Measles outbreaks

A live vaccine strain of measles (Chapter 15) was introduced in the USA in 1962 and to the UK in 1968. A single injection produces high-level immunity in over 95% of recipients. Moreover, since the vaccine induces immunity more rapidly than the natural infection, it may be used to control the impact of measles outbreaks. The measles virus cannot survive outside ofan infected host. Widespread use ofthe vaccine therefore has the potential, as with smallpox, of eliminating the disease worldwide. Mass immunization has reduced the incidence of measles to almost nil, although a 15-fold increase in the incidence was noted in the USA between 1989 and 1991 because of poor compliance. 

Wakefield and Montgomery subsequently raised doubts about the adequacy of the evidence that secured the license for MMR vaccine (63). Particularly in view of the immunosuppressive properties of the measles virus, they suggested that there is a potential for adverse interactions between the component live viruses. They therefore proposed that spaced monovalent measles, mumps, and rubella immunization should replace the use of the combined MMR vaccine. The continuing publications of Wakefield led to reduced MMR coverage in some parts of the UK and to well-publicized concerns about the potential for measles outbreaks among primary school entrants. In an editorial in the British Medical Journal, Elliman and Bedford replied to Wakefield s paper (64). They... 

Propagated outbreaks of infection relate to the direct transmission of an infective agent from a diseased individual to a healthy, susceptible one. Mechanisms of such transmission were described in Chapter 4 and include inhalation of infective aerosols (measles, mumps, diphtheria), direct physical contact (syphilis, herpes virus) and, where sanitation standards are poor, through the introduction of infected faecal material into drinking water (cholera, typhoid). The ease oftransmission, and hence the rate of onset of an epidemic (Fig. 16.3) relates not only to the susceptibility status, and general state of health of the individuals but also to the virulence properties of the organism, the route oftransmission, the duration of the infective period associated with the disease. 

A second dose of MMR is recommended for adults who 1) have been recently exposed to measles or are in an outbreak setting 2) have been previously vaccinated with killed measles vaccine 3) have been vaccinated with an unknown type of measles vaccine during 1963-1967 4) are students in postsecondary educational institutions 5) work in a health-care facility or 6) plan to travel internationally. 

At present, vaccines are available for several serious viral infections, including polio, smallpox, rabies, measles, mumps, rubella, hepatitis A and B, and influenza. In some situations, vaccination against certain viral infections is routine. For instance, schoolchildren must periodically show evidence of polio, measles, and other vaccinations according to state and local laws. In other cases, vaccines are administered prior to potential exposure to the virus or in high-risk groups. Influenza vaccinations, for example, are often administered to elderly and debilitated patients during seasonal influenza outbreaks.75,109... 

Three cases within a week in the same neighborhood means that the disease is spreading. The doctor fears an epidemic is under way. She immediately calls city health officials and tells them the problem. The health commissioner faxes a request to the Centers for Disease Control (CDC) in Atlanta for ten thousand doses of measles vaccine. The plan is to initiate a crash program of vaccinations in the immediate neighborhood so that spread of the disease will be damped. Infected children will be quarantined after the outbreak is contained, an educational program will be initiated to alert parents to the abiding... 

Dourado 1, Cunha S, Teixerra MG, Farrington CP, Melo A, Lucena R, Barreto ML. Outbreak of aseptic meningitis associated with mass vaccination with a urabe-containing measles-mumps-rubella vaccine implications for immunization programs. Am J Epidemiol 2000 151(5) 524-30. 

The measles vaccine is administered subcutaneously as a0.5-mL dose in the arm (or in the thigh if the patient is younger than 15 months of age). The vaccine is administered routinely for primary immunization to persons 12 to 15 months of age, usually as the MMR vaccine. The measles vaccine is not administered earlier than 12 months (except in certain outbreak circumstances) because persisting maternal antibody that was acquired transplacentally late in gestation can neutralize the vaccine virus before the vaccinated person can mount an immune response. A second dose of MMR is recommended when... 

Respiratory syncytial virus is a member of the paramyxovirus family, a genera that includes metapneumovirus, measles and Newcastle disease viruses [21]. The discovery of RSV as a human pathogen began with an outbreak of coryza in chimpanzees, documented in 1956, which was quickly followed by the identification of the vims in infants presenting with bronchiolitis and pneumonia [22-25]. Epidemiological studies have established the patterns of outbreaks of RSV... 

As UV-B radiation weakens the immune system, the decreasing ozone concentration in the stratosphere is expected to cause increased outbreaks of measles, chicken pox, malaria, leishmaniasis, tuberculosis and leprosy. The immune depressing effects of UV-B radiation will be felt most severely in the Himalayan regions such as Nepal, Bhutan, India and the Tibetan plateau in China. Due to the high altitudes, the population of these regions is already exposed to greater amounts of ultraviolet light. 

Very commonly, an infection precipitates kwashiorkor in children whose nutritional status is inadequate, even if they are not yet showing signs of malnutrition. Indeed, paediatricians in developing countries expect an outbreak of kwashiorkor a few months after an outbreak of measles. 

In regions where a disease, such as measles, appears season after season, it is advised that healthy susceptible people be vaccinated before they are exposed, and before there is a disease outbreak, because (1) it takes time to produce an active immunity, and (2) some people may be about to be infected with the disease. Descriptions of the most common types of vaccinations or shots follow. 

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