Zika Virus Surveillance at the Human–Animal Interface in West-Central Brazil, 2017–2018

Abstract

Zika virus (ZIKV) was first discovered in 1947 in Uganda but was not considered a public health threat until 2007 when it found to be the source of epidemic activity in Asia. Epidemic activity spread to Brazil in 2014 and continued to spread throughout the tropical and subtropical regions of the Americas. Despite ZIKV being zoonotic in origin, information about transmission, or even exposure of non-human vertebrates and mosquitoes to ZIKV in the Americas, is lacking. Accordingly, from February 2017 to March 2018, we sought evidence of sylvatic ZIKV transmission by sampling whole blood from approximately 2000 domestic and wild vertebrates of over 100 species in West-Central Brazil within the active human ZIKV transmission area. In addition, we collected over 24,300 mosquitoes of at least 17 genera and 62 species. We screened whole blood samples and mosquito pools for ZIKV RNA using pan-flavivirus primers in a real-time reverse-transcription polymerase chain reaction (RT-PCR) in a SYBR Green platform. Positives were confirmed using ZIKV-specific envelope gene real-time RT-PCR and nucleotide sequencing. Of the 2068 vertebrates tested, none were ZIKV positive. Of the 23,315 non-engorged mosquitoes consolidated into 1503 pools tested, 22 (1.5%) with full data available showed some degree of homology to insect-specific flaviviruses. To identify previous exposure to ZIKV, 1498 plasma samples representing 62 species of domestic and sylvatic Viruses 2019, 11, 11643 of 18 vertebrates were tested for ZIKV-neutralizing antibodies by plaque reduction neutralization test (PRNT 90 ). From these, 23 (1.5%) of seven species were seropositive for ZIKV and negative for dengue virus serotype 2, yellow fever virus, and West Nile virus, suggesting potential monotypic reaction for ZIKV. Results presented here suggest no active transmission of ZIKV in non-human vertebrate populations or in alternative vector candidates, but suggest that vertebrates around human populations have indeed been exposed to ZIKV in West-Central Brazil.

High Rate of Non-Human Feeding by Aedes aegypti Reduces Zika Virus Transmission in South Texas

“…aegypti may play a role in D. immitis transmission, which warrants further research. Prior studies have also documented the potential spill-over of human-amplified urban arboviruses into wild or domestic animals [83,84], suggesting that Ae. aegypti could play the role of a bridge vector in this context.…”

The vertical stratification of potential bridge vectors of mosquito-borne viruses in a central Amazonian forest bordering Manaus, Brazil

“…Recently, some of these same monkey and mosquito species have been shown to be susceptible to experimental infection with ZIKV 10 – 13 , and ZIKV has been isolated from monkeys in suburban neighborhoods in Brazil 14 , 15 . However, the virus has not been isolated from free-living forest mosquitoes, although at present, only low-numbers of the most likely sylvatic vector species have been screened 16 , 17 .…”

Differential Longevity of Memory CD4 and CD8 T Cells in a Cohort of the Mothers With a History of ZIKV Infection and Their Children

“…This frequency of positivity was much lower than we expected, as were the data of Ribeiro et al Like in their study, our data cannot be attributed to problems in the execution of PRNT 90 , since the protocol established by Baer and Kehn-Hall ( 36 ) was strictly followed. The ZIKV/H.sapiens/Brasil/ES2916/2015 strain was identified in the State of Espírito Santo at the time of the CZS epidemic in Brazil ( 68 ). In a case report, it was shown that a child was positive for ZIKV IgG at birth and at the age of 12 months but was negative at 21 and 24 months of age.…”