Zika
The virus was first discovered in Uganda in 1947 in rhesus monkeys living in a forest called Zika. Until recently, it was detected only in Africa and Asia, as well as in the island states of the Pacific region. However, in May 2015, Zika was diagnosed with Brazilians.
There are two versions explaining the appearance of the virus on the South American continent. According to one of them, it could be imported from Africa during the World Cup in Brazil in 2014. Another hypothesis is that the virus entered the largest country in South America from Micronesia.
Now Zika cases have been reported in more than 20 countries in Latin America and the Caribbean, as well as in the United States and several European countries.
Why is the virus dangerous?
Microcephaly. In November 2015, the Brazilian Ministry of Health confirmed that infection with the virus during pregnancy causes the baby to develop microcephaly – a birth defect that consists of a significant reduction in the size of the skull and is accompanied by mental retardation, neurotic disorders, hearing and visual impairment. The country’s authorities are recording an increase in the birth of children with microcephaly. According to the latest data, from October 22 (when the authorities began to keep statistics) to January 23 in the largest South American country, 4180 possible cases of microcephaly in infants were recorded, which is more than 25 times higher than in 2014, when the number of sick children did not exceed 150.
A causal relationship between the Zika virus, malformations, and neurological syndromes has not yet been established, but there are strong suspicions about its existence.
Guillain-Barré Syndrome. Some researchers believe that the Zika virus is dangerous not only for children but also for adults. It is believed that fever can result in the development of a rare autoimmune disease – Guillain-Barré syndrome. It is characterized by paresis (partial paralysis) of the lower extremities, which after a few days or even hours spreads to the hands, and then to other body muscles. The main danger is that it can affect the respiratory system, in which case the person runs the risk of dying from oxygen lack. In addition, in some cases, Guillain-Barré syndrome causes some human muscles to remain paralyzed for life.
Lack of vaccine. The situation around the virus is exacerbated by the fact that there is no vaccine for it. According to experts, the corresponding drugs will appear no earlier than in 2 to 3 years.
Virus transmission routes
The Zika virus carrier is the Aedes aegypti mosquito, better known as the aedes albopictus. It is also a distributor of dengue and chikungunya viruses. A favorable environment for the reproduction of these insects is created, in particular, by landfills and open water tanks. Aedes aegypti are present in most countries with tropical and subtropical climates.
Currently, employees of the Brazilian Science Foundation is testing the hypothesis that other types of mosquitoes, such as Culex, can be carriers of Zika virus. This assumption is based on the fact that a fever epidemic was recorded in Micronesia, where Aedes aegypti do not inhabit.
In addition, there is evidence that the virus can be transmitted from person to person during unprotected sex.
Transmission from mother to fetus is not excluded. However, WHO emphasizes that “evidence of Zika’s transmission during pregnancy or from mother to child is limited.” Research is currently underway to collect more evidence regarding perinatal transmission and to better understand how the virus affects infants. So far, there is no evidence that Zika can be transmitted through breast milk.
Symptoms
The Zika virus has the same symptoms as dengue and chikungunya fever:
- fever;
- headaches;
- muscle aches;
- weakness;
- skin rash;
- conjunctivitis.
In some cases, the disease is accompanied by nausea and vomiting, as well as pain in the stomach. However, some experts point to the fact that Zika fever can occur without pronounced symptoms. In this regard, it is very difficult to establish the exact number of cases: many patients after infection with the virus feel only mild malaise and do not go to the doctors.
The disease lasts about a week (from 2 to 7 days). The incubation period is from 3 to 12 days.
After recovery, the virus persists for more than 2 weeks in seminal fluid.
Distribution geography
According to WHO forecasts, the Zika virus can spread widely in America, affecting all countries except Canada and the mainland of Chile.