NAME: Measles virus
SYNONYM OR CROSS REFERENCE: MV, measles, morbilli, rubeola, pneumonia, measles inclusion body encephalitis, encephalomyelitis, atypical measles, subacute sclerosing panencephalitis, red measles, 5 or 10-day measles, hard measles Footnote 1.Footnote 3.
CHARACTERISTICS: Measles virus is a negative-sense, single stranded RNA virus, which belongs to morbillivirus genus in the Paramyxoviridae family Footnote 1. It cnsists of a helical nucleocapsid, 100-300 nm in diameter, surrounded by an envelope. The envelope is lined by matrix proteins and carries transmenbrane hemaglutinin and fusion glycoproteins which are the virulence factors.
PATHOGENICITY/TOXICITY: The Measles virus may cause measles, a systemic infection starting in the respiratory epithelium of the nasopharynx Footnote 3 Footnote 4. Measles may lead to severe complication and can cause death. After an incubation period of 8-12 days, fever (approximately 38.3°C) and malaise develop over 24 hours Footnote 3. These symptoms are followed by cough, coryza (inflammation of the nasal mucous membranes) and conjunctivis. After 2-3 days of cough, coryza and conjunctivitis, Koplik spots (white and granular lesions in the lateral buccal mucosa) appear. On the forth day, a macropapular rash appears on the head and neck, behind the ears. The rash then spreads to the rest of the body and persists for 3-5 days before fading Footnote 2. Other symptoms include anorexia and dyspnea Footnote 5. Subjective improvement can begin 2-4 days after the rash first appears Footnote 3. Infants, pregnant women, immunocompromised and malnourished patients are at a greater risk of developing complications, and experience more severe illness Footnote 3 Footnote 4. Historically, males have had a higher mortality rate than females, but this difference has tended to decrease with modernization of healthcare in western countries. Common complications include bacterial superinfection, which results in otitis media (middle ear infection), bronchitis, croup and pneumonia (3.5-50% cases), lymphadenopathy, diarrhea and encephalitis (1 in 1,000 cases) Footnote 3. Pneumonia is the main cause of mortality. Encephalitis may result in coma and brain damage (25%) or death (15%). Rarer complication includes thrombocytopenic purpura, myocarditis, subacute sclerosing panencephalitis, abdominal pain and acute appendicitis. During pregnancy, measles results in increased risk of spontaneous abortion and preterm birth. In industrialized countries, the fatality rate is 1-2 per 1,000 cases Footnote 4, while is it 15-25% in developing countries Footnote 2. People vaccinated with killed vaccine (used between 1963 and 1968 and abandoned because protection was too short) or who receive immunoglobulin as a prophylactic measure 6 days after infection may develop atypical measles Footnote 4 . They may experience higher fever, prominent rash (often with petechia) on the extremities, and are at a greater risk of developing pneumonia.
EPIDEMIOLOGY: Before vaccine introduction in 1963 in United States, 130 million cases and 7-8 million deaths were estimated to be due to measles and 95-98% of children were infected Footnote 4 Footnote 6. Endemic in metropolitan centers, measles became epidemic every 2-3 years primarily in late winter and early spring and spread by waves to smaller cities and rural area, where it was more severe Footnote 1 Footnote 7. Mortality declined in the first half of twentieth century due to life quality improvement. In the 1960’s, vaccine introduction allowed substantial reduction of both incidence and mortality due to measles. Resurgence of disease in 1989-1991 was due to low vaccination coverage amongst certain populations in industrialized countries Footnote 4 . Measles is considered eliminated in the Americas and Europe, however occasional outbreaks occur due to imported cases and unvaccinated populations Footnote 6. Measles is still a common disease in developing countries Footnote 1.
INFECTIOUS DOSE: 0.2 units by intranasal spray Footnote 9.
MODE OF TRANSMISSION: Measles can be spread by respiratory droplets and by direct contact with secretions from nose and throat of an infected person Footnote 7 Footnote 8. Direct contact is the primary mode of transmission, and airborne droplet and indirect contact are less common modes of transmission.
INCUBATION PERIOD: 8-12 days Footnote 3.
COMMUNICABILITY: Measles is a highly communicable disease Footnote 3. Patients are infectious from the onset of prodomal symptoms until 2-4 days after rash development, but communicability is higher before rash appearance.
ZOONOSIS: None known Footnote 11, but humans may communicate the disease to non-human primates.
DRUG SUSCEPTIBILITY: Measles virus has been reported to be susceptible to Ribavirin, but it is not currently approved for therapeutic use against measles Footnote 12.
SUSCEPTIBILITY TO DISINFECTANTS: MV is susceptible to povidone iodine, formaldehyde, 1% sodium hypochlorite, 70% ethanol, glutaraldehyde, phenolic disinfectants, peracetic acid, hydrogen peroxide Footnote 13,Footnote 15.
SURVEILLANCE: Monitor for symptoms, microbiological and serological testing for measles virus or anti-measles antibodies Footnote 3.
FIRST AID/TREATMENT: There is currently no treatment for measles other than supportive care. In cases of malnourishment or vitamin A deficiency, vitamin A may be prescribed to help avoid complications Footnote 12.
IMMUNIZATION: There is a trivalent vaccine using live-attenuated virus of measles, mumps and rubella (MMR), but this vaccine requires constant cold for storage and transport, which is a problem in developing countries Footnote 3 Footnote 10. The first dose is given in the first year, and the second at the beginning of schooling (4-6 years of age) to allow full coverage Footnote 6. In Canada, vaccination is also recommended for all people born after 1957, because first generation killed vaccine was poorly immunogenic. Before 1957, most people had contracted measles and are considered immune. Pregnant women should not take MMR Footnote 3.
PROPHYLAXIS: Immunization with live virus vaccine can be given up to 72 hours post-exposure to prevent measles in unvaccinated persons. Passive immunization with measles immunoglobulin (0.25 mL/kg, for a maximum of 15 mL) between 72 hours and 6 days following exposure or in persons for which measles vaccine is contraindicated can be given to prevent or decrease the severity of measles Footnote 3.
LABORATORY-ACQUIRED INFECTIONS: One case of a laboratory acquired infection up to 1974 Footnote 11.
SOURCES/SPECIMENS: MV may be isolated from urine, conjunctiva, nasopharynx, and blood Footnote 18.
PRIMARY HAZARDS: Splashing, accidental parenteral inoculation and droplet exposure of mucous membrane may cause a laboratory-acquired infection Footnote 13.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2 Footnote 19.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 20.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities Footnote 20.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism by autoclave, chemical disinfection, gamma irradiation, or incineration before disposing.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: September 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2011