Anita Chakravarti

Eco-epidemiological analysis of dengue infection during an outbreak of dengue fever, India

BackgroundThis study was designed to find out a relationship of dengue infection with climatic factors such as rainfall, temperature and relative humidity during the dengue fever epidemic in the year 2003. Blood samples were collected from 1550 patients experiencing a febrile illness clinically consistent with dengue infection. Serological confirmation of Dengue Infection was done using Dengue Duo IgM and IgG Rapid Strip test (Pan Bio, Australia), which detected dengue-specific antibodies. Monthly data of total rainfall, temperature and relative humidity for the year 2003 was obtained from Meteorological Department of Delhi, New Delhi and retrospectively analyzed.ResultsOut of 1550 suspected cases, 893 cases (57.36%) were confirmed as serologically positive. The difference between numbers of serologically positive cases during different months was significant (p < 0.05). Larger proportions of serologically positive cases were observed among adults. Outbreak coincided mainly with the post monsoon period of subnormal rainfall. The difference between serologically positive cases as compared to serologically negative ones in post monsoon period was significantly higher (p < 0.001). The difference in the rainfall and temperature between three seasonal periods was significant (p < 0.05).ConclusionThis prospective study highlighted rain, temperature and relative humidity as the major and important climatic factors, which could alone or collectively be responsible for an outbreak. More studies in this regard could further reveal the correlation between the climatic changes and dengue outbreaks, which would help in making the strategies and plans to forecast any outbreak in future well in advance.

Fifty years of dengue in India

Dengue is the most important mosquito-borne, human viral disease in many tropical and sub-tropical areas. In India the disease has been essentially described in the form of case series. We reviewed the epidemiology of dengue in India to improve understanding of its evolution in the last 50 years and support the development of effective local prevention and control measures. Early outbreak reports showed a classic epidemic pattern of transmission with sporadic outbreaks, with low to moderate numbers of cases, usually localized to urban centres and neighbouring regions, but occasionally spreading and causing larger epidemics. Trends in recent decades include: larger and more frequent outbreaks; geographic expansion of endemic transmission; spread of the disease from urban to peri-urban and rural areas; an increasing proportion of severe cases and deaths; and progression to hyperendemicity, particularly in large urban areas. The global picture of dengue in India is currently that of a largely endemic country. Understanding demographic differences in infection rates and severity of dengue has important implications for the planning and implementation of effective public health prevention and control measures and targeting of future vaccination campaigns.

Polymorphism of tumor necrosis factor–α and interleukin-10 gene promoter region in chronic hepatitis C virus patients and their effect on pegylated interferon–α therapy response

The development and resolution of an inflammatory process is regulated by a complex interplay among cytokines that have pro- and anti-inflammatory effects. Regulatory mechanisms that control the production of cytokines include genetic polymorphism in particular promoter/leader region. Polymorphisms may directly or indirectly affect the binding of transcriptional factors, consequently increasing or decreasing the production of mRNA, thus regulating cytokine production. A total of 70 hepatitis C virus (HCV) RNA-positive patients and 70 healthy control subjects were included in the present study, who were attending the medical outpatient department (OPD) and wards of a tertiary care hospital in New Delhi during 2006-2008. This study was designed to determine the polymorphism of tumor necrosis factor-α and interleukin-10 genes in patients with chronic HCV infection patients and their effect on pegylated interferon-α therapy response. Polymorphism in the tumor necrosis factor-α G/G, G/A, and A/A genotype was significant between HCV patients and healthy controls. Interleukin-10 variants (G/G, G/A) were nonsignificant among HCV patients compared with healthy controls. As this is a preliminary study on small sample size, we believe that our findings may stimulate further studies on larger number of patients from this geographic region.

Chikungunya: a review:

SUMMARY The Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus, which causes epidemics of fever, rash and polyarthralgia in Africa and Asia. First isolated in 1953 in Tanzania, CHIKV has caused numerous well-documented outbreaks and epidemics in both Africa and South-East Asia. The epidemic of Chikungunya fever that affected the population of La Reunion at Christmas in 2005 will be remembered as the most serious public health crises in the islands history. A widely circulating mutant CHIKV is a possible explanation for the epidemiological pattern of the disease in this region. In this review, we have tried to give the latest information about the present outbreak and have tried to analyse the possible reasons for the same.

Awareness of changing trends in epidemiology of dengue fever is essential for epidemiological surveillance

Dengue has become endemic in India with outbreaks occurring almost every year. The seroprevalence and serotypic data of the last 7 years in samples obtained from suspected dengue patients from a tertiary care hospital were analyzed. Out of 7846 serum samples received in the virology laboratory from suspected dengue cases during 2002 to 2008, 2366 (30.15%) were serologically confirmed. Serotyping was done using mRT-PCR. All the four serotypes were detected in 2003, while data in 2004, 2005 and 2006 revealed the the predominance of Den-3. In the year 2007 predominance of Den-2 was observed, whereas in 2008 Den-1 was the most common serotype isolated. Overall, Den-2 and Den-3 were the most predominant serotypes during 2003-2007 but Den-1 replaced these strains in the year 2008. Since the emergence of a new predominant strain can lead to the occurrence of an outbreak, presence of Den-1 in the year 2008 would pose an alarming situation before us. Well-targeted population-based epidemiological studies are urgently required to control dengue menace.

Seroprevalence of hepatitis viruses in patients infected with the human immunodeficiency virus.

OBJECTIVE The co-infection of Hepatitis B and C viruses with HIV accelerates disease progression and also has an effect on the management of patients infected with HIV. The prevalence of HIV co-infection with hepatitis viruses varies widely. This study is planned to evaluate the prevalence of HIV co-infection with Hepatitis B and C viruses in North India. MATERIALS AND METHODS A total of 1178 patients enrolled in the ART center were retrospectively analyzed for the presence of HBV and HCV on the basis of the presence of HBsAg and anti-HCV markers. RESULTS In patients infected with HIV, the prevalence of co-infection with HBV was 9.9% (117/1178), the prevalence of co-infection with HCV was 6.3% (74/1178) and the prevalence co-infection with both HBV and HCV was ~1% (12/1178). DISCUSSION The prevalence rate of HBV and HCV are increasing in patients infected with HIV. Having acquired the knowledge about the importance of such a co-infection, it is essential that all the patients infected with HIV be screened for HBV and HCV co-infection.

Genotypic characterization of hepatitis C virus and its significance in patients with chronic liver disease from Northern India

The characterization of hepatitis C virus (HCV) strains has important prognostic, therapeutic, and epidemiologic implications. The present study was intended to determine the HCV genotypes from Northern India in chronic liver disease (CLD) patients. The response to therapy in various subtypes was also evaluated in patients with chronic hepatitis. Furthermore, the genotypes were correlated with the biochemical and histopathologic parameters to assess the severity of liver disease. Five milliliter of blood sample was collected aseptically from 98 patients with CLD due to hepatitis C. Genotyping was performed by restriction fragment length polymorphism and type-specific polymerase chain reaction, followed by direct sequencing. The HCV genotypes depicted were 1a (6.12%), 1b (8.16%), 1c (8.16%), 3a (17.34%), 3b (6.12%), 3a + 3b (40.81%), 3a + 1b (7.14%), and an unclassified type of 6.12%. The present study revealed that HCV genotype 3 is the predominant one, with 40.81% (40/98) being a mixed type of 3a with 3b and identification of newer subtype 1c. HCV subtypes 1a, 3a, and 3b are responding to therapy, whereas 1b (40%, 2/5), 1c (66.67%, 2/3), 3g (33.3%, 1/3), 3a + 3b (41.6%, 5/12), and mixed type 3a + 1b (66.67%, 4/6) are poor responders to therapy. The biochemical profiles were higher in mixed type followed by types 3 and 1, whereas the histologic parameters revealed that the severity of liver disease was more in mixed type followed by types 1 and 3, which also showed poor response to therapy.

Evaluation of three commercially available kits for serological diagnosis of dengue haemorrhagic fever

Seventy one acute phase serum samples collected during an epidemic of dengue hemorrhagic fever were tested by immunoblot, a rapid immunochromatographic assay and Dengue Duo ELISA for presence of anti dengue IgM and IgG antibodies. A concordance of 81.7% and 76.1% was seen between the three tests for the detection of anti-dengue IgM antibodies and IgG antibodies respectively. The rapid test takes only five minutes, can be easily carried out in most laboratories and compares well with the ELISA and the immunoblot.

Immunodiagnosis of Dengue Virus Infection Using Saliva

Keeping in view the complications and the case fatality associated with dengue virus, several serologic tests have been developed. However, the major drawback of these serologic tests is the need for a venous blood sample obtained by invasive venipuncture. As a noninvasive alternative, saliva provides a body fluid that contains antibodies of diagnostic importance. Hence, the detection of DEN-specific IgM and IgG antibodies in serum and saliva from 80 patients was compared. Salivary IgM antibodies were detected in 100% of the serum IgM-positive samples and in 30% of the serum samples that were negative for IgM antibodies. Salivary IgG antibodies were detected in 93.3% of the serum samples that were positive for anti-dengue IgG antibodies and in none of the serum IgG-negative cases. None of the specimens from the healthy controls showed the presence of IgM or IgG antibodies. The detection of both IgG and IgM antibodies in saliva correlated well with the serum IgG and IgM detection by the ELISA test (r = 0.6322 and r = 0.4227). Detection of salivary IgM antibodies by ELISA showed 100% sensitivity, 70% specificity, 90.9% positive predictive value, and 100% negative predictive value. The detection of IgG in saliva proved to be a promising tool as the sensitivity, specificity, positive predictive value, and negative predictive value were found out to be 93.3%, 100%, 100%, and 83.3%, respectively. Thus, from this study we conclude that the detection of DEN-specific salivary IgG and IgM antibodies are useful markers for dengue infection.

Cytokine Levels of TGF-β, IL-10, and sTNFαRII in Type C Chronic Liver Disease

Cytokines play a key role in regulation of immunity and inflammation. The aim of the study was to detect serum levels of TGF-β, IL-10, and sTNFαRII in patients with type C chronic liver disease (CLD) and to correlate these with biochemical and histopathological parameters used to assess the severity of the disease. Blood samples were aseptically collected from 90 CLD patients. Cytokine levels were also followed up in 39 chronic hepatitis cases. Levels of the cytokines in 90 CLD patients were significantly higher than in controls. In the follow up patients, 12 were non-responders and the serum levels of cytokines were still elevated after therapy whereas in 27 responders cytokine levels were significantly reduced after therapy and correlated well with biochemical and histopathological parameters. It is inferred that cytokine levels reflect the level of inflammation in chronic hepatitis C virus (HCV) infection and can be used as indirect markers to assess the severity of liver disease.