The influence of cytomegalovirus (CMV) infection as a co-factor in HIV-1 disease progression has mainly been studied in haemophiliacs and remains controversial. Based on the files of 1683 HIV-1-infected patients in the Seropositive Cohort (SEROCO) and Haemophiliacs Cohort (HEMOCO) cohorts, we studied the role of CMV infection in progression to CD4+ cell counts of less than 200 μl, AIDS onset and death, in various HIV exposure groups. Adjusted relative risk (aRR) of progression to AIDS and to death was respectively 1·30 (P = 0·05) and 1·58 (P = 0·007). In the sexual exposure group the influence of CMV infection on the risk of progression to AIDS was of borderline significance (aRR = 1·50; P = 0·07) and was more marked on the risk of death (aRR = 2·00; P = 0·03). No such influence of CMV infection was observed in the transfusion and intravenous drug use exposure groups. When we studied the influence of CMV infection according to the stage of HIV disease, the main effect was on progression from AIDS to death, probably because CMV disease is a late event. Sexual CMV transmission and frequent re-exposure to CMV may explain why CMV infection emerged as an important co-factor for HIV progression only in the sexual exposure group.

Eperythrozoon is an obligate parasitic bacteria found in many species of animals. A large scale investigation of the prevalence of Eperythrozoon spp. in humans, was conducted in a developing country using light, electron microscope and animal inoculation. Samples were collected in undeveloped areas of Inner Mongolia in China over a 2-year period of 1994–6. Of the 1529 investigated samples, 35·3% were found to be Eperythrozoon spp. positive. The prevalence of infection was associated with occupation and seasonal variations. The infections were mainly mild, in 89·6% of cases (excluding pregnant women and their children). Of 74 pregnant women tested in the areas of high prevalence, 44 were confirmed Eperythrozoon spp. positive. Similarly, eperythrozoa were found in all 44 umbilical cords tested and in the neonatal peripheral blood samples taken at birth. These data suggest that eperythrozoa can be transmitted via the placenta.

Lung and intestine of 49 pigs with respiratory diseases and endocervical swabs from 205 sows with reproductive disorders were investigated for chlamydial infection by polymerase chain reaction. PCR primers targeted DNA sequences on the chlamydial omp1 or omp2 genes. PCR amplicons were generated from 49·0% of pigs with respiratory disease, from 60·0% of sows with reproductive disorders, from 24·5% of respiratory healthy controls, but from no endocervical swabs from fertile sows. By DNA hybridization, a high prevalence of mixed infections with Chlamydophila abortus and Chlamydia suis in the porcine lung and intestine was found and confirmed by RFLP and nucleotide analysis. Of the omp1-PCR amplicons from endocervical swabs 81·3% were identified as Chlamydophila abortus, indicating an association of this chlamydial species with reproductive disorders in sows. Nucleotide sequence analysis of omp1-amplicons identified as deriving from Chlamydia suis shared a maximum of 82·7% homology with the reference strain S45.

This is a long-term study that investigates the dynamics of a population of Rattus norvegicus (Berk) inhabiting a sewerage system in London. Thirteen years (1986/7–1998/9) of data from sewer baiting records were analysed (a total of 35478 records). Manholes were baited with the anticoagulant Brodifacoum (0·005%) on a pinhead oatmeal bait base. Time series analysis was conducted on the data set to determine the underlying trend of the data and the population fluctuations about this trend. An exponential curve was found to give an accurate and realistic fit to the data and indicated that the rat population had decreased over the study period. Decomposition analysis indicated a 5-year cycle best described fluctuations around this trend.

Samples from 2427 cattle, 661 goats, 104 sheep, 98 camels and 82 horses were screened for brucella infections by the Rose Bengal Test and positive reactors confirmed by the complement fixation test. In cattle, the highest individual seroprevalence was in dairy herds kept under the intensive husbandry system, with an individual prevalence of 8·2% and unit (herd) seroprevalence of 35·9%. This was followed by the pastoral husbandry system in the Western Lowlands with 5·0% individual but a higher unit (vaccination site) prevalence of 46·1%. The lowest was in the mixed crop-livestock system in the Southern Highlands with individual 0·3% and unit (village) prevalence of 2·4%. In sheep and goats, no positive animals were detected in the mixed crop-livestock areas. In the Eastern Lowlands individual prevalences of 3·8% (goats) and 1·4% (sheep) and unit prevalence of 33·3% (goats) and 16·7% were found, while 14·3% of individual goats and 56·3% of the units in the Western Lowlands were positive. No positive horses were found. The present study documents the first serological evidence of Brucella spp. infection in camels (3·1%) in Eritrea.

EEC directive 76/160 requires member states to apply microbiological and chemico-physical standards for the quality of recreational waters. In observation of this regulation, in the present study 144 samples of seawater were taken over a 12-month period and tested to determine viral contamination. The samples were collected from the coastal waters of the Italian town of Pesaro, which is located on the Adriatic Sea. Using cell culture techniques, 32·6% of the seawater samples were found to be contaminated with enteroviruses. Isolation of these viruses was most frequent in the summer months. Thus, our results indicate the need to increase the frequency of monitoring of these waters and to eliminate the sources of contamination.

The fact that a substantial proportion of tuberculosis drug resistance (especially multidrug resistance) is due to transmission of resistant strains or treatment failure in the UK underlines the need to strengthen control in this country. Early identification and effective treatment of cases (including measures to support adherence and appropriate use of initial treatment regimes involving at least four drugs in those at risk of isoniazid resistance) would help to control the problem [1].