Woodhouse's experiments on the carcinogenicity of ten different fractions for the skin of mice have been analysed statistically. Two experiments separated by a considerable period of time were performed on each fraction.

A number of different measures of carcinogenicity were used. All agree in showing that

(1) The apparent carcinogenicity was greater in the 2nd series of experiments.

(2) There were significant differences in carcinogenicity. The fractions can be divided into three groups within which the carcinogenicities were about the same, viz. F H I K, B D G L E, M.

Cattle and sheep were housed with infected pigs for 11 days. Small amounts of virus were recovered intermittently from the pharynx, milk and rectal swabs of the cattle, but no evidence of subclinical infection was found. Some indication of virus growth in the sheep was obtained in that large amounts of virus were recovered from the pharyngeal region 4 to 7 days after exposure and six of the eight sheep developed significant titres of neutralizing antibody which were maintained in four animals for at least 6 weeks.

We compared rotavirus detection patterns before (2001–2006) and after (2008–2015) rotavirus vaccine introduction. We also compared rotavirus detection patterns in odd (2009, 2011, 2013, 2015) and even (2008, 2010, 2012, 2014) years post-vaccine separately. Results of stool rotavirus antigen testing from inpatient, outpatient and emergency department encounters from July 2000 to July 2015 at two paediatric hospital laboratories in Atlanta, Georgia were reviewed. Post-vaccine, rotavirus detection declined (30.2% vs. 13.7% (overall 54.6% decline, P <0.001)), occurred more frequently outside the rotavirus season (19.8% vs. 3.5%; P < 0.001), and was more common among older children (26 vs. 13 median months of age; P < 0.001). During odd years post-vaccine, rotavirus detection was significantly higher than even years (20.2% vs. 6.4%; P < 0.001). Rotavirus detection declined substantially and developed a biennial pattern in the post-vaccine era. The intensity and temporality of rotavirus detection in odd years post-vaccine resembled that observed pre-vaccine, although considerably reduced in magnitude.

Six hundred and fifty-seven children aged between 0 and 12 months were randomly chosen and studied for measles antibody titres by the haemagglutination inhibition (HAI) test. The results showed significant variations in HAI antibody titres. Children between 0–3 months showed high measles HAI antibody titres which declined to a trough between 4 and 0 months. A rise in HAI antibody titre was observed from 10 to 12 months age. Multiparity and higher age in the mothers were noted as probable factors influencing the titres of measles HAI antibody in children. The results indicated that with increased maternal parity, measles HAI antibody titres in the children declined.

A total of 574 samples, of seven different types, were examined for the presence of salmonellas. All the specimens were pre-enriched in buffered peptone water and enriched in Rappaport–Vassiliadis medium (RV medium). In one trial 0·1 ml of pre-enrichment culture of 497 samples (79 chicken carcasses, 228 specimens of minced meat, 100 pork sausages, 19 samples of dried powdered chicken meat, 11 specimens of faeces of healthy pigs and 60 samples of sewage polluted natural sea water) was seeded to 10 ml as well as to 100 ml of RV medium. With the first inoculum (ratio 0·1:10), 111 samples were found to contain salmonellas, while with the second inoculum (ratio 0·1:100), only 102 positive samples were detected. This difference is marginally significant (P < 0·05). In another trial, 0·1 ml, 0·2 ml and 0·5 ml of pre-enrichment culture of 162 specimens (71 chicken carcasses, 40 samples of sewage polluted sea water and 51 samples of sewage polluted river water) were in turn introduced to 10 ml of RV medium. With the 0·1 ml inoculum 93 positive samples were detected, while with the 0·2 and 0·5 ml inocula 93 and 88 positive samples were found. The differences are not statistically significant. In these trials the growth of competing organisms was minimal with ratios of inocula 0·1:10 or 0·1:100.

Tuberculosis (TB) is a common infectious disease, and the present study aims to explore the associations of single nucleotide polymorphisms (SNPs) at rs1135216 and rs1057141 of transporter-associated antigen processing (TAP1) and rs2228396 of TAP2 with pulmonary tuberculosis (PTB) risk. A case–control study including 168 smear-positive PTB cases and 251 controls was conducted. Genotyping of the SNPs at rs1135216, rs1057141 and rs2228396 was performed, and their associations with PTB risk were analysed with SPSS software version 19.0. After conducting stratification for age, a significant association was detected for rs1057141 with increased PTB risk (OR = 0.17, 95% CI 0.04–0.79) among those aged ≥60 years. For those aged <60 years, a marginally significant association was detected between rs1135216 TC/CC and PTB risk (OR = 1.97, 95% CI 0.93–4.19). Haplotype analysis revealed that the haplotype AT at rs1135216 and rs2228396, as well as AAT at rs1057141, rs1135216 and rs2228396, was associated with increased PTB risk, and the ORs were 2.83 (95% CI 1.30–6.14) and 2.89 (95% CI 1.34–6.27), respectively. Rs1057141 is a genetic predictor of reduced PTB risk for those aged ≥60 years, while rs1135216 might be a potential genetic predictor for those aged <60 years. Haplotype AT at rs1135216 and rs2228396, as well as AAT at rs1057141, rs1135216 and rs2228396, is a genetic marker that may predict PTB risk.

We investigated the presence of Mycobacterium spp. in livestock in northern China. Of the 163 clinical samples selected for this study, 20 were from throat swabs of dairy cows, and 143 were tissue samples (including lung tissue from one reindeer, hilar lymph node tissue from 55 cows, and liver tissue from 87 sheep). A total of 41 mycobacterial isolates were identified including two isolates of M. caprae and 39 non-tuberculous mycobacteria (NTM) isolates. Multi-locus variable-number tandem repeat analysis (MLVA) profiles of the two M. caprae isolates proved to be unique. This is the first report of M. caprae isolates from livestock in China. This study also confirms previous reports that NTM is common in livestock in northern China.

Group-A streptococci belonging to opacity-factor (OF)-positive M types were poorly haemolytic on horse-blood agar, but members of OF-negative M types, and M-negative variants of OF-positive strains gave good haemolysis. Horse-serum extracts of strains of OF-negative serotypes 6 and 12, and M-negative variant cultures of OF-positive serotypes 4 and 49, had higher titres of streptolysin S than did similar extracts of OF-positive, M-positive cultures of types 4 and 49. However, much larger amounts of streptolysin S could be extracted with ribonuclease (RNAase)-digested yeast ribonucleic acid (RNA) and M-positive OF-positive cultures treated in this way gave extracts at least as strong as did their M-negative variants or the OF-negative strains. Extraction of streptolysin S from OF-negative strains by serum could be inhibited by previous incubation of the serum with extracellular OF, suggesting that the production of diffusable OF by M-positive variants of OF-positive serotypes interferes with the extraction of streptolysin S by serum and leads to poor haemolysis on blood agar.

The haemolysis of all strains on blood agar was greatly improved by the incorporation of 0·1% (w/v) RNAase-digested yeast RNA into the medium, but the improvement was most marked in OF-positive serotypes.

Two isolations of Arizona from humans were made in Sheffield in 1966. The first was from a 3-year-old girl with a history of gastro-enteritis; the second was from her 5-year-old brother who was a symptomless excretor. Infection was traced to pet terrapins recently purchased from a local pet shop. The relative epidemiological significance of Arizona infection and the potential hazard of pet terrapins has been reviewed.

We wish to thank Dr V. G. S. Damms for his help and co-operation and for allowing us to publish details of his patients, Dr J. G. Wallace for his work on the preliminary identification of the organism, and Dr Joan Taylor and Dr E. H. Gillespie for their helpful advice and criticism.

One thousand pharyngeal swab specimens were processed for aerobic culture to determine the carriage rate of Gram-negative bacilli (GNB). The isolates were identified and their sensitivity determined to 11 antibacterial drugs following standard techniques.

Similar pharyngeal carriage rates of GNB were found among the various groups of healthy subjects. Patients had higher colonization rates (27%) than healthy subjects (16%). The increase in prevalence of GNB seemed to be associated with underlying diseases and duration of hospitalization.

Klebsiella (36%) was the most frequent genus amongst the 215 isolates of GNB followed by pseudomonas (13%), enterobacter (13%) and acinetobacter (10%). Others were less frequently isolated.

Over 70% of all isolates were resistant to ampicillin (79%) and carbenicillin (72%); 55, 45 and 43% were resistant to cephalothin, tetracycline and streptomycin, respectively. The great majority of the strains were sensitive to the remaining six drugs.

The hospital isolates were more resistant than the non-hospital isolates to most drugs tested. The hospital strains were also more often multiply resistant (89%) than the non-hospital strains (60%). Sixty-five different resistance antibiograms of 1—10 drugs were observed among 191 strains. More varied types of antibiograms were observed among hospital strains.

The high frequency of multiple drug resistance of the isolates is an indication of the extensive use of antibacterial drugs, indicating the need for a policy for judicious use of drugs.

A retrospective study of clinical characteristics, outcome and prognostic factors of patients with cryptococcosis was undertaken in intensive care units (ICUs) of a medical centre for the period 2000–2005. Twenty-six patients with Cryptococcus neoformans var. grubii infection were identified (16 males, median age 58 years). The most frequent underlying diseases were liver cirrhosis (38·5%), diabetes mellitus (26·9%) and HIV infection (19·2%). The most frequently identified sites of infection were blood (61·5%), cerebrospinal fluid (38·5%) and airways (34·6%). The mean Acute Physiologic and Chronic Health Evaluation II score at ICU admission was 22·46. The ICU mortality rate in these patients was 73·1% (19/26) and there were a further two mortalities recorded after discharge from ICU, reaching a total mortality rate of 80·8% (21/26). Patients with ICU survival >2 weeks had lower rates of HIV infection (P=0·004), less use of inotropic agents during ICU stay (P<0·001) and lower white blood cell counts (P=0·01). After adjusting for clinical variables in the multivariate Cox regression model, diabetes and cryptococcal infection after ICU admission were independent predictors of good long-term prognosis (P=0·015) and HIV infectious status was associated with poor outcome (P=0·012).

Five pigs were treated orally with norfloxacin for 5 consecutive days in two well-separated periods. This was done to determine the lowest dose required to free the pigs of Enterobacteriaceae. In the first period of the study, the animals were treated with 400 mg per day while in the second treatment 800 mg norfloxacin was given. Daily faecal culturing indicated that the faeces became free of Enterobacteriaceae in 3–5 days when treated with 400 mg/day, while all animals were found negative on culturing after 3 days of treatment with 800 mg/day. Investigation of the concentration of norfloxacin in the faeces revealed that a substantial fraction of the dose was either absorbed or inactivated by faecal substances. An in vitro study in faeces confirmed that a substantial part, some 75% of the dose, may have been inactivated by intestinal contents. This finding helps to explain the much lower concentration of 120 mg norfloxacin per kg of faeces in the pig in comparison with the almost tenfold higher concentration reported to develop in man during treatment with an identical dose.

We determined the prevalence of anti-hepatitis B surface antibodies (anti-HBs) among children and adolescents vaccinated for hepatitis B virus in infancy as part of the routine vaccination programme. A representative serum sample of the Israeli population age 0–19 was tested. In a separate pilot study, a booster dose of hepatitis B vaccine was administered to 31 candidates for national service, who were fully vaccinated in infancy and tested negative for hepatitis B surface antibodies at age 17–19 years and anti-HBs antibodies were assessed 8 weeks later. Of the 1273 samples tested, 631 (49·6%) were positive to anti-HBs antibodies. Seropositivity rates were 89·5% among infants aged 6–12 months and declined significantly with age to 20·7% at age 19 years. No differences in seropositivity rates were observed between Jews and Arabs, males and females and those born in Israel and in other countries. Seroconversion rate among the 31 individuals who received a booster dose was 90·3% (95% CI: 75·1–96·6%). We recommend a booster dose for healthcare personnel before starting to work at the health care facility.

In 2011, from August to November, the Monroe County Department of Public Health (MCDPH) investigated 47 salmonellosis cases. Geographical information software (GIS) was used to map the address locations of these cases. The resulting GIS analysis and culture information indicated that there were two distinct clusters of Salmonella that were geographically different. Pulsed-field gel electrophoresis (PFGE) testing was run at the New York State Department of Health Wadsworth Laboratory and identified S. Enteritidis (23 cases) and S. Typhimurium (10 cases). The epidemiological investigation identified Turkish pine nuts as the link between ill S. Enteritidis cases. Pine nut samples sent for laboratory testing were a PFGE match to human isolates with S. Enteritidis. A national recall of Turkish pine nuts ensued. A multistate outbreak was identified as a result of the initial investigation of MCDPH, in which 43 people were infected with the outbreak strain from five states. GIS software and shopper card data provided important tools in the epidemiological investigation.

On 27 April 2015, Washington health authorities identified Escherichia coli O157:H7 infections associated with dairy education school field trips held in a barn 20–24 April. Investigation objectives were to determine the magnitude of the outbreak, identify the source of infection, prevent secondary illness transmission and develop recommendations to prevent future outbreaks. Case-finding, hypothesis generating interviews, environmental site visits and a case–control study were conducted. Parents and children were interviewed regarding event activities. Odds ratios (OR) and 95% confidence intervals (CI) were computed. Environmental testing was conducted in the barn; isolates were compared to patient isolates using pulsed-field gel electrophoresis (PFGE). Sixty people were ill, 11 (18%) were hospitalised and six (10%) developed haemolytic uremic syndrome. Ill people ranged in age from <1 year to 47 years (median: 7), and 20 (33%) were female. Twenty-seven case-patients and 88 controls were enrolled in the case–control study. Among first-grade students, handwashing (i.e. soap and water, or hand sanitiser) before lunch was protective (adjusted OR 0.13; 95% CI 0.02–0.88, P = 0.04). Barn samples yielded E. coli O157:H7 with PFGE patterns indistinguishable from patient isolates. This investigation provided epidemiological, laboratory and environmental evidence for a large outbreak of E. coli O157:H7 infections from exposure to a contaminated barn. The investigation highlights the often overlooked risk of infection through exposure to animal environments as well as the importance of handwashing for disease prevention. Increased education and encouragement of infection prevention measures, such as handwashing, can prevent illness.

We investigated the clinical predictors of methicillin-resistance and their impact on mortality in 371 patients with Staphylococcus aureus bacteraemia identified from two prospective multi-centre studies. Methicillin resistant S. aureus (MRSA) accounted for 42.2% of community-onset and 74.5% of hospital-onset cases. No significant clinical difference was found between patients infected with MRSA vs. methicillin-sensitive S. aureus (MSSA), except that the former were more likely to have had hospital-onset bacteraemia and received antibiotics in the preceding 90 days. After stratifying according to the acquisition site, prior antibiotic use was the only independent predictor of having MRSA in both community-onset and hospital-onset cases. The frequency of inappropriate empirical antibiotic therapy was higher in patients with MRSA than in those with MSSA bacteraemia. However, methicillin resistance was not a predictor of mortality in patients and the clinical characteristics and outcomes of both MRSA and MSSA bacteraemia were similar. This study indicates that there are no definitive clinical or epidemiological risk factors which could distinguish MRSA from MSSA cases with the exception of the previous use of antibiotics for having MRSA bacteraemia, which emphasises the prudent use of glycopeptide treatment of patients at risk for invasive MRSA infections.

Giardia spp. is a common gastrointestinal (GI) parasite of multiple host species, including dogs and humans, with the potential for zoonotic transmission. The risk of GI parasitism in dogs (including Giardia spp.) may increase with park use in urban areas. This study aimed to (1) determine whether park attendance is a risk factor for Giardia spp. infection in dogs and (2) characterize the behavioural and demographic risk factors for Giardia spp. infection in park-attending and non-park-attending dogs. From August to September 2012, a total of 1293 dog owners completed a survey and 860 corresponding dog faecal samples were collected. Dog faeces were screened for Giardia spp. using a direct immunofluorescence assay and associations assessed among behaviours, demographics, and Giardia spp. infection. Main results included off-leash and swimming frequencies within parks as significantly positively associated with Giardia spp. infection in dogs. Dog-owner age was negatively associated with off-leash and swimming frequencies in parks. The results suggest some recreational behaviours in parks and certain demographics are risk factors for parasitism in pet dogs.

Pneumococci form a group of organisms of which the individual strains exhibit wide differences in character. Like the streptococci, certain types of which they closely resemble, they show a variability in their predilections and behaviour bewildering to those who are attempting to classify them. Not only are pneumococci known to cause a great variety of lesions about the body, but they have also been found in the throats of a large proportion of healthy persons who apparently suffer no inconvenience from their presence—Stillman (1916, 1917), Glynn (1923) and others.

The prevalence of antibodies against Entamoeba histolytica was studied in the Mexican population using an immunoenzyme assay in solid phase (ELISA) and semiautomatic equipment. The antigen was a mixture of membrane proteins obtained by Triton X-100 extraction from an axenic culture of Entamoeba histolytica HM1-IMSS. The method was standardized by comparing serum samples from amoebic liver abscess patients with healthy volunteers. From the 60538 samples supplied by the National Seroepidemiology Survey, antibodies were found in 4·49 % (4·32–;4·65% at 95 % confidence limit). More significant titres occurred in the central region of the country. The ratio female to male was 1·25:1. The population living in metropolitan areas had probably been infected at a younger age than those living in the country.

Important differences were found in the seroprevalence obtained by ELISA compared with a study which used indirect haemagglutination (IHA) in the same sample frame.

1. A bacteriological laboratory was provided in the medical departments of two passenger ships—a modern luxury liner cruising in the Mediterranean for 1 month and an older vessel, now out of commission, on a 3 months round voyage through the tropics. Galley hygiene in relation to gastro-enteritis was investigated on both ships.

2. 125 samples of water and iced water were examined. Samples of water chlorinated on the ships were usually satisfactory. Many port waters sampled from the barge or hosepipe were contaminated—some mildly, some profusely. A fault in an ice-making machine led to pollution of ice used for various purposes. Swimming-bath water was usually mildly polluted only; occasionally in the tropics when the baths were very popular the count rose to 1600 Esch. coli per 100 ml.

3. Thirty-five samples of milk, ice-cream and churn washings were examined. English liquid pasteurized milk stored in the cold gave satisfactory results, but the rehydrated dried milk used exclusively on the round voyage through the tropics and swabs from the apparatus used in its preparation were contaminated with Esch. coli. Ice-cream samples from ship I gave satisfactory results, and of two samples of ice-cream powder examined on ship II one was satisfactory and the other gave a poor result. Occasional churns which had been superficially cleaned but not sterilized had a high general and Esch. coli count.

4. 189 samples of food were examined, twenty-two for general and coliform counts only. Results were variable according to foodstuff and atmospheric temperature. Some cold cooked meatstuffs gave low counts and absence of coliform bacilli in 1/10 g.; others had plate counts of 300,000 to 25 million per gram with Esch. coli in 1/1000 dilution, e.g. crayfish ready for the table. Salmonellae were not found in any samples but occasionally small numbers of coagulase-positive staphylococci and non-haemolytic Cl. welchii were isolated.

5. Sixteen samples of imitation cream and washings from savoy bags were examined. Samples from freshly opened cans of cream gave satisfactory results. In whipped cream and in cream from cakes and sweets, Esch. coli was found in 1/1000 dilutions, and rinsings from savoy bags in use gave probable numbers of Esch. coli of 18,000 + / 100 ml. Counts were still high after the bags had been washed and dried and they were far from sterile even after ‘boiling’ and drying.

6. Twenty-three samples of wash water from salad vegetables and fruit had high counts of Esch. coli. After these articles had been washed in water containing 80 p.p.m. sodium hypochiorite, coliform organisms were not found in 100 ml. of water. Potassium permanganate was considered to be of doubtful value. The results of laboratory experiments to confirm the concentration of hypochiorite and time necessary to destroy Esch. coli on lettuce and watercress are shown in Tables 3 and 4.

7. Results from forty-four samples of wash and rinse waters from dish-washing machines and one bowl showed that the temperatures were often too low; with temperatures above 50° C. coliform bacilli were absent in 1 ml. quantities, but waters at temperatures below 42° C. gave probable Esch. coli counts of 1800 + / 100 ml. The bacteriological condition of the crockery and cutlery varied according to the wash and rinse waters. Rinses from metal dish covers gave poor results, with 1800+ Esch. coli per 100 ml. of rinse and occasionally Cl. welchii and coagulase-positive staphylococci. Wash and rinse waters, with temperatures of 35°ndash;42° C. used for pots and pans gave probable Esch. coli counts of 1800 + /100 ml.

8. Rinse waters from twenty cloths used in the galleys, pantries and dining rooms were nearly all heavily contaminated with Esch. coli, with probable numbers of 18,000 + /100 ml.; these counts were reduced to negligible figures by soaking the cloths in chloride of lime.

9. Swabs were taken from thirty-eight cutting-boards and twenty-six surfaces of sinks, shelves and miscellaneous articles. Many boards were heavily contaminated, the probable number of Esch. coli being 18,000 + /100 ml. of diluent; lecithinase-positive clostridia were found also. The boards could be sterilized by brushing with a stout wire brush followed by chlorination.

Other surfaces, and swabs from various knives in the kitchen, including the blade of the slicing machine, frequently gave high counts of Esch. coli.

10. 329 swabs from nostrils and fingers of saloon and galley staffs yielded one cutlure of coagulase-positive staphylococci from 111 nasal swabs and three cultures of coagulase-positive staphylococci and seven of Esch. coli from 218 finger swabs from twenty-seven men.

11. Twenty-eight faecal specimens were examined from fifty-four cases of gastro-enteritis reported on the Mediterranean cruises; salmonellae were not found, but heat-resistant Cl. welchii was isolated from six samples (21%), and the clinical picture was that of Cl. welchii food poisoning.

12. 121 faeces samples from 137 patients with gastro-enteritis were examined chiefly for salmonellae and coagulase-positive staphylococci on the outward leg of the round voyage through the tropics. Salm. typhimurium was isolated from a clinical case and Cl. welchii from one typical case of food poisoning. On the return journey all samples were examined also for Cl. welchii; of thirty-five stool samples from thirty-five patients, six (17%) yielded lecithinase-positive clostridia; salmonellae were not found.

13. Heat-resistant strains of Cl. welchii were also isolated from two chopping-boards, a knife, cold beef, brawn, two wiping cloths, a dish cover, two samples of pie and corned beef.