We determined the nucleotide sequences of the whole structural protein gene of four new dengue-2 viruses by the primer extension dideoxy chain termination method, using multiple cDNA clones for six overlapping gene regions. The nucleotide sequences of the major non-structural protein NS1 gene of these viruses were also determined by direct sequencing of the reverse-transcription polymerase chain reaction products. These viruses were isolated from dengue patients with different clinical severities in Nakhon Phanom, Northeastern Thailand in 1993. The results were compared with the sequences of prototype New Guinea C strain and other reference strains. All four viruses revealed highest homology to New Guinea C strain. The homology between each of the four strains and New Guinea C strain varies from 95.09% to 95.29% in its nucleotide sequences, and from 97.24% to 97.78% in its amino acid sequences covering all structural proteins and NS1 protein. The PreM region shows the highest divergence (6.59% to 7.32%) in its nucleotide sequence, whereas C protein is most highly conserved (only 1.75% to 2.63% divergence). Our data showed that there are certain molecular differences in the genomic structure of these four new isolates, which indicate the possibility that these changes are related with the virulence of the virus strains.

Objective Rubella vaccine is not included in the immunization schedule in Myanmar. Although surveillance for outbreaks of measles and rubella is conducted nationwide, there is no routine surveillance for congenital rubella syndrome (CRS). Therefore, we organized a study to assess the burden of CRS. Methods From 1 December 2000 to 31 December 2002 active surveillance for CRS was conducted among children aged 0-17 months at 13 hospitals and 2 private clinics in Yangon, the capital city. Children with suspected CRS had a standard examination and a blood sample was obtained. All serum samples were tested for rubella-specific IgM; selected samples were tested for rubellaspecific IgG and for rubella RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Findings A total of 81 children aged 0-17 months were suspected of having CRS. Of these, 18 children had laboratory-confirmed CRS (7 were IgM positive; 7 were RT-PCR positive; and 10 were IgG positive at > 6 months of age). One additional child who tested positive by RT-PCR and whose mother had had rubella during pregnancy but who had a normal clinical examination was classified as having congenital rubella infection. During 2001-02 no rubella outbreaks were detected in Yangon Division. In the 31 urban townships of Yangon Division, the annual incidence was 0.1 laboratory-confirmed cases of CRS per 1000 live births. Conclusion This is the first population-based study of CRS incidence from a developing country during a rubella-endemic period; the incidence of CRS is similar to endemic rates found in industrialized countries during the pre-vaccine era. Rubella-specific IgG tests proved practical for diagnosing CRS in children aged > 6 months. This is one of the first studies to report on the use of rubellaspecific RT-PCR directly on serum samples; further studies are warranted to confirm the utility of this method as an additional means of diagnosing CRS. Voir page 18 le résumé en français. En la página 18 figura un resumen en español. Keywords

Rubella is a common cause of childhood rash and fever. Congenital rubella syndrome (CRS) can lead to deafness, heart disease, cataracts, and a variety of other permanent manifestations. In order to identify the disease burden of rubella infection, CRS surveillance among infants in Yangon was conducted for two consecutive years from December 2000 to December 2002, as a WHO-funded study. Among the 13 participating hospitals, the Special Care Baby Unit of the Central Women's Hospital in Yangon reported 17 infants with suspected CRS. Interestingly, three sets of twins with suspected CRS were reported. One ml of blood was collected from each infant after obtaining informed consent, then tested for the presence of rubella antibody (Immunoglobulin M and G) by the ELISA method, and for the presence of rubella viral RNA by the RT-PCR method. Furthermore, nucleotide sequencing and genotype identification of samples from two cases with positive rubella RNA were performed. All 3 sets of twins were IgM negative. However, rubella RNA was detected by RT-PCR in twin 1A who showed no obvious clinical signs, and in twin 2B who had patent ductus arteriosus, splenomegaly and hepatomegaly. Nucleotide sequences of PCR positive cases revealed genotype Ia sequences. Twin 2B was identified as having deafness of the left ear on audiometry assessment conducted at 5 years and 4 months of age. Both twins of twin set-2 were IgG positive at age 12 days, but turned out to be negative by the age of 9 months. Both twins of twin set-3 presented with splenomegaly and died before 2 months of age, probably due to other infections. Our findings revealed the different scenario of twins with suspected CRS. It is expected to serve as a valuable addition to the medical literature as there were very few reports on twins with CRS.