Reemergence of Chikungunya virus in Indian Subcontinent

Abstract

Chikungunya virus (CHIKV), a reemerging arboviral disease of public health concern is characterized by a triad of fever, rash and arthralgia. It was responsible for a number of epidemics in Asia and Africa. The severity of the current epidemic can be judged by the fact that an estimated 1.38 million people in India and one-third of the La Reunion population (by April 2006) were affected by CHIKV. Aedes aegypti and Aedes albopictus are the major mosquitoes transmitting CHIKV in Asia. Various neurological complications and CHIKV associated deaths were encountered during the current outbreak (2005-2010). The aggressive nature of the recent CHIKV epidemic was attributed to the mutations in the viral genome in addition to their adaptation and spread to vectors like Aedes albopictus. Proper diet, adequate rest and symptomatic treatment using non-salicylate analgesics and Non-steroidal anti inflammatory drugs (NSAIDS) helped the patients in recovering from CHIKV infections. In the absence of an effective vaccine, rapid implementation of mosquito control measures and establishment of a system for continuous surveillance of the disease seems to be the only possible solution to prevent any such outbreak in the near future.

Keywords: Aedes mosquito; CHIKV; Co-infection; Differential diagnosis; Mutation; RT-PCR; Vaccine.

Fig. 1

Map of CHIKV confirmed states/Union territories in India from 2006 to 2009 (adapted from NVBDCP, Delhi. as on 31-12-2009). Shaded areas represent the affected states/UT. KL-Kerala; TN-Tamilnadu; PO-Pondicherry; KA-Karnataka; AP-Andhra Pradesh; GA-Goa; MH-Maharastra; OR-Orissa; MP-Madhya Pradesh; GJ-Gujarat; RJ-Rajasthan; WB-West Bengal; UP-Uttar Pradesh; DL-Delhi; HR-Harayana; LK-Lakshadweep Islands and AN*-Andaman and Nicobar Islands (* [34])

Fig. 2

Genome structure of Chikungunya virus. nsP1, nsP2, nsP3 and nsP4: Non-structural genes 1–4. C: Capsid gene (structural gene). E3, E2, E1: Envelope. genes (structural genes). 6K: (structural gene). J: Junction region. (A)_n: Poly A tail

Fig. 3

Chikungunya virus replication cycle

Fig. 4

Swelling of feet, a major symptom observed in Chikungunya infected female patients during the recent CHIKV epidemic in Tirupati

Fig. 5

Rashes on upper abdominal area of a CHIKV infected patient. Rashes along with fever and arthralgia are characteristic symptom of Chikungunya

Fig. 6

CHIKV detection by using the primer pair DVRChk-F/DVRChk-R which could amplify 330 bp E1 gene product. M: 1 Kb marker, Total RNA-L1: 180 ng; L2: 120 ng; L3: 60 ng; L4: 30 ng. CHIKV was detected from total RNA of infected patient up to 60 ng