Zika virus, a new infectious teratogen? Alarming observations from Brazil
Zika virus and microcephaly in Brazil
The Zika virus epidemic started in Brazil in May 2015, and by end of November more than 1,200 cases of microcephaly have been reported in Brazil during 2015, reaching a prevalence of 99.7:100,000 in live born infants, compared to the background annual prevalence of 5.5:100,000.
The Zika virus disease is a mosquito-borne (Aedes species) viral disease caused by Zika virus. The main symptoms of the disease include low-grade fever, transient arthralgia mainly in the small joints of hands and feet, and maculo-papular rash often spreading from the face to the body. Other general flue-like symptoms may be present, but symptom-free infection is common and it has been estimated that only one out of four infected experience some symptoms.
The disease has been previously endemic in tropical Africa and South-East Asia, and during the last years also in the South Pacific regions. This is the first year when the disease has been reported in South America.
WHO and European Centre for Disease Prevention and Control (ECDC) have published an alert about the possible association between maternal Zika virus infection and offspring microcephaly (www.ecdc.europa.eu).
The prevalence of microcephaly has increased 20-fold compared to the prevalence prior to epidemic. The causal association has not been confirmed but is considered highly probable. Microcephaly is a severe congenital condition, resulting in intellectual disability and neurological impairment. Fetal adverse effects associated with Zika virus infection have not been reported previously.
There is no vaccine or specific treatment for Zika virus infection. Travelers visiting affected areas, particularly pregnant women, are advised to take effective protective measures to prevent mosquito bites all day round as the virus is transmitted by a daytime mosquito. Official recommendations concerning traveling to endemic areas have as yet not been given.