Variation amongst Achromobacter-like strains was examined by DNA restriction endonuclease digestion and rDNA gene patterns generated using a non-radioactive probe. Chromosomal DNA was extracted from 12 cultures representing Achromobacter groups B, E and F, all from human blood cultures. DNA fingerprinting using EcoRI, HaeIII or HindIII sub-divided the strains in a similar manner to that obtained by their protein patterns. The HaeIII patterns, with their small number of bands, were the easiest to interpret. The EcoRI patterns included a species-specific triplet of bands but minor band patterns allowed further differentiation. The Achromobacter group F strains comprised a separate taxon and were distinct from the group B and E strains by all techniques examined. The study demonstrates that, in addition to total DNA digest analysis, rDNA gene restriction patterns provide a simple but discriminatory electrophoretic method for distinguishing within Achromobacter groups B and E.

(1) Samples of faeces of 391 cows in apparently good health have been examined and it has been demonstrated that 6 (1.53 per cent.) of the cows were excreting tubercle bacilli.

(2) When the faeces of almost all the cows on founrteen farms were examined it was found that five cows on four farms were excreting tubercle bacilli.

Our thanks are due to the Medical Research Council for the grant which enabled us to carry out this investigation.

An enzyme-linked immunosorbent assay (ELISA) incorporating the sensitive biotin-streptavidin system was developed to detect IgG antibodies to tetanus toxoid in human serum. Serum samples obtained from 557 normal persons aged 1–65 years from different areas in New Zealand were tested. The proportion of those immune ranged from 60–93% in males, and from 46–86% in females. In the 1–9 years age group 85% were immune. The indirect ELISA is suitable for serological surveys as it is simple to perform, economical and reproducible.

Measles elimination goals have been adopted in a range of countries, sub-regions, and regions since the WHO declared an elimination goal by 2015 or 2020. All countries attempt to achieve and maintain high coverage through routine immunization programmes. This routine strategy, however, does not ensure the elimination goal of measles. Many developed countries, such as the United States, that have succeeded in interrupting measles transmission earlier, are now experiencing outbreaks with an increasing number of cases. Using a stochastic, age-structured model of measles vaccination dynamics, we explore and characterize the transient dynamics of measles susceptibility in the years following the implementation of routine vaccination at the herd immunity threshold. We demonstrate how a population could face risks of potentially large outbreaks even within few years of vaccination. We characterize different risk profiles depending on the incidence pattern in the years prior to vaccination. These results suggest that the classic critical vaccination threshold is necessary to achieve herd immunity, but not sufficient to prevent long periods of transient, super-critical dynamics. Our results suggest the need of future work for more careful monitoring of the impacts of current immunization programmes, and developing models that take into account more complicated vaccination strategies, demographic factors, and population movements.

Acute respiratory infections (ARIs) are the most important infectious cause of death, but there is less information of their burden in the community. This study describes the burden of ARI in a cohort of 50 Iranian families visited weekly over 2 months. Eighty-one out of 113 (72%) children and 29/103 (28%) adults had a total of 124 episodes of ARI. Seventy-five per cent of the episodes occurring in children were primary/co-primary compared to 40% of those in adults (P<0·01). Children were more likely to be the first symptomatic cases and infections were frequently transmitted within the family. Frequencies were lowest among adults, low among infants aged <6 months and highest among children aged <5 years (P<0·01). Winter episodes occurred more frequently in January (P<0·01). The high frequency and apparent transmissibility of ARI in this cohort highlights its enormous burden in the community.

This study aimed to estimate the disease burden of hepatitis E in a rural region in China. A total of 489 hepatitis E cases were reported according to a community-based survey in an active hepatitis surveillance system between 2008 and 2015, the questionnaire and record-review methods were constructed to evaluate the economic and health burden of hepatitis E virus infections from societal perspectives. All costs were converted to US$ in 2015. The age-standardized cumulative incidence rate was 107·9/100 000, and the median age-standardized annual incidence rate was 16·5/100 000. The median direct, indirect, and intangible cost were $1046·0, $49·1, and $77·3/patient, respectively, and the median economic burden per patient was $1836·5, which accounted for 51·2% of per capita disposable income. Moreover, the median quality-adjusted life year and visual analogue scale score were 0·7 and 70·0/case, respectively. Both economic burden and health burden of inpatients was more serious than that of outpatients (P < 0·001). Disease burden of hepatitis E is heavy on patients, their families, and society. More studies on the disease burden of hepatitis E are necessary to increase social awareness of the disease and confirm reasonable disease-control measures.

Campylobacter jejuni/coli strains from 164 chickens were serotyped by the methods previously described by Penner et al. and Lior et al. The chickens were sampled during breeding from hatching to the age of 42 weeks. The birds were housed, in two separate groups, under different environmental conditions, (for comparison of the effect of hygienic precautions on the transmission of the bacteria during breeding). In the group where the hygienic conditions could be controlled to a greater extent, the chickens became colonized later in the breeding chain and with only one single campylobacter strains.

Antimicrobial resistance (AMR) in pig populations is a public health concern. There is a lack of information of spatial distributions of AMR genes in pig populations at large scales. The objective of the study was to describe the spatial pattern of AMR genes in faecal samples from pig farms and to test if the AMR genes were spatially randomly distributed with respect to the geographic distribution of the pig farm population at risk. Faecal samples from 687 Danish pig farms were collected in February and March 2015. DNA was extracted and the levels of seven AMR genes (ermB, ermF, sulI, sulII, tet(M), tet(O) and tet(W)) were quantified on a high-throughput real-time PCR array. Spatial differences for the levels of the AMR genes measured as relative quantities were evaluated by spatial cluster analysis and creating of risk maps using kriging analysis and kernel density estimation. Significant spatial clusters were identified for ermB, ermF, sulII and tet(W). The broad spatial trends in AMR resistance evident in the risk maps were in agreement with the results of the cluster analysis. However, they also showed that there were only small scale spatial differences in the gene levels. We conclude that the geographical location of a pig farm is not a major determinant of the presence or high levels of AMR genes assessed in this study.

Patients with a clinical diagnosis of dengue but negative by serological testing were studied for rubella infection. Paired sera were obtained from 69 patients during an outbreak in Yucatán, México. The presence of specific anti-viral IgM in the acute sera was considered as diagnostic for rubella infection. The immunoglobulin was determined by measuring the difference in the inhibition of hemagglutination between the non-reduced and the reduced fractionated sera. Immunoglobulins were separated by sucrose density centrifugation. Acute rubella infection was found in 7 (10·1%) of the patients. These results demonstrate active rubella infection in patients clinically diagnosed as dengue.

A study of the distribution of subtypes ad and ay among sera from hepatitis B antigen-positive subjects in North West England and North Wales revealed a marked contrast between symptomless carriers among whom ad predominated and patients with acute hepatitis the majority of whom were ay. Those with hepatitis associated with drug addiction or other forms of ‘needle transmission’ were almost all of subtype ay. On the other hand in cases of ‘sporadic’ hepatitis without evidence of parenteral exposure subtypes ad and ay are about equally distributed.

These findings are similar to those reported from other countries in Northern Europe and North America. Although geographical and social factors clearly affect the distribution of the two subtypes it is suggested that the virus of subtype ay may be more readily transmitted than subtype ad by parenteral routes involving small amounts of blood.

Two hundred and twenty-two infants and fifty-one staff were examined for carriage of Staphylococcus pyogenes and Gram-negative bacilli, and the presence of these bacteria in the ward environment was also investigated. Staphylococci were phage-typed and tested for sensitivity to antibiotics. Assessment of clinical infection caused by these bacteria was made.

Infant carriage of Staphylococcus pyogenes was maximal on the sixth day, 73·1 % of umbilical swabs yielding significant growth. Carriage of Gram-negative bacilli was maximal on the fifth day, 31·7% of umbilical swabs being positive. Where special nursing was enforced, i.e. premature baby unit, isolation of Gram-negative bacilli was very infrequent.

The low nasal carriage of staphylococci seen in infants and nursing staff is attributed to traces of penicillinase-resistant penicillins in the ward air.

Staphylococcus pyogenes was recovered from 23 % of ward surfaces, and constituted 0·7% of the air-borne flora. In contrast, Gram-negative bacilli were recovered from 4·7 % of surfaces, and composed only 0·15% of the air-borne flora.

Phage group I constituted 73·0, 44·9 and 41·2% of strains from infants, staff and ward environment respectively.

Antibiograms were grouped into three categories, A, B and C. Category A (sensitive to chloramphenicol, erythromycin and methicillin but penicillin-resistant) composed 79·0% of infants' strains, being found mostly in group I, but was rare among staff strains.

Of 54 specimens taken from 40 infants showing evidence of infection, Staphylococcus pyogenes was isolated from 16, of which 14 were category A. Gram-negative bacilli were isolated 7 times. Only 21 infants required antibiotic therapy (9·3%) and none were infected with Gram-negative bacilli—this contrasts with the frequency of these bacilli in nursery infection today.

Ward air is considered to be the main depot of Staphylococcus pyogenes. Infant ‘dispersers’ are probably the principal source of the air-borne staphylococci. Infants and staff abstract from the air those staphylococci which become their colonizing strains. No transfer is thought to occur from the staff to the infants. Transmission of Gram-negative bacilli is similar in that the infants are the principal source and the air the main depot of these bacteria. Nasal colonization by Gram-negative bacilli is low, this is possibly due to poor colonizing properties. Infant umbilical carriage almost certainly results from endogenous faecal spread.

We are grateful to Dr J. C. Gould, Director, Central Microbiological Laboratories, Edinburgh, for his continued interest and advice, and to Mr J. C. Ferguson and Mrs M. M. Winton for skilled technical assistance. This study would not have been completed without the co-operation of Sisters McCartney and Struthers and their nursing staff.

The relation of salmonella isolation efficiency and the size of inoculum introduced from a buffered peptone water culture of sewage polluted water into strontium chloride B medium was investigated. Two separate studies were made, one using enrichment at 37°C, the other at 43°C. From these trials, two inocula suitable for efficient salmonella isolation were determined. Using this information, strontium chloride B medium was compared with modified Rappaport's broth (R25). The inoculum used with R25 was 0·005 ml, determined in an earlier study. Two incubation temperatures were employed with strontium chloride enrichment (37 and 43°C). Rappaport's medium was incubated at 37°C only. Elevated temperature enrichment at 43°C improved the performance of strontium chloride B, but Rappaport's broth still gave significantly better results. This supports earlier studies on simplification of salmonella isolation and standardization of routine technique on a single enrichment medium: Rappaport broth (R25) incubated at 37°C.

An examination was made of 200 Wassermann sera, thirty-eight sera from typhoid, twenty-five from paratyphoid B and thirty-one from tuberculous cases, for somatic agglutinins to a range of Salmonellas representative of the O groups then available.

In the Wassermann sera O agglutinins, except to Bact. typhosum and Bact. paratyphosum B, were rare, and the titres against these organisms were low, attaining a titre of 1: 80 against Bact. typhosum in one serum only.

The sera of the enteric cases mostly possessed agglutinins to both Bact. typhosum O and Bact. paratyphosum B O. Cross-relations with Bact. paratyphosum A, Bact. london and, to a less extent, Bact. paratyphosum C, were common in the typhoid sera. Otherwise there was no evidence of relation amongst the somatic groups tested.

The response to T.A.B. inoculation of fifteen individuals suggested also the relation of some organism in the vaccine to Bact. london and its probable lack of relation to the other somatic groups.

There was no evidence of increased frequency of Salmonella agglutinins in tuberculous cases.

The cross-relations of the Salmonellas was found to be due to the possession of minor antigenic components and not to possession of X antigen, which was absent from the suspensions used. X agglutinins were not more frequent in the pathological than in the Wassermann sera.

The relation of these findings to the diagnostic agglutination test is discussed, and the possibility of error consequent upon the use of suspensions containing X antigen is pointed out.

A survey of mild respiratory disease in a primary school was undertaken over a 2-year period to determine which of the newer respiratory viruses were responsible for these illnesses.

The over-all isolation rate was low but a wide variety of viral agents was isolated.

None of these caused epidemics but it is suggested they may be the cause of a low but constant absentee-rate throughout the year.

Salmonella is the second most commonly reported human foodborne pathogen in England and Wales, and antimicrobial-resistant strains of Salmonella are an increasing problem in both human and veterinary medicine. In this work we used a generalized linear spatial model to estimate the spatial and temporal patterns of antimicrobial resistance in Salmonella Typhimurium in England and Wales. Of the antimicrobials considered we found a common peak in the probability that an S. Typhimurium incident will show resistance to a given antimicrobial in late spring and in mid to late autumn; however, for one of the antimicrobials (streptomycin) there was a sharp drop, over the last 18 months of the period of investigation, in the probability of resistance. We also found a higher probability of resistance in North Wales which is consistent across the antimicrobials considered. This information contributes to our understanding of the epidemiology of antimicrobial resistance in Salmonella.

Detailed screening of the patients and staff in a unit specializing in liver disease was carried out over a year to ascertain whether transmission of the serum hepatitis virus was occurring and whether the situation was comparable in any way to that found in a Renal Haemodialysis Unit. Of the 154 patients with liver disease tested on admission, 6% were found to have Australia antigen in the serum and throughout the year there were rarely less than two patients in the ward at any one time with positive serum. No instances of clinical hepatitis were detected in the other patients following their stay in the ward or in their attendant medical, nursing and lay staff. Six staff members were found to have Australia antigen in their serum. In four of these, all nurses, it was present in the first sample tested and so the infection may have been acquired earlier. Temporary elevations in both plasma bilirubin and serum aspartate aminotransferase levels were found in another five staff members whose serum was negative for Australia antigen and who clinically were well. In a further eight and apparently healthy staff members, an isolated but persistent elevation of the plasma bilirubin was noted. In both groups these changes could represent the spread of subclinical infectious hepatitis and it is recommended that in units dealing with ‘liver patients’ not only should considerable care be taken during diagnostic and therapeutic procedures but the medical and nursing staff should be screened at regular intervals.

The aim of this work was to use experimental infection data of human influenza to assess a simple viral dynamics model in epithelial cells and better understand the underlying complex factors governing the infection process. The developed study model expands on previous reports of a target cell-limited model with delayed virus production. Data from 10 published experimental infection studies of human influenza was used to validate the model. Our results elucidate, mechanistically, the associations between epithelial cells, human immune responses, and viral titres and were supported by the experimental infection data. We report that the maximum total number of free virions following infection is 103-fold higher than the initial introduced titre. Our results indicated that the infection rates of unprotected epithelial cells probably play an important role in affecting viral dynamics. By simulating an advanced model of viral dynamics and applying it to experimental infection data of human influenza, we obtained important estimates of the infection rate. This work provides epidemiologically meaningful results, meriting further efforts to understand the causes and consequences of influenza A infection.

The virus of Aujeszky's disease (pseudo-rabies) has been found to have a particle size of 100—150 mμ. Two strains were employed in these experiments, one that of Aujeszky, and the other Shope's “mad-itch” strain. The results with both strains were identical.

A retrospective survey of Coxiella burnetii infection in North-Western England and North Wales was made in five Public Health Laboratories for the years 1962–6 inclusive. Groups of the normal population and of persons occupationally exposed to infection were tested for the presence of antibody and the incidence of infected milk was investigated in seven counties.

Forty-one cases of C. burnetii infection were diagnosed in 7046 patients investigated serologically for the presence of viral and rickettsial antibodies. In just over a quarter of the patients there was evidence of occupational hazard or a history of drinking raw milk. The remainder gave no relevant history.

We would like to express our thanks to Dr C. M. Patricia Bradstreet of the Standards Laboratory, Colindale, for the supply of antigen, and to the numerous clinicians who allowed us access to their case records.

The Middle East respiratory syndrome coronavirus (MERS-CoV) is caused by a novel coronavirus discovered in 2012. Since then, 1806 cases, including 564 deaths, have been reported by the Kingdom of Saudi Arabia (KSA) and affected countries as of 1 June 2016. Previous literature attributed increases in MERS-CoV transmission to camel breeding season as camels are likely the reservoir for the virus. However, this literature review and subsequent analysis indicate a lack of seasonality. A retrospective, epidemiological cluster analysis was conducted to investigate increases in MERS-CoV transmission and reports of household and nosocomial clusters. Cases were verified and associations between cases were substantiated through an extensive literature review and the Armed Forces Health Surveillance Branch's Tiered Source Classification System. A total of 51 clusters were identified, primarily nosocomial (80·4%) and most occurred in KSA (45·1%). Clusters corresponded temporally with the majority of periods of greatest incidence, suggesting a strong correlation between nosocomial transmission and notable increases in cases.