A village epidemic of brucellosis, due to Brucella melitensis, contracted from infected sheep and goats owned by the vifiagers is described. Of the 309 inhabitants eighty-four became infected and seventy-nine were clinically ill with brucellosis. The investigation covered 232 of the total population and nearly all those not examined belonged to the age group, 0–5 years, not directly exposed to infection by contact with diseased animals.

The population of the village was made up of forty-six families, only nine of which escaped infection. In the affected families, the incidence varied from one to seven in each case. The size of the family varied from three to eleven but there was no correlation between the size of the family and the number contracting brucellosis, neither did sex play any part in the incidence. All age groups were susceptible but the morbidity increased with age and this was correlated with increased risk of exposure to infection of the older age groups.

There was considerable variation in the severity of the clinical illness but there were no fatiities and all patients responded to antibiotic therapy.

Brucella melitensis was isolated from twenty-eight of the thirty-six patients subjected to blood culture and specific agglutinins at an acceptable level were demonstrated in all but three of those with a clinical illness.

The number of persons without evidence of clinical brucellosis who possessed significant brucella agglutinins was very small and the assumption that in an endemic area the number of infected persons is much greater than the number clinically ill was not borne out in the outbreak described here.

Persistence of specific agglutinins up to 2 years after recovery from the clinical illness is recorded.

We wish to pay tribute to the late Professor J. Gurevitch for his constant interest and helpful advice.

Thanks are due to Prof. M. Ruiz Castaneda for providing us with the Castaneda bottles for blood culture work, to Dr E. Neeman of the Government Brucella Reference Laboratory for supplying the Standard Brucella Antigen and for examining the strains of Brucella isolated, and to Colonel H. J. Bensted for his interest and help in preparing the paper. Finally, we are indebted to Mrs Aliza Abut Kayner, social worker in the village health centre, for her valuable help in gathering statistical data.

The virulence of strains of the three types of poliovirus have been examined by the subcutaneous injection of monkeys. The strains used were the Sabin attenuated Types 1, 2 and 3, Cox attenuated Types 1, 2 and 3, the Brunenders Type 1 partially attenuated strain, MEF-1, Type 2 and Saukett, Type 3.

The results obtained indicated that the subcutaneous route of injection offers a promising method for comparing and characterizing strains of poliovirus.

1. Two methods of injecting monkeys intraspinally are compared.

2. It has been shown that the technique of inserting the needle through the cord and withdrawing it 1–2 mm. before injection (Sabin's technique) gives a less widespread distribution of inoculum than the alternative method of making the injection as soon as the tip of the needle is within the substance of the spinal cord (‘standard technique’).

3. When attenuated Type 3 poliovirus is injected into cynomolgus monkeys by Sabin's technique, the incidence of paralysis and poliomyelitis lesions observed is less than when it is injected by the ‘standard technique’.

4. The relative merits of the two techniques are discussed.

By means of a complement-fixation test of the sera of laboratory rats and mice, the immunological response of these animals to both naturally occurring and induced PPLO infections was determined, and the presence and extent of infection in the animals determined by culture.

PPLO antibodies specific for the infecting strain were demonstrable in rats and mice from which PPLO were isolated.

The amount of serum antibody rises with the extent and severity of the infection. Thus, young rats with PPLO infections confined to the nasopharynx had little or no antibody whereas the oldest rats with consolidated lungs had the highest titres. In mice too, the sera of those with pneumonia had the highest titres.

The comparatively low titres found in rat bronchiectasis together with the failure to isolate PPLO from the spleen and other organs, suggest that the chronic form of the disease remains localized. This is in contrast to infections with rat polyarthritis and related PPLO in which the organisms can be isolated from the lymph nodes and other organs and in which antibody is present in high titre.

In view of the high degree of correlation between the presence of antibodies to PPLO in the blood and the presence of PPLO in the tissue of rats and mice, it is suggested that specific antibody found in man is a significant indicator of PPLO infection.

1. Field trials suggest that 3-monthly operations against rats in sewers using either 0·25% sodium fluoracetate or 2% fluoracetamide as a direct poison are more effective than 6-monthly treatments with 2·5% zinc phosphide or 10% arsenious oxide using the pre-baiting method.

2. In six paired trials 2% fluoracetamide gave better results (an apparent 100% clearance in five instances) than 0·25% sodium fluoracetate.

3. There is no evidence, at present, that direct poisoning treatments with 2% fluoracetamide or 0·25% sodium fluoracetate are improved by the addition of mould inhibiting substances to the bait.

The work described above was made possible only by the co-operation of a large number of local authority councils and their staffs, to whom we are therefore much indebted. We wish to thank also, Mr J. D. Riley who gave considerable help during the early stages of the trials.

An investigation is reported into sepsis due to Staphylococcus aureus in the maternity unit of a provincial hospital and in domiciliary midwifery in the same town.

In the hospital Staph. aureus infections of mother or infant occurred 123 times per 1000 live births in one ward and 116 per 1000 in another, but the use of hexachlorophane powder on the infants in one ward reduced the sepsis rate in that ward to 34 cases per 1000 live births, thus confirming the reports by two teams in Bristol hospitals. Sepsis was more frequent in both mothers and infants after Caesarean delivery than after normal labour. Reasons are given for thinking that ‘sticky eyes’ are usually not caused by the bacteria isolated when the eyes are swabbed.

The rate of infection in domiciliary cases was 39 per 1000 live births. As all these were normal deliveries the sepsis rate cannot be directly compared with that occurring among complicated cases in hospital.

No evidence was found that hospital Staph. aureus strains carried home by newly born infants were causing a significant amount of sepsis among their home contacts within 28 days of delivery.

The importance of nurses as sources of infecting strains of Staph. aureus in maternity work is discussed. The infant-to-infant route of transmission has been stressed in the literature but reasons are given for believing that nurse-to-infant infection in the labour room may also be important under certain circumstances.

I am greatly indebted to Dr V. P. Randall Martin, formerly Senior Medical Officer in the Hampshire County Health Department, who organized the follow-up of patients after leaving hospital and after home delivery, and also to the County Medical Officer Dr I. A. MacDougall for his help.

I am also grateful to Messrs P. R. Mitchell and G. T. Hammond for permission to investigate their wards and to Sister D. M. Carter and her staff, and to the County midwives and Health Visitors, for their co-operation.

Dr G. J. G. King kindly undertook the phage-typing of a large number of strains of Staph. aureus at the Bournemouth Public Health Laboratory, for which I am most grateful.

I am also grateful to Dr W. A. Gillespie for information in advance of publication, and for advice, about the hexachlorophane regimen of which he and his Bristol colleagues were the pioneers.

1. This paper confirms and extends several observations during the past 20 years that, despite many reports to the contrary, the rat is not unduly resistant to initial infection with tubercle bacilli provided they lodge in the lungs.

2. The pattern of pathogenesis in the rat is probably closest to the now classical picture in the mouse, i.e. the response of a species with a low hypersensitivity potential. The pathology of the lesions agreed closely with the descriptions of Wessels (1941) and Kumashiro (1958b) resembling the mouse in most respects but, unlike the mouse, including the production of giant cells.

3. When tested by footpad inoculation with 1/3·5 Old Tuberculin a positive reaction was demonstrated, commencing between 2 and 5 weeks after infection and persisting for several weeks. A fatal systemic reaction could often be induced with large doses of tuberculin given intraperitoneally.

4. In a few cases loss of allergy was shown to be associated with a terminal anergic flare of the type observed previously in mice and guinea-pigs.

1. An H.A.I. test for louping ill in sheep is described and its potentiality investigated alongside a standard C.F. test.

2. Sheep free from infection with, or which have not been vaccinated against, louping ill do not possess serum antibody demonstrable by the C.F., H.A.I. or neutralization techniques as described here.

3. After the administration of commercial vaccine followed by infective virus, C.F., H.A.I. and neutralizing antibodies are detectable. The C.F. antibodies are the least stable and in many instances disappear entirely from the peripheral circulation within 4 months of their appearance; they also appear to be susceptible to fluctuation unassociated with the disease. H.A.I. antibodies elicited under the same circumstances reach a high level early, are maintained for longer periods than C.F. antibodies, and fall to a basic level which tends to be maintained.

4. H.A.I. antibodies do not appear to be elicited in response to inoculation with vaccine only, in contrast to C.F. and neutralizing antibodies which are so elicited. It is suggested in these circumstances, measurement of H.A.I. antibody is the most useful of the serological tests available for surveys and for diagnostic purposes in sheep.

We wish to thank Mr A. Sharman, B.Sc., M.R.C.V.S., formerly of the North of Scotland College of Agriculture, Aberdeen, under whose care and supervision the flock was maintained and who inoculated and bled the animals.

We are particularly indebted to Dr C. E. Gordon Smith, of the London School of Hygiene and Tropical Medicine, for valuable criticism and advice.

A total of 375 separate sampling experiments were performed on groupings of 100 samples each from distinct binomial populations in order to obtain estimates of the frequency of rejection of the hypotheses of homogeneity against alternatives of a trend by means of the usual χ2 or binomial index of dispersion test. These artificial realizations are presented in Figs. 1–5, and compared graphically with corresponding non-central χ2 distributions.

The authors would like to acknowledge the technical assistance of the Research Computer Laboratory of this University in programming and supervising the computational phases of this investigation, which was partially supported by the State of Washington Initiative 171 Funds for Research in Biology and Medicine and the Boeing Employees' Good Neighbor Fund.

The ‘ceiling temperature’ of a pox virus has been defined as the maximum temperature (to the nearest 0·5° C.) of incubation at and below which that virus will grow and produce pocks on the chorioallantois of 12-day-old chick embryos, and above which no pocks appear.

Ceiling temperatures have been estimated for: alastrim (2 strains), 37·5° C.; variola major (2 strains), 3·8° C.; ectromelia (3 strains) and monkey pox (1 strain), 39°C.; cowpox (2 strains), 40°C. Five strains of vaccinia and two of rabbit pox were all capable of pock formation at 40·5° C. Above this temperature difficulty was encountered because many embryos died. But the ceiling temperature for two strains of vaccinia and one strain of rabbit pox was probably 41° C. The Utrecht strain of rabbit pox produced some lesions at 41·5° C.—the highest temperature used.

The ceiling temperatures of the viruses used were not correlated with their thermal stabilities at 55°C. in vitro. Thus vaccinia strain, Lederle-7 N, had a high ceiling temperature and a low thermal stability, while variola major had a low ceiling temperature and a high thermal stability. For this reason ceiling temperatures and thermal stability are regarded as distinct characters.

In experiments with twelve of the seventeen viruses of which the ceiling temperatures had been determined, the virulence for the chick embryo was then measured. It was found that, in general, the higher the ceiling temperature of a virus the greater was its virulence for the chick embryo.

The presentation of these results is followed by a brief discussion of their significance and potential use.

1. Wistar-albino rats showed no significant difference from albino mice in their response to pulmonary tuberculosis. This conclusion was reached after a detailed comparison of bacillary multiplication, lung involvement, death rates and the rate of conversion to the immune state as determined by footpad reaction to tuberculin in the two species.

2. These findings support the theory that the key to species differences in resistance to tuberculosis is the rate of onset of acquired immunity and it is therefore unrelated to natural resistance.

Airborne virus particles of vaccinia, influenza, Venezuelan equine encephalomyelitis, and poliomyelitis have been tested for viable survival in the dark at controlled temperatures and relative humidity (R.H.) for up to 23 hr. after spraying.

Viable survival at each R.H. level was better at lower temperature than at higher temperature. Poliomyelitis virus showed best survival at high R.H.; the other three viruses survived best at low R.H.

Three tubular electrostatic precipitators are described for the assay of bacterial and bacteriophage aerosols. Particles can be sampled directly on agar or on agar-impregnated paper in a wide range of aerosol concentrations, or sampled into a fluid for the assay of airborne micro-organisms. Rapid consecutive sampling is possible with the samplers and a collection efficiency approaching 100% is readily obtained. Their sampling efficiency is compared with that of the slit sampler and the liquid impinger.

The infectivity of Pasteurella tularensis clouds decreases with age, for guineapigs challenged by the peritoneal and respiratory routes. No decrease occurs in mice challenged peritoneally. The loss of infectivity depends to some extent on age of culture but more especially on culture medium used. Cultures grown in a partially hydrolysed casein medium and aged 2–3 weeks lose infectivity severely in clouds held 20 hr. at 85% r.h., whereas if grown in cysteine broth with catalase (CBC) no loss occurs in this time until cultures are aged several months. Chloride ion, yeast extract and casein hydrolysate are shown to be infectivity depressors when used in culture media or when added to suspensions before spraying. Sodium chloride in CBC can be replaced adequately by sodium sulphate or sodium phosphate for growth of the organism.

The literature on the dissemination of helminth ova by flies is reviewed. In experiments using various species of filth flies, it was shown that ova of Taenia saginata Goeze 1782 can be passed out for periods of up to 11 days after ingestion, and viability of such ova was demonstrated for three days after ingestion. The possible methods of dissemination of ova are discussed together with the longevity of ova on pasture and the dispersal habits of flies. It is suggested that in Kenya, filth flies may play an important role in the epizootiology of bovine cysticercosis.