Hepatitis A virus: declining seroprevalence in children and adolescents in Southeast Asia.

The prevalence of hepatitis A virus (HAV) in a country largely reflects its standards of hygiene and socioeconomic conditions. Countries which undergo socioeconomic development show major change in HAV prevalence from high to low endemicity, and this is largely reflected in patterns of age-related seroprevalence. This paper presents age-related HAV seroprevalence patterns of SE Asian countries, and highlights how these patterns have changed over recent decades. Singapore, Thailand and Malaysia have experienced a decline in childhood and adolescent HAV seroprevalence, typical of countries which undergo socioeconomic development. By contrast, India has remained a country of high endemicity, with almost universal seroconversion in childhood. The Philippines and Vietnam show age-related seroprevalence patterns typical of high to moderate endemicity, while Indonesia shows significant regional variation in HAV seroprevalence. Populations within countries which exhibit major improvements in endemicity and age related HAV seroprevalence patterns are at risk of HAV epidemics, and a paradoxical increase in incidence tends to occur as seroconversion shifts from children to adults. The residents of these countries, a significant number of whom are at-risk, would benefit from a program of vaccination, as would non-infected individuals visiting high-risk areas.

[The clinical efficacy of and tolerance for lariam (mefloquine) in tropical malaria in the south of the Socialist Republic of Vietnam]. / Klinicheskaia éffektivnost' i perenosimost' lariama (meflokhina) pri tropicheskoi maliarii na iuge SRV.

The study was performed in the area of distribution of tropical malaria resistant to 4-aminoquinolines (Vietnam) on 30 patients receiving lariam (mefloquine). The results were compared to the standard therapy with quinine and fansidar. They indicate a high efficacy of and a good tolerance to the drug tested. The use of lariam leads to a more rapid (as compared to the standard treatment) elimination of parasitemia and complete eradication of the disease relapses. The findings make it possible to recommend lariam for the prevention and treatment of tropical malaria.

Evaluation of new antiviral agents: II. The use of animal models.

Antiviral chemotherapy has become a reality in the 1980s. Since the use of animal models in the testing of new antiviral agents is an inevitable step prior to clinical trial in human patients, it is important to understand the basic principles of using model systems. Briefly reviewed in this paper are the heterologous and homologous animal models which have been used for studies of various herpesvirus infections in humans. Discussions of the use of the guinea pig models mainly, for members of the Herpesviridae are presented in more detail. Precautions needed for the development of new animal models, and suggestions proposed for the use of animal models for testing new antiviral agents are outlined. It is hoped that new animal models will be developed in the foreseeable future for evaluating the much needed effective but less toxic antiviral agents for a variety of human viral diseases.

Occurrence of infection with group B coxsackievirus in rheumatic and nonrheumatic Filipino children.

The pathogenesis of rheumatic fever has been linked to various immune mechanisms involving streptococcal antibodies and heart tissue antigens. Latent myocarditis due to group B coxsackievirus has also been considered as a possible conditioning factor. The validity of the role of infection with group B coxsackievirus in rheumatic fever was tested by determining the incidence of type-specific neutralizing antibodies in sera of Filipino children. Analysis of the results by means of a normal Z-test showed that the incidence in rheumatic children was not statistically significant in comparison to the incidence in asymptomatic children.

Uncoating of poliovirus by isolated plasma membranes.

Poliovirus type I LSc strain labeled with (14)C-uridine was adsorbed onto isolated plasma membranes and incubated with them. When membranes from Hep-2 or Vero cells were used, 22% of the label was converted to a trichloroacetic acid-soluble form, when trypsin or ribonuclease was added, the fraction rendered soluble was increased, and when the two enzymes were added in sequence, 85% or more of the label became trichloroacetic acid-soluble. This labilization of poliovirus could be reproduced when butanol-solubilized proteins from membranes were substituted for the whole plasma membranes, but it did not occur with membranes from polio-virus-resistant calf kidney or BHK-21 cells.