Five years have passed since Campylobacter jejuni became generally recognized as a common cause of acute diarrhoea (Skirrow, 1977) – although the essential scientific discovery which led to this had been made several years earlier (Butzler et al. 1973) – so this is an appropriate time to take stock of what has happened in that time and consider what we might usefully be doing to control the disease.

It is now seven years since Cossart and her co-workers reported finding a novel parvovirus-like agent (PVLA) infecting man. Although this virus was found as a systemic infection in both Dr Cossart's eleven subjects and a further four subjects described subsequently (Paver & Clarke, 1976; Schneerson, Mortimer & Vandervelde, 1980) it was not until 1981 that a clearly defined clinical syndrome was identified as attributable to infection with this agent. Work in the Departments of Microbiology and Haematology, King's College Hospital Medical School and collaboration with the MRC laboratory at Kingston, Jamaica has shown that infection with the PVLA is the major cause of aplastic crisis in children with sickle cell anaemia (Sergeant et al. 1981, Anderson et al. 1982a, b).

Laboratory studies have provided evidence that the replication of dengue viruses in preparations of primary peripheral blood mononuclear cells of human or simian origin, or in macrophage-like cell lines of human or murine origin, may be enhanced by sub-neutralizing concentrations of homotypic dengue antibody, by heterotypic dengue antibody, or by antibody against heterologous flaviviruses. The mechanism underlying this phenomenon is discussed in the context of dengue haemorrhagic fever and the dengue shock syndrome.

An outbreak of streptococcal pyoderma in a military institution into which fresh susceptible recruits were regularly introduced involved more than 1300 persons over an eighteen-month period. Two M types were responsible for the great majority of the cases and an attack by one conferred immunity to that strain but not to the other. Lesions varied from trivial to disabling. Epidemiological studies indicated that contact – direct or indirect – through such things as gymnasium equipment and room dust was the means of transmission. The outbreak was eventually controlled by vigorous case finding, thorough treatment of cases and the strict application of hygienic principles to prevent spread. There were no late complications and throat streptococci were not involved. It is possible to control such an outbreak without isolation or the making of any significant concessions in the training programme even when large numbers of persons are living and working at close quarters.

A most probable number (MPN) method capable of estimating as few as ten campylobacters per 100 ml of water is described. The method gave results close to those obtained by the viable count method of Miles, Misra & Irwin (1938) with graded suspensions of Campylobacter jejuni. The method was used to test raw water samples: counts were obtained ranging from 10 to 230 campylobacters per 100 ml for 11 of 49 coastal and estuary water samples, and from 10 to 36 campylobacters per 100 ml for 7 of 44 river samples. Campylobacters were isolated from an additional 24 of the ‘negative’ samples by testing 200 ml volumes by glass microfibre filtration and enrichment culture methods. The MPN method should prove to be a useful epidemiological tool particularly suited to the enumeration of campylobacters in particulate fluids.

This paper describes virological and epidemiological features of an infection which killed two of three affected cheetahs at Whipsnade Park in 1977. Two animals had profuse skin lesions and the third had an acute haemorrhagic pneumonia. The outbreak was shown to be caused by cowpox virus. Cowpox virus is believed to circulate in small wild animals, but the source of infection was not traced despite virological and serological tests on 93 captive and 102 wild animals.

Sub-clinical infections did not occur in susceptible contact cheetahs. Immune globulin did not influence the outcome and smallpox vaccine does not take in cheetahs. Management of any future outbreak will rely on prompt diagnosis and segregation of infected animals.

A quantitative culture technique (hand washed in a glove containing broth for 30 s) was used to determine the frequency of hand carriage of aerobic Gram-negative rods by various groups of health care workers and 104 control subjects. Overall, 31 % of health care workers carried aerobic Gram-negative rods on their hands compared to 59% of control subjects (P < 0.001). Enterobacter agglomerans accounted for 40% of the isolates, and other Enterobacter spp. 7%. Other organisms included Acinetobacter calcoaceticus 21 %, Serratia spp. 11%, Klebsiella spp. 10%, Moraxella spp. 3%, Pseudomonas spp. 3%, Proteus spp. 1.5%, Escherichia coli 1%; Morganella morganii, Citrobacter freundii, Aeromonas sp. and an isolate that was not speciated accounted for 0.5% each. We conclude that endemic hand carriage of aerobic Gram-negative rods by health care personnel is common, but significantly less than that of control subjects. Enterobacter agglomerans is found so frequently on the hands of control subjects that it must be considered part of the normal hand flora.

Dog faeces collected from a public park were cultured on selective media for Campylobacter spp. Campylobacter jejuni was isolated from 12 (4·6%) of 260 specimens. In contrast Salmonella spp. were found in only three (1·2%). Six of the 12 isolates were nalidixic acid-resistant thermophilic campylobacters (NARTC), whereas during the same period of study none were found among human isolates. Most of the campylobacter positive faeces were found during June and July. Dog faeces deposited in public places constitute only a small potential source of infection by this organism.

The white pock variant of cowpox virus shows limited growth in chick embryo fibroblasts maintained in arginine-deprived culture medium. Since these conditions inhibit the growth of parental virus, there is a marked increase in the frequency of the white variant in the virus population recovered after passage in the absence of arginine. The variants generated in this system have been characterized by restriction endonuclease analysis of virus DNA in the total DNA recovered from infected cell cultures. Such analysis shows that the white variants arise as deletion mutants of the parental virus, but there was considerable heterogeneity in the restriction patterns of different isolates examined shortly after their generation. Further passage selected white cowpox virus populations with a stable genome configuration comparable with the DNA of pock-purified white variants.

In order to determine whether hand carriage of aerobic Gram-negative rods is continuous we used the glove-handwash technique to sample the hands of two groups (four each) of health care workers with normal hands (surgical intensive care unit, medical ward) and one group (four) with hand dermatitis (HD) and a group (five) of control subjects – secretaries with no exposure to patients. Each subject was sampled repeatedly over three to six weeks. The mean number of samples for each group was 25.2, 23.2, 19.8 and 25.8 respectively. The HD group had more samples positive for aerobic Gram-negative rods than did the other two groups of health care workers while the control group had more samples positive than any of the three health care groups.

Using various typing schemes and the following definition of continuous carriage (the isolation of an organism of the same serotype, pyocin type or biotype from more than two handwash samples) we found that 4 of 11 subjects from whom Klebsiella pseumoniae was isolated carried this organism continuously; 2 of 3 carried Pseudomonas aeruginosa continuously and 4 of 5 of the control subjects carried the same biotype of Enterobacter agglomerans continuously.

We conclude that continuous hand carriage of aerobic Gram-negative rods is common and, among health care workers, those with hand dermatitis carry Gram-negative rods more frequently and in greater numbers than health care workers without hand dermatitis.

A major outbreak of tuberculosis occurred in cattle on a farm in Dorset between 1970 and 1976. Six hundred and twenty-six cattle were slaughtered either because they reacted to the tuberculin test or had been exposed to infection. No source of infection was found until 1974 when badgers infected with Mycobacterium bovis were first discovered.

An analysis of the tuberculin test records of this herd and the six surrounding herds indicated that tuberculosis had been a sporadic problem since the early 1960's. Two peaks of infection occurred in the most severely affected herd in 1970 and 1974 when 29·8% and 27·3% of animals, respectively, reacted to the tuberculin test. These figures are exceptionally high. During the last 20 years there have been two periods when all the herds in the area had synchronous outbreaks consistent with a common source.

Analysis indicated that cattle were at greatest risk in April and May and suggest that there was re-exposure to infection at this time each year. In addition the cattle were apparently exposed to M. bovis, at sufficiently high levels for transmission to occur, for only a relatively short period of time.

Vibrio parahaemolyticus was isolated from 53 out of 584 samples (9·1%) of market fish. All strains were Kanagawa negative and were distributed as follows: sea fish 5 out of 370 samples (1·4%), shellfish 48 out of 214 samples (22·4%). Other fish spoilage microflora recovered were: Alcaligenes faecalis, Pseudomonas aeruginosa, Proteus vulgaris, Aeromonas spp. and Vibrio alginolyticus. Total aerobic counts and coliform counts per gram for the lake fish ranged from 2·6 × 102 to 6·6 × 107 and 10 to 1·0 × 102, respectively. Those from marine fish ranged from 1·0 × 105 to 8·8 × 105 and 2·0 × 103 to 1·6 × 104, respectively. Counts for marine fish gills alone ranged from 1·4 × 105 to 3·4 ×108 and 7·2 × 102 to 1·4 × 107, respectively. No hightemperature (44°) coliforms were recovered from either lake or marine samples.

Following a major outbreak of tuberculosis in cattle on a farm in Dorset, badgers were discovered to be infected with Mycobacterium bovis. Two hundred and forty sets were found in the 1200 hectares of the study area. The sets were found predominantly in areas of Portland Sand. A high prevalence of tuberculosis was found in the badger population which was removed and repopulation prevented for 3 years. The removal of the infected badgers led to the resolution of the problem in cattle. Re-colonization of the area has progressed slowly and the cattle have remained free from infection for a period of 5 years.

White pock variants of cowpox virus give papular lesions on intradermal inoculation of rabbits, without the necrosis and haemorrhage that are produced by wild type cowpox viruses. Rondle & Dumbell (1962) have shown that white pock variants of cowpox virus fail to produce a specific, precipitating antigen which they called ‘d’ substance. In this paper it is shown that ‘d’ is demonstrable in soluble antigen preparations of rabbitpox virus and of neurovirulent strains of vaccinia virus but not in soluble antigens of variola viruses. Two series of recombinant viruses prepared by Dumbell & Bedson (1964) from variola and cowpox and from variola and rabbitpox viruses were tested for the production of ‘d’ substance. These results were compared with the previously recorded effects of these recombinants when inoculated intradermally in rabbits. It is concluded that functional genes determining the production of ‘d’ and of rabbit skin pathogenicity are closely linked on the pox virus genome, but that there is insufficient evidence to say that the two functions are interdependent.

Prisoners and attending staff from six houses of detention were screened for serum HBsAg, antiHBs, antiHBc and transaminases. Both prisoners and warders showed an increased prevalence of HBV serum markers with respect to age- and sex-matched general population control groups. The HBsAg carrier rate was 6·7% in prisoners and 6·6% in staff. Sixty-five per cent of the HBsAg-positive subjects were antiHBe-positive. When the blood samples were taken, all the HBsAg-positive subjects were asymptomatic; transaminases were normal in 80% and only slightly elevated in 20%.

Illicit drug abuse was found to be a relevant risk factor for HBV infection among prisoners under 35 years of age, but not in the older group, whereas no correlation emerged between presence of HBV serum markers and tattoos or admitted homosexuality. A high prevalence of HBV serum markers was also found among young warders who had been in service for a short time: most of them, however, come from areas of Italy with a particularly elevated HBV circulation.

Although the results suggest that many of the HBV infections are not recently acquired within the institution, this survey confirms that prisons should be regarded as high risk areas for HBV infection, both for prisoners and warders.

The international reference strains of variola major (Harvey) and of variola minor (Butler) were grown in cultures of skin and muscle cells from human embryos. The development of infective virus, complement-fixing antigen, haemagglutinin and cytological changes were followed at four temperatures between 35 and 40 °C. No significant difference was found in the amount of virus produced by Harvey or Butler viruses at any of the experimental temperatures, but Harvey attained the plateau titre at 16 h, some 4 h ahead of Butler in the cultures incubated at 38 °C. Harvey also produced a higher and more prolonged yield of virus in the extracellular medium of cultures, inoculated at low multiplicity and incubated at 37 °C. At 38 °C small inocula of Harvey produced foci which developed and spread till the whole culture was necrotic; Butler foci did not spread and remained relatively undeveloped at this temperature.

A large sample of the wild mammals found on a farm in South Dorset were trapped and examined for the presence of Mycobacterium bovis following the discovery of widespread infection in cattle and badgers. M. bovis was isolated from the lymph nodes of two out of 90 rats (Rattus norvegicus) and one out of seven foxes (Vulpes vulpes) but no lesions of tuberculosis were observed. It was concluded that the badger was the only species of wild mammal which was a reservoir of M. bovis in this area.

The bacterial colonization of the large bowel of 11 pre-term, low birth weight neonates who were nourished by expressed breast milk was examined by culturing serial faecal samples and compared to that observed in eight breast-fed and seven formula-fed full-term neonates.

Pre-term neonates were colonized by high counts of facultatively anaerobic bacteria from the first days of life while bifidobacteria colonized only six babies during the first week and appeared in only one baby before day 5. Bacteroides spp. and clostridia were isolated from seven and six pre-term babies respectively during week 1 and were first observed on day 2.

The intestinal colonization of pre-term infants differed from that in full-term breast-fed infants in the high counts of facultatively anaerobic bacteria and late appearance of bifidobacteria, and from both groups of full-term infants in the early stable colonization by Bacteroides spp.

It is postulated that the composition of the normal intestinal microflora of pre-term low birth weight babies contributes to their predisposition to neonatal necrotizing enterocolitis. Results are discussed in relation to the effect of infant feeding regimens on intestinal microbial populations.

The Virus Reference Laboratory, Colindale, first embarked on laboratory investigations for smallpox early in 1947. From then, in conjunction with the Department of Bacteriology, University of Liverpool, it provided a complete diagnostic service throughout England and Wales until 1962, after which the service became available regionally until eradication was effected. Up to 1970 it had investigated 2696 specimens from suspected cases of smallpox and had recovered 108 strains of variola and 248 of vaccinia virus. These last were from persons suffering the complications of vaccination. Some outbreaks following smallpox importation are discussed but infection among laboratory staff during this period was not demonstrated.