Molecular characterization of dengue viruses circulating during 2009-2012 in Uttar Pradesh, India.

Dengue is the most rapidly spreading mosquito-borne viral disease in the world; in India it has taken endemic proportion implicating all the four known dengue virus serotypes. Dengue infection is caused by a small, single stranded RNA virus comprising of four antigenically distinct virus serotypes designated as dengue virus type 1-4 (DENV-1-4). On the basis of genomic variations, each serotype is classified further into its genotypes. Epidemiological studies have shown that the emergence of a newer dengue serotype/genotype after an interval always leads to a major outbreak; therefore a continuous epidemiological surveillance is needed to monitor the epidemiology of dengue viruses. The present study was planned to identify the serotype/genotype of dengue viruses circulating in Uttar Pradesh, India. Of 433 dengue suspected patients, tested by reverse transcriptase PCR (RT-PCR), 136 were positive for dengue virus RNA. Of these, DENV-1, 2, and 3 were detected in 26 (19.1%), 77 (56.6%), and 33 (24.3%) patients, respectively. Of 136 RT-PCR positive samples, 24 samples were sequenced to identify their genotypes. For sequencing C-prM gene junction of dengue virus genome was chosen. Phylogenetic analysis of sequenced dengue strains revealed that all the 12 DENV-1 strains were genotype III, all the eight DENV-2 strains were genotype IV (Cosmopolitan genotype) and among four DENV-3 strains, three were genotype III and one was genotype I. In conclusion, the co-circulation of multiple dengue virus serotypes and genotypes is alarming in U.P., India.

Co-positivity of anti-dengue virus and anti-Japanese encephalitis virus IgM in endemic area: co-infection or cross reactivity?

OBJECTIVE: To report high co-positivity of anti-dengue virus (DV) and anti-Japanese encephalitis virus (JEV) IgM in an area endemic for both the viruses and to discuss the possibilities of co-infection. METHODS: Serum samples from the patients who presented with fever, suspected central nervous system infection and thrombocytopenia, were tested for anti-DV IgM and anti-JEV IgM antibodies. Conventional reverse transcriptase polymerase chain reaction was done for detection of DV RNA and JEV RNA. RESULTS: Of 1 410 patient sera tested for anti-DV and anti-JEV antibodies, 129 (9.14%) were co-positive for both. This co-positivity was observed only in those months when anti-JEV IgM positivity was high. Titers of both anti-DV IgM and anti-JEV IgM were high in most of the co-positive cases. Among these 129 co-positive cases, 76 were tested by conventional reverse transcriptase polymerase chain reaction for both flaviviruses, of which eight cases were co-positive for DV and JEV. CONCLUSIONS: Co-infection with more than one flavivirus species can occur in hyperendemic areas.

Trend of dengue virus infection at Lucknow, north India (2008- 2010): a hospital based study.

BACKGROUND & OBJECTIVES: Dengue virus (DV) infection has emerged as a major health problem in north India. Here, we report the annual trend of dengue virus infection as seen in Lucknow, Uttar Pradesh, during 2008-2010. METHODS: Blood samples from clinically suspected cases of dengue virus infection were collected and history was taken on structured clinical data sheet. All samples were tested for dengue IgM by antibody capture ELISA. Selected samples were tested by conventional RT-PCR for dengue virus RNA. Weather information was continuously recorded from website of world weather information service . RESULTS: There was a gradual increase in number of dengue fever cases with increased occurrence in 2010. Cases referred in January - December 2008 were 398 (54.5% anti DV IgM positive), in January - December 2009 were 599 (51.9% anti DV IgM positive) and in January - December 2010 were 1602 (64.9% anti DV IgM positive). Serotypes circulating in years 2008, 2009 and 2010 were DV-2 & DV-3, DV -1, 2 & 3 and DV-1 and DV-2 respectively. There is no statistical significant correlation between weather data and increasing dengue positive cases. INTERPRETATION & CONCLUSIONS: Increased cases of dengue fever were seen in 2010, which was not correlated with any change in environmental factors. A change in circulating serotypes was noted.