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Zika virus infection: Some issues of urgent attention

Published:August 18, 2016DOI:https://doi.org/10.1016/j.idh.2016.06.001

      Keywords

      Vector-borne Zika virus (ZIKV) infection is emerging as a leading public health threat. In the past few years, the infection hit various regions including Yap Island (Micronesia) [
      • Lanciotti R.S.
      • Kosoy O.L.
      • Laven J.J.
      • Velez J.O.
      • Lambert A.J.
      • Johnson A.J.
      • et al.
      Genetic and serologic properties of Zika virus associated with an epidemic, Yap State, Micronesia, 2007.
      ] and French Polynesia [
      • Cao-Lormeau V.M.
      • Blake A.
      • Mons S.
      • Lastere S.
      • Roche C.
      • Vanhomwegan J.
      • et al.
      Guillain-Barr Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study.
      ]. Subsequent reports of incidence have been received from Canada [
      • Fonseca K.
      • Meatherall B.
      • Zarra D.
      • Drebot M.
      • MacDonald J.
      • Pabbaraju K.
      • et al.
      First case of Zika virus infection in a returning Canadian traveler.
      ], United States [
      • Duffy M.R.
      • Chen T.
      • Hancock W.T.
      • Powers A.M.
      • Kool J.L.
      • Lanciotti R.S.
      • et al.
      Zika virus outbreak on Yap Island, Federated States of Micronesia.
      ] and recently from Brazil [
      • Zanluca C.
      • de Melo V.C.
      • Mosimann A.L.
      • Dos Santos G.I.
      • Dos Santos C.N.
      • Luz K.
      First report of autochthonous transmission of Zika virus in Brazil.
      ]. The testimony of ZIKV association with serious disorders such as microcephaly [
      • Oliveira Melo A.S.
      • Malinger G.
      • Ximenes R.
      • Szejnfeld P.O.
      • Alves Sampaio S.
      • Bispo de Filippis A.M.
      Zika virus intrauterine infection causes fetal brain abnormality and microcephaly: tip of the iceberg?.
      ] and Guillain-Barre syndrome [
      • Cao-Lormeau V.M.
      • Blake A.
      • Mons S.
      • Lastere S.
      • Roche C.
      • Vanhomwegan J.
      • et al.
      Guillain-Barr Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study.
      ] has made it a focus of health and disease monitoring organizations such as World Health Organization (WHO) and Centre for Disease Control and Prevention (CDC).
      ZIKV is a Flavivirus of family Flaviviridae. Genome of the virus is composed of single stranded positive sense RNA. ZIKV is primarily a mosquito-borne virus that is acquired by healthy human upon bite of a carrier mosquito. Important vector mosquito of ZIKV includes Aedes group members (A. aegypti, A. albopictus, A. furcifer, A. taylori, A. luteocephalus and A. africanus) [
      • Hayes E.B.
      Zika virus outside Africa.
      ]. Human to human transmission is possible by various modes. In addition to blood transfusion, sexual transmission was observed in the outbreak affecting French Polynesia [
      • Musso D.
      • Roche C.
      • Robin E.
      • Nhan T.
      • Teissier A.
      • Cao-Lormeau V.M.
      Potential sexual transmission of Zika virus.
      ]. Vertical transmission was reported from viremic mother to infant in another study [
      • Oliveira Melo A.S.
      • Malinger G.
      • Ximenes R.
      • Szejnfeld P.O.
      • Alves Sampaio S.
      • Bispo de Filippis A.M.
      Zika virus intrauterine infection causes fetal brain abnormality and microcephaly: tip of the iceberg?.
      ]. Being a relatively unexplored virus with limited focus in the past, several aspects demand immediate attention.
      The adequate detection of any pathogen is the preliminary step in disease diagnosis and treatment assignment. ZIKV diagnosis can be carried out through serological assay by detecting specific antibodies (IgM or IgG) or by detecting viremia in the blood with the help of RT-PCR [
      • Lanciotti R.S.
      • Kosoy O.L.
      • Laven J.J.
      • Velez J.O.
      • Lambert A.J.
      • Johnson A.J.
      • et al.
      Genetic and serologic properties of Zika virus associated with an epidemic, Yap State, Micronesia, 2007.
      ]. However, serological assay based diagnosis reported high cross reactivity with other flaviviruses [
      • Lanciotti R.S.
      • Kosoy O.L.
      • Laven J.J.
      • Velez J.O.
      • Lambert A.J.
      • Johnson A.J.
      • et al.
      Genetic and serologic properties of Zika virus associated with an epidemic, Yap State, Micronesia, 2007.
      ]. In another case study from Canada, it was revealed that ZIKV infected patient showed cross reactivity for Dengue IgM but not for subsequent IgG [
      • Fonseca K.
      • Meatherall B.
      • Zarra D.
      • Drebot M.
      • MacDonald J.
      • Pabbaraju K.
      • et al.
      First case of Zika virus infection in a returning Canadian traveler.
      ]. Amplification of genomic fragment then confirmed infection with ZIKV. Therefore, in the current scenario, when specificity and sensitivity of serological assays for ZIKV detection are not fully known, serological tests and RT-PCR should be performed in parallel to get a clear idea of active infection, particularly in regions where other flaviviruses have been reported.
      The transmission of ZIKV to the western territories became obvious when a medical volunteer on Yap Island during the ZIKV disease outbreak, got infected and returned to the United States [
      • Duffy M.R.
      • Chen T.
      • Hancock W.T.
      • Powers A.M.
      • Kool J.L.
      • Lanciotti R.S.
      • et al.
      Zika virus outbreak on Yap Island, Federated States of Micronesia.
      ]. Similarly, resident of Canada brought the infection to Canada from Thailand while returning back from Thailand [
      • Fonseca K.
      • Meatherall B.
      • Zarra D.
      • Drebot M.
      • MacDonald J.
      • Pabbaraju K.
      • et al.
      First case of Zika virus infection in a returning Canadian traveler.
      ]. Dissemination of ZIKV from geographically separate and distant regions of Yap Island and Thailand to western countries highlights the role of travel or commerce to spread the virus across wide distances. This situation emphasizes the need of effective check and surveillance system (a centrally connected online database having information of the infected individuals) at the trade and transit terminals for people from countries where ZIKV epidemics have been reported either previously or is active currently (Fig. 1). The phylogenetic analysis of the recent outbreak in Latin America revealed association with the French Polynesia outbreak [
      • Zanluca C.
      • de Melo V.C.
      • Mosimann A.L.
      • Dos Santos G.I.
      • Dos Santos C.N.
      • Luz K.
      First report of autochthonous transmission of Zika virus in Brazil.
      ] which indicates that trade, travel and people to people contact have possibly facilitated the transmission events.
      Figure thumbnail gr1
      Figure 1Regions with previous and current ZIKV infection as of February 2016 (retrieved from Center for Disease Control and Prevention).
      Effective eradication of associated vector is a known strategy in curtailing an infection efficiently. The monsoon season from July till September provides conducive period for mosquito breeding in tropical regions. Previously, one of the major ZIKV vectors, Aedes aegypti has remained a devastating agent in similar flavivirus outbreaks such as Dengue infection during the monsoon period [
      • Nasir S.
      • Jabeen F.
      • Abbas S.
      • Nasir I.
      • Debboun M.
      Effect of climatic conditions and water bodies on population dynamics of the Dengue vector, Aedes aegypti (Diptera: Culicidae).
      ]. In order to minimize the risk of local epidemics during monsoon, mosquito breeding sites must be properly eradicated and open water retaining reservoirs near residential areas must be covered or filled adequately. Apart from the seasonal factor overall environmental change and climatic conditions including global warming may be also a contributing factor in promoting ZIKV infection and related diseases vector mosquitoes at range of places and habitats [
      • Nasir S.
      • Jabeen F.
      • Abbas S.
      • Nasir I.
      • Debboun M.
      Effect of climatic conditions and water bodies on population dynamics of the Dengue vector, Aedes aegypti (Diptera: Culicidae).
      ] that are not limited anymore to tropics unlike the past.
      In broader perspective, there is an overall need of urgent measures at global level. These include initiatives to aware the public about the ZIKV infection via different available mediums. To be precise, residents of countries where the infection is currently active must ensure preventive strategies during sexual relations and proper screening before blood transfusion. Expecting mothers should avoid travel to affected areas and the use of mosquito repellents should be considered strictly. As there is no vaccine or proper medication for the infection currently, the scientific community should take immediate collaborative steps toward possible remedy. Big organizations like WHO and CDC should prioritize ZIKV infection on their agenda and provide grants to researchers for further studies to cope the situation wisely.

      Funding

      The study was self-funded.

      Conflict of interest

      The authors declare that there is no competing interest.

      Provenance and peer review

      Not commissioned; externally peer reviewed.

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