GB virus C or hepatitis G virus (GBV-C/HGV), a novel Flavivirus, is detected in 1.5% of US blood donors. The prevalence is higher in multiply transfused patients and in persons with liver disease. Because of the increased incidence of hepatitis in Asia, sera from healthy Vietnamese were tested for the presence of GBV-C/HGV RNA by the reverse transcription polymerase chain reaction. Viral RNA was detected in 5.7% of those tested; 6 of 81 volunteer blood donors had positive samples as did 5 of 97 army recruits and 2 of 50 postpartum women. When the 188-bp product from 6 subjects was sequenced, there was 75%-85% homology at the nucleotide level compared with published sequences, indicating a high degree of genotypic variation, even within a putatively well-conserved region of the viral genome. Viremia with this non-cell-associated novel virus appears to be common among normal persons in Vietnam.
Little is known about the influence of environmental and ethnic factors on the epidemiology of immune thrombocytopenic purpura (ITP). Therefore we compared the initial presentation and condition after 6 mo in 90 Vietnamese and 89 German and Swiss children with newly diagnosed ITP. Data from the two cohorts were collected within the same time period. No differences in age and sex were observed between the Asian and European cohorts, but significant differences between initial platelet count, the occurrence of dry versus wet bleeding symptoms, and infection preceding the onset of ITP were found. Children who had chronic ITP also differed with respect to platelet count and postinfectious state, but not initial bleeding type. In addition, chronic ITP occurred more often than expected with a male to female ratio of 1.2 in Vietnam and 2 in Germany and Switzerland. The data support the potential influence of environmental or ethnic factors on the different aspects of ITP, and point to the need for further epidemiologic investigations.
In Vietnam, the carrier rate for -thalassemia varies from 1.5% to 25% depending on the ethnic groups of the population. The molecular basis of -thalassemia in South Vietnam was studied in 50 unrelated -thalassemia patients. Of these, 31 had -thalassemia/Hb E, 18 were homozygous for -thalassemia, and 1 carried the -thalassemia trait. The majority of the patients were Kinh, four were Chinese, and two were Kinh-Chinese. All had severe anemia and received blood transfusions regularly, every 1-3 months. Hepatosplenomegaly was found in all patients, and splenectomy had been done in six patients. Normal ␣-globin genotype (␣␣/␣␣) was found in all subjects. Reverse dot-blot hybridization using oligonucleotide probes specific for Southeast Asian mutations can detect -thalassemia in 60 chromosomes in addition to 31 chromosomes with  E mutation.
In countries where malaria is endemic, its transmission is a hazard of blood transfusion. The microscopical and immunological methods in current use for malaria diagnosis are unsatisfactory for low levels of parasitaemia in blood donations. The polymerase chain reaction (PCR) can be 100-fold more sensitive than thick blood film examination when appropriate primers are used and can detect and distinguish Plasmodium falciparum and P. vivax in a single tube. A study of 1506 blood donations in Ho Chi Minh City (3 of which were positive) suggests that PCR can provide an effective screen for P. falciparum under local conditions. Studies in a region of Viet Nam where malaria is common showed that PCR detects many more cases of low-level parasitaemia (19/30) than thick blood films (4/30).
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