Chikungunya Fever Outbreak, Bhutan, 2012

Sonam Wangchuk, Piyawan Chinnawirotpisan, Tshering Dorji, Tashi Tobgay, Tandin Dorji, In-Kyu Yoon, and Stefan Fernandez

Author affiliations: Ministry of Health, Thimphu, Bhutan (S. Wangchuk, T. Dorji, T. Tobgay, T. Dorji); Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand (P. Chinnawirotpisan, I.-K. Yoon, S. Fernandez)

Abstract

In 2012, chikungunya virus (CHIKV) was reported for the first time in Bhutan. IgM ELISA results were positive for 36/210 patient samples; PCR was positive for 32/81. Phylogenetic analyses confirmed that Bhutan CHIKV belongs to the East/Central/South African genotype. Appropriate responses to future outbreaks require a system of surveillance and improved laboratory capacity.

Chikungunya fever is caused by infection with chikungunya virus (CHIKV; family Togaviridae, genus Alphavirus). CHIKV was first isolated from humans and mosquitoes during an epidemic of chikungunya fever in Newala, Tanzania, during 1952–1953 (1). The virus is transmitted to humans primarily by Aedes aegypti and Ae. albopictus mosquitoes. Chikungunya fever can cause lingering joint pain, often lasting several weeks; the disease is rarely life-threatening and, unlike dengue virus infection, does not cause severe hemorrhagic manifestations or shock (2). Outbreaks of chikungunya fever are sporadic, and there is no licensed vaccine to protect against the disease.
In addition to the chikungunya fever epidemic in Tanzania in 1952–1953, several other outbreaks have affected millions of persons in eastern, western, and central Africa and Asia. The first of many chikungunya fever outbreaks in Southeast Asia was reported in Bangkok, Thailand, in 1958, followed by outbreaks in Sri Lanka; Kolkata and Chennai, India; and elsewhere (3–6). CHIKV reemergence in Indonesia and India caused epidemics during 1999–2003 and 2005–2006, respectively; 1.3 million cases of chikungunya fever occurred in India during the epidemics (6,7). In 2004, a chikungunya fever outbreak occurred in the Indian Ocean region. On Réunion Island, 266,000 cases, affecting ≈40% of the population, and ≈250 deaths were recorded (7). We report details of a chikungunya fever outbreak in Bhutan in July 2012; CHIKV had not been reported in Bhutan before this outbreak.