A pilot study for serological evidence of hantavirus infection in human population in south India.

BACKGROUND AND OBJECTIVES: Hantaviruses are rodent-borne viruses of the family Bunyaviridae that have been identified as aetiological agents of two human diseases, haemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). There are no reports of hantavirus infections in humans from India, hence this pilot study was undertaken to provide the serological evidence of hantavirus infections in humans in south India. METHODS: Serum samples were obtained from individuals with acute febrile illness and from voluntary blood donors, majority of whom were from south India. Serum samples were tested for anti-hantavirus IgM using a commercial enzyme immunoassay (EIA). Samples found positive by the EIA were tested by an indirect immunofluorescence assay (IFA) using slides coated with Seoul virus (SEOV) infected cells as substrate. RESULTS: Of the 152 serum samples from individuals with pyrexic illness, 23 (14.7%) were positive for anti-hantavirus IgM by EIA. In contrast, only 5.7 per cent of healthy blood donors were positive by this assay. Eighteen of the 22 (82%) EIA-positive samples from patients were positive by the IFA assay. In contrast, only 2 of the 5 (40%) blood donor EIA positive samples were positive in the IFA assay. INTERPRETATION AND CONCLUSION: The finding of this study indicated the possible presence of hantavirus infections in the human population of India presenting both as asymptomatic and symptomatic infections. Further studies need to be done to confirm the findings on a larger sample using molecular techniques.

Subtype & cytokine profiles of HIV infected individuals from south India.

BACKGROUND & OBJECTIVE: The global surveillance of human immunodeficiency virus (HIV) subtypes (clades) helps understand the global distribution and incidence of different HIV subtypes. As knowledge about subtypes circulating in an area is needed for developing a candidate vaccine, prevalence of the subtypes HIV-1 and HIV-2 were studied in south India. The profile of cytokines interleukin 10 (IL10) and interferon gamma (IFNgamma) in both types of infection were also analysed as these are considered indicators of disease progression. METHODS: Patients who belonged to the 4 south Indian States i.e. Tamil Nadu, Kerala, Karnataka and Andhra Pradesh were included. HIV-1 subtyping was carried out by the heteroduplex mobility analysis (HMA) while that of HIV-2 was done by direct sequencing. The quantitation of IFNgamma and IL-10 was carried out using commercial ELISA kits. RESULTS: Among the 82 HIV-1 infected individuals subtyped, 78 (95.1%) were subtype C while all 12 HIV-2 strains were subtype A. IL-10 concentration was significantly higher among HIV infected individuals compared to normal healthy controls. IFNgamma was significantly higher among symptomatic and AIDS groups compared to asymptomatic HIV-1 infected individuals. INTERPRETATION & CONCLUSION: HIV-1 subtype C and the HIV-2 subtype A are the major subtypes circulating in south India. The study showed a trend towards a shifting of the cytokine profile from Th1 to Th2/Th0 in HIV-1, HIV-2 infections, and HIV-1 and HIV-2 dual infected individuals as the disease progresses. This trend observed is not unlike that reported from the West, despite the difference in subtype profile.

Is dengue emerging as a major public health problem?

BACKGROUND & OBJECTIVES: Diagnosis of dengue infection is easily and best accomplished by demonstration of specific IgM antibodies in blood. We analyzed retrospectively the dengue IgM seropositivity available for samples obtained over a period of five year (1999-2003) from patients with suspected dengue fever (DF)-like illness to investigate whether there was an overall increase in the dengue IgM prevalence over this period. METHODS: Serum samples from a total of 1426 individuals (suspected dengue cases) obtained over five year were tested for dengue specific IgM antibodies. Of the 1426 patients, 693 were adults (>15 yr) and 694 children (<15 yr) (excluding 39 individuals whose age was not known). There were 807 males and 610 females (excluding 9 individuals whose status on sex was unknown). RESULTS: A total of 423 (29.7%) samples were positive for dengue IgM over the five year period. Overall, there was a significant increase in the percentage of dengue IgM positive individuals over the this period (P<0.001). When the individuals were grouped into children (<15 yr) and adults (>15 yr), a significant increase in the number of dengue IgM positive individuals was noticed only in children (P<0.001) and not in adults. When the individuals were grouped into males and females, a significant increase in the number of dengue IgM positive individuals was noticed in both the sexes (P<0.03). Month-wise analysis of the dengue IgM positivity rates indicated the year-wide occurrence of dengue. A total of 158 (41%) of the dengue IgM positive individuals showed positivity for dengue IgG also suggestive of a secondary heterotypic infection. INTERPRETATION & CONCLUSION: The overall significant increase in dengue IgM seropositivity among the suspected cases indicates an increase in dengue virus activity, raising the question whether dengue is emerging/re-emerging as a major health problem in southern India. Increase in probable secondary infection (as evidenced by dual positivity for dengue IgM and IgG) seen in this study is also a point of concern. Such an increase especially in a country like ours where multiple serotypes are prevalent, raises concern over probable increase in the incidences of the more serious DHF/DSS. As this report could well be an underestimate of true incidence, the alarming increase observed in 2003, may be a warning/indication of epidemics to come soon that merits serious consideration.

Community prevalence of antibodies to human immunodeficiency virus in rural and urban Vellore, Tamil Nadu.

BACKGROUND: Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are becoming increasingly common in India. Currently, antenatal prevalence is a surrogate marker for HIV prevalence in the community. The association between antenatal and community prevalence of HIV needs to be validated so that estimates can be verified or adjusted appropriately. METHODS: A probability proportional to size cluster survey was conducted in the Kaniyambadi block of Vellore district and in the urban wards of Vellore town to estimate the prevalence of antibodies to rubella from August 1999 to February 2000. All personal identifier data from the serum samples were removed to yield a collection for which only the age and sex were known. Estimation of antibodies to HIV in sera from individuals between 15 and 40 years of age, was carried out by one screening ELISA and the reactive sera were further subjected to a supplementary test. RESULTS: We tested 1512 serum samples from subjects residing in rural areas and 1358 samples from those residing in urban areas. The seropositivity among rural samples was 0.66% and among urban samples 1.4%. The prevalence was almost equal among men and women and the youngest infected individual was 15 years old. CONCLUSION: The prevalence of HIV during the period of study was similar to the national surveillance data for Tamil Nadu based on antenatal women. HIV prevalence differs in urban and rural Tamil Nadu, with urban areas having a higher burden of the disease.

The immunological and virological response in human immunodeficiency virus type-1 (HIV-1) infected Indian individuals on haart therapy: A one-year follow up study.

Currently, antiretroviral therapy has become more affordable even in developing countries and it is being used in India. Fifteen HIV-1 infected individuals, who were on highly active antiretroviral therapy (HAART), were followed up for an average period of one year. The plasma viral load and CD4+ T cell estimation done at mean intervals of 5 months and 11 months after initiation of therapy showed a good response to therapy in 14 (93%) individuals.

Performance evaluation of four different kits available in the Indian market, for the rapid detection of HIV antibody.

The performance of four rapid human immunodeficiency virus (HIV) antibody screening assays was evaluated on an established panel of samples. All the assays showed 100% sensitivity and specificities in the range of 98.6-100%. These tests can safely be used for screening at centres in India where facilities are limited.