1. Requirements for a heat-stable smallpox vaccine are suggested.

2. Sheep lymph dried from the frozen state retains its potency at 22 and 37°C. better than aqueous, glycerinated or lanolinated suspensions of lymph. Dried crude lymph is not, however, sufficiently stable for use in tropical areas; it is also liable to vary in stability from batch to batch. No better results were obtained by prolonging secondary desiccation.

3. Phenol in low concentration is deleterious to vaccinia virus stored in the dried or liquid state at 22 and 37° C.

4. Dried vaccinia virus stored under nitrogen loses potency more rapidly than when sealed in vacuo, even when precautions are taken to rid the nitrogen of traces of oxygen and moisture.

5. A number of suspending media were examined for their preservative influence on purified vaccinia virus. None was effective in the liquid state, but all protected the virus against the lethal influence of freeze-drying. In the dried state, these media varied in their ability to protect the virus during storage at 22 or 37° C. The best results at both temperatures were obtained with virus freeze-dried in 5% peptone. This medium also protects the virus well at 45° C. Different types of peptone were equally effective.

6. Virus dried in 5% peptone still gave a full quota of successful primary vaccinations of children after storage for 12 months at 22° C., or for 4 months at 37° C.

7. Using partially purified sheep virus dried in 5% peptone, a vaccine can be produced which shows a high degree of resistance to heat, is relatively free from bacterial contamination, and is easy to reconstitute after prolonged storage. These results are highly reproducible.

Data from the national surveillance scheme for general outbreaks of intestinal disease, and the national laboratory reporting scheme were used to describe the epidemiology of small round structured virus (SRSV) infections in England and Wales. Between 1990 and 1995, there were 7492 laboratory reports of SRSV. Rates of reported illness were highest among infants, young children and the elderly. During 1992–5, some 707 SRSV outbreaks were reported. Outbreaks in hospital wards and residential facilities for the elderly accounted for 76% of the total, and annual numbers increased more than sixfold over the study period. There were wide regional variations in the numbers of SRSV outbreaks and laboratory reports. Both sporadic cases and outbreaks in the community are likely to be underestimated, but these passive surveillance systems provide an insight into the burden of SRSV infection among the institutionalized elderly.

To clarify whether prevalence or special pathogenicity is more important in determining urinary tract infection (UTI) causation, we compared the biotype, phylogenetic group, and virulence genes of Escherichia coli urine strains from 11 women with acute lower UTI with those of the host's dominant intestinal E. coli strain(s). Twenty-one unique E. coli clones were identified. For three women, the single faecal clone identified was also the host's urine clone, whereas for eight women faecal samples yielded 1 or 2 distinct non-urine clones (total, n=10), either with (n=3) or without (n=5) the concurrent urine clone. The eight urine clones from the latter eight women exhibited significantly greater inferred virulence, according to virulence gene content and phylogenetic background, than did the hosts' 10 corresponding ‘faecal only’ clones. In contrast, the three urine clones that were detected as the host's sole faecal clone exhibited significantly lower inferred virulence than the other eight urine clones, and were statistically indistinguishable from the 10 ‘faecal only’ clones. In conclusion, special pathogenicity is an important determinant of UTI pathogenesis in women, although prevalence may occasionally allow less virulent strains to cause UTI.

Blood samples were repeatedly collected from 12 sympatric woodland rodents over a 12-month period and DNA extracts from each were incorporated into a bartonella-specific PCR targeting a fragment of the 16S/23S rRNA intergenic spacer region (ISR). The composition of each amplicon was analysed using restriction enzyme analysis (REA) and base sequence comparison. Bartonella DNA was detected in 70 of 109 samples. Eleven samples contained DNA derived from more than one strain. Sequence analysis of 62 samples found 12 sequence variants (ISR genotypes) that were provisionally assigned to 5 different species, 2 of which were newly recognized. Up to five different species were detected in each animal. On about two-thirds of occasions, a species detected 1 month was not there the next, but never was a genotype superseded by another of the same species. However, a genotype could be re-encountered months later in the same animal, even if interim samples contained other genotypes. Our results suggest that although most animals are bacteraemic most of the time, specific infections are often superseded and that a complex and dynamic epidemiology of bartonella bacteraemias exists in woodland rodents.

A case-control study was conducted from 1 January to 31 May 2003 to identify risk factors for S. Heidelberg infection in Canada. Controls were pair-matched by age group and telephone exchange to 95 cases. Exposures in the 7 days before illness/interview were assessed using multivariate conditional logistic regression. Consumption of home-prepared chicken nuggets and/or strips [matched odds ratio (mOR) 4·0, 95% confidence interval (CI) 1·4–13·8], and undercooked eggs (mOR 7·5, 95% CI 1·5–75·5) increased the risk of illness. Exposure to a farm setting lowered the risk (mOR 0·22, 95% CI 0·03–1·00). The population-attributable fraction associated with chicken nuggets/strips was 34% and with undercooked eggs was 16%. One-third of study participants did not perceive, handle or prepare chicken nuggets and strips as high-risk products, although the majority of the products on the Canadian market are raw. These findings have prompted changes in product-labelling policy and consumer education.

During 1990 and 1991, dengue fever was detected in the State of Rio de Janeiro, Brazil. It occurred in two epidemic waves; one, from January to August 1990, caused predominantly by dengue virus type 1 (DEN-1) the other from October 1990 to May 1991 caused by type 2 virus (DEN-2). Dengue was confirmed by virus isolation and/or IgM capture enzyme-linked immunosorbent assay (MAC-ELISA) in 2109/5964 (35·4%) of the cases. DEN-2 virus was isolated from 180 patients. HAI tests indicated that of these previous infection with DEN-1 had occurred in 130 (72%). The epidemic was classified as dengue fever, but severe and even fatal cases occurred in association with secondary infection.

The preparation of a skin test antigen from Mycobacterium ulcerans by ultrasonic disintegration and filtration is described. The reagent, called Burulin, was tested in Africa in normal school children, and in patients with leprosy, tuberculosis or M. ulcerans disease. Those with tuberculosis or M. ulcerans disease were simultaneously tested with Tuberculin PPD. Burulin was found to be highly specific for patients in the reactive stage of M. ulcerans disease, and there was no cross-reaction in patients with other mycobacterioses. On the other hand, the majority of patients with M. ulcerans disease reacting to Burulin also produce positive reactions to Tuberculin PPD.

This study aimed to describe the transmission dynamics, the serological and virus excretion patterns of Nipah virus (NiV) in Pteropus vampyrus bats. Bats in captivity were sampled every 7–21 days over a 1-year period. The data revealed five NiV serological patterns categorized as high and low positives, waning, decreasing and increasing, and negative in these individuals. The findings strongly suggest that NiV circulates in wild bat populations and that antibody could be maintained for long periods. The study also found that pup and juvenile bats from seropositive dams tested seropositive, indicating that maternal antibodies against NiV are transmitted passively, and in this study population may last up to 14 months. NiV was isolated from the urine of one bat, and within a few weeks, two other seronegative bats seroconverted. Based on the temporal cluster of seroconversion, we strongly believe that the NiV isolated was recrudesced and then transmitted horizontally between bats during the study period.

A serosurvey of 349 military working horses and 231 military working dogs was conducted in ten sites in Morocco in 2012. This survey revealed a high level of exposure of these animals to flaviviruses: seroprevalence rates of 60% in horses and of 62% in dogs were observed using a competitive West Nile virus (WNV) enzyme-linked immunosorbent assay (cELISA). Seroneutralization test results showed that the majority of cELISA-positive results were due to exposure to WNV. Further assays conducted in vaccinated horses with a DIVA (Differentiating Infected from Vaccinated Animals) test indicated that anti-WNV antibodies had been stimulated through WNV natural infection. Moreover, in both species, seroneutralization tests suggested an exposure to Usutu virus (USUV). Data analysis did not show any significant difference of cELISA seropositivity risk between horses and dogs. Dogs may thus represent an interesting alternative to equines for the serological surveillance of WNV or USUV circulation, especially in areas where equine vaccination precludes passive surveillance (based on the detection of West Nile fever cases) in horses.

Fifty-four Rotterdam patients in which a primary infection with Campylobacter jejuni had been detected (index patients) were compared with 54 control subjects with regard to the consumption and preparation of foods 7 days before onset of illness and the keeping of pet animals. Significantly more index patients than controls had eaten chicken meat (47 v. 29; P = 0·0002), particularly at barbecues (14 v. 2; P = 0·0015). Marginally more index patients had eaten pork (47 v. 39; P = 0·048) or inadequately heated meat (13 v. 8), though in the last case numbers were too small to be statistically significant. The consumption of beef or mutton and outdoor eating (other than at barbecues) were essentially the same in both groups. There was no significant association with the keeping of pet animals, although a few more index patients had cage birds than controls (18 v. 12).

Twenty-one (15%) of 130 household contacts of index patients also suffered from diarrhoea during the same period. Circumstantial evidence pointed to a common source of infection with the index patient in 13 instances (nine households) and probable intrafamilial spread of infection in six instances.

Campylobacters were isolated from one of 110 swabs of kitchen work surfaces and eight of 107 swabs taken from lavatory bowls in index households.

To investigate the possible dependence on age of the rate of decline of IgG antibodies to pertussis toxin (IgG-PT) after natural infection with Bordetella pertussis we measured IgG-PT in follow-up sera of 121 patients (age 0–94 years) obtained after 123 episodes of B. pertussis infection. For analysis we applied a dynamic model for the inactivation of B. pertussis by the immune system. There were no significant differences in rise, peak and decline of IgG-PT between different age groups, although there was a tendency for a more rapid increase, a higher peak and a faster decline with increasing age. The IgG-PT cut-off of 100 U/ml for serodiagnosis of pertussis appeared valid in all age groups. A decline of IgG-PT to <10 U/ml was associated with increased risk of re-infection with B. pertussis.

This study reports on the clinical profiles of herpes simplex encephalitis (HSE) case-patients and the management of acyclovir prescriptions. We designed a study on the causes of encephalitis in France in 2007. Case-patients fulfilling the inclusion criteria were enrolled in all the hospitals that volunteered to participate. Fifty-five of 253 enrolled case-patients were diagnosed with HSE. Three (5%) HSE patients died and 48 (89%) were discharged with persistent neurological symptoms. All HSE patients were prescribed acyclovir, 10 of whom had a 2-week course; 42 a 3-week course; two received incomplete courses; and one received two courses of 21 days each due to relapse. The acyclovir dosage was reported for 45 adult HSE patients, 25 (53%) of whom received 10 mg/kg t.i.d. and 22 (47%) received 15 mg/kg t.i.d. The mortality rate was low despite 49% of patients being admitted to intensive-care units. A high dose of acyclovir was not associated with a better outcome in HSE patients. Most patients had persisting symptoms on discharge suggesting neuropsychological rehabilitation is an important issue for survivors.

No animals tested were positive for feline leukaemia virus antigen and Chlamydia psittaci antibodies, but all were positive for antibodies to feline calicivirus (FCV), feline herpesvirus 1 (FHV1) and rotavirus. They had antibodies to feline parvovirus (96%), feline coronavirus (84%) and cowpox virus (2%). Antibody to feline immunodeficiency virus (FIV) was found in 53% of animals, which were less likely to be infected with Haemobartonella felis, and had higher FHV antibody titres than cats without FIV. FCV was isolated from 51% cats and FHV1 and feline reovirus each from 4%. H. felis was present in 42% of animals, and antibody to Toxoplasma gondii in 62%. Clinical abnormality had a significant association with FIV and feline calicivirus infections, but sex, age, social status and feeding group had no significant association with prevalence of any parasites. Toxocara cati and Toxascaris leonina eggs were found, respectively, in 91% and 82% of animals tested.

This study was undertaken to survey the presence of Salmonella in 200 chicken samples collected from Mansoura, Egypt. Salmonella was detected in 16% (8/50), 28% (14/50), 32% (16/50) and 60% (30/50) of whole chicken carcasses, drumsticks, livers and gizzards, respectively, with an overall prevalence of 34% (68/200) among all samples. One hundred and sixty-six isolates were identified biochemically as Salmonella, and confirmed genetically by PCR, based on the presence of invA and stn genes. The spvC gene, however, was detected in only 25·3% (42/166) of the isolates. Isolates were serotyped as Salmonella Enteritidis (37·3%), S. Typhimurium (30·1%), S. Kentucky (10·8%), S. Muenster (8·4%), S. Virchow (4·8%), S. Anatum (4·8%), S. Haifa (1·2%), and four were non-typable. Antimicrobial susceptibility tests of the Salmonella isolates revealed that 100% were resistant to each of erythromycin, penicillin, and amoxicillin, while 98·8%, 96·4%, 95·2%, and 91·6% were resistant to nalidixic acid, sulphamethoxazole, oxytetracycline, and ampicillin, respectively. Multidrug resistance was evident for 92·8% of the isolates. The high contamination level of chicken meat with multidrug-resistant Salmonella can constitute a problem for public health.

Between March and May 1996 Stenotrophomonas maltophilia was cultured from endotracheal aspirate samples from five preterm infants in a neonatal intensive care unit (NICU). Four infants were superficially colonized, but a fifth died due to S. maltophilia septicaemia. S. maltophilia was cultured from tap water from three outlets in the NICU including one with a previously unnoticed defective sink drain. Water from these outlets was used to wash the preterm infants. Environmental and clinical S. maltophilia isolates yielded identical banding patterns on random arbitrary polymorphic DNA (RAPD) PCR analysis. The outbreak was controlled by reinforcement of hand disinfection, limitation of the use of tap water for hand washing and by using sterile water to wash the preterm infants. We conclude that tap water should not be used for washing preterm infants in the NICU, unless steps are taken to prevent microbial growth in the outlets.

The aim of this study was to establish the relative importance of various risk factors for toxoplasmosis in a United Kingdom antenatal population. Toxoplasma immune status was determined by an immunoassay and linked to a questionnaire exploring dietary and environmental exposure to toxoplasmosis. The overall seroprevalence found was 9·1% (172/1897). A significantly higher seroprevalence was associated with rural location of the childhood home, childhood home in Europe excluding the United Kingdom, feeding a dog raw meat and increased age. A non-significant higher prevalence of toxoplasmosis was observed in women who had lived with a cat or kitten as a child. In contrast to recent European studies only weak associations between diet and toxoplasmosis were found. Gardening activity was not associated with seropositivity but a non-significant lower seroprevalence was seen in gardeners who always wore gloves. This study confirms that toxoplasma prevalence in the United Kingdom has continued to decline since the 1960s. The increasing seroprevalence with age found in this study, highlights the continuing need to educate women of childbearing age about the risk factors for toxoplasmosis.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65·7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.

This study aimed to disentangle the independent contributions of Helicobacter pylori infections in mothers, fathers and siblings to the risk for the infection in the 11–13 years age group. Index children from a cross-sectional Stockholm school survey and their family members completed questionnaires and contributed blood samples. H. pylori serostatus was determined with an enzyme-linked immunosorbent assay and immunoblot. Fifty-four seropositive and 108 seronegative index children were included and 480 out of 548 family members contributed blood. In multivariate logistic regression modelling, having an infected mother (OR 11·6, 95% CI 2·0–67·9) or at least one infected sibling (OR 8·1, 95% CI 1·8–37·3) were risk factors for index child infection, whilst the influence of infected fathers was non-significant. Birth in high-prevalence countries was an independent risk factor (OR 10·4, 95% CI 3·4–31·3). H. pylori infections in mothers and siblings and birth in high-prevalence countries stand out as strong markers of infection risk amongst children in Sweden.

In order to evaluate the incidence and risk factors of infection by hepatitis C virus (HCV) among injecting drug users (IDUs), we conducted a prospective cohort study of HCV- and human immunodeficiency virus (HIV)-negative IDUs in the North and East of France. A total of 231 HCV and HIV IDUs who had injected drugs at least once in their lifetime were followed up every 3 months over a 12-month period. Serum anti-HCV and anti-HIV were tested at inclusion in the study and at the end of the follow-up. Data on injecting practices were collected at inclusion and at each visit. Of the 231 participants included, 165 (71·4%) underwent a final HCV and HIV serum test. The incidence was nil for HIV infection and 9/100 person-years (95% CI 4·6–13·4) for HCV infection. In a multivariable analysis, we found that syringe and cotton sharing were the only independent predictive factors of HCV seroconversion.

This study reports the epidemiology of respiratory syncytial virus (RSV) in hospitalized children in Cyprus over three successive seasons (2010–2013) and the association between prevalent genotypes and disease severity. RSV infections had a circulation pattern from December to March. Most RSV-positive children (83%) were aged <2 years. Genotyping of RSV isolates showed that during the first winter season of the study (2010–2011), the only RSV genotype circulating was GA2 (RSV-A), followed by genotype BA (RSV-B) in the next winter season with only few sporadic cases of GA2. During the last winter season of the study (2012–2013) the newly emerged RSV genotype ON1 (RSV-A) was virtually the only circulating genotype. Children infected with genotype ON1 suffered a significantly milder illness compared to infections with genotypes GA2 and BA with a higher percentage of BA-infected children requiring oxygen. Our findings are in contrast to the majority of published reports that suggest RSV-A causes more severe illness than RSV-B. Therefore, further investigation of the association between RSV genotypes and disease severity is required, as it might affect treatment strategies in the future.