Communicable disease report. CDR review最新文献

Information about the epidemiology of meningococcal disease case clusters and the risk of further cases is sparse. Data on clusters in household and educational settings from 1 January 1993 to 31 March 1995 was requested from consultants in communicable disease control in England and Wales through a retrospective postal survey. Ninety-three per cent (122/131) responded. Of the 114 cases in 45 reported clusters, 77 (67.5%) were microbiologically confirmed. The case fatality rate in index cases was higher than in associated cases (18.2% vs 4.5%; p = 0.02). Five out of 11 clusters in household settings consisted only of index and co-primary cases. No further cases occurred within two weeks after giving chemoprophylaxis to household contacts. The relative risks of further cases in the week after the index case arose were estimated to be 1200 for contacts in the household, 160 in secondary schools, 60 in primary schools, 1.8 in universities/colleges, and 0 in nurseries. Between seven and 30 days the relative risks were lower; 150 in households, and between 0 and 13 in all other settings. Beyond 30 days, the relative risk in the household setting was 8 and lower than this in all other settings. The absolute risk of further cases in the month following the index case was calculated as 210 per 100,000 in household members, 7-10/10(5) in pupils at the same school, and 0.6/10(5) in students at the same university or college. The current policy in England and Wales to recommend chemoprophylaxis for household members may prevent half of the further cases in this setting. Raised awareness may have contributed to the lower case fatality rate among household contacts who developed meningococcal disease, but the number of co-primary cases observed should prompt urgent enquiries about current illness in household contacts of index cases. The relative risk of further cases in preschool groups was low and apparently unaffected by changes in chemoprophylactic policy. The relative risk in school settings was raised in the month following a case, but the absolute risk was still low. Further study to quantify the risk in university settings is needed.

An outbreak of food poisoning due to Escherichia coli O157 phage type 2 Vero cytotoxin 2 affected 26 people in southern counties of England in May and June 1995. The organism was isolated from faecal specimens from 23 patients, 16 of whom lived in Dorset and seven in Hampshire. Isolates were indistinguishable by phage typing, Vero cytotoxin gene typing, restriction fragment length polymorphism, and pulsed field gel electrophoresis. Three associated cases, linked epidemiologically to the outbreak, were confirmed serologically by detection of antibodies to E. coli O157 lipopolysaccharide. Twenty-two of the 26 patients were adults: four were admitted to hospital with haemorrhagic colitis. Four cases were children: two were admitted to hospital with haemolytic uraemic syndrome (HUS). There were no deaths. Although E. coli O157 was not isolated from any food samples, illness was associated with having eaten cold meats in sandwiches bought from two sandwich producers, in Weymouth and in Portsmouth. Both shops were supplied by the same wholesaler, who kept no records and obtained cooked meats from several sources in packs that did not carry adequate identification marks. It was, therefore, impossible to trace back to the original producer or to investigate further to determine the origin of contamination with E. coli O157. To protect the public health it is essential that all wholesale packs of ready-to-eat food carry date codes and the producer's identification mark. Detailed record keeping should be part of hazard analysis critical control point (HACCP) systems and should be maintained throughout the chain of distribution from the producer to retail outlets.

This report summarises information collected for the surveillance of influenza in England and Wales during the winter of 1996/97. Consultations for 'influenza and influenza-like illness' with sentinel general practitioners in England and Wales began to increase towards the end of November and peaked at the start of January. In England, consultations for 'aggregated respiratory disease' (ARD) began to increase a little earlier, perhaps as a result of increased respiratory syncytial virus activity, but also peaked in early January. Influenza A (H3N2) viruses were first detected in early October, but rarely until November, and activity peaked in early January, coinciding with the peak in consultations for flu-like illness. A few influenza B viruses were detected in late November and early December, and substantial activity was recorded in mid-January. Approximately equal numbers of influenza A(H3N2) and B viruses were identified over the winter as a whole, and circulating strains were antigenically similar to those included in the vaccine for 1996/97. Although influenza activity was 'moderate' in terms of consultations and laboratory confirmed infections, a large peak in death registrations occurred at the same time as influenza A(H3N2) virus activity peaked. The number of deaths during the winter was similar to that seen in 1989/90, when the last severe influenza epidemic occurred in England and Wales.

A community outbreak of infection with Vero cytotoxin producing Escherichia coli O157 (VTEC 0157) occurred in a small area of north west England in 1996. An outbreak control team was established to investigate the outbreak and implement control measures. Nine people developed symptomatic infections with VTEC O157, and a further three were found to be excreting the bacteria. All were infected with the same genotype of VTEC O157. Three children under 5 years of age and one adult were admitted to hospital. One child developed haemolytic uraemic syndrome. All cases recovered. All primary cases had consumed milk from a particular farm dairy. No other common foods were identified. The farm dairy had a faulty pasteuriser and the potential for post pasteurisation contamination existed. VTEC O157 was isolated from a milk sock specimen and from two cows, but these strains differed from that infecting the cases. All local doctors and the public were alerted and advised about preventative measures. Distribution of unpasteurised milk from the farm was discontinued as was the sale of pasteurised milk when the faulty pasteuriser was discovered. A replacement pasteuriser was installed and checked before milk was released for human consumption. No conclusive evidence of the origin of this outbreak was found, but the farm was the most probable source. The investigations raised concerns about the distribution of VTEC O157 colonised dairy cattle, the natural history of such colonisation, the effectiveness of pasteurisation with respect to the elimination of VTEC O157, and the effectiveness of current legislation for the prevention and control of milkborne infection.

A profile of sexually transmitted diseases (STDs) and HIV infections among teenagers in England and Wales was obtained from reports of newly diagnosed STDs among teenagers attending genitourinary medicine (GUM) clinics in 1995, laboratory reports of newly diagnosed HIV infections between 1985 when reporting began and the end of 1995, and the prevalence of HIV (unlinked anonymous programme) among teenagers attending genitourinary medicine clinics and antenatal clinics in 1994 and 1995. STD reports were analysed by sex, age group, and place of residence of patients--whether in the NHS Thames regions or elsewhere in England and Wales. High rates of STDs were reported in teenagers, particularly in girls. The incidences of gonorrhoea, chlamydia infection, and first attack genital wart infections were higher in teenage girls than in any other age group. Boys under 16 years of age had substantially higher rates of infection with all STDs in the Thames regions than elsewhere. Rates of gonorrhoea in teenagers of both sexes in the Thames regions were more than twice those in the rest of the country. Infection rates for genital herpes, and chlamydia in girls, were also higher in the Thames regions, although the geographical differences were less marked. The seroprevalence of HIV among heterosexual teenagers was very low. In contrast, 226 HIV infections among teenage boys had probably been acquired through sexual intercourse with other males. Unlinked anonymous testing revealed HIV antibody in 7.5% of routinely collected serology specimens taken from teenage homosexual or bisexual males attending GUM clinics in London. The high rates of STDs among teenage girls and all teenagers in the Thames regions make these groups a high priority for sexual health promotion, with special consideration given to homo/bisexual male teenagers. Detailed surveillance of risk factors for STDs, and further studies of teenage sexual behaviour will help to effectively target resources to improve the sexual health of teenagers in England and Wales.

Official government statistics and serological laboratory data provide limited information about the incidence of leptospirosis in the Republic of Ireland. The mean annual notified incidence in the Republic of Ireland from 1985 to 1996 was 1.3/million. The incidence according to hospital discharge diagnosis was higher at 4.9/million. One hundred and seventy-five serologically confirmed cases of leptospirosis were reported from 1986 to 1996, giving a mean annual incidence of 4.5/million. The true incidence of leptospirosis in the Republic of Ireland is probably higher, as hospital discharge data are incomplete and full serological testing was not always performed. Our data indicate that leptospirosis is an underestimated public health problem with only 26% of cases being notified. A national communicable disease surveillance centre in the Republic of Ireland would facilitate better monitoring and understanding of this disease.

An outbreak of eight cases of cryptosporidiosis in Hampshire over a period of eight weeks in the summer of 1996 was linked to use of one swimming pool. Cryptosporidial oocysts were not isolated from samples of backwash, but the presence of enterobius ova indicated faecal contamination and a case control study including the first four primary cases suggested an association with immersion in the pool. Even in small outbreaks case control studies can provide useful supportive evidence as to the possible source of infection.

A retrospective cohort study was performed to examine the extent and clinical significance of misclassification associated with using the current United States AIDS case defining category of an initial CD4 count < or = 200 cells x 10(6)/l (< or = 200) compared with a definition requiring two consecutive counts below this level. The main outcomes examined were the probability of subsequent CD4 counts > 200 x 10(6)/l (> 200) and progression times to AIDS and death. Of the 2025 predominantly male homosexual HIV-positive patients attending two hospital based HIV clinics with initial CD4 cell counts < or = 200, 1524 (75%) subsequently had consecutive counts < or = 200, but only half did so at the next CD4 count. Ten per cent had either no further or only non-consecutive counts < or = 200, and 15% had only one CD4 count available for analysis. The cumulative proportion of patients with a CD4 count > 200 at one year after a first count of < or = 200 was about twice (39%) that observed among the subgroup with at least two consecutive counts < or = 200 (19%). The times from the initial counts of < or = 200 to AIDS and death were also shorter by six months and two months, respectively, in the subgroup with two or more consecutive counts < or = 200. A significant proportion of patients will be prematurely classified as having a CD4 cell count < or = 200 if a single CD4 count below this level is accepted. A definition of two consecutive counts < or = 200 should be adopted in preference to a single count < or = 200 for natural history studies and clinical trials, in which precise estimates of the time to or from a defined CD4 threshold are important. In surveillance programmes, however, such an approach may be impractical because of missing or infrequent serial CD4 counts, although adjustments can be made based on these estimates of premature misclassification.

Two hundred and one cases of legionnaires' disease were reported to the PHLS Communicable Disease Surveillance Centre in 1996. Twenty-four cases (12%) were known to have died. One hundred and one cases were associated with travel, either abroad or in the United Kingdom. Two cases acquired infection in hospital, the smallest number ever reported, and the remaining 98 were presumed to have acquired infection in the community. Fifty-five (27%) of the 201 cases were linked to outbreaks or clusters and the remaining 146 (73%) were reported as single cases. Six outbreaks were associated with industrial premises. Twenty-two of the travel associated cases were part of three travel outbreaks and six clusters. The proportion of cases diagnosed by detection of urinary antigen has continued to increase and in 1996 this method of diagnosis was used for 43% of the cases.

The implementation of a selective neonatal BCG immunisation policy adopted in south east London boroughs of Lambeth, Southwark, and Lewisham in 1992 has been audited. A survey conducted 18 months after the policy was implemented showed that only 11% of infants identified as eligible for neonatal BCG immunisation had been immunised. The results of the survey were fed back to neonatal units, which were encouraged to improve access to BCG immunisations for eligible infants. A second survey 17 months later showed that 14% of eligible infants had been immunised. Difficulties in applying complex selection criteria, rapid turnover of trained staff in acute units, and short neonatal stay were thought to contribute to the poor uptake of the selective programme delivered in the neonatal units. A community based BCG immunisation service has been commissioned to improve uptake.