Measles virus is an enveloped virus that causes the highly contagious disease measles. It enters the body through respiratory secretions and multiplies locally before spreading systemically. This causes a characteristic rash and other symptoms. Laboratory diagnosis involves detecting viral antigens, isolating the virus, or detecting antibodies. Vaccination with live attenuated vaccines provides effective long-term protection against measles.

1. GENUS MORBILLIVIRUS
MEASLES (Rubeola)

2. MEASLES (RUBEOLA)
• Ancient disease, no clear extinction was made between measles or other
exanthematous diseases including smallpox.
• Thomas Syndenham (1960) accurately described measles.
• Viral origin was established by Goldberger and Anderson in 1911 through inoculation of
blood filtrates and nasopharyngeal secretions from Patients.
• Virus was isolated in monkey and human kidney cells by Enders and Peebles in 1954.

3. MEASLES VIRUS
• Roughly spherical, often pleomorphic particle, 120 to 250nm in diameter, tightly coiled helical
nucleocapsid surrounded by lipoprotein envelope on its surface hemagglutinin (H) spikes.
• Envelope has F protein which mediates cell fusion and haemolytic activities.
• Agglutinates monkey erythrocytes but there’s no elution as the virus doesn't posses
neuraminidase activity.
• Grows well on human or monkey kidney and human amnion cultures for primary isolation.
• Isolates can be adapted for growth on continuous cell lines (HeLa, Vero) and in amniotic sac of
hen’s eggs.
• Cytopathic effects consists of multinucleate syncytium formation, with numerous acidophilic
nuclear and cytoplasmic inclusions.
• Multinucleate giant cells (Warthin- Finkeldey cells) are seen in lymphoid tissues of patients.

4. • Labile, readily heat inactivated, ultraviolet light, ether and formaldehyde.
• Can get stabilised by molar magnesium sulphate, so that it resists heating
at 50֯C for 1hour.
• Measles virus is antigenically uniform.
• Shares antigen with viruses of canine distemper and bovine rinderpest.

5. CLINICAL FEATURES
• Takes 9 to 11 days from exposure time to infection for first signs of clinical disease to
appear.
• Consist of prodromal malaise, fever, conjunctival injection, cough and nasal discharge.
• Rashes appears after 3-4 days of prodromal illness.
• Before a day or two the rash begins, Koplik’s spots develop on the buccal mucosa,
occasionally on conjunctiva and intestinal mucosa.
• Illness subsides within a day or two of rash’s appearance.
• Red maculopapular rash of measles appears on forehead first, spreads downwards, to
disappear in the same sequence 3-6 days later, leaving behind a brownish
discolouration and finely granular desquamation.
• Patients recover uneventfully, but few develop complications due to virus (croup,
bronchitis) or to secondary bacterial infection (pneumonia, otitis media).

6. • Rarely, virus may cause fatal giant cell pneumonia, particularly in children with
immunodeficiencies or severe malnutrition.
• Complications are common and serious in developing countries.
• Most serious complication is meningoencephalitis.
• Survivors have neurological sequelae.
• A rare late complication is subacute sclerosing panencephalitis (SSPE).
• Protracted diarrhea is often seen as a complication in children in poor nations.
• Virus may be recovered from stools of patients with measles enteritis.
• Occurs as a suppression of delayed hypersensitivity after measles infection, which may
last for weeks or few months.
• Mantoux and other skin tests may be negative during this period.

7. • Underlying tuberculosis may become worse.
• Recovery of measles is associated with the improvement of allergic eczema or asthma,
Hodgkin’s disease or lipoid nephrosis
• Measles induces labour in pregnant women.
• Results in spontaneous abortion or premature delivery.
• Virus may cross the placenta and infect the fetus during maternal measles but there’s no
evidence of teratogeny.
• Thrombocytopenia may develop, leading to purpura and bleeding from mouth, intestines
and genitourinary tract.

8. PATHOGENESIS
• virus enters body through respiratory tract or conjunctiva and multiplies locally and in the
adjoining lymph nodes.
• Spreads to reticuloendothelial system through blood.
• After multiplication, a secondary viremia transports virus to epithelial surfaces including the skin,
mouth, respiratory tract and conjunctiva.
• Pathogonomic Koplik’s spots (small bluish white ulcerations) on buccal mucosa opposite to lower
molars contain giant cells, cytoplasmic and intranuclear inclusions and virion components,
indicating local viral replication.

9. • Viral replication evidence can be seen in vascular endothelial cells at the sites of the
skin rash.
• Rash is an immune reaction between T-lymphocytes and cells in which viral replication
takes place.
• Virus can be isolated from blood, washed leucocytes, tears and respiratory secretions
during the 2-4 days of prodromal period.
• Can be recovered from urine upto 4 days after the appearance of skin rash.

10. LABORATORY DIAGNOSIS
• Diagnosis is self-evident in case of typical case of measles.
• In atypical cases and differentiation from rubella, laboratory tests are useful.
• Measles virus antigen can be defected in these cells by immunofluorescence.
• Multinucleated giant cells can be diagnosed in Giemsa – stained smears of nasal secretions.
• Virus can be isolated from nose, throat, conjunctiva and blood during prodromal phase and upto
2 days after rash appearance.
• Virus can be obtained from urine.
• Primary human or monkey kidney and amnion cells are most useful.
• Cytopathic changes may take upto a week to develop.
• Earlier diagnosis of viral growth is possible by immunofluorescence.

11. SEROLOGICAL DIAGNOSIS
• Specific neutralisation, hemagglutination inhibition and complement fixing antibodies develop
early.
• A 4 fold rise in titre is looked for using sera collected during the acute phase and 10-21 days
later.
• Demonstration of measles-specific IgM in a single specimen of serum drawn between 1 and 2
weeks after the onset of the rash is confirmatory.
• False negatives may occur if the serum is taken earlier than 1 week before or later than the 2
weeks after the onset of the rash.
• Demonstration of high titre measles antibody in the CSF is diagnostic of SSPE.

12. EPIDEMIOLOGY
• Endemic and produces epidemics (seen in late winter or early winter) every 2-3 years.
• Disease has maximum incidence in children of 1-5 years.
• Uncommon in first 6 months of life due to the presence of maternal antibody.
• One attack confers solid immunity.
• People are natural hosts of measles.
• Monkeys are often infected but they seem to acquire the infection from humans.
• Patients are infectious from 3 days before to the onset of symptoms until the rash desquamates.
• Infectivity is maximum at the prodrome and diminishes rapidly on the onset of rash.
• Spread by direct contact with respiratory secretions and aerosols by coughing and sneezing.
• Virus enters through respiratory tract and conjunctiva.
• In nonimmune, infection results in clinical disease.

13. PROPHYLAXIS
• Normal human gammaglobulin given within 6 days of exposure can prevent or modify the
disease, depending on the dose.
• Valuable in children with immunodeficiency, pregnant women and others at special risk.
• Safe and effective live attenuated measles vaccine is available.
• Original live vaccines used the Edmonston strain developed by multiple passage through human
kidney, amnion and chick embryo cultures.
• Have high risk of febrile rash (vaccination measles), further attenuation became necessary.
• Schwartz and Moraten strains so developed were safe but effective only in children older then 15
months.
• Edmonston- Zagreb strain, attenuated by passage in human diploid cells, is preferred as vaccine
strain because it is able to produce seroconversion even in infants 4-6 months old.

14. • Recommended age for measles vaccination in developing countries is 9 months while
in advanced nations is 15 months.
• Vaccine is either given by itself, or in combination, as the MMR vaccine.
• A single subcutaneous injection provides protection beginning in about 12 days and
lasting for over 20 years.
• Contraindications are immunodeficiency, untreated tuberculosis and pregnancy.
• Live attenuated vaccine is developed which can e given intranasal aerosol in young
babies and gives good protection irrespective of the presence of maternal antibodies.