Foot-and-mouth disease virus of type O (strain Israel 1/63) was passaged serially fourteen times in cattle previously vaccinated with increasing doses of formol-treated vaccine of the homologous strain. Primary and secondary lesions developed in the majority of the animals. Virus from the 14th passage, which proved to be capable of reinfecting animals only 34 and 35 days after infection with the original strain, differed from the original strain in complement-fixing properties and in sensitivity to antiserum. These changes were of a degree indicative of subtype variation.

Virus titres in the saliva, in the tongue vesicles and in the foot vesicles of partly resistant cattle were very great and would have constituted a danger to other stock under field conditions.

The experimental data confirm previous observations on the infection of partly resistant cattle and on the isolation of variant strains during passage of FMD virus in tissue cultures containing specific antiserum.

The incidence of positive toxoplasmin skin test among subnormals in hospital was compared with that in subnormals attending day training centres and among normal children taken into County Council children's homes. Twelve out of 120 subnormals below the age of 20 attending day training centres were positive to the test, and 23 were positive out of 233 subnormals of the same age tested in hospital.

There was only 1 positive out of 71 children under the age of 18 in the County Council children's homes, compared with 29 out of 296 subnormals of this age who were tested.

The incidence of positive skin test among 115 mongols under the age of 50 was about 11% in each age range, whereas that in 709 other subnormals rose from 5% in those below the age of 10 to 30% in those over the age of 30.

Although factors similar to those causing admission of normal children to County Council care often determine the admission of subnormals to hospital, the children in County Council homes did not share the high incidence of infection which was found in subnormals.

It is suggested that the majority of infections among subnormal children are postnatally acquired. Since the incidence was the same in subnormals living at home as among those in hospital it is suggested that some personal habit commoner among subnormal than among normal children exposes the subnormals to an increased risk of infection.

An epidemiological survey of salmonella infection in a closed herd of pigs is reported. The main cause of cross-infection resulted from the movement of animals, with subsequent mixing of infected and clean stock and exposure of non-infected animals to infected faeces. Pen-to-pen infection carried by farm attendants also proved important.

An extended survey is at present being conducted to gain further information on the processes of cross-infection.

FMDV strains were titrated in pigs by inoculation of the bulb of the heel of the foot, the coronary band region of the foot, and the tongue. Heel inoculation gave end-points approximately 300-fold higher than did the other two methods.

Parallel titrations in cattle and mice gave infectivity estimates approximately 10-fold and 100-fold higher, respectively, than did heel titration of pigs.

The average variance of individual end-points determined for heel titration was 0·46 (log10 units) and that determined for coronary-band titration was 0·74. The sources of variations in end-points given by heel titrations are discussed.

The relationship between chickenpox and yaws epidemics occurring among children in a village in Netherlands New Guinea is analysed using the mathematical model for a simple deterministic epidemic. It is shown that the yaws epidemic accelerated significantly in the month following the chickenpox epidemic, but that it reverted to its previous rate in the succeeding months. The number of yaws cases attributable to the influence of the chickenpox is estimated from the projected course of the yaws epidemic. It is statistically verified that those children contracting chickenpox were more likely to become yaws cases in the subsequent month.

These results point to the danger of yaws's spread being much more rapid among a population which has recently been subject to an epidemic of chickenpox.

Sera from 3163 patients were examined for growth-inhibiting and complement-fixing antibody to Mycoplasma hominis. The results were analysed in respect of the age and sex of the patients. Antibodies were found to be uncommon in young people but increased in frequency with age; they were present in old men but were less common in women over sixty-five. Patients attending V.D. clinics and prison inmates had a much higher incidence of antibody than hospital and ante-natal patients. Complement-fixing antibody was approximately three times as common as growth-inhibiting antibody in the sample examined; it was also more common in women than men but the overall incidence of growth-inhibiting antibody was the same in each sex. It was concluded that possibly growth-inhibiting antibody is produced in more severe infections and that it disappears from the serum more quickly than complement-fixing antibody.

1. Coxsackie A6 virus was isolated in January 1963 from the circulating blood of four children in Suva, Fiji, suffering from fever, lymphadenitis and pharyngitis.

2. Nine strains of the same agent were isolated from Aedes (Stegomyia) poly-nesiensis mosquitoes caught over a period of 2 weeks near or in a village situated among mangrove swamps at the mouth of the Rewa river, in January 1963.

3. No virus was isolated from mosquitoes caught in Suva.

4. A serological survey indicated that Coxsackie A6 infections are common and widespread in Fiji.

Previous estimates of the incidence of glandular fever vary widely. Reasons for this are suggested. The present investigation was designed to show the incidence of cases of glandular fever presenting to doctors in certain general communities near Portsmouth in 1962–63.

The overall incidence in these areas during the year was found to be 38 per 100,000 population; this amounts to an average of one case annually in a medium-sized general practice. The incidence appeared to be lowest in a council housing estate. Glandular fever was not common in children, although it was frequently diagnosed on clinical grounds.

The ways in which cases of glandular fever might be missed in a survey such as the present one are discussed. It is thought that many patients may become ill but not consult their doctors. Truly subclinical glandular fever, however, is thought to be infrequent.

A high incidence of drug resistance, mostly of the infective type, was found amongst strains of Escherichia coli isolated from human beings suffering from neonatal diarrhoea, calves and lambs suffering from neonatal diarrhoea or bacteraemia, pigs suffering from neonatal or post-weaning diarrhoea or bowel oedema and from fowls suffering from ‘coli-septicaemia’. The strains from the human beings, pigs and fowls, and those from calves and lambs suffering from bacteraemia, belonged to serotypes generally accepted as being pathogenic for these species.

Complex drug-resistance patterns were a common feature, particularly amongst the human and calf strains, some being resistant to six drugs. Only two drugs, polymyixin and nalidixic acid, were active on all the strains.

The incidence of drug resistance amongst pig strains was twice as great in those isolated in 1965 as in those isolated in 1960–62; neomycin and furazolidone resistance was found amongst the 1965 strains but not amongst the 1960–62 strains.

Infective resistance was easily demonstrated; tetracycline resistance was transferred from one tetracycline-resistant strain of E. coli to 37 of 38 tetracycline-sensitive strains at the first attempt.

Most ampicillin, streptomycin, tetracycline, chloramphenicol, neomycin and sulphonamide resistance was of the infective type; the furazolidone resistance in all of eight strains studied was not shown to be infective.

In the experiments to demonstrate the presence of infective resistance the level of drug resistance was usually found to be the same in donor and recipient strains.

Reactions to the pertussis component of the original commercial batches of quadruple vaccine against poliomyelitis, diphtheria, tetanus and pertussis (Quadrilin, Glaxo Laboratories) gave some cause for concern. Severe reactions were found to be more common in infants under 6 months of age than in older infants.

A modified quadruple vaccine, which has been used in N. Ireland since October 1964, was found to give rise to significantly fewer and milder reactions. This vaccine when given in three doses separated by intervals of 6–9 weeks and 6 months to fifty-eight infants most of whom were 6–7 months of age at the start of immunization was found to give a satisfactory immunological response.

The efficiency of a diphtheria, tetanus, poliomyelitis vaccine in inducing a serological response after a three-dose primary course of immunization was tested in thirty-nine children aged 5 and 6 years and found to be satisfactory. This vaccine had previously been shown to be suitable for use as a single dose reinforcing vaccine for children of this age who had been immunized in infancy. It is suggested that all children might receive one dose of the vaccine at the time they enter school, and then those who have not been immunized before should receive a further two suitably spaced doses to complete their course of primary immunization.

Five healthy young women swam in untreated water of known bacterial quality under a variety of hygienic conditions. Evidence based on bacteriological examination of water samples leads to the following conclusions:

1. There is a marked variation in the number and types of bacteria shed by a bather while swimming and the variations do not seem to be correlated to the differences in personal hygiene or the menstrual period.

2. Faecal organisms may be discharged in considerable numbers by a swimmer after a thorough and careful shower with soap and warm water and yet not be discharged in appreciable numbers by a bather who does not take a shower before swimming.

3. Faecal organisms constitute only a small minority of the total number of viable bacteria that are discharged in swimming pool water by a bather during the act of swimming and as such seem to have limited use as indicators of total bacterial pollution.

4. Members of the genus Staphylococcus are shed in large numbers under all conditions and Staph. aureus is consistently present. Therefore, this genus appears to be a good choice as an index for the determination of body contamination.

5. Further studies are indicated under more stringently controlled hygienic conditions to determine the value of hexachlorophene in reducing microbial flora that a given individual may shed during swimming.

The twenty-four young women and one man treated in an ultra-clean isolation ward should have had a low incidence of staphylococcal infection on grounds of age, sex and clean environment alone. However, they apparently acquired new strains of Staph. aureus at the rate of 4·7/100 patient weeks (3·9 multiple resistant strains/100 patient weeks) from the sixth week after admission onwards.

Environmental factors contributing to infection included introduction of resistant strains by the patients on admission, contact between patients in the unit, and failure to eliminate nasal carriage in staff and patients.

Host susceptibility was increased by malignancy, and by antibiotic and cytotoxic therapy. The nasal carriage rate of Staph. aureus was significantly greater for patients with repeated episodes of leucopenia induced by cytotoxic drugs.

Parallel titrations of a strain of trachoma (MRC–221) and one of inclusion conjunctivitis (MRC–4) in the baboon conjunctiva and in chick embryos suggest that ten to twenty 50% egg infective doses are equivalent to one 50% baboon infective dose; but that at least 1000 egg infective doses are needed to induce moderate or severe infections in all of a given number of baboons.

For vaccine experiments in baboons, a system of scoring physical signs and presence of inclusion bodies was devised; the significance of differences in vaccinated and control animals in their response to conjunctival challenge was determined by analysis of variance. An aqueous suspension of live MRC–4 grown in the yolk sac was given as two subcutaneous doses and one intravenous dose at weekly intervals, and protected all of six baboons challenged with the homologous strain; three similarly spaced subcutaneous doses were less effective. The immunity induced by this vaccine waned considerably during the ensuing 15 months. Vaccine prepared from a live ‘fast-killing’ variant of MRC–4 grown in HeLa cells was less effective than MRC–4 itself in protecting baboons against infection with the parent strain.

Although both yolk sac and HeLa cell vaccines induced the formation of antibody fixing complement with trachoma group antigen, the serum titres in individual animals at the time of challenge were unrelated to the degree of protection; during a 15 month observation period there were pronounced falls in the titres of antibody induced either by vaccination or by challenge with egg-grown TRIC agent.

We wish to thank Dr I. Sutherland (M.R.C. Statistical Research Unit) for his helpful advice during the early stages of this work. We are also greatly indebted to Mr P. Avis (Pfizer Ltd.) for his advice and for undertaking the statistical computations; and to Miss Anne Smith and Miss Pay Storey (M.R.C. Trachoma Research Unit) for doing the complement fixation tests.

A mineral oil adjuvant failed to enhance or to prolong the somewhat shortlived immunity induced in baboons by trachoma/inclusion conjunctivitis (TRIC) vaccines, and was of little or no value in increasing or prolonging the formation of group complement-fixing (CF) antibody. Vaccines prepared with protamine sulphate or with calcium phosphate were no more immunogenic than the untreated parent suspensions.

Cross tests with aqueous vaccines revealed antigenic differences in the TRIC agents examined, in terms of their ability to protect against conjunctival challenge. Strain MRC–1/OT differed from MRC–17 and from MRC–4, and MRC–187 from MRC–4f.

The four Gambian trachoma agents tested were much less effective than the MRC–4 strain of inclusion conjunctivitis in inducing group CF antibody in baboons. The titre of circulating antibody bore no relation to the state of immunity to conjunctival challenge.

In three baboons given mineral oil adjuvant vaccine and in one given aqueous vaccine the conjunctival responses to subsequent challenge were significantly enhanced. This reaction may be an expression of a hypersensitive state induced by relatively ineffective vaccines; like immunity, it is unrelated to the titre of CF antibody in the serum.