Parasitic infections among Orang Asli (aborigine) in the Cameron Highlands, Malaysia.

In April 2004, an outbreak of acute diarrheal illness occurred among the Orang Asli (aborigine) in the Cameron Highlands, Pahang State, Peninsular Malaysia, where rotavirus was later implicated as the cause. In the course of the epidemic investigation, stool samples were collected and examined for infectious agents including parasites. Soil transmitted helminthes (STH), namely Ascaris lumbricoides (25.7%), Trichuris trichiura (31.1%) and hookworm (8.1%), and intestinal protozoa, which included Giardia lamblia (17.6%), Entamoeba histolytica/E. dispar (9.4%), Blastocystis hominis (8.1%) and Cryptosporidium parvum (2.7%), were detected. Forty-four (59.5%) were infected with at least one parasite, 24 (32.4%), 12 (16.2%) and 8 (10.8%) had single, double and triple parasitic infections, respectively. STH were prevalent with infections occurring as early as in infancy. Giardia lamblia, though the most commonly found parasite in samples from symptomatic subjects, was within the normally reported rate of giardiasis among the various communities in Malaysia, and was an unlikely cause of the outbreak. However, heavy pre-existing parasitic infections could have contributed to the severity of the rotavirus diarrheal outbreak.

Assessment of Nipah virus transmission among pork sellers in Seremban, Malaysia.

Between September 1998 and May 1999, 265 cases of encephalitis were reported from among those involved in pig rearing. A few cases were also reported among abattoir workers. This raised questions of the risk of transmission among those who handled raw pork. A serosurvey was conducted among pork sellers in Seremban town, which is about 20 km from one of the pig rearing areas which had reported cases of encephalitis. It was found that out of the 28 pork sellers tested, only one tested positive for Nipah virus antibodies and that this pork seller also worked in an abattoir in the same district, removing the urinary bladders from slaughtered pigs. Based on these findings, it was concluded that the risk of transmission of the virus from handling raw pork appeared to be low.

Risk factors for Nipah virus transmission, Port Dickson, Negeri Sembilan, Malaysia: results from a hospital-based case-control study.

A hospital-based case-control study of viral encephalitis was carried out at Port Dickson Hospital, in the state of Negeri Sembilan, Malaysia. Between March and May 1999, 69 clinically diagnosed viral encephalitis cases and 31 controls were interviewed. Job histories on pig farming activities were assessed by a group of epidemiologists and veterinary surgeons. Results show that among clinical cases of viral encephalitis, 52 (75.4%) cases were diagnosed to have Nipah virus infection based on positive serology for antibodies to the cross-reacting Hendra virus antigen. The Nipah virus encephalitis was significantly associated with a history of working in pig farms (p < 0.001, OR = 196.0, 95% CI = 20.4-4741.6), history of contact with animals (p < 0.001, OR = 38.3, 95% CI = 8.2-209.0) and with history of direct contact with pigs (p = 0.002, OR = 34.4, 95% CI = 2.6-1,024.4). The Nipah virus infection was also significantly associated with history of feeding/cleaning pigs (p < 0.001, OR = 102, 95% CI = 11.9-2,271.5). These results provide evidence that involvement in pig farming activities is significantly associated with the risk of getting Nipah virus infection. They are potential risk factors for Nipah virus transmission in the major pig-producing area of Bukit Pelandok, Port Dickson Negeri Sembilan.

Poliomyelitis and measles serosurvey in northern Malaysia.

In 1990 the Institute for Medical Research carried out a serosurvey in the state of Kelantan to study the age stratified immune prevalence rates for measles and poliomyelitis. Our findings indicate that 981 out of 1,097 (89%) of the population screened had measles antibodies and more than 90% (366 out of 400) had antibodies to all three serotypes of poliovirus. The susceptible group for measles was infants below one year of age, of whom 53.3% (8/15) did not have measles antibody. Of 400 subjects, 125 (31.3%) who were either incompletely vaccinated or had not been vaccinated against poliomyelitis, had polio neutralizing antibodies to all three poliovirus serotypes, suggesting herd immunity in the population. No high risk age group could be identified for poliomyelitis.