Most of the flavivirus species have tissue tropism to neural tissue. This explains their most debilitating effects on humans, such as encephalitis. There are over 50 various flavivirus species, but not all of them are known to cause human disease 1. Some key species that do cause human disease will be the focus of this blog, and they include:
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The incubation period for JEV is about 5-15 days; and like other flaviviruses, this virus commonly causes subclinical infections, with no apparent signs and symptoms. However, in about 1/250 infections, acute encephalitis can occur and may ultimately lead to seizures, paralysis, come and death.
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At least 27 alphaviruses and 68 flaviviruses have been recognized, approximately one-third of which are medically important human pathogens. They vary widely in their basic ecology; each virus occupies a distinct ecologic niche, often with restricted geographic and biologic distribution.
https://www.ncbi.nlm.nih.gov/books/NBK7633/
The flavivirus genus comes from the Flaviviridea family of viruses, which are classified as arthropod-borne viruses. Flavivirus species can be transmitted to humans via either a mosquito or tick vector. The flavivirus genera are of importance to the medical community because they have been found to be the causative agent of many endemic and epidemic illnesses across the world.
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As shown in Tables 54-1 and 54-2, alphaviruses and flaviviruses can cause various syndromes, ranging from benign febrile illnesses to severe systemic diseases with hemorrhagic manifestations or major organ involvement. The neurotropic alphaviruses and flaviviruses can produce severe destructive central nervous system disease with serious sequelae. Several alphaviruses (chikungunya, Mayaro, and Ross River) cause painful arthritis that persists for weeks or months after the initial febrile illness.
https://www.ncbi.nlm.nih.gov/books/NBK7633/
Flavivirus virions are spherical, ca. 50 nm in diameter, and consist of a nucleoprotein capsid enclosed in a lipid envelope. The RNA is a single 40S (ca. 10.9 kilobases) positive-sense strand and is capped at the 5′ end, but, unlike alphaviruses, has no poly A segment at the 3′ end.
https://www.ncbi.nlm.nih.gov/books/NBK7633/
Many time, an individual may be infected with one of these flavivirus species and not ever be aware, as asymptomatic infections are common in regard to flavivirus infections. However, severe infection of certain flaviviruses can lead to serious complications, such as inflammation of the brain, hemorrhage, and death. Below are the signs, symptoms, and clinical information regarding the 5 flaviviruses listed above. Yellow Fever
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The incubation period for yellow fever is about 3-6 days, followed by 3 stages of infection, detailed below3: 1  Early Stage: The first symptoms that may appear after being infected with this flavivirus include fever, headache, muscle aches, vomiting, loss of appetite, and jaundice.
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Alphavirus is one of the two genera in the family Togaviridae; the other genus (Rubivirus) has rubella virus (Chapter 55) as its only member. Flavivirus, once classified in the Togaviridae, now constitutes one of three genera in the family Flaviviridae; the other two genera are Pestivirus and “Hepatitis C-like viruses”.
https://www.ncbi.nlm.nih.gov/books/NBK7633/
Most of the flavivirus species have tissue tropism to neural tissue. This explains their most debilitating effects on humans, such as encephalitis. There are over 50 various flavivirus species, but not all of them are known to cause human disease1.
https://flavivirus.wordpress.com/medical-relevance/
flavivirus causes
Flaviviruses can cause various syndromes, ranging from benign febrile illnesses to severe systemic diseases with hemorrhagic manifestations or major organ involvement.