Zika virus outbreak
Zika virus was first identified in rhesus monkeys in the Zika forest near the shore of Lake Victoria in Uganda in 1947.
On 18 April 1947, Researchers who are studying yellow fever virus, found a rhesus money identified as 766 ran a fever of 39.7°C, about 2°C higher than normal. The monkey was living in a cage on a platform built into the tree canopy in the Zika forest. The Zika forest is 1.5 km long and is adjacent to an arm of Lake Victoria in Uganda. Investigators took blood sample from the rhesus money 766 and injected it into the brains of Swiss albino mice. The mice showed signs of sickness after 10 days, and the researchers harvested their brains, from which they isolated a filterable transmissible agent. Tests of the animal’s blood turned up an unknown virus.
In January 1948, the same researchers trapped mosquitoes from these canopy platforms. They were able to isolate yellow fever virus from the mosquitoes. Others had shown that one of these species they caught, Aedes africanus, shuttled the yellow fever virus, so the investigators put 86 of the insects in a refrigerator to “render them inactive” and then ground them up in a blood-saline solution, which they again injected into the brains of mice. The animals “appeared inactive” after 7 days, and tests showed they harbored the same transmissible agent that had sickened Rhesus 766. The researchers called their “hitherto unrecorded virus” Zika.
The Zika virus was later identified in humans in Uganda and the United Republic of Tanzania in 1952.
For many years, sporadic cases of Zika virus in humans were detected in Africa and southern Asia. Some cases of Zika virus were found in Asia in 1950 and in Pakistan in 1977-78.
In recent times, the first outbreak of Zika virus was identified in 2007, in Yap. Since 2013, cases and outbreaks of the disease have been reported from the Western Pacific, the Americas and Africa.
Zika virus is relatively unknown till 2015. It originated in Africa and made its way to a series of tiny islands in Micronesia. Then it bounced through the Pacific Ocean to Easter Island, off the coast of Chile. From there, it was on to Brazil. The recent outbreak of Zika virus began in April 2015 in Brazil. It subsequently spread to other countries in South America, Central America and the Caribbean. The World Health Organization predicts that the Zika virus could spread the majority of the Americas by the end of 2016. WHO estimates that Zika virus could affect 4 million people by end of 2016. As of February 2016, the virus has spread in more than 20 countries since its April 2015 outbreak.
The Zika virus is mainly spread by the Aedes aegypti mosquito and Aedes albopictus mosquito. The Aedes aegypti mosquito is commonly found throughout the the tropical and subtropical Americas. The Aedes albopictus mosquito has been widespread up to the Great Lakes area of the United States.
The Zika virus doesn't seem to harm most of its victims. However, there is increasing evidence that it causes serious damage to the brains of fetuses and in rare causes, neurological problems in adults.
In early 2016, a number of countries have issued travel warnings.
The virus was detected in the United States, Denmark and Portugal.
Local transmission of Zika virus
Local transmission of Zika virus is reported in the following countries. Local transmission means that mosquitoes in the area have been infected with Zika virus, spreading it to people.
- Commonwealth of Puerto Rico, US territory
- Costa Rica
- Dominican Republic
- El Salvador
- French Guiana
- Saint Martin
- U.S. Virgin Islands
- Zika virus outbreak in Brazil in May 2015
- 1.5 million people affected in over 20 countries, as of January 2016
- The virus was recently found in at least 24 countries. At least 30 cases were reported in the United States, as of February 1, 2016