HIV-infected individuals with high levels of IgG antibodies against human herpesvirus-8 (HHV-8) are at increased risk of developing Kaposi's sarcoma. The aim of this study was to measure the association between HHV-8 viraemia and IgG antibody responses (by immunofluorescence) in a group of 201 HIV-infected individuals attending outpatient clinics, 91 in-patients with AIDS and 87 HIV-infected patients admitted with Kaposi's sarcoma. Compared to HIV-infected outpatients, the adjusted odds ratio in relation to Kaposi's sarcoma was 15·4 (95% CI 4·4–54·2) in those with viraemia, 25·1 (95% CI 6·6–95·6) in those with a positive immunofluorescent signal and ∞ (lower exact CI 33·6) in those with a high immunofluorescent signal (all P trend <0·001). Among those without HHV-8 viraemia, 23% were IgG-positive, but only 5·5% had a high immunofluorescent signal. In those who were viraemic, 89·1% were IgG-positive, and 28·2% had a high immunofluorescent signal, suggesting viraemia is associated with high HHV-8 immunofluorescence IgG signal.

Clinical descriptions of Epstein–Barr virus (EBV) positive infectious mononucleosis (IM) are rare and their results are inconsistent. Over a 4-year period, we prospectively studied 590 young adults with clinically suspected IM, all of whom were tested for the presence of EBV IgM antibodies. We investigated the demographical, clinical and laboratory features of subjects with positive EBV IgM serology and heterophile antibodies. Contrary to previous studies, we found a seasonal disease pattern with a peak incidence during summer months, and a lower-than-expected prevalence of lymphadenopathy (88·9%), leucocytosis (46·2%), atypical lymphocytosis (89·2%) and elevated liver enzymes (57·9%). The prevalence of hyperbilirubinemia was relatively high (14·9%). The classic triad of fever, sore throat and lymph-adenopathy had relatively low sensitivity (68·2%) and specificity (41·9%) for EBV infection. Our study provides a complete and updated description of the clinical and laboratory presentation of laboratory confirmed IM, which is important for both clinicians and epidemiologists.

Evidence from epidemiological and molecular studies of bovine Escherichia coli O157[ratio ]H7 suggests that strains are frequently transmitted across wide geographic distances. To test this hypothesis, we compared the geographic and genetic distance of a set of international bovine Escherichia coli O157[ratio ]H7 isolates using the Mantel correlation. For a measure of genetic relatedness, pulsed-field gel electrophoresis of six different restriction enzyme digests was used to generate an average Dice similarity coefficient for each isolate pair. Geographic distance was calculated using latitude and longitude data for isolate source locations. The Mantel correlation between genetic similarity and the logarithm of geographic distance in kilometers was −0·21 (P<0·001). The low magnitude of the Mantel correlation indicates that transmission over long distances is common. The occurrence of isolates from different continents on the same cluster of the dendrogram also supports the idea that Escherichia coli O157[ratio ]H7 strains can be transferred with considerable frequency over global distances.

Cryptosporidium oocysts are commonly detected in surface-derived drinking water. However, the public health significance of these findings is unclear. This study compared serological responses to two Cryptosporidium antigen groups for blood donors and college students using chlorinated and filtered river water vs. ground-water sources. The surface water received agricultural and domestic sewage discharges upstream. Participants from the surface-water city had a higher relative prevalence (RP) of a serological response to the 15/17-kDa antigen group (72·3 vs. 52·4%, RP=1·36, P<0·001) and to the 27-kDa antigen group (82·6 vs. 72·5%, RP=1·14, P<0·02). Multivariate logistic regression analysis found that the people with a shorter duration of residence or drinking bottled water also had a lower seropositivity for each marker. Use of private wells was associated with a higher prevalence of response to the 15/17-kDa markers. Seroconversion to the 15/17-kDa antigen group was more common in the residents of the city using surface water. These findings are consistent with an increased risk of Cryptosporidium infection for users of surface-derived drinking water compared with users of municipal ground-water-derived drinking water. Users of private well water may also have an increased risk of infections.

Six countries (Denmark, England and Wales, France, Germany, Italy and the Netherlands) conducted large serological surveys for mumps, in the mid-1990s, as part of the European Sero-Epidemiology Network (ESEN). The assay results were standardized and related to the schedules and coverage of the immunization programmes and the reported incidence of mumps. Low incidence of disease and few susceptibles amongst adolescents and young adults was observed in countries with high mumps vaccine coverage (e.g. the Netherlands). High disease incidence and large proportions of mumps virus antibody negative samples in adolescent and young adult age groups was noted in countries with poor vaccine coverage (e.g. Italy). The build-up of susceptibles in older children and adolescents in England and Wales, France, the former West Germany and Italy indicate the possibility of further mumps outbreaks in secondary school environments. To control mumps in western Europe, current MMR immunization programmes will need to be strengthened in a number of countries. Sero-surveillance of mumps is an important component of disease control and its usefulness will be enhanced by the development of an international mumps standard.

Acarological risk was calculated as the probability of encountering at least one host-seeking Ixodes ricinus tick infected by the pathogen Borrelia burgdorferi sensu lato, in 100 m transects in the province of Genoa, Italy. The seasonal pattern of I. ricinus was studied using generalized estimating equations (GEE) with negative binomial error, to consider overdispersion of tick counts and repeated sampling of the same dragging sites from April 1998 to March 1999. Prevalence of infection by B. burgdorferi s.l. was evaluated by PCR and hybridization with genospecies-specific probes. Acarological risk (R) peaked in April (R=0·2, 95% CI 0·13–0·26) and November (R=0·29, 95% CI 0·10–0·46). Borrelia garinii and B. valaisiana were the most common genospecies at our study site suggesting a major role of birds as reservoirs. DNA from Anaplasma phagocytophilum, the agent of granulocytic ehrlichiosis in humans and animals, was amplified from an adult I. ricinus.

The study investigated the transfer and the stability of the S. intermedius flora in three bitches and their puppies. A total of 240 cutaneous and mucosal isolates of S. intermedius was collected from three healthy Cavalier King Charles spaniels and their puppies during the immediate prepartum period and after whelping, over a total of 15 weeks. The isolates were genotyped with random amplified polymeric DNA-polymerase chain reaction analysis (RAPD-PCR) using two primers. Seventeen different genotypes of S. intermedius were identified. One or two of the genotypes were dominant in each of the bitches and their puppies. The rest were isolated only once or twice from the bitches or their puppies. The study indicates that S. intermedius flora within each studied bitch mainly consisted of one or two dominating and persistent clones, which were transferred from the dam to her puppies immediately after birth.

To obtain insight into mumps immunity 9 years after introduction of vaccination in The Netherlands, antibodies were measured in a national sample (n=8298) and in clustered religious groups with low vaccine acceptance (n=254). All sera were tested by indirect ELISA, and agreement with neutralization assay was assessed in a subsample (n=623). Overall seroprevalence in the adult age groups in the national sample was 96·2% (95% confidence interval 95·4–97·0%). Seroprevalence was somewhat lower in the vaccinated age groups, but still sufficient to maintain herd immunity. After the first dose of vaccine, an increase up to age three years to 93·2% (89·8–96·6%) and a subsequent decline in prevalence to 88·9% (81·7–96·0%) at age 7 years was seen. Seroprevalence in those eligible for two vaccinations was 94·4% (91·3–97·4%). In the religious groups, seroprevalence was generally lower in the age group 1–4 years (30% (18–95%)) than in the national sample, but similar in the older age groups. Seroprevalence as estimated by neutralization assay was only slightly lower for all age groups [ges ]1 year. Therefore, the indirect ELISA is a reliable method for measuring mumps virus-specific antibodies in population-based studies. However, to allow for inter-laboratory comparison, international unitage should be developed.

A cross-sectional study was conducted in Mapastepec, a rural community of the southern state of Chiapas, Mexico. The overall prevalence of leptospirosis infection in 1169 subjects was 37·7% [95% confidence intervals (95% CI) 34·9–40·5]. The main risk factors related to leptospirosis infection were flooding, mainly if subjects had a skin cut or abrasion [odds ratio (OR) 4·2; 95% CI 3·1–5·7], having domestic animals, either dogs and/or cats (OR 1·3; 95% CI 0·96–1·8) or cattle and/or pigs (OR 1·9; 95% CI 1·3–2·7), contact with animal excreta with no protection and with a skin cut or abrasion (OR 2·3; 95% CI 1·1–4·6). Those subjects with a dengue infection in the previous year had also an excess risk (OR 1·4; 95% CI 0·9–2·0). Mapastepec is a previously unknown area with high endemicity. Specific preventive measures should be adopted to prevent any contact with infected animals, and animal immunization should also be implemented. There is need of an epidemiological surveillance system to allow proper diagnosis.

Pulsed field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) methods were applied for molecular typing of 130 Mannheimia (Pasteurella) haemolytica serotype A1 isolates obtained from 13 prefectures in Japan. These isolates were divided into 15 ApaI PFGE profiles that formed six distinct clusters (clusters A–F). Fifty-three (40·7%) isolates were classified in cluster B, and 20·0, 13·8, 12·3, 6·9 and 6·1% of isolates were in clusters E, A, F, D and C, respectively. The isolates of cluster B were differentiated into seven subtypes (B1–B7) and subtype B5 contained 63% (34/53) of isolates. RAPD revealed four banding patterns (types I–IV), and among 130 isolates 60·7% (79/130) of isolates were RAPD type I. All of the RAPD type I isolates were grouped into clusters A–C by PFGE. There was no relationship between molecular typing and geographic origin of these isolates. These results indicate that isolates of M. haemolytica A1 strain with various molecular profiles have already spread in Japan and may have caused sporadic infections.

Acute flaccid paralysis (AFP) surveillance data from India were analysed to examine sensitivity of poliovirus isolation from stool specimens and the added sensitivity obtained from collection of a second stool specimen. Analysis was restricted to Indian AFP cases, 1998–2000, with two adequate stool specimens. The proportion of cases confirmed with wild poliovirus isolation by the second specimen only was calculated, regardless of specimen quality. Overall specimen sensitivity (1998–2000) was 81% using the first specimen, 78% using the second, and 96% using both. Sensitivity increased from 1998 to 2000, with slightly higher sensitivity each year for the first specimen. The second specimen increased sensitivity by 15% overall and contributed more when the first specimen was collected late or was in poor condition. As wild poliovirus disappears, increased sensitivity provided by a second stool specimen may reduce the risk of missing circulating virus.

The aim of this study was to identify the high-risk factors associated with the development of ocular lesions in a large cohort of children with congenital toxoplasmosis (CT), irrespective of their gestational age at the time of maternal infection. Children were managed according to a standardized protocol and monitored for up to 14 years at the Croix-Rousse Hospital, Lyon, France. Cox model and a flexible regression, spline-based method were used for the analysis. During a median follow-up time of 6 years, 79 of the 327 children (24%) had at least one retinochoroidal lesion. No bilateral impairment of visual acuity was observed. The risk of a child developing ocular disease was higher not only when mothers were infected early during pregnancy, which was expected, but also when CT was diagnosed prior to or at the time of birth, when non-ocular manifestations were present at baseline and when birth was premature.

Rotaviral associated disease of infants in the UK is seasonal and infection in adults not uncommon but the relationship between these has been little explored. Adult sera collected monthly for one year from routine hospital samples were screened for the presence of anti-group A rotavirus immunoglobulin M class antibodies as a marker of recent infection. Anti-rotavirus IgM was seen in all age groups throughout the year with little obvious seasonal variation in the distribution of antibody levels. IgM concentrations and the proportion seropositive above a threshold both increased with age with high concentrations consistently observed in the elderly. Results suggest either high infection rates of rotavirus in adults, irrespective of seasonal disease incidence in infants, IgM persistence or IgM cross-reactivity. These results support recent evidence of differences between infant and adult rotavirus epidemiology and highlight the need for more extensive surveys to investigate age and time related infection and transmission of rotavirus.

Two forms of Corynebacterium pseudotuberculosis infection in Israeli dairy cattle herds during a survey period of 13 years (1989–2001) are described. The more common form, which was diagnosed in 45 herds, was characterized by ulcerative granulomatous lesions which occurred either sporadically – in 26 herds (with a morbidity rate of up to 5% – or in an epidemic course in 19 herds. Most (80·6%) of the affected animals were cows; the rest were first-calving cows (16·2%) and heifers (3·2%). The morbidity occurred mostly during the summer months. The ulcerative granulomatous lesions appeared in three clinical forms: cutaneous, mastitic and visceral. Mixed forms were also observed. The morbidity rate was 6·4% and the culling rate reached 16·3% of the affected animals. Most of the strains of C. pseudotuberculosis which were isolated from the abscesses in the cutaneous form of the disease and from milk samples failed to reduce nitrate. A decrease in milk production (6%) and an increase in bulk-milk somatic cell count were noted. Necrotic and ulcerative dermatitis on the heel of the foot occurred in an epidemic course in heifers in only two herds during the winter months, with morbidity rates of 7·5 and 76·2%, respectively. C. pseudotuberculosis isolates from skin lesions and from the soil did reduce nitrate. Clinical, epizootiological and microbiological aspects of the infection are described.

An outbreak of gastroenteritis affected a school attended by children aged 4–11 years. Epidemiological features suggested this was due to Norwalk-like virus (NLV) and this was confirmed by polymerase chain reaction (PCR). Nucleotide sequence analysis of the PCR amplicons revealed identical strains in all five positive stool samples. Pupils were significantly more likely to become ill following an episode of vomiting within their classroom (adjusted odds ratio 4·1, 95% CI 1·8–9·3). The times from exposure to illness were consistent with direct infection from aerosolized viral particles where exposure to vomiting was high.

Cleaning with quaternary ammonium preparations made no impact on the course of the outbreak. However, the outbreak stopped after the school closed for 4 days and was cleaned using chlorine-based agents. This study confirms the importance of vomiting in the transmission of NLV and provides evidence that direct infection with aerosolized viral particles occurs.

From April 1998 to March 2000, 18 broiler flocks were followed from the hatchery to the slaughterhouse. Campylobacter was not found in the hatchery, 1-day-old chicks or in the rearing house before the arrival of the chicks. The infection of broiler flocks increased continuously during the rearing time, with a total of seven positive flocks at the end of rearing. Farms with Campylobacter-positive broilers were characterized by the circulation of Campylobacter in the environment (puddles, dung hill) and on the footwear of the farmer. The administration of antibiotics did not significantly reduce Campylobacter shedding. With the exception of one flock during rearing and a few flocks in the slaughterhouse with a mixed Campylobacter coli–Campylobacter jejuni infection, C. jejuni exclusively was found both during rearing and on the carcasses. A significant correlation exits between the contamination of the broilers during rearing and the carcasses after processing. No slaughterhouse was able to avoid contamination of carcasses when status-positive animals were delivered. Moreover, six negatively delivered flocks yielded positive carcasses, the result of a supplementary contamination, which occurred during transport and slaughtering.

In simple epidemiological models that describe the interaction between hosts with their parasites, the infection process is commonly assumed to be governed by the law of mass action, i.e. it is assumed that the infection rate depends linearly on the densities of the host and the parasite. The mass-action assumption, however, can be problematic if certain aspects of the host–parasite interaction are very pronounced, such as spatial compartmentalization, host immunity which may protect from infection with low doses, or host heterogeneity with regard to susceptibility to infection. As deviations from a mass-action infection rate have consequences for the dynamics of the host–parasite system, it is important to test for the appropriateness of the mass-action assumption in a given host–parasite system. In this paper, we examine the relationship between the infection rate and the parasite inoculum for the water flee Daphnia magna and its bacterial parasite Pasteuria ramosa. We measured the fraction of infected hosts after exposure to 14 different doses of the parasite. We find that the observed relationship between the fraction of infected hosts and the parasite dose is largely consistent with an infection process governed by the mass-action principle. However, we have evidence for a subtle but significant deviation from a simple mass-action infection model, which can be explained either by some antagonistic effects of the parasite spores during the infection process, or by heterogeneity in the hosts' susceptibility with regard to infection.

Brachyspira (B.) pilosicoli, the causative agent of intestinal spirochaetosis in pigs, is a quite common laboratory finding from faecal samples of weaned and growing pigs in Finland. A better understanding of the epidemiology of B. pilosicoli in and between Finnish pig farms is needed. Altogether 131 B. pilosicoli isolates from 49 Finnish sow herds were studied by pulsed-field gel electrophoresis. MluI was used as a restriction enzyme for all the isolates, and SmaI for 70 isolates. The isolates were divided into 54 different macrorestriction profiles (MRP) by MluI. Most farms had distinct B. pilosicoli genotypes, and common genotypes among herds were rare. B. pilosicoli was re-isolated after 3 years in three herds; the same MRP persisted in each of these herds. A genetic clustering of B. pilosicoli isolates between two major pork production areas was not detected.

Campylobacter isolates from raw retail chickens (n=434) sampled between 1998 and 2000 were tested for resistance to 12 antibiotics. Among 208 campylobacters tested, more than 90% of isolates were susceptible to 4 out of 9 antibiotics (nalidixic acid, erythromycin, chloramphenicol and gentamicin). Most campylobacters were resistant to 3 antibiotics and multiple resistance was found in 4%. Ciprofloxacin resistance was 11%. Campylobacter contamination (28%) in imported chickens (n=150) was almost half that found in local whole chickens (50%), but the resistance of imported isolates (n=42) was similar to that of local campylobacters. Resistance in isolates from imported chicken breasts was generally more common, but to only 4 antibiotics. Resistance patterns of chicken isolates were compared to human clinical isolates (n=494), and a greater similarity was found between the clinical and local isolates than with imported campylobacters. Lower chloramphenicol resistance was found in clinical Campylobacter isolates than in those from chicken sources.

An outbreak of gastroenteritis due to Norwalk-like virus (NLV) affecting approximately 500 people occurred in a Swedish ski resort during February–March 2002. Epidemiological investigations were performed on cohorts of schoolchildren, permanent residents and skiers visiting the area. Attack rates were respectively 39·7, 29·9 and 38·5%. Drinking un-boiled water originating from one of the three communal water systems was a significant risk factor for all groups. For schoolchildren, the risk of illness increased with increasing amount of water consumed. Nine of 12 stool samples of patients analysed tested positive for NLV. The water tested negative for indicator bacteria and results of NLV tests were inconclusive. In the absence of microbiological findings, the environmental authorities were reluctant to act based on the epidemiological analysis alone, and intervention was delayed until mid-April, following the discovery of a crack in a sewage pipe 10 m from the well.