Zika Virus infection
29 January 2016
Zika virus infection outbreaks have been reported recently in the Pacific and Central and South America. The virus is also known to occur in south east Asia and Africa. Recent outbreaks have been associated with a dramatic increase in the numbers of infants with severe birth defects including microcephaly, and other poor pregnancy outcomes, particularly in Brazil, and investigations are underway to determine whether there is a causal link with Zika virus infection in pregnancy. An increase in autoimmune and neurological diseases during an outbreak in French Polynesia is also being investigated. Zika virus is not generally transmitted from person to person other than maternal-fetal transmission, though sexual transmission is considered possible.
Zika virus is an arthropod borne virus transmitted through the bite of Aedes mosquitoes, primarily A. aegypti but also by A. albopictus. Neither species occurs in South Australia though A. aegypti is present in parts of north and central Queensland.
The incubation period is typically 3-12 days. Zika virus infection is asymptomatic in around 80% of people. Symptoms include acute fever (usually low grade: 37.8-38.5°C), maculopapular rash, arthralgia (usually of small joints of hands and feet, swelling may occur), non-purulent conjunctivitis, and retro-orbital headache.
Travellers to areas where Zika virus transmission is occurring are being advised to:
- avoid mosquito bites, particularly if pregnant, see Fight the Bite
- if pregnant (any trimester) consider postponing travel until more is known about pregnancy and Zika virus infection
- visit their GP if symptoms consistent with Zika virus infection occur.
Doctors are asked to consider Zika virus infection in patients with:
- history of travel, within 14 days of illness onset, to areas with current or recent outbreaks or transmission of Zika virus, AND
- symptoms consistent with Zika virus infection
Management of suspected cases:
- Notify the Communicable Disease Control Branch on 1300 232 272. Zika virus infection is a notifiable condition in South Australia as Arbovirus (not listed elsewhere).
- Discuss testing with SA Pathology. If testing is indicated, take blood for Zika virus PCR (note that period of viraemia is less than 7 days) AND paired serum for IgM and IgG for Zika virus – acute serum within 5 days of symptoms onset if possible AND convalescent specimen 2-3 weeks later. Only paired serum samples will be sent interstate for parallel testing.
- Exclude other clinically similar diseases such as dengue, malaria, parvovirus and alphavirus (Ross River, Chikungunya) infection, and measles and rubella if there is no history of vaccination.
- Recommend symptomatic treatment such as rest, fluids, analgesics and antipyretics. Do not use aspirin and other NSAIDs until dengue has been excluded. There is no specific treatment for Zika virus infection. Acute symptoms usually resolved within 4-7 days.
- Suspected or confirmed cases of Zika virus infection should avoid travel to Queensland. Screening of asymptomatic pregnant women is not recommended in the absence of fetal microcephaly or intracranial calcifications.
For further information see: Zika virus – information for clinicians and public health practitioners and information about management of pregnant women.