Zika virus infection (1,2)
- Zika virus is part of the flavivirus family, which includes dengue virus and yellow fever virus
- Zika virus infection is spread by the Aedes aegypti mosquito
- occurs predominantly in tropical and sub-tropical areas
- this mosquito is most active during the day, especially during mid-morning and later afternoon to dusk, but it can also bite at night in well-lit areas
- Aedes aegypti mosquitoes, and other proposed mosquito species that may be capable of transmitting Zika virus, are not found in the UK
- estimated that the majority of those infected with Zika virus do not develop symptoms or have subclinical illness
- estimated incubation period is up to 14 days
- infected individuals who do develop symptoms typically have a mild illness that is similar to uncomplicated dengue virus infection: a mild illness lasting two to seven days, consisting of a combination of fever, joint pain, rash, conjunctivitis/red eyes, headache, muscle pain and eye pain
- most symptomatic cases are short-lived and will resolve spontaneously
- increasing evidence that infection in pregnancy may be associated with fetal microcephaly and other central nervous system abnormalities
- Zika virus infection has been linked with Guillain-Barre syndrome.
General travel advice for patients
- all travellers to areas with active Zika virus transmission should practise mosquito bite avoidance measures, both during daytime and night time hours (but especially during mid-morning and late afternoon to dusk, when the mosquito that transmits Zika virus is most active)
- pregnant women planning to travel should consider avoiding travel to areas with active Zika transmission
- if travel is unavoidable, or they live in areas where active Zika transmission is reported
- they should take scrupulous insect bite avoidance measures, both during daytime and night time hours (but especially during mid-morning and late afternoon to dusk, when the mosquito that transmits Zika virus is most active)
- all pregnant women who have recently travelled to a country where active Zika transmission is reported should notify their primary care clinician, obstetrician or midwife
- an application of insect repellent containing 50% DEET (N,N-diethyl-m-toluamide) will repel mosquitoes for approximately 12 hours
- repellents containing 50% DEET can be used by pregnant women, but higher concentrations should not be used
- when both sunscreen and DEET are required, DEET should be applied after the sunscreen. Sunscreen with a 30 to 50 SPF rating should be applied to compensate for DEET-induced reduction in SPF
- use of DEET is not recommended for infants less than two months of age
Preventing potential sexual transmission of Zika virus (1,2)
Rsk of sexual transmission of Zika virus is thought to be very low, but sexual transmission has been reported
if a female partner is at risk of getting pregnant, or is already pregnant, condom use is advised for a male partner arriving from an affected area for the following durations:
- 28 days after his return from a Zika virus transmission area if he has not had any symptoms compatible with Zika virus infection
- six months following recovery if a clinical illness compatible with Zika virus infection or laboratory-confirmed Zika virus infection was reported (1,2)
This is a precautionary approach and may be revised as more information becomes available. 28 days represents an estimated 14 day incubation period plus an estimated 14 day period of viraemia (1).
Recommendations for women planning pregnancy who have travelled to or arrived from an area with active Zika virus transmission (1,2)
- after a woman leaves an area with active Zika virus transmission, it is recommended that she should not try to conceive for 28 days (this covers an estimated 14 day incubation period plus an estimated 14 day period of viraemia).
Testing pregnant women for infection with Zika virus
- only pregnant women with a history of travel to an area with active Zika virus transmission and who present with current symptoms consistent with Zika infection that began during or within 2 weeks of travel should be tested
- testing should include investigation for other travel associated infections (such as malaria, dengue fever and chikungunya) as well as Zika.
Monitoring if pregnant woman positive for Zika virus
- pregnant woman who tests positive for Zika virus infection will be referred to a Fetal Medicine service for further assessment - this may include regular (4-weekly) fetal ultrasound scans to monitor fetal growth and consideration of fetal MRI.
Reference:
- Public Health England (February 2016). Zika virus infection: guidance for primary care.
- Royal College of Obstetricians and Gynaecologists (February 2016). Q&As on Zika and pregnancy.