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Eurosurveillance Weekly: Thursday 1 March 2001. Volume 5, Issue 9
Contents:
1.
2.
3.
Foot and mouth disease outbreak does not threaten human public health
Evidence for rotavirus vaccine risk
Further support for the safety of MMR vaccine
Animal foot and mouth disease outbreak does not threaten public health
The outbreak of foot and mouth disease (FMD) in pigs and cattle in the United Kingdom (UK) has raised
the question whether the disease poses a risk to humans. Very few human infections have been
documented, despite regular exposure of humans to infection in livestock throughout the world and
those few infections that have been reported have resulted in mild self-limiting illness(1). Human to
human transmission has never been reported and FMD is not transmitted to humans through the food
chain. I.e.this disease is not a public health threat.
Foot and mouth disease is a highly infectious disease of animals (predominatly cattle, sheep, pigs, and
goats) and spreads rapidly if uncontrolled. It is caused by a virus of the family Picornaviridae, genus
Aphthovirus, of which there are seven main types. The current outbreak in the UK is due mainly to the
pan asiatic type O (2). The disease presents in animals with acute fever, followed by the development of
blisters chiefly in the mouth and on the feet of the animal. Infected animals secrete numerous virus
particles in saliva, faeces, urine, milk, and semen before clinical signs appear. Unless eradicated
immediately economic losses can be huge.
The overall risk of human infection is extremely small. Among the extremely rare documented cases,
symptoms have been mild and self-limiting, mainly uncomfortable tingling blisters on the hands (3), but
also fever, sore throat, and blisters on the feet and in the mouth and on the tongue. This can result in a
painful mouth and difficulty in eating, drinking and talking. Human cases have usually recovered a week
after the last blister formation. There is no evidence of person to person spread, or of transmission to
humans through the consumption of meat, or pasteurised milk. Foot and mouth disease is not known to
be hazardous to humans and animals through mains drinking water.
The few proven cases of foot and mouth disease in man have occurred in several countries in Europe,
Africa, and South America. The last human case confirmed in Britain occurred in 1967 during the last
epidemic (4). There were no human cases during the 1981 outbreak. Foot and mouth disease must not
be confused with the human disease called "hand, foot and mouth" disease. This is an unrelated and
usually mild viral infection principally of children and due to an entirely different virus (a human
enterovirus, most commonly coxsackie A) (5).
By far the most important aspect of the present outbreak is to prevent animals from becoming infected,
and to prevent further animal to animal transmission. Information about the outbreak and foot and
mouth disease in animals in the UK can be found on the Ministry of Agriculture Fisheries and Food
(MAFF) website (www.maff.gov.uk/animalh/diseases/fmd/qa1.htm).
The preferred method of control is a policy of slaughter of infected animals and those animals exposed
to infection. Movement restrictions are also put in place to help contain the disease. People who handle
infected animals can minimise any possible risk to themselves by maintaining good personal hygiene
(such as handwashing and facewashing) and by wearing protective clothing if appropriate and practical
.(2)
References:
1. Bauer K. Foot-and-mouth disease as zoonosis. Arch Virol 1997; 13 (suppl): 95-7.
2. Ministry of Agriculture Fisheries and Food (MAFF).
www.maff.gov.uk/animalh/diseases/fmd/qa1.htm
3. Pilz W, Garbe HB. Weitere Fälle von Maul- und Klauenseuche - MKS-Infektionen beim
Menschen. Zbl Bakt I Orig 1965; 198: 154-157
4. Armstrong R, Davie J, Hedger RS. Foot-and-mouth disease in man. BMJ 1967; iv: 529-30.
5. Chin J (editor). Coxsackievirus diseases. In: Control of communicable diseases manual. 17th
edition. Washington DC: American Public Health Association, 2000: 129-31.
Reported by Henry Prempeh ([email protected]) and Berit Muller ([email protected]), Public
Health Laboratory Service Communicable Disease Surveillance Centre, London, England.
Evidence for rotavirus vaccine risk
The tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV) was withdrawn from the United
States primary immunisation schedule in 1999, after a larger than expected number of infants given the
vaccine were reported to have developed intussusception (a form of bowel obstruction in which part of
the bowel prolapses into a more distal section) (1). The results of a case control study and a case series
analysis used to investigate the possible association of the vaccine with intussusception were published
in the New England Journal of Medicine last week (2).
Data on 429 infants (1 to 12 months) with intussusception and 1763 matched controls were collected in
19 states between 1 November 1998 and 30 June 1999 (2). Significantly more infants with
intussusception (74/429; 17%) than controls (226/1763; 13%) had received RRV-TV. The risk of
intussusception was increased from three to 14 days after the first of the three doses of RRV-TV.
Analysis of a case series of 432 infants with intussusception found an incidence rate ratio of 29.4 for
days 3 to 14 after a first dose, with a smaller increase in risk after the second dose. The investigators
estimate that one case of intussusception attributable to the vaccine would occur for every 4670 to 9474
infants vaccinated (2).
Rotavirus infection is the commonest cause of severe gastroenteritis in children under 5 years of age,
responsible for over 500 000 deaths in developing countries each year (3). It was noted recently that,
among children under 5 years of age, 12 children per 1000 in Ireland are admitted to hospital for
rotavirus infection each year, compared with 6/1000 in Finland, 5/1000 in the United Kingdom, and
3.5/1000 in the United States (4,5). An estimated 3.5 million cases occur each year in the United States,
leading to 500 000 office visits, 50 000 admissions to hospital, and 20 deaths (2).
The authors say that the strength, timing, and specificity of the association between RRV-TV and
intussusception are evidence of causality (2).They note, however, that the risk of admission to hospital
for intussusception attributable to RRV-TV (if the US vaccination programme had been continued)
would be far lower than the rate of admission to hospital for the rotavirus infection it was intended to
prevent. However a difficulty is that rotavirus only rarely results in deaths in industrialised countries
whilst intussusception has a significant mortality in infants. A vaccine against rotavirus remains highly
desirable, but a better safety profile is needed.
References:
1. CDC. Withdrawal of rotavirus vaccine recommendations. MMWR Morb Mortal Wkly Rep 1999;
48: 1007. (http://www.cdc.gov/mmwr//preview/mmwrhtml/mm4843a5.htm)
2. Murphy TV, Gargiullo PM, Massoudi MS, Nelson DB, Jumaan AO, Okoro CA, et al.
Intussusception among infants given an oral rotavirus vaccine. N Engla J Med 2001; 344:
564-72. (http://www.nejm.com/content/2001/0344/0008/0564.asp)
3. Miller MA, McCann L. Policy analysis of the use of hepatitis B, Haemophilus influenzae type b-,
Streptococcus pneumoniae-conjugate and rotavirus vaccines in national immunization
schedules. Health Economics 2000; 9: 19-36.
4. Lynch M, O’Leary J, Cryan B. Rotavirus in Ireland:1997-1999. Epi-Insight 2001; 2(2): 2-3.
(http://www.ndsc.ie/epi_insight/0102ei.pdf)
5.
Handysides S. Surveillance of rotavirus infection in Ireland, 1997-9. Eurosurveillance Weekly
2001; 5: 010215 (http://www.eurosurv.org/2001/010215.htm)
Reported by Stuart Handysides ([email protected]), Eurosurveillance editorial office.
Further support for the safety of MMR vaccine
A paper in last week’s BMJ shows that the incidence of autism in children in the United Kingdom (UK)
aged 2 to 5 years rose sevenfold between 1988 and 1999, while the uptake of measles, mumps, and
rubella (MMR) vaccine remained stable and high (over 95%) (1). The paper provides valuable evidence,
at a time when the uptake of MMR vaccine in the UK at 2 years of age has fallen to 88% (2), and when
UK news media have focused on an alleged link between MMR and the development of autism and
Crohn’s disease (3).
The BMJ paper describes a time trend analysis of data from the UK general practice research database
(1). Three hundred and five children aged 12 years or under (254 male), diagnosed with autism
between 1988 and 1999, were identified. The yearly incidence rose from 0.3 per 10 000 person years in
1988 to 2.1/10 000 person years in 1999. The peak ages at which the diagnosis was made were 3 and
4 years. Data from consecutive annual birth cohorts of boys born from 1988 to 1993 showed that the
four year cumulative incidence (risk) of a first recorded diagnosis of autism at the age of 2 to 4 years
rose from 8/10 000 for boys born in 1988 to 29/10 000 for boys born in 1993. The coverage of and age
at MMR vaccination was similar to that in the population as a whole.
The authors note that MMR is given first at about 15 months of age, and that autism is usually
diagnosed at or after 2 years (1). If MMR vaccine was a major factor in the increasing incidence of
autism, they say, the risk of autism in successive birth cohorts would be expected to plateau within a few
years of full vaccine use. They found no such relationship.
References:
1. Kaye JA, Melero-Montes M del M, Jick H. Mumps, measles, and rubella vaccine and the
incidence of autism recorded by general practitioners: a time trend analysis. BMJ 2001; 322:
460-3. (http://www.bmj.com/cgi/content/full/322/7284/460)
2.
CDSC. COVER programme: July to September 2000. Commun Dis Rep CDR Wkly [serial
online] 2001 [cited 25 January 2001]; 11(4): immunisation. Available from
<http://www.phls.co.uk/publications/CDRelectronic/CDR weekly/CDR
Weekly/pages/immunisation.html>
3. Ramsay M, Nicoll A. Update on the MMR vaccine controversy in the UK. Eurosurveillance
Weekly 2001; 5: 010125 (http://www.eurosurv.org/2001/010125.htm)
Reported by Stuart Handysides ([email protected]), Eurosurveillance editorial office.