Infection spread through respiration:- MEASLES

Measles is an ancient disease, but for a long time no clear distinction was made from small pox. It was only in 1629 that measles came to be considered as a separate unit. The classical study of this epidemic by Peter Panum, a Danish medical student laid the scientific basis about measles.

The viral etiology of measles was established by Doldberger and Anderson in 1911. The virus was isolated from human kidney cells and in monkeys by Enders and Peebles in 1954.

The virus is roughly spherical in shape, but often pleomorphic. A tightly coiled helical capsid is surrounded by a lipoprotein envelope. It bears hemagglutinin (H) spikes on them.

The virus grows well on human kidney cells as well as in the amnion cultures. The amniotic sac of hen’s egg is also good growth mediators. Multinucleate giant cells (Warthin- Finfeldey cells) are also found in the lymphoid tissues of the patients.

The virus is labile, and easily inactivated by heat, ultraviolet light, ether and formaldehyde. It can resist heating at 50^oC for one hour.

It takes about 9- 11 days from the time of exposure to infection for the first signs of clinical disease to appear. This starts off with;

• General uneasiness
• Fever
• Conjunctival injection (redness of the eyes due to the dilation of blood vessels)
• Cough
• Nasal discharge

Rashes start to appear after 3- 4 days of initial illness. A day or before the rashes appear, characteristic spots called Koplik’s spots develops on the buccal mucosa and at times on the conjunctiva and intestinal mucosa.

The initial illness subsides within a day or two of the appearance of the rash. The red maculopapular rash (flat spot with confluent bumps) of measles develops at first on the forehead.

It slowly spreads downwards and disappears within 3- 6 days, leaving behind a brownish discoloration and finely granular peeling of the skin. Most patients recover uneventfully, but quite a few develop complications which may be due to the virus. There are chances for secondary infections by bacteria (pneumonia).

Prolonged diarrhea is often seen as a complication in children of poor countries. The virus may be recovered from the stool of patients with measles enteritis.

Delayed hypersensitivity is suppressed after measles infection for about a week or a few months. Underlying tuberculosis may become worse during this period. Recovery from measles may also be associated with an improvement of asthma.

Measles induce labor in some pregnant women, resulting in spontaneous abortion or premature delivery. Bleeding from the mouth, intestine and genitourinary tract also are complications.

The virus normally enters the body through eh conjunctiva or the respiratory tract. It multiplies locally and in the lymph nodes. After spreading to the reticuloendothelial system through the blood, a secondary viremia occurs. This transports the virus to the epithelial surfaces including the skin, mouth, respiratory tract and conjunctiva.

The early phases demonstrate the virus from blood, tears and respiratory secretions. It appears in the urine up to five days after the appearance of the skin rash.

Normal human gammaglobulin given within 6 days of exposure modifies the disease. The vaccine is given either by itself or in combination as the MMR vaccine.

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