Reactogenicity and immunogenicity of a varicella vaccine in healthy seronegative and seropositive subjects.

The epidemiology of varicella appears to be changing: an unexplained upward age shift in varicella prevalence and a subsequent dramatic rise in morbidity and mortality among adolescents and adults have highlighted the importance of effective varicella mass vaccination programs. This age shift is being seen in temperate regions but is particularly marked in tropical and sub-tropical regions. To assess the need for serological pre-screening in mass vaccination programs, we performed an open study to compare the reactogenicity and immunogenicity of a varicella vaccine in initially seronegative and seropositive subjects to see whether there was an increase in reactogenicity among initially seropositive subjects. Two hundred and forty-six seronegative and seropositive male and female subjects, aged 9 months to 60 years, received a single dose of a live attenuated varicella virus (Oka-strain) vaccine, Varilrix (GlaxoSmithKline Biologicals, Rixensart, Belgium). Subjects were categorized according to antibody status and age group; serum antibodies were measured before and after vaccination (day 42). The study showed that there was no difference in reactogenicity in initially seropositive vaccinees compared with initially seronegative subjects. The varicella vaccine was found to be safe and well tolerated in all age groups. Ninety-eight percent of initially seropositive and 94.8% of initially seronegative subjects reported no clinical signs or symptoms during the 42-day follow-up period. The vaccine was immunogenic in both groups. The seroconversion rate after 6 weeks in initially seronegative subjects was 94.3%. In 53.0% of initially seropositive subjects of all age classes, a 4-fold rise in antibody titer was observed.

Prevalence of antibodies to Toxoplasma gondii among urban and rural residents in the Philippines.

A survey of antibodies to Toxoplasma gondii was carried out among residents in urban (Metro Manila) and rural (Mindoro and Leyte) areas in the Philippines. A total of 1,173 serum samples were examined for Toxoplasma antibody by an ELISA method. The overall seropositivity was 11.1% (n=904, 12.4% in males, 10.0% in females) in Metro Manila, 61.2% (n=152, 63.3% in males, 53.1% in females) in Mindoro, and 30.1% (n=113, 34.3% in males, 22.5% in females) in Leyte, indicating significantly higher (p<0.001) seropositivities in rural than urban settings. No significant differences in seropositivities were observed between males and females. In each group, seropositivity tended to increase with age of the subjects.

Differential distribution of hepatitis C virus subtypes in Asia: comparative study among Thailand, Indonesia, the Philippines and Japan.

Hepatitis C virus (HCV) is currently classified into at least six major genotypes, each of which is further divided into a number of subtypes. It has been reported that prevalence of each subtype varies among different geographical regions of the world and that severity of liver disease and sensitivity to interferon treatment varies with different subtypes. The purpose of this study was to determine and compare the prevalence of each subtype among HCV isolates in different areas in Asia such as southern (Hat Yai) and northern (Chiang Mai) parts of Thailand, Indonesia (Surabaya), the Philippines (Manila) and Japan (Kobe). Sera were obtained from various groups of patients and tested for antibodies against HCV using second and/or third generation ELISA kits. RNA was extracted from anti-HCV-positive sera and reverse-transcribed into cDNA. The cDNA-preparations were subjected to nested PCR to amplify NS5B and 5'-untranslated region (5'UTR) sequences. Amplified fragments were sequenced and subtypes of the isolates were determined based on sequence similarities with reported sequences. In Chiang Mai and Hat Yai, Thailand, HCV-3a, HCV-1a and HCV-1b were common in various populations. HCV type 6 variants were commonly found among blood donors and drug addicts in Chiang Mai, but not in Hat Yai. In Surabaya, Indonesia, HCV-2a was frequently detected in blood donors, but less frequently in patients with chronic liver disease. In blood donors, HCV-1a, HCV-1b and HCV-1d were more strongly associated with elevation of serum aminotransferase levels than HCV-2a. HCV-1a was significantly more common in patients on maintenance hemodialysis than in blood donors or patients with chronic liver disease. HCV-1d was detected exclusively in Indonesia. Another unique subtype HCV-3g was found also in Indonesia, though less frequently than HCV-1d. In the Philippines, a vast majority of the isolates were either HCV-1a or HCV-1b. Thus, HCV subtype prevalence varies among different regions of Asia.

A review of Japanese encephalitis cases in the Philippines (1972-1985).

Few studies have shown that JE does occur in the Philippines with the majority of the cases affecting the 1-10 year age group in places where rice fields abound. The morbidity rate is 15-17%, with a mortality rate of about 7-30%.