Entomological investigations on malaria and bancroftian filariasis transmission were carried out in the endemic area of Baram District, Sarawak. The Anopheles composition, survival and infection rates of malaria and filariasis were compared in the village and 0.5 km from the village ecotype, in forested areas. Anopheles leucosphyrus, An. barbirostris and An. donaldi are the vectors for malaria and bancroftian filariasis in both ecotypes. Biting and infection rates vary, but An. leucosphyrus differed with a peak around midnight in the forested area and soon after dusk in the village setting. The parous rate of An. leucosphyrus was significantly higher in the forest ecotype (P < 0.0001); however, the proportion of 3-parous and older was not overall higher in the forest ecotype (P = 0.68). The entomological inoculation of malaria parasites by An. leucosphyrus was comparatively higher in the forested areas (P > 0.5). The implications of malaria and filariasis transmission in the forested areas in Baram District are discussed.
We describe the results of serology for parasitic infection of 250 foreign workers who were seen at the University of Malaya Medical Centre, UMMC during 7-months period. The 250 foreign workers participated included 114 from Indonesia, 142 from Bangladesh, two from Myanmar and two from Pakistan. Blood samples were taken from these workers and eight tests (amoebiasis, echinococcosis, filariasis, leishmaniasis, malaria, schistosomiasis, toxoplasmosis, and trypanosomiasis) were performed on serum. Among the 250 sera tested, 92 (36.8%) were found to be positive for at least one parasitic infection. There was one case where the serum was found positive for 5 tests. The most common antibody detected in those positive sera was antibody for toxoplasma (80.%), followed by filaria (32.8%) and amoeba (30%). Other tests showed low percentage of infection with schistosomiasias, 10%; echinococcosis, 6% and malaria, 3.6%. None of the foreign workers were found positive for leishmaniasis or trypanosomiasias.
Lymphatic filariasis is endemic in Asia. The infections persist as a major cause of clinical morbidity and a significant impediment to socioeconomic development. Its prevalence is increasing world wide, largely because of rapid unplanned urbanization in many endemic areas. It is estimated that at least 120 million people are infected. In our study on foreign workers, a total of 241 day time blood samples were collected. The countries represented were Bangladesh (134), Indonesia (103), Pakistan (3) and Myanmar(1). The tests conducted on blood samples were thick blood film for microfilaria and thin blood film for malaria and quantitation of eosinophiles using the Giemsa stain. Out of the 241 blood samples tested, one was positive for Wuchereria bancrofti and one other was positive for malaria (Plasmodium falciparum) each from Bangladesh and Indonesia respectively. As for the blood eosinophiles, 39 (16.18%) blood samples showed high eosinophilia. Fifteen (6.22%) were from Banglandesh and 24 (9.96%) were from Indonesia. The Bangladeshi male who was positive for Witcherrria bamuofti also showed eosinophilia of 22%. We believe that some of these cases with high eosinophilia, may be positive for microfilaria. We may have missed some cases because of the methodology we chose. Lymphatic filariasis is endemic in Bangladesh and Indonesia. In Malaysia W. brancrofti, especially in the cities have been eliminated. However their vectors for the transmission of W. bancrofti is rampant in the cities. With the influx of immigrants with W. bancrofti and in relation to their occupational nature, W. bancrofti may eventually be introduced into the community and change the whole facet of the disease in Malaysia.
Parasitological and serological investigations for lymphatic filariasis were performed on 450 immigrants detained at the lmmigration Centre at Semenyih, Selangor, West Malaysia. The country of origin of these immigrants were Indonesia, The Philippines, Myanmar, Bangladesh, India and Pakistan. Brugia malayi adult worm homogenate (BmAH) antigen was used for the detection of antiifilarial IgG. A monoclonal antibody-based ELISA (MAb.XC3-ELISA) specific for filarial circulating antigens and non-phosphorylcholine reactive was used to detect antigenemia in these immigrants. Parasitologically 67 (14.89 %) were positive for W. bancrofti and 54 (12.0%) for Brugia malayi. Serologically 63% had antifilarial IgG titre to the BmAH antigen. While Bancroftian filariasis is now unknown in Peninsular Malaysia, the potential of it to be reintroduced into Peninsular Malaysia by the immigrant population is discussed. KEYWORDS: Lymphatic filariasis, immigratits, antifilarial IgG, antigenemia
A rapid and selective high-performance liquid chromatographic assay for simultaneous quantitative determination of a new antifilarial drug (UMF-058, I) and mebendazole (MBZ) is described. After a simple extraction from whole blood, both compounds were analysed using a C18 Nova Pak reversed-phase column and a mobile phase of methanol-0.05 M ammonium dihydrogenphosphate (50:50, v/v) adjusted to pH 4.0, with ultraviolet detection at 291 nm. The average recoveries of I and MBZ over a concentration range of 25-250 ng/ml were 92.0 +/- 7.7 and 84.4 +/- 4.4%, respectively. The minimum detectable concentrations in whole blood for I and MBZ were 7 and 6 ng/ml, respectively. This method was found to be suitable for pharmacokinetic studies.
The known filaricides, suramin and diethylcarbamazine citrate, were tested against subperiodic Brugia malayi infection in the leaf-monkey, Presbytis cristata. As expected, intravenous suramin at 10 mg/kg daily x 5 days or 17 mg/kg weekly x 5 weeks, did not show any microfilaricidal activity, but substantially reduced the recovery of live adult worms to 50.6% and 13.6% of controls respectively. Oral diethylcarbamazine citrate at 6 mg/kg daily x 6 or 10 days reduced final microfilarial counts to 30% of initial counts four weeks post-treatment and adult worm recovery was reduced to 4.5% and 0% of controls respectively. Although the antifilarial activity of these drugs against the infection in this non-human primate model appears to be similar to that seen in man, these results have to be confirmed using larger groups of animals.
Four Presbytis cristata were treated with oral ivermectin at the same time as the subcutaneous inoculation of 100 infective larvae monthly for three months. Two animals given 0.2 mg/kg monthly and two others given 0.3 mg/kg monthly as well as three control animals became patent for microfilaraemia. However, only 1% of the infective dose was recovered as adult worms from animals in the higher drug dosage group compared to 8.2% and 6.2% in the lower dosage and control groups respectively.
Adult worms of the rural strain of Wuchereria bancrofti in Peninsular Malaysia obtained from a successful experimental transmission in an immunosuppressed Macaca fascicularis are described for the first time. Although the worms, especially females, were slightly smaller, they were similar in morphology to those of the periodic and non-periodic W. bancrofti previously described.
This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.
Breinlia booliati exhibited nocturnal subperiodicity in its natural host, Rattus sabanus in contrast to experimentally infected laboratory-reared albine rats which showed irregular fluctuations of microfilariae throughout the 24 hour cycle. All the infected albino rats showed a prepatent period between 11-14 weeks postinoculation. Three patterns of microfilaraemia were discerned during the course of infection 38/49 rats displayed a single peak, 4/49 displayed 2 peaks about 12-15 weeks apart and 7/49 showed a sustained high plateau-like pattern of microfilaraemia. Cortisone had no effect on microfilarial levels when administered to rats near postpatency and some at postpatency.
Accurate identification of filarial parasites in mosquitoes poses a major problem for the coordination of filariasis control programs. Traditional methods are tedious, and some are not specific enough to give satisfactory results. Amplification of specific gene sequences by primer-directed polymerase chain reaction (PCR) has been increasingly utilized as a diagnostic tool. However, current protocols for the extraction of parasite DNA from mosquito samples are tedious and could lead to failure of PCR amplification. We demonstrate that the use of Chelex is an efficient method for DNA extraction from mosquitoes and the parasite and that PCR amplification with primers specific for Brugia malayi yields a band of the expected size. The PCR products were transferred to a nylon membrane with Southern blotting, and a B. malayi-specific digoxigenin-labeled probe confirmed the sequence similarity of the PCR-amplified fragment and increased the sensitivity of the PCR assay. Use of this probe enabled us to detect PCR-amplified product from B. malayi even when a product was not visible on an ethidium bromide-stained agarose gel. This increased sensitivity allowed us to detect the parasite in the heads of mosquitoes.
Thirteen strains among 3 species of entomopathogenic bacteria were tested against 3 medically important mosquito species in French Polynesia. Two strains of Bacillus thuringiensis were highly toxic to Aedes polynesiensis, Aedes aegypti, and Culex quinquefasciatus. Six of 7 strains of Bacillus sphaericus tested were highly toxic to Cx. quinquefasciatus but not to the Aedes spp. Clostridium bifermentans serovar. malaysia was more toxic to Ae. polynesiensis than to the other 2 species. Entomopathogenic bacteria merit field testing for larval mosquito control in French Polynesia.
A preliminary field study was undertaken to evaluate the efficacy of a mosquito trap; Mosquito Killing System (MKS) in
capturing mosquitoes and other insects. MKS has an automatic activation by the use of a photocell. It is also supplemented
with carbon dioxide and heat as attractants for mosquitoes and other insects. Three units of MKS were employed at three
different locations within two study sites for ten days. The mosquitoes and other insects that were trapped in MKS were
collected and morphologically identified daily in the laboratory. A total of 1,928 mosquitoes and other insects were
trapped in all units of MKS. High numbers of mosquitoes (93.05%), particularly Aedes sp. and Culex sp. were captured
from MKS. Among these, Culex quinquefasciatus (91.81%) was most abundant species collected. Only 0.84% of Aedes
aegypti and Aedes albopictus trapped in MKS. Female mosquitoes (83.44%) were found to be more attracted to MKS
compared to male mosquitoes of various species. These findings illustrated the potency of MKS utilization in surveillance
and control activities of Cx. quinquefasciatus; a nuisance mosquito and also potential vector of urban brancroftian
filariasis in Malaysia.
The periodicity of the microfilariae of Brugia malayi was studied in 9 human carriers from Shin-san Ri, Seong-san Myon, Cheju Island. The periodicity pattern was markedly nocturnal and the peaks were observed between 21:30 p.m. and 5:30 a.m. The average peak count was 1:30 a.m. and the percentage of peak count at this time was 95.3. The ratio of minimum of the average peak count percentage to the maximum was 8.3. The periodicity pattern of B.malayi in Cheju Island was compared with that in Inland and no differences were found between two forms. From the above observations, it was concluded that the periodicity of B. malayi in Korea is markedly nocturnal and closely resembles that in the strain of Penang, Malaya.