Zika Virus
Key facts:
- Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes.
- People with Zika virus disease can have symptoms including mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise or headache. These symptoms normally last for 2-7 days.
- There is scientific consensus that Zika virus is a cause of microcephaly and Guillain-Barré syndrome. Links to other neurological complications are also being investigated.
History of Zika Virus
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1947
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Scientists identify a new virus in a rhesus monkey in the Zika forest of Uganda - named as the Zika virus.
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1948
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The virus is then recovered from the mosquito Aedes africanus, caught in the Zika forest.
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1952
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The first human cases of Zika are detected in Uganda and the United Republic of Tanzania.
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1964
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A researcher in Uganda is infected with Zika while working on the virus confirming that Zika virus causes human disease. He reports the illness as "mild".
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1960-1980s:
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Human cases are confirmed through blood tests. No deaths or hospitalizations are reported, but studies consistently show widespread human exposure to the virus.
The disease is mapped as it moves from Uganda to western Africa and Asia in the first half of the 20th century.
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1969 - 1983
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Zika virus is detected in mosquitoes found in equatorial Asia, including India, Indonesia, Malaysia and Pakistan.
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2007
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First large Zika outbreak in humans in the Pacific Island of Yap in the Federated States of Micronesia.
Prior to this, no outbreaks and only 14 cases of human Zika virus disease had been documented anywhere in the world.
An estimated 73% of Yap residents are infected with Zika virus. The Yap Island outbreak also suggests a lack of immunity in the island's population. Regular exposure to infection by populations in Africa and Asia may have prevented the large outbreaks seen on Pacific Islands and in the Americas. Under-reporting, due to the clinical similarities of (mild) illness symptoms associated with Zika, dengue, and chikungunya infections might also account for previous Zika outbreaks being overlooked.
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2008
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A US scientist conducting field work in Senegal falls ill with Zika infection. On his return home to Colorado he infects his wife in what is the first documented case of sexual transmission of a disease usually transmitted by insects.
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2012
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Researchers identify 2 distinct lineages of the virus, African and Asian.
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2013-2014
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Outbreaks occur in 4 other groups of Pacific islands: French Polynesia, Easter Island, the Cook Islands, and New Caledonia.
Thousands of suspected infections are investigated in French Polynesia and results reveal possible associations between Zika virus and congenital malformations and severe neurological and autoimmune complications.
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20 March 2014
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During the outbreak of Zika virus in French Polynesia, 2 mothers and their newborns are found to have Zika virus infection within 4 days of birth. The infants' infections appear to have been acquired by transplacental transmission or during delivery.
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29 March 2015
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Brazil notifies WHO of an illness characterized by skin rash in northeastern states. From February 2015 to 29 April 2015, nearly 7000 mild cases are reported, with no reported deaths. Of 425 blood samples taken for differential diagnosis, 13% are positive for dengue. Tests for chikungunya, measles, rubella, parvovirus B19, and enterovirus are negative. Zika was not suspected at this stage, and no tests for Zika were carried out.
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11 November 2015
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WHO/PAHO issue an epidemiological alert asking countries to report increases of congenital microcephaly and other central nervous system malformations. Brazil reports the detection of Zika virus in amniotic fluid samples from 2 pregnant women, whose fetuses were confirmed by ultrasound examinations to have microcephaly.
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May 2017
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03 cases of Zika virus infection in Ahmedabad District, Gujarat, State, India.
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Signs and Symptoms:
The incubation period (the time from exposure to symptoms) of Zika virus disease is not clear, but is likely to be a few days. The symptoms are similar to other arbovirus infections such as dengue, and include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. These symptoms are usually mild and last for 2-7 days.
Prevention:
Mosquito bites
Protection against mosquito bites is a key measure to prevent Zika virus infection. This can be done by wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as window screens or closing doors and windows; sleeping under mosquito nets; and using insect repellent containing DEET, IR3535 or icaridin according to the product label instructions. Special attention and help should be given to those who may not be able to protect themselves adequately, such as young children, the sick or elderly. Travellers and those living in affected areas should take the basic precautions described above to protect themselves from mosquito bites.
It is important to cover, empty or clean potential mosquito breeding sites in and around houses such as buckets, drums, pots, gutters, and used tyres. Communities should support local government efforts to reduce mosquitoes in their locality. Health authorities may also advise that spraying of insecticides be carried out.
Sexual transmission
Zika virus can be transmitted through sexual intercourse. This is of concern due to an association between Zika virus infection and adverse pregnancy and fetal outcomes. For regions with active transmission of Zika virus, all people with Zika virus infection and their sexual partners (particularly pregnant women) should receive information about the risks of sexual transmission of Zika virus. WHO recommends that sexually active men and women be correctly counselled and offered a full range of contraceptive methods to be able to make an informed choice about whether and when to become pregnant in order to prevent possible adverse pregnancy and fetal outcomes. Women who have had unprotected sex and do not wish to become pregnant due to concerns about Zika virus infection should have ready access to emergency contraceptive services and counselling. Pregnant women should practice safer sex (including correct and consistent use of condoms) or abstain from sexual activity for at least the whole duration of the pregnancy.
For regions with no active transmission of Zika virus, WHO recommends practising safer sex or abstinence for a period of six months for men and women who are returning from areas of active transmission to prevent Zika virus infection through sexual intercourse. Sexual partners of pregnant women, living in or returning from areas where local transmission of Zika virus occurs should practice safer sex or abstain from sexual activity throughout the pregnancy.
Source & for more details:
http://www.who.int/mediacentre/factsheets/zika/en/
http://www.who.int/emergencies/zika-virus/history/en/
http://www.who.int/reproductivehealth/zika/zika-virus-research-agenda/en/
http://zikavirusnet.com/
www.cdc.gov/zika