As rinderpest approaches global extinction, the goal of eliminating measles in Europe this year seems unattainable; why? and what could now be done to hasten its demise?
Microbiologists should be rejoicing this year, which is likely to see the formal announcement of the global eradication of rinderpest, the second disease (after smallpox in the late 1970s) to be exterminated from planet Earth. A devastating plague of cattle herds throughout the world, rinderpest killed up to 90% of infected animals, rendering survivors lethargic and unproductive and thus drastically impairing food production, especially in Africa. Famine and economic depression were often the sequelae when the virus attacked cattle and buffalo crucial to a country's economy. Just over 20 years ago, a widespread outbreak cost Nigeria some $2 billion.
Alas, the one individual most responsible for the extinction of rinderpest, English veterinary microbiologist Walter Plowright, has not lived to witness his final triumph. Plowright, who died on 19 February at the age of 86, introduced the tissue culture rinderpest vaccine (TCRV) that enormously facilitated control and eventual elimination of the disease. There had been previous candidates, but the TCRV developed by a team under Plowright at the East African Research Laboratory at Muguga in Kenya in the 1950s and 1960s was not only highly potent, inducing long-lasting immunity, but also easily administered and relatively cheap. In humanitarian as well as scientific terms, the honours heaped upon Walter Plowright-from a fellowship of the Royal Society in 1981 to the World Food Prize in 1999-were richly deserved.
For microbiologists in Europe, 2010 ought to be seeing a further cause for rejoicing. Five years ago, the European Region of the World Health Organization announced that 2010 was the target date for the elimination of measles from the continent. As with smallpox and rinderpest, long-lasting immunity-a crucial requirement if the goal were to be attained-was achievable by means of several types of vaccine. Both the technical necessities and the political will were firmly assured. Yet the reality is that celebration will almost certainly have to be postponed.
The reason for this disappointment is the suboptimal level of vaccination seen in a small number of European countries. And nowhere is the problem more vividly demonstrated than in minority groups such as those following the teaching of the Austrian "mystic" Rudolf Steiner. Among the tenets of his "anthroposophy" are the avoidance of chemicals in agriculture and the rejection of immunization. Steiner believed that febrile illnesses such as measles and scarlet fever were related to a child's spiritual development. Adherents assert that the use of vaccines (especially measles vaccine) deprives infants of the opportunity to benefit from the experience of having those diseases.
Several papers in recent years (for example, J.S. Alm et al., Lancet 353:1485-1488, 1999, and M. Muscat et al., Lancet 373:383-389, 2009) have illustrated the way in which the ongoing importation and spread of measles virus within minority groups with low vaccination coverage has been hampering efforts to eliminate the disease in Europe. The most conspicuous manifestations of the problem have been outbreaks in anthroposophical communities in the UK, the Netherlands, and Switzerland (B. Hanratty et al., Epidemiol. Infect. 125:377- 383, 2000, E. van Velzen et al., Eurosurveillance 13:pii_18945, 2009 and E. Du Vell et al., J. Epidemiol. Community Health 55:685-686, 2001).
The latest such incident occurred in Austria between March and July 2008, but only re cently, with publication of a formal analysis of the parameters of the outbreak, have the disquieting implications become fully clear. Written by Franz Allerberger and collaborators at the Austrian Agency for Health and Food Safety, Vienna, together with investigators at other centers in both Austria and Germany, the report appears in Epidemiology and Infection (138: 415-425, 2010).
The first indication of the problem was the reporting to the public health authorities in Salzburg province of a cluster of nine laboratoryconfirmed cases of measles among children in a Steiner school in Salzburg city. A week later, a second report detailed a further 35 cases. Then 30 more cases were reported among pupils who attended the school but lived in the neighboring German province of Bavaria. The school was closed, and a full investigation initiated. The eventual total comprised 394 cases, 168 of them linked with the anthroposophic school. The probable source was a child who had visited the school recently from the same sort of school in Switzerland.
Hospitalization was necessary for 10.7% of the children. Fortunately, there were no cases of meningitis or encephalitis, but otitis media occurred in 3.3% of cases and pneumonia in 1.8% of cases.
Enquiries into the vaccination status of children affected showed that 11% of those not belonging to the anthroposophic community had received at least one dose of measles-containing vaccine (MCV). The corresponding figure for cases within the community was a mere 0.6%. "Therefore, low vaccination coverage is likely to be the cause of the rapid spread of measles in the anthroposophic school community," Allerberger and his co-workers write. "The anthroposophic community is known to favor allowing the body to experience certain infections and to oppose vaccination in childhood . . . In this Austrian anthroposophic community, 94% of parents willing to give reasons for a child's unvaccinated status stated that having a measles infection is important for a child's development and has a ‘beneficial strengthening effect upon the child'."
The authors believe that their findings underline the epidemiological significance of minority groups, including anthroposophical communities, in facilitating the circulation of measles virus, and show that inadequate levels immunization in older groups in the general population is jeopardizing the control of measles in Austria. "The suboptimal vaccination coverage also observed in populations of other European counties such as Switzerland, Germany and Italy raises doubts that the goal of measles elimination by 2010 can be achieved."
Anthroposophy is by no means the only source of anti-vaccination sentiment, either historically or today. Even members of the medical profession have played key roles in fostering public hostility to immunization in general or to specific vaccines. The UK is only just beginning to recover from the furor triggered by a suggestion of links between MMR (measles, mumps, rubella) vaccine and intestinal inflammation and autism occasioned by a notoriously poor paper in The Lancet (351:637-41, 1998) by Andrew Wakefield and others at the Royal Free Hospital, London. Following publication of the paper, parents began to reject immunization, and recent measles outbreaks have been attributed to the resulting low level of protection among young children. Earlier this year, after a decade in which the paper's inadequacy was thoroughly exposed, The Lancet formally withdrew the Wakefield paper.
Aside from aberrations of this sort, most countries have tried, sometimes struggled, to accommodate principled objections to immunisation. Some of those with mandatory vaccination for school attendance, and some states within the United States have permitted religious or philosophical exemptions. The current scenario of measles in Europe shows that such tolerance can come under severe strain as communities move towards the total elimination of an infectious disease, but find the final stages thwarted by opponents of immunization. While the subject has attracted media comments in the countries affected, there seem to have been few if any attempts to bring together the opposing voices in a debate designed to explore the issues more profoundly than newspaper headlines allow. The World Health Organization is well respected for its role in global health promotion. Steinerian schools and clinics, in both Europe and the United States, have a reputation for helping mentally handicapped children and others with special needs. Surely, there is enough goodwill on both side to support a serious attempt at reconciliation and mutual learning?