An outbreak of gastroenteritis in the infant–toddler unit of a child care centre (CCC) in Pretoria, South Africa, was investigated for possible viral enteropathogens. Rotavirus was found in association with seven (70%) diarrhoeal episodes. Co-infection with rotavirus and human astrovirus (HAstV) was demonstrated in two of these episodes, and rotavirus, HAstV and enteric adenovirus (EAd) co-infection in another. Rotavirus occurred alone in four of the diarrhoeal episodes, while HAstV and EAd were each detected alone in one episode. Two HAstV and one rotavirus asymptomatic infection episodes also occurred. Overall, 8 of 10 children had rotavirus infections, of which 7 were symptomatic, 6 of 10 children had HAstV infections (4 symptomatic), and 2 of 10 children had EAd infection, both symptomatic. These results highlight the diversity of viral enteropathogens that may be associated with a diarrhoeal outbreak in a CCC and emphasize the need to investigate the possibility that multiple enteropathogens may simultaneously cause a single outbreak of diarrhoea.

Partial nucleotide sequence of the capsid polypeptide coding gene 1D (VP1) was determined for 68 serotype O foot-and-mouth disease viruses isolated between 1983 and 1995 from outbreaks occurring in Saudi Arabia. The sequences were compared with previously published sequences: 14 viruses of Middle Eastern origin (isolated between 1987 and 1991); and with four vaccine virus strain sequences, three originating from the Middle East (O1/Turkey/Manisa/69, O1/Sharquia/Egypt/72 and O1/Israel/2/85) and one from Europe (O1/BFS 1860/UK/67). The virus isolates from Saudi Arabia and the Middle East vaccine virus strains formed a related genetic group distinct from the European O1virus. Within this large group 12 distinct genetic sublineages were observed.

Enterotoxigenic Escherichia coli (ETEC) adhere to the intestinal mucosa by a number of fimbrial colonization factors (CFs) that have been claimed to induce only type-specific immunity. However, adult Bangladeshi patients infected with CFA/I-expressing bacteria, developed significant plasma IgA antibody responses, as determined by enzyme-linked immunosorbent assay, not only against the homologous fimbriae but also against several heterologous CFs, i.e. CS1, CS2, CS4 and PCFO166 fimbriae. In contrast, North American volunteers, who had probably not been infected by ETEC previously, responded with serum IgA against CFA/I fimbriae but not against any other CFs after symptomatic infection with CFA/I-expressing ETEC. Thus, infection with CFA/I-expressing bacteria may boost immune responses against CFs with a related amino acid sequence in previously primed subjects.

In 1996 Japan had a big outbreak of enterohaemorrhagic Escherichia coli (EHEC) O157[ratio ]H7, especially in Osaka prefecture where about 6000 patients (mainly schoolchildren) suffered from diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome (HUS) due to EHEC infection via school lunch. Our survey of doctors who took care of those patients showed that most patients had received antibiotics, especially fosfomycin which comprised 84% of the prescribed treatment. Since the administration of antibiotics for EHEC infection is under discussion, we analysed the effect of fosfomycin on production/release of verotoxins (VTs). Addition of fosfomycin into EHEC culture in CAYE broth at 2 and 5 h after start of incubation caused marked increase of VT1 release. This observation warns of the possibility of fosfomycin treatment making the disease worse.

A population-based case-control study to determine social and behavioural risk factors for Taenia solium cysticercosis in humans was carried out in a rural area, Shandong province, China. Forty-eight cases with cysticercosis were ascertained through a prevalence survey conducted among 7281 persons in 1993. For each case, four controls residing in the same village and matched for age and sex were randomly selected. Information regarding demographic, social and behavioural factors was collected during house visits through interviews and direct observation. Risk factors strongly associated with human cysticercosis included poor personal hygiene, being unable to recognize cysticerci-containing meat, poor pig-raising practices and a history of passing tapeworm proglottides. The results indicate that health education in combination with chemotherapy for taeniasis is required for the control of cysticercosis in humans.

We compared the prevalence of salmonella in faecal samples from finishing pigs and in feed samples from swine herds in North Carolina, USA. Farms were either finishing sites using all-in/all-out management of buildings in multiple-site systems (14 farms) or farrow-to-finish systems using continuous flow management of finishing barns (15 farms). The two groups of herds differed with respect to several management variables. Salmonella were isolated from 565 of 2288 (24·6%) faecal samples and from at least 1 faecal sample on 24 of 29 (83%) farms. Predominant serotypes were S. derby, S. typhimurium (including copenhagen), S. heidelberg, S. worthington and S. mbandaka. Fewer farrow-to-finish farms were detected as positive compared with all-in/all-out farms. Prevalence was lower for pigs raised on slotted floors compared with all other floor types, and was highest for pigs raised on dirt lots. Modern methods of raising pigs in multiple-site production systems, using all-in/all-out management of finishing pigs, appear to have no benefit in reducing the prevalence of salmonella compared with conventional farrow-to-finish systems.

Cryptosporidium parvum infections of domestic animals can have a considerable economic impact and as oocysts are voided in the faeces of infected hosts, environmental contamination with agricultural waste has also become a matter of concern. Since only viable oocysts are potentially infectious, the numbers of oocysts excreted during infection can have important implications for both veterinary and public health. During the course of infection in experimentally infected lambs, oocyst viability was assessed by a fluorogenic vital dyes assay and by a maximized in vitro excystation assay. The excreted oocyst populations contained a higher proportion of viable oocysts 5–11 days post infection (d.p.i.) than later in the infection. Oocyst viability declined consistently 11–15 d.p.i. and coincided with periods when peaks in serum and intestinal anti-Cryptosporidium antibodies have been reported to occur. Infected lambs excreted a mean of 4·8 (standard error [S.E.]±0·4)×109 oocysts per g of faeces, of which half were non-viable and therefore of no significance for disease transmission. This study demonstrates that the numbers of viable oocysts excreted by infected lambs is smaller than previously suspected.

Samples of rectal faeces were collected immediately after slaughter from 400 cattle each month for a 1-year period and from 1000 each of sheep, pigs and poultry over the same period. Samples were examined for Escherichia coli O157 by enrichment culture in buffered peptone water with vancomycin, cefixime and cefsulodin followed by immunomagnetic separation and culture of magnetic particles onto cefixime tellurite sorbitol MacConkey agar. E. coli O157 was isolated from 752 (15·7%) of 4800 cattle, 22 (2·2%) of 1000 sheep and from 4 (0·4%) of 1000 pigs, but not from any of 1000 chickens. Of the cattle sampled, 1840 (38·4%) were prime beef animals, 1661 (34·6%) were dairy animals being culled and the status could not be determined for the other 1299 (27%) animals. E. coli O157 was found in 246 (13·4%) of the 1840 beef cattle and 268 (16·1%) of the 1661 dairy cattle. The monthly prevalence of E. coli O157 in cattle was 4·8–36·8% and was at its highest in spring and late summer. Seventeen of the 22 isolates from sheep were also made over the summer period. All E. coli O157 isolates from sheep and 749 (99·6%) of the 752 E. coli O157 isolates from cattle were verocytotoxigenic as determined by Vero cell assay and DNA hybridization, eaeA gene positive, contained a 92 kb plasmid and were thus typical of strains causing infections in man. In contrast isolates from pigs were non-toxigenic, eaeA gene negative and did not contain a 92 kb plasmid and would, therefore, be unlikely to be a source of infection for man.

The persistence of Escherichia coli O157[ratio ]H7 in cattle and the farm environment was investigated on eight Ontario dairy farms positive for E. coli O157[ratio ]H7 in a longitudinal study commenced one year previously. Faecal samples from cows, calves, humans, cats, rodents, wild birds, a composite fly sample and numerous composite and individual environmental samples were cultured and tested for verotoxin-producing E. coli (VTEC). VTEC isolates were serotyped and E. coli O157[ratio ]H7 isolates were phage typed. E. coli O157[ratio ]H7 phage type 34 was isolated from one calf on each of two farms. The same phage type had been isolated on one of these farms 12 months earlier. Most E. coli O157[ratio ]H7-positive animals and farms became culture-negative within 2 and 3 months, respectively. E. coli O157[ratio ]H7 was not isolated from any environmental samples, although evidence of VTEC was found in composite samples from calf feeders (19·1%), calf barn surfaces (18%), cow feeders (14·9%), flies (12·5%), cow barn surfaces (11·3%), and individual milk filters (12·5%). VTEC belonging to 21 non-O157 serotypes were isolated from 24 cows (8·2%), 21 calves (18·3%), 2 cow feeder samples (3·0%), and 1 calf feeder sample (4·8%). Shedding of E. coli O157[ratio ]H7 by infected dairy cattle appears to be transient and persistence of E. coli O157[ratio ]H7 was not demonstrated from the farm environment sites tested.

Sixty-three Staphylococcus aureus isolates recovered from bovine sources in the USA and the Republic of Ireland were characterized by multilocus enzyme electrophoresis (MLEE), ribotyping, and random amplified polymorphic DNA polymerase chain reaction (RAPD–PCR) typing at two separate laboratories. The S. aureus isolates were assigned by MLEE to 10 electrophoretic types (ETs) (Index of Discrimination, D=0·779). In contrast, the same isolates were assigned to 13 ribotypes (D=0·888), and to 12 RAPD types (D=0·898). A common clone, ET3, of worldwide distribution, was represented by six distinct combinations of ribotypes and RAPD types. S. aureus clones recovered from cows in Ireland were also associated with mastitis in dairy cows in the USA. These findings are consistent with the hypothesis that only a few specialized clones of S. aureus are responsible for the majority of cases of bovine mastitis, and that these clones have a broad geographic distribution.

Human echinococcosis remains a very serious public health problem worldwide, although a decline in incidence has been observed in some endemic areas during the last decades. However, in some non-endemic areas an increase in new cases and new foci of animal echinococcosis were registered during the same time. In Dalmatia, a well known endemic area of hydatidosis in the most Mediterranean part of Croatia, from the mid-1950s until present a decrease of incidence of over 70% has been registered. Age, sex and occupational category specific incidence as well as lethality rate have remained the same as before. Migrations from rural to urban regions seem to be the most important parameter in the changing epidemiology of human hydatidosis in Dalmatia.

To elucidate the epidemic pattern of a dengue outbreak in southern Taiwan during 1987–8, antibody prevalence rates were investigated in paired sera collected in both epidemic (Kaohsiung) and non-epidemic (Tainan) areas. In Kaohsiung, the IgG prevalence rate in 1989 was significantly higher (9·23%) than that in 1988 (5·29%) suggesting that new infections continuously appeared after the first bleeding in 1988. Although IgG antibody persisted in most infected blood samples, waning of antibody occurred in 6/355 (1·69%) of Kaohsiung sera. IgM antibody was only detected in Kaohsiung sera, suggesting that Tainan was not involved in the outbreak. Because IgG antibody was present in some samples collected in 1989, but not in 1988, from the non-epidemic area, sporadic infections perhaps occurred. Additionally, 4/355 (1·13%) of Kaohsiung sera showed IgM antibody positive in both 1988 and 1989. In turn, secondary infections may have occurred because of circulation of multiple-types of the virus. The possible relationship between low levels of dengue haemorrhagic fever (DHF) and the loss of IgG antibodies over time is also discussed.