A report on the outbreak of Zika virus on Easter Island, South Pacific, 2014

Abstract

Zika virus (ZIKV) is an emerging mosquitoborne flavivirus circulating in Asia and Africa. In 2013, a large outbreak was reported on the archipelago of French Polynesia. In this study, we report the detection and molecular characterization of Zika virus for the first time in Chile from an outbreak among the inhabitants of Easter Island. A total of 89 samples from patients suspected of having ZIKV infection were collected between the period from January to May, 2014. Molecular diagnosis of the virus was performed by RT-PCR followed by the sequencing of the region containing the NS5 gene. A comparison of the viral nucleic acid sequence with those of other strains of ZIKA virus was performed using the MEGA software. Fifty-one samples were found positive for ZIKV by RT-PCR analysis. Further analysis of the NS5 gene revealed that the ZIKV strains identified in Easter Island were most closely related to those found in French Polynesia (99.8 to 99.9 % nt and 100 % aa sequence identity). These results strongly suggest that the transmission pathway leading to the introduction of Zika virus on Easter Island has its origin in French Polynesia.Keywords Zika virus Á Easter Island Á Outbreak Á South Pacific Á ZIKV Zika virus (ZIKV) is a mosquito-borne virus belonging to the family Flaviviridae and the genus Flavivirus. The Flaviviruses also include yellow fever, dengue, St. Louis encephalitis, West Nile, and Japanese encephalitis viruses [6]. ZIKV was first isolated from the blood of a sentinel rhesus monkey inhabiting the Zika Forest in Uganda [6]. Later on, ZIKV was isolated from a mosquito of the species Aedes africanus, obtained from the same locality of the Zika Forest. ZIKV has been isolated from several species of Aedes mosquito, notably, A. aegypti and A. albopictus [10]. A. aegypti is widely distributed in tropical and subtropical regions of the world [6,11,12].Clinically diagnosed ZIKV infections in human cases have been reported to include self-limiting acute febrile illnesses with fever, headache, myalgia, retro-orbital pain, arthralgia, conjunctivitis, and rash. These clinical presentations closely resemble those that are caused by dengue virus (DENV) and Chikungunya virus [6]. Serological studies and isolation of ZIKV strains have subsequently indicated that the virus has a wide geographical distribution, including regions in East and West Africa, South and South East Asia, and Micronesia [6], where an outbreak of Zika fever was reported on Yap Island [4]. In 2013, a Zika fever outbreak in French Polynesia was the largest ever reported for an arbovirus other than DENV at this location. Following this, there was a report of a Zika outbreak on the Cook Islands of New Caledonia [3,12].In Chile, at the end of 2000, the presence of A. aegypti on Easter Island was reported; the island is located on the east edge of the Polynesian Triangle, in the south Pacific Ocean, with a latitude of 27°9 0 10'' S, and a longitude of 109°27 0 17'' W [13]. The closest continental point from this island is the Chilean coast, l...

Sex, Mosquitoes and Epidemics: An Evaluation of Zika Disease Dynamics

“…Model (5) shows that migration is a determining factor for the spread of the disease. However, we can also see that the disease progresses through outbreaks, that, after a certain time practically go extinct, later appearing with less intensity, which it is consistent with the evolution of spread presented by the virus, appearing by outbreaks in different places (Duffy et al 2009;Macnamara 1954;Musso et al 2015;Tognarelli et al 2015;Yakoba and Walker 2016). The model allows us to predict what is expected of the disease in the future and underline the important role of migration.…”

“…In the American continent,the most important Flavivirus are Dengue virus, Yellow fever virus, St Louis encephalitis virus, Japanese encephalitis virus, West Nile virus B David Baca-Carrasco davidbaca@im.unam.mx Jorge X. Velasco-Hernández jx.velasco@im.unam.mx and Zika virus (ZIKV), transmitted by Aedes mosquitoes but could be also transmitted by other species, for example, Culex (Duffy et al 2009;ECDC 2015;Hayes 2009;Tognarelli et al 2015;Wikan 2016;Yakoba and Walker 2016).…”

“…The first report of human infection was in 1954 in Nigeria (Macnamara 1954); in 2007, the first large outbreak was reported in the Yap Island of the Federated States of Micronesia and the largest known outbreak before Brasil (Bogoch et al 2016;Campos et al 2015;ECDC 2015;Hennessey et al 2016) started in the French Polynesia, South Pacific (Duffy et al 2009;Musso et al 2015;Tognarelli et al 2015). Since then, the virus has spread very fast to large part of the Americas (Yakoba and Walker 2016).…”

“…aegypti, Ae.albopictus, Ae.africanus, Ae.luteocephalus, Ae.vitattus, Ae.furcifer, Ae.hensilii and Ae.apicoargenteus (Duffy et al 2009;ECDC 2015;Hayes 2009;Tognarelli et al 2015;Wikan 2016;Yakoba and Walker 2016). In the United States,the more widespread mosquito is Ae.albopictus constituting a risk for Zika spread.…”

Phylogenetic analysis revealed the central roles of two African countries in the evolution and worldwide spread of Zika virus

“…The first large outbreak of Zika disease in humans occurred on the Pacific island of Yap in the Federated States of Micronesia in 2007 (Lanciotti et al, 2008;Duffy et al, 2009). ZIKV was then identified from Suriname (Enfissi et al, 2016b) in South America, and on other Pacific Islands including French Polynesia (Berthet et al, 2014;Cao-Lormeau et al, 2014;Hancock et al, 2014), Easter Island of Chile (Tognarelli et al, 2015), the Cook Islands (Roth et al, 2014), and New Caledonia (Roth et al, 2014;Dupont-Rouzeyrol et al, 2015). Imported cases were also identified in countries of the Americas and Europe (Foy et al, 2011;Waehre et al, 2014;Zammarchi et al, 2015;Kindhauser et al, 2016).…”