Samples of yellow-fever vaccine prepared from homogenized chick embryos, and of an experimental measles vaccine prepared from chick embryo cells, have each been shown to contain a contaminant virus similar in properties to an avian leukosis virus. Young adult males injected with the yellow-fever vaccine did not develop neutralizing antibodies for Rous sarcoma virus.

During 9 months the author observed 309 cases of infection with Salmonella enteritidis, of which 88% were hospital infections in six childrens' wards of three different hospitals. The foci were connected epidemiologically. In 97·7% of those examined, the bacteria were detected in faeces, in 68% in urine and in 27·5% in the upper respiratory tract. Bacteraemia was found in 17·2%. The bacteria were also detected in two air-samples and in two swabs from linen and furniture. All isolated strains were highly resistant to antibiotics and to drying, but sensitive to the action of chloramine. In infected patients with parenteral localization of bacteria, the agglutination test with specific gm antigen was positive in 80% of cases. Many patients were persistent carriers for 5–10 months. In adults a short faecal carrier state was usually observed. The epidemic spread by contact, though in some cases it was probably air-borne. Such epidemics are very difficult to bring to an end.

A study was made of the development of skin resistance and delayed hyper-sensitivity to vaccinia virus after immunization with inactivated vaccinia virus in rabbits. These vaccines are shown to increase skin resistance, and it is also shown that the development of this resistance is dependent upon the virus content of the vaccine. Skin resistance is shown to be related to the titre of circulating antibody rather than to the degree of delayed hypersensitivity. Possible reasons for conflicting reports in the literature on this subject are discussed.

An unusual skin reaction was seen in some animals when challenged with live virus after immunization with inactivated vaccine. The nature of these reactions is discussed.

The neutralization of a constant dose of Semliki Forest virus by various doses of different antisera was studied. The presence of complement (1/200, v/v) in the neutralization mixture inhibited the neutralization by high concentration of antiserum and somewhat potentiated neutralization by low serum concentration. Because the experiments were biased towards a measure of irreversible neutralization, the inhibition observed in the presence of complement appeared to be an inhibition of irreversible neutralization. This inhibition was interpreted as a dissociation of a complement binding virus–antibody complex. The antibodies involved appeared to be virus-specific.

Modern contact insecticides (like DDT) in powder form are ideal for combating widespread lousiness; but for various reasons they are not suitable for disinfecting small numbers of infested people under civilized conditions. It appears that the most convenient, efficient method in these circumstances is a small-scale fumigation of the infested garments, in either a metal bin or a plastic bag. Ethyl formate, one of the liquid fumigants suggested for this purpose by W. A. L. David in 1944, has been further tested and found efficient. In a plastic bag the size of a potato sack (about 30 × 40 in.), four blankets can be deloused by a dose of 100 ml. with an hour's exposure or a quarter of this dose with an exposure of 5 hr. or more. An overnight treatment with this dose would be safe and convenient, costing about Is. and the actual operations would take only a few minutes.

During the summer and autumn of 1964, echovirus 4 was found widely distributed in northern Japan; this virus was associated with localized outbreaks of iaseptic meningitis in many regions. The evidence that the echovirus was aetio-logically related to aseptic meningitis was shown by the virus isolation from cerebrospinal fluids and faeces and the serodiagnosis of paired sera in many patients: Age-specific sero-immunity and morbidity rate suggested that echovirus 4 had spread extensively in about 1954. The strains of echovirus 4 isolated in the 1964; epidemic were similar to the prototype strain, Pesascek, in biological characteristics.

The incidence of heat-resistant Cl. welchii in selected classes of a rural population has been investigated. The carrier rate for the general population was low (l·5–6·0%), but persons associated with communal feeding and poor hygienic conditions were shown to have a much higher carrier rate (15·1–25%).

Sex and season had little effect on the incidence of the organism, but among aboriginals the carriage was significantly affected by age. This was probably due to eating habits of the different age groups. The carriage appears to be transient; no persons were shown to be permanent carriers of one strain of heat-resistant Cl. welchii.

Sera from healthy Greeks, Liberians and East Africans were tested for dye test and direct agglutinating toxoplasma antibodies. At a titre of 1/16 or more 137/228 Greeks, 84/133 Liberians, 2/13 Bondei infants, 3/7 Bondei adults, 3/9 Masai infants and 20/43 Baganda adults gave a dye test positive result. This confirms the wide-spread occurrence of this infection.

Cattle infected with FMDV strains of different epizootiological origin developed a carrier state which persisted in the majority of animals for several months. Fluid samples taken from the oesophageal/pharyngeal region were assayed for infectivity by plaque counts on BHK monolayer cultures and by mouse inoculation. With one strain of virus, infectivity levels of up to 1000 pfu/ml. were recorded for several weeks after infection but in general the virus content of samples was below 50 pfu/ml.

The sites of virus persistence and multiplication were identified by titration of suspensions of mucosae and epithelia taken post mortem. Virus was recovered from 41 of 54 cattle killed 14–196 days after infection. The chief sites of virus multiplication based on the frequency of virus recovery and infectivity titres were the dorsal surface of the soft palate and the pharynx. Virus was recovered less frequently from the ventral surface of the soft palate and the glosso-epiglottic space and only occasionally from the tonsillar sinuses, tonsils, tongue, trachea and oesophagus. No virus was detected in the turbinates or in the epithelium of the urinary bladder.

A fermentation-inhibition test for the measurement of growth-inhibiting anti-body to acid-producing mycoplasmas was performed in microtitre plastic plates. M. pneumoniae, M. fermentans and the Negroni agent were selected for study. Antibody could be titrated since specific antiserum inhibited mycoplasma growth and the concomitant production of acid, thus preventing a change in colour of phenol red which was incorporated in the growth medium. It was essential to use unheated horse serum as a component of the growth medium. The inhibitory effect of specific antiserum was much decreased when the horse serum was heat-inacti-vated, indicating the need for a heat-labile accessory factor. The additional use of unheated guinea-pig serum was essential for demonstrating the growth-inhibiting effect of specific antiserum on the Negroni agent. The test was reproducible, specific and sensitive. Sixteen-fold or greater antibody rises were demonstrated in paired sera from volunteers infected with M. pneumoniae. Tests with ninety-five random adult sera showed that 22% had antibody to M. pneumoniae at a titre of 1/5 or more and 13–5% had antibody to M. fermentans.

Quadruple vaccine containing 75 D antigen units of killed type 1 poliovirus was given to children at ages 2, 3 and 4 months followed by a booster dose at 15 months.

The serological response to the primary course was difficult to assess owing to maternal antibody. Antibody titres to the type 1 component after the booster dose were very satisfactory and about 10 times higher than those observed in a similar group of children given attenuated vaccine. Response to the poliovirus types 2 and 3 in the quadruple vaccine was less satisfactory.

Graded doses of attenuated poliovirus type 1 were fed to the children 2 months after the primary course and 1 month after the booster dose. Children who had received no poliovaccine and children immunized with attenuated vaccine were included for comparison.

Immunization with killed vaccine did not greatly affect the size of the minimal infecting dose of live virus but reduced both the duration of the subsequent infection and the titre of virus in the faeces.

The epidemiological significance of these findings is discussed.

1. A small but serious outbreak of Ps. aeruginosa infection in a premature baby ward has been described.

2. Heavy contamination of the suction apparatus and tubing was demonstrated to be the main reservoir of infection.

3. It was also shown that this apparatus could disseminate the organism as an aerosol.

4. The measures adopted to eliminate the source and prevent dissemination of the infectious agent have been described.