Time trends and geographical variation of Helicobacter pylori antibodies in Finland were investigated by enzyme immunoassay in 20- to 34-year-old randomly selected females from six localities during 1969–73 (n = 375), and 15- to 45-year-old females representing nine communities and four geographical areas in 1983 (n = 882) and 1995 (n = 842). In the six communities investigated at three different time points, the overall prevalence declined from 38 to 12%, with an emphasis on the latter 12 years. The regionally varying rate of decrease in helicobacter prevalence changed the pre-existing geographical variation, leaving northern Finland with the highest rate. A 10%-units higher local helicobacter prevalence seemed to predict a 23% (95% CI 3–44%) higher gastric cancer incidence 20 years later. The overall decline in helicobacter seropositivity is consistent with earlier reports from Finland and other developed countries, and supports the cohort theory as an explanation for the age-related increase in H. pylori seroprevalence.

Though it is recognized that the extent of ‘clustering’ of isolates from tuberculosis cases in a given population is related to the amount of disease attributable to recent transmission, the relationship between the two statistics is poorly understood. Given age-dependent risks of disease and the fact that a long study (e.g. spanning several years) is more likely to identify transmission-linked cases than a shorter study, both measures, and thus the relationship between them, probably depend strongly on the ages of the cases ascertained and study duration. The contribution of these factors is explored in this paper using an age-structured model which describes the introduction and transmission of M. tuberculosis strains with different DNA fingerprint patterns in The Netherlands during this century, assuming that the number of individuals contacted by each case varies between cases and that DNA fingerprint patterns change over time through random mutations, as observed in several studies.

Model predictions of clustering in different age groups and over different time periods between 1993 and 1997 compare well against those observed. According to the model, the proportion of young cases with onset in a given time period who were ‘clustered’ underestimated the proportion of disease attributable to recent transmission in this age group (by up to 25% in males); for older individuals, clustering overestimated this proportion. These under- and overestimates decreased and increased respectively as the time period over which the cases were ascertained increased. These results have important implications for the interpretation of estimates of the proportion of disease attributable to recent transmission, based on ‘clustering’ statistics, as are being derived from studies of the molecular epidemiology of tuberculosis in many populations.

Ciprofloxacin-resistant gonococci have been isolated from patients in the United Kingdom since 1993. Until recently, evidence has suggested that the majority of infections are not endemic but have been acquired abroad. In October 1999, increasing numbers of ciprofloxacin resistant isolates of the non-requiring auxotype were reported in Oldham and Rochdale (Northwest England). These and similar isolates from elsewhere in England and Wales were genetically characterized using a simplified opa-typing method (a non-radioactive PCR–RFLP method targeting the opa family of genes). Of 73 isolates studied, 24 had unique opa-types (10 from infections acquired abroad), whilst the remaining 49 were indistinguishable (none were known to be acquired abroad). This cluster included 31 isolates from Oldham and Rochdale, 16 from elsewhere in the north of England, and 2 from Southern England and South Wales with known epidemiological links to cases from Manchester and Rochdale respectively. This study illustrates the potential for spread of an antibiotic resistant clone of N. gonorrhoeae both locally and nationally and demonstrates that endemic acquisition of ciprofloxacin-resistant gonococci is now a significant problem in the United Kingdom.

From December 1997 to April 1998, 1060 laboratory-confirmed cryptosporidiosis cases were reported in New South Wales, Australia. In a case-control study, compared with 200 controls, the 100 cases were younger (mean age 4·2 versus 7·1 years; P < 0·0001), more likely to report swimming at a public pool (59% versus 38%; adjusted OR and 95% CI = 2·7; 1·4–5·1) and swimming in a dam, river or lake (OR = 4·8; 1·1–20·3) but less likely to report drinking bottled water (OR = 0·4; 0·2–0·9). In subgroup analyses, in rural areas illness was associated mainly with contact with another person with diarrhoea, and in urban areas illness was associated with swimming in a public pool. Cryptosporidium oocysts were more commonly detected in pools to which at least two notified cases had swum (P = 0·04). Outbreaks of cryptosporidiosis can be prolonged, involve multiple pools and be difficult to control.

Invasive fungal infections are becoming an increasing public health problem owing to the growth in numbers of susceptible individuals. Despite this, the profile of mycoses remains low and there is no surveillance system specific to fungal infections currently existing in England and Wales. We analysed laboratory reports of deep-seated mycoses made to the Communicable Disease Surveillance Centre between 1990 and 1999 from England and Wales. A substantial rise in candidosis was seen during this period (6·76–13·70 reports per million population/year), particularly in the older age groups. Rates of cryptococcosis in males fluctuated over the decade but fell overall (1·05–0·66 per million population/year), whereas rates of female cases gradually rose up until 1998 (0·04–0·41 per million population/year). Reports of Pneumocystis carinii in men reduced substantially between 1990 and 1999 (2·77–0·42 per million population/year) but showed little change in women. Reports of aspergillosis fluctuated up until 1996, after which reports of male and female cases rose substantially (from 0·08 for both in 1996 to 1·92 and 1·69 per million population/year in 1999 for males and females respectively), largely accounted for by changes in reporting practice from one laboratory. Rates of invasive mycoses were generally higher in males than females, with overall male-to-female rate ratios of 1·32 (95% CI 1·25–1·40) for candidosis, 1·30 (95% CI 1·05–1·60) for aspergillosis, 3·99 (95% CI 2·93–5·53) for cryptococcosis and 4·36 (95% CI 3·47–5·53) for Pneumocystis carinii. The higher male than female rates of reports is likely to be a partial reflection of HIV epidemiology in England and Wales, although this does not fully explain the ratio in infants and older age groups. Lack of information on underlying predisposition prevents further identification of risk groups affected. Whilst substantial under-reporting of Pneumocystis carinii and Cryptococcus species was apparent, considerable numbers of superficial mycoses were mis-reported indicating a need for clarification of reporting guidelines. Efforts to enhance comprehensive laboratory reporting should be undertaken to maximize the utility of this approach for surveillance of deep-seated fungal infections.

Objective: To identify risk factors for infectious intestinal disease (IID) due to rotavirus group A in children aged under 16 years.

Methods: Case-control study of cases of IID with rotavirus infection presenting to general practitioners (GPs) or occurring in community cohorts, and matched controls.

Results: There were 139 matched pairs. In children under 16 years the following risk factors were significantly associated with rotavirus IID: living in rented council housing (adjusted OR=3·78, P=0·022), accommodation with more than five rooms (OR=0·72, P=0·002), contact with someone ill with IID (OR=3·45, P<0·001). Some foods were associated with decreased risk. In infants, bottle feeding with or without breast feeding was associated with increased risk (OR=9·06, P<0·05).

Conclusions: Contact with persons with IID, living in rented council housing and accommodation with fewer rooms, were significant risk factors for sporadic rotavirus IID in children whereas breast feeding is protective in infants.

The degree of seroprotection against diphtheria in Poland was evaluated by determination of IgG antibodies to Corynebacterium diphtheriae toxin (IgG-DTAb). The study population consisted of 4829 healthy subjects aged from 1 day to 85 years from 7 regions of Poland. Serum samples collected between 1996 and 1998 were assayed for IgG-DTAb antibodies using a toxoid enzyme immunoassay. Neutralization of toxin in Vero cells was performed as a reference method with the WHO standard for human diphtheria antitoxin. The study revealed a lack of seroprotection (IgG-DTAb < 0·1 IU/ml) in 23 % of individuals, basic seroprotection (0·1–1·0 IU/ml) in 64 %, and effective seroprotection (> 1·0 IU/ml) in 13 %. The non-protected group consisted of non-vaccinated children below 2 months of age (10 %), individuals between 2 months and 18 years old (20 %) and greater than 19 years old (70 %). Of the adults, 32 % were seronegative, 63 % had basic seroprotection and only 5 % were fully protected; 43 % of adults between 30 and 64 years, who had not been vaccinated at least during the previous 10 years were not protected against diphtheria. The geometric mean titre (GMT) of IgG-DTAb was 0·25 IU/ml in the total population. Age-related GMTs differed significantly from each other and were higher (0·44 IU/ml) in individuals from 2 months to 18 years old, compared with 0·14 IU/ml and 0·17 IU/ml in children under 2 months and adults, respectively. No significant difference was found in the GMTs of men and women in all age groups. We conclude that the currently used vaccination programme in Poland is highly effective and assures protection against diphtheria in the majority of the population in the 10-year period following the last booster. However, a significant proportion of adults between 30 and 64 years lack protection and this indicates a need for booster immunization for this group.

Objectives: To study the association between community influenza activity and acute hospital admissions for pneumonia and influenza among elderly persons.

Design: Multiple regression analysis of acute hospital admissions against community influenza activity, air temperature and seasonal and long-term trends.

Setting: Three English health districts: 1987–95.

Subjects: Persons aged [ges ]65 years.

Outcome measures: Acute hospital admissions for pneumonia and influenza (ICD9: 480–487); excess hospital admissions during epidemic periods.

Results: The final regression model explained 70% of the total variation in hospital admissions for pneumonia and influenza, including 14% due to community influenza activity. However, most variation was explained by long-term and seasonal changes unrelated to influenza. In the large influenza epidemic of 1989/90 a typical health district (500000 total population) experienced 56 excess admissions for pneumonia and influenza attributable to epidemic influenza among persons aged [ges ]65 years, requiring 672 additional bed-days. However the figure varied widely between seasons and over the whole study period, the average winter excess was 17·5 admissions per health district, requiring an additional 210 bed-days.

Conclusions: Influenza epidemics exert a variable impact on acute hospital admissions for pneumonia and influenza among elderly persons, which in the past have been poorly quantified. Although the absolute numbers of excess admissions is modest, their impact on bed availability may be considerable because of the duration of hospital stay in elderly persons.

Two cases of legionellosis occurring 3 years apart were acquired in the same French thermal spa and were apparently due to the same strain of Legionella pneumophila serogroup 1, as shown by genomic macrorestriction analysis. Minor differences between the two isolates were found by random amplification PCR profiling which showed an additional band with one of the isolates. Analysis of 107 L. pneumophila strains isolated from the spa waters by genome macrorestriction failed to identify the infective strain, but a closely related L. pneumophila serogroup 3 strain differing from the clinical isolates by only one band was found. To determine if the clinical L. pneumophila serogroup 1 isolates was better adapted for intracellular multiplication than related serogroup 3 environmental isolates, the growth kinetics of six isolates were determined in co-culture with Acanthamoeba lenticulata. One clinical isolate failed to grow within amoeba, while the other clinical isolate yielded the highest increase in bacterial cell count per amoeba (1200 %) and the environmental isolates gave intermediate values. Genetic analysis of L. pneumophila isolates by DNA macrorestriction does not therefore appear to reflect their growth kinetics within amoeba, and is not sufficiently discriminatory to identify potentially virulent strains.

Restriction fragment length polymorphism (RFLP) analysis and partial-genome DNA sequencing are commonly used to infer genetic relationships among pathogens. This study compares the application of both techniques to the analysis of 16 pseudorabies virus isolates collected during a 1989 outbreak. Genetic distances derived from RFLP and DNA sequence data were not significantly correlated with geographic distances between farms from which isolates were collected. RFLP-based genetic distance was, however, strongly correlated with temporal distance between isolates (days separating time of isolation). Sequence-based genetic distance was significantly correlated with temporal distance only when synonymous changes (nucleotide changes not leading to amino acid changes) were considered separately. Conversely, non-synonymous changes were correlated with the host species of origin of the viral isolate. These results indicate that selectively-neutral genetic changes most accurately reflect historical relationships, but that non-neutral changes most accurately reflect the biological environment of the viral isolate (e.g. host immune system).

We conducted an epidemiological study of a Japanese encephalitis (JE) outbreak in the southwestern part of Nepal in 1997. A high density of JE infections was found and it was estimated that 27·9% the total population were infected with JE virus in the study area. The fatality rate was 13·2% and there was no difference in the fatality rate between males and females over 5 years old. However, the case fatality rate was 2·1 times higher in females than in males (14·6% vs. 6·9%) among children under 5 years of age. Fifty-three blood samples were collected from suspected JE cases during the epidemic period in 1998. Findings for JE specific IgM revealed that clinical diagnoses of JE were serologically confirmed in an average 78% (70–93%) of patients in three collaborating hospitals. These studies demonstrated that JE was highly prevalent in the area and clinical diagnoses were reliable. Effective preventive measures should be taken against this vaccine-preventable disease.

In April 1999, an outbreak of Pontiac fever occurred at a hotel in Northern Sweden. A retrospective cohort study to find the source and define the extent of the outbreak was carried out among 530 Swedish and Norwegian guests. Twenty-nine epidemiological cases (8 % of 378 responders) aged 21–57 years were identified. Antibodies against Legionella micdadei were detected in 17 of 27 tested cases and 3 other symptomatic persons. Visiting the whirlpool area was identified as the sole risk factor (RR 86; 95 % CI 21–352) and infected cases were confined to visitors to this area over three successive days. The attack rate was 71 % (27/38) and 24 cases (83 %) used the whirlpool. Environmental sampling was negative for Legionella sp. But epidemiological investigation strongly suggests that the whirlpool was the source of the outbreak. The possibility of serious legionella infections underlines the importance of strict maintenance practices to maintain hygiene of whirlpools.

In 1998, an outbreak of gastroenteritis affected at least 448 persons including 122 staff at a resort hotel in Bermuda. A survey among staff indicated that gastroenteritis was associated with eating or drinking at the hotel (OR = 6·0, 95% CI = 2·4–15·1). Multiple specimens of drinking water had elevated faecal coliform levels and Escherichia coli present, suggestive of faecal contamination. Stools from 18 of the 19 persons with gastroenteritis that were tested were positive for genogroup-II Norwalk-like viruses (NLVs). RT–PCR analysis of a 3 l specimen of water produced a genogroup-II NLV genome with a sequence identical to that of NLVs in the stools of three ill persons. This outbreak shows the value of new molecular diagnostics to link illness with a contaminated source through the use of sequence analysis. The risk of outbreaks such as these could be reduced in tourism dependent regions like Bermuda and the Caribbean by regular evaluation of data from the inspection and monitoring of drinking water supplies and waste water systems, by ensuring the chlorination of supplemental drinking water supplies and by establishing food-safety initiatives.

The European Regional Office of WHO has targeted measles for elimination from the region in 2007. Large national, age and sex stratified serological surveys of measles antibody were conducted in seven Western European countries from 1994–8 as part of the European Sero-epidemiology Network. Three patterns were observed in the country-specific measles seroprofiles, ranging from (very) low susceptibility (four countries) to high susceptibility (one country). Susceptibility levels amongst 2–4-year-olds ranged from 2·9 to 29·8 %, in 5–9-year-olds from 2·5 to 25 % and 10–19-year-olds from 2·1 % to 13·9 %. A country's susceptibility profile was highly associated with vaccine coverage for the first dose. First dose coverage ranged from 91 to 97·5 % for low susceptibility countries, 75 to 85 % for intermediate susceptibility countries and 55 % for the high susceptibility country. Only the high susceptibility country still reports epidemic measles. In low susceptibility countries, which have achieved or are very close to measles elimination, the priority will be to maintain high MMR vaccine coverage in all geopolitical units for both vaccine doses. In moderate susceptibility countries there is still some endemic transmission, but also risk of outbreaks as pools of susceptibles accumulate. In the high susceptibility country the priority will be to increase infant vaccine coverage and reduce regional variation in coverage levels.

We conducted a seroepidemiological study to evaluate the potential impact of mass varicella vaccination on the transmission of varicella-zoster virus (VZV) in Italy, where vaccination is not mandatory. We tested 3179 serum samples, collected from September 1996 to October 1997, for specific anti-VZV antibodies using a commercially available ELISA. The results confirmed that varicella typically involves children (82·1% seroprevalence among 10- to 14-year-olds) and that the mean age of acquiring the infection seems to be increasing. The results also revealed that southern Italy, compared to the rest of the country, has a greater circulation of VZV and an earlier age of acquisition. The potential impact of mass vaccination among 12- to 18-month-old children on the epidemiological trend of the infection must be carefully considered, in that failure to reach high levels of coverage could lead to an increase in the mean age of acquisition, which is already occurring in Italy.

A cohort of 214 drug addicts with serum hepatitis and a cohort of 193 hepatitis patients without drug addiction were examined in respect of death rates, causes of death and a number of risk factors for reduced survival. The death rate was significantly higher among the drug addicts than among non-addicts. The annual mortality rate was 1·5% in the drug addict group and 0·7% in the non-addict group. The highest relative risk of death was 860 for female drug addicts in age group 15–24 compared to females of the same age in the general population. The most prevalent cause of death in the drug addict group was drug overdose (53%), whereas in the other group 66% died from various somatic diseases. Hepatitis or complications of viral hepatitis played no role as cause of death among the drug addicts, and infections as a whole were also responsible for very few deaths. For male drug addicts, imprisonment before admission and leaving hospital without the doctors' permission were risk factors for early death.

An outbreak of echovirus 11 infection was observed in a children's home that housed 16 children. Nine children younger than 1 year shared a large room on the first floor, which contained a large basin. Three of them presented with aseptic meningitis with CSF and stool samples positive for echovirus 11. The other six infants who shared the room were asymptomatic but their stools were positive for echovirus 11. Seven infants aged 1–2 years stayed on the second floor and were asymptomatic. One of them had positive stool culture for echovirus 11. No virus was isolated from stool samples taken from the 26 staff members. However, serology was suggestive for recent echovirus 11 infection in seven asymptomatic staff members. All seven worked either exclusively on the first floor or alternately on both floors. Our survey demonstrated that echovirus 11 may spread very efficiently in children's homes. The rate of meningitis in the infected infants was 30% while all the recently infected adults were asymptomatic.

The prevalence of blood-borne viruses in injecting drug users (IDUs) in Tayside, Scotland was determined by testing serum samples from IDUs who underwent attributable HIV antibody testing during 1993–7. The prevalence of antibodies to HIV was 29/802, (3·6%); to hepatitis C virus (HCV) 451/691, (65·3%); and to human T-cell leukaemia/lymphoma viruses type 1 and 2 (HTLV) 0/679, (0·0%). The prevalence of HIV and HCV antibodies were higher in subjects over the age of 25 (P=0·03 and P=0·001, respectively). During 1993–7 the prevalence of HCV fell only in younger female IDUs (P<0·01). HIV prevalence has declined dramatically since 1985, when a rate of 40% was recorded in similar populations. Harm reduction measures have failed to control HCV the spread of infection among IDUs in Tayside, as indicated by the high proportion of antibody positive IDUs, particularly males under the age of 25. Future studies should address the nature and effective reduction of continuing risk taking among IDUs in Tayside.

To predict which patients with current high-risk disease in the community may benefit most from additional preventive or therapeutic measures for influenza, we determined prognostic factors for influenza-associated hospitalization and death in a general practice-based case-control study among this segment of the vaccine target population with high influenza vaccination rates. In 103 general practices followed during the 1996/7 influenza epidemic, cases were either hospitalized or died due to influenza, bronchitis, pneumonia, diabetes, heart failure or myocardial infarction. Age- and gender-matched controls were randomly sampled from the remaining cohort. Information was collected by review of patient records. In total, 119 cases and 196 matched controls were included. Of the cases, 34, 25 and 4 % were hospitalized for acute pulmonary and cardiac disease and diabetes, respectively, and 37 % died. Multivariate conditional logistic regression analysis revealed that presence of chronic obstructive pulmonary disease, heart failure, previous hospitalization, high GP visiting rate and polypharmacy were independent prognostic factors. Several non-modifiable determinants can be used to ensure targeting additional preventive or therapeutic measures at the most vulnerable segment of the vaccine target group.

Enzyme immunoassay (EIA) was used to detect antibodies to Trichomonas vaginalis in sera from Zimbabwe. The EIA showed a sensitivity of 95 and 94% when compared with vaginal swab culture among women attending a family planning clinic (FPC) and female commercial sex workers (CSW) respectively. The specificity was 85 and 77% in the two groups. Culture-negative FPC women were sub-divided into high risk or low risk of exposure to trichomoniasis. The seroprevalence was 10% (6/61) among low risk women, 21% (10/48) among high risk women and 23% (9/39) among culture negative CSW. The EIA was positive in 46% (18/39) men with genital discharge but only 5% (2/37) healthy blood donors. None of 31 sera from prepubescent children was positive. The EIA may be useful for community surveys of trichomoniasis. Because T. vaginalis is a common sexually transmitted disease, the test may indicate behaviour that increases the risk of STD transmission.