In May 2015, Brazil announced an outbreak of the mosquito-borne flavivirus Zika virus (ZIKV). Since then the virus has spread widely with transmission detected in 40 countries/territories in the past 9 months. The UK defines areas with active ZIKV transmission according to the ECDC country list. Brazil estimates that between 500 000 to 1.5 million cases have occurred in the last 9 months with Colombia estimating 31 000 cases in 5 months. To date, 10 confirmed cases of ZIKV infection have been reported in UK travellers, 9 of which have been linked to this outbreak.
ZIKV, after an incubation of 2-12 days, produces a mild clinical illness, similar to dengue fever that resolves in 4–7 days. Symptoms may include: fever, headache, conjunctivitis, rash, myalgia and arthralgia. There is no specific treatment, or vaccine and management is supportive only.
ZIKV Infection and Microcephaly
Concern has been raised by a large increase in the number of reported cases of microcephaly and central nervous system (CNS) malformations in neonates and fetuses in Brazil and French Polynesia that coincide with ZIKV outbreaks in these countries. Investigations by the World Health Organisation and local health authorities are ongoing to establish if ZIKV in pregnancy is the underlying cause of these congenital anomalies. Although not proven, it seems increasingly likely that the increase in microcephaly in Brazil may be associated with the ongoing ZIKV outbreak.
Guillain-Barré Syndrome (GBS) has been increasingly reported from some countries currently experiencing an outbreak of ZIKV; GBS is postulated as a rare sequela to ZIKV and investigations are ongoing to establish a causal link.
ZIKV has been detected in semen two months after clinical symptoms of ZIKV; a small, but growing number of probable sexually transmitted cases of ZIKV infection (male to female) have been reported.
Advice for Travellers to ZIKV Affected Countries
- Mosquito bite avoidance is strongly recommended.
- Advised to seek travel advice from a healthcare provider at least 6-8 weeks in advance of travel, but particularly important if pregnant or planning pregnancy.
- Strongly advised not to travel without adequate insurance – pregnant women should check with their travel insurance company that they are covered under the policy.
Women who are Pregnant
- Advised to postpone non-essential travel to countries with active ZIKV transmission until the proposed link between ZIKV and adverse pregnancy outcomes has been fully clarified.
- If travel is essential, women should understand the risks in order to make a fully informed decision.
- During travel, strict bite avoidance is essential. The use of barrier methods to prevent potential sexual transmission of ZIKV from a male partner during travel and throughout the pregnancy is advised.
- On return, an early obstetric review is recommended even if well.