Dark green denotes countries with current or previous local transmission of<unk> V, per CDC as of Sept 17, 2019. A. albopictus distribution as of December 2007 Dark blue: Native rangeTeal: introduced Historically,<unk>  has been present mostly in the developing world. The disease causes an estimated 3 million infections each year. Epidemics in the Indian Ocean, Pacific Islands, and in the Americas, continue to change the distribution of the disease. In Africa,<unk>  is spread by a sylvatic cycle in which the virus largely cycles between other non-human primates, small mammals, and mosquitos between human outbreaks. During outbreaks, due to the high concentration of virus in the blood of those in the acute phase of infection, the virus can circulate from humans to mosquitoes and back to humans. The transmission of the pathogen between humans and mosquitoes that exist in urban environments was established on multiple occasions from strains occurring on the eastern half of Africa in non-human primate hosts. This emergence and spread beyond Africa may have started as early as the 18th century. Currently, available data does not indicate whether the introduction of<unk>  into Asia occurred in the 19th century or more recently, but this epidemic Asian strain causes outbreaks in India and continues to circulate in Southeast Asia. In Africa, outbreaks were typically tied to heavy rainfall causing increased mosquito population. In recent outbreaks in urban centers, the virus has spread by circulating between humans and mosquitoes. Global rates of<unk>  infection are variable, depending on outbreaks. When<unk>  was first identified in 1952, it had a low-level circulation in West Africa, with infection rates linked to rainfall. Beginning in the 1960s, periodic outbreaks were documented in Asia and Africa. However, since 2005, following several decades of relative inactivity,<unk>  has re-emerged and caused large outbreaks in Africa, Asia, and the Americas. In India, for instance,<unk>  re-appeared following 32 years of absence of viral activity. Outbreaks have occurred in Europe, the Caribbean, and South America, areas in which<unk>  was not previously transmitted. Local transmission has also occurred in the United States and Australia, countries in which the virus was previously unknown. In 2005, an outbreak on the island of Réunion was the largest then documented, with an estimated 266,000 cases on an island with a population of approximately 770,000. In a 2006 outbreak, India reported 1.25 million suspected cases.<unk>  was recently introduced to the Americas, and from 2013 to 2014 in the Americas, 1,118,763 suspected cases and 24,682 confirmed cases were reported by the PAHO. An analysis of the genetic code of<unk>  virus suggests that the increased severity of the 2005–present outbreak may be due to a change in the genetic sequence which altered the E1 segment of the virus' viral coat protein, a variant called E1-A226V. This mutation potentially allows the virus to multiply more easily in mosquito cells. The change allows the virus to use the Asian tiger mosquito (an invasive species) as a vector in addition to the more strictly tropical main vector, Aedes aegypti. Enhanced transmission of<unk>  virus by A. albopictus could mean an increased risk for outbreaks in other areas where the Asian tiger mosquito is present. A albopictus is an invasive species which has spread through Europe, the Americas, the Caribbean, Africa and the Middle East. After the detection of zika virus in Brazil in April 2015, the first ever in the Western Hemisphere, it is now thought some<unk>  and dengue cases could in fact be zika virus cases or coinfections.
Chikungunya
Zika fever
Yellow fever
Dengue fever
Trench fever
Rocky Mountain spotted fever
Cuban fever
Blackwater fever