Co-infection of Dengue virus by serotypes 3 and 4 in patients from Amazonas, Brazil.

The natural co-infection with dengue virus can occur in highly endemic areas where different serotypes have been observed for many years. We report here four cases of DENV-3/DENV-4 co-infection detected by serological and molecular tests among 674 patients with acute undifferentiated fever from the tropical medicine reference center of Manaus City, Brazil, between 2005 and 2010. Analysis of the sequences obtained indicated the presence of genotype 3 and 1 for DENV-3 and DENV-4 respectively.

Phylogeny and molecular genetic parameters of different stages of hepatitis B virus infection in patients from the Brazilian Amazon.

A fragment of 600 bp of the gene which codes for the surface antigen of hepatitis B virus (HBV) was amplified and sequenced from patients who were born in five states of the Brazilian Amazon (Amazonas, Pará, Acre, Rondônia and Tocantins). A total of 44 sequences were used for the estimation of molecular genetic parameters and phylogenetic analyses. Compared with patients who were asymptomatic, those who had acute hepatitis and chronic liver disease had higher levels of genetic variability and higher rates of nucleotide substitutions.