Current Status of Chikungunya in India

Abstract

Chikungunya fever (CHIKF) is an arbovirus disease caused by chikungunya virus (CHIKV), an alphavirus of Togaviridae family. Transmission follows a human-mosquito-human cycle starting with a mosquito bite. Subsequently, symptoms develop after 2-6 days of incubation, including high fever and severe arthralgia. The disease is self-limiting and usually resolve within 2 weeks. However, chronic disease can last up to several years with persistent polyarthralgia. Overlapping symptoms and common vector with dengue and malaria present many challenges for diagnosis and treatment of this disease. CHIKF was reported in India in 1963 for the first time. After a period of quiescence lasting up to 32 years, CHIKV re-emerged in India in 2005. Currently, every part of the country has become endemic for the disease with outbreaks resulting in huge economic and productivity losses. Several mutations have been identified in circulating strains of the virus resulting in better adaptations or increased fitness in the vector(s), effective transmission, and disease severity. CHIKV evolution has been a significant driver of epidemics in India, hence, the need to focus on proper surveillance, and implementation of prevention and control measure in the country. Presently, there are no licensed vaccines or antivirals available; however, India has initiated several efforts in this direction including traditional medicines. In this review, we present the current status of CHIKF in India.

Keywords: Chikungunya fever (CHIKF); chikungunya virus (CHIKV); disease resolution; epidemiology; polyarthralgia.

FIGURE 1

(A) Simplified Phylogenetic tree of all Alphaviruses generated from partial E1 envelope glycoprotein gene sequences by using the neighbor-joining program Adapted from Powers et al. (2001) (BF, Burma Forest virus; CHIKV, chikungunya virus; SF, Semliki Forest; WEE, western equine encephalitis; EEE, eastern equine encephalitis; VEE, Venezuelan equine encephalitis; NDUV, Ndumu virus; ONNV, o’nyong’nyong virus; RRV, Ross River virus). (B) Phylogenetic tree of three genotypes of chikungunya viruses.

FIGURE 2

Diagnostic matrix followed by Indian clinicians for CHIKF and related coinfections (Lee et al., 2012).

FIGURE 3

Reported chikungunya outbreaks in India and Indian Ocean Islands (IOI) shows the year of onset of chikungunya outbreaks between 1963 and 2019 in India and the change in genotype from Asian (during the 1963–1973) to ECSA (2005–2019) is sketched in black and red triangles. The data source for generating. This figure is from NVBDCP (2014-15); National Health Profile (2019); National Center for Disease Control (2020).

FIGURE 4

Year-wise CHIKF cases in India with annual rainfall and temperature (2005–2018).