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.
R. sabanus and R. muelleri are very common in the lowland forests of Malaysia. In nature they are infected with Breinlia sp. and D. ramachandrani. In an attempt to determine whether they are also susceptible to subperiodic B. malayi and thereby being potential reservoirs of infection of the disease, 24 R. muelleri and 17 R. sabanus were experimentally infected with the parasite. Results show that although they can support the full development of the parasite, they are poor hosts. This confirms the observation that in Malaysia natural infection of Rattus spp. with the parasite has not been seen. These rats therefore are probably not important in the zoonotic transmission of subperiodic B. malayi in Malaysia.
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.
The Temiars are a tribe of negroid pygmies of basically Proto-Malaysian affinities. Field-work in the Malaysian jungle provided some observations on the sleep-wakefulness cycle of two young Temiar adults. This cycle was monophasic circumstances permitting. Their rest-activity cycle at night was similar in the jungle and in the laboratory. Polygraphic total night-sleep recordings were made with both of them in the EEG laboratory in the Hospital Besar in Kuala Lumpur. The eye-movement frequencies of PS were compared with those from young adults of the West. Although the differences were not statistically significant, the Rem-densities of the Temiars were constantly at the low side. The significance of the results are being discussed.
The Noctuid Calpe [Calyptral] eustrigata Hmps. was reported as a skin-piercing blood-sucking moth for the first time in Malaya (Bänziger, 1968) and is so far the only lepidopteran proved to suck blood by means of a piercing act. A few field observations and the description of the piercing behaviour of caged moths were given. Apart from a taxonomic study of the genus Calpe (Berio, 1956), a single record (Büttiker, 1969) and some notes on the moth's proboscis and possible evolutionary pathway (Bänziger, 1970, 1971, 1972) to our knowledge no other data have been published on the moth after its description as a new species (Hampson, 1926). The life cycle is completely unknown. From the scanty museum specimens available, it appears that the species inhabits South and Southeast Asia. A closely related, though less rare species, the fruit-piercing C. thalictri Bkh., has been used for a detailed study of the piercing mechanism likely to be adopted by Calpe (Bänziger, 1970); the feeding turned out to be as unusual as the feeding habits. Little or nothing is known about other Calpe species. C. eustrigata is not the only adult lepidopterous parasite of mammals. Lachryphagous ("eye-frequenting") moths feed as "marginal" parasites upon eye-secretions of ungulates, elephants and occasionally man (Shannon, 1928; Reid, 1954; Büttiker, 1964, 1967; Bänziger, 1966). Arcyophora species and the eulachryphagous Noctuid Lobocraspis graseifusa Hmps. which apparently feeds exclusively upon eye discharges, are suspected as vectors of eye diseases (Guilbride et al., 1959, Büttiker, 1964; Bänziger, 1972). While no lachryphagous moth is able to suck blood by a piercing act, there are a number of facultative lachryphagous moths which lick up the blood freely present at wounds, or that excreted anally by mosquitoes (Bänziger, 1969, 1972). Because of the scientific interest in C. eustrigata, research has been carried out to investigate different biological aspects of the species in Malaysia, Thailand. Laos and Indonesia (May 1971-May 1973). The first account presented here will be continued with a paper (in prep.) on the piercing mechanism and soon, it is hoped, with more information on the physiology, life cycle and medical importance of the moth.
Rhythmic flashing behavior of synchronous flashing fireflies from Malaysia and New Guinea was studied. The "circa second" firefly pacemaker has characteristics analogous to circadian rhythms, such as entrainment, phase shifting, limits of entrainment, fringe entrainment, and effects of the light:dark ratio on phase. The three species studied show different phase-response curves; a light pulse causes a large phase shift in one firefly species (Pteroptyx cribellata) but small phase shifts in others (Pteroptyx malaccae and Luciola pupilla). Comparative studies of the phase angle differences between the animal's flash and the flash of a controlled light source suggest at least two different mechanisms of attaining synchrony: 1) by cycle-to-cycle phase shifting of a stable oscillator; 2) by changing the underlying period (tau) of a variable oscillator.
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.
Women in an urban, Malay population reported menstrual period lengths that tended to coincide with the lengths of the calendar months in which the periods began. This pattern may be related to the calendar-month pay periods for the population.
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.
Hematological changes were monitored in the leaf-monkey, Presbytis cristata, infected experimentally with 200 subperiodic Brugia malayi infective larvae. Prepatent periods were 54-86 days and peak microfilarial geometric mean counts (GMCs) were 1324 per ml blood. Total leukocyte and differential counts were measured at pre-infection, and then at weakly intervals before and during patency. Blood eosinophil level increased to about thrice the initial level at 3 weeks post-infection and this was maintained for the next 13 weeks before it started to rise again, increasing to more than 5 times the initial level at 20 weeks post-infection. The observed pattern of eosinophilia is probably related to the level of microfilaremia and the destruction of microfilariae in the spleen. There was no significant change in the total leukocyte counts during the period of observation.
CGI 18041, an adduct of benzothiazol isothiocyanate N-methyl piperazine, was evaluated for its antifilarial properties in subperiodic Brugia malayi infected Presbytis cristata. Animals experimentally infected with 200-400 subperiodic Brugia malayi infective larvae, were matched according to microfilaria density, infective dose, and duration of infection. They were then randomly assigned to various treatment and control groups. The compound was suspended in 1% Tween 20 in distilled water, sonicated, and then fed to monkeys using a stomach tube. Control animals received an equivalent volume of drug diluent. CGI 18041 at a single oral dose of 50 mg/kg had complete adulticidal and microfilaricidal activities against subperiodic B. malayi in P. cristata. It was also extremely effective at a single dose of 25 mg/kg, the final geometric mean microfilaria count being 1.6% of initial level, and only 1.0% of the infective dose was recovered as live adult worms at autopsy 6 weeks post-treatment. In control animals, these were 226.9% and 5.56% respectively.
The effect of permethrin impregnated bednets on Anopheles maculatus Theobald was studied in four villages in Pos Betau, Pahang, Malaysia from August 1990 to July 1992. Collections of mosquitos were carried out indoors and outdoors from 1900 to 0700 hours. All mosquitos were dissected for sporozoites and parity. In May 1991 two villages received bednets impregnated with permethrin at 0.5 g/m2 and two villages received placebo bednets. There was a significant difference in the sporozoite and parous rates between the treated and control villages after the distribution of bednets (p < 0.05). There was no significant difference in the bites/man/night of An. maculatus between the pre and post treatment periods in the control villages. However there was a significant difference in bites/man/night between pre and post treatment in the treated villages (p < 0.001).
Twelve species of Anopheles were collected by using cow-baited net trap in a malarial endemic village in northern Peninsular Malaysia. Anopheles maculatus which is the main malaria vector with its densities were related to drought. An. aconitus, An. kochi and An. philippinensis were less susceptible to P. falciparum and P. vivax infection, and are not considered important in falciparum or vivax malaria transmission. Biting activities of An. kochi and An. vagus were primarily active after dusk and steadily declined after midnight. An. maculatus and An. aconitus showed biting activities throughout the night but An. maculatus showed two peaks of biting activity in the first half of the night.
The study compared the effectiveness of a single dose of diethylcarbamazine (DEC) (6mg/kg) with the standard regimen of 6 doses (total 36 mg/kg) in mass chemotherapy for the control of brugian filariasis. Mass chemotherapy with single-dose DEC was instituted in one area and standard dose in the other and treatment was repeated after one year. Parasitological surveys were conducted before, and 3, 7 and 12 months after treatment. Pretreatment characteristics were not significantly different between the 2 treatment areas. There was a significant reduction in microfilaraemia prevalence rate from 24.7% to 14.7% at 12 months and to 6.8% at 19 months in the single dose area and from 22.8% to 9.6% at 12 months and to 2.7% at 19 months with the standard dose. Maximum reduction was at 7 months after treatment with both regimens. There was also significant progressive reduction in mean microfilarial density from 4.39 +/- 20.37 to 0.89 +/- 4.16 per 60 microL in the single-dose area and from 4.43 +/- 17.31 to 0.75 +/- per 60 microL in the standard dose area. There was a greater reduction of both microfilarial prevalence and density using the standard regimen but it was not statistically significant. Thus, a single dose of DEC is as effective as the standard dose in controlling periodic brugian filariasis.
Studies were carried out to observe the species composition of mosquitos and to determine the vectors responsible for the transmission of filariasis in Grik, Perak, Malaysia. A total of 2,155 mosquitos belonging to 7 genera and 30 species were collected. Anopheles donaldi comprised 24.1% of the collection. Twelve out of 519 An. donaldi were infected with L3 larvae of Brugia malayi. The peak biting time was around 23.00-24.00 hours. The infective bites per month ranged from 0 to 6.3.