Vectors, Hosts, and Control Measures for Zika Virus in the Americas

Animals as potential reservoirs for dengue transmission: A systematic review

Dengue is a rapidly spreading mosquito-borne flavivirus infection that is prevalent in tropical and sub-tropical regions. Humans are known to be the main reservoir host maintaining the epidemic cycles of dengue but it is unclear if dengue virus is also maintained in a similar enzootic cycle. The systematic review was conducted in accordance to Cochrane's PRISMA recommendations. A search was done on PubMed, EMBASE, Scopus and Cochrane Library. Key data on animal dengue positivity was extracted and classified according to animal type and diagnostic modes. Of the 3818 articles identified, 56 articles were used in this review. A total of 16,333 animals were tested, 1817 of which were positive for dengue virus by RT-PCR or serology. Dengue positivity was detected in bats (10.1%), non-human primates (27.3%), birds (11%), bovid (4.1%), dogs (1.6%), horses (5.1%), pigs (34.1%), rodents (3.5%), marsupials (13%) and other small animals (7.3%). While majority of dengue positivity via serology suggests potential enzootic transmission, but regular dengue virus spillback cannot be excluded. With the exception of bats, acute infection among animals is limited. Further investigation on animals is critically required to better understand their role as potential reservoir in dengue transmission.

Analysis of Zika virus capsid-Aedes aegypti mosquito interactome reveals pro-viral host factors critical for establishing infection

The escalating global prevalence of arboviral diseases emphasizes the need to improve our understanding of their biology. Research in this area has been hindered by the lack of molecular tools for studying virus-mosquito interactions. Here, we develop an Aedes aegypti cell line which stably expresses Zika virus (ZIKV) capsid proteins in order to study virus-vector protein-protein interactions through quantitative label-free proteomics. We identify 157 interactors and show that eight have potentially pro-viral activity during ZIKV infection in mosquito cells. Notably, silencing of transitional endoplasmic reticulum protein TER94 prevents ZIKV capsid degradation and significantly reduces viral replication. Similar results are observed if the TER94 ortholog (VCP) functioning is blocked with inhibitors in human cells. In addition, we show that an E3 ubiquitin-protein ligase, UBR5, mediates the interaction between TER94 and ZIKV capsid. Our study demonstrates a pro-viral function for TER94/VCP during ZIKV infection that is conserved between human and mosquito cells.

Epidemic Alphaviruses: Ecology, Emergence and Outbreaks

Over the past century, the emergence/reemergence of arthropod-borne zoonotic agents has been a growing public health concern. In particular, agents from the genus Alphavirus pose a significant risk to both animal and human health. Human alphaviral disease presents with either arthritogenic or encephalitic manifestations and is associated with significant morbidity and/or mortality. Unfortunately, there are presently no vaccines or antiviral measures approved for human use. The present review examines the ecology, epidemiology, disease, past outbreaks, and potential to cause contemporary outbreaks for several alphavirus pathogens.

Linking Water Quality to Aedes aegypti and Zika in Flood-Prone Neighborhoods

The ability of ecosystems to regulate water quality and flood events has been linked to health outcomes, including mosquito-borne illnesses. In the San Juan Bay Estuary watershed of Puerto Rico, habitat alterations and land-use development have disrupted watershed hydrology, exacerbating wastewater discharges and subjecting some neighborhoods to frequent flooding events. In 2016, the mosquito-borne illness Zika became a new cause for concern. We hypothesized that nutrient-enriched flood water could provide pulses of supplemental nutrients to local mosquito populations. We conducted a field study in six neighborhoods adjacent to the estuary to assess whether environmental variability of nutrient inputs could be linked to breeding habitat containers, Aedes aegypti larvae and adults, and the acquisition of Zika virus by adult mosquitoes. The most frequently flooded neighborhood had consistently higher levels of nitrogen in estuary water, leaf detritus, containers, and adult mosquitoes compared to other neighborhoods. Adult body nitrogen was significantly related to both nitrogen content of containers and leaf detritus from the local trapping area. Disseminated Zika concentration in adult Ae. aegypti tended to decrease as body carbon and nitrogen increased. Our study provides preliminary evidence that environmental variability in nutrient inputs can influence viral acquisition by mosquito vectors. This suggests that management actions to reduce flooding and improve water quality should go hand-in-hand with more traditional vector control methods, such as aerial spraying, to help control spread of vector-borne diseases.

Zika Virus in Peridomestic Neotropical Primates, Northeast Brazil

Zika virus (ZIKV) is a mosquito-borne viral disease associated with fetal microcephaly and other central nervous system (CNS) symptomatology. It was first identified in a Rhesus macaque in Uganda in 1947 and later in humans (Zika fever). In 2015, ZIKV was notified in Northeast Brazil where it was associated with CNS alterations and with rapid epidemic spread. Considering that ZIKV infects Old World monkeys, the aim of this study was to follow its potential in neotropical primates. Here, we show the detection of ZIKV in marmosets and capuchin monkeys captured in Ceara state, Northeast Brazil. Nine (9/132) samples were positive by quantitative RT-PCR assay. Neutralizing antibodies in primates for ZIKV were also detected by PRNT. The ZIKV-positive samples were obtained from peridomestic animals captured in proximity to humans in areas with reports of ZIKV-associated microcephaly cases during the epidemic period. These results reiterate the molecular evidence of ZIKV infection in neotropical primates, and the temporal detection suggests that detection in primates occurred during the epidemic period in humans. However, a continuous surveillance is necessary to exclude the possibility of virus circulation and transmission in wild environments.

Zika Virus: A Global Public Health Menace: A Comprehensive Update

Zika virus (ZIKV) is a RNA virus and belongs to genus Flavivirus and family Flaviviridae. The virus was first discovered from a febrile primate from the Zika forests of Uganda in 1947 and the first human case was documented in 1954. The nonspecific clinical manifestations of ZIKV pose diagnostic dilemmas and delays early and effective treatment. Dental professionals should have a thorough knowledge about the virus and should follow standard infection control measures as the virus has been demonstrated in various body secretions (including salivary secretions). The disease is managed by symptomatic and supportive care and no vaccine exist till date. Recent ZIKV outbreaks and increase association of microcephaly with congenital ZIKV and neurological complications (Guillain-Barré syndrome) has drawn global public health attention. The World Health Organization declared it a public health emergency of international concern in 2016. This review article provides a detailed overview on ZIKV; it is clinical and oral manifestations, diagnostic aids, differential diagnosis, preventive aspects, and management protocol.