Nipah virus is a highly pathogenic but poorly known paramyxovirus from South and Southeast Asia. In spite of the risks that it poses to human health, the geography and ecology of its occurrence remain little understood-the virus is basically known from Bangladesh and peninsular Malaysia, and little in between. In this contribution, I use documented occurrences of the virus to develop ecological niche-based maps summarizing its likely broader occurrence-although rangewide maps could not be developed that had significant predictive abilities, reflecting minimal sample sizes available, maps within Bangladesh were quite successful in identifying areas in which the virus is predictably present and likely transmitted.
From October 13 to October 21, 1999, a total of 46 males, aged 8 to 19 years, were admitted to Beaufort Hospital after swimming in the creek near an oil palm plantation in Kampung (Kg) Kebatu, Beaufort. Thirty (30) presented with symptoms including fever, vomiting, bodyache, giddiness, headache, chest pain and cough, while 16 others, were asymptomatic. One, a 15 year old boy, died from haemorrhagic shock secondary to pulmonary haemorrhage. The onset of the illness was from 11 October to 19 October 1999. A case-control study found that the outbreak was associated with swimming in the creek (p<0.0001). A total of 44 paired sera samples were sent for microscopic agglutination test (MAT), 5 pairs showed sero-conversion, 3 pairs had 4 fold rise in titre and 18 pairs were positive at >320. The findings indicated that Leptospirosis was the cause of the outbreak of this illness and the contaminated creek water was the source of the infection. The occurrence of flooding and stagnation in the creek following the heavy rainfall during the first week of October 1999 could have contributed to the timing of the outbreak.
Plasmodium knowlesi a simian malaria parasite is currently affecting humans in Southeast Asia. Malaysia has reported the most number of cases and P. knowlesi is the predominant species occurring in humans. The vectors of P. knowlesi belong to the Leucosphyrus group of Anopheles mosquitoes. These are generally described as forest-dwelling mosquitoes. With deforestation and changes in land-use, some species have become predominant in farms and villages. However, knowledge on the distribution of these vectors in the country is sparse. From a public health point of view it is important to know the vectors, so that risk factors towards knowlesi malaria can be identified and control measures instituted where possible. Here, we review what is known about the knowlesi malaria vectors and ascertain the gaps in knowledge, so that future studies could concentrate on this paucity of data in-order to address this zoonotic problem.
Charles Wilberforce Daniels was a major pioneer in the early days of the newly-formed medical specialism--tropical medicine. At the London School of Tropical Medicine (LSTM) of which he was a leading stalwart, he took an active part in research, teaching and administration. But like others in the new discipline he spent a great deal of time at various tropical locations: Fiji, British Guiana--where he made important observations on various forms of filariasis-- east Africa, and Malaya. However, his most important research contribution was arguably confirmation of Ronald Ross' 1898 discovery of the complete life-cycle of avian malaria, in Calcutta.
A study of the prevalence and intensity of soil-transmitted helminthiasis among pre-school children aged 0 to 7 years from an Orang Asli village resettlement scheme in Gua Musang, Kelantan was undertaken. The overall prevalence of soil transmitted helminthic (STH) infections was 56.0%. The predominant helminth found was Ascaris lumbricoides while the commonest type of infection was a mixed infection with Ascaris lumbricoides and Trichuris trichiura. The prevalence rates of Ascaris, Trichuris and hookworm infections were 47.5%, 33.9% and 6.2% respectively. The intensity of Ascaris infections were 64.5% light, 27.3% moderate and 8.3% heavy whilst the intensity of Trichuris infections were 80.5% light, 18.3% moderate and 1.2% heavy. However, the intensity of hookworm infections were 86.7% light, 13.3% moderate and no heavy infection. The prevalence of helminthiasis (STH) shows an-age dependent relationship, with the lowest prevalence in 0-< 1 year age group and highest in the 6-< 7 year age group.
Nosocomial infections are posing an increasingly serious problem in the hospital setting. With the increasing use of ultrasound in medical diagnosis, there is the potential for transmission of nosocomial infections via the ultrasound transducer and coupling gel. We evaluated the use of different membranes (three types of commercially available household cling film, condom, surgical glove and Opsite) applied over the ultrasound probe to determine if these were safe, convenient, cost-effective and did not impair the performance parameters of the ultrasound probe. None of the membranes impaired the physical scanning parameters using a Multi-Purpose Tissue/Cyst Phantom. The cling film was ideal for general use in terms of cost and convenience as well as safety. For sterile use the Opsite was better overall compared to the surgical glove, though it costs significantly more. The condom and surgical glove, though safe, were not very convenient to use for scanning.
Surveys were conducted of adult and immature mosquitoes in an area undergoing oil palm development in north Sarawak. Point prevalence data from 2 sites were collected annually, coinciding with annual phases of forest clearing, burning/cultivation, and maintenance. Major habitat perturbation during the forest/clearing transition shifted the major mosquito faunal equilibrium in terms of species composition, relative density and occurrence. Analyses of variance showed that the mean numbers of 4 species of Anopheles decreased significantly after forest clearing. Relative densities of immature stages decreased after forest clearing, but A. letifer and Culex tritaeniorhynchus remained relatively unchanged after the second year. Comparisons with the pre-development forest stage showed that the reductions in person-biting rates, adult survival and combined entomological inoculation rates (EIR) of A. donaldi and A. letifer decreased the risk of malaria transmission by 90% over the 4 years period. Concomitant reductions in EIR and annual malaria incidence were also correlated. This study highlighted the 'law of unintended consequences', since 2 contrasting effects were observed: reduction of malaria vectors but concomitant increase of dengue vectors.
Infection is an important cause of morbidity and mortality in immunocompromised patients. The high risk of infection is not only the consequence of the underlying disease but also the result of the diagnostic, monitoring and therapeutic procedures performed on these patients. Infections may be exogenous or endogenous in origin. The prevention of exogenous infections requires a high standard of hygiene. As many infections are acquired in hospitals, an effective control of nosocomial infection programme is crucial in preventing infections in the immunocompromised. Prevention of endogenous infections involves suppression of the aerobic bacterial flora (selective decontamination) and measures to maintain gastrointestinal epithelial integrity to reduce risk of translocation of intestinal flora. Boosting the host immunity through passive and active immunisation should also be considered. Prevention of infection in the immunocompromised is no easy task and requires a multidisciplinary approach.
Factors affecting the mechanical transmission of rotavirus by the legs and wings of the housefly, Musca domestica L., were examined in a laboratory study. Rotavirus was picked up when houseflies walked on thin smears of clarified rotavirus suspensions. The addition of glycerol, which increased viscosity of the virus suspension, and particulate human feces slightly increased the proportion of flies contaminated with virus. However, the addition of glycerol greatly reduced the average number of virus particles picked up per fly, whereas feces greatly increased the number of particles. The proportion of flies with virus-contaminated legs, which transferred virus to > 1 contact surface, was increased by longer contact time with the surface and when the contact surface was agar instead of glass. Most virus particles were deposited on 1st contact with the surface. Most flies dislodged virus particles inoculated on the underside of their wings soon after the start of simulated flight. Our data indicated that the nature of the virus-suspending medium has a greater effect on the level of virus contamination than on the ability to become contaminated. The importance of walking as a mode of virus transport depends on the nature of the contact surface, the risk of the contaminated fly settling first on a surface likely to come into contact with humans, and fly numbers.
The shedding pattern of the protozoan parasite, Blastocystis hominis, is investigated in man and in experimental animal infections. The shedding pattern of the vacuolar and cystic forms of Blastocystis hominis in infected individuals have been shown in the present study to be irregular. The study shows that there is marked fluctuation in the shedding of the parasite from day to day, varying from as high as 17 to 0 per x40 microscopic field. The cystic stages when estimated in 8 Blastocystis-infected individuals ranged from as high as 7.4x10(5) cysts per gram of stool to 0. The shedding of cystic and vacuolar forms observed over a period of 20 days in experimentally-infected Wistar rats were not only shown to be irregular but the amount varied from host to host. The study has important diagnostic implications in that the stool samples must be collected more than once from patients showing clinical signs and symptoms to eliminate the cause of it to Blastocystis. The study also shows that there are asymptomatic individuals who pass a large amount of cysts as such individuals should be treated to prevent transmission to others.
North American strains of Aedes albopictus, an Asian mosquito recently introduced into the Western Hemisphere, exhibit photoperiodic sensitivity and cold-hardiness characteristics similar to strains originating from temperate zone Asia. Trade statistics for used tire imports, the most likely mode of introduction, also indicate a north Asian origin. Aedes albopictus, an important vector of dengue and a potential vector of many other arboviral diseases, may therefore have the capability of infesting much of temperate North America.
A survey of a total of 1,157 Indian primary school children from eight schools from urban and rural areas in and around Kuala Lumpur showed an overall
prevalence of infection with soil-transmitted helminthiasis of 89.02%. The prevalence and intensity of infection were consistently high among both school boys and girls throughout the six years of primary school. The predominant helminth was Trichuris trichiura - both as single and mixed infections. The commonest type of helminthic infection among urban primary school children was mixed infections with Trichuris trichiura and Ascaris lumbricoides. Hookworm infections, both as single or mixed infections, were more common among school children from rubber and oil palm estates in the rural areas.
Surveillance methods for Coquillettidia crassipes were studied in an open housing estate near Kuala Lumpur using three types of traps Trinidad 10 trap, modified Lard can trap and IMR trap, each baited with chicken or pigeon. All traps attracted Cq. crassipes. There was no significant difference in the catches in the three traps. There was also no significant difference between chicken and pigeon as bait. Catches at heights of 1.5, 3, 4.5 and 6 m did not show any significant difference in density. Cq. crassipes was active at night with an early peak during the first hour of the night and a minor peak between 0100 and 0200 hours. The activity of the parous and nulliparous sections of the population was similar, except that a higher proportion of the parous females was active during the second peak compared with the nulliparous females. The parous rate was 22.3%, and the probability of survival through one day for two gonotrophic cycles was 0.711 and 0.650. The infection rate for Cardiofilaria was 29 out of 1052 (2.76%) and the infective rate (L3 larvae) was 13 out of 1052 (1.24%). 48.3% of the infected Cq. crassipes had a worm burden of more than ten larvae. One of the chickens in the traps was positive for microfilariae of Cardiofilaria four weeks after exposure as bait. Laboratory bred Cq. crassipes fed on this chicken produced infective larvae in ten days, and these were inoculated into clean chickens and pigeons. Microfilariae appeared in the chickens but not in pigeons. The adult worms recovered await identification.
In this retrospective review of 16 children with vulvovaginitis due to Neisseria gonorrhoeae, the authors attempt to estimate the incidence of this infection and to ascertain the routes of transmission. From January 1977 to December 1982, 422 cases of gonococcal vulvovaginitis in women of all age groups were encountered at the University Hospital, Kuala Lumpur, Malaysia. Of these, 406 cases (96.2%) occurred in adults, and 16 cases (3.8%) occurred in children younger than 12 years of age. Penicillinase-producing N. gonorrhoeae (PPNG) strains were isolated from five (31%) of the 16 girls; all five cases were subsequently treated with cefuroxime and probenecid. The rest responded to intramuscular procaine penicillin. Although all patients appeared to be cured, only ten of 11 (two with PPNG) had test-of-cure cultures performed after treatment. Although interviewing the parents revealed no history of sexual contact in these children, nine of the girls were linked to culture-positive adult(s).
In the outbreak of cholera in Perak in 1978, a study on 179 cholera patients (cases) from 8 health districts in the state indicated that those afflicted with the disease were from the rural areas, belonged to the lower socio-economic class and had little or no formal education. Under such conditions, it is expected that personal hygiene may not be satisfactory and person to person contact could play an important role in the transmission of the disease especially among those living in close contact. 34.2 percent of the 164 households of the cholera patients contained injected household contacts. From 1 to 6 infected household contacts per household were found for household size ranging from 2 to 18. Ninetyjive (8.6 percent) of the total 1101 household contacts were injected. Only 8 of these 95 infected household contacts developed clinical symptoms giving a ratio of 1:12 symptomatic to inapparent injections. While most of the contacts probably acquired their infection from the patient who constitutes the index case, the role of the asymptomatic carrier in the transmission ofinjection cannot be underestimated.