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.