World Facts

What Is the Zika Virus? - Diseases of the World

Reaching pandemic levels in Central and South America, Zika is harmless to adults but potentially disastrous to infants.



First noticed in the African country of Uganda during the 1940s, the Zika virus is a disease that has since spread to South and Central America. It is related to similar diseases of the Flavivirus genus and overall Flaviviridae family, such as dengue fever, yellow fever, and the West Nile virus. For most adults, the symptoms and effects of Zika are fairly minimal. Indeed, in most cases there are no symptoms whatsoever, and only one in five people infected with the Zika virus actually develop the Zika fever (which is also known as Zika disease, or simply Zika). In cases where the Zika fever occurs, symptoms may include fever, rash, joint and muscle pain, reddened eyes (conjunctivitis), and headaches. The virus and disease tend to last between a few days to one week.


The Zika disease can only be transmitted via blood, so humans are generally not contagious to others and the disease cannot be transmitted easily between two people, though significantly it may be possible for the disease to be transmitted from a pregnant mother to her child. The disease is most often transmitted to humans through mosquitos, who will become infected with Zika if they suck the blood of a body infected with the virus and can then infect other humans. Indeed, mosquitos are the primary method for the disease’s transmission, not unlike its cousins dengue and yellow fever. Mosquito transmission is how the disease spread from its origins in Uganda and nearby countries.


Although the possibility of death as a result of developed Zika is incredibly rare among most adults infected with the disease, the real major concern regarding Zika is its effects on pregnant women and their newborn babies. Although most diseases within its family are dangerous for causing severe brain swelling (encephalitis), Zika is unique in that it seems to cause the brains of infected newborns and infants to shrink (microcephaly). Infected infants suffering from microcephaly caused by Zika could grow up with various neurological disorders, malformations, and paralysis as a result of shrunken brains, and these effects can also ultimately result in death.


As recently as 2014, mosquitos carrying Zika moved eastwards from the virus’ origins in equatorial Africa and Asia, managing to cross the Pacific Ocean via various Polynesian islands before eventually reaching Central and South America. The virus has since been regarded as a pandemic, with between three and four million cases estimated within the past twelve months. These numbers can be potentially even higher, as the vast majority of adults infected with Zika develop no symptoms and never learn that they are carrying the disease. These infections are occurring almost entirely within Latin America and the Caribbean, with cases reported as far south as Brazil and as far north as Mexico. The mosquito species capable of transmitting the disease (Aedes aegypti) has an even wider range, spreading from Argentina to the southern United States. No cases of local Zika transmission within the continental US have been reported as of yet, though cases of travelers returning to the country with Zika have occurred and local transmission have already been reported in both Puerto Rico and the US Virgin Islands.


Perhaps the biggest concern regarding Zika and its potentially serious effects on babies and infants is the fact that there is no known cure or vaccine for the virus. Scientists in the United States working on attempts to cure Zika have already warned that a vaccine could take ten years until it is fully developed. Thus, most treatment with regards to Zika involves prevention, specifically for the pregnant women, babies, and infants for whom the effects of the virus can be significant. Those living in areas where Zika is prevalent are advised to try and avoid mosquito bites as much as possible, going out only at certain times of the day, avoiding certain areas, and using insect repellant, as this is the only way to prevent both catching the disease and spreading it to uninfected mosquitos. Those who have developed Zika fever should drink fluids and rest and can take acetaminophen painkillers, but must not take aspirins, ibuprofen, or other non-steroidal anti-inflammatory medications. This is because Zika fever is similar to its much deadlier cousins, such as dengue fever, and the symptoms of those diseases will only worsen with such medication. Thus such drugs are advised against until it can be determined with certainty that one is infected with Zika and not another member of the Flaviviridae family.


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