Zika Virus – WHO Declares Public Health Emergency

Zika is a vector-borne virus transmitted by the same species of mosquito that spreads dengue fever, chikungunya, and yellow fever. An alarming increase in infections in South and Central America is giving scientists serious cause for concern and on February 1, 2016, the World Health Organization (WHO) declared it a public health emergency. Zika usually only causes mild illness, but a link between the virus and congenital birth defects and neurological syndromes is strongly suspected. There is no vaccine or cure and the WHO says that the best form of protection is prevention of mosquito bites.

Zika Virus: The Facts

The Zika virus was first isolated in 1947 from a monkey in the Zika forest of Uganda. For decades, the disease slumbered, affecting mainly monkeys. In humans, Zika occasionally caused a mild illness of low concern. The first documented outbreak of Zika was recorded in the Pacific islands in 2007, and from 2013-2014, four additional Pacific island nations reported large Zika outbreaks. In 2015, the virus was detected in the Americas, where it is now spreading explosively. By the end of January 2016, cases had been reported in 23 countries and territories in the region.


It is transmitted by the Aedes genus of mosquito: Aedes aegypti mosquitoes are the primary carriers of Zika virus, but Aedes albopictus mosquitoes, known as Asian tiger mosquitoes, are also potential transmitters of the disease. Unlike most other species, Aedes mosquitoes bite during the daytime, as well as late afternoon and evening.


The virus is currently known to circulate in Africa, the Americas, Asia and the Pacific. The World Health Organization has issued a statement anticipating the spread of Zika across all parts of the Americas where Aedes is present, except Canada and continental Chile.


Although symptoms are usually mild, potentially more serious links between neurological syndromes and microcephaly in infants born to women infected with Zika virus during pregnancy are strongly suspected and are being investigated by health authorities.


Global map of the predicted distribution of Aedes aegypti. The map depicts the probability of occurance (from 0 blue to 1 red) at a spatial resolution of 5 km x 5 km.
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Health experts estimate the incubation period of Zika virus infections to be a few days. Sufferers usually experience no or very mild symptoms such as mild fever, rashes, conjunctivitis, muscle and joint pain, and headaches. The symptoms normally last for 2-7 days and require no specific treatment. If symptoms worsen, medical care and advice should be sought. Suspected links between neurological and auto-immune complications and Zika virus, as well as an increase in babies born with microcephaly, are also being investigated, though not yet scientifically proven.


As there is no vaccine to prevent the Zika virus, the challenge is to prevent its spread to humans. According to the WHO, the best prevention is to combat the mosquitoes and prevent them from biting. This includes reducing mosquito populations by removing breeding sites and reducing contact between mosquitoes and people.


During outbreaks, health authorities may carry out spraying of insecticides and larvicides may be used to treat relatively large water containers. It is also important to remove potential breeding sites. All types of containers that hold water, such as buckets, flower pots, drink cans or discarded tires, should be removed, emptied or covered.

Old big earthenware jar brimmed with water
Old road tires stacked on grass land

For personal protection in affected areas, the WHO recommends using insect repellent; wearing light colored clothes that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets.


Women in affected areas who are pregnant or planning to become pregnant should take extra care to protect themselves from mosquito bites.


Travellers should stay informed about Zika virus and other mosquito-borne diseases and consult the WHO website, or local health and travel authorities if they are concerned.


BASF recommends householders and businesses who are concerned about mosquito-control around their property to contact a pest management professional or their local health authorities for advice.

Source: World Health Organization