Getah Virus (Alphavirus): An Emerging, Spreading Zoonotic Virus

Abstract

Getah virus (GETV) is a zoonotic virus transmitted by mosquitoes, belonging to the Togaviridae family, Alphavirus genus. It was first isolated from mosquitoes in Malaysia in 1955, being widespread in island countries in the South Pacific region. Since the beginning of the 21st century, GETV expanded its range and geographical distribution from low-latitude tropical regions to 60° north latitude, being isolated from 17 different species of mosquitoes belonging to five genera of Culicidae (Culex, Anopheles, Armigeres, Aedes and Mansonia), as well as from midges in Eurasia. Molecular genetic evolution analysis revealed large molecular differences between the mosquitoes currently circulating Eurasia and those in the South Pacific in 1950s. The number of disease outbreaks caused by GETV in animals is increasing alongside the types of animals infected, from horses and pigs to cattle, blue foxes and red pandas. The disease burden is severely underestimated, and the economic cost to livestock production remains unknown. Herein, we review GETV temporal and spatial distribution, molecular genetic evolution, transmission and data on disease outbreaks. This work provides a reference for public health workers engaged in GETV research and zoonotic disease prevention and control.

Keywords: Alphavirus; GETV; Getah virus; Togaviridae; emerging infection; molecular genetic evolution; virus spreading; virus transmission; zoonotic disease.

Figure 1

Geographical distribution of GETV: (A) Geographical distribution of GETV worldwide. (B) Geographical distribution of GETV in China. The orange area of (A) and (B) represents regions where GETV was present from 1955 to 1965. The light blue area of (A) is the current geographic distribution of GETV in Eurasia. The four colored circles (yellow, green, red and purple) represent the geographical distribution of GETV groups I, II, III and IV, respectively. Chinese provinces with animal host isolates are marked with different animal patterns on the figure (B). Chinese provinces: HLJ, Heilongjiang Province; JL, Jilin Province; LN, Liaoning Province; NMG, Neimenggu; XJ, Xinjiang; BJ, Beijing; TJ, Tianjin; HB, Hebei Province; SX, Shanxi Province; SaX, Shaanxi Province; GS, Gansu Province; QH, Qinghai Province; NX, Ningxia; SD, Shandong Province; SH, Shanghai; JS, Jiangsu Province; AH, Anhui Province; HeN, Henan Province; XZ, Xizang; ZJ, Zhejiang Province; JX, Jiangxi Province; HuB, Hubei Province; CQ, Chongqing; SC, Sichuan Province; HuN, Hunan Province; GZ, Guizhou Province; YN, Yunnan Province; FJ, Fujian Province; GD, Guangdong Province; GX, Guangxi; HaiN, Hainan; TW, Taiwan.

Figure 2

Phylogenetic analysis of GETV genes (E2). Using MEGA-X software, the neighbor-joining (NJ) method was used to draw the phylogenetic tree with 1000 bootstrap replicates. GETV can be divided into four groups (I–IV), of which group III can also be divided into three evolutionary branches (1–3). The animal host isolates are marked with different animal patterns on the figure and isolates without patterns were all isolated from mosquitoes.