Measles Virus

Question 1

Classification

Answer 1

Family: Paramyxoviridae

Genus: Morbillivirus

Species: Measles virus

(Hint: occurs in the night time, with clothes on)

Question 2

Characteristics

Answer 2

• enveloped virus
• helical nucleocapsid
• -ssRNA
• virion RNA polymerase
• one serotype
• cytoplasmic/ nuclear replication —> intranuclear and intracytoplasmic inclusions

Question 3

Transmission

Answer 3

Respiratory droplets

Question 4

Pathogenesis

Answer 4

• Initial site of infection&raquo_space;>_ upper respiratory tract&raquo_space;> replicates

- Virus spreads to local lymph nodes and then via the blood to other organs:
Skin
Lungs
Conjunctiva
CNS

S C C L

Question 5

Disease

Answer 5

Measles

1) Prodrome phase/ catarrhal phase

• upper respiratory tract infection: sneezing, coughing, running nose
• conjunctivitis
• Koplik’s spots = red macular ulcers with a bluish-white centre —> in mucous membranes of the inside of the cheeks

2) Eruptive phase
- Maculopapular rash (due to cell-mediated immune attack by cytotoxic T cells) —> downwards direction (head —> chest/trunk —> limbs)
- fever

3) Postmeasles/ pigmentation phase
- Rash becomes brownish —> fades by desquamation —> recovery

Question 6

Microbiological diagnosis

Answer 6

• the virus is rarely isolated —> grows very slowly —> multinucleate giant cells after 7 - 10 days

> confirmation —> immunofluorescence staining

• serologic tests are used if necessary —> neutralization, ELISA
• PCR is available

Question 7

Treatment and prevention

Answer 7

Treatment:

• No antiviral drug
• Vitamin A supplements are given —> reserves fall rapidly during measles

Prevention:

• Live-attenuated vaccine in 2 forms:
  MMR —> live attenuated measles, mumps and rubella vaccines
  MMRV—> live attenuated measles, mumps, rubella and varicella vaccines

Usually MMR vaccine is given = (trimovax)

Children with measles must be kept out of school for 4 days after appearance of rash