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.

1. Statistical evidence and animal experiment have alike proved carbolised killed anti-rabies vaccine to be of undoubted efficacy in both pre-infectional and post-infectional treatment. Statistical evidence is furnished by the results of treatment of 90,000 patients, while experimental proof rests partly on the resistance shown by immunised animals to artificial infections with street virus, and partly on an estimation of degree and duration of rabicidal properties in their sera.

2. The Bordet-Gengou reaction is of no value as a qualitative or quantitative test for the estimation of anti-rabies immunity.

3. The efficacy of killed carbolised vaccine and probably of other antirabies vaccines is largely dependent on the concentration of the dosage and the period within which it is administered. Better results follow the giving of small doses over a number of days than the giving of larger doses over a shorter period.

4. It is impossible to reduce below a certain limit the time over which the total quantity of vaccine ordinarily sufficient for complete immunisation can be usefully administered.

5. The effect on rabbits of the subcutaneous injection of fresh-fixed virus is dependent on the quantity of virus introduced and on the duration of its period of administration. Few inoculations are more likely to cause death than several; repeated inoculations ordinarily confer immunity. Immunity thus acquired must have been produced within 11 or 12 days.

Cystic echinococcosis (CE) remains an important health problem in many areas of the world, including the Mediterranean region. We performed a retrospective study of cases reported from 1998 to 2012 in order to review and update the epidemiology of this disease in a highly endemic area situated in western Spain. A total of 471 patients were diagnosed with hydatid disease. Of these cases, 55·8% were male, with an average age of 62·3 ± 19·5 years. More importantly, 1·5% of patients were children, and 20·5% were aged <45 years. An active therapeutic approach was implemented for 92·6% of the CE patients with primary diagnoses; however, a ‘watch and wait’ strategy was used in 59·3% of all secondary CE diagnoses. The incidence rate of hydatid disease was significantly higher compared to the incidence described in the Notifiable Disease System in this area. Furthermore, a significant decrease in hydatid incidence during the years included in the study was observed (β = −0·4357, P < 0·001). CE incidence has diminished in recent years, although active transmission remains in paediatric cases. Additionally, CE incidence remains high in our region despite public health plans for its control. The documented incidence of CE disease clearly underestimates the real numbers.

Although communicable diseases have hitherto played a small part in illness associated with Olympic Games, an outbreak of infection in a national team, Games venue or visiting spectators has the potential to disrupt a global sporting event and distract from the international celebration of athletic excellence. Preparation for hosting the Olympic Games includes implementation of early warning systems for detecting emerging infection problems. Ensuring capability for rapid microbiological diagnoses to inform situational risk assessments underpins the ability to dispel rumours. These are a prelude to control measures to minimize impact of any outbreak of infectious disease at a time of intense public scrutiny. Complex multidisciplinary teamwork combined with laboratory technical innovation and efficient information flows underlie the Health Protection Agency's preparation for the London 2012 Olympic and Paralympic Games. These will deliver durable legacies for clinical and public health microbiology, outbreak investigation and control in the coming years.

A combination of calciferol (vitamin D2) and warfarin, each at 0·025% in medium oatmeal bait, failed to control six of seven house-mouse (Mus musculus L.) populations infesting urban and farm buildings. In three further treatments with both calciferol and warfarin at 0·05 % in dehusked canary seed bait plus 5% corn oil, mortality, estimated from the consumption of pre- and post-treatment census bait, ranged between 94·2 and 97·4%. Finally, among sixteen treatments done with calciferol at 0·1% and warfarin at 0·025% in various cereal baits, the best results (97·0–100%) were obtained in six treatments where the bait-base was whole canary seed; this was so whether the poison bait was applied directly or after a 3-day pre-baiting period. It is concluded that calciferol at 0·1 % plus warfarin at 0·025 % is an effective combination against house-mice, especially when used with whole canary seed. The role played by warfarin in the poison mixture needs to be investigated further.

Eighty-seven cases of subacute sclerosing panencephalitis (SSPE) were diagnosed from September 1988 to April 1991 in Papua New Guinea (PNG), by demonstration of high-titre measles-specific antibodies in cerebrospinal fluid (CSF). For 1990 the annual incidence of SSPE, for the study provinces, was calculated to be 56 cases per million under 20 years of age and it is expected that this figure will be higher in 1991. The mean age of presentation was 4.9 years, with a male to female ratio of 1.8:1. An elevation in the ratio of immunoglobulin G as a percentage of total protein in CSF and an increase in the CSF:serum immunoglobulin G ratio was shown in SSPE patients. The dramatic appearance and high frequency of the disease in PNG might relate to the early age of measles infection encountered in children in this country.

Two dairy herds, situated on a sewage farm, were monitored for the presence of salmonellas following outbreaks of Salmonella dublin infection. In addition an S. dublin control scheme, which involved examination of adult animals and calf vaccination, was instigated.

During the period 1975–84, 12 salmonella serotypes and 10 phage types of S. typhimurium were isolated from the cattle and their environment although their presence was seldom associated with disease. Two adult S. dublin excreters were detected but it was concluded that none of the tests employed to examine the adult animals was sensitive enough. The prevalence of disease in the calves was low and although vaccination may have been beneficial it did not eradicate S. dublin infection. Thus S. dublin persisted in adults and calves during the 8-year period but its presence was seldom associated with disease. The results are discussed with regards the disease risk to animals from the agricultural use of sewage sludge and the public health aspects.

Injecting drug users (IDUs) account for most new HCV infections. The objectives of this study were: to estimate the force of infection for hepatitis C virus in IDUs within the interval-censoring framework and to determine the impact of risk factors such as frequency of injection, drug injected, sharing of syringes and time of first injection on the time to HCV infection. We used data from the Amsterdam Cohort Study collected in The Netherlands and focused on those individuals who were HCV negative upon entry into the study. Based on the results, the force of infection was found to vary with time of first injection. The risk of infection was higher in the first 3 years of an IDU's career, implying estimates based on single cross-sectional studies could be biased. Frequency of injection and type of drug injected were found to be highly significant predictors, whereas sharing syringes was not.

Incidents of non-specific illness associated with the consumption of oysters have highlighted the lack of published information on the bacteriology of shellfish suitable for consumption. Investigations showed that the majority of molluscan shellfish entering English markets conform to the accepted standard of less than 5 Escherichia coli/ml. tissue. The numbers of E. coli were related to the sanitary quality of the growing area but no relation could be established between numbers of E. coli and coliforms, faecal streptococci or Clostridium welchii. The numbers of non-specific bacteria varied considerably but shellfish from sources associated with non-specific illness yielded relatively high counts at 37° C. The results showed that there was no justification for a standard based on total plate counts, which often exceeded 106/g. Such a standard would have to be coupled with spoilage or the incidence of non-specific illness. The relation between the numbers of non-specific bacteria growing at 20 and 37° C. appears to be a useful measure for assessing the likelihood that raw shellfish are a public health risk.

1. The disease is an acute encephalo-myelitis produced by a virus akin to, but not identical with, that of the Heine-Medin disease.

2. The disease was readily communicated, with fatal results, to monkeys (Macacus rhesus) by intracerebral inoculation of a suitably-prepared emulsion of nervous substance (brain, cerebellum, pons, medulla and spinal cord) from the human subject dead from “X disease.” Moreover, the virus was found to breed true in a succession of thirteen monkey (Macacus rhesus) generations.

3. The disease was not communicated to Macacus cynomolgus (several trials).

4. The disease was communicated by the above-mentioned method from monkey to sheep (10 times), from sheep back to monkey and on again from monkey to monkey.

5. A certain number of sheep, perhaps 50 per cent., were found wholly insusceptible to the disease; others suffered lightly and recovered.

6. The disease was communicated, with fatal results, by the same method, from monkey to horse (1 case) and to calf (1 case). Two calves suffered lightly after intracerebral inoculation of the usual virus-containing material taken from monkey and horse respectively.

7. The virus appears to be held back completely, or to a great degree, by the pores of a Berkefeld filter.

8. Storage of the virus-containing material in diluted glycerine, under cool conditions, for longer than a few days, reduced or annulled its nocive properties.

9. Drying of the virus-containing material in Petri dishes, in an incubator, probably destroys its activity.

10. In the case of the sheep, there was failure to induce the disease by swabbing the nostrils with virus-containing emulsion.

11. There is some evidence that in the case of the sheep and the calf a previous inoculation with the virus confers immunity.

12. One experiment suggested that artificial immunity might be induced in the monkey by inoculation of virus treated with serum from an “X disease” sheep.

13. Intracerebral inoculation of three dogs, one kitten, two rabbits and one hen failed to produce any signs of the disease; and similar inoculations of two guinea-pigs gave doubtful results.

14. Treatment of the virus-containing emulsion with (a) normal human serum, (b) serum from recovered human cases of “acute poliomyelitis” and (c) serum from “X disease” sheep prolonged the incubation period of the disease in the monkey but did not destroy the virus.

15. Normal sheep serum and serum from “X disease” sheep did not neutralise the virus in its operation on other sheep.

16. Two experiments suggested that the virus was no longer present in the monkey on the eighth or tenth day of illness.

17. Two experiments towards the end of the investigation suggested a waning in strength of the virus.

18. Intraperitoneal and intrasciatic inoculations of virus-containing material, also intracerebral inoculations of cerebro-spinal fluid, of a filtrate of faeces, of a “Noguchi culture,” of an emulsion of fowl ticks, of naso-pharyngeal swabs from human cases and contacts, and inoculations into veins, all failed.

Since its development in 1988, a serologic typing scheme for Xanthomonas maltophilia, based on 31 O antigens, has been successfully used to serotype isolates involved in nosocomial outbreaks in the United States. To determine if this serotyping scheme would be useful in typing X. maltophilia isolates from worldwide sources, we obtained additional isolates from 10 countries; of 900 isolates tested, 795 (88·3%) were typable. In order of predominance, the three most common serotypes were 10, 3 and 19. These three serotypes were most frequently associated with respiratory and blood isolates. This serotyping system is useful as an epidemiologic screening method for universal typing of outbreaks of X. maltophilia infections.

A prospective study identified 785 pregnant women who had been shown to possess complement fixing antibodies against cytomegalovirus (CMV) during a previous pregnancy. As these women were thus known to have been immune prior to their subsequent conception, their neonates were examined for evidence of congenital CMV infection. Specimens were obtained from 725(92%) of the neonatcs and congenital infection was found in only one (0·14%). The elder sister of the infected child was also shown, by retrospective testing of her stored cord serum for specific IgM antibodies, to have been infected in utero. Thus, one woman was identified who had delivered consecutive siblings congenitally infected with CMV. We conclude that some women have a propensity for intra-uterine transmission of CMV, despite being immune prior to conception, and speculate that such women may have acquired their infections perinatally.

1. Feeding tests on monkeys (Macacus rhesus), dogs and cats are unsatisfactory for detecting the presence of enterotoxin, owing to the variable susceptibility of these animals by the oral route.

2. Using Dolman's method, in which the material is injected intra-peritoneally into kittens, the production of enterotoxin has been demonstrated by: (a) sixteen out of thirty-eight strains of Staph. aureus, isolated from cases of acute or chronic mastitis or from normal udder milk; (b) four out of five strains of Bact. coli, mostly from calves with “white scours”. No enterotoxin was obtained from fifteen strains of Str. agalactiae from mastitis in cows.

3. The formation of enterotoxin under natural conditions has been observed: (a) In udder milk seeded with Staph. aureus or naturally contaminated with that organism and stored at atmospheric temperatures (18 and 22°C.). The substance remains active in cheese prepared from such milk. (b) In layer cake made with cream naturally contaminated with Staph. aureus.

4. A small outbreak of poisoning due to potted meat paste was shown to be caused by a non-haemolytic Staphylococcus.

5. A few feeding experiments on man with milk or cream, in which food-poisoning staphylococci had grown, were negative, but on one occasion a Staphylococcus from a case of mastitis yielded a culture filtrate which caused symptoms of food poisoning.

6. Enterotoxin has the following properties. It is resistant to heat (95°C., 30 min.), to low concentrations of formalin sufficient to destroy the haemolytic toxin, to acid (pH 5·0), and to rennet, but is destroyed by trypsin.

It diffuses freely into the culture medium but only slightly through collodion. It is antigenic. Its properties are such that enterotoxin can be classed as a bacterial exotoxin.

The results of serotyping of 10953 salmonella isolates from humans over a 10-year period, 1973–82 at the Bacteriology Division, Institute for Medical Research, Malaysia are presented. A total of 104 serotypes from 22 ‘O’ groups were encountered; 95 isolates were considered untypable. The three most predominant serotypes, namely Salmonella typhi, S. typhimurium and S. weltevreden together accounted for 54·1% of all isolates whilst the 25 most frequent serotypes accounted for 93·6% of the total. Whilst the commoner serotypes occurred regularly throughout the study period, the rarer ones tended to appear only in one year, when they might be associated with an outbreak, and never again.

The pattern of serotypes, though quite similar to the one seen in neighbouring Singapore, is different from those experienced in other places such as Hong Kong, Jakarta, Bangladesh and Manchester.

1. Explants of embryonic chick tissue were infected with avian tubercle bacilli of different degrees of virulence to study (a) some of the factors on which control of infection in tissue cultures depends and (b) the viability of bacilli ingested by wandering cells.

2. Embryonic lung cultures could control infection for 2–3 weeks owing to the intense phagocytic activity of the many wandering cells which they contained. The tissue appeared unharmed by infection with bacilli of either virulent or avirulent strains.

3. The wandering cells largely protected the much less phagocytic fibroblasts from intracellular infection.

4. This protective action of wandering cells towards less phagocytic cell types was limited by three factors: (1) the density of the infection relative to the volume of the explant, (2) the growth-rate of the infecting strain and (3) the proportion of wandering cells which the tissue contained.

5. Even under the most favourable conditions control of bacillary growth in the tissue was only temporary, largely owing to the gradual disappearance of the wandering cells during repeated subcultivation.

6. As control of bacillary growth was lost, the lung fibroblasts became packed with bacteria, but they appeared undamaged and might even undergo normal mitotic division. Eventually the ingested bacilli seemed to kill the cells by proliferating until they burst the cytoplasm.

7. Embryonic avian tissue cultures though infected with a highly virulent strain never showed the rapid, widespread necrosis observed by Maximow in cultures of adult rabbit tissue infected with a virulent bovine strain. Possible explanations of this disparity are discussed.

8. A special method was devised for testing the viability of bacilli phagocyted by macrophages. It showed that phagocyted bacilli, whether virulent or avirulent, survived for at least 21 days; when the host wandering cells were killed the ingested organisms were capable of immediate and profuse growth on suitable nutritive medium.

Extensive surveillance for classical scrapie has been carried out in Great Britain since 1993, the results of which can be used for monitoring the effect of control measures introduced since 2001. A back-calculation approach was used to estimate the prevalence of sheep infected with classical scrapie, which integrates data on reported clinical cases (1993–2007) and the results of fallen stock and abattoir surveys (2002–2007). The prevalence of classical scrapie in GB was fairly constant until 2003, although the estimates depended on assumptions made about the performance of diagnostic tests used in the surveys. If infected animals could be detected in the final quarter of the incubation period, the estimated prevalence was 0·6–0·7%, while if they could be detected in the final half of the incubation period, it was 0·3–0·4%. Between 2003 and 2007 the prevalence declined by around 40%, and the magnitude of the reduction was independent of assumptions made about the diagnostic tests.

A total of 100 tropical aquaria from six pet shops were sampled for the presence of Salmonella, Campylobacter and Aeromonas species. Eight fish tanks contained unusual serotypes of salmonella. None had been used to house terrapins. One hundred and three isolates of Aeromonas species were obtained from 98 tanks. One tank contained Plesiomonas shigelloides. No Campylobacter species were isolated. It is suggested that a tropical aquarium may constitute an infection hazard.

Of the large number of experiments recorded by Penfold (1914) in connexion with the question of lag in bacterial growth, a certain proportion have been carried out in such detail as to render them eminently suitable for mathematical analysis. In all work of this kind, which is intended to throw light on the numerical aspect of bacterial growth, it is desirable to take observations at frequent and, if possible, regular intervals, during the period of lag, and to count a sufficiently large number of colonies on the plates. To secure this last and most important desideratum, orientating experiments must be performed, from the results of which one is enabled to calculate what dilution of the culture at any given period of growth will yield a tolerably large and accurately countable plate population.

The parasite Echinococcus multilocularis was first detected in The Netherlands in 1996 and repeated studies have shown that the parasite subsequently spread in the local population of foxes in the province of Limburg. It was not possible to quantify the human risk of alveolar echinococcosis because no relationship between the amount of parasite eggs in the environment and the probability of infection in humans was known. Here, we used the spread of the parasite in The Netherlands as a predictor, together with recently published historical records of the epidemiology of alveolar echinococcosis in Switzerland, to achieve a relative quantification of the risk. Based on these analyses, the human risk in Limburg was simulated and up to three human cases are predicted by 2018. We conclude that the epidemiology of alveolar echinococcosis in The Netherlands might have changed from a period of negligible risk in the past to a period of increasing risk in the forthcoming years.

We investigated the distribution of comorbidities among adult tuberculosis (TB) patients in Chiapas, the poorest Mexican state, with a high presence of indigenous population, and a corridor for migrants from Latin America. Secondary analysis on 5508 new adult TB patients diagnosed between 2010 and 2014 revealed that the most prevalent comorbidities were diabetes mellitus (DM; 19.1%) and undernutrition (14.4%). The prevalence of DM in these TB patients was significantly higher among middle aged (41–64 years) compared with older adults (⩾65 years) (38.6% vs. 23.2%; P < 0.0001). The prevalence of undernutrition was lower among those with DM, and higher in communities with high indigenous presence. Immigrants only comprised 2% of all TB cases, but were more likely to have unfavourable TB treatment outcomes (treatment failure, death and default) when compared with those born in Chiapas (29.5% vs. 11.1%; P < 0.05). Unfavourable TB outcomes were also more prevalent among the TB patients with undernutrition, HIV or older age, but not DM (P < 0.05). Our study in Chiapas illustrates the challenges of other regions worldwide where social (e.g. indigenous origin, poverty, migration) and host factors (DM, undernutrition, HIV, older age) are associated with TB. Further understanding of these critical factors will guide local policy makers and health providers to improve TB management.