en Brasil para eliminar la transmisión de la filariasis linfática.

RESUMO Objetivo. Confirmar a ausência de casos autóctones de Wuchereria bancrofti em Manaus, anteriormente um foco da filariose linfática na parte leste da Amazônia brasileira. Métodos. Uma pesquisa de campo foi realizada em 2016 com o uso de teste rápido por imunocromatografia (cartão ICT) para detecção de antígenos de microfilárias circulantes no sangue. A amostra estudada consistiu de um grupo de 3 000 crianças escolares entre 6 e 10 anos de idade matriculados em escolas de diferentes áreas da zona urbana de Manaus (englobando a área anteriormente com o foco de filariose linfática) e um grupo de 709 adolescentes e adultos entre 11 e 85 anos de idade nascidos e crescidos em diferentes áreas de Manaus. Resultados. Todos os indivíduos pesquisados tiveram teste negativo para o antígeno da W. bancrofti. Conclusões. Apesar de Manaus ter sido anteriormente uma área endêmica, parece que não existe mais foco ativo de transmissão da filariose linfática na cidade. Os resultados deste estudo podem servir para embasar a certificação pela Organização Mundial da Saúde da eliminação da transmissão da filariose linfática no Brasil.

Detection of Wuchereria bancrofti DNA in paired serum and urine samples using polymerase chain reaction-based systems

The Global Program for the Elimination of Lymphatic Filariasis (GPELF) aims to eliminate this disease by the year 2020. However, the development of more specific and sensitive tests is important for the success of the GPELF. The present study aimed to standardise polymerase chain reaction (PCR)-based systems for the diagnosis of filariasis in serum and urine. Twenty paired biological urine and serum samples from individuals already known to be positive for Wuchereria bancrofti were collected during the day. Conventional PCR and semi-nested PCR assays were optimised. The detection limit of the technique for purified W. bancrofti DNA extracted from adult worms was 10 fg for the internal systems (WbF/Wb2) and 0.1 fg by using semi-nested PCR. The specificity of the primers was confirmed experimentally by amplification of 1 ng of purified genomic DNA from other species of parasites. Evaluation of the paired urine and serum samples by the semi-nested PCR technique indicated only two of the 20 tested individuals were positive, whereas the simple internal PCR system (WbF/Wb2), which has highly promising performance, revealed that all the patients were positive using both samples. This study successfully demonstrated the possibility of using the PCR technique on urine for the diagnosis of W. bancrofti infection.

Cross-reaction of antigen preparations from adult and larval stages of the parasite Setaria equina with sera from infected humans with Wuchereria bancrofti

Crude antigenic preparations from Setaria equina were used in ELISA and Western blotting to examine cross-reaction with human sera from areas endemic for bancroftian filariasis. Sera from normal subjects from non-endemic areas were included as negative controls. Cross-reaction was found between 5. equina antigens and antibodies in the sera of Wuchereria bancrofti-infected patients, with the highest levels observed between sera of chronic infected patients and Setaria spp. crude female worm surface antigen [CFSWA]. In the absence of active transmission of Setaria spp. infection, CFWSA is useful to detect chronic W. bancrofti infection before patients become symptomatic, particularly when chronic patients are known to be amicrofilaraemic. In the presence of active 5. equina infection, antigens from the adult and microfilaraemic stages showed the highest degree of cross-reaction with human sera

Avaliação da acurácia de diferentes testes laboratoriais no diagnóstico da filariose em crianças e adolescentes / Evaluation of the accuracy of different laboratory tests for the diagnosis of filariasis in children and adolescents

Apesar de a filariose linfática (FL) ser considerada uma doença de adultos, estima-se que 22 milhões de crianças 15 anos de idade estejam infectadas no mundo. A Organização Mundial da Saúde tem recomendado o monitoramento da infecção nessa população. Este estudo teve como objetivo comparar a acurácia dos métodos parasitológicos e imunológicos no diagnóstico da filariose bancroftiana em escolares. O estudo foi desenvolvido em escolares, com idade entre 4 e 15 anos, residentes em três bairros do município de Olinda - Pernambuco, Brasil. As amostras de sangue capilar e venoso foram coletadas entre 23:00 e 1:00 hora da manhã. Em seguida, as amostras de sangue venoso foram guardadas para posterior realização das técnicas de filtração, concentração de Knott, Og4C3 - ELISA. Amostras de sangue capilar foram obtidas para confecção das lâminas de gota espessa e realização do teste rápido de imunocromatografia (ICT). As médias de densidade de microfilaremia foram calculadas em escala logarítmica. A acurácia dos testes foi avaliada em relação ao padrão-ouro (filtração). A especificidade do Og4C3 e ICT foi estimada utilizando a equação de Staquet et al. (1981). Um total de 805 escolares foi examinado. As médias de antigenemia filarial foram mais elevadas entre as crianças residentes nos bairros de alto da conquista e alto da bondade. As cargas parasitárias e os níveis de antigenemia não variaram com idade e sexo. A prevalência de microfilaremia pela técnica de filtração, de 5,2 por cento, foi a mais elevada em relação às demais técnicas parasitológicas. A prevalência de antigenemia filarial pelo teste Og4C3 foi de 17,4 por cento. Na comparação da acurácia dos testes em relação ao padrão-ouro, as técnicas de gota espessa e Knott apresentaram valores de sensibilidade de 85,2 por cento, inferiores aos testes ICT e Og4C3, que foi de 100 por cento. Conclui-se que as técnicas de filtração e Og4C3 são as mais apropriadas para a avaliação de transmissão em áreas com programas de eliminação em andamento.

Comparison of tests for the detection of circulating filarial antigen (Og4C3-ELISA and AD12-ICT) and ultrasound in diagnosis of lymphatic filariasis in individuals with microfilariae

Significant advances were made in the diagnosis of filariasis in the 1990s with the emergence of three new alternative tools: ultrasound and tests to detect circulating antigen using two monoclonal antibodies, Og4C3 and AD12-ICT-card. This study aimed to identify which of these methods is the most sensitive for diagnosis of infection. A total of 256 individuals, all male and carrying microfilariae (1-15,679 MF/mL), diagnosed by nocturnal venous blood samples, were tested by all three techniques. The tests for circulating filarial antigen concurred 100 percent and correctly identified 246/256 (96.69 percent) of the positive individuals, while ultrasound detected only 186/256 (73.44 percent). Of the circulating antigen tests, ICT-card was the most convenient method for identification of Wuchereria bancrofti carriers. It was easy to perform, practical and quick.

Evaluation of Og4C3 antigen ELISA as a tool for detection of bancroftian filariasis under lymphatic filariasis elimination programme.

Diagnosis of Lymphatic Filariasis by microscopic examination of thick blood films (TBF) collected between 8.30 pm to 12 midnight, though highly specific is operationally problematic. We evaluated the TropBio Og4C3 serum ELISA as a tool for detection of W. bancrofti microfilaria carriers using Dried Blood Spots (DBS). The study was carried out in two parts (i) to test the sensitivity and specificity of the ELISA test for detection of circulating filarial antigen (CFA) in microfilaria (Mf) carriers vis-à-vis the conventional thick blood film (TBF) microscopy and its persistence in different categories of individuals during the course of disease viz., Endemic normals (n=51), microfilaria (Mf) carriers (n=27), acute cases (n=27), chronic cases (n=50) and a control group of non-endemic normals (n=48) using sera samples and ii) to study the utility of finger prick Dried Blood Spots (DBS) collected on filter paper for detection of Mf carriers and its comparison with another antigen detection assay, the Immunochromatographic test (ICT).Considering the non-endemic normals and microfilaria carriers, the ELISA test was found to have 100% sensitivity and 94.12% specificity for detection of Mf carriers in sera samples. The CFA was absent in majority of the subjects tested under other categories with a positivity of 7.8% among endemic normals, 11.12% among acute cases, 7.84% among chronic cases and 6.25% among nonendemic normals. Comparison of finger prick DBS and sera samples by ELISA vis-à-vis the ICT, carried out on Mf carriers (n=91) and endemic normals (n=97), showed a positivity of 88 (96.7%) in DBS as against 86 (94.5%) in sera samples and 88 (96.7%) by ICT, amongst Mf carriers, with a statistically significant correlation in antigen units between sera and DBS samples (r = 0.959, p = 0.000) amongst the microfilaria carriers. Out of 97 endemic normals, 19 (19.6%) sera and 17 (17.5%) DBS samples tested positive by ELISA while as 12(12.4%) tested positive by ICT, again with a statistically significant correlation between the antigen units in sera and DBS samples (r = 0.942, p = 0.000). DBS prepared from 25 microl of blood were found to be as sensitive as 50 microl for antigen detection. Antigen positivity detected from DBS collected during day and night from known microfilaria carriers (n=27) showed a statistically insignificant difference (p = 0.125) and a significant correlation in antigen units (r = 0.820 and p = 0.013).In view of the comparable results of ELISA, ICT and TBF microscopy, it is concluded that the TropBio Og4C3 ELISA using finger prick DBS can be used as an alternate to TBF microscopy for detection of bancroftian Filariasis under the LFE programme.

A focus of lymphatic filariasis in a tea garden worker community of central Assam.

A survey for lymphatic filariasis was conducted among tea garden workers of central Assam. Of the 656 night blood samples examined, 31 were found positive for Wuchereria bancrofti parasite (microfilaria rate 4.7%). Microfilaria rate was higher in male (7.3%) than females (2.1%). Culex quinquefasciatus was incriminated as vector mosquito.

Evaluation of a single oral dose of diethylcarbamazine 300 mg as provocative test and simultaneous treatment in Myanmar migrant workers with Wuchereria bancrofti infection in Thailand.

We assessed the efficiency of oral diethylcarbamazine (DEC) 300 mg as a provocative test on blood examination 30 minutes after administration, while gauging the overall infection rate in Myanmar migrant workers with Wuchereria bancrofti infection who enrolled for work permits in Thailand in 2002, using circulating filarial antigens (CFA) assays, the NOW ICT Filariasis card test and the Og4C3 ELISA as reference. Overall infection rates of 0.3% (95% CI=0-0.7%), 4.2% (95% CI=1.8-6.5%) and 5.9% (95% CI=3.2-8.7%) by three diagnostic tests, respectively, were observed. Among three different location groups of Myanmar population sample tested, there were no statistically significant differences in the overall infection detection rates. When either the ICT card test or the Og4C3 ELISA was used as a reference, the specificity and positive predictive value of the DEC-provocative day test was the same, 100%. The sensitivities were 25.0% (95% CI = 0.5-49.5%) and 17.6% (95% CI = 0-35.8%) on the ICT and ELISA tests, respectively. The negative predictive values were 96.8% (95% CI = 94.8-98.9%) and 95.1% (95% CI = 92.6-97.6%), respectively. In three microfilaremic persons followed-up monitored at 8-weeks DEC post-provocation, there were 6 x 10(-1) and 7 x 10(-1) decreases in microfilaremia and antigenemia. These findings suggested that, unlike the CFA assays, the DEC-provocative day test is unsuitable for the diagnosis of active W. bancrofti infection in the population tested, and for gauging current infection prevalence. The treatment would likely be beneficial to reduce microfilaremia and antigenemia.

Filariose bancroftiana em áreas urbanas do Estado de Alagoas, nordeste do Brasil: estudo em populaçäo geral / Bancroftian filariasis in urban areas of Alagoas State, Northeast Brazil: study in general population

Com objetivo de estudar a situaçäo da filariose linfática em Alagoas, foi realizado um inquérito hemoscópico na populaçäo geral de áreas urbanas das três diferentes regiöes fisiográficas do estado. Dos 101 municípios, foram pesquisados aleatoriamente 10, sendo a bancroftose detectada somente na capital, Maceió. Em um estudo seccional feito com a populaçäo geral de 4 bairros desta cidade foram examinados 10.973 indivíduos sendo detectados 226 microfilarêmicos, com prevalências nos bairros variando de O a 5,4 por cento. Tanto a prevalência de microfilarêmicos como a microfilaremia média foram significativamente maiores em indivíduos do sexo masculino. Entre os examinados näo nascidos em Maceió, o tempo de residência na área endêmica foi significativamente maior entre microfilarêmicos que entre amicrofilarêmicos. Baseado nestes dados, medidas de controle já foram implementadas visando a eliminaçäo da filariose linfática na regiäo

A study of filarial transmission in a non-endemic area of Pathankot (Punjab).

A filariasis survey was conducted in July 1998 in Pathankot town of Punjab covering a population of 28, 041. A total of 2136 blood smears were collected from migratory and local inhabitants. Microfilaria (Mf) rate and mean Mf density was 1.19 and 15.05 respectively. Disease rate was nil. All the 20 microfilaria carriers detected were known to hall from filaria endemic areas of different states. Mf rate was highest in 20-49 years age-group, whereas Mf density was high in younger age group. Wuchereria bancrofti was the only infection encountered. 10 Men Hour Density of Culex quinquefasciatus ranged between 343 in the North Command unit to 400 in an engineering unit. A total of 339 female Culex quinquefasciatus were dissected. None was found positive for human microfilaria parasite, thus negating any indigenous filariasis transmission in this town. These findings were compared to earlier surveys in the same area and other non-endemic areas. Non-endemic areas continue to be non-endemic for filariasis despite considerable increase in MF rate among migratory population and vector density.

Evaluation of recombinant chitinase antigen in serological diagnosis and surveillance of lymphatic filariasis.

Apply recombinant chitinase fusion protein antigen, enzyme-linked immunosorbent assays examined anti-filarial antibodies and evaluated of useful value in serological diagnosis and surveillance of lymphatic filariasis. The test jirds were immunized and infected by chitinase and B. malayi third stage larvae respectively. Functional protein molecular of chitinase was analyzed by SDS-PAGE, Western blot. The result shown that jirds from microfilaremia (mf) and donors with Mf were directly to react with chitinase antigen that positive rate was 100%, but Mf-xt antigen was only 80%. Normal jirds and persons sera from unepidemic control donors all were negative. False positives of 5% and 20% reacted with chitinase and Mf-xt antigens respectively. The results indicate that recombinant chitinase antigen is suitable for detection of active occult or patent lymphatic filariasis with daytime blood samples in residents of endemic areas, is easy to be performed and inexpensive.

Filariasis and blood groups.

BACKGROUND. Using modern statistical techniques, we investigated the controversial relationship between lymphatic filariasis and blood groups in a very large number of patients. METHODS. The ABO blood group, microfilaraemia and symptomatic disease status of 1444 persons was determined. The association between the filarial status and ABO blood group was studied by the Chi-square test and the method of logistic regression by fitting a model. This method simultaneously tested for association of factors such as blood groups and age with the occurrence of parasitaemia or filarial disease. RESULTS. The ABO blood groups were not risk factors in the occurrence of patent parasitaemia or filarial disease though age was associated with the occurrence of microfilaraemia and symptomatic disease. CONCLUSION. ABO blood groups are not associated with the occurrence of bancroftian filariasis.

Lymphatic filariasis in a recently described endemic area in Marinduque, Philippines.

Marinduque has never been considered endemic for filariasis. The disease was suspected when a high incidence of scrotal enlargement was noted in three villages. On April 25-26, 1991, a field survey was conducted in these villages. The objectives were: 1) to confirm the existence of filariasis, 2) to determine its age and sex distribution, 3) to gain insights on its prevalence and on the periodicity of the parasite. Daytime and nocturnal blood films were collected from both sexes aged 5 years and above. They were examined for microfilaria. Dried up smears were examined after staining. A total of 297 individuals comprising 23% of the area's population were studied. Microfilaremia was demonstrated in 47 individuals or 16% of those examined. Among the positive cases, 32 or 68% were males. Individuals 15-49 years old accounted for 28 or 60% of all the cases discovered. The prevalence rate for the study area was 37/1000 population. Out of 146 daytime smears, 18 or 12% demonstrated microfilariae. Of the 224 nocturnal smears, 37 or 17% were positive. Parasitologists at the Department of Health identified the parasite to be Wuchereria bancrofti. The study established the presence of filariasis in Marinduque. Males and young adults are predominantly afflicted. A non-periodic strain of parasite is possibly involved. Further investigations of the parasite and the vectors are recommended.

Status of lymphatic filariasis in some select slum clusters of Delhi.

Filaria surveys conducted in some select slum clusters namely Hari Nagar, Yamuna pusht near Vijaya Ghat along the Ring Road and Timarpur in Delhi during 1989, 1991 and 1992 respectively, covering a population of approximately 5000 slum dwellers revealed the presence of bancroftian microfilaria (mf) carriers and disease cases. The mf and disease rates (per cent) in these three slum areas were in the order of 6.3, 2.2, 3.7 and 1.4, 0.5 and 0.1 respectively. The mf density varied from 3.1 to 12.3 per 20 cumm. blood. High ten man hour densities of Culex quinquefasciatus (581) in Yamuna pusht followed by (355) in Timarpur were recorded during entomological investigations. Hari Nagar accounted for least ten man hour density of Cx. quinquefasciatus (160), because collection was made during winter months (November-December). The dissection of Cx. quinquefasciatus did not reveal any human filarial infection except in Yamuna pusht where out of 139 only one Cx. quinquefasciatus was found infective.

Efficacy of bi-annual administration of DEC in the control of bancroftian filariasis.

The efficacy of bi-annual administration of DEC at the dose of 6 mg/kg body weight was evaluated on the microfilaraemia prevalence, density and vector filarial infection rates. Administration of four doses (4 x 6 mg/kg) of DEC significantly (P < 0.05) reduced the microfilaria rate of the community from 6.02 per cent to 2.31 per cent, microfilaria density from 0.66 to 0.17 and infectivity rate of the vector population from 0.8 per cent to 0.39 per cent.

Hematological changes in subperiodic Brugia malayi infection of the leaf-monkey, Presbytis cristata.

Hematological changes were monitored in the leaf-monkey, Presbytis cristata, infected experimentally with 200 subperiodic Brugia malayi infective larvae. Prepatent periods were 54-86 days and peak microfilarial geometric mean counts (GMCs) were 1324 per ml blood. Total leukocyte and differential counts were measured at pre-infection, and then at weakly intervals before and during patency. Blood eosinophil level increased to about thrice the initial level at 3 weeks post-infection and this was maintained for the next 13 weeks before it started to rise again, increasing to more than 5 times the initial level at 20 weeks post-infection. The observed pattern of eosinophilia is probably related to the level of microfilaremia and the destruction of microfilariae in the spleen. There was no significant change in the total leukocyte counts during the period of observation.

Investigacao sobre a passagem transplacentaria de microfilarias de Wuchereria bancrofti em recem-nascidos de maes microfilaremicas / Investigation on transplacental passage of Wuchereria bancrofti microfilariae in newborns of microfilaremic mothers

A ocorrencia de microfilarias circulantes de Wuchereria bancrofti foi pesquisada em 304 gestantes da Unidade Mista Prof. Barros Lima e do Hospital das Clinicas da Universidade Federal de Pernambuco pelo Centro de Pesquisas Aggeu Magalhaes. A microfilaremia materna foi investigada pela filtracao de sangue venoso, sendo encontrados 13 casos positivos (4,2 por cento). A pesquisa de microfilarias no sangue do cordao umbilical de suas criancas foi negativa (6/13), assim como no sangue periferico destas ate 72 horas pos-parto e com 6 meses de vida. As amostras de leite coletadas destas maes tambem nao apresentaram microfilarias. Os autores sugerem que a ocorrencia de lesoes placentarias seja um possivel fator envolvido na passagem transplacentaria de microfilarias, e que a exposicao in utero a microfilarias e/ou antigeno filarial possam influenciar a resposta a uma infeccao filarial adquirida posteriormente, sendo importante o acompanhamento clinico e laboratorial de criancas expostas previamente a antigenos filariais em periodos precoces do desenvolvimento humano.

Prevalence of Wuchereria bancrofti infection in some coastal villages of Ganjam, Orissa.

The endemicity of filariasis was assessed in 42 villages of coastal Keluapalli PHC in Ganjam District of Orissa. Prevalence was found to vary greatly between extreme coastal and subcoastal villages. The infection was non existent in 12 coastal villages. Age and sexwise distribution of filariasis cases have been analysed and presented.