Dengue Virus

Dengue is a mosquito-borne viral disease that has rapidly spread in tropical and subtropical regions of the world in recent years. 

Dengue is a mosquito-borne virus spread in several regions of the world 

Dengue has become a global problem since the Second World War and is common in more than 110 countries. The incidence of dengue has grown dramatically around the world in recent decades. The actual numbers of dengue cases are underreported and many cases are misclassified. One recent estimate indicates 390 million dengue infections per year, of which 96 million manifest clinically (with any severity of the disease). 

The dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and zika. Dengue is widespread throughout the tropics, depending on rainfall, temperature and unplanned rapid urbanization. There are four known serotypes of the dengue virus. Recovery from infection by one provides lifelong immunity against that particular serotype. However, cross-immunity to the other serotypes after recovery is only partial and temporary. Subsequent infections by other serotypes increase the risk of developing severe dengue.

Dengue fever virus (DENV) is an RNA virus of the family Flaviviridae; genus Flavivirus. Other members of the same genus include zika virus, yellow fever virus, West Nile virus, and Japanese encephalitis virus.

Zika Virus

Zika is transmitted primarily by Aedes mosquitoes. Microcephaly and Guillain-Barré syndrome are possibly caused by Zika infections.

Zika virus is a mosquito-borne flavivirus similar to dengue

The zika virus (ZIKV) is a member of the virus family Flaviviridae. It is spread by daytime-active Aedes mosquitoes, such as A. aegypti and A. albopictus. Its name comes from the Zika forest of Uganda, where the virus was first isolated in 1947. The zika virus is related to the dengue, yellow fever, Japanese encephalitis, and West Nile viruses. 

Since the 1950s, it has been known to occur within a narrow equatorial belt from Africa to Asia. The first large outbreak of zika infections was reported from the Island of Yap (Federated States of Micronesia) in 2007. Previously outbreaks of zika were recorded in Africa, the Americas, Asia and the Pacific. From 2007 to 2016, the virus spread eastward, across the Pacific Ocean to the Americas.

Probably the biggest zika outbreak in the history was recorded at the beginning of 2016. It has created a global concern about zika and its complications for pregnant women given the (now confirmed) correlation between zika infections and the increased number of the birth defects, such as microcephaly. Zika infections in adults may result rarely in Guillain–Barré syndrome. 

Zika can be also transmitted from men and women to their sexual partners. As of April 2016, sexual transmission of Zika has been documented in six countries – Argentina, Chile, France, Italy, New Zealand and the United States – during the 2016 outbreak.

Transmission of zika virus:

	Through mosquito bites Mosquitos become infected when they bite a person already infected with the virus. Infected mosquitos can then very efficiently spread the virus to other people.
	From mother to child A pregnant woman can pass the zika virus to her fetus during pregnancy.
	Through sex Zika virus can be passed through sex from a person who has zika to his or her sex partners.
	Through blood transfusion There is a strong possibility that zika virus can be spread through blood transfusions.