Emergence of Chikungunya Virus, Pakistan, 2016–2017

Abstract

C hikungunya is a vectorborne viral disease that causes large outbreaks, mainly in tropical and subtropical countries (1). The term chikungunya is derived from a word in the Makonde language (spoken in parts of Tanzania and Mozambique, Africa), kungunyala, meaning "that which bends up," referring to the stooped posture and impaired gait patients exhibit because of severe joint pain (2). Chikungunya virus (CHIKV; family Togaviridae, genus Alphavirus) is an enveloped, single-strand, positive-sense RNA virus transmitted through the bite of infected Aedes mosquitoes, predominantly Ae. aegypti and Ae. albopictus (2). West African, East/Central/South African (ECSA), and Asian CHIKV genotypes are distinguished by envelope 1 (E1) glycoprotein phylogeny. In 2005, a major outbreak in countries around the Indian Ocean was caused by the ECSA genotype (3). Virus mutations facilitated its replication in Ae. albopictus mosquitoes and its rapid spread by Ae. albopictus and Ae. aegypti mosquitoes (3), species prevalent in Pakistan during and after monsoon season, May-September. In Pakistan, CHIKV was reported to be circulating in rodents as early as 1983 (4), but few human cases were reported. During a 2011 dengue outbreak in Lahore, some patients also had CHIKV antibodies. CHIKV emerged in Karachi during 2016, and an outbreak eventually was declared when evidence of local transmission was confirmed (5). We reviewed the epidemiologic and evolutionary links of CHIKV detected during December 2016-May 2017 across Pakistan. The Study We tested serum samples from 584 patients with suspected CHIKV infection, according to the World Health Organization case definition (6). Patients were seen in different hospitals and clinics during December 20, 2016-May 31, 2017. Patients had acute onset fever (temperature >38.5°C), rash, and severe arthralgia or arthritis <7 days after a mosquito bite. Clinical signs and symptoms included fever in 90% (523/584) of persons with suspected cases, headache in 65% (382/584), joint pain in 85% (497/584), and rash in 24% (141/584) (Appendix Table 1, https://wwwnc. cdc.gov/EID/article/26/2/17-1636-App1.pdf). We used a predesigned form to collect patient demographic data, clinical information, and travel histories. We identified 495 (84.7%) suspected cases in Sindh, 52 (8.9%) in Baluchistan, 10 (1.7%) in Federal Capital Territory, 10 (1.7%) in Punjab, and 17 (2.9%) in Khyber Pakhtunkhwa (Figure 1). We used the QIAmp Viral RNA Mini Kit (QIAGEN, https://www.qiagen.com) to extract RNA from serum samples, according to the manufacturer's protocol. We conducted one-step real-time reverse transcription-PCR (rRT-PCR) on the ABI7500 platform (Applied Biosystems, https://www.thermofisher.com) following guidelines from the U.S. Centers for Disease Control and Prevention emergency use authorization for Trioplex Real-Time RT-PCR assay (7). We used CHIKV-specific oligonucleotide primers to detect and sequence the envelope 1 (E1) and nonstructural protein 1 (NSP1) genes (8). We conducted phylogenetic analysis of partial E1 (n...

Chikungunya Manifestations and Viremia in Patients Who Presented to the Fever Clinic at Bangkok Hospital for Tropical Diseases during the 2019 Outbreak in Thailand

“…Chikungunya virus has re-emerged in many parts of the world and is considered to be a continuous global threat [ 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. The reason for this resurgence is not fully elucidated, but is believed to be multifactorial, such as increased vector susceptibility and perhaps climate change [ 6 , 61 , 62 ].…”

Chikungunya Manifestations and Viremia in Patients Who Presented to the Fever Clinic at Bangkok Hospital for Tropical Diseases During the 2019 Outbreak in Thailand

“…Chikungunya virus has re-emerged in many parts of the world and is considered to be a continuous global threat (32,(46)(47)(48)(49)(50)(51)(52)(53). The reason for this resurgence is not fully elucidated, but is believed to be multifactorial, such as increased vector susceptibility and perhaps climate change (6,54,55).…”

Cytokines and Chemokines in Chikungunya Virus Infection: Protection or Induction of Pathology

“…Then, in 2013-2014, CHIKV was introduced to the Latin Americas [6]. Since then, CHIKV re-emerged in India with the ECSA (226A) strain in 2015, in Pakistan and Bangladesh in 2016-2017 [7][8][9] and in Thailand in 2018-2019 [10].…”