A pilot study on the status of lymphatic filariasis in a rural community of Bihar.

A pilot study of lymphatic filariasis was conducted in two contiguous villages of Patna district in Bihar situated at the side of the river Ganges, known to be endemic for lymphatic filariasis, to study present status of transmission parameters of filariasis. Of the 1872 persons examined, 8.4% were found asymptomatic but microfilaraemic. Morbidity pattern due to filarial infection showed an increase with advancement of age and significantly high in males as compared to female (p < 0.001). Acute and chronic filarial disease was observed as 0.5% and 9% respectively. Microfilaria was found in 10% of acute and 11.2% of chronic filarial cases. The Mf rate was found to be 9.9% in males and 9.0% in females respectively. The parasite species was identified as W. bancrofti. The vector fauna surveyed show highest prevalence of vector species of Cx. quinquefasciatus (43%) in both domestic as well as predomestic area in the community. Other species like Cx. vishnui and Ma. uniformis were also seen. Each household and predomestic area was searched for mosquito fauna at night. The infection rate in vectors was found to be 14% and infectivity rate (L3) was 8%. The filariasis cases detected in the study were treated with 12 days course of DEC 6 mg/kg body weight.

Culex quinquefasciatus in Phitsanulok as a possible vector of nocturnally periodic Wuchereria bancrofti transmission in Myanmar immigrants.

The present study was undertaken in order to study whether Culex quinquefasciatus collected in Phitsanulok Province can be an insect host for the development of Wuchereria bancrofti larvae. W. bancrofti infected blood from Myanmar workers in Mae Sot, Tak Province was fed to mosquitoes by using the artificial membrane feeding. An infection of W. bancrofti was found with the highest density of L3 in the mosquito thorax on the 14th day after feeding. The infection rate also correlated to the density of microfilaria found in the donor's blood. Our results showed that Cx. quinquefasciatus in Phitsanulok is a possible vector of nocturnally periodic W. bancrofti.

A morfologia do intestino médio de Culex quinquefasciatus Say, 1823 e sua interação experimental com microfilárias de Litomosoides chagasfilhoi Moraes Neto, Lanfredi e De Souza, 1997 e Wuchereria bancrofti (Cobbold, 1877) Seurat, 1921 / The morphology of the midgut of Culex quinquefasciatus Say, 1823 and its interaction with experimental microfilariae of Litomosoides chagasfilhoi Moraes Neto, Lanfredi and De Souza, 1997 and Wuchereria bancrofti (Cobbold, 1877) Seurat, 1921

Analisamos a morfologia do intestino médio do mosquito Culex quiquefasciatus de região endêmica e a sua interação com as microfilárias de Wuchereria bancrofti (agente da filariose humana) e de Litomosoides chagasfilhoi (agente de filariose de roedores). O intestino médio está dividido em regiões torácica e abdominal como visto em outras espécies de mosquitos. Porém, o intestino médio torácico é formado por dois tipos celulares: células principais e basais; e o intestino médio abdominal por três tipos: células principais clara e basais. Existe uma rede muscular organizada revestindo externamente o órgão, a qual sofre mudanças irreversíveis no intestino médio abdominal após o repasto sangüíneo. A estrutura da matriz peritrófica e a sua formação induzida pela alimentação sangüínea são distintas das demais espécies de mosquitos. O L. chagasfilhoi invade o intestino médio entre 1h e 3h após o repasto infectivo, enquanto que a W. bancrofti entre 30 minutos e 5 horas com o maior número de invasão nas primeiras 2 horas. O L. chagasfilhoi preferencialmente invade o intestino médio abdominal enquanto que a W. bancrofti invade o intestino médio torácico, principalmente perto da região abdominal. Ambas espécies de microfilárias cruzam o intestino médio através do espaço intercelular, causando hipertrofia e extrusão de uma a duas células epiteliais. A perda da bainha pelas microfilárias de ambas espécies não é um pré-requisito para a evasão do intestino. Etapas subseqüentes do ciclo da W. bancrofti, tais como, a melanização na hemocele e a invasão precoce da musculatura de vôo foram também observadas. Não foi possível observar tais etapas nos mosquitos infectados com L. chagasfilhoi porque eles morreram poucas horas após a invasão do intestino médio. Estas diferenças no processo de interação das espécies de microfilárias provavelmente estão relacionados com a capacidade vetorial do mosquito.

A morfologia do intestino médio de Culex quinquefasciatus Say, 1823 e sua interação experimental com microfilárias de Litomosoides chagasfilhoi Moraes Neto, Lanfredi e De Souza, 1997 e Wuchereria bancrofti (Cobbold, 1877) Seurat, 1921

Analisamos a morfologia do intestino médio do mosquito Culex quiquefasciatus de região endêmica e a sua interação com as microfilárias de Wuchereria bancrofti (agente da filariose humana) e de Litomosoides chagasfilhoi (agente de filariose de roedores). O intestino médio está dividido em regiões torácica e abdominal como visto em outras espécies de mosquitos. Porém, o intestino médio torácico é formado por dois tipos celulares: células principais e basais; e o intestino médio abdominal por três tipos: células principais clara e basais. Existe uma rede muscular organizar revestindo externamente o órgão, a qual sofre mudanças irreversíveis no intestino médio abdominal após o repasto sangüíneo. A estrutura da matriz peritrófica e a sua formação induzida pela alimentação sangüínea são distintas das demais espécies de mosquitos. O L. chagasfilhoi invade o intestino médio entre 1h e 3h após o repasto infectivo, enquanto que a W. bancrofti entre 30 minutos e 5 horas com o maior número de invasão nas primeiras 2 horas. O L. chagasfilhoi preferencialmente invade o intestino médio abdominal enquanto que a W. bancrofti invade o intestino médio torácico, principalmente perto da região abdominal. Ambas espécies de microfilárias cruzam o intestino médio através do espaço intercelular, causando hipertrofia e extrusão de uma a duas células epiteliais. A perda da bainha pelas microfilárias de ambas espécies não é um pré-requisito para a evasão do intestino. Etapas subseqüentes do ciclo da W. bancrofti, tais como, a melanização na hemocele e a invasão precoce da musculatura de vôo foram também observadas. Não foi possível observar tais etapas nos mosquitos infectados com L. chagasfilhoi porque eles morreram poucas horas após a invasão do intestino médio. Estas diferenças no processo de interação das espécies de microfilárias provavelmente estão relacionados com a capacidade vetorial do mosquito

A preliminary analysis of Wuchereria bancrofti microfilarial antigens for potential use in diagnosis.

Several antigens from the microfilarial stage of Wuchereria bancrofti have been identified using immunoblots of microfilarial antigens and screening with immune sera and tropical pulmonary eosinophilia (TPE) sera. This analysis revealed an array of antigens with apparent molecular weights of 14kDa, 35kDa, 42kDa, 63kDa, 88kDa, 97kDa and 200kDa. Among these only the 14kDa and 42kDa antigens were consistently recognized by most of the immune sera. A 132kDa antigen was recognized only by TPE sera. Analysis of rabbit immune sera revealed that the 42kDa antigen was shared by two developmental stages of W. bancrofti, namely L3 and mF. This antigen could become a potential vaccine candidate. The 14kDa antigen seems specific for the microfilarial stage and therefore could be a diagnostic marker for active infection. The 132kDa antigen could aid in the diagnosis of TPE.

Occurrence of asymptomatic microscopic haematuria in a filarial endemic area of Orissa, India.

To determine the frequency of occurrence of asymptomatic microscopic haematuria in filarial endemic area of Orissa, where the mf rate and disease rate were observed to be 14.8% and 37.2% respectively, clinical examination, night blood smear examination, morning midstream urine examination were conducted on 697 persons-randomly selected from all age groups in 8 villages of Puri tehsil. Out of them, 15.6% were found to have asymptomatic haematuria (Grade I-14.7%, Grade II-0.6%, Grade-III 0.3%). The prevalence of asymptomatic microscopic haematuria was observed to have positive statistical correlation with mf status (P < 0.001), filarial antigenaemia (Ag) (P < 0.001), antibody (Ab) (P < 0.001) and circulating immunocomplex antigen (CIC-Ag) (P < 0.001). The prevalence was also found to be increased with the progression of the disease process i.e. from endemic normal to chronic manifestations. None of the cases having Grade-II and III haematuria cases revealed any gross renal pathological lesions, when subjected to special investigations like X-ray, IVP, cystoscopy and urethroscopy.

In vitro cultivation of third stage larvae of Wuchereria bancrofti to fourth stage: influence of some physico-chemical factors.

It has been reported that third stage larvae (L3) of Wuchereria bancrofti strain from Jakarta, molted to the fourth stage (L4) in vitro, in a simple culture medium supplemented with 10% human serum. In the present study, this culture medium has been used to examine the effects of some physico-chemical parameters on larval growth, development and molting of Wuchereria bancrofti from India. Lymph at 10% concentration enhanced the in vitro survival time of larvae. Molting of larvae from L3 to L4 stage has been obtained using human fetal lung cells in cellular co-culture and as a source of conditioned medium. Given these improvements in the medium supplementation, it has been observed that the age of L3s (duration of L3s maintenance within the mosquitos) is one of the most important parameters for the development of L3s in vitro. No molting was observed when one day L3s were used whereas, molting occurred with one or two weeks old L3s. On the contrary, when more than 3 weeks old L3s were used molting failed to occur even though duration of survival of L3s was improved and in this case, most of the larvae were degenerated.

A simple deterministic model for host-parasite relationship in Wuchereria bancrofti infection & its relevance to parasite regulation in human host.

A deterministic immigration-death model, which reflects the population dynamics of W. bancrofti in human host has been applied to study the relationship between vector and human infections. Application of the model showed that the rate of acquisition and loss of human infection were approximately equal (L = 0.130 and M = 0.129). The relationship of infective resting density (IRD) in vector population with maximum intensity (Imax) of infections and microfilaria prevalence (MFP) in human population were examined by using the least squares polynomial regressions. The fifth order polynomial regressions were found to be adequate to describe the observed pattern (Imax vs IRD: R2 = 0.8464, P = 0.0015; MFP vs IRD: R2 = 0.7246, P = 0.019). The observed relationships indicated that at an infective resting density of 0.26 per man hour or above, the density-dependent factors start regulating the human infections, which showed a declining trend, following this level.

Development of Brugia malayi in Mongolian gerbils previously exposed to Wuchereria bancrofti.

Twelve Mongolian gerbils, Meriones unguiculatus, were infected with 100 third-stage larvae of Wuchereria bancrofti. One month later these animals, along with 4 control animals, were given 100 third-stage larvae of Brugia malayi. Eleven of the 12 experimental animals and the 4 controls survived, and 8 of the experimental animals and all of the controls demonstrated microfilaremia after 3 months. The animals were killed at 6-months post-infection and examined for parasites. One W. bancrofti larva was found in one of the experimental animals, and 15% of the B. malayi given were recovered as adults from the testes, viscera, and carcass. Thirty-eight percent of the worms given to the controls were recovered from the testes, viscera, and pelt. The worms from the experimental animals also appeared to be smaller. This study suggests that gerbils are able to develop partial resistance to Brugia malayi following a previous infection with Wuchereria bancrofti.

Attempt to culture Wuchereria bancrofti in vitro.

Third-stage larvae of Wuchereria bancrofti recovered from laboratory raised Aedes togoi and Anopheles maculatus fed on a human volunteer were recovered by mass dissection methods and introduced into in vitro culture. LLC-MK2 cells were used as feeder cells, and the culture medium consisted of RPMI-1640 buffered with Hepes and sodium bicarbonate and supplemented with human AB serum. The third-stage larvae molted as early as 12 days and those surviving had all molted by 16 days. The fourth-stage parasites averaged in length from 1.4 mm to a maximum of 1.8 mm. Some larvae remained alive in culture as long as 40 days and while the worms were distorted in fixation, possible primodial cells of a spicule could be visualized in the rectal region. The cuticle also appeared to be separating in the posterior end. Although complete development was not achieved, it seems that with a continuing effort, success could be obtained using this culture system with feeder cells.

Further studies on the development of Wuchereria bancrofti in laboratory animals.

In an attempt to obtain a small animal laboratory model for Wuchereria bancrofti Mongolian gerbils and hamsters were infected with third-stage larvae of strains of the parasite from Indonesia and China. Gerbils were necropsied at 7 to 591 days and larvae recovered up to 219 days. The third molt occurred on or before 10 days and worms found after 14 days were in the fourth stage. More worms were recovered early in the infection (7 to 30 days) than in older infections. The worms were usually recovered from the testes, pelt and carcass and heart and lungs. An adult male worm was recovered on one occasion from the lung of a gerbil at 92 days. The parasite was also found to develop in hamsters with results similar to those in gerbils. Gerbils and hamsters were given antithymocyte sera before and after infection and more worms were recovered and the worms larger in size in some treated animals. Continued studies with geographic strains of W. bancrofti in various animals should be encouraged in order to find a small laboratory animal model for the parasite.