Microbiology
Summary
The Flaviviridae family consists of enveloped viruses with non-segmented positive-sense RNA. Many flaviviruses are arboviruses, transmitted by insects like ticks and mosquitoes during blood meals.
One prominent member of Flaviviridae is the hepatitis C virus, which belongs to the Hepacivirus genus. Dengue virus, transmitted by the Aedes aegypti mosquito, is the cause of dengue fever, which is characterized by bone marrow suppression, thrombocytopenia, hemorrhage, and can progress to hemorrhagic fever, renal failure, and septic shock in severe cases. Preventive measures include vector control and a tetravalent live attenuated vaccine for those with a history of dengue virus fever. Yellow fever virus, another flavivirus transmitted by the Aedes aegypti mosquito, is endemic to countries in Africa and Southern/Central America. Yellow fever leads to jaundice, lumbosacral muscle pain, and hemorrhagic symptoms. A live attenuated vaccine helps prevent yellow fever, recommended for travelers to Africa and South America. West Nile virus, transmitted by Culex spp. mosquitoes, is maintained in nature through a cycle involving birds as reservoir hosts. It causes neuroinvasive disease such as encephalitis, meningitis, and neurological dysfunction. Zika virus, another virus transmitted by the Aedes aegypti mosquito, is associated with congenital Zika syndrome, Guillain-Barr≈Ω syndrome, and vertical/sexual transmission. The Flaviviridae family also includes tick-borne hemorrhagic fever viruses causing hemorrhage and encephalitis.
Lesson Outline
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FAQs
The Flaviviridae is a family of viruses that has more than 70 members and is split into four genera: Flavivirus, Hepacivirus, Pestivirus, and Pegivirus. Flaviviruses include the hepatitis C virus, which belongs to the Hepacivirus genus, and the West Nile virus, yellow fever virus, dengue fever virus, and Zika virus, which all belong to the Flavivirus genus.
Many viruses in the Flaviviridae family, such as the yellow fever virus, dengue virus, West Nile virus, and Zika virus are arboviruses, meaning they are transmitted by arthropod vectors. Aedes aegypti, a species of mosquito, is a primary vector for these viruses other than the West Nile virus, which is transmitted by Culex spp. mosquitoes.
The West Nile virus is the most prevalent vector-borne virus in the US. It is transmitted to humans through the bites of infected mosquitoes, primarily those of the Culex species. While most individuals infected with West Nile virus do not experience symptoms, some may develop mild flu-like symptoms. In more severe cases, the infection can lead to neuroinvasive diseases such as encephalitis, meningitis, and other neurological complications.
Dengue fever is marked by symptoms such as high fever, severe headache, joint and muscle pain, and a rash that typically spreads from the torso to the limbs. Patients may experience pain behind the eyes and have a decreased platelet count, leading to a tendency for bleeding. In severe cases, dengue fever can progress to dengue hemorrhagic fever or dengue shock syndrome, which involve more severe bleeding, organ failure, and shock.
Zika virus infection during pregnancy can lead to a range of complications in newborns, collectively known as congenital Zika syndrome. These complications can include microcephaly, where babies are born with abnormally small heads and underdeveloped brains, leading to developmental delays and intellectual disabilities. Other potential outcomes include eye abnormalities, hearing loss, impaired growth, and joint problems. The virus can also result in stillbirth or miscarriage in some cases.
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