Recent epidemiological studies have shown that death-rates from certain chronic diseases are higher in areas with soft than in areas with hard drinking-water. In the striking negative correlation found in the county boroughs of England and Wales between cardiovascular mortality and water hardness the important underlying factor is apparently the water calcium. Interest is therefore focused on the dietary significance of calcium present in drinking-water. In relation to that interest, the present report gives a quantitative account of the composition of tea infusions prepared with waters containing different amounts of calcium. It is shown that a substantial part of water calcium is taken up by the tea leaf during the preparation of infusions. The analysis of the infusions covers a wide range of individual components, including trace metals and polyphenolic substances. It appears that the principal change caused in infusion composition by the presence of calcium in the water is a substantial reduction in the relatively high oxalate content. The question is raised whether there may be some connexion between the ‘ water factor’ in cardiovascular disease and the absorption of oxalates from foods.

Ten strains of myocoplasmas were recovered from cultures of synovium or cultures inoculated with synovial fragments from rheumatoid arthritis and one from osteo-arthritis. The source of the organisms is not known. Patients with rheumatoid arthritis had no complement-fixing antibody and no fluorescent staining antibody against the mycoplasmas isolated and no mycoplasma antigen was detected by immunofluorescence in sections of synovia and in synovial fluids.

The strains isolated were of two main serological types and could be distinguished by direct fluorescent antibody staining from standard types of human commensals and the common tissue-culture contaminants. One may be Mycoplasma laidlawii.

This paper reports a study carried out to clarify the mechanisms involved in adsorption of influenza A and B viruses on iron oxide. Accordingly, the amounts of virus that are adsorbed from virus suspensions of varying concentrations per unit surface area of magnetic or non-magnetic oxide at fixed temperature and time have been determined. The principles involved are clearly the same as those involved in multiple equilibria during the interaction of particles with a large number of combining sites with different intrinsic affinity. Consequently, the amount of virus that is adsorbed per unit mass of iron oxide depends on the size of the adsorbent area, not on its magnetic property. Owing to a significant difference between the affinities of influenza A and B particles for the binding sites on iron oxide, unit surface area of the adsorbent is invariably capable of adsorbing significantly greater amounts of influenza A than B particles. The practical implications of these findings are that a better understanding of the mechanisms involved in virus adsorption on iron oxide will permit a more efficient separation of virus particles from impurities. The simplicity and the rapidity of the technique and the cheapness of the equipment required suggest that the iron oxide method is of great value for both small- or large-scale viral purification, whether it is used as a single step procedure or as a primary step followed by zonal separation.

Dissociating chemical treatments employing surfactant-solvent systems were applied to purified influenza A and B viruses to obtain viral preparations possessing a significantly higher or lower haemagglutinating activity than the intact virus. All preparations, whether with high or low haemagglutinating activity, with the exception of envelope protein solubilized by Triton X-100, were significantly lacking in the ability to excite the formation of haemagglutination-inhibiting and virus-neutralizing antibodies in inoculated ferrets. In contrast to other treatments, Triton X-100 treatment of virus significantly enhanced the antigenicity of viral protein as judged by virus neutralization and haemaggmtination inhibition tests. Yet the haemagglutinating activity of the envelope protein solubilized with Triton X-100 was about 1 % that of the intact virus. Results suggest that the correlation assumed to exist between the haemagglutinating activity of influenza virus and its ability to excite the formation of humoral antibodies is coincidental. Another important point is that the specific antigenicity of viral protein may be lost or enhanced owing to effects, other than solubilization, by surface-active agents.

A survey of the species composition and distribution of the Culicoides midge populations at a range of sites where bluetongue is enzootic isolated a group of dominant species: C. cornutus, C. grahamii, C. magnus, C. milnei, C. pallidipennis and C. 23.† Monthly light-trap sampling of Culicoides showed that the population densities of the dominant species greatly increased after the rain seasons and that these species concentrated around flocks of sheep and cattle. The larval habitats of C. cornutus and C. pallidipennis were found associated with stock pens. Precipitin tests on blood-fed Culicoides showed that most of the dominant species regularly feed on sheep and cattle. Bluetongue virus was isolated from C. milnei, C. pallidipennis and C. 23. Serological surveys of wild and domestic bovids from the enzootic area showed a high proportion with antibody to bluetongue virus. The colonization of C. cornutus, a potential vector, is described briefly. A causal relationship between peak rainfall in April-May, peak numbers of Culicoides in May-June and peak bluetongue incidence in June-July is postulated. The vector status of the above species and C. austeni was evaluated.

Cationic proteins isolated from the cells in bulk milk samples were shown to inhibit the growth of two pathogenic strains of staphylococci and also Streptococcus agalactiae S 13. Polyacrylamide gel disk electrophoresis studies on these proteins revealed the presence of at least 9 components some of which had isoelectric pH's between 7·0 and 9·0. Trace amounts of the isolated protein had isoelectric pH's greater than 9·0. Staphylococci incubated with milk-cell cationic proteins absorbed the protein, thereby allowing the organism to be stained with the anionic dye Fast Green FCF. Protein-treated staphylococci in isotonic solutions autoagglutinated. This autoagglutination was more marked in hypo- and hypertonic solutions. Lysozyme was not demonstrated in the isolated protein fractions in assays involving incubation with Micrococcus lysodeikticus for 90 min. The antimicrobial activity of the cationic proteins isolated from the bulk milk samples was not destroyed after heating to temperatures up to 70° C for 30 min., whereas at higher temperatures the activity diminished and was almost completely lost at 100° C.

Individually caged house mice (Mus m. musculus) were fed 0·025% warfarin (3(2-acetyl-l-phenylethyl)-4-hydroxycoumarin) or 0·025% chlorophacinone (2-(l-(p-chlorophenyl)-l-phenyl) acetyl-l,3-indandione) for periods varying from 1 to 21 days. In all, 320 mice, 160 of each sex, were tested.

A significant difference was found between the mortalities obtained by the two compounds. In feeding periods varying from 1–5 days chlorophacinone produced a mortality of 60–85 % and warfarin only 5–75 %. Five per cent, however, did survive 21 days feeding on each compound.

A great variation in the susceptibility of individual mice was established for chlorophacinone as well as for warfarin.

Serum cholesterol in rabbits was elevated, by intravenous inoculation of 20 % Tween 80, to amounts thought to have been sufficient to support growth of Mycoplasma gallisepticum when 20 % of such serum was added to rabbit infusion broth.

However, better growth of the organism was obtained with a supplement of 5 % rabbit serum and commercial cholesterol. Investigation showed that normal rabbit serum may be inhibitory, which would explain these findings. The commercial cholesterol was not antigenic.

The efficacy of horizontal and vertical laminar flow units (equipped with high-efficiency air niters) in the prevention of cross-contamination between cages and of contamination from outside has been demonstrated. With germ-free mice and using germ-free standard techniques for sterilization and for the transfer of germ-free mice into the cabinets via a standard entry lock, it was found that during an observation period of 2 weeks the animals remain ‘negative’. Other experiments were performed with equally good results in cabinets equipped with a hinged flap, closing 95 % of the open front side. When the flap was closed the air flow could be reduced accordingly, thus reducing the noise level and the risk of dehydration.

Experiments made with germ-free mice in a ‘down-flow unit’ were also invariably good.

In another type of experiment, cages with conventional mice were placed in the cabinets between cages with germ-free animals at varying distances. If all animals were maintained on wire mesh (to minimize the aerosol production of dust) and if the ‘conventional’ cages were at a distance of 10 cm. from ‘germ-free cages’ the latter remained bacteria-free during test periods of one week.

The use of ‘laminar flow isolators’ for the isolation of human patients is mentioned.

Between October 1968 and February 1970, 30 strains of cytomegalovirus were isolated from the urine of children admitted to hospitals in Lyon. Three groups of children up to the age of 14 years have been investigated.

The first group consisted of 304 newborns and infants up to the age of 1 year; cytomegalovirus was grown from five of these (1·6%). Among these five children, two had cerebral disorders. None of them had ever shown any sign of typical CMV infection.

The second group comprised 102 children between the ages of 1 and 14 years, from a special service for neurological and mental diseases. Cytomegalovirus was grown from 19 (18·6%).

The third group was 27 children also between 1 and 14 years of age, admitted to hospital for miscellaneous diseases excluding cerebral disorders; cytomegalovirus was grown from six (22·2%).

It appears that cytomegalovirus has a very low incidence in neonatal disease. The virus spreads at a higher rate in children 1–14 years old. No difference has so far been shown in the excretion rates of two groups of children, one with cerebral disorders and one with other diseases, but the number of children in the last group is too small to allow definite conclusions to be drawn.

The use of the hypergeometric distribution in calculations of sample volumes for safety testing is criticized. Alternative interpretations of the concept of ‘infective ml. doses’ lead to slightly different solutions, the simplest of which, involving the exponential function, is recommended for general use.

Both the haemagglutinin and the neuraminidase of influenza A 2 virus have undergone progressive antigenic drift since this subtype first appeared in 1957.

In 1968 a strain showing a much greater antigenic difference was isolated in Hong Kong. This variant has been responsible for epidemics throughout the world in the past 2 years.

In the second year of its prevalence a small proportion of strains isolated showed a small but definite antigenic change, related principally to the haemagglutinin component.

This new variant formed about 4 % of all strains investigated and was detected in Britain, Portugal, France and New Zealand.

Field experiments were made in southern England to re-examine the possibility that mosquitoes in Britain might feed on wild rabbits and hence be vectors of myxomatosis. Mosquitoes of several species were attracted to rabbits enclosed hi cylindrical traps and in a trap in which the animal was placed in a wire mesh cage. Substantial numbers of mosquitoes were also caught biting, or attempting to bite, tethered rabbits which were not in cages or traps. Evidence that mosquitoes fed on wild rabbits under natural conditions was obtained from results of precipitin tests made on blood-smears collected from mosquitoes caught resting amongst vegetation. On a few evenings mosquitoes were seen to be attracted to healthy wild rabbits and apparently attempting to feed on them. Batches of two mosquito species collected from the field were infected with myxoma virus.

It was concluded that contrary to previous beliefs mosquitoes in Britain feed to a certain extent on wild rabbits, and therefore are potential vectors of myxomatosis. No attempts were made to assess their relative importance in the transmission of the disease, which in Britain is transmitted mainly by the rabbit flea.

The spread of coagulase-positive staphylococci has been studied in a modern hospital in which most of the patients were nursed in 4-bed rooms separated from a common corridor only by low dividing walls. Acquisition of new nasal strains from patients in other bedrooms was nearly as easy as from patients in the neighbouring beds. There was no indication that subdivision of this type hindered the spread of nasal strains as compared with open wards of the ‘Nightingale’ pattern.

Studies on infections in a hospital for diseases of the skin are described. Patients were shown to acquire staphylococci in the groin and on the chest at about the same rate as in the nose. In contrast to surgical wards, many staphylococci were resistant to tetracycline but sensitive to penicillin. Nevertheless, much of the epidemic spread of staphylococci was with typical surgical-ward strains rather than with phage group II strains which might be thought typical of skin diseases.

The germicidal efficiencies of hot water (140–150° F.) under pressure (method 1), hot water + 2% (w/v) detergent solution (method 2) and hot water + detergent + 200 p.p.m. solution of available chlorine (method 3) were compared at six sites in a bacon factory. Results indicated that sites 1 and 2 (tiled walls) were satisfactorily cleaned by each method. It was therefore considered more economical to clean such surfaces routinely by method 1. However, this method was much less efficient (31 % survival of micro-organisms) on site 3 (wooden surface) than methods 2 (7% survival) and 3 (1% survival). Likewise the remaining sites (debarring machine, black scraper and table) were least efficiently cleaned by method 1. The most satisfactory results were obtained when these surfaces were treated by method 3.

Pig carcasses were shown to be contaminated by an improperly cleaned black scraper. Repeated cleaning and sterilizing (method 3) of this equipment reduced the contamination on carcasses from about 70 % to less than 10 %.

Desiccates of Salmonella ndolo dried in sodium glutamate have been exposed to 100° C. in air or in vacuo; in the presence of wet or dry P2O5; and with desiccant maintained at either 25° or 100° C. Of the eight treatments thus compared, rapid killing occurred where the desiccate was heated in vacuo and in the presence of dry P2O5 maintained at 100° C. There was little difference among the death-rates of the other seven treatments. Sublimation of the P2O6 with resultant attack on the desiccate would appear to be responsible for the rapid killing in the treatment where it was observed.

Nine gnotobiotic piglets, when 8–9 days old, were exposed to an aerosol of strain TR 32 of Mycoplasma hyorhinis and killed at intervals from 14 to 37 days after infection. The aerosol of M. hyorhinis caused bronchopneumonia in 1 pig, pleurisy alone in 2 pigs, pleuropneumonia in 2 pigs and no lung changes in 4 pigs. M. hyorhinis was re-isolated from the lungs of all infected pigs, irrespective of the presence or absence of lesions, though it was only isolated from the serosa and joints when lesions were present. Four control pigs exposed to aerosols of mycoplasma medium had no lesions.