The diagnosis of maternal infection in early pregnancy depends on tests which are sensitive to recent infection, such as specific IgM. Two types of test are considered: those where the response persists for a period following infection and then declines, such as IgM. and those whose response increases with time since infection, such as IgG-avidity. However, individuals vary in their response to infection, and it may not always be possible to determine whether an infection occurred during pregnancy or before it. Mathematical methods are developed to evaluate the performance of these tests, and are applied to the diagnosis of toxoplasmosis in pregnancy. It is shown that, based on existing information, tests of recent infection are unlikely to be both sensitive and predictive. More data on these tests are required, before they can be reliably used to determine whether infection has occurred during pregnancy or before it.

A total of 123 drug-resistant and drug-sensitive Shigella flexneri types 1–6, and their Escherichia coli K12 transconjugants were used for plasmid profile analysis by agarose gel electrophoresis. Resistance factors (R-factors) were further characterized by incompatibility testing.

The overall distribution of small plasmids in S. flexneri showed that a cryptic plasmid of about 4·6 Kb was found in all serotypes, and a plasmid of about 4·2 Kb was found in serotypes 1–4. Shigella flexneri types 2, 4 and 6 showed a 6·5 Kb plasmid which correlated with SSu-resistance. All S. flexneri serotypes harboured large plasmids of about 217 Kb. Plasmid profile analysis of S. flexneri in Ethiopia showed a high degree of uniformity within individual serotypes. However, there was a limited variability which, at times, could be useful for epidemiological investigation. Shigella flexneri serotypes 1–6 harboured resistance plasmids with diverse molecular weights but mostly belonging to incompatibility groups N and X.

Before Gregg's historic observation [1] rubella was not considered to have clinical or epidemiological importance in any country. In the western world epidemics occurred at varying intervals but with little morbidity and apparently only minor complications. Despite confirmation of Gregg's findings from many quarters, it was not until the worldwide outbreaks in the 1960s that the aftermath of rubella infection in pregnancy was fully realized. As a result of the 1964 outbreak in New York City, more than 1000 children were born with congenital rubella syndrome (CRS) and over 300 pregnancies either aborted spontaneously or were terminated for rubella infection [2]. The number of children affected represented 1% of births in the city; if extrapolated to the whole country this gave an estimated total of 30000 cases of CRS. No such disasters have so far been reported from the developing world.

The population structure and transmission of Escherichia coli in a small group of individuals isolated for 26 weeks on an Antarctic base were studied by multilocus electrophoresis of eight enzymes and plasmid analysis. Two hundred and sixty-nine strains were isolated. They were grouped into 60 allozyme types (ETs). Half of these ETs were only isolated once; others were repeatedly isolated from single subjects. Eleven were found in more than one subject and the pattern of the occurrence of some of them was considered to provide evidence of their spread from subject to subject.

Using ordinary least squares regression techniques this paper demonstrates, for the first time, that the classic association of war and disease substantially accounts for the presently observed geographical distribution of reported clinical AIDS cases in Uganda. Both the spread of HIV 1 infection in the 1980s, and the subsequent development of AIDS to its 1990 spatial pattern, are shown to be significantly and positively correlated with ethnic patterns of recruitment into the Ugandan National Liberation Army (UNLA) after the overthrow of Idi Amin some 10 years earlier in 1979. This correlation reflects the estimated mean incubation period of 8–10 years for HIV 1 and underlines the need for cognizance of historical factors which may have influenced current patterns of AIDS seen in Central Africa. The findings may have important implications for AIDS forecasting and control in African countries which have recently experienced war. The results are compared with parallel analyses of other HIV hypotheses advanced to account for the reported geographical distribution of AIDS in Uganda.

This study presents the findings of a national survey of 1482 cases of salmonellosis reported to Environmental Health Departments in England and Wales between August 1988 and March 1989. A questionnaire survey of ill individuals and the environmental health officers who investigated them sought information about costs which were imposed upon public health authorities, the health sector, individuals and their families and the costs to the wider economy in terms of lost production.

Costs of £996339 were identified. Over half (£507555) resulted from lost production due to sickness absence and more than a third (£392822) were costs to the public sector which resulted from health care and local authority investigation of cases. The remaining costs (£95962), although the smallest proportion of the total, indicated that salmonellosis can have a significant impact on affected individuals and their families.

Genotypic and phenotypic analysis of 42 strains of Streptococcus uberis isolated from mammary secretions of 17 cows collected at different periods of the lactation cycle and from episodes of clinical mastitis were performed. Seventeen restriction endonuclease fingerprint (REF) patterns and 12 bacteriocin-like inhibitory substance (BLIS) fingerprints were observed. REF identified and differentiated closely related strains of S. uberis isolated from mammary secretions collected from the same cow at different periods of the lactation cycle and from episodes of clinical mastitis. BLIS fingerprinting of S. uberis complemented REF results. REF and BLIS fingerprinting provided evidence concerning persistence of infection in the same quarter or different quarters of the mammary gland over different periods of the lactation cycle, and occurrence of infection with similar and dissimilar strains of S. uberis. Biochemical profiles could not identify closely related strains nor did they complement REF results. Antibiotic resistance patterns alone were of little value in differentiating closely related strains, but were identical with isolates having same REF pattern. None of the S. uberis strains was found to carry plasmids. REF and BLIS fingerprinting can be utilized effectively to differentiate closely related and unrelated strains of S. uberis isolated from bovine mammary secretions.

Sera from patients with yersiniosis. shown to contain antibodies to Yersinia enterocolitica O9; and sera from patients with haemolytic uraemic syndrome (HUS) caused by Escherichia coli O157, were used to investigate serological cross-reactions between Y. enterocolitica O9 and E. coli O157. Lipopolysaccharide (LPS) was isolated from strains of Y. enterocolitica O9 and E. coli O157 and reacted with sera by immunoblotting and ELISA. Sera from patients with HUS contained antibodies to the LPS of E. coli O157 only; 80% of sera from patients with yersiniosis contained antibodies to the LPS of Y. enterocolitica O9 and E. coli O157. This one-way cross-reaction was also detected using hyperimmune rabbit antisera.

This study included 502 staphylococcus strains; Staphylococcus saprophyticus (297 strains) S. cohnii (47), S. xylosus (10), S. epidermidis (67) and S. aureus (81). Mitomycin C induction was performed on 100 isolates of S. saprophyticus and all induced strains were reacted with each other. Twenty-six strains proved to be lysogenic. Phages were propagated and titrated. With 12 of the phages there were three frequent associations, named lytic groups A, B and C, which included 75% of all typable strains. Typability of the system was 45% and reproducibility was between 94.2% and 100%. Phages did not lyse S. aureus and S. epidermidis strains, but they lysed S. saprophyticus and only rare strains of other novobiocin resistant species. Effective S. saprophyticus typing serves ecological purposes and tracing the origin of urinary strains from the skin or mucous membranes. Phage typing in association with plasmid profiling previously described, are anticipated as complementary methods with strong discriminatory power for differentiating among S. saprophyticus strains.

In March 1989 a large outbreak of acute gastroenteritis occurred simultaneously among schoolchildren and teachers at nine elementary schools in Toyota City, Japan. Illness was observed in 3236 (41·5%) of 7801 schoolchildren and 117 (39·4%) of 297 teachers. The main clinical symptoms were diarrhoea, vomiting, nausea and abdominal pain. Gastroenteritis was significantly associated with the consumption of school lunch served by one particular lunch preparation centre. One food handler at the centre suffered from gastroenteritis during the outbreak.Small round structured virus (SRSV) was detected in 4 of 8 stool specimens from sick persons. The school lunch contaminated by the infected food handler is the most probable source of this outbreak due to SRSV.

Characterization of 169 strains of Salmonella typhi of phage types C1, C4, D1 and D9 isolated in 1975–88 was carried out by rDNA gene restriction pattern analysis. Twenty-four isolates had been recovered during four large waterbone outbreaks in the last 20 years in Sicily; 145 strains, isolated from apparently sporadic cases of infection in Southern Italy in the same period of time, were also examined.

Application of rRNA–DNA hybridization technique after digestion of chromosomal DNA with Cla I showed the identity of patterns of the epidemic strains of phage types C1 and D1, confirming attribution of the outbreaks to single bacterial clones. Patterns of the two available strains of lysotype D9 were slightly different, whilst the 12 epidemic strains of phage type C4 could be assigned to two distinct patterns scarcely related to each other and, consequently, to two different clones. A considerable heterogeneity was detected among all apparently sporadic isolates of the four phage types under study.

This fingerprinting method appears a reliable tool to complement phage typing in characterizing isolates of S. typhi. In particular, epidemiological features of spread of this salmonella serovar in areas, where simultaneous circulation of indigenous and imported strains occurs, can be elucidated.

A group specific agar-gel immunodiffusion test was used to demonstrate that there is a frequent and widespread distribution of bluetongue virus throughout the Sultanate of Oman. The Culicoides midges C. imicola and C. schultzei, both capable of transmitting bluetongue group viruses, were recorded throughout the year. Although these studies did not establish that bluetongue is enzootic in Oman, type-specific neutralizing antibody results supported previous evidence for the existence of a Saudi Arabian bluetongue ecosystem. Variations in antibody evidence of virus activity within a restricted locality suggested a hot-spot theory concerning the perpetuation of the virus.

A total of 221 cockroaches (Blatta and Periplaneta spp.), collected in hospitals, houses, animal sheds, grocery stores and restaurants, in yarious parts of South Kanara District, a south-west coastal region of India, were studied bacteriologically for the presence of various salmonellas. Salmonellas were isolated from 4·1% of these cockroaches. Nine strains of salmonellas were recovered, belonging to five serotypes – Salmonella bovismorbificans, S. oslo, S. typhimurium, S. mbandaka and S. braenderup, the former two being the commonest serotypes. All salmonellas were resistant to one or other of 11 antibacterial drugs used in the susceptibility test. Isolation of salmonellas from cockroaches collected from the livestock premises and human dwellings suggested that they may act as significant reservoirs of salmonella in nature. Recovery of serotypes, phage types and R- types that were commonly isolated from humans and animals of this locality, suggested a transmission role for cockroaches. By harbouring potentially pathogenic, drug-resistant salmonellas, these wandering arthropods may pose dangerous infective hazards to humans and animals.

The indirect haemagglutination (IHA) test using sensitized turkey erythrocytes and the indirect immunofluorescence assay (IgM-IFA) was confirmed to be sensitive in the detection of a recent or current Pseudomonas pseudomallei infection in 19 culture-confirmed Singapore melioidosis patients. All were found to have antibody titres from 4 to 32 768 in the IHA test and 10 to 320 in the IgM-IFA test. When these tests were employed on sera from 16 immigrant Thai construction workers who died of sudden unexplained death syndrome (SUDS) and 73 healthy Thai fellow workers, 93·8% and 68·8% of SUDS cases had IHA titre of ≥ 4 and IgM-IFA titre of ≥ 10 respectively, in contrast to 39·7% and 12·3% found among healthy Thai workers. These data indicate that at the time of death, most of the SUDS patients had an active infection with P. pseudomallei, possibly resulting from reactivation of a latent infection. The aetiological role of P. pseudomallei as the major cause of SUDS is discussed.

Faecal oral spread is claimed by many to be the mode of transmission of the gastric pathogen Helicobacter pylori. This idea is based not on experimental data but because the epidemiology of H. pylori infection resembles that of other pathogens known to be spread by the faecal-oral route. This is in spite of the observation that no-one has been successful in culturing H. pylori from human stool. In this study, a series of transmission experiments are reported on animals infected with the gastric spirilla, Helicobacter felis and ‘Gastrospirillum hominis’. Germfree mice and rats infected with H. felis did not transmit their infection to uninoculated mice despite prolonged contact in the same cage nor could the bacterium be isolated from their intestinal contents. This was confirmed in specific pathogen free mice where infected dams did not pass the helicobacter to their progeny. Similarly, mice infected with a human isolate of ‘Gastrospirillum hominis’ did not transmit the infection while in close contact with uninoculated mice. In contrast, in a limited series of experiments, both H. pylori and H. felis were transmitted from infected gnotobiotic Beagle puppies to uninfected animals in the same enclosure. In addition, the gastric mucus from a cat with indigenous ‘Gastrospirillum’-like organisms was infectious for mice, whereas faecal content from the same animal was not. It is suggested that the difference between the murine and canine experiments is that the dogs are more likely to have oral-oral contact than rodents. Unlike dogs, mice and rats do not vomit and are coprophagous. It is concluded that the case for faecal-oral spread of Helicobacter species is ‘not proven’ and that the inter-oral route is more likely.

In 1990 we reported that milk bottles pecked by jackdaws and magpies were a probable source of human Campylobacter infection. During April to June 1990 an extended study of Campylobacter infections was carried out in the Gateshead area. Prior to the study a health education programme was undertaken in an attempt to reduce human infection. Fifty-nine cases of human infection were recorded and 52 were interviewed. Thirty were entered into a case control study which demonstrated a very strong association between consumption of pecked milk and human Campylobacter infection (X2 = 12·6, P < 0·0004). It was estimated that between 500 and 1000 jackdaws (Corvus monedula) were present in the area where milk bottles were pecked and 63 isolates of Campylobacter were made from the bill and cloaca. Target bottles were put out in the early mornings and Campylobacters were isolated from 12 of 123 pecked bottles. Typing of the Campylobacters revealed a wide distribution of strains amongst birds, pecked milk and human infections. The health education programme had only limited success.

In an attempt to explain the recent resurgence of homosexually-acquired gonorrhoea in the Lothian region of Scotland the number of infections and pattern of infection (urethral, rectal and pharyngeal) of all gonococcal isolates from homosexual men attending the Department of Genitourinary Medicine at Edinburgh Royal Infirmary between 1985 and 1990 were analysed. Serovar typing data were available from infections acquired between January 1986 and December 1990. A correlation between one serovar, Bacejk/Brpyust, and the overall pattern of gonorrhoea was observed. The number of infections caused by minor serovars also correlated with rates of gonococcal infection. The number of minor serovars isolated, which may represent strains from other geographical locations, is related to the total incidence of gonorrhoea. It is possible that the incidence of Bacejk/Brpyust may be determined by the size of the infected pool of gonorrhoea. The most likely explanation for the recent increase in gonorrhoea is a change in sexual behaviour and/or an influx of strains from other geographical areas.

Samples of 216 pâatés were examined for the presence of Listeria spp. Between May and August 1989; 35% were contaminated with L. monocytogenes, 5% of samples having counts of > 104/g. L. innocua was recovered from 2% of samples but no other species was isolated. Five serotypes of L. monocytogenes were represented (1/2, 4b, 4b(X), 4 not 4b or 4b(X), and NT). 4b was the predominant serotype and multiple serotypes were found in eight pâatés. The incidence of contamination with L. monocytogenes was greater in stored pâté (46%) than display pâté (30%). Sampling over a 21-day period showed an apparent increase in numbers of L. monocytogenes in 6 of 7 samples with multiple serotypes represented. There was no correlation between contamination of pâté by L.monocytogenes and the presence of coliforms. Comparisons are made between the contamination of soft cheese and pˇaté.

An outbreak of infection caused by a previously undescribed Gram-negative bacterium affected people attending a hot (37 °C) spring spa in France in 1987. Thirty-five case of pneumonia and two cases of meningitis occurred. None of these patients died. Attack rates were significantly higher for patients above 70 years old and for male patients. An epidemiological comparison of the 26 hospitalized eases with 52 matched controls suggests that spa treatment early on the first day (OR = 4·8) and attendance at the vapour baths (OR = 10·7) were significant risk factors for acquiring the infection. Person-to-person spread was not thought to have occurred. The same bacterium was isolated from the hot spring water. All strains studied shows a single rRNA gene restriction pattern. Epidemiological data indicated that the thermal water was the source of infection. This outbreak stresses the need for increased surveillance of infections in people attending hot spring spas.

In a setting where potable water is contaminated with Legionella pneumophila serogroup 1, we performed two case control studies. The first case control study consisted of 17 cases of nosocomial Legionnaires' disease (LD) and 33 control (the patients who were admitted to the ward where the case was admitted immediately before and after the case) subjects. Cases had a higher mortality rate 65% vs 12% (P < 0.004); were more likely to have received assisted ventilation (P < 0.00001); to have nasogastric tubes (P < 0.0004) and to be receiving corticosteroids or other immunosuppressive therapy (P < 0.0001). Based on the results of this study, sterile water was used to flush nasogastric tubes and to dilute nasogastric feeds. Only 3 cases of nosocomial LD occurred during the next year compared with 12 the previous year (P < 0.0001). Nine cases subsequently occurred and formed the basis for the second case-control study. Eighteen control subjects were those patients admitted to the same unit where the case developed LD, immediately before and after the case. The mortality rate for the cases was 89% vs 6% for controls (P < 0.00003). The only other significant difference was that cases were more likely to be receiving corticosteroids or other immunosuppressive therapy 89% vs 39% ( < 0.01). We hypothesized that microaspiration of contaminated potable water by immunocompromised patients was a risk factor for nosocomial Legionnaires' disease. From 17 March 1989 onwards such patients were given only sterile potable water. Only two cases of nosocomial LD occurred from June 1989 to September 1990 and both occurred on units where the sterile water policy was not in effect. We conclude that aspiration of contaminated potable water is a possible route for acquisition of nosocomial LD in our hospital and that provision of sterile potable water to high risk patients (those who are receiving corticosteroids or other immunosuppressive drugs; organ transplant recipients or hospitalized in an intensive care unit) should be mandatory.