Widespread circulation of West Nile virus, but not Zika virus in southern Iran

Abstract

West Nile virus (WNV) and Zika virus (ZIKV) are mosquito-borne viral infections. Over the past few decades, WNV has been associated with several outbreaks involving high numbers of neuroinvasive diseases among humans. The recent re-emergence of ZIKV has been associated with congenital malformation and also with Guillain–Barre syndrome in adults. The geographic range of arthropod-borne viruses has been rapidly increasing in recent years. The objectives of this study were to determine the presence of IgG specific antibodies and the genome of WNV and ZIKV in human samples, as well as WNV and ZIKV genomes in wild-caught mosquitoes in urban and rural areas of the Hormozgan province, in southern Iran. A total of 494 serum samples were tested for the presence of WNV and ZIKV IgG antibodies using ELISA assays. One hundred and two (20.6%) samples were reactive for WNV IgG antibodies. All serum samples were negative for ZIKV IgG antibodies. Using the multivariable logistic analysis, age (45+ vs. 1–25; OR = 3.4, 95% C.I.: 1.8–6.3), occupation (mostly outdoor vs. mostly indoor; OR = 2.4, 95% C.I.: 1.1–5.2), and skin type(type I/II vs. type III/IV and type V/VI; OR = 4.3, 95% C.I.: 1.7–10.8 and OR = 2.7, 95% C.I.: 1.3–5.5 respectively, skin types based on Fitzpatrick scale) showed significant association with WNV seroreactivity. We collected 2,015 mosquitoes in 136 pools belonging to 5 genera and 14 species. Three pools of Culex pipiens complex were positive for WNV RNA using real-time reverse transcription polymerase chain reaction (rtRT-PCR). ZIKV RNA was not detected in any of the pools. All WNV ELISA reactive serum samples were negative for WNV RNA. In conclusion, we provided evidence of the establishment of WNV in southern Iran and no proof of ZIKV in serum samples or in mosquito vectors. The establishment of an organized arbovirus surveillance system and active case finding strategies seems to be necessary.

High Transmission Potential of West Nile Virus Lineage 1 for Cx. pipiens s.l. of Iran

“…Recent investigations have detected field-collected Cx. pipiens mosquitoes, infected with WNV in Iran [9,18]. However, despite many other signs of WNV circulation based on serological and molecular detections in humans, horses, birds, and mosquitoes, the vector competence of this species remains unknown in the country.…”

“…as the main WNV vector [24], humans, horses, and birds, confirmed the presence of the virus in the country [25]. There is much serological and molecular evidence of WNV circulation in vectors, animal reservoirs, and dead end hosts in Iran [9,17,18,[26][27][28][29][30]. Nevertheless, only few studies have succeeded in identifying the WNV lineages circulating in the country [15,17,18]: Cx.…”

“…WNV is now spread in Southern Asia, Northern Australia, Africa, and temperate regions of Europe [6,7]. The increasing traffic of goods and animals between countries offers multiple opportunities for the introduction of arboviruses in Iran, including WNV [8,9]. WNV is the most prevalent Culex-transmitted virus frequently reported in the country [10,11].…”

Detection of arboviruses in mosquitoes: Evidence of circulation of chikungunya virus in Iran

“…Mosquitoes of the main genera, Culex and Aedes are incriminated as the most important vectors of arboviruses [5,6]. The increasing volume of people displacements including movements of refugees, and the traffic of goods and animals between countries of the region, offer multiple opportunities for arbovirus introduction in Iran such as dengue virus (DENV), and West Nile virus (WNV) [7,8].…”

“…Chinikar et al, in 2012 and 2013, found that three patients developing encephalitis were positive for WNV by RT-qPCR assay [14] and detected serologically positive sera in 1.3% of humans and 2.8% of equines [15]. WNV was also detected in mosquitoes: Aedes caspius in the Northwest [16], and Culex pipiens in the North [17] and the South [8]. Besides, the most critical mosquito-borne virus in the world is DENV mainly transmitted between humans by Aedes mosquitoes [18].…”