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.

Gonotrophic discordance in Culex quinquefasciatus (Diptera: Culicidae) in the city of São Paulo, Brazil

Abstract INTRODUCTION: This study aimed to assess the occurrence of gonotrophic discordance in females of Culex quinquefasciatus in São Paulo, Brazil. METHODS: Resting females were collected monthly for 8 months. Females of Cx. quinquefasciatus were identified, and their midgut and ovaries were dissected. RESULTS: Two hundred females were dissected, out of which, 27.5% were nulliparous and 57% were parous. Most females had no blood in the midgut, but gonotrophic discordance was found in 21% females. CONCLUSIONS: Females of Cx. quinquefasciatus showed a high parity rate and gonotrophic discordance, which could favor the vector capacity of this species.

Semi analytical method for solving lymphatic filariasis epidemic model

In this paper, we present a deterministic model on the transmission dynamics of Lymphatic Filariasis. Non-Standard Finite Difference Method (NSFDM) is employed to attempt the solution of the model. The validity of the NSFDM in solving the model is established by using the computer in-built classical fourth-order Runge-Kutta method. The comparism between Non-Standard Finite Difference Method solution and Runge-Kutta (RK4) were performed which were found to be efficient, accurate and rapidly convergence

Mosquito identification and molecular xenomonitoring of lymphatic filariasis in selected endemic areas in Giza and Qualioubiya governorates, Egypt

Lymphatic filariasis is a vector-borne health problem that has been focally endemic in Egypt for centuries. The chief vectors of transmission are Culicinae species. Control measures in the form of mass drug administration of DEC citrate treatment have been implemented in Nile delta for almost a decade. This study aimed to identify the prevalent mosquito species in endemic areas in Giza and Qualioubiya governorates and to monitor Wuchereria bancrofti infection by detecting the parasite DNA in collected mosquitoes. Adult mosquitoes were collected using light traps hung indoors. Microscopic examination was performed to identify and examine the morphologic characters of mosquitoes. Female Culex mosquitoes were subjected to semi-nested PCR to detect filarial DNA targeting repetitive DNA sequences [pWb12 repetitive region] specific for W.bancrofti

The results revealed 3 species of mosquitoes Culex pipiens, Culex pusillus and Culex quinquefasciatus with the predominance of Culex pipiens [85.7%]. Wuchereria bancrofti DNA was not detected in any of the collected mosquito pools. With the progress of elimination programme in Nile Delta, follow up studies with larger sample size are recommended as the predominance of Culex pipiens the main lymphatic filariasis vector remains a risk of transmission in such areas

Xenomonitoramento molecular para avaliação da infecção vetorial por Wuchereria bancrofti em áreas endêmicas de filariose linfática na Região Metropolitana do Recife/PE / Molecular xenomonitoring for the evaluation of vector infection rate by Wuchereria bancrofti in endemic areas for lymphatic filariasis in Metropolitan Region of Recife/PE

A filariose linfática (FL) ou bancroftiana é uma doença parasitária causada por Wuchereria bancrofti, um verme filarial transmitido no Brasil pelo mosquito Culex quinquefasciatus. De acordo com a Organização Mundial de Saúde (OMS) esta doença afeta 120 milhões de pessoas em 58 países. Portanto, para enfrentar a FL, a OMS lançou um programa global para eliminá-la até 2020 e o Brasil tornou signatário dessa proposta criando o Plano Nacional de Eliminação da Filariose Linfática (PNEFL). Atualmente, a Região Metropolitana do Recife (RMR) é uma área de importante transmissibilidade e, assim, foi preconizado o Tratamento Coletivo (TC) da população com o medicamento Dietilcarbamazina (DEC) e o controle vetorial para reduzir a transmissão da doença. Como ferramenta complementar, desde a vigilância até a verificação da eliminação, o xenomonitoramento molecular (baseado na PCR para detecção de W. bancrofti em mosquitos) é um importante método não invasivo para monitorar indiretamente se a transmissão de larvas de W. bancrofti está ocorrendo na população humana. A fim de verificar a taxa de infecção vetorial no mosquito C. quinquefasciatus pela W. bancrofti foram coletadas 43.981 fêmeas do mosquito em doze localidades na RMR. Além disso, foi desenvolvido um novo protocolo (PCR duplex) para o diagnóstico de infecção vetorial e o número ideal de fêmeas por pools foi estabelecido. Os resultados mostraram que Linha do Tiro (Recife), uma área com alto índice de microfilaremia na população humana, apresentou status de transmissão durante o TC com uma taxa de infecção vetorial de 0,80 por cento, diferente das outras localidades com transmissão reduzida não foram detectados pools positivos. Portanto, observa-se que onde o TC é conduzido a taxa de infecção vetorial tende a ser reduzida. O xenomonitoramento molecular é um indicador importante para avaliação da eficiência das estratégias do PGEFL implantado em áreas endêmicas, até que ocorra a certificação da interrupção do ciclo de transmissão da filariose.

Survey of Bancroftian filariasis infection in humans and Culex mosquitoes in the western Brazilian Amazon region: implications for transmission and control

Introduction The aim of this work was to identify possible lymphatic filariasis foci in the western Brazilian Amazonian that could be established from the reports of Rachou in the 1950s. The study was conducted in three cities of the western Brazilian Amazon region - Porto Velho and Guajará-Mirim (State of Rondônia) and Humaitá (State of Amazonas). Methods For human infection evaluation thick blood smear stained with Giemsa was used to analyze samples collected from 10pm to 1am. Polymerase chain reaction (PCR) was used to examine mosquito vectors for the presence of Wuchereria bancrofti DNA. Humans were randomly sampled from night schools students and from inhabitants in neighborhoods lacking sanitation. Mosquitoes were collected from residences only. Results A total 2,709 night students enrolled in the Program for Education of Young Adults (EJA), and 935 people registered in the residences near the schools were examined, being 641 from Porto Velho, 214 from Guajará-Mirim and 80 from Humaitá. No individual examined was positive for the presence of microfilariae in the blood stream. A total of 7,860 female Culex quinquefasciatus specimens examined were negative by PCR. Conclusions This survey including human and mosquito examinations indicates that the western Amazon region of Brazil is not a focus of Bancroftian filariasis infection or transmission. Therefore, there is no need to be included in the Brazilian lymphatic filariasis control program. .

Evaluation of toxicity of plant extracts against vector of lymphatic filariasis, Culex quinquefasciatus.

Background & objectives: Conventional insecticides are generally used as larvicides to control Culex quinquefasciatus, vector of lymphatic filariasis. This study was undertaken to evaluate the larvicidal activity of some potential larvicidal plants leaf extracts against Cx. quinquefasciatus larvae. Methods: The toxic effects of petroleum ether leaf extracts of plants viz., Argemone mexicana (Mexican prickly poppy), Clausena dentata (Dentate), Cipadessa baccifera (Rana bili), Dodonaea angustifolia (Hop bush) and Melia dubia (Pride of India) were evaluated under laboratory conditions in individual and in combination against 3rd - 4th instar larvae of Cx. quinquefasciatus. Results: The results indicated that among the selected plants, A. mexicana showed maximum larvicidal activity with an LC50 value of 48.89 ppm. Its toxicity was enhanced when the extract was mixed (1:1) with that of C. dentata as the LC50 value became 28.60 ppm indicating synergistic action of A. mexicana. Interpretation & conclusions: Our results showed high larvicidal potential in A. mexicana leaf extract, and it also showed additive effect when mixed with C. dentata extract.

Development of physiological resistance and its stage specificity in Culex quinquefasciatus after selection with deltamethrin in Assam, India

The study investigated the development and stage specificity of physiological resistance to insecticides in a colony of Culex quinquefasciatus Say (Diptera: Culicidae) mosquitoes, which are vectors of bancroftian filariasis in India, after selection with deltamethrin. Resistance was selected by exposing the larvae to the concentration of deltamethrin that caused 50 percent mortality in the tested population (i.e., LC50). Under continuous selection pressure, the LC50 increased steadily in subsequent generations. The estimated LC50 for the F0 generation was 0.409 μg/L; the LC50 first displayed a substantial increase in the F5 generation (5.616 μg/L) and reached 121.902 μg/L in the F10 generation. The objective of this study was to establish a deltamethrin-resistant colony to develop a research programme that will study the evolution of physiological resistance patterns and stage-specific resistance responses in Cx. quinquefasciatus larvae and adults under laboratory conditions. An approximately 298-fold increase in resistance was recorded after 10 generations, as evidenced by the resistance ratio (RR50). The progress and effect of the selection pressure in the adult stage was monitored with the World Health Organisation (WHO) diagnostic test. The mortality, as observed using the WHO diagnostic test, declined significantly from the F5 generation (85 percent) onwards and the highest rate of survival (65 percent) was observed in the F10 generation.

Situaçäo da filariose bancroftiana na Regiäo Metropolitana do Recife: estudo em uma área endêmica no Município de Jaboatäo dos Guararapes, Pernambuco, Brasil / The occurrence and distribution of lymphatic filariasis in Greater Metropolitan Recife: the case of an endemic area in Jaboatäo dos Guararapes, Pernambuco, Brazil

Este artigo apresenta os resultados do inquérito epidemiológico que estudou a ocorrência e a distribuiçäo da filariose bancroftiana no Distrito de Cavaleiro, Município de Jaboatäo dos Guararapes, Pernambuco. O desenho de estudo empregado foi o seccional. Foram analisados 9.520 indivíduos da populaçäo residente nos 12 bairros que compöem o distrito. Deste total, detectou-se 213 microfilarêmicos (2,2 por cento). Cerca de 91,7 por cento dos bairros pesquisados apresentaram casos de infecçäo filarial, com prevalências variando de 0 por cento a 5,15 por cento. A populaçäo masculina foi a mais acometida pela infecçäo, com 64,3 por cento dos casos (p < 0,05). Verificou-se, também, a existência de positividade em todas as faixas etárias examinadas. Esses resultados indicam que a filariose bancroftiana permanece como um problema de saúde pública na regiäo, necessitando de medidas de controle e atençäo dos administradores e planejadores de saúde

Bloodmeal microfilariae density and the uptake and establishment of Wuchereria bancrofti infections in Culex quinquefasciatus and Aedes aegypti

The relationship between ingestion of microfilariae (mf), production of infective larvae (L3) and mf density in human blood has been suggested as an important determinant in the transmission dynamics of lymphatic filariasis. Here we assess the role of these factors in determining the competence of a natural vector Culex quinquefasciatus and a non vector Aedes aegypti to transmit Wuchereria bancrofti. Mosquitoes were infected via a membrane feeding procedure. Both mosquito species ingested more than the expected number of microfilariae (concentrating factor was 1.28 and 1.81 for Cx. quinquefasciatus and Ae. aegypti, respectively) but Cx. quinquefasciatus ingested around twice as many mf as Ae. aegypti because its larger blood meal size. Ae. aegypti showed a faster mf migration capacity compared to Cx. quinquefasciatus but did not allow parasite maturation under our experimental conditions. Similar proportions of melanized parasites were observed in Ae. aegypti (2.4 per cent) and Cx. quinquefasciatus (2.1). However, no relationship between rate of infection and melanization was observed. We conclude that in these conditions physiological factors governing parasite development in the thorax may be more important in limiting vectorial competence than the density of mf ingested.

Seasonal abundance & biting behaviour of Mansonia annulifera, M. uniformis & M. indiana & their relative role in the transmission of malayan filariasis in Shertallai (Kerala state).

Three species of Mansonia (Mansonioides) mosquitoes, viz., Mansonia annulifera, M. uniformis and M. indiana were recorded in the Shertallai region of Kerala state. M. annulifera and M. uniformis were recorded throughout the year while M. indiana was seasonal and in small numbers. Their indoor resting density was 3.29, 0.25 and 0.10 per man per h and the man biting density was 24.67, 12.74 and 0.47 per man per night respectively. Vector density fluctuated through seasons and reached a peak during the monsoon/post-monsoon period when there was an increase in the breeding surface area and a relatively higher survival of the adults. The biting tendency of M. annulifera and M. indiana was relatively more indoors (endophagic) whereas it was outdoors (exophagic) for M. uniformis. All these mosquitoes showed a predilection towards cattle, with varying degrees of zoophily. The relative abundance, man biting behaviour and a higher transmission potential indicate that M. annulifera is a more potent vector of Brugia malayi, than M. uniformis in this region.

Colonization of Mansonia dives Schiner in a field insectary.

Successful colonization of Mansonia dives, the principal vector of subperiodic Brugia malayi was established in a field insectary. Mean egg clusters laid on Eichhornia crassipes, Pistia stratiotes, Homalomena cordata and polystyrofoam strips were 12.0, 10.4, 9.5 and 13.7 respectively. However, the mean number of first instar larvae hatched from each egg cluster laid by females on the three plant substrates (range 51.1 to 58.6) was higher than that laid on the polystyrofoam strips (41.8). There were no significant differences in the success pupation and adult emergence rates among the three host plants used as attachment substrates. Adult emergence occurred at a mean of 10.8 days. The first adult emergence was observed at the 25th day after hatching and continued till the 50th day. The 50% mortality rates for the adults were estimated as 8 days for the males and 14 days for the females. The mean gonotrophic cycle ranged from 3.8 to 4.3 days with a mean of 4.04 days. 63.6% of Ma. dives females oviposited in a medium of rat dung and water. The mean incubation period of eggs ranged from 5.2 to 6.5 days with a mean of 5.7 days. The biology of Ma. dives and Ma. bonneae is briefly compared.

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.

A mathematical analysis of various factors involved in transmission of bancroftian filariasis in Pondicherry.

The variation of clumping factor in microfilaraemia among different age groups was observed in Pondicherry for 1981 and 1986. The clumping factor was minimum in the age group 0-5 yr and it was maximum in 16-20 yr group in 1981 and 21-25 yr in 1986. The variation in clumping factor resembled the changes in microfilaria (mf) rate. Multiple linear regression analysis showed that the multiple correlation between mf rate and the other parameters i.e., median microfilarial density (MFD50), clumping factor in human population, and, infection rate and infectivity rate in vector population was highly significant. The relationship between filariometric indices in human host and vector population may provide the basis on which a mathematical model on transmission of filariasis could be developed.