The examination of the spleens of 24 pigs and 10 calves and internal organs from 12 other pigs, all passed as healthy and fit for human consumption, failed to show the presence of any organisms belonging to the Gaertner group. One para-Gaertner bacillus was isolated in pure culture from the spleen of one of the calves.

The spleens of the 24 pigs and 10 calves were also examined for the presence of aerobic organisms generally. Exactly half of the pig and half of the calf spleens were sterile, the remaining 50 per cent, containing bacilli which were not completely identified but were mostly B. coli, non-lactose fermenters allied to B. coli, streptococci and staphylococci. All the organs were examined within a few hours of death. There was no correlation between interval since death and bacterial content nor any relationship to the age of the animal. The bacteria were evidently present in these organs at the time of death.

An extensive series of examinations of sera of animals passed as healthy showed that in a considerable proportion of them specific agglutinins were present against one or other member of the Gaertner group. These agglutinins were absent in all the calves, were mostly absent from sheep, but were fairly well developed in 40 to 50 per cent. of the pigs, cows and oxen examined. They were also present in a considerable proportion of the horses tested. The failure to demonstrate these agglutinins in the calf and their definite development in many of the cows and oxen sera suggest that they are not present in the new born animal but develop later in life. The available data is insufficient to enable a definite opinion to be given as to whether these positive reactions with Gaertner strains are to be ascribed to an old infection with these bacilli but they suggest this possibility.

As a practical point these results show that the demonstration of the presence of agglutinins, in moderate amount, against this group of bacilli in a suspected animal cannot be accepted in itself, and without further corroborative evidence, as proof of an existing infection with these organisms or as conclusive evidence connecting the animal with an outbreak of food poisoning. Much less so can the presence of such agglutinins be accepted as evidence warranting the condemnation of the carcase as unfit for food.

Amongst the animals examined suffering from definite disease one cow which died of septic poisoning showed the presence of a considerable amount of specific agglutinin in its serum, but the other bacteriological data was sufficient to say that the cause of death was not a Gaertner group infection.

The 48 rats examined were selected as showing no macroscopic evidence of Gaertner group infection and from none of them was a member of this group isolated, although five para-Gaertner strains were found which very closely resembled these bacteria.

In nearly every case the sera of these rats failed to show the presence of any Gaertner group agglutinins. This fact is of particular interest in view of the rather different findings which Read and I obtained with another series of rats from a different source and where the possibility of infection with Danysz virus (a Gaertner group organism) was likely. They add weight to the view that in these (mostly young) animals the presence of Gaertner group agglutinins to any considerable extent is evidence of an old infection with a member of this group, and is confirmatory evidence in favour of the agglutinin results with animals used for food being of a similar origin.

The absence of any correlation between the presence of the six para-Gaertner strains and the presence of agglutinins against true Gaertner bacilli is in favour of the view I have expressed from my earlier work, that there is no relationship between these two groups of organisms and that the para-strains cannot be considered as modified Gaertner organisms which under favourable conditions can revert to that type.

The examinations of specimens from diseased animals are too few to enable any deductions to be drawn, but I remain strongly of opinion that work along these lines is likely to throw valuable light upon the etiology of food poisoning and should be systematically undertaken by those who are in a position to obtain and examine such material.

1. Disinfection curves obtained from data on the action of phenol on Bact. coli at 35° C. under conditions such that unfavourable circumstances, other than the presence of the germicide, were as far as possible eliminated, have been used for the calculation of the concentration exponent for phenol, i.e. n in the formula Cn x t = K. The death-rate was not constant throughout the germicidal process but showed initially a phase of slow but increasing death-rate which merged gradually into a phase which was treated (for reasons given) as one of constant rate. This was also the maximum rate for any given phenol concentration.

2. The virtual sterilization times (v.s.t.'s), i.e. the times in min. required for the mortality to reach 99·999999 % as determined by slight extrapolation of the log survivors-time curves, the 99·9 % mortality times and the 99 % mortality times could all be used for the calculation of values of n for phenol as they all gave satisfactory linear relations between log concentration and log time.

3. The 50 % mortality times did not show a satisfactory linear relation between log phenol concentration and log time over the full concentration range, and at this mortality level the concentration exponent appeared to increase for concentrations above 4·62 g. phenol per 1.

4. The value of n varied according to the mortality level chosen. It was 5·8421 ± 0·1876, 6·6062 ± 0·2034 and 6·9638 ± 0·2164 when the v.s.t.'s, 99·9 % mortality times or 99 % mortality times were used. The differences between the first and second and first and third values are significant, but that between the second and third values is not. The value calculated from the v.s.t.'s is regarded as being the most important.

5. Evidence was obtained that, as expected on theoretical grounds, n increases for very low concentrations of phenol. If the aberrant value obtained at the lowest phenol concentration be omitted from the calculations, the value of n calculated from the v.s.t.'s becomes 5·6588 ± 0·1422, but the decrease is not significant.

6. The maximum death-rate was related to the phenol concentration according to the expression km = 9·1743 × 10−6C5·0752, where km is the maximum (logarithmic) death-rate per min. and C the concentration of phenol in g. per 1.

Enterotoxigenic Escherichia coli (ETEC) adhere to the intestinal mucosa by a number of fimbrial colonization factors (CFs) that have been claimed to induce only type-specific immunity. However, adult Bangladeshi patients infected with CFA/I-expressing bacteria, developed significant plasma IgA antibody responses, as determined by enzyme-linked immunosorbent assay, not only against the homologous fimbriae but also against several heterologous CFs, i.e. CS1, CS2, CS4 and PCFO166 fimbriae. In contrast, North American volunteers, who had probably not been infected by ETEC previously, responded with serum IgA against CFA/I fimbriae but not against any other CFs after symptomatic infection with CFA/I-expressing ETEC. Thus, infection with CFA/I-expressing bacteria may boost immune responses against CFs with a related amino acid sequence in previously primed subjects.

A retrospective study of group A streptococcal (GAS) infections was performed for the period 1985–2002 in an area of central Italy. Although very severe diseases such as streptococcal toxic shock syndrome (STSS) were observed, a general increase in invasive infections was not found. Isolates of GAS were classified by M protein genotyping (emm typing) and analysed according to their origin from invasive and non-invasive infections. The predominant emm types were types 1, 4 and 12, followed by types 3, 6 and 28. During the study period the proportion of isolates of types 1 and 12 fell, while other types (3, 6, 22, 28 and 77) appeared. Isolates from invasive and non-invasive infections shared several emm types; however, most invasive strains belonged to five types only (types 1, 4, 12, 28 and 77), while non-invasive isolates were generally more heterogeneous.

Aeromonas has been recognized as an important enteropathogen, but factors related to its virulence have not been clarified. For most enteric pathogens, attachment is a prerequisite for infection and for the effective delivery of toxins to the intestinal epithelial cells. We examined a total of 273 strains isolated from stool, food and environmental specimens by an assay for mannose-resistant adhesion to INT407 cells in vitro. Seventeen of the 102 faecal isolates were adhesive strains with more than 10 bacteria adhering per cell, while only 2 of the 118 isolates from foods and river water adhered to the cells (P < 0·001). It is possible that the adhesion might serve as a marker for discrimination between the pathogenic and nonpathogenic isolates. The 8 highly adhesive strains with more than 20 adhering organisms per cell were scrutinized for the mechanism of adhesion. No correlation was apparent between the adhesion to INT407 cells and hydrophobicity. It was noted that fucose inhibited the adhesion of four strains as well as haemagglutination by them. Electronmicroscopic studies showed the presence of flexible and curvilinear fimbriae in only 2 of the 8 highly adhesive strains.

A multidrug resistant (MDR) variety of Salmonella typhi emerged as the cause of epidemic typhoid fever in some Asian countries including India, during the late 1980s. We faced the epidemic from April 1990 to the first quarter of 1993. However, during this period we continued to isolate chloramphenicol sensitive (CS) S. typhi also. The relative prevalences showed that the frequency of CS variety was unaffected by the epidemic of MDR variety. This is an unusual epidemiological pattern, which indicates that there may have been factors which favoured the epidemic of the MDR variety but not the CS one.

The fluorescent antibody technique was used to investigate an epidemic of Klebsiella infection in a urological ward and to trace the probable source to a contaminated sink in the treatment room. It was also shown that cross infections by particular capsular types were very common within each ward. Certain types of Klebsiella occurred in cut-flower water but could not be associated with the types infecting the patients.

Antibiotic resistance patterns within one capsular type were found to vary whether the type was from different sources in one patient or from different patients in the same ward. One capsular type was observed to develop resistance to increasing numbers of antibiotics over a 3-year period. This was probably due to the acquisition of R-plasmids. There also appeared to be a relation between capsular type and the site of infection.

The frequency of Klebsiella infections in the urological wards dropped significantly after up-grading the treatment room, improving catheter storage and reducing ampicillin use.

This study attempts to determine whether or not livestock are becoming more susceptible to epidemics of salmonella infections by the analysis of published data on the annual number of reported infections in various animals. The number of incidents reported each year may be subject to a variety of biases due to temporal and geographical differences in reporting practices. This study analysed these reports by the calculation of diversity indices which are not subject to some of these potential biases. The relationship between the ecological concept of niche width and the diversity of species or types occupying that niche is discussed. The diversity of salmonella types reported in fowl has shown a highly significant decline over the 13-year period 1976–88. It is suggested that this declining diversity may be related to the declining niche width of the biotope available to this pathogen. Although speculative, this reduction in niche width could be related to a declining genetic diversity in the host animals or to an increasing intensification of animal husbandry.

Despite the existence of a close serological relationship between the entero-viruses Swine Vesicular Disease (SVD) and Coxsackie type B5 (Cx B5), the administration of this Coxsackie virus type to susceptible pigs by various routes failed to produce clinical disease.

Viraemia was not detected after exposure but virus was recovered intermittently from faeces and buccal swabs. A mixed virus population was demonstrated in faecal cultures from some pigs, including Coxsackie virus type B5 and other agents, presumably native pig enteroviruses. The Coxsackie virus persisted in faeces in declining amounts for up to 8 days after primary exposure.

Serum neutralizing antibody showed a transient rise to Coxsackie virus, reaching a peak at 14 days and declining below demonstrable titres by 28 days after exposure. The antibody titres attained were proportional to the dose of virus administered and the degree of neutralization was very similar to both SVD and Cx B5 viruses.

On cross challenge by exposure to SVD virus 28 days after exposure to Cx B5 virus, most animals (5/6) succumbed with typical vesicular lesions, although the serum neutralizing antibody titres showed a characteristically anamnestic response to both viruses.

The levels of cytopathic enteroviruses at two wastewater-treatment works were monitored over a period of 9 months. The maximum level of virus at works 1 was 72500 p.f.u. l-1 and at Avorks 2,57500 p.f.u. l-1. Examination of process efficiency showed an overall reduction of 63% for works 1 and 26 % for works 2 when used without lagooning. When lagooning was employed at the second works, virus reduction was 97%. Individual treatment processes showed poor reduction of virus levels. Sedimentation and rapid sand filtration had no significant effect on levels whilst both percolating filtration and activated sludge showed some reduction. Only lagooning resulted in substantial reductions of virus levels.

Childhood varicella vaccination has not yet been introduced in the UK. To inform decision-making about future vaccine programmes, data on the burden of varicella in general practice over a 10-year period (01/01/2005–31/12/2014) was calculated by age and ethnicity, using anonymised data from >8 million individuals in the Clinical Practice Research Datalink. Varicella consultations peaked at 20 603 in 2007, then decreased annually in all age groups to 11 243 in 2014. Each year, consultation rates were common among infants, were highest among 1–3 year olds (61·2 consultations/1000 person-years in 2007, 39·7/1000 person-years in 2014) and then fell with increasing age to <1·0/1000 person-years at ages ⩾20 years. Varicella acquisition appeared to be delayed in some ethnic groups, with lower consultation rates for children aged <3 years but increased rates for older children and adults aged ⩽40 years among those of black African, Afro-Caribbean, South Asian or other Asian ethnicity. Decreasing general practice consultation rates over time could reflect changes in healthcare utilisation, with patients seeking care in alternative settings such as Accident and Emergency Departments, although current data prevent full assessment of this. Availability of data on varicella diagnoses across all health settings would enable estimation of the total healthcare burden due to varicella and the cost-effectiveness of introducing varicella vaccination.

A retrospective cohort study was conducted to identify risk factors for bovine tuberculosis (bTB) recurrence in New Zealand cattle and deer herds identified as bTB-infected from 1 June 2006 to 1 November 2010. A Cox proportional hazards model identified a positive relationship between the daily hazard of bTB recurrence and: (1) the number of prior bTB episodes for two episodes [hazard ratio (HR) 3·22, 95% confidence interval (CI) 1·21–8·60], and for five episodes (HR 89·5, 95% CI 13·8–580), (2) more than one positive bTB case animal at the index episode (HR 2·25, 95% CI 1·19–4·25) and (3) the presence of cleared test-positives at the final test of the index episode. The proportional hazards assumption was violated for the latter variable so a time-dependent covariate was introduced. Up to 2 years post-clearance, the daily hazard of bTB recurrence was greater in herds with test-positives at the final test (HR 2·59, 95% CI 1·30–5·13), but this effect was not observed more than 2 years' post-clearance (HR 1·05, 95% CI 0·28–3·91). We conclude that unresolved infection contributes to further bTB episodes in the first 2 years after herd clearance.

1. An experiment on the feeding of calves is described, which lasted over 2 years, and which was carried out on a healthy Shorthorn herd free from tuberculosis and contagious abortion.

2. Alternate animals as they were born were allocated, without any selection whatever, to one or other of two groups. One of these was fed on raw, the other on pasteurized milk. Every animal received its mother's colostrum for 3 days before being put on the milk diet.

3. The milk used was taken from the mixed morning's milk of the whole herd. It was divided into two parts, one of which was given raw, the other of which was submitted to low-temperature pasteurization at 145° F. (628° C.) for 30 nun, and subsequently cooled. The animals were fed morning and evening on measured quantities that were in strict relationship to their body weight.

4. In addition to the milk, hay was allowed ad lib. Observations showed that practically none was eaten during the first month, after which each animal consumed about 1 lb. a day, rising to 3 lb. by the eighth week.

5. With the exception of two weaklings which died after 15 and 23 days respectively from causes apparently unconnected with the nature of their diet, all the animals—twenty-five in the raw and twenty-three in the pasteurized group—throve well, and showed no obvious signs of rickets or anaemia.

6. The average increase in weight over the 8-week period for the animals in the raw group was 53·72 lb., and in the pasteurized group 53·86 lb., or 61·18 and 62·94 per cent respectively. This practical identity in weight increase is all the more surprising in view of the fact that the number of bull calves was very much less in the pasteurized than in the raw group.

7. The highest individual gain among the bull calves—one of 80 lb.—and the highest individual gain among the heifer calves—one of 63 lb.—both occurred in animals fed on pasteurized milk.

8. At no time throughout the experiment was any observer, lay or professional, able to distinguish between the two groups of animals.

9. The diet given, though permitting of good skeletal development, was insufficient to fatten the animals. After they had been transferred, however, to a normal diet at the conclusion of their 8 weeks in the experiment, they soon put on weight and within 2 or 3 months were indistinguishable in size or condition from animals that had received a more generous diet from birth.

10. There is nothing in these results to suggest that the nutritive value of pasteurized milk for calves is in any way inferior to that of raw milk.

New variants of Vibrio cholerae O1 have appeared in different time-frames in various endemic regions, especially in Asia and Africa. Sixty-nine strains of V. cholerae O1 isolated in Zambia between 1996 and 2004 were investigated by various genotypic techniques to determine the lineage of virulence signatures and clonality. All strains were positive for Vibrio seventh pandemic Islands (VSP)-I and VSP-II and repeat toxin (RTX) gene clusters attesting their El Tor lineage. Interestingly, strains isolated in recent times (2003–2004) were identified as an altered variant (El Tor biotype that harbours El Tor type rstR but produce classical ctxB) that replaced completely the progenitor El Tor strains prevalent in 1996–1997. Recent altered variant strains differed from prototype El Tor strains isolated earlier in that these strains lacked two ORFs, VC0493 and VC0498, in the VSP-II region. PFGE analysis revealed two major clonal lineages in the strains; cluster A represented the strains isolated before 2003 and cluster B the altered strains isolated in 2003–2004. Cluster A was closely related to prototype El Tor reference strain isolated in Bangladesh in 1971. Cluster B was found to be matched with Bangladeshi altered strains but was different from the hybrid strains isolated from Mozambique and Bangladesh. This report provides important information on the genesis of altered strains of V. cholerae O1 isolated in Zambia and emphasizes the need for further studies to follow the trends of evolutionary changes.

Four thousand two hundred and thirty-five sera from 2794 patients and 740 sera from 735 tourists domiciled in Scotland recently returned from abroad were examined between 1977 and 1981 for antibodies to Legionella pneumophila and related organisms. In addition, specimens were examined from some patients for cultural or serological demonstration of these organisms in lung or sputum. One hundred and ten cases were diagnosed, 104 serologically, five by immunofluorescence demonstration of legionellas in lung biopsy or autopsy specimens and L. pneumophila serogroup 1 was isolated from a further case. Of patients with pneumonia 6·7% showed evidence of legionella infection. Only 0·4% of healthy tourists had antibodies at a level of ⋝ 256. The majority of cases occurred in patients aged 50–69 and in 36 patients the infection was acquired outside the United Kingdom. Males predominated, the male: female ratio being 2:1. Cases were less frequent in the first quarter of the year but those originating in Scotland were equally common in the remaining three quarters. Cases with disease acquired abroad added to indigenous cases resulted in a summer peak occurring in July, August and September. There were no outbreaks of legionellosis in Scotland.

Pertussis is an infectious respiratory disease for which mass vaccination is an effective preventive strategy. In many developed countries, where high vaccination coverage has been maintained for approximately 50 years, re-emergence of the disease has been observed in all age groups. In the municipality of Rio de Janeiro (RJ), where vaccination started in the 1980s, surveillance data show no sign of disease re-emergence. We developed a mathematical model that incorporates the major demographic aspects of a large urban centre in a developing nation, in addition to the most important epidemiological aspects of disease transmission. Parameter values were estimated based on RJ demographic and vaccine coverage data. Overall, all vaccination strategies determined a major decrease (over 95% decrease when compared to the pre-vaccine era) in the incidence of primary infections (occurring in individuals who have never been immunized through infection or vaccine). On the other hand, the strategies (a) three doses at age 2–11 months, (b) three doses plus booster at age 12–23 months, (c) three doses plus booster at age 4–5 years, and (d) three doses plus both boosters, differently affected the incidence of secondary infections (occurring in previously infected/vaccinated individuals). Given that the immunity against pertussis wanes with time and that the infectious agent has not been eliminated from the population, it is expected that pertussis will continue to be a problem in RJ. Actually, since immunity acquired from vaccine wanes faster than disease-acquired immunity and the possibility of natural boosters has decreased with mass vaccination, an increase in the incidence of secondary infections among older age groups is expected (and predicted by the model). Possible explanations as to why this dynamics is not captured by the RJ surveillance system are discussed. A poorly effective surveillance system and a lack of awareness regarding loss of immunity and the possibility of pertussis infection in older age groups are among them. Finally, we bring attention to the need of (i) field studies for the measurement of pertussis incidence in adolescents and adults; (ii) better understanding of the transmission dynamics currently occurring in RJ, and (iii) re-evaluation of vaccination strategies with the possible introduction of acellular vaccines for the vaccination of older individuals.

The relationship between visual inspection ratings given to ten food retail premises and the microbiological quality of food samples was examined. Viable counts of bacteria and of Staphylococcus aureus were determined for cooked meat samples from each of the premises. There was no correlation between potential risk of foodborne infection, as assessed by total inspection rating, and bacteriological counts in food (P < 0·05). Neither was there a consistent relationship between scores given to any component of the total rating and the bacteriological quality of food.

The effectiveness of the current UK inspection scheme in assessing risk of foodborne infection is questioned. Inclusion of appropriately weighted criteria such as food temperature abuse is suggested to improve the scheme.

A radial haemolysis test designed to detect antibody specifically directed against the neuraminidase is described and compared with currently available techniques for the routine diagnosis of infection with influenza viruses.

Paired sera were available from two outbreaks of influenza A, one with the N1N1 subtype and the other with the H3N2 subtype. This technique confirmed diagnosis in 92% of cases diagnosed by other laboratory methods.

A series of meatal swabs, taken from 17 men over a period of 17 months during their tour at an Antarctic base was examined for mycoplasmas. The number of organisms isolated never exceeded 104 and not every specimen from each man yielded mycoplasmas. Nevertheless, Mycoplasma hominis was isolated from 71% and T-mycoplasmas from 59% of the men at some time during their stay. M. hominis persisted in the presence of serum IHA antibody titres of 1/64. Three subjects yielded only M. hominis and one only T-mycoplasmas.

Six men had already spent a year at the base when the study began and myco-plasmas were still being isolated from some of them at the end of a 31 month period of isolation. The persistence of mycoplasmas in the male genital tract can therefore be independent of sexual contact. Two modes of persistence are suggested; either a few men act as carriers and reinfect the others by contaminating their environment, or as seems more likely, most men have chronic infections.

A study was made of the ‘latent’ viral flora of simian tonsils. This was followed by isolation of viruses from two batches of sick monkeys whose illness is described. Simian viruses 15, 17 and 32 were isolated from nose and throat swabs obtained from the sick monkeys. A connexion between human and simian adenoviruses is suggested.