Paramyxoviridae
Measles, sneezles, and things that go mumps in the night

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Julie Boiko, Class of 2010

Humans & Viruses II

Stanford University

General Information

Paramyxoviruses (Greek para: "by the side of," myxa: "mucus") are part of the mononegavirales order.  Paramyxoviridae contains many member species, though most of these viruses appear to have a narrow host range.  Genomes of this family contain single-stranded, negative sense RNA genomes.  Their nucleocapsids are enveloped helices. As shown on the right, the virion (150-350 nm) has a somewhat spherical, pleomorphic appearance.

There are six genera in the Paramyxoviridae family: Avula, Henipa, Metapneumo, Morbilli, Paramyxo, Pneumo, and Rubula.  Each genus contains 6-10 genes.  All genera except Avulaviruses infect humans.

 

Paramyxoviruses include a wide range of disease-causing viruses: measles, mumps, parainfluenza, and respiratory syncytial virus (RSV).  In recent years, the Menangle, Tioman, Hendra, and Nipah viruses have emerged.  Notable non-human paramyxoviruses include Sendai virus, Newcastles disease virus, and canine distemper virus.

 

Measles

Measles was first documented in the tenth century by Arabic physicians who thought that the disease was a mild form of smallpox.  It wasn't until the 1600s that Sydenham distinguished measles from the poxviruses.

 

Measles typically presents after 1 seven- to 18-day incubation period with a maculopapular rash which originates on the face and spreads to the rest of the body.  Several days before the full rash, small, irregular spots, termed Koplik's spots, appear inside the cheek.  The rash is frequently accompanied by respiratory symptoms - cough, coryza, and conjunctivitis.

 

Post-measles complications may include pneumonia, otitis media, and diarrhea.  More serious complications include post-infectious encephalitis and subacute sclerosing panencephalitis (SSPE).  Post-infectious encephalitis occurs in the recovery period of 0.1% of measles cases and results in nerve demyelination.  SSPE may arise anywhere from one to 10 years after original measles infection due to persistent viruses remaining in the body and replicating in the brain.  This manifests itself in one in a million measles cases and results in mental and motor deterioration.

 

Mumps 

Mumps was initially documented by Hippocrates 2,500 years ago when he described an epidemic of parotitis and orchitis.  The term "mumps" became common in the late 1500s.  Increasing awareness of the virus in the 20th century led to great strides in vaccine development and licensure of the MMR vaccine in preventing the disease, along with rubella and fellow paramyxovirus measles.

Though mumps infection in infants is rarely symptomatic, children and adults are commonly afflicted with parotitis.  Post-pubertal males may experience orchitis, inflammation of the testes, frequently resulting in sterility.  Serious mumps complications include meningitis and encephalitis (leading to unilateral hearing loss)