In all temperate countries campylobacter infection in humans follows a striking seasonal pattern, but little attention has been given to exploring the epidemiological explanations. In order to better characterize the seasonal patterns, data from nine European countries and New Zealand have been examined. Several European countries with weekly data available showed remarkably consistent seasonal patterns from year to year, with peaks in week 22 in Wales, week 26 in Scotland, week 32 in Denmark, week 30 in Finland and week 33 in Sweden. In Europe, the seasonal peak was most prominent in Finland and least prominent in Scotland and Austria. In New Zealand the seasonality was less consistent since the peak was more prolonged. Possible explanations for the seasonal peaks are discussed. Research into the causes of campylobacter seasonality should help considerably in elucidating the sources of human infection.

To determine methicillin-resistant Staphylococcus aureus (MRSA) carriage in poultry and slaughterhouse personnel, 40 Dutch broiler flocks, in six slaughterhouses and 466 personnel were sampled. Of the employees, 26 were positive (5·6%), indicating a higher risk of exposure when compared to the general Dutch population (0·1%). This risk was significantly higher for personnel having contact with live animals (5·2%) – especially hanging broilers on the slaughterline (20·0%) – than for all other personnel (1·9%). Conventional electric stunning conferred a significantly higher risk of MRSA carriage for employees than CO2 stunning (9·7% vs. 2·0%). A total of 405 broilers were sampled upon their arrival at the slaughterhouse, of which 6·9% were positive. These broilers originated from 40 Dutch slaughter flocks of which 35·0% were positive. MRSA contamination in the different compartments of slaughterhouses increased during the production day, from 8% to 35%. Of the 119 MRSA isolates, predominantly livestock-associated MRSA ST398 was found, although 27·7% belonged to ST9 (spa type t1430). There is an increased risk of MRSA carriage in personnel working at broiler slaughterhouses, particularly those having contact with live animals.

Two independent studies were conducted to describe symptoms and potential risk factors associated with Blastocystis infection. Isolates were subtyped by molecular analysis. In the NORMAT study (126 individuals randomly sampled from the general population) 24 (19%) were positive for Blastocystis. Blastocystis was associated with irritable bowel syndrome (P=0·04), contact with pigs (P<0·01) and poultry (P=0·03). In the Follow-up (FU) study (follow-up of 92 Blastocystis-positive patients), reports on bloating were associated with subtype (ST) 2 (P<0·01), and blood in stool to mixed subtype infection (P=0·06). ST1 was more common in FU individuals (32%) than in NORMAT individuals (8%), whereas single subtype infections due to ST3 or ST4 were seen in 63% of the NORMAT cases and 28% of the FU cases. Only FU individuals hosted ST7, and ST6/7 infections due to ST7 or ST9 were characterized by multiple intestinal symptoms. The data indicate subtype-dependent differences in the clinical significance of Blastocystis.

Salmonella spp. comprise the second most common food-borne pathogens in the European Union (EU). The role of pigs as carriers of Salmonella has been intensively studied both on farm and at slaughter. Salmonella infection in pigs may cause fever, diarrhoea, prostration and mortality. However, most infected pigs remain healthy carriers, and those infected at the end of the fattening period could pose a threat to human health. Contamination of pig carcasses can occur on the slaughter line, and it is linked to cross-contamination from other carcasses and the presence of Salmonella in the environment. Therefore, Salmonella serovars present on pig carcasses can be different from those detected in the same bathes on the farm. In recent years, S. Typhimurium, S. Derby and S. serotype 4,[5],12:i:- (a monophasic variant of S. Typhimurium) have been the most common serovars to be detected in pigs in EU countries, but S. Rissen, S. Infantis, S. Enteritidis and S. Brandenburg have also been reported. In humans, several cases of salmonellosis have been linked to the consumption of raw or undercooked pork and pork products. Among the main serovars of porcine origin detected in confirmed human cases, S. Typhimurium, the monophasic variant S. 4,[5],12:i:- and S. Derby are certainly the most important.

This study describes the epidemiology and symptoms in 271 cryptosporidiosis patients in Stockholm County, Sweden. Species/genotypes were determined by polymerase chain reaction–restriction fragment-length polymorphism (PCR–RFLP) of the Cryptosporidium oocyst wall protein (COWP) and 18S rRNA genes. Species were C. parvum (n=111), C. hominis (n=65), C. meleagridis (n=11), C. felis (n=2), Cryptosporidium chipmunk genotype 1 (n=2), and a recently described species, C. viatorum (n=2). Analysis of the Gp60 gene revealed five C. hominis allele families (Ia, Ib, Id, Ie, If), and four C. parvum allele families (IIa, IIc, IId, IIe). Most C. parvum cases (51%) were infected in Sweden, as opposed to C. hominis cases (26%). Clinical manifestations differed slightly by species. Diarrhoea lasted longer in C. parvum cases compared to C. hominis and C. meleagridis cases. At follow-up 25–36 months after disease onset, 15% of the patients still reported intermittent diarrhoea. In four outbreaks and 13 family clusters, a single subtype was identified, indicating a common infection source, which emphasizes the value of genotyping for epidemiological investigations.

Monoclonal antibody–based competitive ELISA (C–ELISA) have been used for the specific measurement of antibodies to both rinderpest and peste des petits ruminants (PPR) viruses in cattle, sheep and goats. Examination of serum samples from sheep and goats in Gambia, before and after vaccination with rinderpest vaccine, suggested that antibodies to PPR virus could prevent an immune response to the rinderpest vaccine. Cattle sera from Nigeria and Ghana showed a high prevalence of antibody against PPR virus which may explain the difficulty experienced in some countries in achieving high post-vaccination immunity levels against rinderpest. Because antibodies against PPR virus are both cross–neutralizing and cross-protective against rinderpest virus further vaccination in the presence of antibodies against PPR virus may be a waste of national resources. This paper presents serological evidence for the transmission of PPR virus from sheep and goats to cattle and highlights the need to include PPR serology in the sero-monitoring programme to give a better indication of national herd immunity.

We estimated the true incidence of campylobacteriosis and salmonellosis in the European Union (EU) in 2009. The estimate was based on disease risks of returning Swedish travellers, averaged over the years 2005–2009, and anchored to a Dutch population-based study on incidence and aetiology of gastroenteritis. For the 27 EU member states the incidence of campylobacteriosis was about 9·2 (95% CI 2·8–23) million cases, while the incidence of salmonellosis was 6·2 (95% CI 1·0–19) million cases. Only 1/47 (95% CI 14–117) cases of campylobacteriosis and one 1/58 (95% CI 9–172) cases of salmonellosis were reported in the EU. The incidence rate of campylobacteriosis in EU member states varied between 30 and 13 500/100 000 population and was significantly correlated with the prevalence of Campylobacter spp. in broiler chickens. The incidence rate of salmonellosis in EU member states varied between 16 and 11 800/100 000 population and was significantly correlated with the prevalence of Salmonella Enteritidis in laying hens.

We estimated age-specific herpes zoster (HZ) incidence rates in the Kaiser Permanente Northwest Health Plan (KPNW) during 1997–2002 and tested for secular trends and differences between residents of two states with different varicella vaccine coverage rates. The cumulative proportions of 2-year-olds vaccinated increased from 35% in 1997 to 85% in 2002 in Oregon, and from 25% in 1997 to 82% in 2002 in Washington. Age-specific HZ incidence rates in KPNW during 1997–2002 were compared with published rates in the Harvard Community Health Plan (HCHP) during 1990–1992. The overall HZ incidence rate in KPNW during 1997–2002 (369/100000 person-years) was slightly higher than HCHP's 1990–1992 rate when adjusted for age differences. For children 0–14 years old, KPNW's rates (182 for females, 123 for males) were more than three times HCHP's rates (54 for females, 39 for males). This increase appears to be associated with increased exposure of children to oral corticosteroids. The percentage of KPNW children exposed to oral corticosteroids increased from 2·2% in 1991 to 3·6% in 2002. Oregon residents had slightly higher steroid exposure rates during 1997–2002 than Washington residents. There were significant increases in HZ incidence rates in Oregon and Washington during 1997–2002 among children aged 10–17 years, associated with increased exposure to oral steroids.

An outbreak of gastroenteritis occurred in Italy among 39 persons who had attended a private supper. All guests were previously healthy, young, non-pregnant adults; 18 (46%) had symptoms, mostly gastrointestinal (78%), with a short incubation period. Four were hospitalized with acute febrile gastroenteritis, two of whom had blood cultures positive for Listeria monocytogenes. No other microorganisms were recovered from the hospitalized patients' specimens. Epidemiological investigation identified rice salad as the most likely vehicle of the food-borne outbreak. L. monocytogenes was isolated from three leftover foods, the kitchen freezer and blender. Isolates from the patients, the foods and the freezer were indistinguishable: serotype l/2b, same phage type and multilocus enzyme electrophoretic type. Eight (36%) of 22 guests tested were found to have antibodies against L. monocytogenes, compared with none of 11 controls from the general population. This point source outbreak was probably caused by infection with L. monocytogenes. Unusual features included the high attack rate among immunocompetent adults and the predominance of gastrointestinal symptoms.

Haemophilus pertussis is a uniform species, without fixed varieties or “types.”

After isolation from the human subject it tends to pass through a series of antigenically distinct phases, of which the first two are toxic to guinea-pigs, whereas the last two are relatively harmless. The former probably correspond to the smooth, the latter to the rough phase of other bacteria.

The phase-changes are, up to a point, reversible.

Experiments on guinea-pigs have produced some evidence that the toxic Phase I is the best and perhaps the only antigen for the production of active immunity in guinea-pigs.

Five major human toxic syndromes caused by the consumption of shellfish contaminated by algal toxins are presented. The increased risks to humans of shellfish toxicity from the prevalence of harmful algal blooms (HABs) may be a consequence of large-scale ecological changes from anthropogenic activities, especially increased eutrophication, marine transport and aquaculture, and global climate change. Improvements in toxin detection methods and increased toxin surveillance programmes are positive developments in limiting human exposure to shellfish toxins.

Defining the causal relationship between a microbe and encephalitis is complex. Over 100 different infectious agents may cause encephalitis, often as one of the rarer manifestations of infection. The gold-standard techniques to detect causative infectious agents in encephalitis in life depend on the study of brain biopsy material; however, in most cases this is not possible. We present the UK perspective on aetiological case definitions for acute encephalitis and extend them to include immune-mediated causes. Expert opinion was primarily used and was supplemented by literature-based methods. Wide usage of these definitions will facilitate comparison between studies and result in a better understanding of the causes of this devastating condition. They provide a framework for regular review and updating as the knowledge base increases both clinically and through improvements in diagnostic methods. The importance of new and emerging pathogens as causes of encephalitis can be assessed against the principles laid out here.

In Canada, the number of human isolates of verotoxigenic (VT +ve) Escherichia coli 0157:H7 from diarrhoeal cases and haemolytic uraemic syndrome and haemorrhagic colitis has increased from 25 in 1982 to 2384 in 1989. A total of 3273 VT + ve E. coli 0157:H7 strains (3255 strains isolated in Canada and 18 isolates from other countries) were phage typed. The phage typing scheme has been extended from 14 to 62 phage types. Of these, five types occurred exclusively in other countries (type 47 in Japan; and types 49, 50, 51 and 52 in the U.K.). Thirty-five different phage types were identified in Canada; only nine of these (1, 2, 4, 8, 14, 21, 23, 31 and 32), each accounted for more than 1 % of the cases from human sources. The same nine types were the only ones observed among the isolates from non-human sources (meat and slaughter houses) suggesting a food-borne transmission in most of the human cases. Phage types 1 (30·5%); 4 (21%); 8 (13·5%); 31 (8·9%) and 14 (8%) were encountered in varying frequencies in most of the provinces; infrequently occurring phage types also showed regional variation. Thirteen different phage types were identified among 151 outbreaks representing 556 isolates of E. coli 0157:H7. More than one phage type were encountered in 12 outbreaks whereas in 141 outbreaks, all strains in each, had the same phage type.

Influenza virus elementary bodies can be disintegrated by treatment with ether with the liberation of two types of smaller particle, soluble antigen and red cell agglutinin.

Soluble antigen derived from the elementary body is identical in serological and chemical behaviour with soluble antigen recovered from infected tissues. Its chemical properties are those of a ribonucleoprotein.

The agglutinin is an enzyme, with a protein part carrying the enzymic activity and a combining group with affinity for red cells. The agglutinin does not react in complement-fixation tests by the short fixation technique, but by the use of prolonged fixation or by indirect complement fixation it can be shown to contain a strain specific antigen and also a non-specific antigen. The specific antigen is identical with the specific complement-fixing antigen demonstrable in the intact elementary body, and has combining affinity for red blood cells. The non-specific antigen is probably similar to the protein part of the soluble antigen. No evidence has been found that the agglutinin contains either carbohydrate or nucleic acid.

From the ether used to disintegrate the elementary body a serologically active lipid can be recovered which has properties suggesting that it is derived from the host cell.

The author is greatly indebted to Dr L. Dmochowski for assistance in experiments involving high-speed centrifugation, to Sir Macfarlane Burnet and Dr G. L. Ada for supplies of receptor-destroying enzyme, to Dr E. S. Duthie for crystalline trypsin and chymotrypsin, and to Dr R. R. Porter for a sample of crystalline ribonuclease.

The potential for hantaviral transmission among wild Norway rats by wounding associated with aggressive interactions was evaluated using a prospective sero-epidemiological study coupled with a mark-release-recapture survey. There was a significant association between an animal's serological status and the presence of wounds. Longitudinal studies of marked and released animals showed sero-conversion between captures was associated with wounding between captures more often (33%) than expected by chance, while unwounded animals seroconverted less often (8%) than expected. Typically, less than a 5% difference was found when comparing the incidence of seroconversion with the predicted rate based on wounding and seroprevalence. Infection was highly associated with the onset of sexual maturity and aggression but decoupled from rat age and the length of environmental exposure. Seroconversions occurred at times most associated with aggressive encounters and least associated with amicable behaviours that could lead to aerosol transmission.

Thirty-two different types of anaerobic bacteria isolated from chickens have been tested for anti-salmonella activity in vitro. Under the conditions of the test only Bacteroides hypermegas and a Bifidobacterium sp. were shown to inhibit the salmonellas and this was attributed to the production of volatile fatty acids (VFA's) coupled with a low pH. When these organisms were tested in newly hatched chicks no inhibition of s. typhimurium occurred. Possible explanations for this observation are considered.

The pH value and concentration of VFA's in the caecal material were determined in chicks from 0–84 days. In vitro tests with s. typhimurium indicated that, whilst the organism would be able to multiply at the pH and concentration of VFA's found during the first few days after hatching, the rapid increase inVFA concentration during the first 21 days would make this increasingly difficult. The significance of the developing caecal flora in relation to VFA production and pH is discussed.

Because certain feed additives are known to influence the carriage of salmonellas, the sensitivity of various caecal anaerobes to these compounds was determined in vitro, generally at 1, 10 and 100 μg/ml. The additives tested included flavomycin, furazolidone, nitrovin, tetracycline, tylosin, sulphaquinoxaline, virginiamycin and zinc bacitracin. All the organisms tested were inhibited by 100 μg/ml furazolidone; none were inhibited by 500 μg/ml sulphaquinoxaline.

Changes occurring in the VFA concentration, pH value and microflora of the caeca of chicks fed for 49 days or longer on a normal starter diet or the same diet containing 10 or 100 mg/kg nitrovin have been compared. When the chicks were fed on the diet containing 100 mg/kg nitrovin, the Gram-negative non-sporing anaerobes were eliminated as a significant part of the caecal flora. However, the VFA concentration combined with a low pH in chicks from 2 weeks onwards was still sufficient to inhibit salmonella multiplication. Other possibly interrelated factors which might lead to an increased salmonella carrier rate in the nitrovintreated chickens are discussed.

We report a retrospective analysis of 1933 Brucella strains isolated from humans and animals in Latin American countries between 1968 and 1991 and in Argentina between 1994 and 2006. During the first period 50% of strains were from humans, mainly from Argentina, Mexico and Peru but, while B. suis was the main cause of infection in Argentina, B. melitensis was responsible for most infections in the other countries. In Argentina in the later years, B. melitensis and B. suis were observed more frequently than in the first period while isolation of B. abortus decreased. Of 145 B. melitensis human isolates, eight gave susceptibility patterns to dyes and penicillin and two were B. melitensis biovar 3, which has never been reported in animals. Forty-six percent of B. suis isolated were resistant to dyes which is an atypical feature in this species.

A longitudinal observational study (18 months) was carried out in two Dutch dairy herds to explore clinical, epidemiological and molecular characteristics of Streptococcus uberis mastitis. Infections (n=84) were detected in 70 quarters of 46 cows. Bacterial isolates were characterized at strain level by random amplified polymorphic DNA (RAPD) fingerprinting. Persistent infections were usually attributable to one strain, while recurrent infections could be caused by different strains. When multiple quarters of a cow were infected, infections were mostly caused by one strain. In each herd, multiple strains were identified yet one strain predominated. The majority of all infections were subclinical, and infections attributed to predominant strains were more chronic than infections attributed to other strains. Epidemiological and molecular data suggest infection from environmental sources with a variety of S. uberis strains as well as within-cow and between-cow transmission of a limited number of S. uberis strains, with possible transfer of bacteria via the milking machine.

The coccidian protozoan parasite Cryptosporidium has been described in many host species since its discovery in the early part of the century, but it remained obscure until the recognition by veterinary workers in the 1970s of its importance as a cause of scours in young livestock animals [1–4].

Diphtheria is an uncommon disease in the UK due to an effective immunization programme; consequently when cases do arise, there can be delays in diagnosis and case-fatality rates remain high. We reviewed 102 patients with infections caused by toxigenic corynebacteria (an average of four per year) reported in the UK between 1986 and 2008: 42 Corynebacterium diphtheriae, 59 C. ulcerans and one C. pseudotuberculosis, as well as 23 asymptomatic carriers. Five fatalities were reported, all in unvaccinated patients. The major risk factor for C. diphtheriae infection continued to be travel to an endemic country. C. ulcerans infections became more common than C. diphtheriae infections in the UK; they were associated with contact with companion animals. The occurrence of indigenous severe C. ulcerans infections and imported C. diphtheriae cases highlights the need to maintain UK routine vaccination coverage at the 95% level in the UK, as recommended by the World Health Organization.