The life cycle of 5 generations of Leptotrombidium (L.) fletcheri infected with Rickettsia tsutsugamushi and reared under ambient temperatures in Malaysia was presented and compared with a colony reared at a constant 27 degrees C (Neal and Barnett, 1961). In general our colony had a longer generation time (average of 54 days from engorged larvae to adult compared with 37 days) and produced fewer eggs (average of 127.9 compared with 900.0) than the comparison colony. Possible factors causing these differences are discussed.
Numbers of L. (L.) deliense larvae were determined in adjacent habitats over a 16 month period. Both R. argentiventer and R. tiomanicus were highly efficient hosts for L. (L.) deliense. R. argentiventer was host to significantly greater numbers of chiggers per rat than was R. tiomanicus. The 2 habitats were similar in numbers of chiggers collected. No consistent correlation was apparent between numbers of chiggers and any single weather factor, but the chigger population seemed to be adversely affected by a 2 month period during which total evaporation greatly exceeded total rainfall. Direct fluorescent antibody examination of tissues from unfed L. (L.) deliense showed that 2 of 420 larvae (0.5%) contained organisms morphologically resembling R. tsutsugamushi. Considering the vector load and numbers of chiggers being returned to the ground by a given host, a rate of 0.5% appeared adequate to account for the prevalence rate of R. tsutsugamushi observed in the 2 host species.
Leptotrombidium (Leptotrombidium) arenicola Traub, a vector of scrub typhus, had previously been found to occur in the coastal vegetation behind the edge of open sand along the beaches of Peninsular Malaysia. Surveys of the west coast beaches of Sabah and Sarawak were conducted to determine if this species occurs in similar habitat in East Malaysia on the island of Borneo. Leptotrombidium (L.) arenicola was not collected from the eighteen sites studied. Of the 11,982 mite larvae collected, 55 per cent were L.(L.) deliense (Walch), a well-known, widespread vector of scrub typhus.
Clinacanthus nutans Burm, a herb reputed in Thailand and Malaysia to be "snakebite antidote" has been tested in vitro and in vivo for antivenin activity. The aqueous extract of C. nutans leaves has been found to have no effect on the inhibition of neuromuscular transmission produced by purified Naja naja siamensis neurotoxin in isolated rat phrenic-nerve diaphragm preparations. The extract of C. nutans, when given orally or intraperitoneally, are ineffective in prolonging the survival time of experimental mice receiving lethal doses of N.n. siamensis crude venom. Oral administrations of the herb extracts pretreated with alpha-amylase or beta-amylase also fail to protect the animal. It is concluded that the extract of C. nutans can not antagonize the action of cobra venom.
A case of urogenital myiasis caused by Chrysomya bezziana (Diptera: Calliphoridae) was diagnosed in a 76-year old patient who had carcinoma of the rectum. A total of 35 larvae were obtained from ulcers near the external genitalia and urethra opening. Larvae pupated within 1 to 2 days and 6 days later emerged as adult males. These were identified as Chrysomya bezziana. Female flies possibly attracted by the fetid odour, laid eggs in the existing lesions in the urogenital area, the larvae invading and feeding on living tissue. Lack of personal hygiene was the contributing factor for the cause of urogenital myiasis in this patient.
Serum ferritin and haemoglobin estimates were carried out on 78 first time blood donors with a view to determining iron store status. Of these 30 were Malays, 20 were Chinese and 28 were Indians. The ferritin level in Malay donors ranged from 16-160 mg/ml (mean 83 +/- 49.4 mg/ml in chinese donors is ranged from 36-500 mg/ml (mean 242.8 +/- 132 mg/ml), and in the Indian donors it ranged from 5 - 270 mg/ml (mean 94.6 +/- 67.9 mg/ml). The haemoglobin concentration for the whole group was 14.9 +/- 1.49 g/dl. There was no correlation of haemoglobin concentration with serum ferritin levels.
A serum survey of several characteristic groups of humans in urban, rural, and forested areas of Peninsular Malaysia for evidence of infection with three alphaviruses (Sindbis, getah, and chikungunya) was made on 4384 specimens collected between 1965 and 1969. Analysis of the serological results indicated that 1) persons residing in predominantly rural and forested areas have higher frequencies of specific alphavirus antibody of all three viruses than persons residing in urban areas, 2) human infection with chikungunya virus appears to be at a low level of activity but is widespread, although more common and recent in the northern part of the country, and 3) Sindbis and getah viruses probably do not represent a threat to the public health, but chikungunya virus remains a potential menance and may be responsible for future epidemics transmitted by A. aegypti and A. albopictus mosquitoes.
Non-haemoglobin liver iron was estimated in 275 presumably normal individuals from Kuala Lumpur and Singapore at necropsy. Liver Iron concentrations were highest during the first two years after birth but declined sharply during childhood. They then rose gradually and reached a value of 20 mg/100gm in adult males. Liver iron concentrations of childbearing women remained low and it was only after menopause that values in women rose to those of males. Liver iron stores increased with age to a plateau of about 300 mg in adults, suggesting that this value may represent the adult size for liver iron store. Among the three major ethnic groups in Malaysia and Singapore, Chinese, being in a better socio-eonomic class, had larger liver iron stores. The median liver iron concentrations of Malaysians and Singaporeans, on the whole, were lower than those reported from western populations and as many as 35 per cent of the women were in a subclinical state of iron deficiency.
A total of 736 sera collected from cord blood babies, children and adults of both sexes and of different age groups in Malaysia were tested using indirect fluorescent antibody technique for Toxoplasma antibodies. The RH strain of Toxoplasma gondii zoites were used as antigen. One hundred and twenty five sera which were reactive at 1:64 or high titres were tested with IgM specific conjugate. Results of the present studies showed that the prevalence of Toxoplasma antibody was highest among the Malays and lowest among children than among adults. The significance of Toxoplasma specific IgM was discussed.