This data linkage study examined the extent of hepatitis B transmission and co-infection with HIV among 636 former inmates of Glenochil prison, Scotland, during an outbreak of bloodborne diseases in 1993 which was related to needle sharing. Eleven inmates imprisoned during the first half of 1993 presented with hepatitis B infection, of whom co-infection with HIV was detected in six. Based on dates of test results in relation to time of imprisonment, seven definitely acquired their hepatitis B infection within the prison. Only two infections were reported to Scotland's hepatitis B register and neither could be prison-linked. This outbreak of hepatitis B is the first of its kind to be reported but not the first to have occurred. It not only highlights the urgency for measures to prevent further spread of infection among prisoners but also illustrates the need for comprehensive surveillance of hepatitis B infection, and the need for a protocol on how to manage such outbreaks and on how to establish the extent of transmissions when acute hepatitis B occurs in prison.

In order to determine whether infection with Schistosoma japonicum is related to a higher rate of infection with hepatitis B virus and/or to a higher probability of HBsAg chronic carriage, a population based survey was carried out in China in which HBV markers were studied in 112 subjects with long-lasting S. japonicum infection, and 93 subjects with no S. japonicum infection 37·5% of the cases and 40·9% of controls showed no markers of HBV infection. The prevalence rate of HBsAg was 12·5% in the cases and 12·9% in the controls. For anti-HBc and anti-HBs the figures were 59·8% and 59·8%, and 27·9% and 35·0%, respectively. These data do not support the hypothesis of an interaction between infection with hepatitis B virus and S. japonicum.

The seasonality and factors associated with Cryptosporidium infection were assessed in a cohort of HIV-infected patients in Los Angeles County to better define the epidemiology of cryptosporidiosis among individuals with HIV. Data were analysed from a cohort of 4247 patients [ges ]13 years of age with HIV infection enrolled from four outpatient facilities in Los Angeles, 1990–6. Cryptosporidiosis was diagnosed in 120 (2·8%) patients. Among the 1296 individuals with complete follow-up until death, cryptosporidiosis occurred in 69 (5·3%). The seasonal rate of cryptosporidiosis showed a modest bimodal trend with the highest rates occurring in March–May and September–October. There was no difference in the rate of cryptosporidiosis for the periods of heaviest rainfall (December–March) and low rainfall (April–November). Infection rates were higher among males (1·59 per 100 person-years) than females (0·92) and lower in blacks (0·98) than other racial/ethnic groups (1·80). A significant trend of decreasing cryptosporidiosis was observed with increasing age, with the highest rate (2·34) in the 13–34 year age group. A strong association between cryptosporidiosis and CD4+ count was noted. These data suggest that cryptosporidiosis among HIV-infected individuals in Los Angeles County exhibits a modest spring and fall seasonality. This pattern of occurrence of cryptosporidiosis appears temporally unrelated to local rainfall patterns. Our findings suggest that HIV-infected men, individuals in younger age groups and those with CD4+ lymphocyte counts <100×106/l are at increased risk of cryptosporidiosis. Blacks with HIV infection appear less likely than other racial/ethnic groups to be diagnosed with Cryptosporidium infection. These results may provide insight into possible routes of transmission and sources of cryptosporidiosis infection in individuals with HIV.

A seroprevalence survey was conducted using ELISA and Western blot (WB) assays for antibody to three Cryptosporidium antigens on 380 blood donors in Jackson County, Oregon. The purpose was to determine if either assay could detect serological evidence of an outbreak which occurred in Talent, Oregon 6 months earlier. The ELISA, which tested for combined IgG, IgA and IgM, and the WB, which tested separately for IgG and IgA, detected an almost twofold increase in serological response for persons who consumed Talent drinking water during the previous 11 months. The increases, however, were statistically significant (P<0·05) only for the WB. The identification of serological evidence of infection, using sera collected 6 months after the end of the outbreak in a population not selected because of cryptosporidiosis-like illness, suggests that assays of Cryptosporidium-specific IgG and IgA may assist in estimating the magnitude of asymptomatic infections in the population.

To estimate the duration of Cryptosporidium-specific antibody, a Western blot assay measured antibody in paired sera from 124 residents of Jackson County, Oregon collected 0·5 and 2·5 years after the end of an outbreak in Talent, Jackson County. The outcome measure was the intensity of antibody responses, (which may approximate to a titre), to 27-kDa and 15/17-kDa antigens. Intensity of response to the 27-kDa antigen(s) declined to 54% of the 1992 value while responses to a 15/17-kDa antigen(s) remained close to the initial values. Increasing age of the donor predicted higher intensity of antibody to the 15/17-kDa antigen(s) in both the initial (P=0·004) and follow-up (P=0·038) surveys. No relationship was observed between age and antibody intensity for the 27-kDa antigen(s) during either survey (P>0·10). Both the initial and follow-up surveys showed significant elevations in antibody intensity for Talent residents, possibly indicating a high endemic rate of infection/re-infection or high levels of chronic infection.

Serpulina pilosicoli was isolated from 8 of 43 (19%) faecal specimens obtained from feral waterbirds sampled around a small lake at Perth Zoological Gardens, Western Australia, and from 3 of 7 (43%) samples of the lake water. The organism was only isolated from 1 of 204 (0·5%) samples from captive birds and animals in the zoological collection. Multilocus enzyme electrophoresis analysis of the isolates showed that they were genetically diverse, and none had identical electrophoretic profiles as those previously obtained from human beings, dogs, pigs and other avian species. To determine the survival time of S. pilosicoli in water, cells of strain 1648 were seeded into lake and tap water, and incubated at 4, 25 and 37°C. The organism could be recultured from lake water for up to 66 days at 4°C, and for 4 days at 25°C. A healthy human volunteer who drank water seeded with S. pilosicoli strain Wes B became colonized, and developed abdominal discomfort and headaches. Contamination of water by faeces may represent a source of S. pilosicoli infection for both humans and animals.

Prevalence of Feline Immunodeficiency Virus (FIV) infection was measured during 6 consecutive years in a natural rural population of domestic cats. Sex, age, weight, origin, group size and presence of antibodies to FIV were recorded for each sampled cat. Logistic regressions were used to estimate the influence of the recorded parameters on infection. FIV prevalence rates are as high as 19·6% in the total population, and do not statistically change between years, after controlling for changes in samples' age structure. FIV infection is characterized by risk factors linked to aggressive behaviour: old mature male adults having dispersed are more likely to be infected. A study of the cats group size and of the spatial distribution of infected individuals indicates the absence of infection clusters in males, and suggests the importance of roaming in the spreading of FIV. In conclusion, FIV infection spreads, with low contagiousness, mainly between particularly aggressive individuals, and the virus is endemic in this population.

Pseudomonas aeruginosa is not generally considered a cause of infectious diarrhoea. However, it was the predominant organism isolated from the faeces of 23 unrelated, hospital outpatients investigated in the course of a year for persistent (>1 week duration) diarrhoea. To investigate the possible aetiological role of P. aeruginosa, these patient histories were reviewed and a selection of their faecal isolates were investigated in vitro (n[ges ]10) and in vivo (n=2) for virulence. The patients had a mean age of 60 years, were receiving antibiotics and/or had an underlying illness. Extensive microbiological investigations identified no other potential or recognized enteropathogen in the faeces of 20 of these patients. More than 40% of the isolates tested were able to adhere to HEp-2 cells and exhibited twitching motility (type IV pili), properties indicative of their ability to colonize the human intestine. Cytotoxic activity was demonstrated in bacterium-free cell supernatants of over 80% of isolates; supernatants of four isolates tested in infant mice were weakly enterotoxigenic. Two isolates intragastrically inoculated into clindamycin pre-treated rats established persistent infections and induced signs and symptoms of enteritis. Overall these findings suggest that P. aeruginosa can cause diarrhoea particularly in immunodeficient individuals.