A study of malayan filariasis in Lubuk Mumpo and Datar Lebar villages in Lais Regency, North Bengkulu, Sumatera, Indonesia.

Filariasis surveys at Lubuk Mumpo and Datar Lebar, Bengkulu, Sumatera, showed microfilarial rates of 23.9% and 30% respectively. Periodicity studies showed the parasite to be nocturnally periodic B. malayi with a periodicity index of 82.17. However, unlike the Malaysian form of periodic B. malayi, 44-100% of the microfilariae in thick blood smears were sheathed. Mansonia annulata, M. bonneae, M. dives, M. uniformis and Anopheles nigerrimus are probably involved in the transmission of the disease. B. malayi infections were seen in 7.1% of domestic cats and 20% of Macaca fascicularis examined. In addition Edesonfilaria malayensis is reported for the first time in Indonesia, 60% of 5 M. fascicularis being infected.

Studies on Malayan filariasis in Bengkulu (Sumatera), Indonesia with special reference to vector confirmation.

In an endemic focus of Brugia malayi in Bengkulu, Indonesia the microfilariae rate was 25%. The microfilariae showed nocturnal periodicity. Domestic cats in the same area were found to harbour B. pahangi, with a microfilariae rate of 23%. In the study area, the most prevalent man-biting Mansonia mosquitoes were Mn.bonneae (41%), followed by Mn.annulata (27%), Mn.uniformis (25%) and Mn.dives (7%). More Mansonia mosquitoes were collected outdoors than indoors between 1800-2200 hours. Natural infections with infective larvae of Brugia spp. were found in Mn.bonneae, Mn.dives, Mn.uniformis, Mn.annulata, and An.nigerrimus. Experimental infection studies revealed that Mn.annulata, Mn.bonneae, Mn.uniformis, An.nigerrimus and An.peditaeniatus permit the development of infective larvae. Under experimental condition, the vectorial competence is high in Mn.bonneae, intermediate in Mn.uniformis and low in An.hyrcanus group. It is concluded that the principal vectors of periodic B.malayi in the study area in Bengkulu are four Mansonia species (Mn.annulata, Mn.bonneae, Mn.uniformis and Mn.dives), and that the potential vectors include two Anopheles species (An.nigerrimus and An.peditaeniatus). This is the first record of Mn.bonneae being a vector of periodic B.malayi in Indonesia.

Rodent and scrub typhus survey in a ricefield at Kramat Tunngak area, Tanjung Priok, Jakarta, Indonesia.

Trapping of small mammals in a ricefield at Kramat Tunggak around Tanjung Priok in Jakarta city, was carried out from July 1977 through June 1978. Of three species of rodents, R.argentiventer was found to be the predominant species in the ricefield. R.r.diardii was an intermittent resident, and the presence of R.norvegicus was interesting observation. S.murinus, a house shrew, was also present. R.argentiventer was the dominant species during the periods when the rice grains were available as a source of food. Infestation with Gamasid mites and non-vector chiggers was found common in all rodent species examined. R. argentiventer was the only species found infested with the classical scrub typhus vector (L. (L.) deliense). The density and mean chigger-load of the scrub typhus vector chiggers were found to be high in stages 4 and 5 of the ricefields when the micro-habitats were favourable. The oriental rat flea (X. cheopis) was found infesting all species of rodents.

Vectors of scrub typhus and their hosts on a mature oil palm estate.

L. (L.) deliense was the predominant vector of scrub typhus in a mature oil palm estate, but a small number of L. (L.) fletcheri (0.1% from rodents) and L. (L.) vivericola (0.02% from rodents and 8.0% from black plates) was also collected. Although good correlation between L. (L.) deliense collected from rodents and from black plates was not established, either method may serve as a general indicator of population fluctuations over a period of time. For the most part, the vectors of scrub typhus were limited to litter piles, and thus, the possibility of contracting scrub typhus within this type of habitat was minimal.

Rickettsia tsutsugamushi infections in chiggers and small mammals on a mature oil palm estate.

An epidemiological study in a mature oil palm estate in Peninsular Malaysia has demonstrated a low prevalence of R. tsutsugamushi infection in small mammals. The direct fluorescent antibody technique for assaying infections in chiggers proved more sensitive than mouse inoculation. Most infections in both chiggers and rodents were caused by the Karp strain.

Presence of antibodies to scrub typhus and murine typhus in dogs from Selangor, Peninsular, Malaysia.

Dog sera, collected from different communities throughout Selangor, Peninsular Malaysia, were investigated for the presence of antibodies to R. tsutsugamushi and R. typhi. Scrub typhus antibodies were present in animals from the rural areas only, whereas murine typhus antibodies were observed in equal numbers of dogs from both rural and metropolitan areas. Greater percentage of dogs from suburban areas had demonstrable antibody titers to murine typhus than from the urban area.

The freshwater snail lymnaea rubiginosa as an experimental host of Angiostrongylus malaysiensis: a preliminary report.

Preliminary studies have shown that Lymnaea rubiginosa, a common fresh-water snail in Peninsular Malaysia, which is easily colonized and reared in the laboratory, is a capable experimental intermediate host for Angiostrongylus malaysiensis. Overall 73% of the snails tested became infected following 6 hours exposure to infective rat faeces. Higher infection rates, up to 100%, and heavier worm loads, occurred among the larger sized snails. Snail attrition was low except when very heavy worm loads were acquired.

Digenetic trematodes from rats, squirrels and tree shrews in Malaysia.

Neodiplostomum (Conodiplostomum) Brachylaima, Ectosiphonus and Euparadistomum are reported for the first time from small mammals in Malaysia. New host and locality records are given for Echinostoma, Achillurbainia, Beaveria, Odeningotrema, Leipertrema, Athesmia, Skrjabinus and Zonorchis. Possible-life-cycles of the parasites are discussed in relation to the ecology and feeding habits of the hosts.

The first authentic record of Angiostrongylus cantonensis Chen, 1935 Peninsular Malaysia.

Angiostrongylus cantonensis Chen, was recovered from a field rat, Rattus tiomanicus from the East Coast of Peninsular Malaysia. The parasite constitutes the first reported record occurring in this country. Morphological character of the parasite are compared with the original description of A. cantonensis by Chen (1935), A. cantonensis from Formosa and A. malaysiensis from Malaysia.