Experiments carried out by the British Egg Marketing Board in order to establish a heat treatment which would effectively pasteurize liquid whole egg are described.

The results of large scale bakery trials and subsequent trade demands indicate that the recommended pasteurization treatment gives a product of a satisfactory baking performance.

It is recommended that for the adequate pasteurization of whole-egg products, a temperature of 64·4°C. (148° F.) for the minimum holding time of 2·5 min. should be used.

The activity of the enzyme α-amylase of whole egg is known to be sensitive to pasteurizing temperatures and the possibility that this property could be used as a control test for the adequacy of pasteurization has been examined.

The occurrence of the enzyme, the physico-chemical characteristics of its heat inactivity, the consistency of its behaviour in large numbers of eggs and the influence on its of packing station procedures has been studied.

By sampling eggs from many sources for 11 months it was concluded that the activity of the enzyme was consistent, the inactivation by heat was a first-order reaction, and freezing, thawing, homogenization, spray-drying and in the laboratory freeze-drying did not affect its inactivation. But there was some interference from added citrate and sucrose.

The conditions of heating necessary to destroy salmonellae in liquid whole egg have been compared with those necessary to destroy the activity of the α-amylase of whole egg. All conditions of pasteurizing from the mildest at 61·1° C. (142° F.) for 1 min. to the most severe at 65·5° C. (150° F.) for 5 min. eliminated Salm. typhimurium. The heat-resistant strain of Salm. senftenberg N.C.T.C. 9959 (775 W) was not recovered after heating at 64·4° C. (148° F.) for 2½ min. and at the lower temperatures when the heating period was 3 min. or more. The activity of α-amylase was also destroyed by heating at 64·4° C. (148° F.) for 2½ min. but not at lower temperatures.

Because the baking properties of egg are not impaired by heating at 64·4° C. (148° F.) for 2½ min. it is proposed that the inactivation of the α-amylase of whole egg can be used as a test for controlling the pasteurization process, and a routine test has been developed which can be completed within 1 hr.

Of the ordinary infections sustained by children during the first 5 years of life 56% were common colds, 16·5% other infections of the respiratory tract, 16% gastro-intestinal catarrhs, 6% infections of the skin and mucous membranes and 5·5% infectious diseases in a strict sense.

Common colds were most frequent in the second year, namely, an average of 4·3 common colds per child per year. As the child grew older the number of colds decreased. Adults showed an average of two common colds per year.

Of the ‘other infections of the respiratory tract’, 42% were undifferentiated respiratory tract infections, 23% febrile affections without definite localization, 17% otitis, 11% pharyngitis and 7% influenza. The frequency of these ‘other infections of the respiratory tract’ rose from 0·3 in the first to 1·8 in the fifth year of life. After the fifth year the frequency diminished to one infection every 2 years in adults.

The frequency of gastro-intestinal catarrhs in the first year of life, namely, 0·6 per child per year, was doubled in the second year, and then remained constant for a few years. After the fifth year a decrease was observed in this figure too.

Fifty-four per cent of the 116 index children sustained at least one suppurative skin affection during the first 5 years of their lives, 28% had more than one. Most pyodermias occurred in the first few months of life, a second maximum being observed in schoolchildren, 21% of the index children had stomatitis in the first 5 years, 42% conjunctivitis.

By their fifth birthday, 49% of the 116 children had had measles, 46% chicken pox, 26% rubella, 24% exanthema subitum, 17% mumps, 3% whooping cough, while 2 of the 116 children had had scarlatina, 1 child hepatitis, 1 poliomyelitis and 1 bacterial meningitis.

No difference in morbidity was found between boys and girls in respect of respiratory tract infections. The boys had skin infections distinctly more often than the girls, and infections of the mucous membranes and of the gastro-intestinal tract were also slightly more frequent in boys. Apart from infections of the skin and mucous membranes, which were more often observed in mainly bottle-fed children, ordinary infections were equally frequent in this latter category and in children mainly breast-fed.

The index child with older brothers and sisters contracted the ordinary infectious diseases younger than the index child who was the eldest child in the family. On account of the presence of older children in the family, a child was ill not more often, but earlier. The infections of the respiratory tract showed a distinct preference for the winter months, and the frequency of gastrointestinal infections was also slightly higher in that season.

Febrile affections without definite localization, as well as infections of the oral mucosa, occurred especially during the summer months.

Going to the kindergarten did not lead to an increase of the frequency of common colds and gastro-intestinal catarrhs, but the number of infectious diseases in a strict sense became higher. The ‘other infections of the respiratory tract’ became more frequent under the influence of school only in those index children who were the eldest in the family. The index children from families with a low level of hygiene experienced more infections of the skin and mucous membranes than those from families with a high hygienic level.

No difference between these two groups was demonstrable in regard to the other ordinary infections.

There was a parallelism between the frequency of common colds and of gasto-intestinal catarrhs but not with the other minor infections.

A technique involving the suppression of normal intestinal flora with antibiotics, and the introduction of streptomycin-resistant coliforms was used for the study of infections in mice.

It was shown that Escherichia coli, both the enteropathogenic and normal faecal strains, tend to colonize the upper intestinal tract as well as the lower region. An oral dose of ten or less cells could produce a chronic infection. Infections were asymptomatic even with an initial dose of 109 bacteria. There was no indication of growth advantages for enteropathogenic coliforms in competition with normal.

1. Fifteen apparently healthy persons were exposed to air enriched with positive or negative ions at 78° F. and 87° F. Average ion counts at 78° F. were 12,324 positive ions per ml. and 5,451 negative ions per ml. The averages at 87° F. were 14,865 positive ions per ml. and 5,442 negative ions per ml. Relative humidity was kept at 50% and air motion was 28 ft./min.

2. Seven sensations related to comfort (thermal sensation, humidity sensation, sensible perspiration, air motion, pleasantness, mood and fatigue) were recorded, pulse rate and oral temperature were measured.

3. In the experiments at 78° F. mood was improved (P < 0·001) by positive ionization. All other qualities remained unaffected by positive ionization. No effect was found under negative ionization at the ion concentration applied.

4. In the experiments at 87° F. five sensations (thermal sensation, sensible perspiration, pleasantness, mood and fatigue) were significantly (P < 0·001) improved by ionized air. In general, as can be seen from the significantly differences between grand means, the subjects felt cooler, perspired less, felt more pleasant, were in a better mood, and felt less fatigued under the influence of air enriched with ions.

Air motion sensation, humidity sensation, pulse rate and oral temperature were not affected by ionization.

5. As different individuals may vary in their response to ionization, individual preferences were tested. These tests indicated that at 87° F. six out of the fifteen persons tested preferred ionized air (P < 0·001). One person preferred air not enriched with ions (P = 0·0091).

This paper elaborates a concept of enrichment dynamics introduced in an earlier paper in which the author set out to find a labour saving technique for isolating salmonellac from sources other than faeces. Extensions to the concept are summarised in the Introduction. Explanations are given why a multiplicity of isolation procedures used in combination should normally yield more isolations than any one procedure alone.

Since a limit must always be set on the number of different media and procedures which can be used during routine examinations, a corresponding limit has also to be set on the combined efficiency of the procedures used. Not even a very laborious combination of methods can be expected to yield quite 100% of the isolations that are technically possible. When this rather unpalatable conclusion is accepted, a way is opened up for compromises between endeavour and reward, in terms of salmonella isolations. Judicious application of principles and methods discussed in these papers might be expected sometimes to lead to modifications in techniques which increase their efficiency, and in other cases to modifications which reduce labour without diminishing efficiency.

A controlled trial of Naseptin cream, as an anti-staphylococcaiprophylactic, made in two adult wards, showed the cream to be effective in reducing nasal carriage, including antibiotic resistant strains. There was no marked effect on wound infection.

A controlled trial of Naseptin cream and Sterzac powder prophylactically in maternity nurseries was found to be effective in reducing nasal carriage and infection.

These findings are discussed, and recommendations on the use of Naseptin cream as a prophylactic are made.

Zone electrophoresis in a sugar concentration gradient is proposed as a complementary method for the biological classification of the enteroviruses. Under standardized experimental conditions it was found that the majority of the Coxsackie A viruses and the polioviruses have a common, low electrophoretic mobility. sackie A viruses and the polioviruses have a common, low electrophoretic mobility. The impression was gained that the ECHO viruses show the highest electrophoretic mobility, though in some cases there is overlapping with the Coxsackie Bs. The mobility of both of these groups is considerably higher than that of the other two.

Zone electrophoresis appears to be an excellent method for the purification of the enteroviruses prior to the production of specific precipitating antibodies.

1. In two R.A.F. recruit stations between November 1958 and March 1959, there were 2603 admissions to Sick Quarters with respiratory illness. Throat swabs from 1129, and paired sera from 1197 were tested for certain respiratory viruses.

2. From the serological results it was estimated that 19% of the admissions were associated with influenza A infection, 7% with influenza B, 26% with adenovirus, 1% with para-influenza Type 1, 1% with para-influenza Type 3 and 8% with Coe virus, but as 21% of the identified infections were multiple the proportion of illness associated with one or more of these infections was only 50%. Thirty-four per cent of the Coe virus infections and 56% of the para-influenza virus infections were multiple.

3. Virus isolation test results led to a similar estimate of the frequency of adenovirus infection (23%) but to a lower estimate for Coe virus (3%) and for the para-influenza viruses, no systematic attempt was made to isolate influenza viruses. Reasons are given for thinking that most of the admissions associated with Coe virus infection in 1958, but few of those in 1959, were caused by this agent. The proportion of illnesses attributable to viruses of the para-influenza group was probably about 1%.

4. The main symptoms associated with Coe virus infection were upper respiratory. Hoarseness was rather more prominent than in other infections but the height and duration of fever and the frequency of febrile symptoms were less. The few illnesses associated with para-influenza virus infection had no obvious distinguishing features.

1960 survey

1. Blood specimens were taken from 205 recruits on their arrival at a recruit camp in January 1960 and immediately before their departure in March; 764 men in ten operational stations were bled in January and a sample of 260 were bled again in March.

2. The respiratory illness admission rate was 25% in the recruits and 4% in the trained men; 49% of the recruits showed a rise in antibody to one or more respiratory virus antigens compared with 2% in the other group. The high rate of infection in recruits was mainly due to adenovirus (36%) and Coe virus (20%).

3. It was estimated that about a third of the adenovirus infections and an eighth of the Coe virus infections were responsible for illness requiring admission. There was no indication that either infection caused any appreciable number of less severe illnesses not requiring admission.

4. Evidence from this survey and the earlier one suggests that the presence of neutralizing antibody to Coe virus does not prevent infection, though it appears to lower the probability of illness.

When killed radioactive bacterial spores are inhaled by guinea-pigs and retained in the lung, it is found that the rate of loss up to 5 weeks later is sufficiently constant for the initial retention of a group of animals to be calculated from the measured retention at a later time (say 3 weeks after exposure). If, therefore, the inhaled cloud contained also a pathogen, in known proportion to the spores, the initial retention of the pathogen could be calculated. The experiments apply to groups of animals, but it is believed that the conclusions are valid also for single animals. In experiments with Br. suis it was found that the fate, as regards infection, of individual animals within a group exposed to a common dosage was not significantly related to the estimated retained dose, despite the wide variation of individual doses about the group mean.

1. A bacteriological laboratory was provided in the medical departments of two passenger ships—a modern luxury liner cruising in the Mediterranean for 1 month and an older vessel, now out of commission, on a 3 months round voyage through the tropics. Galley hygiene in relation to gastro-enteritis was investigated on both ships.

2. 125 samples of water and iced water were examined. Samples of water chlorinated on the ships were usually satisfactory. Many port waters sampled from the barge or hosepipe were contaminated—some mildly, some profusely. A fault in an ice-making machine led to pollution of ice used for various purposes. Swimming-bath water was usually mildly polluted only; occasionally in the tropics when the baths were very popular the count rose to 1600 Esch. coli per 100 ml.

3. Thirty-five samples of milk, ice-cream and churn washings were examined. English liquid pasteurized milk stored in the cold gave satisfactory results, but the rehydrated dried milk used exclusively on the round voyage through the tropics and swabs from the apparatus used in its preparation were contaminated with Esch. coli. Ice-cream samples from ship I gave satisfactory results, and of two samples of ice-cream powder examined on ship II one was satisfactory and the other gave a poor result. Occasional churns which had been superficially cleaned but not sterilized had a high general and Esch. coli count.

4. 189 samples of food were examined, twenty-two for general and coliform counts only. Results were variable according to foodstuff and atmospheric temperature. Some cold cooked meatstuffs gave low counts and absence of coliform bacilli in 1/10 g.; others had plate counts of 300,000 to 25 million per gram with Esch. coli in 1/1000 dilution, e.g. crayfish ready for the table. Salmonellae were not found in any samples but occasionally small numbers of coagulase-positive staphylococci and non-haemolytic Cl. welchii were isolated.

5. Sixteen samples of imitation cream and washings from savoy bags were examined. Samples from freshly opened cans of cream gave satisfactory results. In whipped cream and in cream from cakes and sweets, Esch. coli was found in 1/1000 dilutions, and rinsings from savoy bags in use gave probable numbers of Esch. coli of 18,000 + / 100 ml. Counts were still high after the bags had been washed and dried and they were far from sterile even after ‘boiling’ and drying.

6. Twenty-three samples of wash water from salad vegetables and fruit had high counts of Esch. coli. After these articles had been washed in water containing 80 p.p.m. sodium hypochiorite, coliform organisms were not found in 100 ml. of water. Potassium permanganate was considered to be of doubtful value. The results of laboratory experiments to confirm the concentration of hypochiorite and time necessary to destroy Esch. coli on lettuce and watercress are shown in Tables 3 and 4.

7. Results from forty-four samples of wash and rinse waters from dish-washing machines and one bowl showed that the temperatures were often too low; with temperatures above 50° C. coliform bacilli were absent in 1 ml. quantities, but waters at temperatures below 42° C. gave probable Esch. coli counts of 1800 + / 100 ml. The bacteriological condition of the crockery and cutlery varied according to the wash and rinse waters. Rinses from metal dish covers gave poor results, with 1800+ Esch. coli per 100 ml. of rinse and occasionally Cl. welchii and coagulase-positive staphylococci. Wash and rinse waters, with temperatures of 35°ndash;42° C. used for pots and pans gave probable Esch. coli counts of 1800 + /100 ml.

8. Rinse waters from twenty cloths used in the galleys, pantries and dining rooms were nearly all heavily contaminated with Esch. coli, with probable numbers of 18,000 + /100 ml.; these counts were reduced to negligible figures by soaking the cloths in chloride of lime.

9. Swabs were taken from thirty-eight cutting-boards and twenty-six surfaces of sinks, shelves and miscellaneous articles. Many boards were heavily contaminated, the probable number of Esch. coli being 18,000 + /100 ml. of diluent; lecithinase-positive clostridia were found also. The boards could be sterilized by brushing with a stout wire brush followed by chlorination.

Other surfaces, and swabs from various knives in the kitchen, including the blade of the slicing machine, frequently gave high counts of Esch. coli.

10. 329 swabs from nostrils and fingers of saloon and galley staffs yielded one cutlure of coagulase-positive staphylococci from 111 nasal swabs and three cultures of coagulase-positive staphylococci and seven of Esch. coli from 218 finger swabs from twenty-seven men.

11. Twenty-eight faecal specimens were examined from fifty-four cases of gastro-enteritis reported on the Mediterranean cruises; salmonellae were not found, but heat-resistant Cl. welchii was isolated from six samples (21%), and the clinical picture was that of Cl. welchii food poisoning.

12. 121 faeces samples from 137 patients with gastro-enteritis were examined chiefly for salmonellae and coagulase-positive staphylococci on the outward leg of the round voyage through the tropics. Salm. typhimurium was isolated from a clinical case and Cl. welchii from one typical case of food poisoning. On the return journey all samples were examined also for Cl. welchii; of thirty-five stool samples from thirty-five patients, six (17%) yielded lecithinase-positive clostridia; salmonellae were not found.

13. Heat-resistant strains of Cl. welchii were also isolated from two chopping-boards, a knife, cold beef, brawn, two wiping cloths, a dish cover, two samples of pie and corned beef.