In England and Wales human salmonellosis is a major public health problem and, although mortality is low, the disease has important social and economic consequences. All surveillance indicators suggest that an epidemic of unprecedented proportions is occurring. Between 1081 and 1980 the number of strains received for serotyping by the Public Health Laboratory Service (PHLS) Division of Enteric Pathogens has increased by 60% (Table 1). This is predominantly due to strains of Salmonella typhimurium and S. enteritidis. Smaller but significant increases have occurred in the numbers of S. virchow and S. Stanley. With the exception of the latter serotype, which seems to come from a bovine reservoir, the indications aro that poultry is the main source of the increase in infections.

A prospective study of faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of ago was conducted in 751 healthy infants. The influence of breast-feeding and treatment with antibiotics on this colonization was studied. Colonization with P-fimbriatcd E. coli increased with age from 10% at 6 days to 30% at 18 months of ago (P < 0·01). Breast-feeding influenced colonization at 6 weeks of age when breast-fed children harboured fewer bacterial species (P < 0·001) and fewer P-fimbriated E. coli (P = 0·06) than bottle-fed infants. Treatment with antibiotics increased the colonization rate with P-fimbriatcd E. coli at the age of 11 months (P < 0·05). However, this was not true for treatment with ampicillin, which increased colonization rate with Gram-negative species other than E. coli (P < 0·05). Fifty per cent (378) of all children were colonized and a quarter (183) had pure cultures of P-fimbriatcd E. coli in at least one faecal sample. The clinical importance of this colonization remains to be shown.

An investigation was undertaken to determine the isolation rate and antibiotic resistance of Haemophilus influenzae from the nasopharynx of young children. The 996 subjects studied were up to 6 years of age. H. influenzae was isolated from 304 (30·5%) and strains of capsular type b from 11 (1·1%). Age, sibling status, season, respiratory infection and antibiotic therapy all influenced isolation rates. The overall prevalence of antibiotic resistance in the strains isolated was ampicillin 5·4% (all β-lactamase producers), cefaclor 0·3%, chloramphenicol 1·3%, erythromycin 38·2%, tetracycline 1·3%, trimethoprim 5·4% and sulphamethoxazole 0%. Ampicillin resistance was more common in type b than non-capsulated strains.

Tachyzoitcs of the RH strain of Toxoplasma gondii were inoculated intravenously into sheep following which serum samples were collected at approximately weekly intervals for 9 months. The sera were examined by the toxoplasma dye test and two enzymc-linkcd immunosorbent assays (ELISA) specifically developed for investigations of ovine toxoplasmosis. One was an antibody class capture assay for the detection of anti-toxoplasma specific IgM, the other an indirect assay which detected anti-toxoplasma IgG.

Some of the sheep had antibodies to toxoplasma prior to inoculation but none had specific IgM. Sera collected 17 days after inoculation showed that all had raised specific antibody levels but the only sheep that produced specific antitoxoplasma IgM were those that were initially without any antibody. Specific IgM could be detected in all these particular sheep for at least 1 month after infection and up to 3 months in some. Specific IgG persisted at high levels for at least 3 months and could still be detected at moderate levels for at least 9 months. The ELISA methods described are simple to perform and could clearly distinguish between previous infection and this experimental infection with Toxoplasma gondii.

In an experimental study on a piggery it was found that haemolytic Escherichia coli of O-scrotypes 138 or 139 proliferated in the intestinal tracts of pigs following weaning, with E. coli of the 0-138 typo also being occasionally recovered from unwearied pigs, and onco from a sow. Organisms of the O-138 typo produced heat labile enterotoxin and their presence in weaned pigs was associated with the development of severe post-weaning diarrhoea. E. coli of O-130 type produced a vero cell cytotoxin and were associated with a milder diarrhoea in weaned pigs. Under various managemental circumstances the O-138 type E. coli almost invariably proliferated after weaning. The O-139 strain of E. coli did however proliferate rather than the O-138 strain following the movement of weaned pigs to new accommodation, after weaned pigs were returned to their sow and then weaning again 5 days later, and very occasionally in pigs weaned at 5 weeks of ago. In all theso cases earlier proliferation of the O-138 E. coli had been detected, suggesting that this may be a prerequisite for proliferation of the O-130 strain.

A total of 637 strains of Salmonella bareilly received from different parts of India between 1959 and 1985 were phage typed using five locally isolated wild phages. The overall typability was 94·5% and 11 different phagc types could be defined. Phago types 10 and 1 were the most prevalent and the geographical and source distribution is described.

Campylobacter was the bacterial pathogen most prevalent in 850 children, aged 6–59 months, examined in a house-to-house diarrhoea survey in two Liberian communities. 44·9% of the children from an urban slum and 28·4% from a rural area were excretors. Since the prevalence of diarrhoea was very high and consequently many convalescent carriers were found, it was not possible to evaluate the pathogenic role of campylobacter.

The excretor rate increased with ago and was significantly correlated to the uso of supplementary feeding, inversely correlated to the quality of the water supply, and also associated with helminthic infestation. Results from re-examination of 172 children suggested a high intensity of transmission.

The findings all indicate the existence of a heavy environmental contamination with campylobacter, probably of both human and animal faecal origin.

A cross-sectional bacteriological survey of cattle in West Malaysia revealed 14·4% (32/222) had leptospiral infection. Isolates were obtained from all except one herd with prevalence of infection in herds ranging from 0–44·8%. A small number of buffalo urine samples were examined and all of them were found to be negative. A leptospiral isolate obtained from a bovine kidney proved to be n new scrovar of Leplospira interrogans and the name unipertama was assigned to it. Six other leptospiral serovars were isolated, namely canicola, australis, javanica, ballum, pomona and hardjo. All six serovars were isolated for the first time in cattle in Malaysia.

Cattle in Malaysia appear to be the maintenance host for serovar hardjo. The presence of the other serovars in cattle was probably duo to contact with the maintenance hosts, pigs for serovar pomona and rodents for the other three serovars. It appears that the epidemiology of leptospiral infection in cattle in Malaysia is similar to that reported overseas.

Poultry feed was contaminated artificially with either Salmonella kedougou or S. livingstone using a two-stage mixing process. Intestinal infection became established in a small proportion of birds when feed containing between 0·1 and 0·3 salmonellas/g was given continuously for 2 or 3 weeks from the day of their purchase as ‘day-olds’ while nearly all birds became infected when the feed contained 100–300 salmonellas/g. Between these limits a dose response was demonstrated in that the proportion of birds becoming colonized with salmonellas increased as the numbers of salmoncllas added to feed was increased.

Nalidixic acid-resistant strains of both serotypes were used to facilitate the recovery of organisms. The isolation rate was higher from dilutions of euccal contents inoculated directly onto brilliant green agar supplemented with nalidixic acid than it was from swabs of cloacal faeces, even when an enrichment technique was used. This observation confirms that the incidence of salmonella carriage in flocks will be under-estimated if only cloacal faeces are cultured.

Of the two serotypes used S. kedougou proved the more efficient colonizer although for both scrotypes variation in infection rates was demonstrated in different groups of birds given feed containing comparable numbers of salmoncllas.

The distribution of T-and M-protein antigens was determined in 12469 cultures of Streptococcus pyogenes sent to a reference laboratory. Of these 7232 (58%) were isolates from hospital patients, 249 (2%) from hospital staff and 4988 (40%) from the community. The survey extended from January 1980 to June 1987. During this timo the numbers of isolates of M-types 6, 49 and 81 rose then fell, being replaced by types 1, 3 and 28. The proportion of isolates of M-types 4 and 12 remained constant. Few strains were received from cases of nephritis or rheumatic fever but there has been an increase in the number of strains from serious infections and deaths. Forty-four of the 55 (80%) strains received since 1985 from fatal infections have belonged to M-type 1. All other strains, bar two, received from fatal infections in those years belonged to M-type 3. Representatives of M-type 1 were also associated with crysipelas. Types 3 and 4 predominated among the isolates from scarlet fever, types 1, 4, 12 and 49 from nephritis, types 49 and 81 from skin infections in meat workers and type 28 in cases of puerperal sepsis. The M-typability rate was 97% but new M antigens await definition among strains causing pyoderma.

Field studies of human flora carried out in remote environments are often compromised by problems associated with media, equipment or cargo limitations. For the International Biomedical Expedition to Antarctica an anaerobic culture system was developed based on sealed vials, pre-reduccd anaerobically sterilized media, antibiotic selective media and compact processing equipment. The system proved simple to use in a harsh environment and gave results comparable with standard plate and roll-tube techniques. No problems with dehydration, contamination or oxidation were encountered. Furthermore, the system preserved viability of primary isolates for up to 6 months of storage.

During the 1984 cholera epidemic in Mali, 1793 cases and 406 deaths were reported, a death-to-case ratio of 23%. In four affected villages, the mean clinical attack rate was 17·5 and 29% of affected persons died. In 66% of cases the illness began more than 48 h after the village outbreak began, when supplies from outside the village were potentially available. Deaths occurred because patients failed to seek care or received only limited rehydration therapy when they did. Case-control studies identified two routes of transmission: drinking water from one well in a village outside the drought area, and eating left-over millet gruel in a droughtaffected village. Drought-related scarcity of curdled milk may permit millet gruel to be a vehicle for cholera. Cholera mortality in the Sahel could be greatly reduced by rapid intervention in affected villages, wide distribution of effective rehydration materials, and educating the population to seek treatment quickly.

The concentrations of serum IgE (PRIST) and IgE- and IgG-specific antibodies to egg protein were determined in paired sera taken from students who had received influenza virus vaccine. Although persons who gave a history of allergy to egg or to chicken feathers were excluded, 10–16% of vaccinees possessed higher titres of serum IgE and IgE-specific antibody (RAST) to egg white (Fl) allergen before vaccination. The titres of IgG-specific antibody to egg protein (ovalbumin and ovomucoid antigens) were negligible, and did not show any significant response after vaccination. In contrast, IgE-specific antibody to Fl allergen rose significantly in a considerable number of the vaccinccs. The results obtained indicate possible contamination of vaccine products with allergens of egg origin and a potential risk of allergic manifestation after influenza vaccination.

The nucleotide sequences of the haemagglutinin (HA) genes of influenza A (H3N2) isolates from the 1985–6 season in Japan along with those of several viruses isolated between 1982–5 from other countries were analyzed to determine the origin of the 1985–6 Japanese strains. The HA genes of these viruses consisted of 1762 nucleotides and had a three-nucleotide deletion downstream from the stop codon when compared to the sequences of earlier Hong Kong H3N2 viruses. An evolutionary tree of the HA genes of these viruses was drawn using the A/Bangkok/1/79 sequence as the starting point. Eight strains isolated from Asian and Pacific regions including Japan in the 1985–6 season (one in May) had the HA genes located closely on the evolutionary tree but away from those of the isolates in North America and Europe during the 1984–5 season, and a common ancestry for these viruses was suggested.

Rotavirus infection was demonstrated in 168 (29·3%) of 573 children hospitalized for acute diarrhoea in Rome between January 1982 and December 1984. Laboratory diagnosis of these infections was made by transmission electron microscopy and enzyme immunoassay techniques with an overall agreement of 91·3%. Astroviruses, adenoviruses and small round viruses were detected in the faeces of 36 patients (6·4%). Whereas in 1982 rotavirus positive patients were clustered in the winter and following spring, in the following years cases were recorded all year round. The median age of patients with rotavirus infections was 17, 10 and 11·5 months in 1982, 1983 and 1984, respectively. In addition, a smaller number of rotavirus positive cases were admitted in 1983 when compared to those admitted during the previous as well as the subsequent years. It is suggested that a herd immunity was induced in the population by epidemic spread of rotavirus in the first half of 1982.