Measles is an infectious disease caused by a virus of the genus morbillivirus belonging to the Paramixoviridae family.
The measles virus is highly contagious and is transmitted via air through secretions from the nose, mouth and throat. Indirect infection is very rare. Infectiousness begins 2-3 days before the rash appears and lasts for about 5 days after its onset.
Symptoms and complications
The incubation period lasts from 8 to 14 days. The clinical symptomatology during the invasion period is characterised by high fever, rhinitis, pharyngitis and conjunctivitis. Before the onset of the rash, white specks may appear inside the cheeks (Koplik spots). The rash begins in the retro auricular regions and within 2-3 days spreads to the face, neck, trunk and limbs. In uncomplicated cases, around four days after its onset, the rash begins to pale following the order in which it appeared. When the rash disappears, desquamation (peeling skin) remains, but does not usually affect the palms of the hands and the soles of the feet.
There is no specific treatment for measles, thus it only deals with the symptoms. Paracetamol is used to reduce fever, syrups to alleviate cough and eye drops to reduce eye discomfort. Antibiotics are used only if complications arise. Diarrhoea can occur, which is why it is important for the patient to remain hydrated.
About 30% of measles cases can develop one or more complications, with a higher frequency in children under 5 or in adults over 20. The most frequent complications of measles are: diarrhoea (8%), otitis media (7%) and pneumonia (6%). Acute encephalitis can occur in 0.1% of cases, usually from 2 days to 3 weeks after the onset of the rash, often with high fever, headache, vomiting, neck stiffness, convulsions and coma. In a quarter of the cases of acute encephalitis, some form of neurological damage remains. Measles is rarely fatal in developed countries, but mortality can be higher in the first years of life and the most frequent causes of death are respiratory complications and encephalitis.
A very rare complication called Subacute Sclerosing Panencephalitis (PESS) exists; it is a degenerative disease of the CNS probably due to the persistence of the measles virus in the central nervous system. It can also appear several years after infection in about 5-10 cases per 1,000,000 measles cases. PESS causes intellectual deterioration, convulsions and motor abnormalities, leading to death, within a timeframe of 1-3 years.
Impact on the population
Before mass vaccination, measles outbreaks occurred every 2-3 years, with small localised outbreaks during inter-pandemic years. The infant whose mother has already had measles receives a passive trans-placental immunity that lasts for most of the first year of life; subsequently the susceptibility to measles is high.
A single episode of measles confers lifelong immunity.
In 2002, a vast measles epidemic occurred in Italy, with an estimate of over 40,000 sick children, more than 600 hospitalisations, 15 cases of encephalitis and 6 deaths. Subsequently, in 2003, the actions of the first "Measles Elimination Plan" allowed for the lowest incidence of measles ever recorded, in 2005. Despite this, however, there is still a large number of individuals susceptible to infections due to the failure of vaccination coverage to exceed 95% for some age groups.
It is important to note that 88% of the measles cases recorded in Italy concerned people who had never been vaccinated.
For this reason, a new "National Plan for the Elimination of Measles and Congenital Rubella (PNEMoRC) 2010-2015" was recently approved at the State-Regions Conference.
Sources / Bibliography
- Piano Nazionale di eliminazione del morbillo e della rosolia congenita (PNEMoRC) 2010-2015
- Epidemiology and Prevention of Vaccine-Preventable Diseases, The Pink Book: Course Textbook, 12th Edition Second Printing (May 2012)