Dengue and Chikungunya Virus Co-infections: The Inside Story.

INTRODUCTION: There have been various studies from India describing the acute presentation and the long-term sequalae of Chikungunya (CHIKV) infection. However, there are very few studies discussing the Chikungunya-Dengue (DENV) co-infection from Western India. The present project was undertaken to study the clinical features of Dengue and Chikungunya co-infection and compare with Chikungunya mono-infection; correlate the clinical findings with seroprevalence and molecular identification of Dengue and Chikungunya using IgM ELISA and RTPCR. MATERIAL AND METHODS: Three hundred suspected cases of Dengue and/or Chikungunya patients from out patients department and indoor wards, more than 12 years of age suffering from acute febrile illness, joint pains and rash for less than 10 days were included from June 2010 to April 2015. Proven cases of malaria, enteric fever, leptospirosis were excluded from the study. Leptospira IgM, Dengue IgM and PCR, Chikungunya IgM and PCR was done on all 300 samples. RESULTS: Sero-surveillance of the patients revealed that 59% (177) patients were positive for Dengue IgM alone, while 2% (6) tested positive for Chikungunya IgM alone. 6.7% (20) patients tested positive for Dengue and Chikungunya both. Ninty seven (32.3%) patients were negative for Dengue and Chikungunya. Of the 300 samples, 7% (21) were positive for DENV, 35% (105) were positive for CHIKV, 10% (30) were both DENV and CHIKV positive and 48% (144) were negative for both through RT-PCR. DISCUSSION: In our study, the patients of CHIKV mono-infection and DENV + CHIK co-infection had high VAS score, morning stiffness, arthralgias, restriction of joint movements as compared to patients with DENV mono infection. Patients of dengue mono infection had bone pains and myalgias in addition to joint pains; however there was restriction of joint movements in only 13.2% as compared with 100% of mono CHIKV or dual infection. These clinical features can be helpful in distinguishing DENV mono infection as compared to co-infection. The study highlights the diagnostic importance of RT-PCR in CHIKV and DENV co-infection, as 10% cases were identified using RT-PCR as compared to 6.7% cases by IgM antibodies.

Nine year trends of dengue virus infection in Mumbai, Western India.

INTRODUCTION: Dengue virus (DENV) causes a wide range of diseases in humans, from acute febrile illness Dengue fever (DF) to life-threatening Dengue hemorrhagic fever (DHF) or Dengue shock syndrome (DSS). Factors believed to be responsible for spread of Dengue virus infection include explosive population growth, unplanned urban overpopulation with inadequate public health systems, poor standing water and vector control, climate changes and increased international recreational, business, military travel to endemic areas. All of these factors must be addressed to control the spread of Dengue and other mosquito-borne infections. The detection of Dengue virus RNA by reverse transcriptase PCR (RT-PCR) in human serum or plasma samples is highly indicative of acute Dengue fever. Moreover, the method is able to identify the Dengue virus serotype by demonstrating defined sequence homologies in the viral genomic RNA. METHODS AND RESULTS: During the nine year period of this study analysis, 6767 strongly suspected cases were tested by RT-PCR. 1685 (24.9%) were Dengue PCR positive and confirmed as Dengue cases. Observations on the seasonality were based on the nine year's data as the intensity of sampling was at its maximum during monsoon season. Dengue typing was done on 100 positive samples after storage of Dengue RNA at - 80°C. Dengue serotypes were detected in 69 samples of which Dengue 2 was most predominant. 576 samples were processed for NS1 antigen and PCR simultaneously. 19/576 were positive (3.3 %) for NS1 as well as by PCR. 23/576 samples were negative for NS1 antigen, but were positive by RT-PCR. The remaining 534 samples which were negative for NS1 antigen were also negative by Dengue RT-PCR. CONCLUSION: In this study we sought to standardize rapid, sensitive, and specific fluorogenic probe-based RT-PCR assay to screen and serotype a representative range of Dengue viruses that are found in and around Mumbai. Qualitative Dengue virus TaqMan assays could have tremendous utility for the epidemiological investigation of Dengue illness and especially for the study of the viremic response with candidate live-attenuated dengue virus vaccines.