Zika virus disease is a viral disease caused by the virus named as Zika Virus(ZIKV).This virus is an arbovirus and belongs to the family Flaviviridae.It possesses ssRNA.The virus got its name from the place of its discovery in 1947-Zika forest in Uganda.Monkeys act as the reservoirs of the virus.
Modes of transmission
The primary mode of transmission is Aedes aegypti mosquito.others may include mother-to-child transmission particularly in the first trimester.It is rarely transmitted through blood transfusion and organ transplantation.
Epidemiology
Zika virus infection has been reported in nearly 90 countries of the world.outbreaks have happened in Africa, America,Asia and other areas.The largest outbreak happened in Brazil in 2015-2016.It was reported in April 2015 in Brazil and then spread to other places like Australia,Europe, America,etc.Worldwide cases nearly 5 lakhs were reported during this period and the death toll stood at 20.About 2 lakh cases were reported from Brazil alone.
The WHO declared the Zika virus outbreak a public health emergency of international concern in February 2016.
Clinical manifestations
The incubation period of the virus ranges from few days to 1 week.Majority (80%) cases are without any symptoms.
- People with symptoms develop illnesses such as fever with rashes and conjunctivitis.
- Others develop microcephaly (A condition in which the infants head is smaller than the normal) - Congenital Zika Syndrome(CZS).
- In rare cases neuropathy and myelitis may also be seen.
Laboratory Diagnosis.
Nucleic acid testing (NAC):The investigation of choice is RT-PCR which can detect Zika virus RNA in blood upto 7 days of appearance of symptoms.
IgM antibody detection:IgM antibodies appear in blood after 1 week of symptoms and remains positive for several months.
Plaque-reduction neutralization test:It is a more specific serological test but it is not feasible to use,hence not used routinely.
Treatment:
There is no effective treatment or vaccine availability.Only symptomatic treatment is given which includes fluid replacement and analgesics such as acetaminophen.Vaccine trials are being conducted such as ZIKV DNA vaccine (VRC 705) which is called as ZIKV vaccine.Active research is going on with full pace and a licensed vaccine with higher efficacy may be available in the near future for eradication of this viral disease.
Preventive measures:They may include
Mosquito population control
Pregnant women should not travel to Zika virus affected areas.
Sex restriction for few months( 2-3) is also being advocated for men and women after travelling to areas with Zika virus outbreak.
Scenario in India:
India reported nearly 300 cases in 2018.The affected states included Rajasthan,Madhya Pradesh and Gujarat.
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