Microbiology
Summary
The Paramyxoviridae family, which includes the measles virus, mumps virus, and parainfluenza virus, are enveloped viruses with single-stranded, negative-sense RNA genomes and helical nucleocapsids primarily spread through respiratory droplets.
Measles (also known as rubeola) often presents with high fever, a confluent maculopapular rash, cough, coryza, conjunctivitis, and Koplik spots, small white or bluish-gray spots with red borders that appear inside the mouth. Potential complications of measles include pneumonia and subacute sclerosing panencephalitis (SSPE), a rare, progressive neurological disorder. Vitamin A reduces the risk of complications of the measles, including death. The measles virus expresses the hemagglutinin (HA) and fusion protein. The mumps virus replicates in the parotid glands and can cause orchitis and meningitis. This virus expresses HA, NA, and the fusion protein. The parainfluenza virus causes croup, which is characterized by inspiratory stridor and the steeple sign on X-ray. Just like mumps, it also expresses all three HA, NA, and the fusion protein virulence factors. The measles, mumps, and rubella (MMR) vaccine is a live vaccine used for prevention, but is not suitable for pregnant individuals or those with immunocompromising conditions.
Lesson Outline
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FAQs
Paramyxoviruses are a family of RNA viruses that include measles, mumps, and parainfluenza viruses. These viruses are unique because they are larger in size than most RNA viruses and exhibit a negative-sense single-stranded RNA genome. They have a lipid envelope with spike proteins that facilitate entry into host cells.
The MMR vaccine protects against measles, mumps, and rubella (German measles) Ð diseases caused by three different viruses. A dose of the MMR vaccine is roughly 93% effective in preventing measles, if exposed to the virus, and the second dose increases this to around 97%. It is about 78% effective in preventing mumps and 97% effective in preventing rubella.
Koplik spots are small white spots that appear inside the mouth, often on the inside of the cheeks, in the early stages of measles illness. They are considered a characteristic sign of measles (rubeola). Appearance of these spots generally precedes the measles rash by one to two days.
Subacute sclerosing panencephalitis (SSPE) is a rare progressive neurological disorder of children and young adults that affects the central nervous system (CNS). It is a late complication of measles virus infection and typically develops 7 to 10 years after the initial measles infection. SSPE is characterized by behavioral changes, cognitive decline and, eventually, severe motor dysfunction.
Orchitis is inflammation of one or both testes, usually caused by infection. Mumps is the most common infectious cause of orchitis in post-pubertal males. Typically, orchitis occurs about a week after the onset of mumps, causing pain, swelling and potentially decrease in testicular size and potential infertility.
