Some of the factors influencing the isolation rate of Bordetella pertussis during a whooping cough epidemic in West Glamorgan, Wales, are reported. The organism was isolated from 39% of patients with clinical whooping cough, pernasal swabbing being much more successful than cough plates. Isolation rates were increased in the non-immunized, particularly in the first year of life. Erythromycin and co-trimoxazole significantly reduced the isolation rate of B. pertussis but this did not occur with penicillin. In this study 20 % of patients were culture positive 6 weeks after the onset of their infection. It is suggested that the Department of Health and Social Security recommendation of a minimum period of three weeks exclusion of children from school is inadequate. During the epidemic, the proportion of strains of B. pertussis containing antigen 2 more than doubled.

Particular epidemiological features of Mycobacterium bovis infection in cattle herds in Great Britain during the period 1972–8 were examined. During these seven years 1099 herds became infected, the mean annual incidence of herd infection being of the order of one infected herd per 1000 cattle herds.

Infection in herds was predominantly a sporadic occurrence; 938 (85·4%) herds experienced only one incident of infection which persisted for less than 12 months. The concentration of infected herds in localized areas of the south-west region England, where infected badgers were the most significant attributed source infection, is demonstrated.

The risk of herd infection in relation to badger sett density was also examined in Cornwall, Gloucestershire/Avon and counties in England and Wales outside south-west region of England. The numbers of herds at risk in six categories badger sett density in these three areas were estimated from three random samples of herds drawn from the annual agricultural census. In Cornwall and Gloucestershire/Avon herd infection, associated with infected badgers or for which no source of infection could be found, was positively associated with badger sett density. A similar association between herd infection, not attributable to a source of infection, and badger sett density was found in counties in England and Wales outside the south-west region of England.

Newborn calves were bled at monthly intervals and examined for serum antibodies to bluetongue virus (BTV). Maternal immunity persisted for 3 months and it was possible to calculate decay rates for virus neutralizing antibody. Calves were subclinically infected with BTV within a few months of becoming susceptible and neutralization tests were used to deduce the serotype responsible. A profile of virus activity was built up over a 12 month period. Frequent light trap catches were used to examine the population dynamics of suspected Culicoides vector species. Two species, imicola and schultzei were present throughout the wet and dry seasons and survival rates were sufficiently long to account for virus transmission at any time of the year.

One hundred and thirty-one strains of Escherichia coli isolated from the cerebrospinal fluid of patients in the United Kingdom were tested for resistance to 13 antimicrobial drugs. Sixty-four strains (49%) were resistant to one or more drugs and 44 (34%) were resistant to three or more drugs. Resistance to ampicillin, sulphonamides, streptomycin and tetracycline occurred most frequently.

Well water was sampled from all four major wards in Katsina town. All 20 samples taken showed high coliform counts. Sixty-five per cent contained ≥ 2400 coliforms per 100 ml while the remainder had counts ranging from 79 to 920. Faecal coliforms and non-cholera vibrios were detected in all samples. There was no significant relationship between the coliform counts and the distances of latrines to wells, water table to ground level, slope relationship between wells and latrines, the pH of water and whether the wells were left permanently open or not. Salmonella sp., Enterobacter sp. and Pseudomonas sp. were each isolated from about 10% of the samples, while Proteus sp. was isolated from 40%, Citrobacter sp. 15%, Alcaligenes sp. 5% and an unidentified Gram-negative rod from 5%.

Only 2 (10%) of the sampled households, representing 23 (9·6%) of the 239 people exposed to well-water had pipeborne water in addition. It was concluded that well water in Katsina town could be a human health hazard.

Sera from 96 patients with Mycoplasma pneumoniae infection were examined for specific IgM antibody. The complement fixation test was used to measure the IgM after separation by ultracentrifugation through sucrose density gradients. Of patients under the age of 20 years 78 % displayed positive specific IgM titres. In older patients only 34% were IgM positive. The specific IgM remained detectable, but at decreasing levels, during the follow-up period of 5 months. This diagnostic technique appears to be of value in children and young adults experiencing primary infection with M. pneumoniae.

A five-tube most probable number (MPN) method, with pre-enrichment and enrichment stages, was used in a study of the incidence of salmonella contamination of British fresh sausages and the ingredients used in their manufacture. All samples were taken from a large factory in the course of routine production. There was an incidence of 65 % contamination of pork (n = 20) and 55% (n = 20) in pork and beef sausages. The incidences of contamination of uncooked ingredients varied from 95 % for mechanically recovered meat (n = 20) to 10 % for another type of meat. Cooked and/or dried ingredients were rarely contaminated with these organisms and, when contamination occurred, coliforms were also important.

The numbers of salmonellas isolated ranged from 7–40 for pork sausages, from 8–24 for beef and pork sausages and from 0·8–378 organisms/g for ingredients.

The following salmonella serotypes were isolated (ranked in descending order of incidence): S. derby, S. dublin, S. newport, S. stanley, S. typhimurium, S. heidelberg, S. infantis and S. agona.

Outbreaks of abortion associated with infection by Salmonella montevideo have affected sheep in the east, especially the south-east, of Scotland each year since 1972. Disease in the north and north-east was usually less severe.

Between 1 January 1970 and 31 December 1981, a total of 67 incidents affecting sheep were reported by veterinary laboratories to the Communicable Diseases (Scotland) Unit, 87 % of which presented during the main lambing months of February, March and April. Twenty-one episodes of bovine infection were also recorded over the same period, 17 of which involved single animals only, usually an aborted cow or a scouring calf.

Despite intensive investigations, neither the origin nor the mode of spread of S. montevideo infection among sheep and cattle in Scotland has been established with any certainty, although there has been considerable evidence indicating the role of scavenging wild birds, particularly seagulls, as vectors transmitting infection to other farms in the same district. Also largely unexplained are the differences in the epidemiology and clinical pattern of disease in the south-east compared to the north and north-east, while sheep in the west of Scotland have remained virtually unaffected throughout.

The names Citrobacter koseri and C. diversus are synonyms for a species of enterobacterium with a particular ability to cause neonatal meningitis. 517 strains belonging to this species were examined using biotyping and serotyping techniques. 40 % of the strains belonged to serogroups O2 and O1 and 72 % belonged to biotypes d and a. Strains isolated from cerebrospinal fluid belonged to several different serogroups and biotypes but serogroups O2 and O3 and biotypes d and e were the most common. All the strains were resistant to ampicillin, 42 % were resistant to neomycin/kanamycin and 38 % were resistant to cephaloridine. 37 % of the strains were resistant to three or more drugs.

In a collaborative study 12 Public Health Laboratory Service laboratories and the Division of Hospital Infection, Central Public Health Laboratory, investigated the degree of contamination of standard dressings produced by manufacturers in India or in England by a comparison of the results of culture of 25 sterilized dressings with those of 25 untreated dressings. Of the 38 batches of dressings made in India 27 (71 %) were judged contaminated and another six could be so judged when Bacillus species were examined. In two batches laboratory contamination precluded a judgement and only three batches passed the test. Of the 27 batches made in England, only three gave any evidence of contamination at the lowest level of significance. Repeat investigation of one of these batches gave no evience of contamination.

Organisms of the genus Bacillus and fungi were associated with contamination; micrococci and propionibacteria were laboratory contaminants. There was evidence for both failure of sterilization and of contamination after sterilization during the manufacture of dressings.

Concentrations of the rodenticide ergocalciferol (vitamin D2) in samples of rodent baits laid in foodstores and in the laboratory were monitored over several months. Bait samples were solvent extracted and ergocalciferol concentration determined by high pressure liquid chromatography (HPLC). Ergocalciferol levels were constant for more than 21 days in dry samples and did not fall by more than 30% in 100 days. When water (10% w/w) was added to the baits in the laboratory the ergocalciferol concentration fell by approximately 30 % in 30 days. In these wet laboratory samples there was a rapid visible growth of fungus and in normal rodent control use baits should have been replaced when such deterioration became evident.

This paper uses relatively simple and deterministic mathematical models to examine the impact that different immunization policies have on the age-specific incidence of rubella and measles. Following earlier work by Knox (1980) and others, we show that immunization programmes can, under some circumstances, increase the total number of cases among older age groups; the implications for the overall incidence of measles encephalitis and of congenital rubella syndrome are examined, paying attention both to the eventual equilibrium and to the short-term effect in the first few decades after immunization is initiated. Throughout, we use data (from the U.K., and U.S.A. and other countries) both in the estimation of the epidemiological parameters in our models, and in comparison between theoretical predictions and observed facts. The conclusions defy brief summary and are set out at the end of the paper.