Search

An epidemic of salmonellosis due to Salmonella enteritidis phage type 4 (PT4), a rise in Campylobacter enteritis, the detection of foodborne transmission in some cases of listeriosis and a large outbreak of botulism in north-west England and Wales were much publicized events in foodborne infectious disease in Britain in 1989. However, other changes took place in the 1980s which attracted less public attention; outbreaks of viral foodborne disease became more common, haemorrhagic colitis was first recorded, yersiniosis and infections caused by Aeromonas spp. increased, cryptosporidiosis and giardiasis came into prominence, and the major foodborne diseases of the past remained rare and usually imported. This article describes the surveillance of foodborne disease and reviews briefly these recent changes with particular reference to England and Wales, under four main headings: increasing foodborne infections, emerging foodborne infections, foodborne intoxications and ‘old’ foodborne diseases, updating a previous review (Galbraith et al., 1987).

SUMMARY There Were 34 outbreaks of water-borne disease recorded in the UK between 1937 and 1986, comprising over 11794 cases and at least six deaths. A total of 21 outbreaks were due to public water supplies, 11 of them contaminated at source; in eight of these 11 the water was unchlorinated or defectively chlorinated. None of the six reported deaths was due to contamination of public supplies at source. About 1000 cases of gastro-intestinal illness were caused by consumption ofafoods, particularly milk and canned nicats, that had been contaminated by polluted water during processing. Shellfish harvested from pollutcd cstuarics gave rise to increasing numbers of outbreaks of viral gastroenteritis and hepatitis A. The recreational use of water was associated with about 400 serious infections and probably many minor illnesses. Sonie hospital infections may have hecn derived from the potable water supply. A total of 14 outbreaks of legionnaires' disease and eight of humidifier fever were associated with water in buildings. The future control of water-borne and waterassociated disease demands not only continued vigilance in the water industry but closer collaboration between public health doctors and water engineers and scientists.

Summary Analyses of death certificates, hospital discharges and deaths, notifications and laboratory reports of teatnus in England and Wales show that the incidence and death rates from the disease declined over the 50 years 1930-79. In 1979 there were five deaths due to tetanus but probably between 80 and 100 cases. The incidence is now highest in people aged over 65 years, in whom death rates are also highest, and in young males aged 15–44 years.

In England and Wales between 1951 and 1980 233 reported outbreaks of communicable disease attributed to milk or dairy products affected nearly 10 000 people, of whom four died. Tuberculosis and brucellosis have been controlled, but milk-borne outbreaks of salmonellosis and campylobacter enteritis due to raw or defectively pasteurised milk are common and may be increasing in number. Universal heat treatment of milk is an effective preventive measure, and it is regrettable that the continued sale of untreated milk is to be permitted in England and Wales.

The development of the British public health services is briefly reviewed and it is suggested that two types of epidemiologist (Community Physician) are necessary in each locality: one concerned with medical administration and health care planning-the medical administrator, and the other with the prevention of disease-the clinical epidemiologist. A new nation public health service is proposed to revive disease prevention with four main features: (1) A district Clinical Epidemiologist who is a member of the district department of community medicine with responsibility for prevention but with no district administrative duties. (2) A District Epidemiology Unit comprising other appropriate staff. (3) National specialist epidemiology units within the NHS with service roles to support and coordinate the District Clinical Epidemiologists. (4) A national authority within the NHS with responsibility for prevention and for administering the national specialist units.

SUMMARYIn the UK surveillance of AIDS and HIV infection is based on routine reporting systems. Whilst attempts are made to ensure that AIDS data are as complete as possible, numbers of reports fluctuate from month to month for reasons which are described. In 1986 there was an increase in death certificates naming AIDS as a cause of death in patients who were not identifiable in the surveillance data. More active surveillance is now undertaken in order to minimize this and other possible discrepancies.It is probable that most cases of AIDS are reported and therefore these data can be used to describe trends in the epidemic by ‘risk group’. Laboratory reports of HIV antibody-positive tests could give an earlier indication of trends because of the long incubation period of AIDS. But these laboratory data are difficult to interpret because they represent an incomplete and biased sample of all positive persons.AIDS cases are still being reported at a rate which is increasing approximately exponentially. Short-term predictions are presented showing a growth in the epidemic which is consistent with previously published predictions. Most cases are in the homosexual risk group. New asymptomatic homosexual patients with HIV antibody are still being identified.The epidemic of AIDS in haemophilia patients should be of finite size although new cases of AIDS are likely to continue to be diagnosed for several years. AIDS due to blood transfusion given in the UK before donor screening appears to be a much smaller epidemic. The epidemic in drug abusers is increasing. Heterosexually acquired AIDS and HIV infections are being reported in small but increasing numbers.

Summary The paper describes the work of the Public Health Laboratory Service, popularly referred to as “Colindale”, and reviews the types of infection which are commonly food or waterborne and their relative importance. Cholera, typhoid and paratyphoid are rare diseases usually acquired abroad. Bovine tuberculosis, brucellosis and foodborne helmenthiasis have been almost eliminated as indigenous diseases. However, salmonellosis and Campylobacter enteritis are increasing. The increase has not been satisfactorily explained but is probably due to bovine and poultry infections. Although most notified food poisoning incidents are due to salmonella, a number of other organisms have been implicated, the cause being defective food hygiene. Viral foodborne diseases, including hepatitis A, have been associated mainly with shellfish. The incidence of new foodborne infections may be increasing.

A small clinical trial with the Glenn type 3 poliovirus vaccine has shown that the strain is antigenic and retains its attenuated characters on human passage at least as well as any other reported type 3 strain. The antigenicity and stability of the various type 3 vaccine strains should be compared in a larger clinical trial.

The incidence of sepsis due to penicillin-resistant strains of Staphylococcus aureus has increased in recent years, particularly in hospitals and to a less extent in the general population (Elek, 1959). The noses of healthy persons are an important source of pathogenic staphylococci and it has been shown that organisms from the nose may cause sepsis in the same individual (Williams, Jevons, Shooter, Hunter, Girling, Griffiths, and Taylor, 1959). The nasal carrier rate of Staph, aureus in normal adults is between 35 and 50 per cent. (Williams, Blowers, Garrod, and Shooter, 1960). Hospital patients and staff have higher carrier rates than the general population (McFarlan, 1938; Hutchison, Green, and Grimson, 1957), and a large proportion of these carriers harbour penicillin-resistant strains (Barber, Hayhoe, and Whitehead, 1949; Ludlam, 1953; Edmunds, Elias-Jones, Forfar, and Balf, 1955). McDonald, Miller, Jevons, and Williams (1960) estimated the nasal carrier rate of penicillin-resistant strains of Staph, aureus in the general population from a study of Royal Air Force recruits aged 18 to 24 years. However, a further study in the R.A.F. (Miller, McDonald, Jevons, and Williams, 1962) showed that the carrier rate varied with age. The purpose of the present investigation was to find the carrier rates of penicillin-resistant staphylococci at all ages in the general population.

A 54-year-old Jamaican employed as a grinding machine operator developed pulmonary anthrax and died within two days. In the eight days before his illness he had been grinding sterilized bone charcoal delivered in second-hand sacks, some of which had been used to import the raw bone before its sterilization. Bacillus anthracis was isolated from four out of six sacks examined and is considered to have been the source of the infection.

A study of 289 children aged 12-14 years found to be Heaf test positive at routine testing was made to determine the likely cause of the positive tests. Only 12% of children grade 1 Heaf positive were likely to have had a previous infection with Mycobacterium tuberculosis, 49% were likely to have had infections with atypical mycobacteria, and in 39% no cause for the positive Heaf test was found.The positive Heaf test seems to us to be too sensitive. Both a negative and grade 1 positive should be regarded as not significant and these children given B.C.G. vaccine. Heaf grades 2, 3, and 4 should be regarded as significant and the children investigated for M. tuberculosis infection.

The identification of a case of respiratory tuberculosis in a swimming-baths attendant whose sputum was smear positive was followed by intensive contact tracing of children aged 8-11 years who had visited the baths. An outbreak was discovered that otherwise might not have been detected. Out of 3764 children, 108 (2.9%) had evidence of infection: there were 16 cases of tuberculosis, of which 11 were symptomless but showed lesions on chest radiography, and a further 92 with tine test grade 3 or 4 without clinical or radiological signs. The contact of these children with the index case was apparently minimal. Early detection, isolation, and treatment of infectious cases of respiratory tuberculosis and vigorous contact tracing should be given more priority in tuberculosis control.

Many of the traditional infectious diseases have declined or even disappeared and others have shown a change in their epidemio logy in England and Wales over the past 20 years. Diphtheria, poliomyelitis, and smallpox have almost disappeared, while brucellosis, dysentery, hepatitis, measles, staphylococcal in fections, tetanus, and tuberculosis have declined. There have been other changes in the epidemiology of some of these diseases. Staphylococcal infections in hospitals have decreased

An investigation of Salm. saint-paul infection in England and Wales in 1959 is described. In one-third of the human incidents the infection was attributed to home-produced meat coming from two infected abattoirs.Animal infection was demonstrated and was probably due to contaminated imported animal feedingstuffs.The clinical histories of 55 of the 89 cases reported during the year were studied. There was one death. In ten patients the illness commenced with fever and malaise and diarrhoea was absent or did not occur until 24–48 hr. later. One patient developed meningitis and another an abdominal abscess.

The simultaneous administration of B.C.G. vaccine, diphtheria-tetanus toxoid aluminium hydroxide adsorbed vaccine, and oral poliovaccine was studied in 628 children aged 13-14 years between 1966 and 1969 in Newham, London. The efficacy of these vaccines was unaffected by administering them at the same time; routine simultaneous administration is considered justified when organizational difficulties prevent the attainment of high immunization rates with the vaccines given separately. No adverse reactions to B.C.G. or oral poliomyelitis vaccines took place, but 8% of children had moderately severe local reactions after diphtheria-tetanus aluminium hydroxide adsorbed vaccine, which were attributed to diphtheria toxoid. Serological studies showed the need for immunization against diphtheria, tetanus, and poliomyelitis at 13-14 years of age. Because of the adverse reactions to diphtheria toxoid, however, simultaneous administration of tetanus toxoid aluminium hydroxide adsorbed, oral poliomyelitis, and B.C.G. vaccines only is recommended at present. An “adult type” diphtheria-tetanus toxoid might overcome the problem of reactions, though in two to three years9 time most children aged 13-14 years will have received diphtheria-tetanus-pertussis vaccine in infancy and reinforcement might then be accomplished by a small intradermal dose of the currently available fluid diphtheria-tetanus vaccine. Continued serological studies of diphtheria and tetanus antitoxins and polio antibody are necessary to determine the future need for reinforcement of immunity; such studies should become an essential part of the surveillance of the community immunization programme.

In view of certain difficulties involved in the administration of poliomyelitis vaccine in liquid form on sugar or in syrup in mass campaigns, trials have been conducted with a new single-dose preparation of live attenuated poliovaccine (Sabin strain) in an emulsion in a gelatin capsule. Each capsule contained a standard dose of vaccine which was shown to be stable in this form. It has been demonstrated that the capsule vaccine was as effective as liquid vaccine both in children and in adults. The capsules were acceptable to adults and children over the age of 5 years, but between 6% and 7% of 4-5-year-old children refused the vaccine in this form owing to difficulty in swallowing the capsules.The authors consider that the capsule may be recommended for the routine immunization of older children and adults and for mass vaccination campaigns. It is suggested that the vaccine could be administered to young children and babies in the course of such campaigns by opening the capsule and mixing the contents with water or sweetened liquid in a spoon.

A milk-borne outbreak of Salm. heidelberg infection due to unpasteurized milk from tuberculin-tested cows is described. There were 77 cases and 46 symptomless excreters of the organism. There were no deaths. The infection was traced to a cow with a symptomless salmonella mastitis and the origin of the organism was thought to be contaminated animal feeding stuffs.We are indebted to Dr Joan Taylor, Colindale, for the identification of the salmonella serotypes; to Dr H. R. Cayton, Bristol, for assistance in the examination of animal feeding stuffs; to Dr E. N. Davey, Gloucester, for permission to include his results of milk examinations; and to the following public health inspectors who assisted in the field investigation—Mr A. Furniss, Mr G. Baillie and Mr M. V. Smith, Cirencester Urban District; Mr H. Wheeler and Mr R. Hayward, Cirencester Rural District; Mr P. Hayter, Bristol; and Mr D. S. Smith, Trowbridge.

When, in 1956, inactivated poliomyelitis (Salk) vaccine became available for routine immunization in England and Wales the Ministry of Health set up a scheme of poliomyelitis surveillance. The objects were to provide a means of rapid detection pf pos sible outbreaks of vaccine-induced poliomyelitis, such as occurred in the United States owing to the presence of incompletely inactivated virus in a batch of vaccine (Nathanson and Langmuir, 1963), and to observe the efficacy of the vaccine. The results were reported by Geffen and Spicer (1960), Geffen (1960), and Roden (1964), and though a number of vaccine associated cases occurred they concluded that the vaccine was both safe and effective.

In a survey of enterovirus and adenovirus excretion in normal children in 1961–62, 25,600 faecal specimens were examined, 25,589 of them in cell culture and 17,596 in newborn mice.Polioviruses were isolated from 156 (0·86%) specimens before Sabin vaccination was introduced in February 1962 and from 389 (5·27%) specimens after this. Coxsackie A viruses were isolated from 894 (5·08%) specimens, Coxsackie B viruses from 196 (0·77%), echoviruses from 278 (1·09%) and adenoviruses from 128 (0·50%).The isolation rates of these viruses varied with sex, age, geographical area, type of local authority area and season.The isolation rate of polioviruses before the introduction of Sabin vaccination was the same as in a previous survey carried out in 1957–58, although the rate was lower in Salk vaccinated children than in unvaccinated children. After Sabin vaccination began the isolation rate increased and Type 3 virus replaced Type 1 virus as the most prevalent virus type.