Togavirus: RubellaLongster Kemngang

http://www.sciencepicture.co/images/3643/Rubella-Virus.html

A 25-year-old man presents with a 3-day history of low-grade fever, malaise, headache, and aching knees. That morning he developed a rash on his face, which has now spread to his chest and arms. image His physical exam is notable for mild conjunctival injection, mild bilateral posterior auricular

lymphadenopathy, and a discrete erythematous papular rash on his face, trunk, and upper arms. The patient is from Mexico, has lived in the US for 6 months, and is unaware of his immunization status. He

reports that a coworker with whom he had close contact had a similar rash last week.

A 2820-gram (6lbs 2 oz) female infant is born to a 22-year old primigravidas mother at approximately 38 weeks' gestation following an uncomplicated pregnancy. The baby has mild hepatosplenomegaly, numerous purplish firm nonblanching skin nodules, scattered petechiae, and a grade 3 continuous

murmur audible at the left infraclavicular area. The baby's mother immigrated from Liberia during the sixth month of her pregnancy; she cannot recall having been immunized in childhood.

https://online.epocrates.com, 12 March 2015

Clinical Vignettes

RubellaTogaviridae : Rubivirus : Rubella/German Measles

DISEASE: GERMAN MEASLES (“3 DAY MEASLES”)

Enveloped Icosahedral Capsid Positive Single Stranded RNA

Rubivirus

Virus Replication Cycle

•Host : Humans

• Virus enters body via respiratory routea) replicates asymptomatically in URT in the nasopharyngeal mucosab) gains access to lymphatic system and subsequently enters bloodstream

•2 week incubation period (12-18 days)

Acquired Rubella

Medscape, 2015

•Rubella production in the pharynx precedes the appearance of symptoms and continues through the course of the disease.

•Fever and rash occur later. Patients are infectious for 7 days before and after rash appears.

•The onset of lymphadenopathy coincides with viremia

•The person is infectious as long the virus is produced in the pharynx.

Clinical Presentation

70% of Adults:Lymphoadenopathy (retroauricular and suboccipital), arthritis and arthralgias (adults)

Rash extends from face to the trunk and limbRash: maculopapular, non-confluent

Mild Disease Signs/Symptoms:* Fever* Postauricular adenopathy* Lymphadenopathy* Arthralgias* Fine truncal rash that starts at the head and moves down

Signs and Symptoms

Rubella Disease Timeline

Toxoplasma gondiiOther (varicella-zoster, parvovirus B19)RubellaCMVHIVHerpes simplex virus-2Syphilis

Congenital TORCHESMost common congenital manifestations

Congenital Rubella

Crosses placenta when mother has acute infection. The earlier the fetus is infected -> more serious disease.

May result in serious congenital abnormalities

◦ Intrauterine growth retardation

◦ Hepatosplenomegaly

◦ Cataracts

◦ Mental retardation

◦ Sensorineural hearing loss

◦ Heart- Patent ductus arteriosis

◦ Pulmonary stenosis

◦ Thrombocytopenic purpura

Cataracts

PDABlueberry Muffin Rash

Classic triad: PDA Cataracts, and

deafness +/- “blueberry

muffin” rash

viral excretion (+)

Pattern of Viral Excretion and Infant’s Antibody Response in Congenital Rubella

Clinical Laboratory Findings/Diagnosis

• Isolation of rubella virus from clinical specimen (e.g., nasopharynx, urine)

• Positive serologic test for rubella IgM antibody

• Significant rise in rubella IgG by any standard serologic assay (e.g., enzyme immunoassay)

•Treatment: No treatment, just supportive care•Prevention: MMR vaccine (Measles/Mumps/Rubella)

Treatment, Prevention & Control

Rubella VaccineVaccine Trade Name LicensureHPV-77:DE5 Meruvax 1969HPV-77:DK12 Rubelogen 1969GMK-3:RK53 Cendevax 1969RA 27/3* Meruvax II 1979*Only vaccine currently licensed in U.S.

• MMR vaccine: live attenuated virus Measles/Mumps/Rubella• Dramatic decline in the incidence of the disease since introduction of

vaccine• Periodic epidemics affect unvaccinated populations. Pro — induces strong, often life-long immunityCon — may revert to virulent form• USA Vaccination schedule: at 12-15 months and at 4 to 6 years

• Immunize at 9 months in endemic areas• Administer 1 dose of MMR vaccine to infants aged 6 through 11 months

before departure from the United States for international travel

• Efficiency: 95% lifelong immunization with a single dose

CDC, 2015

Differential DxRubella: Enveloped Icosahedral Capsid Positive Single Stranded RNA Measles: Paramyxoviruses Enveloped negative linear non segmented helical Single Stranded RNA

Rash: maculopapular, non-confluent (different from Measles: Rash presents last and spreads from head to toe. Koplik spots—not present in Rubella).

Extend from face to the trunk and limb (different from Exanthem roseola: surprise “almond-shaped” macule rash post fever on the trunk and neck)

Rubella has NO desquamation (different from Measles)

Crucial Symptom: Lymphoadenopathy (retroauricular and suboccipital), arthritis and arthralgias — 70% of Adults

Congenital:

Rubella and CMV are the only TORCH

viruses that have been documented by

skin biopsies to cause dermal

erythropoiesis

Viral exanthems : Varicella (VZV) , Rubella, Measles

Parvo B19 (Slap cheek) no vaccine;

EASY to mistake for rubella

Look for Anemia and NO Teratogenic

properties if congenital in Parvo B19

A 25-year-old man presents with a 3-day history of low-grade fever, malaise, headache, and aching knees. That morning he developed a rash on his face, which has now spread to his chest and arms. image His physical exam is notable for mild conjunctival injection, mild bilateral posterior auricular

lymphadenopathy, and a discrete erythematous papular rash on his face, trunk, and upper arms. The patient is from Mexico, has lived in the US for 6 months, and is unaware of his immunization status. He

reports that a coworker with whom he had close contact had a similar rash last week.

A 2820-gram (6lbs 2 oz) female infant is born to a 22-year old primigravidas mother at approximately 38 weeks' gestation following an uncomplicated pregnancy. The baby has mild hepatosplenomegaly,

numerous purplish firm nonblanching skin nodules, scattered petechiae, and a grade 3 continuous murmur audible at the left infraclavicular area. The baby's mother immigrated from Liberia during the

sixth month of her pregnancy; she cannot recall having been immunized in childhood.

Clinical Vignettes

https://online.epocrates.com, 12 March 2015

References

http://www.cdc.gov/rubella/index.html

Chantler, J., Wolinsky, J. S., & Tingle, A. (2001). Rubella Virus. In D. M.Knipe, & P. M. Howley (Eds.), Fields Virology (4th ed., pp. 963-990).

Philidelphia: Lippincott Williams & Wilkins.

Edlich, R. F., Winters, K. L., Long, W. B.,3rd, & Gubler, K. D. (2005). Rubella and congenital rubella (German measles). Journal of Long-Term

Effects of Medical Implants, 15 (3), 319-328.

De Santis, M., Cavaliere, A. F., Straface, G., & Caruso, A. (2006). Rubella infection in pregnancy. Reproductive Toxicology (Elmsford, N.Y.), 21 (4), 390-

398. doi:10.1016/j.reprotox.2005.01.014

Murray, Patrick R. PhD , Ken S. Rosenthal PhD. Medical Microbiology: with Student consult Online Access, 7e Paperback – November 28, 2012