Rubella virus (German measles)

Microbiology

Seasonal, in spring, if no vaccine
Less contaggious than measles, spread by respiratory droplets
- Most contagious while the rash is erupting, but ranges from 10 days prior to 15 days after
- Infants with congenital rubella can shed it in body fluids for months
Epidemics happened every 6 to 9 years, with larger epidemics every 30 years
Worldwide, until it was eliminated in the Americas in 2009
- All cases are imported

Incubation period 18 days (range 12 to 23 days)
Benign after birth (postnatal rubella)
In adults, prodrome of fever, malaise, and anorexia, followed by the rash
Rash appears along with development of immunity
- Rash starts at the head and moves down
- Maculopapular
- May desquamate during healing
- May be absent
- Can have Forschheimer's spots (petechial lesions on the soft palate), but not pathognomonic
Adenopathy can last weeks, primarily posterior auricular, posterior cervical, and suboccipital
Can develop arthritis in a third, usually fingers, wrists, and knees
- Onset soon after the rash, can take up to a month to resolve
Hemorrhage from thrombocytopenia and vascular damage, more commonly in children
Encephalitis is rare

Deafness, cataracts, glaucoma, congenital heart disease, and mental retardation
Low birth weight, thrombocytopenic purpura, organomegaly, meningoencephalitis, retinopathy, PDA, PS, developmental disorders, cryptorchidism, inguinal hernia

First trimester infection is more likely to have congenital rubella, rare in third trimester
Confirm vaccination status of the exposed individual, in which case they will be very low risk