The hygiene and marketing of fresh cream in England and Wales was investigated by a working party of the Public Health Laboratory Service (PHLS) between 1 October 1968 and 31 July 1969. Thirty-one cream-producing dairies were visited and observations made in the light of the Code of Practice published by the Milk and Milk Products Technical Advisory Committee of the Ministry of Agriculture, Fisheries and Food, and the Scottish Home and Health Department. Suggestions are made in this report to strengthen the code.

A total of 5184 samples of fresh cream comprising 4385 heat-treated, 282 clotted and 517 untreated were examined. Details of production, age of the cream, distance and mode of distribution along the retail chain were available for most samples, and this history was, as far as possible, related to the laboratory findings. In the laboratory the samples were examined by the methylene blue test, colony count, conform and Escherichia coli I test and for pathogens. Staphylococcus aureus was grown from 59 out of 3417 samples of cream; 54 of these were from untreated cream. Phage typing indicated that a proportion of these strains were of animal, presumably bovine, origin. Other human pathogens isolated included one each of Salmonella typhimurium, Brucella abortus, E. coli type O126 and Clostridium welchii.

It appeared that heat-treated cream was much better, bacteriologically, than untreated; and that large dairies, in general, had better premises, more hygienic methods of preparation and the advantages of mechanical filling and capping of cartons; thus they offered the consumer a better product, bacteriologically, than some of the smaller dairies.

A statistical analysis of the results of the tests used showed the methylene blue test, in spite of some anomalies, to be of more use as a screening test than any of the others. As this test is cheap and easy to carry out, the working party thought that it should be the test of choice. In view of the known anomalies, however, the working party recommends that the test should remain a screening or advisory test and have no penal function. Results should be reported as follows: cream not decolorizing the dye in 4 hr. at 37° C. (± 0·5°) after overnight incubation at 20° C. (± 0·5°) would be accepted as satisfactory; between ½ and 4 hr. at 37° C. (± 0·5°) as fairly satisfactory; but if the dye were decolorized at the end of the overnight incubation the sample would be provisionally classified as ‘unsatisfactory; requires further investigation’. A repeat sample would then be examined. If samples were repeatedly unsatisfactory, consultations would be arranged between the local authority, the laboratory and the dairy, with perhaps inspection of the dairy premises and retail storage conditions and further, more searching tests on samples made in an effort to eradicate production faults.

Pyocine typing was used for the characterization of 134 Pseudomonas aeruginosa strains isolated from bovine mastitis. The scheme of Gillies & Govan (1966) was adopted with some modifications, and the procedure gave 89·6% typability. Pyocine type 1 strains were most commonly encountered and were followed in frequency by types 10 and 3. The introduction of two additional indicator strains allowed for division of these types into subtypes.

In spite of some limitations, discussed in the paper, the pyocine typing scheme proved to be useful in ‘marking’ P. aeruginosa strains and in following their association with bovine mastitis in various herds.

The construction of a Regional Burns Centre in Pinderfields General Hospital, Wakefield, presented an opportunity to study Pseudomonas aeruginosa infection in patients with extensive burns. During the first year (Barclay & Dexter, 1968) a system of disinfection and bacteriological control created conditions permitting more detailed studies to be undertaken which resulted in a significant reduction of infection and cross-infection.

Thirteen men wintering on an Antarctic base were isolated from other human contact for 10 months. During this period Coxsackievirus A21 and later influenza A2 virus were administered to some of the men. Serum samples were collected from each of the men at monthly intervals.

Coxsackievirus A21 produced symptoms and apparently spread to uninoculated men. It also appears that repeated re-infections occurred and that the virus persisted in this small community for most of the period of isolation. HI antibody responses in the absence of neutralizing antibody responses seem to be transient.

The vaccine strain of influenza virus induced antibody responses but did not cause symptoms. There was no evidence of spread to uninoculated men.

Antibody titres against influenza C, parainfluenzaviruses 1 and 2 and coronavirus OC43 did not fall significantly during isolation.

An outbreak of respiratory illness occurred at the end of isolation and its origin was traced. No causative agent was detected.

The three heterologous anti-sera currently provided for tetanus prophylaxis have been compared with reference to the production of untoward reactions in 498 patients, and to the blood antitoxin concentrations produced in 76 patients. Equine serum, although giving rise to more reactions, was the only effective agent in terms of the levels and duration of serum antitoxin concentration produced. The local response to a test dose of any of the three sera is not a reliable guide to immediate or late general reactions.

Neutralization tests with a strain (BA) of Allerton-type herpes virus, derived from a buffalo (Syncenis caffer) were carried out on 924 sera from 17 species of E. African game animals and on cattle sera from Tanzania (2001), Kenya (792) and Uganda (410).

Buffalo populations throughout E. Africa showed a very high rate of infection, with all animals over 2 years of age serologically positive. Antibody was present in some giraffe, waterbuck and hippopotamus sera and, less frequently, in impala, eland, bushbuck and oryx. Data are provided on the titres of positive samples; the mean titre of buffalo sera increased with age.

Cattle in many localities of N. Tanzania and S. Kenya showed a very high rate of infection, 85–95% of sera from animals more than 2-years old containing antibody; the titres recorded were lower than those in buffaloes. Very high infection rates were also found in Karamoja and Teso (Uganda) and also in some other areas of Kenya, whilst a considerably lower incidence of infection was detected in W. Nile Province of Uganda and in central Tanzania. Differences in infection rates may have been related to herd size and husbandry practices.

It was shown that a wave of infection was probably spreading through cattle in N. Tanzania at about the same time as an outbreak of disease occurred in buffaloes and it is suggested that virus transmission may have been by biting flies.

No clinical signs attributable to the virus were reported in cattle but mouth lesions similar to those recorded in buffaloes, or nasal lesions, could have passed undetected. Allerton-type virus probably produces a range of clinical syndromes in cattle, closely resembling those associated with some herpes viruses in primates but infection is seldom related in the field to either pseudo-lumpy skin disease, mammillitis or stomatitis.

Organ cultures prepared from 15 different organs obtained from 43 fetuses were consistently found to support the growth of rubella virus, irrespective of the gestational age of the fetus or the strain of rubella virus inoculated. Although rubella virus replicated in fetal lenses, adult lenses did not support the growth of rubella virus. Organs obtained from four fetuses between 8 and 17 weeks gestational age produced similar titres of an inhibitor which had the characteristics of interferon. The use of Trowell T8 medium and incubation in a mixture of 5% CO2 in oxygen provided the most suitable conditions for the maintenance of most organ cultures. Under these circumstances it was possible to obtain adequate histological preparations from these organs, but light microscopy studies revealed no significant differences in sections of rubella inoculated and control organ cultures.

Mice vaccinated with a live attenuated strain of Salmonella dublin were protected against heavy challenge infections of S. dublin, S. typhimurium, S. choleraesuis and S. anatum. Oral and subcutaneous vaccination were equally effective. When day-old chicks were orally vaccinated and subsequently challenged with S. typhimurium, the growth of the challenge organism was considerably reduced or eliminated from the livers of the vaccinated chicks whereas most of the non-vaccinated were heavily infected. Field trials with vaccinated day-old chicks showed that they suffered no setbacks in growth, stress, loss of appetite or adverse side effects.

Human infections with Salmonella saintpaul have become more frequent in New Zealand in recent years. Most cases now occur in Otago. It is shown that wild lizards in Otago, particularly the common skink (Leiolopisma zelandica), carry S. saintpaul and that most if not all human outbreaks of this salmonella serotype are associated with either lizards or lizard infested areas. So far as is known this is the first report incriminating lizards as the probable cause of human salmonellosis.

Eight epidemics of respiratory disease have been observed among islanders of Tristan da Cunha. They seem to be initiated by the arrival of ships and transmission seemed to occur as a result of close human contact but could not always be traced. Islanders suffered from less colds than those in less isolated communities.

The two methods for measuring the haemagglutinin content of an influenza virus suspension are the haemagglutinating (HA) and chick cell agglutinating (CCA) techniques and both measure the same biological activity. With the establishment of an international reference preparation for influenza virus haemagglutinin (type A), however, it seems logical to express the haemagglutinin content of influenza vaccines in international units. Accordingly a collaborative study was arranged in order to obtain agreement on the number of units to be assigned to a British reference preparation for influenza haemagglutinin. It was agreed that the preparation contains 190 i.u. per ampoule and 1 i.u. is contained in 0·0622 mg. of the dried material.

A survey of microfilaraemia among the population of Vanua Levu, Taveuni and Koro islands in northern Fiji was conducted in 1968 and 1969 as a prelude to a campaign of mass treatment with diethylcarbamazine.

The prevalences of microfilaraemia were found in the more moist conditions of Taveuni and Koro and on the windward southern side of Vanua Levu to be higher than on the drier northern side of Vanua Levu. On both sides of Vanua Levu prevalences were lower inland than near the coast.

Under apparently similar environmental conditions those of Fijian ethnic origin exhibited a higher prevalence of microfilaraemia than that shown by Indians. This ethnic difference and a difference between the prevalences in male and female Fijians are considered to be due more to higher rates of recovery from microfilaraemia in Indians and Fijian women than to diminished exposure to mosquitoes. Mathematical models have been used as an aid to the interpretation of the data, and, where appropriate, comparison has been made with the prevalence of antibodies to dengue, an arbovirus having the same vectors.

Household infections were analysed by computer techniques. Infections in large households were not proportionately higher than in small households, indicating that transmission was not intrafamilial. The clustering of infections within households, though present, was not marked. Among the occupants of outlying settlements the prevalence of microfilaraemia was relatively low indicating a lower risk of infection due to isolation.

Surveys of arbovirus activity in Fiji were conducted over a 10-year period from December 1959 to December 1969. No arboviruses were isolated from over 200,000 mosquitoes, 9000 ticks, or 575 serum samples. Eight thousand human and 1117 bird, bat and animal sera were tested for haemagglutination-inhibiting arbovirus antibody using a variety of group A, group B and Bunyamwera group antigens. Only a small number of low-titre reactions were found among the non-human sera, but 14% of all human sera were found to contain Group B antibody. The antibody prevalence increased with increasing age, from less than 1 % for persons born since 1950, to 70% for persons born before 1900. The age differences in prevalence could be used to estimate the time and size of previous epidemics. Differences were found in antibody prevalence between the sexes, between ethnic groups and between persons from different regions. These differences could be explained in terms of climate, location and custom.

Historical and serological evidence both suggest that all the antibody detected was due to past exposure to dengue virus. The very high proportion of the population with no dengue antibody makes Fiji a high-risk area for a further dengue epidemic. Dengue virus is known to be active in the Pacific and South-East Asia.

During a filariasis survey conducted in northern Fiji in 1968–9 examinations were made for microfilaraemia, enlarged lymph nodes and elephantiasis. Analysis of the microfilarial densities at different ages and the number of anatomical sites showing lymph gland enlargement or elephantiasis have been used to provide evidence on the clustering of infections and pathogenesis.

Although there is no evidence of clustering of risk of infection, there is evidence favouring the clustering of adult filariae in individuals. Nevertheless the number of sites of lymph node enlargement do not correspond with this finding and statistical evidence suggests that lymph-node enlargement is not necessarily associated with the near presence in the body of adult filariae, whether dead or alive.

Males of Indian ethnic origin showed a higher prevalence of elephantiasis than males of Fijian ethnic origin, but women of either ethnic race showed prevalences lower than those of men.

The onset of elephantiasis at a site does not directly reflect the number of infections sustained in the local area, but it appears that filariasis first induces for a limited period a proneness to elephantiasis. During this period a random and discrete event may induce the onset of elephantiasis. The nature of the event is unknown, but it probably is not trauma.

In animals exposed to foot-and-mouth disease virus by indirect contact, virus was recovered from the blood, milk, pharynx, vagina and rectum for variable periods of time before clinical disease was apparent. Virus instilled into the mammary gland multiplied rapidly and virus concentrations greater than 107 p.f.u./ml. were recorded within 8–32 hr., depending on the virus strain and dose inoculated. Virus multiplication was accompanied by clinical signs of mastitis but the classical signs of foot-and-mouth disease did not appear for 52–117 hr. Dissemination of virus from the mammary gland occurred within 4–24 hr. and in some animals samples taken from the pharynx, mouth, nose and vagina contained virus for periods up to 97 hr. before the appearance of vesicular lesions. Virus production in the udder declined with the appearance of virus neutralizing activity in the blood and the milk but persisted in some animals for periods of 3–7 weeks. The ability of foot-and-mouth disease virus to persist in mammary tissue was confirmed by the demonstration of virus multiplication in the udders of immune animals.