ZIK VIRUS AS A PRIME EXAMPLE OF EMERGENT INFECTIONS

Abstract

The recent development of technologies of the laboratory systems in microbiology, providing detailed genome sequencing, has paved the ways for isolating new pathogens and carrying out in-depth study of long-known microorganisms. Moreover, the progressing of science and technology contributes to study changes in the ecology of microorganisms and the epidemiological characteristics of their spreading over the world. These advances enable scientists to find out some "new" diseases, known as emergent infectious diseases. Emergent diseases have emerged as a new type of rapidly evolving, long-known infectious diseases. A prime example of an emergent infection is the Zika virus (ZIKV). ZIKV belongs to the family Flaviviridae of the Flavivirus genus. It was first isolated from the blood of a rhesus macaque in 1947 in East Africa (Uganda), in the Zika forest, where its name came from. A year later, in the same area, ZIKV was detected in mosquitoes of the Aedes africanus genus. For a long time following the initial isolation of ZIKV, isolated sporadic cases of the disease caused by this pathogen were recorded in Asia and Africa. In 2007, an ZIKV outbreak was reported on the island of YAP (Micronesia). This was the first outbreak outside Asia and Africa. Zika virus is primarily transmitted by the bite of an infected mosquito from the Aedes genus in tropical and subtropical regions. But according to literature data, this virus can be spread by 17 species of mosquitoes of this genus. AE. aegypti and Ae. Albopictus have been known a leading role of spreading the infection. Considering that these mosquitoes are not only carriers of ZIKV, but also some other flavivirusiv representatives, their wide geographical distribution has become an issue of great concern. AE. aegypti mosquitoes are thermophilic and live only in tropical and subtropical climate zones and this fact has played as significant rope in the ZIKV spread. Ae. albopictus mosquitoes promote the circulation of this pathogen and cause a rapid expansion of the virus in the world, since this species has become widely distributed in countries of subtropical and temperate climate zones. To date, besides the main vector-borne transmission of the virus, there are a number of reports about ZIKV transplacental transmission from an infected mother to the foetus. ZIKV caused viral infection during the pregnancy results in microcephaly, a congenital condition associated with incomplete brain development and abnormally small size of the skull. This viral infection can also lead to such complications as miscarriage, stillbirth, and premature birth. According to the literature, there is the connection between ZIKV and not congenital CNS abnormalities, but also with Guillain-Barre syndrome. There have been publications on not only ZIKV mosquito transmission and transplacental transmission, but a few reports on ZIKV sexual transmission when no barrier contraceptives are used. ZIKV can be isolated from ejaculate within 14-28 days from the onset of the first symptoms of the disease.