DISTRIBUTION
The most at-risk areas are the tropical zones and the Mediterranean region, but the virus can appear anywhere, where Aedes mosquitoes can survive. In Brazil, it emerged in the spring of 2015 and spread rapidly throughout the year to several other South and Central American countries. In Europe, Zika virus cases are few and currently imported, however their number is expected to rise due to travel to the most affected regions. Since the virus has been shown to transmit sexually, there is also a non-negligible chance that Zika virus could spread locally.
AFFECTED HOST SPECIES
The full range of vertebrate hosts is not completely known. Most frequently, infections have been reported in humans and non-human primates, but some studies suggest that small mammals (e.g., rodents) can also be infected.
TRANSMISSION AND VECTORS
Zika is primarily transmitted by mosquitoes of the genus Aedes, with the most important vectors being invasive species such as the Asian tiger mosquito (Aedes albopictus). It is not yet known whether other local mosquito species can transmit the virus, but no such cases have been observed in temperate countries. The virus can also be transmitted sexually.
SYMPTOMS
In humans, the disease is usually relatively mild. After a few days of incubation, roughly one-fifth of infected individuals develop general febrile symptoms (fatigue, weakness, nausea), skin rashes, and muscle or joint pain. The illness is generally self-limiting, with symptoms resolving within a few days. Severe symptoms (e.g., neurological complications) are rare. Based on symptoms alone, viral infections cannot be definitively distinguished, so laboratory tests are needed for an accurate diagnosis. Following Zika outbreaks, there was a significant increase in the number of children born with microcephaly, for which the virus was responsible.
TREATMENT AND PREVENTION
Currently, there is no vaccine available against Zika virus. The most reliable protection is to prevent mosquito bites in affected areas. There is no specific treatment for the disease; symptom relief and fever management are possible if needed. Individuals who recover from the infection become virus-free and immune, so fetuses conceived after recovery are not expected to be affected.