The suitability of serological surveys of roe deer (Capreolus capreolus) in determining the spread of tick-borne encephalitis virus (TBEV) was tested in a south German area with a low risk of TBEV infection to humans. Sera obtained from 192 hunted roe were screened by an haemagglutination–inhibition test (HAI) and in an ELISA developed in our laboratory. Those found positive were tested in a neutralization test (NT). Fifty (26·0%) sera reacted positive by ELISA and 43 (86·0%) of these were confirmed by HAI or NT. Forty-seven (24·5%) samples were positive by HAI, 44 (93·6%) of which were also positive in NT or ELISA. Only insignificant increase of the antibody prevalence with age (P = 0·17 for HAI antibodies) suggests that most infections occur at an early age in scattered natural foci. The antibody prevalence in females was lower than in males (OR = 0·63; P = 0·02 for HAI antibodies). In determining the distribution of seropositive roe we increased the sample size to 235 sera. No antibodies were detected in 56 (23·8%) sera collected in the eastern third of the county. The areas of high antibody prevalence in roe match those in which humans have been infected. We conclude that serosurveys of roe deer are useful in marking out areas in which humans face the risk of infection, provided that an adequate number of sera, preferably from males, is available.

Between April and September 1993, a nationwide outbreak of salmonellosis occurred in Germany which was traced to contaminated paprika and paprika-powdered potato chips. Of the estimated 1000 cases, children below 14 years were principally affected. Levels of 0·04–0·45 organisms per gram were found in the snacks. The infective dose was estimated at 4–45 organisms with an attack rate of 1 in 10000 exposed persons. The unique feature of the outbreak was the variety of serovars involved. S. saintpaul, S. rubislaw and S. javiana were isolated during the same time period from paprika powder, spice mixtures, snacks and patients. Their clonal identity was confirmed by molecular typing methods. Furthermore, monophasic and non-motile strains of rare salmonella O-groups were isolated from both paprika products and patients. This is the largest documented outbreak due to contaminated spices which proved that even extremely low numbers of salmonellae adapted to the dry state were able to cause illness.

Serological surveillance of measles immunity has been carried out in England since 1986/7. Results from sera collected in 1989–91 revealed that the proportion of school age children who were susceptible to measles was increasing, following the introduction of the measles, mumps and rubella vaccination programme in October 1988. Mathematical models are used to interpret these data and determine whether this increasing susceptibility is sufficient to allow a resurgence of disease from the low levels achieved by 1993. The models summarize serological profiles by a single parameter, the reproduction number R, which quantifies the level of herd immunity in the population. Results showed that there was cause for concern over the levels of susceptibility to measles, with an epidemic of over 100000 cases likely in 1995/6. These predictions are consistent with trends in the incidence and age distribution of measles and have enabled the planning of a major vaccination campaign.

Methods of transmission of Jembrana disease, an acute and severe disease of Bali cattle (Bos javanicus) caused by a recently-identified bovine lentivirus known as Jembrana disease virus, are described. During the acute disease virus can be detected in saliva and milk. There is evidence of direct transmission from acutely affected animals in close contact with susceptible cattle, possibly by virus in these secretions infecting cattle by the conjunctiva!, intranasal or oral routes, by which it was possible to infect cattle experimentally. During the acute disease the titre of infectious virus in blood is high, about 108 50% cattle infectious units (ID50)/ml, and it is probable that the virus is also transmitted mechanically by haematophagous arthropods. Recovered cattle are also a potential but probably infrequent source of infection; recovered cattle are persistently viraemic but the titre of infectious virus in blood decreases to about 101 ID50/ml by 60 days after recovery from the acute disease, and virus cannot be detected in secretions.

An outbreak of Salmonella enteritidis PT 6B food poisoning, the first reported of this recently described phage type, resulted in illness among 46 of 49 members of a camping group in North Wales. 33 of whom were hospitalized. Epidemiological evidence (P < 0·0001) indicated that a lemon meringue pie was the vehicle of infection. Fresh shell eggs, stored after purchase at ambient temperature, appear to be the most likely source of infection, with multiplication during preparation and subsequent storage of the pie a significant contributory factor. Campers may be at greater risk than others and should consider the use of cold boxes for the transport and storage of eggs, and avoid the preparation of lightly cooked egg products under these basic conditions.

Over 8000 ready to eat foods were examined for the presence of Listeria species. Overall. 5% of foods were found to contain these organisms. Higher occurrence was found in some foods such as chicken (11%) and fish (14%). Most of the Listeria species isolated were L. monocytogenes (49%) and L. innocua (36%) with lower numbers of other species. No seasonal pattern in the recovery of L. monocytogenes was found. Unsatisfactory or potentially hazardous levels of L. monocytogenes were found in 14 products (< 0·2%). mostly cooked meats. Undercooked chicken products appeared to present the greatest risk for the duration of this survey. The small number of samples which were potentially hazardous suggests that the risk to consumers is not high, and this is confirmed by the absence of clinical cases in the region during the period of study.

The prevalence of antibody to hepatitis A virus (HAV) in a group of socially and economically disadvantaged Spanish gypsy children was compared to that of a group of non-gypsy middle-class children. The study included 438 children, 73 gypsies (38 girls and 35 boys, mean age 8·5 years, age range 2–16 years) and 365 non-gypsy controls, randomly selected by age. The presence of anti-HAV was investigated using ELISA.

Among the gypsy children, 82% had antibodies to HAV compared with 9·3% of the children in the control group. The unfavourable living conditions of the gypsy population (e.g. homes with poor sanitary conditions, overcrowding) may explain the high prevalence of HAV infection. These findings underline the need for specific action which targets disadvantaged populations.

Gastro-intestinal diseases continue to be a major health problem in primary schools in the UK. This study, which took place in 20 primary schools in the Leeds area, investigated the presence of faecal indicator bacteria on children's hands and environmental surfaces. Faecal streptococci were used as an indicator of faecal contamination.

A handwashing knowledge score was developed for each child. Those children with good hygiene knowledge had less faecal contamination on their hands (relative risk: 1·4. 95% CI = 1·09–1·81, P = 0·005). Those schools with higher hand counts were more likely to have had a reported outbreak of gastroenteritis in the past. Values of the Townsend Deprivation Index, an indicator of deprivation, were compared with the hand results and those schools in high deprivation areas had higher hand counts. Of the swabs taken from surfaces in the toilet areas and classrooms, the carpets in the classrooms were the most frequently contaminated surfaces.

Over Christmas 1993, an outbreak of food poisoning occurred among guests in a hotel in South West Scotland. Evidence from a cohort study strongly suggested that raw oysters were the vehicle for infection, probably due to a Small Round Structured Virus (SRSV). Detailed enquiry about the source and preparation of the oysters revealed no evidence of any unsafe handling at any stage in the food chain, nor any evidence of bacterial contamination. It is suggested that the present standards of preparation and monitoring are inadequate to protect the consumer, and that bacteriophage monitoring may be a useful method of screening for viral contamination in future.

The prevalence of antibodies against Entamoeba histolytica was studied in the Mexican population using an immunoenzyme assay in solid phase (ELISA) and semiautomatic equipment. The antigen was a mixture of membrane proteins obtained by Triton X-100 extraction from an axenic culture of Entamoeba histolytica HM1-IMSS. The method was standardized by comparing serum samples from amoebic liver abscess patients with healthy volunteers. From the 60538 samples supplied by the National Seroepidemiology Survey, antibodies were found in 4·49 % (4·32–;4·65% at 95 % confidence limit). More significant titres occurred in the central region of the country. The ratio female to male was 1·25:1. The population living in metropolitan areas had probably been infected at a younger age than those living in the country.

Important differences were found in the seroprevalence obtained by ELISA compared with a study which used indirect haemagglutination (IHA) in the same sample frame.

The role of hand-genital transmission in the aetiology of genital warts is unclear. However this route is suggested by a number of observations including the relatively high proportion of genital warts in children which contain HPV types 1–4 (15% for children and 2% for adults). We compared two transmission models; one which assumes that hand-genital transmission occurs and one that it does not, and determined the conditions in which each model can reflect the available prevalence data. Hand-genital transmission provides a simple explanation of the observed differences in the proportions of genital warts containing HPV types 1–4 and 6/11 in children and adults. If hand-genital transmission does not occur, the observed difference could only be explained by an eightfold greater probability of transmission to children of types 1–4 than types 6/11, or by an eightfold greater duration of infection with types 1–4. Our findings provide support for the view that genital warts may be transmitted by hand-genital contact.

An outbreak of cyptosporidiosis occurred in late April 1993 among resort hotel guests which was temporally associated with, but geographically distant from, a massive waterborne outbreak of cryptosporidiosis in Milwaukee, Wisconsin, that occurred in late March and early April of 1993. A case-control study was performed among groups with members who reported illness and among a systematic sample of groups who stayed at the resort hotel during the risk period. Of 120 persons interviewed, 51 (43%) met the case definition. Swimming in the resort hotel's pool was significantly associated with case status (OR = 9·8; 95% Cl 3·4, 29·7), as was consumption of ice from the hotel's ice machines (OR = 2·3; 95% Cl 1·01, 5·2). When analysis was restricted only to laboratory-confirmed cases and controls, swimming pool use was the only risk factor significantly associated with illness (OR=13·0; 95%C1 2·6, 88·7). Following waterborne outbreaks of cryptosporidiosis associated with water supplies, swimming pools should be considered as possible ongoing sources for transmission regionally.

A 3-year study of spotted fever group rickettsial ecology in Inner Mongolia revealed that nearly half of the human population tested had antibodies to Rickettsia sibirica detected by complement fixation test. Infected persons, ticks and a high proportion of seropositive livestock and wild rodents were found in all five vegetation zones (desert, steppe, forest, forest-grassland and grassland).

In an outbreak of cryptosporidiosis in Warrington. a town in North-West England. 47 cases were recorded between November 1992 and February 1993. most within the first month. There was a strong statistical association between cases and residence in an area supplied from two groundwater sources. In a case-control study, a strong association between having drunk unboiled tap water from these sources, and a dose-response relationship were found. Oocysts were not detected in the water supply. During very heavy rainfall one source of water was found to drain surface water directly from a field containing livestock faeces, thereby bypassing natural sandstone filtration. Exceptionally heavy rainfall occurred at the probable time of infection. After withdrawal of the original water supply, the outbreak rapidly subsided. It was concluded that there was very strong evidence that this outbreak was waterborne. This, the second documented outbreak of cryptosporidiosis attributable to a groundwater supply, demonstrates that infection can be transmitted from a disinfected groundwater source despite apparently satisfactory treated water quality. We recommend that guidelines for protection of groundwater are implemented, raw groundwater should be routinely monitored for microbiological contamination, and the structure of all sources and waterworks should be assessed in risk surveys of water catchment areas.

The reservoir host of cowpox virus in Western Europe is not known, but epidemiological evidence from human and feline infections indicates that the virus is probably endemic in small wild rodents. Therefore, serum and tissue samples were collected from a variety of wild British mammals and some birds, and tested for evidence of Orthopoxvirus infection. Antibody reacting with cowpox virus was detected in 9/44 (20%) bank voles (Clethrionomys glareolus), 8/24 (33%) field voles (Microtus agrestis), 17/86 (20%) wood mice (Apodemus sylvaticus) and 1/44 house mice (Mus musculus), but in no other animal species tested. Although virus was not isolated from any animal, this serological survey, together with other evidence, suggests that bank and field voles and wood mice are the main reservoir hosts of cowpox virus in Great Britain.

This paper compares strains of foot-and-mouth disease (FMD) serotype SAT (South African Territories) 2 viruses isolated from Zimbabwe and other African countries using monoclonal antibodies (MAb). A sandwich-ELISA was used to examine the relative binding of anti-SAT 2 MAb to the various viruses. The MAb-binding profiles of viruses isolated from field samples were compared using hierarchical cluster analysis. Viruses were obtained from game animals, mainly African buffalo (Syncerus caffer) which is the natural host and reservoir for SAT serotypes in Africa, and from cattle showing clinical signs of FMD, as well as from animals suspected of carrying the virus subclinically. Some isolates have been adapted for use as vaccine strains. The results showed that most of the Zimbabwe isolates collected between 1989 and 1992 were an antigenically closely-related group. Although differences were observed between Zimbabwe isolates collected between 1989 and 1992 and those collected in 1987, there was no correlation with the different MAb binding patterns within the 1987 group and the epidemiological information received from the field. Similar profiles were observed for many SAT 2 viruses, including viruses isolated over a 50-year period and from geographically distant areas. This indicates an inherent stability in antigenic profiles of SAT 2 viruses. The MAb panel was capable of assessing antigenic variation, since very different profiles were obtained for some isolates. The work also allowed comparison and characterization of anti-type SAT 2 MAb from different laboratories. The findings are discussed with reference to selection of vaccine strains.