Zika virus (ZIKV) is a virus first detected in East Africa that is transmitted by mosquitoes. While Zika infection is mostly harmless to healthy adults and usually causes no or mild symptoms, infection during pregnancy can cause severe damage to the fetus.
Transmission by mosquitoes
The virus is transmitted mainly by the yellow fever mosquito, also known as the Egyptian tiger mosquito (Aedes aegypti), which is found in all tropical and some subtropical countries. In addition, it is suspected that other mosquito species of the genus Aedes, such as the Asian tiger mosquito, can also infect humans with the virus. Isolated cases of sexual transmission of Zika virus or infection during childbirth (from mother to child) have also been described. The disease has also occurred as a result of blood transfusions. It is not yet known whether infection is possible through urine or saliva.
Symptoms of Zika infection
Zika virus infection causes symptoms similar to those of other mosquito-borne diseases, such as dengue fever. However, Zika infections are much milder in comparison. Signs include:
- Fever (hence the name “Zika fever“).
- Nodular-spotted skin rash
- Joint pain
- Conjunctivitis (inflammation of the conjunctiva)
- Less frequently: muscle pain, headache and vomiting.
The incubation period, the time from infection with the virus to the appearance of symptoms, is usually three to twelve days. The symptoms usually last a few days to a week. It is assumed that in about four out of five infected persons no symptoms occur at all. In most cases, the infection heals without further consequences.
Treatment of Zika infection
Since there is currently no specific therapy for the Zika virus, only treatment of the symptoms is given. Pain relievers and fever-reducing medications are usually administered. Rest and drinking adequate amounts of fluids are also recommended.
Triggers of secondary diseases?
Zika virus is usually harmless to a healthy adult. However, it is considered likely that the virus can trigger Guillain-Barré syndrome – a nerve disease that causes paralysis. In addition, there is speculation about a link to the development of other secondary diseases, such as spinal meningitis or meningitis, which have been observed in isolated cases after Zika infection.
Zika infection in pregnancy
It is considered proven that Zika infection in the first trimester of pregnancy can cause microcephaly, a malformation of the brain, in the unborn baby. An increasing number of microcephaly cases in newborns has been observed in high-risk areas. However, it is still unclear how often infection with the virus actually results in microcephaly in babies. The affected infants are born with a significantly smaller head and a brain that is usually underdeveloped.
Protection from infection
To date, no vaccination against the Zika virus exists. As a protective measure, it is therefore recommended – especially for pregnant women – to avoid the risk regions if possible, as well as general methods to ward off mosquitoes. Since sexual transmission is probably also possible, the use of condoms is also recommended. Those who have survived a Zika infection are subsequently considered immune to re-infection with the virus.
Origin and distribution of the Zika virus
The virus was first isolated in 1947 in a rhesus monkey in the Zika Forest in Uganda, which gave it its name. There are two lineages of Zika virus: the African lineage and the Asian lineage. The virus belongs to the genus Flavivirus, to which various viruses transmitted by ticks or mosquitoes are assigned. These include the viruses that cause yellow fever, TBE, and dengue fever. In humans, Zika virus was first detected in Uganda and Tanzania in 1952. Until 2007, human infections occurred exclusively in Africa and Southeast Asia. Since the beginning of 2015, the virus has been observed more frequently in Central and South America, especially in Brazil and Colombia. Travelers have also spread the Zika virus to other areas, resulting in cases of Zika fever among travelers returning to many countries.However, there are no known cases of transmission in Germany.
