In 1997, a community-wide outbreak of Salmonella enterica serotype Typhimurium (S. typhimurium) infection occurred in France. The investigation included case searching and a case-control study. A case was defined as a resident of the Jura district with fever or diarrhoea between 12 May and 8 July 1997, from whom S. typhimurium was isolated in stool or blood. One hundred and thirteen cases were identified. Thirty-three (83%) of 40 cases but only 23 (55%) of 42 community controls, matched for age and area of residence, reported eating Morbier cheese (Odds ratio: 6·5; 95% Confidence Interval: 1·4–28·8). Morbier cheese samples taken from the refrigerators of two case-patients and one symptom-free neighbour cultured positive for S. typhimurium of the same phage type as the human isolates. The analysis of distribution channels incriminated one batch from a single processing plant. These findings show that an unpasteurized soft cheese is an effective vehicle of S. typhimurium transmission.

Thirty-nine strains of Salmonella typhi, isolated in 1995 from four Districts in Pakistan, Rawalpindi, Islamabad, Kharian and Jehlem, were catalogued and examined. Chromosomal DNA from each isolate was digested with XbaI restriction endonuclease and subjected to pulsed-field gel electrophoresis. Three clonal variants comprising of 17–19 DNA fragments were identified. Antibiotic susceptibility testing identified that 37 of the S. typhi were resistant to chloramphenicol, trimethoprim and ampicillin. These antibiotic resistance genes were found to be located on one of four plasmids belonging to incompatibility group IncHI1 and ranging in size from 150–175 Kb. The genes responsible for this resistance in each case were the chloramphenicol acetyltransferase (CAT) type I, the dihydrofolate reductase (DHFR) type VII and the β-lactamase TEM-1 respectively.

In this paper we report the distribution of Salmonella Typhi isolates in Italy and their resistance patterns to antibiotics. The data were collected by the Italian SALM–NET surveillance system in a pilot retrospective study of the period 1980–96. Data on drug-resistance were available for 82 isolates out of 176 S. Typhi isolated in Italy. Of these 82 isolates, 32 (39%) were resistant or intermediate to 1 or more antibiotics. Eight isolates were resistant and 7 intermediate to streptomycin; 4 isolates were resistant to ampicillin alone or in association with other antibiotics; only 2 strains (1 isolated in Lombardia in 1993 and the other 1 in Lazio in 1994) were resistant to chloramphenicol, and 2 (isolated in Sardegna and Piemonte in 1995 and 1996, respectively) showed intermediate resistance to chloramphenicol. The strains showing resistance to 3 or more antibiotics were very scarce: 1 (with 5 complete resistances) was isolated in Lazio in 1994, and another 1 (with complete resistance to 10 antibiotics and intermediate resistance to 2 antibiotics) was isolated in Molise in 1988. In conclusion, besides the routine activities to control typhoid fever, an accurate and continuous surveillance is necessary in order to quickly identify multidrug-resistant (MDR) S. Typhi strains and prevent their spread, even though their level, in our country, is still quite low.

Forty-three clinical strains of V. cholerae O1 biotype El Tor were isolated between 3 May and 10 June 1998 during an outbreak in the metropolitan area of Kuala Lumpur and its suburbs. With the exception of three Inaba strains that were restricted to three members of a family, all the others belonged to the Ogawa serotype. The strains were analysed for clonality using ribotyping and pulsed-field gel electrophoresis (PFGE). Two ribotypes, V/B21a and B27, were identified among 40 Ogawa isolates using BglI restriction endonuclease. Ribotype V/B21a has been described previously from Taiwan and Colombia and several Asian countries while B27 has been reported among isolates from Senegal. The three Inaba strains belonged to one ribotype, designated type A, not previously reported. PFGE analysis using NotI revealed that all isolates within a ribotype had identical profiles demonstrating clonality amongst the strains. Dice coefficient analysis of the two Ogawa genotypes revealed 89% similarity on ribotype patterns and 91.3% on PFGE profiles. Ribotype V/B21a isolates were associated with cases from dispersed areas of Kuala Lumpur and its suburbs while ribotype B27 was restricted to cases from one particular area suggesting a common-source outbreak.

During October 1996, an outbreak of Escherichia coli O157[ratio ]H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157[ratio ]H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95% confidence interval = 3·5–infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157[ratio ]H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157[ratio ]H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.

We identified a 5-year outbreak of a methicillin-susceptible Staphylococcus aureus (MSSA) strain, affecting 202 babies on a neonatal unit, by routine weekly phage typing all S. aureus isolates. Multiple staged control measures including strict emphasis on hand hygiene, environmental and staff surveillance sampling, and application of topical hexachlorophane powder failed to end the outbreak. S. aureus PT 53,85 (SA5385) was found on opened packs of Stomahesive®, used as a neonatal skin protectant. Only following the implementation of aseptic handling of Stomahesive®, and the use of topical mupirocin for staff nasal carriers of SA5385, and for babies colonized or infected with S. aureus, did the isolation rate of SA5385 decline. DNA fingerprinting indicated that [ges ]95% of SA5385 isolates were clonal. In vitro death rates of SA5385 on Stomahesive® with human serum were significantly lower than on Stomahesive® alone (P = 0·04), and on cotton sheet with serum (P = 0·04), highlighting the potential of this material as a survival niche. Phage typing remains a valuable, inexpensive and simple method for monitoring nosocomial MSSA infection.

We examined three populations from the Tehran region and the North part of Iran (Gilan), in all more than 5000 individuals, for carriage of Streptococcus pyogenes (group A streptococci; GAS). Children or adults with acute pharyngotonsillitis and healthy school children harboured GAS in 34·1, 20·0 and 21·0%, respectively. Typing of 421 randomly selected isolates showed a predominance of M-types M4, M5, M11, M12, as well as the provisional type 4245; however, many of the isolates were T and M non-typable. Forty-three percent of all strains were opacity factor (OF) negative. The type distribution differed markedly from that reported in 1973–4, when M types 1 and 12 were predominant.

We previously reported an outbreak of vancomycin resistant enterococci (VRE) in a paediatric oncology unit in December 1995 which was associated with widespread environmental contamination of the unit with VRE. We undertook this study to evaluate the effectiveness of the infection control policy instituted subsequent to the outbreak and to investigate the underlying prevalence of VRE colonization in hospitalized, outpatient and community-based children. We sought to establish the molecular similarity of VRE isolates from the study. Stool specimens were obtained from outpatients at risk of VRE, hospital inpatients and from healthy community-based children. VRE colonization was eradicated from the inpatient unit within 11 months, but in outpatients, 16 months after the outbreak, 4 of 137 (2·9%) attending oncology outpatients, 5 of 65 (7·7%) with cystic fibrosis and 1 of 12 (8·3%) with liver disease were found to be colonized with VRE. The isolates were all Enterococcus faecium, Van A phenotype except one E. casseliflavus of the Van C phenotype. All were unique in SmaI DNA macrorestriction patterns with the exception of two isolates, which were similar to the original outbreak strain and three further isolates of a single strain but which differed from the outbreak strain. Of 315 hospital inpatients, 2·5% were colonized with VRE of the Van C resistance phenotype but VRE was not detected in 116 healthy, community-based children. We conclude that effective strategies can successfully control spread of VRE but despite a low prevalence of VRE colonization in hospital patients and in community-based children, outbreaks can occur when infection control practices are not optimal. Continued vigilance to detect VRE and limit spread within hospitals is therefore necessary.

Clostridium perfringens isolates are currently classified into one of five biotypes on the basis of the differential production of α-, β-, ε- and ι-toxins. Different biotypes are associated with different diseases of man and animals. In this study a multiple PCR assay was developed to detect the genes encoding these toxins. In addition, detection of the genes encoding the C. perfringens enterotoxin and β2-toxin allowed subtyping of the bacteria. C. perfringens isolates taken from a variety of animals, including foals, piglets or lambs, were genotyped using this assay. Most of the isolates were found to be genotype A and the gene encoding β-toxin was present in 50% of the isolates genotyped. A significant association between C. perfringens possessing the β2-toxin gene and diarrhoea in piglets was identified, suggesting that β2-toxin may play a key role in the pathogenesis of the disease.

In the week following a carnival during 19–24 February 1998, an outbreak of meningococcal disease occurred in a rural German county. The available isolates belonged to phenotype C[ratio ]2a[ratio ]P1.2,5 and were clonally related by pulsed-field gel electrophoresis. A case-control study was done to identify risk factors for the outbreak and to define possible vaccination target groups. Five persons aged 13–16 years who fell ill during 24–27 February were included in the study. Four of 5 cases and 10 of 32 controls visited local discotheques (OR = 8·8; P = 0·06). Cases also visited discotheques more frequently than controls (χ2 for trend, P = 0·0002). Multiple discotheques during the carnival may have been predominant locations of transmission in this outbreak. Because this risk factor was limited in time, a mass community vaccination campaign was not initiated.

We describe an outbreak of meningitis at a Sudanese refugee camp in Northern Uganda that lasted over a year from February 1994. Some 291 cases occurred in a refugee population of 96860 (averaged over the year), an attack rate of 0·30%. The case fatality rate was 13·3%. From a small number of samples taken for culture N. meningitidis serogroup A, serotype 21[ratio ]P1·9, clone III-1 was identified as the causative organism. The outbreak started in the camp's reception centre which had the highest attack rate. Spread from the reception centre was rapid and the epidemic reached its peak within 3 weeks. All of the cases amongst residents of the reception centre reported having had meningococcal vaccine before arriving at the camp and so were not immunized on arrival as would normally have been the case. Some 37547 doses of meningococcal vaccine were used in a mass immunization campaign in February and March 1994. Following this the outbreak was declared over in August 1994 when no cases were registered for 2 consecutive weeks. However, following a massive and sudden influx of refugees a new epidemic peak occurred during February 1995. Many of these new refugees were also not immunized on arrival due to pressures of numbers. A follow-up immunization campaign then brought an end to the outbreak. Our experience confirms the effectiveness of timely and high-coverage immunization campaigns in controlling group A meningitis outbreaks amongst refugees in Africa.

Fifty-seven bacterial isolates previously identified as Bordetella avium or B. hinzii were characterized by restriction enzyme analysis (REA) and/or ribotyping. Twenty restriction endonucleases were evaluated for REA. Digestion of chromosomal DNA from the 42 B. avium and 15 B. hinzii isolates with Hinf I produced 8 and 7 distinct fingerprint profiles, respectively. Digestion with DdeI further discriminated these Bordetella species and produced 12 fingerprint profiles for B. avium and 4 profiles of B. hinzii. In addition, B. avium isolates were clearly distinguishable from B. hinzii isolates by ribotyping with the restriction endonuclease PvuII. The ribotype patterns of these two species of Bordetella were unique when compared to previously reported ribotype patterns for B. bronchiseptica isolates. Since it was possible to discern differences among isolates within each Bordetella species by REA analysis, we suggest that REA could be used in developing a typing system based on the fingerprint profiles generated.

The predominant H. pylori strain circulating among geographic locations differs with regard to the genomic structure. This study determined whether structural subtypes of the cagA 3′ repeat region could be used to identify the population of origin of H. pylori isolates. We examined 600 cagA-positive H. pylori (Colombia, 100; USA, 100; France, 100; Canada, 20; Italy, 20; Korea, 100; Japan, 100; Hong Kong, 20; Taiwan, 20; Vietnam, 20). The cagA 3′ region was amplified by PCR using primers specific to Japanese and Western 3′ cagA gene sequences. PCR using Japanese cagA primers resulted in PCR products in 99·6% of strains from East Asia but no non-Asian strains. Conversely, PCR using Western cagA primers resulted in amplicons in 100% of non-Asian strains, and only one from East Asia. cagA genotyping is useful for molecular epidemiological studies as strains can be completely separated by differences in the cagA 3′ region.

Reports have suggested that isoniazid treatment may be associated with poor concentration and subtle reduction in memory. This study examines attentional function and processing speed in a group of 25 adolescents who received isoniazid prophylaxis for at least 6 months. As adolescents often face major educational assessment milestones, such cognitive side effects may have important implications. Participants were assessed before treatment, 1 month into treatment and at least 1 week after treatment cessation. Measures included the Paced Auditory Serial Addition Test and subtests of the appropriate Wechsler scale sensitive to attention and speed of information processing. Isoniazid does not appear to cause significant adverse effects on attentional function in adolescents.

Restriction fragment length polymorphism (RFLP) analysis of the amplified P1 gene was used to type 153 strains of Mycoplasma pneumoniae isolated in France between 1977 and 1994, and in Denmark between 1962 and 1994, and an additional group of 28 strains isolated from Belgium and Germany between 1990 and 1993. Random amplified polymorphic DNA (RAPD) analysis was tested on French, Belgian and German strains. Both methods separated the strains into two groups corresponding to the two reference strains M129 (group I) and FH (group II), and gave concordant results. When 75 selected strains of different geographical origin were analysed by pulsed-field gel electrophoresis (PFGE), strains of group II fell into two closely related subgroups, subgroup IIa corresponding to the reference strain FH, and subgroup IIb. Most of the strains isolated in Denmark in the period 1962–86 belonged to group I. Almost all strains isolated in France and Denmark between 1987 and 1988 were from group II, the two subgroups being present. In 1991–3, almost all strains from France as well as Denmark, Germany and Belgium belonged to group I.

Beginning in January 1997, American immunization policy allowed parents and physicians to elect one of three approved infant vaccination strategies for preventing poliomyelitis. Although the three strategies likely have different outcomes with respect to prevention of paralytic poliomyelitis, the extreme rarity of the disease in the USA prevents any controlled comparison. In this paper, a formal inferential logic, originally described by Donald Rubin, is applied to the vaccination problem. Assumptions and indirect evidence are used to overcome the inability to observe the same subjects under varying conditions to allow the inference of causality from non-randomized observations. Using available epidemiologic information and explicit assumptions, it is possible to project the risk of paralytic polio for infants immunized with oral polio vaccine (1·3 cases per million vaccinees), inactivated polio vaccine (0·54 cases per million vaccinees), or a sequential schedule (0·54–0·92 cases per million vaccinees).

Between 22 January and 4 April 1997, 467 hepatitis A cases were reported to the New South Wales Health Department, Australia. To identify the cause of the outbreak, we conducted a matched case-control study, and an environmental investigation. Among 66 cases and 66 postcode-matched controls, there was a strong association between illness and consumption of oysters (adjusted odds ratio 42; 95% confidence interval 5–379). More than two-thirds of cases reported eating oysters, including one third of cases and no controls who reported eating oysters in the Wallis Lake area. A public warning was issued on 14 February, and Wallis Lake oysters were withdrawn from sale. Hepatitis A virus was subsequently identified in oyster samples taken from the lake. Hepatitis A virus poses a special risk to consumers who eat raw oysters because it can survive for long periods in estuaries and cause severe disease.

Since the introduction of routine measles, mumps and rubella immunization for children in England and Wales in 1988, the incidence of mumps has declined steadily. We describe an outbreak of mumps in 1996 attacking 34 of a cohort of 98 schoolchildren born in 1982 and 1983. This is the largest outbreak in the UK since the introduction of the vaccine into the childhood immunization schedule. Salivary IgM assay was used as a simple, minimally invasive test to confirm the diagnosis. The occurrence of the outbreak demonstrates that British children who were just too old to receive mumps immunization in 1988 continue to be at risk of this disease as a result of diminished natural exposure. Further cases and outbreaks in this cohort are to be expected. Cohorts born before 1982 appear to be at less risk, presumably because of naturally acquired infection before the introduction of immunization.

Somalia has suffered from a civil war during the last 10 years. In this period the use of whole blood has increased at least twofold in Mogadishu, Somalia compared with pre-war. Screening possibilities are limited. Recent data concerning the prevalence of infections with blood-borne and sexually transmitted agents are not available from this country. To investigate the spread of human immunodeficiency virus (HIV-1/2) and other blood-borne or sexually transmitted agents we tested a total of 256 serum samples collected in the summer of 1995 from blood donors, hospitalized children and adults in Mogadishu. The hepatitis B surface antigen (HbsAg) carrier rate was 19·1%, 5·6% and 21·3% among blood donors, hospitalized children and hospitalized adults, respectively. However, no children under 2 years of age were HbsAg positive. The overall presence of antibodies against hepatitis C virus (HCV) was 2·4% (6/256). In blood donors this was 0·6% (1/157). In none of the samples tested, antibodies against HIV 1 and 2 or human T-cell lymphotropic viruses (HTLV I and II) were detected. Our results indicate that, during the civil war in Somalia, no evidence of an increase of HIV infections was found. Our findings indicate that preventive measures in Somalia should focus mainly on prevention of HBV-infections. HBV-vaccine could be administered within the framework of the expanded programme on immunization, as none of the children less than 2 years of age were HbsAg positive.

To describe epidemiological features on HIV prevalence among female commercial sex workers (CSWs), a cross-sectional study on sexual behaviour and serological prevalence was carried out in Cambodia. The CSWs were interviewed on their demographic characters and behaviour and their blood samples were taken for testing on sexually transmitted diseases, including HIV, Chlamydia trachomatis, syphilis, and hepatitis B. Associations between risk factors and HIV seropositivity were analysed. High seroprevalence of HIV and Chlamydia trachomatis IgG antibody (CT-IgG-Ab) was shown among the CSWs (54 and 81·7%, respectively). Univariate logistic regression analyses showed an association between HIV seropositivity and age, duration of prostitution, the number of clients per day and CT-IgG-Ab. Especially, high-titre chlamydial seropositivity showed a strong significant association with HIV prevalence. In multiple logistic regression analyses, CT-IgG-Ab with higher titre was significantly independently related to HIV infection. These suggest that existence of Chlamydia trachomatis is highly related to HIV prevalence.