Saturday, January 30, 2016

What you should know about( Zika Virus) Cause by Aedes Mosquitoes

According to this write up on Wikipedia, Zika virus(ZIKV) is a member of the Flaviviridae virus family and the Flavivirus genus, transmitted by daytime-active Aedes mosquitoes, such as A. aegypti.

In humans, the virus causes a mild illness known as Zika fever, Zika, or Zika disease, which since the 1950s has been known to occur within a narrow equatorial belt from Africa to Asia. In 2014, the virus spread eastward across the Pacific Ocean to French Polynesia, then to Easter Islandand in 2015 to Mexico, Central America, the Caribbean, and South America, where the Zika outbreak has reached pandemic levels.

Zika virus is related to dengue, yellow fever, Japanese encephalitis, and West Nileviruses.

The illness it causes is similar to a mild form of dengue fever, is treated by rest, and cannot yet be prevented by drugs or vaccines.

There is a possible link between Zika fever and microcephalyin newborn babies by mother-to-child transmission, as well as a stronger one with neurologic conditions in infected adults, including cases of the Guillain–Barré syndrome.

In January 2016, the U.S. Centers for Disease Control and Prevention(CDC) issued travel guidance on affected countries, including the use of enhanced precautions, and guidelines for pregnant women including considering postponing travel.

Other governments or health agencies soon issued similar travel warnings, while Colombia, the Dominican Republic, Ecuador, El Salvador, and Jamaica advised women to postpone getting pregnant until more is known about the risks.

Along with other viruses in this family, Zika virus is enveloped
and icosahedraland has a nonsegmented, single-stranded, positive-sense RNAgenome. It is most closely related to the Spondweni virusand is one of the two viruses in the Spondweni virus clade.

The virus was first isolated in April 1947 from a rhesus macaquemonkey that had been placed in a cage in the Zika Forest of Uganda, near Lake Victoria, by the scientists of the Yellow Fever Research Institute. A second isolation from the mosquito A. africanus followed at the same site in January 1948.

When the monkey developed a fever, researchers isolated from its serum a transmissible agent that was first described as Zika virus in 1952. In 1968, it was isolated for the first time from humans in Nigeria.

From 1951 through 1981, evidence of human infection was reported from other African countries such as the Central African Republic, Egypt, Gabon, Sierra Leone, Tanzania, and Uganda, as well as in parts of Asia including India, Indonesia, Malaysia, the Philippines, Thailand, and Vietnam.

There are two lineages of Zika virus, the African lineage and the Asian lineage.

Phylogenetic studies indicate that the virus spreading in the Americas is most closely related to French Polynesian strains.

Complete genome sequences of Zika viruses have been published.

Recent preliminary findings from sequences in the public domain uncovered a possible change in nonstructural protein 1codon usage that may increase the viral replication rate in humans.


Aedes aegypti—a mosquito vector of Zika virus

Zika virus is transmitted by daytime-active mosquitoes and has been isolated from a number of species in the genus Aedes, such as A. aegypti, and arborealmosquitoes such as A. africanus, A. apicoargenteus, A. furcifer, A. hensilli, A. luteocephalus, and A. vitattus.

Studies show that the extrinsic incubation periodin mosquitoes is about 10 days.

Zika virus can migrate between humans through sexual contact and it can also cross the placenta, affecting an unborn fetus. A mother already infected with Zika virus near the time of delivery can pass on the virus to her newborn around the time of birth, but this is rare.

The vertebrate hosts of the virus are primarily monkeysand humans. Before the current pandemic, which began in 2007, Zika virus "rarely caused recognized 'spillover' infections in humans, even in highly enzooticareas".


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