Hepatitis B virus seroprevalence and risk assessment among personnel of a governmental hospital in Bangkok.

At present, the risk for acquiring hepatitis B virus (HBV) among hospital personnel is high. A cross-sectional analytic study of 380 hospital personnel was conducted in a governmental hospital in Bangkok to investigate HBV sero-prevalence and to assess risk factors in order to develop the risk assessment form for screening the occupational risk of HBV among this group. The studied personnel who had no histories of HBV vaccination and jaundice before working in the hospital were included by voluntary participation. All studied personnel were interviewed by using a structured questionnaire consisted of risk exposure factors and some medical histories. Blood specimens were collected for determining HBV sero-markers (HBsAg, Anti-HBs, and Anti-HBc) by an enzyme immunoassay. The risk factors were analyzed by using Odds ratio (OR), chi2-test, and multiple logistic regression. The results revealed that 48.68% were positive for any HBV markers. The HBsAg positive rate was 3.42%, anti-HBs +/- anti-HBc was 43.16 and 2.11% were positive only anti-HBc. The significant risk factors from univariate analysis were: age over 30 years (OR=3.15, p<0.0001), marital status (OR=2.19, p=0.0002), working in risk ward (OR=2.89, p=0.0274), duration of working over 5 years, (OR=2.81, p<0.0001), a history of accident from working (OR=1.58, p=0.0354), and a history of needle stick (OR=1.83, p=0.0064). After multivariate analysis, the significant risk factors included age over 30 years (OR=2.99, p<0.0001), sex: male (OR=3.05, p=0.0020), working in risk ward (OR=2.81, p=0.0337), and a history of needle stick (OR=2.16, p=0.0030). The risk assessment form was developed by using risk scores. The validity was calculated by the Receiving Operating Curve. The sensitivity of this form was approximately 50% and the specificity was 80% when the cut-off score at risk > or = 5 was used.

Compliance with the law on car seat-belt use in four cities of Thailand.

Surveys to determine the scope of compliance with the law requiring seat-belt use in Thailand were conducted by observation and interviews with drivers in four cities: namely, Bangkok Metropolis, Chiang Mai, Phuket and Nakhon Ratchasima. The work was carried out in two separate sessions: during the first month following enactment of the law, and six months after its enactment. The sample comprised 46,949 vehicles in the first session (January 1996) and 76,188 vehicles in the second session (July 1996). The results showed that 42.7 per cent of drivers used seat-belts in January and 30.7 per cent in July. When the data were disaggregated according to cities, it was found that more Bangkok drivers complied with the seat-belt law than in Phuket, 24.6 per cent; Chiang Mai, 22.1 per cent; and Nakhon Ratchasima, 18.3 per cent relatively low compliance rate was encountered among drivers of pick-up trucks (including those with modified roofs) and vans, particularly farmers and the self-employed. Women drivers tended to abide by the law more often than men (OR = 1.7, 95% CI = 1.12, 1.23). Inter-city travelers wore seat-belts more than those traveling in the city (OR = 1.74, 95% CI = 1.68, 1.80). About one-fifth of non-users or those who rarely used seat-belts were unsure of the effectiveness of seat-belts in preventing serious injury or death in the case of an accident. Discomfort associated with using seat-belts and the perception that they were rendered unnecessary because of slow traffic in cities were other reasons for non-compliance in 50.6 per cent and 43.9 per cent of cases, respectively. The decline in compliance with the law six months after its enactment indicates that there may be a problem with uniform and consistent enforcement of the law.

Seroprevalence of scrub typhus infection in patients with pyrexia at some malaria clinics in three western provinces of Thailand.

In Thailand, the epidemiological data on scrub typhus infection represents only "the tip of an iceberg" especially in malaria clinics where patients come to seek attention because of other febrile illnesses that may have initial clinical signs that are indistinguishable from malaria. The objectives of this study were to determine the prevalence of antibody titers to Orientia tsutsugamushi, and its various strains, among patients at some malaria clinics in three western provinces of Thailand. The sample was represented by 200 patients from 6 malaria clinics in Ratchaburi, Petchaburi and Kanchanaburi provinces between June and November, 1994. Blood specimens were collected with their consent. Immunofluorescent antibody assays (IFA) were used for measuring IgM and IgG antibody titers for scrub typhus infection. The results showed that the prevalence rate for scrub typhus infection (IgM and/or IgG titer > or = 50) was 59.50% (119 cases). The immunofluorescent antibody response to various strains of O. tsutsugamushi showed that co-infections with the Karp, the Gilliam and the Kato strains were the most common (found in 68.10% of cases). Geometric mean antibody titers (GMT) were highest for the Karp strain, followed by the Gilliam then Kato strains. In conclusion, this study indicates that the prevalence rate of scrub typhus is not rare in these areas.

Comparison of dengue virus antigens in sera and peripheral blood mononuclear cells from dengue infected patients.

The presence of dengue virus antigens in acute sera and peripheral blood mononuclear cells (PBMC) from dengue infected patients were determined by a biotin-streptavidin enzyme-linked immunosorbent assay (BS-ELISA). The frequency of the antigens detected in PBMC was higher than that in sera (53.8% vs 18.9%). In comparison with sera, the detection rate in PBMC was greater than six times: 7 cases were positive only in sera whereas 44 cases were positive only in PBMC, p < 0.001. The presence of the antigens in the sera did not depend on the severity of the disease, i.e. dengue fever, dengue hemorrhagic fever (grades I and II) or dengue shock syndrome (grades III and IV). In contrast, the presence of the antigens in PBMC increased from 36.8% to 100% when the infection was more severe. The dengue virus antigens could be detected in the samples collected between day 2 and day 7 after onset of the disease with the highest rate of detection (68.8%) in PBMC collected on day 4. The data suggest the use of PBMC with access to the appropriate acute-phase specimen for detection of dengue virus antigens.