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Briefing notes on Zika and Microcephaly

Status of the Zika Virus Outbreak

  • Zika virus is currently present in 18 countries in the Americas, and in a number of countries in Africa and the Western Pacific.

  • The virus is transmitted by the same mosquito that also transmits 3 other diseases -- dengue, chikungunya and yellow fever – across tropical and subtropical regions around the world. Symptoms and Treatment of Zika Virus Infection

  • Zika virus infection is known to cause headache, muscle and joint pain, mild fever, rash and inflammation of the underside of the eyelid. These symptoms are usually mild, and last 2 to 7 days.

  • WHO recommends that anyone sickened by Zika virus disease get rest, drink plenty of fluids, and treat pain and fever with common medicines.

  • There is no treatment for the virus itself; If symptoms worsen, people sickened with virus should seek medical care and advice.

Possible relationship of Zika to microcephaly

  • In Brazil, public health workers reported 3530 cases of microcephaly from the beginning of 2015 through the first week of 2016. The cases, which included 46 deaths, occurred in 20 states of Brazil and the Federal District.

  • The incidence of microcephaly appears to be increasing in Brazil, where an average of just 163 microcephaly cases was recorded per year between 2010 and 2014.

  • Microcephaly is a condition in which a child is born with an abnormally small head. Such children often have brain development issues

  • Microcephaly can be caused by a variety of genetic and environmental factors such as Down syndrome; exposure to drugs, alcohol or toxins in the womb; and chickenpox or rubella infection during pregnancy.

  • Although there is an increasing number of microcephaly cases, the causal link between Zika infection and microcephaly has not yet been proven.

  • Among the evidence suggesting a link between microcephaly and Zika virus infection is a report from Brazil’s Ministry of Health, issued 13 January 2016, citing the detection of Zika virus genome in 4 cases of congenital malformation in the state of Rio Grande do Norte. Two were miscarriages; 2 were infants who died within a day of birth.

  • US CDC confirmed another case of a mother in Hawaii who had recently travelled back from Brazil These cases add to evidence reported by the Ministry in December: the detection of Zika virus genome in the amniotic fluid of two pregnant women in Paraiba whose fetuses presented with microcephaly on ultrasound.

  • WHO is defining and supporting possible areas of research and calling on Member States to collect and share data on the outbreak with other countries’ Ministries of Health.

  • In addition, WHO is urging governments of affected countries to ensure that affected children are properly evaluated and monitored. There is no specific treatment for microcephaly.

Background on Zika virus

  • The virus was first identified in 1947 in rhesus monkeys in the Zika forest of Uganda, and was identified 5 years later in people in Uganda and the United Republic of Tanzania.

  • Zika virus disease is spread by the Aedes aegypti mosquito. They usually bite in the morning and late afternoon/evening hours. Where the mosquitoes get the virus is not known.

Prevention and Treatment

  • So far, no vaccine exists to prevent the disease,

  • WHO recommends prevention measures such as controlling the mosquito population. For example, containers that hold water should be emptied, covered or cleaned so that mosquitoes cannot use them to breed.

  • WHO further recommends limiting exposure to mosquitoes, for example by using insect repellent; wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets.

WHO Response

  • WHO is working with Ministries of Health in affected countries to improve the capacity of laboratories to detect the virus and monitor its spread.

  • WHO is coordinating with public health experts in Brazil, at the Pasteur Institute in France and at the Centers for Disease Control and Prevention in the United States to investigate the outbreak.

  • WHO advises that Member States base national-level recommendations on their assessment of evidence in their own countries and take into account possible risk factors and consequences as they relate to their own populations.