Comparison of two IgG4 assay formats (ELISA and rapid dipstick test) for detection of brugian filariasis.

Brugia malayi infection is endemic in several Asian countries. Filaria-specific IgG4 antibody detection based on BmR1 recombinant antigen has been shown to be sensitive and specific for the diagnosis of brugian filariasis. Two formats of the test has been reported ie indirect ELISA (BE) and rapid dipstick test (BR). Since different test formats use different amounts of sample and reagents which may affect its sensitivity and specificity, this study was performed to compare these two test formats in the detection of B. malayi. A total of 264 blinded serum samples from India and Malaysia were employed. Group 1 comprised 164 samples from actively infected individuals and group 2 comprised 100 samples from filaria non-endemic areas. Sensitivity was 96.3% (158/164) and 90.8% (149/164) for rapid test and ELISA respectively; chi-square p=0.00. Both test formats demonstrated 100% specificity. Therefore the rapid test format was equally specific but more sensitive than the ELISA format. The ELISA format would be able to demonstrate decline in IgG4 titer post-treatment while the rapid test would be very useful for screening and diagnosis in the field.

Breast filariasis--a case report.

An unusual presentation of filariasis as a breast lump simulating breast carcinoma, in a 50 year old woman residing in Pokhara, Nepal. The case was reported on Fine Needle Aspiration Cytology and also evaluated by histopathology. Morphology of the nematode is that of Brugia species which is unusual in Nepal.

Estimation of ASO titer as an indicator of streptococcal infection precipitating acute adenolymphangitis in brugian lymphatic filariasis.

Recurrent episodes of acute adenolymphangitis (ADL) are important clinical manifestations of lymphatic filariasis which contribute significantly to the progression of lymphedema. It is increasingly being recognized that secondary bacterial infections play an important role in the etiology of ADL. We examined the role of streptococcal infection as a precipitating factor of ADL in brugian filariasis, by determining the anti-streptolysin O (ASO) titers and by isolating the causative organism wherever possible. The study population consisted of 30 patients with filariasis related ADL (Group A), 30 patients with chronic filarial edema (Group B) and 60 age and sex matched healthy adults (Group C). ASO titer was estimated by the latex agglutination method at the time of entry into the study, at the 15th day and at 3, 6 and 12 months. ASO titers were persistently elevated in 90% of patients in Group A and a portal of entry for bacterial infection was detected in all of these patients. In Group B only six patients had persistently elevated ASO titers. These patients had grade III lymphedema and three of them had monilial infections in the affected limb. In the control group none had persistently elevated ASO titers. The elevated ASO titers and the detection of a site of entry for bacteria in patients with ADL supports a streptococcal etiology for this condition.

Impact of 50 years of vector control on the prevalence of Brugia malayi in Shertallai area of Kerala state.

This article examines the long term effects of vector control on the prevalence of B. malayi infection and disease, by comparing the results of 3 earlier studies (1934, 1955, 1976) in one area of south India with a recent (1986) survey. The data indicate that disease and infection prevalence have declined continuously over the last 50 years. Infection has declined (from 21 to 2%) more markedly than disease (from 24 to 10%). Age-specific data indicate that this difference is due to the irreversibility of the clinical signs and the long term survival of diseased cohorts. The results indicate that the prevalence of clinical brugian filariasis can be reduced using vector control and that such control programmes cannot be evaluated in short term or by using crude morbidity statistics.

Alteration in Aedes togoi susceptibility to Brugia pahangi microfilariae induced by Aedes albopictus thoracic homogenate.

Refractoriness to Brugia pahangi microfilarial infection could be induced in the normally susceptible Aedes togoi mosquitoes by intrathoracic injection with crude thoracic homogenate of the refractory Aedes albopictus mosquitoes. The crude thoracic homogenate contained three Sephadex G-200 protein profiles of which the first profile showed strongest inhibition to the parasite development.

Application of biotechnology in the identification of filarial larva in mosquitoes.

Current methods for detecting and identifying filariae in mosquitoes are laborious and time consuming. With today's technology, we can reasonably expect development of rapid, sensitive and specific assays for detecting and identifying filariae in naturally infected mosquito populations. Progress in developing such assays is reviewed.

Parasitological and entomological studies on filariasis in seven villages, Serian District, Sarawak, East Malaysia.

A total of 82 persons have been found to be positive for microfilaria a sub-periodic Brugia malayi out of 1,613 examined in seven villages in Serian District. This represents an average microfilaria infection rate of 5.1% with a range of zero to 10.7%. It is found that males are more predominantly affected than females with a ratio of 3:1. It is also confirmed that Mansonia dives and M. bonneae are possible vectors for the transmission of the disease although Anopheles species cannot be ruled out owing to the small number of specimens examined. The study is confined to areas where indoor DDT spraying has been done since 1960 and only in two of the areas it has been terminated in 1966. Yet to be published data shows higher filaria infection rate than any of these villages.

Microfilaraemia survey in Vientiane, Laos.

During the period June 1977-January 1978 a microfilariaemia survey was conducted for the first time in 27 villages (population: 9,300) of Vientiane province of Laos. A total of 2,339 persons, 1,372 males, 967 females, mostly adults, were blood tested between 2000--2400 hours; one thick smear, approximately 20 c.mm, was collected from each one and stained with 10% Giemsa for 30 minutes; only one positive was detected with microfilaria of W. bancrofti in a 22-year-old male; unusually the sheath was well stained. Two cases of elephantiasis of the left leg in two middle-aged women were also diagnosed during the clinical survey. All the three cases were probably infected in the north-eastern province of Houa Phanh.

Clinical features of timorian filariasis among immigrants to an endemic area in West Flores, Indonesia.

Fifty-nine persons, who immigrated into a Brugia timori endemic area from non-filarial areas on the island of Flores, Indonesia were examined for filariasis after residing in the village for 2 to 10 years. Six persons had B. timori microfilaremia and 31 had filarial disease. The disease seems to affect immigrants from non-filarial areas severely within a relatively short period. Among those residing in the village, for 2 years, the microfilaria rate was 5% and the elephantiasis rate 21%. Selective treatment using 50 mg diethylcarbamazine per Kg body weight was given to all microfilaria (Mf) positive persons. Approximately one year later the Mf-rate by finger stick and Nuclepore filtration was 9% and 18% respectively. There was indirect indications that the Mf-rate might increase with the passage of time. However, the total filarial disease rate remained constant during the one year period. The relationship between these findings and American servicemen exposed to filariasis during World World II is briefly discussed.

A comparison of the efficiency of the Nuclepore and Millipore filtration systems for detecting microfilariae.

Using Brugia pahangi or Dirofilaria immitis as the test organisms no significant difference could be detected between Nuclepore and Millipore filters. It was found that 0.7% of microfilariae passed through the Millipore and 1% through the Nuclepore filters. No microfilariae were lost from the Nuclepore membrane during the staining process.

Studies on filariasis in the Pacific. 5. Brugia malayi filariasis in treated and untreated populations of South Borneo.

A blood survey employing membrane filter concentration (MFC) and examination of stained 20 c.mm thick blood films as diagnostic methods was carried out in Banjar Regency of South Borneo, an area of endemic B. malayi filariasis. In untreated populations the mf rate, as revealed by MFC, ranged from 23.2% for the 5-9 year old group to 43.7% for the greater than 50 year old group. For all age groups approximately one half of the microfilaraemias were of a low grade nature, diagnosed by MFC only. In a population that had been subjected to mass DEC administration 1 1/2 years prior to this survey, the MFC-diagnosed rate was 15%. Approximately two thirds of these infections were of very low density, the average density being 2.2 mf/ml.

Studies with Brugia pahangi. 11. Measurement of lymph flow in infected cats.

Rates of lymph flow in cats were measured by calculating the disappearance of radioactive colloidal gold (198Au) from the feet of (1) uninfected cats, (2) cats infected for various periods after primary infection with Brugia pahangi, and (3) cats repeatedly challenged with B. pahangi infective larvae over long periods. The results of the study showed that (1) there is great variation in gold disappearance rates in different cats in all 3 groups above, (2) the cat lymphatic system is functionally highly efficient, and (3) in a cat with lymphoedema and early elephantiasis, there was a significant impairment of gold removal from the affected foot. The study proved useful in finding lymph drainage rates in the various animals but did not, as hoped, show any pattern of lymph flow decrease which might have enabled the use of the technique as a diagnostic tool for lymphatic pathology prior to the occurrence of external clinical manifestations of filariasis.