About the Zika Virus

Recently there has been a significant amount of news coverage on the Zika virus.

What is Zika Virus and what are your risks?

Zika virus infection is generally a non severe febrile viral illness transmitted by mosquitoes. Zika should be considered in people who have recently travelled overseas. There have been recent outbreaks in Central and South America, particularly Brazil. These have raised concerns that infection with Zika virus in pregnant women might cause certain congenital abnormalities including microcephaly (small brain associated with mental retardation).

The knowledge about any causal link between Zika virus and these outcomes is evolving and further studies are required. Until more is known, specific travel precautions are recommended for pregnant women or women planning pregnancy.

All travellers should take steps to avoid mosquito bites in order to prevent Zika virus infection and other mosquito-borne diseases such as dengue, malaria and chikungunya.

Until more is known about Zika virus transmission in pregnancy and the association with adverse foetal outcomes, pregnant women are advised to consider postponing travel to any area where Zika virus transmission is ongoing. Pregnant women who do decide to travel to one of these areas are advised to consult with a doctor first and strictly follow mosquito bite prevention measures during their trip. Women trying to become pregnant are advised to consult with a doctor before travelling and strictly follow mosquito bite prevention measures.

Zika virus is a flavivirus, closely related to dengue. It is transmitted to humans primarily through the bite of certain infected Aedes species mosquitoes. Aedes aegypti mosquitoes are commonly found in tropical and sub-tropical regions around the world including north Queensland and some areas in central Queensland. Another similar mosquito, Aedes albopictus, also has the potential to transmit Zika virus, but in Australia is only found in the Torres Strait. These mosquito vectors typically breed in domestic water-holding containers; they are daytime biters and feed both indoors and outdoors near dwellings.

Outbreaks of Zika virus have previously been reported in tropical Africa, Southeast Asia, and the Pacific Islands.

What are the Symptoms of Zika virus infection?

Approximately one person in five who becomes infected with Zika is likely to have symptoms. For cases with a clinical illness, symptoms may include:

  • Low-grade fever (between 37.8°C and 38.5°C)
  • Arthralgia (joint pain), notably of small joints of hands and feet, with possible swollen joints
  • Myalgia (muscle pain)
  • Headache,
  • Conjunctivitis
  • Rash
  • More rarely observed symptoms include digestive problems (abdominal pain, diarrhoea, and constipation), mucous membrane ulcerations and itchiness.

Zika virus infection generally causes a non severe disease (with the possible exception of the effects to the foetus in pregnant women, as discussed below). As Zika infection may cause a rash that could be confused with other diseases such as measles or dengue, these more serious diseases need to be ruled out.

Diagnosis of Zika Infection

This will firstly be by exclusion, based on symptoms, travel history and exclusion of other diseases including measles and dengue. The incubation period is typically 3–12 days. There is no specific therapy for Zika virus infection and acute symptoms typically resolve within 4-7 days. There is a risk of transmission of Zika from infected returning travellers in areas of North Queensland where a suitable vector, the mosquito Aedes aegypti.

Women who are pregnant and travelled to areas where there was ongoing Zika virus transmission at the time of travel, and who suffered an illness that is suspected to be Zika, are advised to see a doctor.

Prevention of Zika Infection

All travellers are advised to take the following mosquito bite prevention measures when travelling to areas currently affected by Zika virus or wherever mosquito borne diseases are present. These precautions are necessary in the daytime as well as night time.

  • Wear long-sleeved shirts and long pants;
  • Use insect repellents containing DEET or picaridin. Always use as directed;
  • Insect repellents containing DEET or picaridin, are safe for pregnant and breastfeeding women and children older than 2 months when used according to the product label;
  • If you use both sunscreen and insect repellent, apply the sunscreen first and then the repellent;
  • Use permethrin-treated clothing and gear (such as boots, pants, socks, and tents); • Use bed nets as necessary;
  • Stay and sleep in screened-in or air-conditioned rooms.

Diagnosis of Zika Infection

Preliminary diagnosis is based on the patient’s clinical features, places and dates of travel, and activities.

Laboratory diagnosis is generally accomplished by testing serum or plasma to detect virus, viral nucleic acid, or virus-specific immunoglobulin M and neutralizing antibodies. Laboratory testing

  • Zika virus testing is performed at state public health laboratories in Australia. If Zika is suspected, your doctor will discuss testing with their local pathology provider. Testing for Zika infection includes IgM, IgG and PCR (positive only in early infection).
  • Acute serum (taken within 5 days of symptom onset) and convalescent serum (2–3 weeks later) should be taken. The two samples are important to rule out false positive tests due to cross reactivity with similar viruses such as Dengue
  • Provide overseas travel details and clinical history including the onset day. Onset date is extremely important to ensure that the most appropriate test is performed.

Treatment of Zika Virus

No specific antiviral treatment is available for Zika virus infection. Treatment is generally supportive and can include rest, fluids, and use of analgesics and antipyretics. People infected with Zika virus should be protected from further mosquito exposure during the first few days of illness to prevent other mosquitoes from becoming infected and reduce the risk of local transmission.

Please contact us if you want to discuss this with one of our doctors.