Communicable disease report. CDR review最新文献

An outbreak of gastroenteritis caused by campylobacter infection was identified in May 1995 in a residential school in Gloucestershire for children with special needs. Eight primary and four secondary cases were identified, mostly confined to one house in the school; faecal specimens from three cases grew Campylobacter jejuni. A retrospective cohort study showed that drinking pasteurised milk from bottles with damaged tops was associated with illness in primary cases (p = 0.01). Bird pecking of milk bottle tops probably accounts for several thousand cases of human campylobacter infections during May and June each year in England and Wales. Milk bottle containers for doorstep delivery should be resistant to contamination by birds.

Campylobacter has been the commonest enteric pathogen isolated from humans in England and Wales since 1981, but few cases are linked to outbreaks. Twenty-one general outbreaks of campylobacter infection in England and Wales were reported to the PHLS Communicable Disease Surveillance Centre from 1992 to 1994. Seven hundred and six people were affected, nine cases were admitted to hospital, and no deaths were reported. The mean attack rate was 46.2% (SD 25.7%) and the mean duration of illness was 11 days (range 3 to 61 days). Outbreaks occurred throughout the year and throughout England and Wales. Infection in 18 outbreaks was reported to have been transmitted by food or water: eight were related to food (particularly poultry), six to contaminated water from a private water supply, and four to raw or inadequately pasteurised milk. General outbreaks of campylobacter infection appear to be unusual and should be investigated thoroughly. The new PHLS Campylobacter Reference Unit will assist in the identification of outbreaks of campylobacter infection and help to identify the risk factors associated.

The incidence of measles in England and Wales has fallen since the national vaccination campaign in November 1994, in which 92% of children aged 5 to 16 years were vaccinated. A total of 148 confirmed cases with onsets in the 18 months from January 1995 to June 1996 have been ascertained. Notified cases did not provide a reliable measure of incidence: 11,343 suspected cases were notified in the same period, 6426 (57%) of whom were tested for salivary antibody. Only 90 (1.4%) of cases tested were confirmed. Many confirmed cases occurred in small clusters; 12 imported cases were identified. The pattern of small, local clusters is what would be expected from the introduction of imported cases into a population with herd immunity. Serological surveillance showed that the campaign produced a significant fall in the proportion of 5 to 16 year old children with low levels of measles antibody: the proportion with levels < 50 mIU/ml fell from 8.4% to 2.1%; the proportion with levels < 100 mIU/ml fell from 15.7% to 6.6%. About 15% of 2 to 4 year old children had antibody levels < 100 mIU/ml before and after the campaign. The addition of a routine second dose of measles vaccine (as measles, mumps, and rubella vaccine) to the vaccination schedule will provide another opportunity to immunise these children before they start school. The two dose vaccination programme should maintain the herd immunity of the population and the elimination of endemic measles transmission.

The national immunisation campaign carried out in the United Kingdom in November 1994 was designed to give children aged 5 to 16 years of age a single dose of a combined measles and rubella vaccine. Its main objective was to prevent an epidemic of measles predicted in school age children. The rubella component of the vaccine was included in order to reduce the high level of susceptibility to rubella in young adult males and thus reduce the risk of transmission from this group to pregnant women. Susceptibility to rubella in children aged 5 to 16 years has fallen from 15.7% to 3.4% since the measles and rubella campaign. Despite this the incidence of laboratory confirmed rubella rose substantially in 1996, largely on account of cases among males aged 17 to 24 years, who were not vaccinated in the 1994 campaign and about 16% of whom are susceptible. The impact of the resurgence on the incidence of infection in pregnancy has been relatively limited, due to the low level of susceptibility in the antenatal population (2% in nulliparous and 1.2% in parous women for 1994/5). No cases of congenital rubella arising from administration of measles and rubella vaccine during the campaign have been identified. The numbers of babies born with congenital rubella and terminations of pregnancy for rubella arising from the 1996 resurgence are expected to be similar to those that followed the 1993 resurgence. The reduction in susceptibility in future cohorts of young men who received measles and rubella vaccine in the 1994 campaign should prevent future resurgences after the year 2000. If a second dose of measles, mumps, and rubella (MMR) vaccine had not been introduced, susceptibility levels in the school age population would have risen to about 12% in the future. The effect of the second dose of MMR vaccine introduced for children aged 4 to 5 years in October 1996 will be assessed through serological surveillance.

Sentinel surveillance in general practice and laboratory reports to the PHLS Communicable Disease Surveillance Centre show that the incidence of mumps has fallen to very low levels since vaccination against measles, mumps, and rubella was introduced in 1988. Hospital admissions for mumps show a 92% decline compared with the prevaccination era, to a rate of 0.2 per 100,000 population per year. Serological surveillance has shown an increase in the proportion of school age children who have no detectable antibody to mumps, which is consistent with the reduction in mumps virus transmission. The proportion of children aged 11 to 15 years with no detectable antibody is expected to peak at 19% in 1997. Mathematical models suggest that this increase in susceptibility is unlikely to allow a large resurgence of mumps in the short term but that school outbreaks may become more common. Outbreaks in universities and military establishments are possible in the medium term. Analysis of efficacy data for mumps vaccine indicates that mumps is unlikely to be eliminated with a single dose of vaccine at current coverage rates. A second dose of vaccine, which is now being offered to preschool children, will reduce morbidity and should eventually eliminate mumps if coverage is high enough.

Two hundred and nine culture confirmed cases of meningococcal disease were reported in the Republic of Ireland in 1995, using a new laboratory based surveillance system. The reported rate of 5.9/100000 population is one of the highest in western Europe, but the rate differed widely between regions. Fifty-three per cent of cases were female. Half of the cases occurred in four months (January, February, March, and December). Nineteen cases (9%) died. The highest age specific incidence was in infancy (under 1 year). Infections with serogroup B accounted for 105 cases (54%) and serogroup C 87 cases (45%). We estimate that up to 30% of cases of meningococcal disease may be preventable when conjugate meningococcal group C vaccines become available, but cost benefit analyses will be required to determine how they should be employed.

Guidance on the management of clustered cases of meningococcal disease has been revised following a review of the clusters that occurred in England and Wales between 1 April 1995 and 31 March 1996. Public health action is indicated for confirmed and probable cases but not in response to possible cases. The importance of microbiological confirmation is re-emphasised. Intervention is recommended for defined target groups when two or more confirmed or probable cases occur in a preschool group or school within a four week period. We present a framework to assist in the management of clusters of invasive serogroup C infections in larger and less defined communities.

Neisseria meningitidis group C type 2b, P1.2, P1.5 caused an outbreak of four cases, two of whom were members of an agricultural college in Devon, and two outside contacts of students who were documented carriers of the outbreak strain. The identification of the outbreak was made more difficult by the fact that none of the three cases first linked with the college was culture positive and indeed only one of these was actually a member of the college. Carriage of the outbreak strain was significantly associated with residence in college and enrollment on one particular course. The question was raised of whether in outbreaks of this type control measures should be extended beyond the confines of the affected institution.