Zika fever is a mosquito-borne viral disease caused by Zika virus (ZIKV), consisting of mild fever, rash (mostly maculo-papular), headaches, arthralgia, myalgia, asthenia, and non-purulent conjunctivitis, occurring about two to seven days after the mosquito vector bite.
One out of four people may develop symptoms, but in those who are affected the disease is usually mild with symptoms that can last between two and seven days. Its clinical manifestation is often similar to dengue, also a mosquito-borne illness.
The virus was isolated for the first time in 1947 in the Zika forest in Uganda. Since then, it has remained mainly in Africa, with small and sporadic outbreaks in Asia. In 2007, a major epidemic was reported on the island of Yap (Micronesia), where nearly 75% of the population was infected.
- In 2007, a major epidemic was reported on the island of Yap (Micronesia), where nearly 75% of the population was infected.
- On 3 March 2014, Chile notified PAHO/WHO of autochthonous transmission of Zika virus on Easter Island, where the virus continued to be detected until June 2014.
- In May 2015, the public health authorities of Brazil confirmed the transmission of Zika virus in the country's northeast.
- Since October 2015, other countries and territories of the Americas have reported the presence of the virus.
- Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes, which bite during the day.
- Symptoms are generally mild and include fever, rash, conjunctivitis, muscle and joint pain, malaise or headache. Symptoms typically last for 2–7 days. Most people with Zika virus infection do not develop symptoms.
- Zika virus infection during pregnancy can cause infants to be born with microcephaly and other congenital malformations, known as congenital Zika syndrome. Infection with Zika virus is also associated with other complications of pregnancy including preterm birth and miscarriage.
- An increased risk of neurologic complications is associated with Zika virus infection in adults and children, including Guillain-Barré syndrome, neuropathy and myelitis.
- See the WHO fact sheet on Zika virus
About Aedes aegypti...
Aedes aegypti is the vector that presents the greatest risk of arbovirus transmission in the Americas and is present in almost all countries of the hemisphere (except Canada and continental Chile). It is a domestic mosquito (that lives in and near houses) that reproduces in any artificial or natural container that contains water.
The mosquito can complete its life cycle, from the egg to the adult, in 7-10 days; adult mosquitoes usually live 4 to 6 weeks. The female Aedes aegypti is responsible for the transmission of diseases because she needs human blood for the development of her eggs and for her metabolism. The male does not feed on blood.
The mosquito is most active early in the morning and at dusk, so these are the periods of greatest risk of bites. However, females, who need to continue feeding, will seek a source of blood at other times. The female Aedes aegypti feeds every 3-4 days; however, if they cannot draw enough blood, they continue feeding each moment they can.
Aedes aegypti prefers to lay its eggs in artificial containers that contain water (drums, barrels and tires, mainly) in and around homes, schools and workplaces. Aedes aegypti eggs can withstand dry environmental conditions for more than a year: in fact, this is one of the most important strategies that the species uses to survive and spread.
To eliminate mosquitoes, the following actions are recommended: avoid collecting water in open-air containers (pots, bottles or other containers that can collect water) so that they do not become breeding sites for mosquitoes; adequately cover water tanks and reservoirs to keep mosquitoes away; avoid accumulating garbage, throwing garbage in closed plastic bags.
PAHO/WHO is working actively with the countries of the Americas to develop or maintain their ability to detect and confirm cases of Zika virus infection, treat people affected by the disease, and implement effective strategies to reduce the presence of the mosquito and minimize the likelihood of an outbreak. PAHO/WHO's support has three main pillars:
- Controlling the vector by working actively with national authorities, partners and communities to eliminate mosquito populations.
- Building the capacity of laboratories to detect the virus in a timely fashion (together with other collaborating centers and strategic partners).
- Monitoring the geographic expansion of the virus and the emergence of complications and serious cases through surveillance of events and country reporting through the International Health Regulations channel.
- Preparing recommendations for the clinical care and monitoring of persons with Zika virus infection, in collaboration with professional associations and experts from the countries.
- Advising on risk communication to respond to the introduction of the virus in the country.
- Helping countries to buy insecticides and larvicides for vector control, medicines for treating patients with complications; and laboratory supplies for diagnostic, through PAHO Strategic Fund.
For these three pillars, PAHO/WHO is supporting initiatives by health authorities and academic and research institutions aimed at learning more about the characteristics of the virus, its impact on health, and the possible consequences of infection.