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Understanding the Zika Virus

The Zika virus disease and its related neurological complications no longer constitutes an international emergency, according to the World Health Organization (WHO). It’s best, however, to keep well informed about the epidemic, which remains a challenge that requires vigorous action.

If you’ve been following the news, you would know by now that the Zika virus is a mosquito-borne flavivirus that was first identified in monkeys in Uganda in 1947. In 1952, it was found in humans. The virus, which is transmitted primarily by the Aedes mosquito, is linked to deformations in newborn babies’ heads and brains.

Signs and symptoms

The time from exposure to symptoms, or the incubation period, takes a few days. The symptoms are similar to other arbovirus infections. There is usually fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache. These are mild, lasting for 2-7 days. There is no difference in symptoms between infected pregnant and non-pregnant women.


The Zika virus is primarily transmitted via:

  • Aedes genus, mainly Aedes aegypti in tropical regions. Aedes mosquitoes usually bite during the day, peaking during early morning and late afternoon/evening.
  • From mother to child.
  • Sexual transmission, both heterosexual and homosexual. The detection of Zika RNA in semen has been reported up to 188 days after the onset of the illness. There is no evidence at the present, however, that Zika can be transmitted through saliva during kissing.
  • The Centres for Disease Control reports cases of infection via blood transfusion in Brazil and French Polynesia, but none in the US to date.


Based on a systematic review of the literature as of May 30 2016, the WHO has concluded that infection during pregnancy may cause congenital Zika syndrome. It is a pattern of birth defects found among fetus and babies infected with the virus during pregnancy. These defects include:
a. Severe microcephaly
b. Decreased brain tissue with a specific pattern of brain damage
c. Damage to retina i.e. focal pigment mottling, atrophy, coloboma
d. Poor joint range of motions e.g. clubfoot
e. Hypertonia (too much muscle tone restricting body movement)
The virus is also a trigger of Guillain-Barré syndrome, where an individual’s immune system damages nerve cells and causes muscle weakness and sometimes, paralysis. This, however, is a rare syndrome.


Suspected based on symptoms and recent history of travel. A diagnosis can only be confirmed through laboratory tests on blood or other body fluids. The Zika virus has been detected in whole blood (serum and plasma), urine, cerebrospinal fluid, amniotic fluid, semen and saliva. There is accumulating evidence that the virus is present in urine and semen for longer periods than in whole blood or saliva.


The Zika virus disease is usually mild and requires no specific treatment. Take plenty of rest and fluids and medication for fever and pain relief. If symptoms worsen, seek medical advice. No vaccine is currently available.


Protecting yourself against mosquito bites is key to preventing Zika. You can do so by wearing light-coloured clothes that cover the body, installing physical barriers e.g. window screens, sleeping under mosquito nets and also using insect repellent containing DEET or icaridin. Do make sure you also clear mosquito breeding sites. Since Zika can be transmitted through sexual intercourse, both men and women need to be educated of the risks and complications of sexual transmission, and to make informed choices about whether and when to become pregnant. Women who do not wish to become pregnant should use contraception or abstain. Pregnant women should practice safe sex or abstain during pregnancy.

The WHO recommends practising safer sex or abstinence for a period of six months for both men and women returning from areas of active transmission.

Zika Worldwide

As of December 8, 2016, the Zika situation in the United States and Asia is as follows:

United States

  • Reported locally acquired mosquito-borne cases: 185
  • Reported travel-associated cases: 4,389
  • Reported laboratory acquired cases: 1

Total: 4,575

  • Sexually transmitted: 38
  • Guillain-Barré syndrome: 13
  • Life born infant with defects: 32
  • Pregnancy losses with birth defects: 5

The Centres for Disease Control statistics on Asia

Southeast Asian countries have an endemic level of Zika virus, a term for when a disease has been present in a region for many years. These countries comprise Brunei, Myanmar, Cambodia, Indonesia, Laos, Malaysia, Maldives, Philippines, Thailand, East Timor and Vietnam. CDC caution does not include countries with endemic. Risk level is unknown and likely lower than in areas where the Zika virus is newly introduced and spreading widely.

Malaysia: 3 reported cases, including a 58-year-old woman from Selangor, who is the mother of a female patient infected with the virus in Singapore. The second is a 27-year-old pregnant woman from Johor and the last from Sabah.

Singapore: 8 pregnant women among 329 infected since September 2016 but with no linked birth defects

Thailand: 33 new cases of Zika linked microcephaly since November 2016

The Philippines: 1 case in a pregnant woman (September)

Vietnam: 23 cases of Zika, 1 linked to microcephaly (November)

Hong Kong: 2 imported cases (November)

Article by:
Dr Ian Ping Wee Yen

Consultant Paediatrician