Mice from Loughborough and Nottingham were obtained in order to compare the inheritance of warfarin resistance in these populations with that established for a Cambridge population (Wallace & MacSwiney, 1976). Using the same breeding programme and warfarin testing technique, it is established that resistance in the new areas is, as in the Cambridge area, controlled by the major resistance gene, War, in chromosome 7, with penetrance affected by sex and modifiers. In addition, survival differences in males of different ages strongly suggests that War + has less penetrance with age. Penetrance differences between the experiments establishes that wild populations differ in their modifier complex and that more than one modifier, probably several, exist. Questions are posed as to the adaptive significance of the phenomena, and the way in which they work, in the patchwork of warfarin baited and unbaited areas in this country.

A modification of Sharpe's microdroplet counting technique is presented which permits viable counting of Bacteroides fragilis. Lysed horse blood was added to 0·1 ml soy digest agar droplets and 2% was found to be the optimal concentration which combined adequate intradroplet colony size with acceptable visibility on the counting screen of the Colworth Droplette machine.

Baiting with medium oatmeal or soaked wheat containing 0.002, 0.001 or 0.0005% brodifacoum completely controlled infestations of warfarin-resistant rats on farms when the poisoned baits were maintained until rats ceased to feed on them. The concentration of brodifacoum did not affect the duration of these treatments which lasted from 11 to 25 days.

Poison baiting with 0.002% brodifacoum for only 1, 4 and 7 days achieved, respectively, only about 41, 51 and 68% control of similar farm infestations, and so emphasized the need to continue baiting for longer periods.

A model activated sludge treatment plant was used which was functionally very similar to a full-scale plant. It was inoculated with f2 coliphage and the titres of virus in the influent, the mixed liquor and the effluent were monitored regularly. The distribution of the virus in the solids and liquid fractions of the mixed liquor was in the ratio of 18:82 and 20–4 % of the influent virus was recovered in the effluent. After inoculation was stopped the titre of virus in the solids fraction of the mixed liquor remained high and unaltered for up to 70 h, whereas the value for effluent reverted to the low background titre originally present. These results are discussed in relation to those reported for poliovirus and it is concluded that f2 coliphage is not a suitable model for studies of the behaviour of human enteroviruses.

The indirect ELISA technique has been developed successfully to measure antibodies to foot-and-mouth disease virus (FMDV) in cattle sera. Preliminary studies using a standard serum assay show that reproducible results are obtained. The method should prove useful for the examination of antibody titres in sera from large numbers of cattle or other animals.

Volunteers were inoculated with vaccine made from the 30c mutant, A/Port Chalmers/73 or B/Hong/8/73. Preliminary experiments showed that the 30c strain was antigenically quite close to A/HK/8/68. Volunteers given 30c developed haemagglutination inhibiting antibodies against the ‘current’ 1973 serotypes (as well as to the vaccine virus) but the titres were less than those after the A/PC/73 vaccine. Volunteers were then challenged with a live attenuated virus, WRL 105, with A/Finland/4/74 antigens, by intranasal inoculation. The rates of infection were 43% after B/Hong Kong/8/73, 20% after 30c and 5% after A/PC/73. This indicated that the 30c gave some protection but the vaccine prepared from the current strain gave more.

The sources from which different ‘OH’ serotypes of Escherichia coli have been isolated are listed in a series of tables. It is considered that these tables should provide a basis for obtaining a greater understanding of the ecology of E. coli.

The properties of pyriminyl (N-3-pyridylmethyl-N′-p-nitrophenyl urea) as a rodenticide against the lesser bandicoot rat (Bandicota bengalensis) in Rangoon, Burma, were investigated in the laboratory. The acute LD 50 and LD 95 dose of orally administered pyriminyl for B. bengalensis were found to be 6·7 mg/kg and 23·0, mg/kg of body weight respectively. When caged bandicoots were given a choice between plain and poisoned baits, the optimum rodenticidal concentration in the bait was found to be 0·25–0·5%. Symptoms of pyriminyl poisoning appear from 1 to 4 h after feeding starts, giving individual animals time to consume from 2 to over 30 LD 50 doses of 0·5% pyriminyl before feeding stops. Deaths occurred from 4 to 96 h after either oral dosing or free-choice feeding. There appeared to be no significant aversion to the poison at 0·25% or 0·5% concentration in foods. The potential hazards and use of pyriminyl as a field bait against populations of B. bengalensis are discussed.

In the 15 months, February 1976 to April 1977, more than 241 patients became colonized with a strain of Klebsiella aerogenes, capsular serotype K2, resistant to most antibiotics. Urinary tract infection was the most common clinical manifestation but bacteraemia and, occasionally, infections of other sites were encountered. The main reservoir of the epidemic klebsiella was the gut, urine and skin of colonized patients. Gut carriage among staff was very uncommon. The most susceptible patients were elderly males, with debilitating illnesses and urinary tract abnormalities, especially if they were catheterized or receiving antibiotics. Likely vehicles for spread were the hands of staff, and contaminated bedpans and urinals. Control measures were directed at these factors. At the end of April 1977 no new cases had occurred for 3 months in the ward in which the outbreak began, and which had been the main focus of infection, and only 5 patients in the affected hospitals were known to be colonized by the epidemic klebsiella.

Influenza activity was studied in the Rome population from 1956 to 1976 by analysis of mortality from respiratory causes and from all causes. During cold weather months, type A influenza virus was associated, as a rule, with epidemic excess deaths at two year intervals while type B virus was prevalent twice during epidemic excess mortality periods. Excess absenteeism from work and virus isolation data were also compared with epidemic excess mortality during four consecutive years. The evidence obtained indicated that influenza virus isolation alone does not represent a reliable index of epidemic influenza activity in this population. The proportion of deaths attributed to respiratory causes consistently increased in every epidemic, the most pronounced increases occurring during large epidemics. The break-down by age of deaths from respiratory causes in the course of two epidemic periods showed that the percentage distribution of deaths was essentially the same as in non-epidemic periods. This evidence indicates that the same factors influencing the age-related distribution of mortality from respiratory causes during non-epidemic periods, probably affect the fatal outcome of influenza during epidemics.

Raw sewage sludge, containing up to 105 naturally occurring salmonellas/l, was included in the diet of one group of cattle at the rate of 1 l/animal/day and in a second group at the rate of 1 l/animal/week. Sterilized sludge, to which had been added 105S. dublin/litre, was included in the diet of a third group of animals at the rate of 1 l/animal/day.

Salmonellas were isolated from all samples of raw sewage sludge but were not isolated from the faeces or carcasses of animals fed on the sludge. Salmonellas were isolated from the faeces of one animal and the carcasses of two animals fed on sterilized sludge to which S. dublin had been added.

In these studies it is shown that the common ‘British’ and ‘American’ adult cockroaches can survive exposure to formaldehyde fumigation carried out at double the strength and for four times as long as is recommended for disinfection of rooms.

It is further reported that vaccinia virus ingested prior to the fumigation survives in the cockroach gut and may be excreted up to 5 days later.

Since cockroaches are ubiquitous and are to be found in most hospitals, laboratories and animal houses, these findings should be considered whenever fumigation is called for.

An investigation of the in vitro responsiveness of peripheral blood lymphocytes to tetanus toxoid was undertaken to determine the extent to which such reactivity might reflect in vivo reactions to tetanus toxoid immunization. It was found that lymphocyte transformation in the presence of tetanus toxoid, as measured by the uptake of tritiated thymidine, did not differ significantly for the group giving local or systemic reactions to tetanus toxoid and an immune control group. However, a striking inverse relation between lymphocyte reactivity to tetanus toxoid and age of the cell donors of both groups became clear. Such an age-related decline in the in vitro responsiveness of peripheral blood lymphocytes to a specific antigen has apparently not been reported previously in man.

Serum samples collected from swine and cattle in Great Britain at various times between July 1971 and July 1977 were examined by haemagglutination-inhibition or single radial haemolysis methods for evidence of infection with influenza A (H3N2) viruses. A small proportion of swine sera collected in each year reacted in the tests but there was no evidence of infection in cattle. The significance of the findings is discussed, with particular reference to the seasonal fluctuations in the prevalence of antibody in swine observed during the period of the study, and their possible relevance to influenzal events in the human population. None of the sera tested had antibody to swine influenza strains (HSw1N1).

The potential value of oral erythromycin for antitetanus prophylaxis in non-immune patients with open wounds was assessed. Serum obtained by venepuncture from healthy persons 2 h after an oral dose of an erythromycin preparation was used as a culture medium rendered anaerobic by addition of cooked meat. Strains of Clostridium tetani inoculated into these sera failed to multiply when the donor had taken 500 mg of erythromycin estolate before a meal; other erythromycin preparations and the estolate at a dosage of 250 mg were ineffective or inconsistent in their inhibition of the growth of Cl. tetani.

Human antitetanus globulin (ATG) was given to 12 patients, 9 with severe injuries and 3 with extensive burns, all of whom were judged, from their history, to be non-immune (or with expired immunity); all except one had received large intravenous infusions of blood and/or other fluids. Serum antitoxin assays by a mouse protection technique on days 0, 1–2, 3–5, 6–10 and 14 + showed no detectable antitoxin (< 0·01) unit/ml) in the initial (pre-ATG) sample from three patients with severe injuries and in one with extensive burns. All the patients in the severely injured group showed an early appearance or increase in tetanus antitoxin to protective titres. Two of the three severely burned patients showed, respectively, delayed appearance or an increase in antitoxin; the other burned patients showed a reduction from the initial pre-ATG titre, followed by a return to that titre after day 5.

Adult cockroaches were found to survive up to 22 weeks when provided with 1% Formalin (0·4% formaldehyde) in lieu of drinking water. Given 4% Formalin or 2% glutaraldehyde they survived up to 41 days. During the experiments eggs were laid and hatched and the offspring continued to grow. Combined with surface disinfection, this may hold out a simple method of rendering adult cockroaches gnotobiotic or even axenic.

Two epidemics of water-borne diarrhoeal disease involving a total of 1000 persons are reported. In both epidemics, none of the usual bacterial enteropathogens were recognized and Plesiomonas shigelloides was the only suspect aetiological agent isolated. The ecology of P. shigelloides was investigated in these outbreaks. It was recognized as an inhabitant of fresh surface water and its presence was closely related to warm weather.

The normal flora of cockroaches (Periplaneta americana) was determined over a period of 24 days prior to substituting water with 1% Formalin for drinking water. During the first 4 days of treatment the normal flora was significantly reduced and by the fifth day, when the cockroaches became diarrhoeic, no bacteria, fungi, or viruses could be detected by the methods used.

An episode of nosocomial infection with Klebsiella aerogenes in a surgical ward, in which six patients were infected, is described. The cause of the outbreak was identified as being contaminated washing-bowls. It is recommended that each patient should have his own bowl, which should be disinfected after use, dried and stored upside-down.

A collaborative survey has shown that V. parahaemolyticus is widely distributed in British coastal waters, sediments and shellfish, especially in southern and western areas. The relatively small numbers in the environment do not present significant health hazards from marine products, provided that processing, storage and distribution are adequate. The presence of this organism in small numbers in British coastal waters or in shellfish should not in itself be regarded as cause for concern.