Ten laboratories collaborated in a study of minimum immune titre (MIT) of rubella haemagglutination-inhibiting (HI) antibody with one laboratory acting as a reference laboratory to provide a uniform basis for comparison of the HI results. The international unitage equivalent to the MIT used by the ten laboratories was found to vary from 24 to 98 units. Testing of the sera by immunofluorescence and by HI after flotation centrifugation indicated that residual non-specific inhibitors may interfere with HI antibody testing to an extent equivalent to 12–15 units. An acceptable MIT would therefore be equivalent to 24–48 units of rubella HI antibody. The single radial haemolysis (SRH) results on the sera indicate that this is a sensitive and specific test for rubella antibody.

During the first year of a study of respiratory disease in the semi-isolated community of Port Chalmers, New Zealand, an epidemic of clinical influenza occurred from which the variant influenza A/Port Chalmers/1/73 (H3N2) was isolated. Within a selected group of 26 families, 59 (46%) members had clinical or laboratory evidence of infection. During intrafamilial spread the infection frequency was highest for school-aged children (77%), followed by female adults (67%), infants (64%) and male adults (41%). The index infection in each family was a school-age child on 10 occasions, suggesting the role of this age group in the transmission of influenza A in this community. The secondary attack rate (SAR) of 58·3% was higher than expected.

In sera taken before the 1973 epidemic, 59% of family members had detectable HI antibody and 25% NI antibody to A/England/42/72 while 38% had detectable HI antibody and 8% NI antibody to A/Port Chalmers/ 1/73. The relation between pre-existing antibody and infection frequency is discussed.

Coxsackievirus B5 in the presence of fetal calf serum was exposed to six commonly used disinfectants for times of 10, 20 and 30 s. At the end of exposure times skim milk neutralized the disinfectant activity, with residual virus assayed by the plaque technique. The six disinfectants considered were Javex, sodium hydroxide, ethanol, Wescodyne, One Stroke Ves-Phene and Sonacide. Although 95% (v/v) ethanol was significantly more virucidal than dilutions of the other five disinfectants tested causing a 106 reduction in 20 s, it may not be practical to use in many instances. Next to 95% (v/v) ethanol, 1/75 (800 parts/b6) Javex, 0·25% (w7/v) sodium hydroxide and 1/200 Wescodyne were the most effective virucides. These disinfectants were equal in effectiveness causing a 105 reduction of coxsackievirus B5 in 30 s. Of these three disinfectants Javex is the most practical to use since sodium hydroxide is caustic and Wescodyne is selective in its virucidal action. Undiluted Sonacide was a less effective virucide causing a less than 10-fold reduction of coxsackievirus B5 in 30 s. A 1/50 dilution of One Stroke Ves-Phene was the least effective virucide tested since it did not significantly inactivate coxsackievirus B5 in 30 s.

During a 7½ year period pneumococci were isolated from body fluids of 124 patients at the Radcliffe Infirmary, Oxford – 72 with pneumonia, 26 with meningitis and 26 with other serious infections. Eighty-one (65%) of the patients were over 50, and 33 (27%) were over 70 years old. Of the 124 pneumococcal strains 104 (84%), including 23 (79%) of those from patients who died, belonged to types included in the vaccines successfully used in South Africa and in Papua New Guinea. The relative frequencies of types in the Oxford series and in a larger British series agreed closely with those found in a recent survey of 3644 bacteraemic pneumococcal infections in 10 American cities. Any polyvalent pneumococcal vaccine licensed for use in the United States is thus likely to be relevant to the situation in Britain.

Echovirus 11 in the presence of fetal calf serum was exposed to six commonly used disinfectants for times of 10, 20 and 30 s. At the end of such exposure times, skim milk neutralized disinfectant activity and residual virus was assayed using the plaque technique. The six disinfectants studied were Javex, sodium hydroxide, ethanol, Wescodyne, One Stroke Ves-Phene, and Sonacide. Although 0·25% (w/v) sodium hydroxide and 95% (v/v) ethanol were equally virucidal and significantly more so than the other four disinfectants, causing 106 reduction in 20 s, they may not be practical to use in many instances. Javex at a dilution of 1/50 (1200 parts/106 chlorine) proved to be virucidal causing 103·5 reduction of echovirus 11 in 30 s. Wescodyne (1/50) and undiluted Sonacide were relatively ineffective causing 10 reduction or less of echovirus 11 in 30 s. One Stroke Ves-Phene (1/50) was ineffective causing no significant inactivation in 30 s.

Outbreaks of myxomatosis during the winter or spring have coincided with the establishment of the European rabbit flea in the Mallee region. The severity of these outbreaks has varied from causing complete suppression of the normal spring increase in rabbit numbers to being completely ineffective in a year in which late spring rains allowed rabbit breeding to extend into the early summer.

In 1973 and 1974 effective spring myxomatosis caused heavy mortality in kittens before they emerged from the warrens. The age of the population increased as the result of few young rabbits coming into the population and of the lessened stress on old rabbits in a low summer-autumn population. This effect was reversed in the late-breeding year, 1976, when flea numbers were apparently too low to maintain a spring outbreak and rabbit numbers increased rapidly.

Sharp reductions in the wild rabbit (Oryctolagus cuniculus (L.)) population in the Mallee are associated with annual myxomatosis epizootics. The extent to which the population reductionsare the direct result of the epizootics varies with time of epizootic occurrence. All grazing animals in the Mallee are under nutritional stress each summer and autumn. When the epizootic occurs during the early summer heavy losses occur in a previously healthy population. Similar losses which occur in the late summer and autumn are the result of a nutritional stress – epizootic complex. The end result in each case is a population reduction of about 80%.

This reduction occurs in a population which is the most resistant to myxomatosis known in Victoria and in association with epizooties caused by field strains of myxoma virus of moderate virulence only.

The earlier summer epizootics are of considerable economic importance because they sharply reduce the pressure on the limited food available for other grazing animals.

Three hundred and twenty-two strains of Bacteroides fragilis isolated from infected patients at three different hospitals were tested against 20 type specific B. fragilis antisera using the tube agglutination technique. Of these strains 41·3% were assigned to a single O-serotype, a further 20·5% were agglutinated by several antisera and could not be classified and the remainder showed no reactions. Three different serotypes were prevalent in the three hospitals and minor geographical variation was observed.

No correlation was found between serotypes and the origin of infection, but those from the blood were the most readily typable strains. No correlation was found between serotypes and biotypes of B. fragilis.

In a study of the distribution of e-antigen and anti-e in subjects whose blood was positive for hepatitis B surface antigen (HBsAg), patients with acute hepatitis B who were tested during the incubation period were all e-antigen-positive but after the onset of illness e-antigen was detected in only 11%. Persistence, and in some instances reappearance of e-antigen in those who became long-term carriers of HBsAg was associated with high titres of HBsAg. There was a high incidence of e-antigen in those conditions in which cell-mediated immunity may be depressed, including Down's syndrome and chronic renal failure.

The majority of HBsAg carriers identified as sources of infection were e-antigen-positive. A positive reaction for e-antigen is evidently associated with a defective immune response to hepatitis B virus infection which permits continued replication of virus in liver cells accompanied by high titres of HBsAg, numerous Dane particles and detectable DNA polymerase in the blood with consequently a greater likelihood of transmitting infection.

Although it cannot be assumed that anti-e positive carriers of HBsAg are not infective, it may be necessary, in the assessment of passive or active immunization for the control of hepatitis B, to take into account the e-antigen/antibody status of possible sources of infection.

The occurrence of antibody to myxoma virus in wild rabbits following epizootics is highest in the semi-arid north-west of Victoria and lowest in temperate southern Victoria. Occurrence ranges up to about 90% in the north-west and to about 70% in the south except on the Western Plains where epizootics are rare and antibody occurrence seldom exceeds 30%.

The establishment of the European rabbit flea may be changing the pattern of occurrence of antibody in the north-west by causing spring outbreaks of myxomatosis. It is suggested that the effects of the replacement of a simple recurring system of epizootic and breeding season several months apart by the occurrence of myxomatosis twice in the same year, once coincident with the breeding season, will be complex. The occurrence of detectable antibody may be less dependent on the infection rate and may be dependent to some extent on the relative timing of spring myxomatosis and the breeding season.

The virus growth in the pharyngeal area and the virus excretion in milk of susceptible and vaccinated dairy cows after intranasal instillation of foot-and-mouth disease (FMD) virus type O1 were examined. Ten vaccinated cows were purchased through a market. Of these, nine had delivered their first calf. The cows were inoculated 2–9 months after having received the last dose of vaccine. All vaccinated cows resisted the intranasal challenge. The virus multiplied in the pharyngeal area but, compared with two susceptible controls, to a limited extent. No clear relation was found between virus growth and the titre of circulating neutralizing antibody at the time of challenge.

Virus was first detected in milk samples of the susceptible cows when generalized FMD lesions had developed on day four; the excretion lasted for 3–4 days.

Up to 19 days after inoculation untreated milk of the vaccinated cows was examined for the presence of infectious FMD virus. Samples were inoculated onto cell cultures, fed to susceptible pigs and calves and injected intramuscularly and/or intradermolingually into susceptible steers. No infectious FMD virus could be detected, either in cell cultures or in susceptible animals. The animals did not develop neutralizing antibody against FMD virus and were subsequently shown to be fully susceptible to challenge. The results are discussed with particular reference to current problems regarding the export of milk products from countries where vaccination against FMD is practised to countries free of the disease.

Particles released into the air by wringing the hands together were collected in a slit sampler before and after washing with bar soap, with three surgical scrubs, and after rubbing them with a spirit-based lotion. The particles were identified, their number estimated, those that bore bacteria counted, and the bacteria themselves classified. It was found that there was a significant increase, averaging 17-fold, in the number of particles carrying viable bacteria released after washing with soap. The increase in bacterial dissemination was suppressed if a surgical scrub was used in place of soap, or when the lotion was used without washing. The number of skin squames released increased by 18-fold or more after washing with soap or a surgical scrub, but not after using the lotion. This suggests that a surgical scrub should be used more widely in clinical practice, and that a spirit-based hand lotion might with advantage become a partial substitute for handwashing, particularly in areas where handwashing is frequent and iatrogenic coagulasenegative staphylococcal infection common.

The distribution of antibody to Nairobi sheep disease in sheep and goats in Kenya was found to coincide closely with that of the tick, Rhipicephalus appendiculatus. The proportions of a population in an enzootic area with antibody was similar in the different age groups. No antibody to the virus was found in rodent sera and while some low titres were found in some wild ruminant sera, these were considered to be most likely cross reactions with antibody to related viruses.

A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination.

For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing (FMD) virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.

Feeding tests were carried out in the laboratory to obtain basic data on the susceptibility of wild Norway rats to difenacoum. The results were used to derive a standard test procedure for the identification of difenacoum resistance in warfarin-susceptible and resistant rats. Details are given of tests on rats from suspected difenacoum-resistant infestations on farms.

Nairobi sheep disease was seen principally upon movement of susceptible animals into the enzootic areas. This occurred most frequently for marketing purposes near the main centres of population. Other outbreaks followed local breakdowns in tick control measures. The disease did not occur in epizootic form during the period under consideration.

Nairobi sheep disease was isolated from pools of Rhipicephalus appendiculatus but not from many pools of other tick species. No virus was isolated from the blood or tissues of a range of wild ruminants and rodents.

Nasal swabs were taken from 492 babies born consecutively to residents of two South Wales towns soon after their discharge from maternity hospitals. Staphylococcus aureus was isolated from 352 babies (72%) and in 79 (22%) of these it was resistant to at least one antibiotic. By the time these babies were a year old the prevalence of both sensitive and resistant strains had fallen, so that only 12% still carried nasal staphylococci, but 64% of these organisms were then resistant to penicillin. Administration of penicillin to the baby seemed to be a more important factor in selecting resistant organisms than other antibiotics given to the baby, any antibiotic treatment to other members of the household, or discharge from hospital.

Eleven fabrics selected to provide a representative range of yarns and weaves have been examined microscopically and subjected to a series of tests. The observations were directed towards assessing the potential ability of each fabric to resist penetration by particles, such as skin scales, which might carry micro-organisms. The number, size and shape of pores penetrating through the material were estimated and the penetration of test dusts assessed in several ways. While, generally, the relative merits of the fabrics are similar whatever test or measurement is considered there are a number of significant exceptions which reflect peculiarities of the test system or of a fabric. Comparison with the results of dispersal experiments with volunteers wearing garments made of the fabrics is made in a following paper.

The pathogenicity for mice of two mutants of herpes simplex virus (type 1 and type 2), which fail to induce thymidine kinase, were compared with their respective parent strains. The mutants were much less virulent than the parents following either intracerebral or peripheral inoculation. The replication of the virus at the site of inoculation and its progression into the nervous system were studied. Following a very large inoculum in the ear, the type 1 mutant was found to establish a latent infection in the cervical dorsal root ganglia. Mice inoculated intracerebrally with small doses of the mutant viruses were solidly immune to challenge with lethal doses of the parent strain.

The effectiveness of a representative range of fabrics in restricting dispersal through them of dry skin-borne bacteria has been examined. The fabrics were tested made up into trousers which were worn by volunteers during standardized exercise in a test chamber operated within a unidirectional flow clean-air room. Under these conditions, with careful attention to sealing at ankles and waist, it was possible to estimate penetration as low as 0·3%. Penetrations as low as 1% were observed with some synthetic fabrics. These had a relatively high surface resistivity and developed significant electrostatic charges.

When the observed values for penetration were compared with the results of a series of measurements and tests made on the fabrics it was clear that the correlation between these values and the other results was in every case very close for all the five woven cotton or cotton terylene fabrics but that no measurement or test was capable of predicting the behaviour of all the other materials in dispersal experiments. The inherent variability of dispersal experiments seems to be very great. With a standard deviation of the approximately log-normal distribution of the experimental values as high as about 2 times the mean, it is necessary to carry out as many as 20 replicate experiments in order to differentiate with certainty between garments with a two-fold difference in penetration.