Experimental infection of the vagina of TO and CBA mice with Mycoplasma pulmonis was enchanced greatly by progesterone treatment. Almost all treated animals became infected, whereas only two-thirds of the untreated TO mice and less than half of the untreated CBA mice did so. Almost 1000-fold more organisms were recovered from treated than from untreated mice and the duration of infection was more than doubled. The enhanced infection in the hormone-treated animals was accompanied by a more severe vaginal polymorphonuclear leucocyte response which reached a maximum two weeks after inoculation of M. pulmonis. In the to mice the eventual decline in cellular response coincided with the gradual disappearance of the mycoplasmal infection. The implications of these findings for genital infections of other animal species are discussed.

Typing of Mycobacterium avium strains obtained in a study of endemic tuberculosis in a Wildfowl Reserve permitted the recognition of two separate infected groups. The main infection was in Anatidae and was due to M. avium, type 1; the other was in chickens used for incubation and brooding and the predominance in it of type 2 agreed with normal experience of birds, pigs and cattle in Britain. Many of the strains isolated from the Anatidae were aberrant and methods used to investigate these are described; two of the strains may belong to a new type. Birds which died from other causes, usually trauma, often had subclinical tuberculosis and 5% of the samples of mud and soil examined yielded M. avium.

Sera sent for routine examination from hospitals in south England and Wales were examined and compared with sera from the normal population. Choroiditis was the only disease syndrome showing a significantly higher proportion of positives than normal.

Cats were shown to be unlikely vectors of toxoplasma infection, at least by scratching.

Thanks are due to many pathologists throughout the country who sent sera and details of cases. Normal children's sera were kindly sent to me by Dr A. D. Evans of the Public Health Laboratory, Cardiff, Dr A. Macrae, Colindale, and Dr Margaret Wilson, Public Health Laboratory, Sheffield. Dr Patricia Bradstreet kindly sent me details of requests for cat scratch antigen.

Mr R. Payne carried out the dye tests and Mr H. J. Godwin of the Department of Pure Mathematics, University College of Swansea, kindly checked the statistical calculations.

Many thanks are due to Dr R. J. Drummond and his staff of the National Blood Transfusion Service (Welsh Region) for supplying the sera from blood donors.

A cross-sectional study was conducted from June 2013 to August 2015 to determine the seroprevalence and possible risk factors for human Toxoplasma gondii infection in Korean, Manchu, Mongol and Han ethnic groups in eastern and northeastern China. A total of 1842 serum samples, including Han (n = 802), Korean (n = 520), Manchu (n = 303) and Mongol (n = 217) groups, were analysed using enzyme-linked immunoassays to detect IgG and IgM T. gondii antibodies. The overall T. gondii IgG and IgM seroprevalences were 13·79% and 1·25%, respectively. Of these groups, Mongol ethnicity had the highest T. gondii seroprevalence (20·74%, 45/217), followed by Korean ethnicity (16·54%, 86/520), Manchu ethnicity (13·86%, 42/303) and Han ethnicity (11·35%, 98/802). Multiple analysis showed that the consumption of raw vegetables and fruits, the consumption of raw/undercooked meat and the source of drinking water were significantly associated with T. gondii infection in the Han group. Likewise, having a cat at home was identified as being associated with T. gondii infection in the Korean, Manchu and Mongol groups. Moreover, the consumption of raw/undercooked meat was identified as another predictor of T. gondii seropositivity in the Mongol group. The results of this survey indicate that T. gondii infection is prevalent in Korean, Manchu, Mongol and Han ethnic groups in the study region. Therefore, it is essential to implement integrated strategies with efficient management measures to prevent and control T. gondii infection in this region of China. Moreover, this is the first report of T. gondii infection in Korean, Manchu, and Mongol ethnic groups in eastern and northeastern China.

This study on Kenyan schoolchildren aims to elucidate the effect of contact with environmental mycobacteria on the development of specific delayed hyper-sensitivity. A series of 12 skin test reagents was employed; eleven of them were prepared from extracts of living mycobacteria and the last was the P.P.D. RT 23. Eight of the new tuberculins were prepared from mycobacteria recovered from the East African environment. A total of 8641 tests were carried out on 4320 children between the ages of 6 and 17 years in four townships. Two of these townships were in fertile agricultural areas and two were in the desert. Just over 80% of the children had received BCG immunization.

The results obtained showed that increasing age, geographical locality and BCG immunization all had a profound effect, and socioeconomic background had some effect, on the pattern of reactivity to the various reagents. The rationale behind the use of the series of new tuberculins and the results obtained with them are discussed in relation to the interacting effects of the factors complicating these results.

Zika virus (ZIKV) is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. Recent scientific evidence on Culex quinquefasciatus has suggested its potential as a vector for ZIKV, which may change the current risk zones. We aimed to quantify the world population potentially exposed to ZIKV in a spatially explicit way, considering the primary vector (A. aegypti) and the potential vector (C. quinquefasciatus). Our model combined species distribution modelling of mosquito species with spatially explicit human population data to estimate ZIKV exposure risk. We estimated the potential global distribution of C. quinquefasciatus and estimated its potential interaction zones with A. aegypti. Then we evaluated the risk zones for ZIKV considering both vectors. Finally, we quantified and compared the people under risk associated with each vector by risk level, country and continent. We found that C. quinquefasciatus had a more temperate distribution until 42° in both hemispheres, while the risk involving A. aegypti is concentrated mainly in tropical latitudes until 35° in both hemispheres. Globally, 4.2 billion people are under risk associated with ZIKV. Around 2.6 billon people are under very high risk associated with C. quinquefasciatus and 1 billion people associated with A. aegypti. Several countries could be exposed to ZIKV, which emphasises the need to clarify the competence of C. quinquefasciatus as a potential vector as soon as possible. The models presented here represent a tool for risk management, public health planning, mosquito control and preventive actions, especially to focus efforts on the most affected areas.

HIV-1 drug resistance can compromise the effectiveness of antiretroviral therapy (ART). A survey of pretreatment HIV-1 drug resistance (PDR) was conducted in Lincang Prefecture of Yunnan Province. From 372 people living with HIV/AIDS initiating ART for the first time during 2017–2018, 322 pol sequences were obtained, of which 11 HIV-1 strain types were detected. CRF08_BC (70.2%, 226/322) was the predominant strain, followed by URF strains (10.6%, 34/322). Drug resistance mutations (DRMs) were detected among 34.2% (110/322) of the participants. E138A/G/K/R (14.3%, 46/322) and V179E/D/T (13.7%, 47/322) were the predominant DRMs. Specifically, E138 mutations commonly occurred in CRF08_BC (19.9%, 45/226). Among the DRMs detected, some independently conferred resistance, such as K65R (1.6%, 5/322), Y188C/F/L (0.9%, 3/322), K103N (0.6%, 2/322) and G190A (0.3%, 1/322), which conferred high-level resistance. The prevalence of PDR was 7.5% (95% CI: 4.6–10.3%) and the prevalence of non-nucleotide reverse transcriptase inhibitor (NNRTI) resistance was 5.0% (95% CI: 2.6–7.4%), which is below the threshold (⩾10%) of initiating a public health response. In conclusion, HIV-1 genetic diversity and an overall moderate level of PDR prevalence were found in western Yunnan. PDR surveillance should be continually performed to decide whether a public health response to NNRTI resistance should be initiated.

1. Two hundred and ten blood samples were obtained from workers in the fish trade. Of these, fifty-one, or 24·2 per cent., gave positive sero-reactions in dilutions of the serum ranging from 1/30 to 1/1000.

2. There was no significant difference in the number of positive sero-reactions occurring in male or female workers.

3. In a control series of 406 blood specimens from individuals not engaged in the fish trade, no positive sero-reactions were obtained.

4. Evidence is adduced that leptospiral infections occur in three grades: (a) severe infections associated with jaundice; (b) mild infections with pyrexia and no jaundice; and (c) latent or inapparent infections with no clinical manifestations.

5. Preventive methods have been detailed which, if put into practice, would, it is believed, reduce the incidence of this disease.

6. Sufficient evidence has been produced to show that this disease is occupational in nature, and as such should be scheduled under the Workmen's Compensation Act.

Acknowledgements. We are indebted to Drs Hill, Goldie and Fullerton of the Department of Medicine for much help in the collection of specimens.

1. The course of disappearance of passive immunity in rabbits injected with diphtheria antitoxin obtained from goats, men, guinea-pigs and cows, consists of the same three phases that follow the injection of horse serum.

2. The rabbits examined were more responsive to goat, human and guinea-pig serum than to horse and cow serum.

3. The course of disappearance of passive immunity in rabbits, horses and guinea-pigs injected with homologous antitoxin, consists of Phases A and B only, and Phase B is far slower than when heterologous serum is injected into rabbits.

4. Sheep and goats eliminate antitoxin obtained from a horse at a very slow rate, and Phase C is hardly detectable.

5. Natural immunity of horses to diphtheria toxin is gradually acquired by a number of increasing responses to external stimuli.

A comparison was made between a macrotechnique in tubes and a microtechnique in plastic plates for complement-fixation tests, using strains of three subtypes of the Asia 1 type of foot-and-mouth disease (FMD) virus. The results obtained with these techniques were found to be comparable and delineated the antigenic relationships of the three strains employed. The microtechnique was considered to be both economical with reagents and capable of similar accuracy and reproducibility to that of the standard method in tubes. It was concluded that the antigenic analysis of subtype strains of FMD virus can be conveniently carried out by the use of the microtechnique as described.

Almost all cases of human listeriosis are foodborne, however the proportion where specific exposures are identified is small. Between 1981 and 2015, 5252 human listeriosis cases were reported in England and Wales. The purpose of this study was to summarise data where consumption of specific foods was identified with transmission and these comprised 11 sporadic cases and 17 outbreaks. There was a single outbreak in the community of 378 cases (7% of the total) which was associated with pâté consumption and 112 cases (2% of the total) attributed to specific foods in all the other incidents. The proportion of food-attributed cases increased during this study with improvements in typing methods for Listeria monocytogenes. Ten incidents (one sporadic case and nine outbreaks of 2–9 cases over 4 days to 32 months) occurred in hospitals: all were associated with the consumption of pre-prepared sandwiches. The 18 community incidents comprised eight outbreaks (seven of between 3 and 17 cases) and 10 sporadic cases: food of animal origin was implicated in 16 of the incidents (sliced or potted meats, pork pies, pâté, liver, chicken, crab-meat, butter and soft cheese) and food of non-animal origin in the remaining two (olives and vegetable rennet).

Infection with STEC O157 is relatively rare but has potentially serious sequelae, particularly for children. Large outbreaks have prompted considerable efforts designed to reduce transmission primarily from food and direct animal contact. Despite these interventions, numbers of infections have remained constant for many years and the mechanisms leading to many sporadic infections remain unclear.

Here, we show that two-thirds of all cases reported in England between 2009 and 2015 were sporadic. Crude rates of infection differed geographically and were highest in rural areas during the summer months. Living in rural areas with high densities of cattle, sheep or pigs and those served by private water supplies were associated with increased risk. Living in an area of lower deprivation contributed to increased risk but this appeared to be associated with reported travel abroad. Fresh water coverage and residential proximity to the coast were not risk factors.

To reduce the overall burden of infection in England, interventions designed to reduce the number of sporadic infections with STEC should focus on the residents of rural areas with high densities of livestock and the effective management of non-municipal water supplies. The role of sheep as a reservoir and potential source of infection in humans should not be overlooked.

A broad division of the opportunist mycobacteria has been defined under the name of ‘dysgonic nonchromogens’. The classification was attempted of 68 strains isolated from man in England and Wales, of which 54 at least appeared to be clinically significant. The means used were chiefly drug sensitivity, arylsulphatase activity, specific agglutination, lipid analysis and pathogenicity tests on fowls. On the results, a new definition is proposed for the species M. avium, extending beyond the boundaries of pathogenicity for birds, and a scheme put forward for its division into two types. In addition, two provisional new species and a group of ‘para-avian’ bacilli have been recognized and defined. The remaining 16 strains included six with ‘Battey’ serotypes but otherwise could not be classified. The need for standardization of fowl tests has been noted together with their diminished importance in the field of classification with the emergence of new in vitro methods of examination.

An identifying characteristic of Staphylococcus aureus is the production of staphylocoagulase (coagulase). The aim of this study was to determine the clonal distribution of coagulase gene (coa) variants within populations of S. aureus defined by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and protein A variation. The N-terminal region of the coa gene from 43 methicillin-susceptible (MSSA) and 252 methicillin-resistant (MRSA) S. aureus human isolates and 9 animal S. aureus isolates was amplified and digested with HinfI. Twelve types were identified amongst the MSSA isolates and the majority (93%) of MRSA isolates were assigned to 5 of the 12 types. MLST and PFGE analysis identified epidemic populations of MRSA and each epidemic population was characterized by a different coagulase type. Nine of the 12 MLST-defined clonal complex ancestral genotypes recently described each carried a different coagulase type suggesting that coagulase evolution and the evolution of the clonal complexes are intimately related.

1. Following an epizootic of louping ill on certain farms in south-west Ayrshire in 1960, a long-term study of several farms was initiated.

2. The flocks on two hirsels of one farm were studied during spring and early summer of 1961. Although only one lamb death was confirmed as due to louping ill, the infection rates in sentinel hoggs on the two hirsels were 50–60. and 11% respectively. The difference between the hirsels is probably attributable to the difference in the amount of tick habitat on them.

3. The ewes were bled in March and June and their lambs in June. Haemagglutinin inhibition (HI) and neutralization tests revealed that the HI antibody is much shorter lasting than neutralizing antibody. Many ewes, therefore, had neutralizing but not HI antibody. Otherwise agreement between the tests was good. In March almost all the ewes aged 3 years or more had antibody. Of the gimmers (2-year-olds) about two-thirds on one hirsel and one-third on the other had antibody in March: by June almost all the former and about half of the latter had antibody.

4. About two-thirds of the lambs had the same antibody status as their mothers in June and almost all the rest had less antibody than their mothers. Serological evidence suggestive of louping ill without recognizable clinical disease was found in six lambs and a further lamb recovered from clinical disease.

5. Revaccination of two-thirds of the flock failed to cause any detectable change in antibody status.

6. The epidemiology and pathogenesis are discussed in relation to immunity and infection rates, and to the design of control measures.

We are greatly indebted to the late Mr James Murdoch at Dalmellington, Mr John Murdoch at Dalcairnie Farm, and Mr David Murdoch at Knockgray Farm for permission to work on their farms and for all the help they gave us during the study.

The growth of L. australis B in the kidneys of young mice which become carriers was followed after experimental intraperitoneal infection. There was a primary growth corresponding to generalized acute infection and terminated at the time of appearance of antibody. A secondary growth bf leptospirae followed in the kidneys alone about 7–10 days after infection, coinciding with the onset of leptospiruria and recovery from infection. Subsequently mice carried about 106–107 leptospirae in their kidneys permanently.

The leptospirae in the urine or in the kidneys of carriers were resistant to the action of antibody in the serum or urine of the host animal, or in rabbit antisera prepared against mouse-renal leptospirae or against cultured leptospirae of the infecting strain. No antigenic differences were detected between renal and cultured leptospirae. An analogous situation is the growth in vitro of leptospirae in homologous antiserum. The mechanism permitting growth of leptospirae in homologous antiserum in vivo or in vitro is unknown.

The carrier condition results from the ability of virulent leptospirae to (i) grow in the host and produce lesions in the primary, acute generalized infection, (ii) grow in renal tubules in the presence of antibody.

A newly developed lectin neuraminidase test (LNT) and a panel of mouse monoclonal and post-infection ferret antibodies have been used to analyse antigenic drift in N1 neuraminidases of influenza A viruses isolated between 1933 and 1957 and also between 1977 and 1980. Significant antigenic differences were detected among the ‘early’ (1933–57) viruses since the NA of viruses isolated one year apart could be distinguished serologically. The NA ofthe ‘re-emerged’ virus A/USSR/92/77 (H1N1) was antigenically related but not identical to influenza A viruses isolated in 1949 (A/Paris/49 (H1N1), A/Geneva/49 (H1N1)) which thus predates the previously observed antigenic similarity of A/USSR/77 with A/FW/50 (H1N1) virus.

This study aimed to investigate the relationship between hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) in the ovary and vertical transmission of HBV. HBV DNA and HBV cccDNA were assayed in the ovaries of 33 pregnant women who were positive for HBV DNA. The HBVM (HBV markers, including HBsAg, HBsAb, HBeAg, HBeAb, HBcAb) level and the HBV DNA content in peripheral blood of infants were measured. The overall positive rate of HBV DNA and HBV cccDNA in samples was 51·52% (17/33). The intrauterine infection rate of the infants was 12·12% (4/33). When HBV DNA and HBV cccDNA were both positive, the intrauterine infection rate of infants was significantly higher than when they were both negative (P<0·05). Levels of HBV cccDNA and the rate of positive samples were significantly higher in mothers with infants with intrauterine infection than in those without (P<0·01 and P<0·05, respectively). HBV can infect the human ovary and may transmit to the filial generation via the ovum.

Two waves of vomiting and/or diarrhoea affected approximately 215 of the 715 passengers on a Caribbean cruise ship. The outbreak was independently associated with eating cream-filled pastries at two separate meals. Staphylococcus aureus phage type 85/+ was isolated from cases and pastry cooks, but not from controls. This is the first well-documented outbreak of staphylococcal food poisoning on a cruise ship.

A study of cleaning and disinfection methods in a variety of types of catering premises has been carried out. The level of bacterial contamination of the hands and of equipment was related to cleaning methods and to the type of catering establishment. Wiping cloths were frequently contaminated with Escherichia coli, and these may be important reservoirs of bacteria for contamination of the hands of catering staff. Regular and efficient cleaning of food surfaces and equipment was found to be more important than the use of a disinfectant as part of the cleaning process. Methods for reducing the risks of cross-contamination in catering premises are discussed.