Professor Dr. Md. Abdul Khalique Barbhuiya
Editor-in-Chief
North East Medical Journal
Zika virus infection is an emerging mosquito-borne viral disease. The name Zika was obtained from the name of a forest of Uganda, where this virus was first isolated in 1947. That was first identified in rhesus monkeys through a monitoring network of sylvatic yellow level It was subsequently identified in human in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded un Africa, the Americas, Asia and the Pacific. Then Zika was spread from Africa to Asia till 1981. Until 2007 only 14 human cases of Zika virus infection was confirmed from Africa and South-East Asia. First outbreak of the disease outside Africa and Asia occurred in Yap Island of Micronesia in 2007, 49 cases were confirmed by virological test of patient’s serum in acute phase of illness. Further epidemics occurred in Oceania in between 2013-2014. Since April 2015, a large, ongoing outbreak of Zika virus that began in Brazil has spread to much of South and Central America and the Caribbean. 1,2
Epidemiology of disease: Agent: It’s a Group IV enveloped RNA virus of Flaviviridae family belongs to genera Flavivirus and species is Zika virus. Vector: Aedes mosquitoes (which usually bite during the morning and evening hours). But the true extent of mosquito is still unknown. Host:- the vertebrate hosts of the virus were primarily monkey, with occasional transmission to human. Reservoir: Unknown
Mode of transmission: i) vector born: transmitted to people through the bite of an infected female Aedes mosquito with an extrinsic incubation period in mosquito of about 10 days. ii) Sexual transmission: virus may remain in semen for long time after fade of symptoms. ii) Through blood can be transmitted through blood. iv) Transplacental: virus was found in the amniotic fluid and placenta of pregnant women and even the brain tissue of newborn (who died). v) Through breast milk: no such evidence was found. This is a new virus and the entire population is susceptible, which is a threat for rapid transmission of this disease.
Incubation period: The incubation period (the time from exposure to symptoms) of Zika virus disease is not clear, but is likely to be a few days.