Guinea-pigs are usually mated in permanent polygamous groups, one or more males with a large number of females, the young being harvested when ready to wean. This system is economical of labour, and is efficient in allowing of mating at post-partum oestrus and therefore of maximum reproductivity. There are, however, serious disadvantages; it is difficult to keep track of individual performance and difficult therefore to eliminate unproductive sows, the ancestry and exact age of the young are often unknown, and the conditions of rearing young among a crowd of adults are probably not ideal. These considerations suggest that, given high-grade breeding stock, the polygamous system is adequate, and probably inevitable, for the mass production of young for experimental purposes, but that it leaves much to be desired for the production of breeding stock. The obvious solution of this difficulty is to maintain a large polygamous and anonymous colony for mass breeding, and, quite separately, a small closely recorded colony to supply the breeding animals. A goodsow should produce at least 10 young per year in a life of 2 years. A demand of 10,000 animals per year, for experimental work, therefore requires a mass-breeding stock of 1000 sows, an annual replacement of 500 sows and a stock-breeding stock of 100 sows. According to our experience, about 2 hr. daily on the part of a trained technician would be required to maintain close recording of such a pilot stock and of its progeny to puberty (Bruce & Parkes, 1947b).

A comparison of homologous and heterologous rates of neutralization demonstrated that antigenic relationships of foot-and-mouth disease virus strains could be differentiated quantitatively by the kinetics of neutralization method described previously (Rweyemamu, Booth & Pay, 1977). Conventional formulae for r, R and D values could be applied to results obtained by this method. It was demonstrated that results analysed this way gave R values which were similar to those obtained with other neutralization test methods but which were generally smaller than those obtained with complement fixation test results. It was demonstrated that there were wide differences between the vaccine strains tested as demonstrated by R value relationships. An examination of r values, however, demonstrated that antisera to the Moz 1/70 strain were highly reactive with most of the virus strains from Central and Southern Africa. The selection of FMD virus strains with a wide serological range for vaccine production is discussed.

1. The virulence of S. typhi strains Ty 2 and O 901 injected intra-abdominally into white mice was examined. The lethal dose of strain Ty 2 grown in vivo was lower than that of the corresponding culture grown in vitro, while the lethal doses of the in vivo- and in vitro-grown strain O 901 were almost identical.

2. The extracts of infected livers and spleens were not toxic, but acted as infection-promoting substances. Extracts from normal organs exerted similar but weaker effects. Glycogen together with sodium taurocholate were powerful infection-promoting substances. The highest increases of virulence were observed when spleen-grown bacteria together with extracts from infected organs were injected.

3. Extracts from infected spleen, pancreas, stomach and lower intestines, spleen-grown S. typhi, other spleen-grown Enterobacteriaceae, and bacteria taken from the intestines of normal and diseased animals, exhibited high DPN-ase activity.

4. The extracts from infected organs contained soluble bacterial antigens. Their presence was demonstrated by tube precipitation, agar gel precipitation and antibody production after immunization of rabbits with extracts from infected organs with addition of adjuvants.

5. Spleen-grown bacteria were able to absorb host antigens and to produce, in addition to the known agglutinating antibodies, anti-spleen precipitins.

The objective of this study was to determine how clinicians make use of the modern multiplex PCR assays (MPAs) to manage patients hospitalized for community-acquired pneumonia (CAP). We studied the use of MPAs in 1648 patients hospitalized for CAP over a 3-year period at the moment of the setup of the new PCR assay. We observed that the use of MPAs for the identification of multiple respiratory pathogens marks a radical change in the investigation of CAP etiology. Surprisingly, the contribution of MPAs to the medical decision-making process varies drastically according to the units of care.

From an outbreak of very mild “typhus-like disease” in Pretoria, which strongly resembled the cases of “sporadic” or “mild” typhus occasionally occurring in that town, a virus was isolated which was studied in guinea-pigs and rabbits, and was found to belong to the typhus-group.

This virus in cross-immunity experiments with virus of South African louse-typhus and South African tick-bite fever and also in other respects behaved exactly like the typhus-like virus the authors on a previous occasion isolated from rats in a South African town where cases of “mild” or “ sporadic ” typhus have been known to occur regularly for many years.

This constitutes evidence that South African “mild” or “sporadic” typhus comes from rats and is communicated to man by rat-fleas.

In southern Africa, therefore, one has to reckon with three typhus-like diseases: tick-bite fever, flea-typhus from rats, and louse-typhus. Tick-bite fever has a primary sore, the tick-bite, as a pathognomic symptom, the other two can only be differentiated satisfactorily from one another by cross-immunity tests.

Agglutination reactions and cross-immunity tests show that South African louse-typhus and South African rat- or flea-typhus are not identical with similar diseases in other parts of the world.

Tick-bite fever is a mild typhus-like disease extending from the Cape to South Rhodesia.

The typhus-like disease of Kenya is not tick-bite fever, and seems to be identical with fièvre boutonneuse.

The investigations described in the present paper were undertaken during the summer of 1902, at the request of the Select Committee on the Ventilation of the House of Commons.

We used data from BioSense, a national electronic surveillance system, to describe pneumonia in hospitalized patients with influenza-like illness (ILI). Ninety-five hospitals from 20 states reported ICD-9-CM-coded inpatient final diagnosis data during the study period of September 2007 to February 2010. We compared the characteristics of persons with and without pneumonia among those with ILI-related hospitalizations. BioSense captured 26 987 ILI-related inpatient hospitalizations; 8979 (33%) had a diagnosis of pneumonia. Analysis of trends showed highest counts of pneumonia during the 2007–2008 season and the second 2009 pandemic wave. Pneumonia was more common with increasing age. Microbiology and pharmacy data were available for a subset of patients; 107 (5%) with pneumonia had a bloodstream infection and 17% of patients were prescribed antiviral treatment. Our findings demonstrate the potential utility of electronic healthcare data to track trends in ILI and pneumonia, identify risk factors for disease, identify bacteraemia in patients with pneumonia, and monitor antiviral use.

Knowledge, attitudes and practices (KAP) of the population regarding severe fever with thrombocytopenia syndrome (SFTS) in endemic areas of Lu'an in China were assessed before and after an intervention programme. The pre-intervention phase was conducted using a sample of 425 participants from the 12 selected villages with the highest rates of endemic SFTS infection. A predesigned interview questionnaire was used to assess KAP. Subsequently, an intervention programme was designed and applied in the selected villages. KAP was re-assessed for each population in the selected villages using the same interview questionnaire. Following 2 months of the programme, 339 participants had completed the re-assessed survey. The impact of the intervention programme was evaluated using suitable statistical methods. A significant increase in the KAP and total KAP scores was noted following the intervention programme, whereas the proportion of correct knowledge, the positive attitudes and the effective practices toward SFTS of respondents increased significantly. The intervention programme was effective in improving KAP level of SFTS in populations that were resident in endemic areas.

Using a laboratory downward displacement vertical autoclave with the help of thermocouples recorded on a 12 point multichannel strip recorder, the risk of failing to sterilize laboratory discard buckets has been demonstrated. The use of proper temperature and time controls can prevent this risk.

A load in a bucket with perforated sides is more easily sterilized than in a solid bucket. Wire baskets, where appropriate, facilitate the sterilizing practice. The addition of water to a bucket does not reduce the time of heating up.

It is desirable that sealed bottles of media should not be sterilized in simple downward displacement autoclaves, but if used, strict monitoring of temperatures and times is essential both in the heating up stage and especially in the cooling stage. The temperatures in bottles are slow to rise and very slow to fall. Bottles at high temperature 80–405° C. or over have a high internal pressure which can allow the bottles to explode when subjected to thermal shock if removed too early.

It is suggested that all laboratory autoclaves should have a load temperature simulator or similar device to control the temperature of the load during the cycle automatically. For the sterilization of fluid media, it is suggested that, in addition to a simulator there should be accelerated cooling to reduce damage to the media and, what is more important, to rapidly bring down the temperature and thus the internal pressure in the bottles to a safe level. The opening of the sterilizer door or lid should be automatically controlled by the load temperature simulator.

Osmotic injury in frozen-thawed T4 phage was caused by the sudden and large fall in the electrolyte concentration of the unfrozen aqueous phase during rapid thawing of frozen samples. In accordance with the classical interpretation of osmotic shock it was found that DNA was quantitatively liberated from T4 phage inactivated by the osmotic injury of rapid thawing.

The degree of inactivation of osmotically shocked T4 phage was temperature dependent, being much increased by lowering the temperature, but was independant of the pH of the suspending medium. The T4Bo osmotic shock-resistant phago was refractory to the osmotic injury of rapid thawing.

Tick-borne encephalitis is a serious arboviral infection with unstable dynamics and profound inter-annual fluctuations in case numbers. A dependable predictive model has been sought since the discovery of the disease. The present study demonstrates that four superimposed cycles, approximately 2·4, 3, 5·4, and 10·4 years long, can account for three-fifths of the variation in the disease fluctuations over central Europe. Using harmonic regression, these cycles can be projected into the future, yielding forecasts of sufficient accuracy for up to 4 years ahead. For the years 2016–2018, this model predicts elevated incidence levels in most parts of the region.

The relationship between chickenpox and yaws epidemics occurring among children in a village in Netherlands New Guinea is analysed using the mathematical model for a simple deterministic epidemic. It is shown that the yaws epidemic accelerated significantly in the month following the chickenpox epidemic, but that it reverted to its previous rate in the succeeding months. The number of yaws cases attributable to the influence of the chickenpox is estimated from the projected course of the yaws epidemic. It is statistically verified that those children contracting chickenpox were more likely to become yaws cases in the subsequent month.

These results point to the danger of yaws's spread being much more rapid among a population which has recently been subject to an epidemic of chickenpox.

Most air disinfectants fail at low relative humidity. Those which remain active appear to be the same compounds which, in other circumstances, can protect living cells against the lethal damage caused by freezing to low temperatures and then thawing. The compounds are either simple glycols, whose respective activities in the two fields are already known, or the weaker Lewis bases, whose air disinfectant properties have not hitherto been investigated. It is suggested that both freezing protection and bactericidal action are due to the special solvent properties of these compounds, which come into play when most of the water usually present has been removed, by freezing or by drying respectively.

I am indebted to Dr 0. M. Lidwell for the loan of air sampling equipment, and to Dr L. N. Owen and to the Shell Chemical Co. for the gift of various diols.

A total of 193 sera were examined for antibody to Mycoplasma pneumoniae by three techniques – complement fixation (CF), haemagglutination (HA) and immunofluorescence (IF), the last method being used to assess IgM, IgG and IgA antibodies. The most reliable single test for diagnosis was HA, and the most useful combination of tests was HA with IF (IgM and IgG). The IgA IF was not found to be diagnostically helpful.

Hospital infections caused by strains of Staphylococcus aureus non-typable (NT) by phages have occurred in three Spanish hospitals since 1981. Reverse typing allowed characterization of the strains in all three cases.

In the present lecture I shall have to go back to the very beginning of modern knowledge on malaria. I shall incur grave risks of telling you things you know already; as a matter of fact, it is more than a risk, it is a certainty. But I cannot help myself. All I can do is to pass over the initial stages as summarily as possible.

The study of the bacteria of natural waters is dependent on a simple and effective sampling technique. Any routine sampling procedure designed to obtain a vertical series of samples at one station must not only exclude any possibility of contamination of the sampling vessel and its contents while it is lowered to, and raised from, the depth at which the sample is taken, but must also be capable of straightforward operation on a boat or ship under rough conditions. The sampling vessels should be of a standard, interchangeable and robust pattern, and their preparation and sterilization should be a matter of simple routine. It should be possible to use them repeatedly and they should be of sufficient capacity to permit physical and chemical as well as a bacteriological examination of the sample.

Unadsorbed, regular production pertussis vaccine was treated with polymyxin B sulphate at concentrations of 25,50 and 100 μg/ml. The toxic activity of treated and untreated vaccines was compared using both the limulus amoebocyte lysate test and the mouse-weight-gain test. Protective efficacy was also assessed by the mouse protection test. No discernible effect on either toxicity or efficacy of the pertussis vaccine was observed. When the vaccine was treated with 5000 μg/ml of polymyxin, endotoxic activity assessed by the limulus lysate test appeared to be abolished.

A total of 123 drug-resistant and drug-sensitive Shigella flexneri types 1–6, and their Escherichia coli K12 transconjugants were used for plasmid profile analysis by agarose gel electrophoresis. Resistance factors (R-factors) were further characterized by incompatibility testing.

The overall distribution of small plasmids in S. flexneri showed that a cryptic plasmid of about 4·6 Kb was found in all serotypes, and a plasmid of about 4·2 Kb was found in serotypes 1–4. Shigella flexneri types 2, 4 and 6 showed a 6·5 Kb plasmid which correlated with SSu-resistance. All S. flexneri serotypes harboured large plasmids of about 217 Kb. Plasmid profile analysis of S. flexneri in Ethiopia showed a high degree of uniformity within individual serotypes. However, there was a limited variability which, at times, could be useful for epidemiological investigation. Shigella flexneri serotypes 1–6 harboured resistance plasmids with diverse molecular weights but mostly belonging to incompatibility groups N and X.

Human infection with antimicrobial-resistant Campylobacter species is an important public health concern due to the potentially increased severity of illness and risk of death. Our objective was to synthesise the knowledge of factors associated with human infections with antimicrobial-resistant strains of Campylobacter. This scoping review followed systematic methods, including a protocol developed a priori. Comprehensive literature searches were developed in consultation with a research librarian and performed in five primary and three grey literature databases. Criteria for inclusion were analytical and English-language publications investigating human infections with an antimicrobial-resistant (macrolides, tetracyclines, fluoroquinolones, and/or quinolones) Campylobacter that reported factors potentially linked with the infection. The primary and secondary screening were completed by two independent reviewers using Distiller SR®. The search identified 8,527 unique articles and included 27 articles in the review. Factors were broadly categorised into animal contact, prior antimicrobial use, participant characteristics, food consumption and handling, travel, underlying health conditions, and water consumption/exposure. Important factors linked to an increased risk of infection with a fluoroquinolone-resistant strain included foreign travel and prior antimicrobial use. Identifying consistent risk factors was challenging due to the heterogeneity of results, inconsistent analysis, and the lack of data in low- and middle-income countries, highlighting the need for future research.