1. The trypanosome of the gold-fish has been successfully cultivated on the medium of McNeal and Novy.

2. Preparatory to division in culture, the original trypanosome as found in the blood of the fish assumes a somewhat tadpole-like appearance, the endoplasm and its contained structures being collected together in the swollen posterior end. The kineto-nucleus now lies close to, and alongside of, the tropho-uncleus, and the latter has become swollen and loose in structure with its chromatin broken up into chromidia. The anterior third or more of the trypano-some undergoes little or no change in form and does not take part in division. It is thus easily seen how the product of the preliminary division comes to have a Crithidia-like appearance.

3. The product of this preliminary division—Crithidia-like by the relative position of kineto-and tropho-nuclei—is capable of freely multiplying.

According to Brumpt it is in the Crithidia-like form that free multiplication of the eel trypanosome first takes place in the stomach of Hemiclepsis. It may well be that in this case also the Crithidia-like form is arrived at by steps such as are here figured and described.

4. Crithidia-like forms are found at all stages of the culture and along with them at various stages other forms where the body is elongated and the kineto-nucleus still close to the tropho-nucleus, and yet other forms where the kineto-nucleus until true trypanosome-like forms are reached.

5. These trypanosome-like forms (resembling mammalian trypanosomes rather than those of the fish from which they are derived) are most numerous in the later stages of the culture.

1. V strains of Bact. typhosum can be sterilized by means of merthiolate or colloidal silver without destructive effect on either the Vi or O antigens.

2. Suspensions in physiological saline sterilized and preserved by the addition of either merthiolate or silver retain their property of stimulating Vi antibody formation in the rabbit for at least one year if stored at 0–2° C, but when stored at 23–25° C. this property is lost after 4 months' storage.

3. The Vi antibody-stimulating property of a merthiolate-killed and preserved suspension in physiological saline is almost completely destroyed by an exposure of 5 days at 37° C. or 4 hr. at 60° C.

4. Bact. typhosum bacilli killed with merthiolate or alcohol, and dried with acetone, show no loss of Vi antigen when stored in the dry state for 1 year at 23–25° C, or after 3 months at 37° C.

5. Suspensions sterilized and preserved with merthiolate in 32% saline will withstand 50 days' storage at 37° C, or 7 months at 23–25° C, without significant loss of their Vi antibody-stimulating properties.

6. Suspensions in 32% saline can be sterilized by an exposure to 60° C. for 2 hr., and even after 4 hr. exposure at this temperature, show no loss of Vi antigen content.

7. Suspensions killed by merthiolate or alcohol, and preserved by the addition of 25% alcohol in physiological saline, failed to stimulate Vi antibody formation in the rabbit after being stored for 20 days at 37° C.

8. The application of these findings to the production of a stable T.A.B.C. vaccine of enhanced immunological qualities is discussed.

9. The effect of mixing Bact. typhosum with tetanus formol-toxoid has been examined, and the advisability of employing heat-killed-phenolized vaccine mixed with tetanus formol-toxoid for combined immunization against tetanus and typhoid infections is discussed.

10. A suggested technique for the preparation, supply, and administration of two new types of T.A.B.C. vaccine is described.

In a large institution whose population can be considered as forming a semiclosed community there frequently exist conditions favourable to the spread of infectious diseases. The organization of such an institution to avoid epidemics is an accepted difficulty of administration. The occurrence of an epidemic in a semi-closed community offers opportunity for thorough investigation, and is, therefore, of more than usual interest.

In India, rotavirus infections cause the death of 98621 children each year. In urban neighbourhoods in Delhi, children were followed up for 1 year to estimate the incidence of rotavirus gastroenteritis and common genotypes. Infants aged ⩽1 week were enrolled in cohort 1 and infants aged 12 months (up to +14 days) in cohort 2. Fourteen percent (30/210) gastroenteritis episodes were positive for rotavirus. Incidence rates of rotavirus gastroenteritis episodes in the first and second year were 0·18 [95% confidence interval (CI) 0·10–0·27] and 0·14 (95% CI 0·07–0·21) episodes/child-year, respectively. The incidence rate of severe rotavirus gastroenteritis in the first year of life was 0·05 (95% CI 0·01–0·10) episodes/child-year. There were no cases in the second year. The common genotypes detected were G1P[8] (27%) and G9P[4] (23%). That severe rotavirus gastroenteritis is common in the first year of life is relevant for planning efficacy trials.

Sixteen strains of Salmonella typhimurium phage type 179 were referred to the National Health Institute, Wellington, New Zealand, from 1977 to 1979. This phage type had not been observed here before 1977. All strains were resistant to ampicillin, several were also resistant to tetracycline, and several were resistant to ampicillin, tetracycline, sulphafurazele and trimethoprim. All resistances could be transferred to Escherichia coli K 12. Plasmids from these strains and their transconjugants were characterized by agarose gel electrophoresis. It appears that resistance to sulphafurazole and trimethoprim is carried on a plasmid with a molecular weight of 5·2 Mdal and that resistance to ampicillin and tetracycline is carried on a plasmid with a molecular weight of approximately 60 Mdal.

Diarrhoeal management practices are unsatisfactory in India especially in the slum areas. Dearth of information regarding physicians' diarrhoea-related knowledge and practice in India ncessitated this cross-sectional study of allopathic practitioners in the slums of Kolkata, to assess the distribution and interrelationship between physicians' characteristics, knowledge and practice regarding diarrhoea. A total of 264 randomly selected consenting practitioners were interviewed using a field-tested questionnaire. Nineteen percent had good overall knowledge, 49% and 80% prescribed antibiotics to diarrhoea and cholera patients, respectively, and 55% advised stool examination for every case. Qualified and Government physicians had better knowledge regarding diarrhoea [MBBS: odds ratio (OR) 5·96, P < 0·001; postgraduates: OR 9·33, P < 0·001; Government physicians: OR 11·49, P < 0·0001] and were less likely to prescribe antibiotics for all diarrhoea cases (MBBS: OR 0·30, P = 0·002; postgraduates: OR 0·20, P < 0·001; Government physicians OR 0·24, P < 0·029). Better knowledge was associated with a lower likelihood of prescribing antibiotics for diarrhoea (OR 0·72, P < 0·001), cholera (OR 0·78, P = 0·027) and investigative procedure (OR 0·85, P = 0·028). In the slums of Kolkata, diarrhoea-related knowledge and practice were poor with the exception of qualified physicians, hence an improvement in the knowledge of pharmacists and unqualified practitioners is necessary for the overall improvement of diarrhoeal management in these slums.

Invasive meningococcal disease (IMD) is thought to occur within a few days of pharyngeal acquisition of Neisseria meningitidis. During a longitudinal study of carriage and acquisition among 2453 first-year undergraduates we identified a male student from whom N. lactamica was isolated in October 1997 followed by N. meningitidis in December 1997. In mid-January 1998 this student suffered a mild episode of IMD (meningitis) during which N. meningitidis was isolated from his CSF. The meningococcus carried in December 1997 was phenotypically and genotypically indistinguishable from the invading organism, suggesting the possibility that the organism may have been carried for 7 weeks prior to the onset of invasive disease. Further studies are needed to assess more accurately the range of asymptomatic carriage prior to disease onset.

In vivo methods were used to study the F38-type mycoplasma in parallel with related mycoplasmas.

Three of five strains of ‘bovine serogroup 7’ with an unknown history of subculture produced mycoplasmaemia in mice inoculated intraperitoneally. A strain of ‘bovine serogroup L’ also produced mycoplasmaemia, but no evidence of similar ability could be found for single strains of Mycoplasma capricolum, M. equigenitalium and M. primatum, or for two strains of the F38-type mycoplasma.

In cross-immunization tests a bovine serogroup 7 strain (NCTC 10133) and a strain (‘Blenheim’) of the SC (small colony) type of M. mycoides subsp. mycoides were used for the purpose of challenge. Cross-protection was described as ‘complete’ or ‘partial’, depending on whether it was as great as, or less than, that produced by homologous vaccine. Although strain NCTC 10133 protected strongly, possibly completely, against Blenheim, and Blenheim gave partial protection against NCTC 10133, challenge with NCTC 10133 and Blenheim gave strikingly different results. Thus (1) F38-type strains, M equigenitalium and M. primatum all gave partial cross-protection against NCTC 10133 but not against Blenheim, (2) NCTC 10133, unlike Blenheim, was seldom susceptible to partial cross-protection by LC (large colony) strains of M. mycoides subsp. mycoides, and (3) three SC strains – which would have protected completely against Blenheim – protected only partially against NCTC 10133. NCTC 10133 and Blenheim were similar, however, in that M. capricolum and M. mycoides subsp. capri failed to cross-protect against them both.

Puumala virus (PUUV) is the causative agent of nephropathia epidemica, a mild form of haemorrhagic fever with renal syndrome. PUUV is transmitted to humans via aerosolized excreta of the infected bank vole (Clethrionomys glareolus). Current methods for screening of the PUUV prevalence among bank vole populations are laborious, combining sampling in the field and subsequent analyses in the laboratory. In order to facilitate animal testing, a new serological immunochromatographic rapid test was developed. The test uses PUUV nucleocapsid protein as antigen, and it detects anti-PUUV IgG antibodies in rodents. With fresh and undiluted bank-vole blood samples (n=105) the efficacy of the test was 100%, and with frozen and diluted samples (n=78) the efficacy was 91%. The test was also shown to detect related hantavirus infections in Norway lemmings and sibling voles (n=31) with 99% efficacy. The test provides an applicable tool for studying PUUV and related hantavirus infections in arvicoline rodents.

The objective of this study was to model the age–time-dependent incidence of hepatitis B while estimating the impact of vaccination. While stochastic models/time-series have been used before to model hepatitis B cases in the absence of knowledge on the number of susceptibles, this paper proposed using a method that fits into the generalized additive model framework. Generalized additive models with penalized regression splines are used to exploit the underlying continuity of both age and time in a flexible non-parametric way. Based on a unique case notification dataset, we have shown that the implemented immunization programme in Bulgaria resulted in a significant decrease in incidence for infants in their first year of life with 82% (79–84%). Moreover, we have shown that conditional on an assumed baseline susceptibility percentage, a smooth force-of-infection profile can be obtained from which two local maxima were observed at ages 9 and 24 years.

A method of titrating influenza virus-neutralizing antibodies is described. This method is based on the technique for cultivating virus in fragments of chick chorio-allantoic membrane using a special plastic tray with cups for 100 replicates. The neutralization test cannot be made directly by adding the antiserum to the cups in which the virus is growing in the membrane fragments because there is a significant non-specific inhibitory effect. Therefore, use is made of the observation that virus added to the cups is rapidly fixed by the membrane so that, after a short time, the membrane may be washed and transferred to a fresh cup which will later be found to contain the new virus released from the membrane.

In the neutralization test the membrane fragments are exposed to virus-serum mixtures for 18 hr. and then transferred to other cups without serum to determine which pieces have become infected. The titre of neutralizing antibodies is defined as the serum dilution which will protect from infection with 100 ID 50 of virus, half of a large number of replicate pieces of membrane.

The neutralization technique has been applied to the antigenic comparison of six strains of influenza virus. The results support the relationships disclosed between the six strains by a complement-fixation technique. It is suggested, however, that the neutralization technique, because of its greater specificity, and because of its dependence on the infectivity of the strain, is not as satisfactory as the complement-fixation test for strain comparisons. Apart from its use for titrating neutralizing antibodies, the technique may also be of value for proving the virtual identity of two virus strains and in the selection of strains for a vaccine.

It is a pleasure to acknowledge the help given by Dr Isaacs of the WHO Influenza Centre. Not only did he provide many of the virus strains and antisera, but he also undertook the purification of the WS strain.

A sentinel surveillance system for the control of sexually transmitted diseases (STD) among foreigners was developed in Italy in 1991. From January 1991 to June 1995, 4030 foreigners with a new STD episode were reported. More than one-third of them were North-Africans. The most frequent STDs were non-specific urethritis and genital warts among men, and non-specific vaginitis and latent syphilis among women. The overall HIV prevalence was 5%, with large differences in rates in people from different continents. Very high HIV-positivity rates were observed among homosexuals and homosexual IDUs from Central–South America, with 39·1% and 77·8% seropositive individuals respectively.

These data stress the need for increased knowledge of both the spread of and risk factors for STDs among immigrants. Particular attention should be paid to counselling procedures focused on the prevention of risk behaviours for acquiring STDs and HIV infection.

On 13 June 2013, a fever and diarrhoea outbreak occurred in a boarding school in Sichuan Province. We conducted a field investigation and compared food exposure of 81 case students and 104 control students (years 7 and 8) in order to identify the source of infection. There were 401 cases identified (399 students and two cooks). The attack rates were 23–46% in nursery, primary, and secondary schools, but 0% in the high school. Eighty-five percent of case students, consumed cowpea salad compared to 60% of control students at lunch on 12 June (odds ratio 3·1, 95% confidence interval 1·3–7·8). The cowpeas were stored at room temperature for 3 h in a bucket previously used to store raw ingredients. The bucket was cleaned using water without a disinfectant. There were two buckets of cowpea, one for the high-school students and another for the other students. This Salmonella outbreak was likely caused by the cowpea salad due to cross-contamination via a storage bucket.

The sources of airborne bacteria within living quarters are minute droplet nuclei which remain suspended in the air following expulsion from a carrier and contaminated particles which have become suspended from dried environmental deposits. Since group A streptococci may be isolated from environmental deposits in populations experiencing an epidemic of streptococcal respiratory disease (Loosli, Lemon, Wise & Robertson, 1952), it has been assumed that contaminated particles of dust serve as an important reservoir of infection. Indeed, many of our measures employed to control respiratory infection in recent years have been directed against this reservoir.

Any conclusions that are reached in such an enquiry as this can only be put forward very tentatively, for they are based (1) upon limited data which cannot be free entirely from error, and (2) upon the averaging of individual results drawn, it is true, from the same class, but from families varying considerably in economic status. For this reason, without much further investigation, any generalisation would be out of place, and the conclusions summarised below are put forward not as definite results but only as indications of the actual facts.

(1) In view of the fact that minimum wage legislation for agricultural workers is being introduced in answer to the statements that the economic status of these workers is deplorably low, it is important to bring forward any facts relating to the actual condition of the rural families.

(2) For an investigation of these conditions, Essex (rural districts) was chosen as the field of enquiry in 1923, and for purposes of comparison and confirmation of results earlier rural investigations have been utilised.

(3) A study of the experimental work on metabolism suggests that the agricultural labourer would certainly need a gross amount of at least 3300 calories per day, and that this assumption will not be likely to err on the side of excess.

(4) The Essex studies of 1923 give a mean value of 2872 calories per man value per day and only 17 per cent. of the families secure over 3300 calories per man per day.

(5) This result is not at variance with the conclusions reached in earlier investigations in rural areas, and the suggestion accordingly is that underfeeding is, to some extent, present in the rural areas. (Lusk writes “it is evident… that one may reduce the basal requirement of energy by undernutrition, and that this process may largely economise food, but that to accomplish a given amount of work a fixed amount of food-fuel is required, irrespective of the nutritive condition of the organism.”)

(6) This under-feeding occurs although nearly three-quarters of the total income is spent on food (leaving a very small amount for other essentials and practically nothing for non-essentials), and although the diet is substantially increased by the consumption of home produce. Without the latter the diet would be seriously deficient.

(7) In the Essex studies nearly one-third of the money spent on food was devoted to bread and flour.

(8) On the other hand, in comparison with urban studies, the rural diet compares very favourably with that of urban workers possessed of a higher money income.

(9) This advantage to the rural family is gained by (a) a larger percentage expenditure on food; (b) a less varied diet containing a substantially smaller amount of meats and hence less animal protein; a substantially larger amount of breadstuffs and hence more carbohydrates in place of fats1; (c) by the consumption of home produce, which, however, entails, in its turn, a lengthening of the day's work and increased needs for food. Without this home produce the diets would compare very unfavourably with those of the urban workers studied. With it, the Vitamine content, as well as the energy value of the diet, must be substantially increased.

(10) In spite of the diet being low there is little evidence of malnutrition amoung the rural children of Essex, and their physique is better, age for age, than that of urban children, living on a diet equivalent or superior in energy value. Other factors, especially the “racial” factor and the “fresh air and sunlight” factor, however, must exert such an influence that the efficacy of the diets cannot be satisfactorily measured by a comparison of heights and weights.

In connection with recent investigations on the spread of bacterial infection among mice, the possible effect of variations in the virulence of the infecting organism has, inevitably, formed one of the problems for study.

This study aimed to analyse the spatial–temporal distribution of COVID-19 mortality in Sergipe, Northeast, Brazil. It was an ecological study utilising spatiotemporal analysis techniques that included all deaths confirmed by COVID-19 in Sergipe, from 2 April to 14 June 2020. Mortality rates were calculated per 100 000 inhabitants and the temporal trends were analysed using a segmented log-linear model. For spatial analysis, the Kernel estimator was used and the crude mortality rates were smoothed by the empirical Bayesian method. The space–time prospective scan statistics applied the Poisson's probability distribution model. There were 391 COVID-19 registered deaths, with the majority among ⩾60 years old (62%) and males (53%). The most prevalent comorbidities were hypertension (40%), diabetes (31%) and cardiovascular disease (15%). An increasing mortality trend across the state was observed, with a higher increase in the countryside. An active spatiotemporal cluster of mortality comprising the metropolitan area and neighbouring cities was identified. The trend of COVID-19 mortality in Sergipe was increasing and the spatial distribution of deaths was heterogeneous with progression towards the countryside. Therefore, the use of spatial analysis techniques may contribute to surveillance and control of COVID-19 pandemic.

Occurrence of Salmonella spp. in captive wild animal species in India is largely unknown. The purpose of this study was to determine the occurrence of different Salmonella serotypes, antimicrobial resistance patterns and genotypic relatedness of recovered isolates. A total of 370 samples including faecal (n = 314), feed and water (n = 26) and caretakers stool swabs (n = 30) were collected from 40 different wild animal species in captivity, their caretakers, feed and water in four zoological gardens and wildlife enclosures in India. Salmonellae were isolated using conventional culture methods and tested for antimicrobial susceptibility with the Kirby–Bauer disc diffusion method. Salmonella isolates were serotyped and genotyping was performed using enterobacterial repetitive intergenic consensus (ERIC) PCR and 16S rRNA sequencing. Animal faecal samples were also subjected to direct PCR assay. Salmonella was detected in 10 of 314 (3.1%) faecal samples by isolation and 18 of 314 (5.7%) samples by direct PCR assay; one of 26 (3.8%) feed and water samples and five of 30 (16.7%) caretakers stool swabs by isolation. Salmonella was more commonly isolated in faecal samples from golden pheasants (25%; 2/8) and leopard (10%; 2/20). Salmonella enterica serotypes of known public health significance including S. Typhimurium (37.5%; 6/14), S. Kentucky (28.5%; 4/14) and S. Enteritidis (14.3%; 2/14) were identified. While the majority of the Salmonella isolates were pan-susceptible to the commonly used antibiotics. Seven (43.7%; 7/16) of the isolates were resistant to at least one antibiotic and one isolate each among them exhibited penta and tetra multidrug-resistant types. Three S. Kentucky serotype were identified in a same golden pheasants cage, two from the birds and one from the feed. This serotype was also isolated from its caretaker. Similarly, one isolate each of S. Typhimurium were recovered from ostrich and its caretaker. These isolates were found to be clonally related suggesting that wildlife may serve as reservoir for infections to humans and vice versa. These results emphasise the transmission of Salmonella among hosts via environmental contamination of feces to workers, visitors and other wildlife.

From 2016–2019, dry bulb onions were the suspected cause of three multistate outbreaks in the United States. We investigated a large multistate outbreak of Salmonella Newport infections that caused illnesses in both the United States and Canada in 2020. Epidemiologic, laboratory and traceback investigations were conducted to determine the source of the infections, and data were shared among U.S. and Canadian public health officials. We identified 1127 U.S. illnesses from 48 states with illness onset dates ranging from 19 June to 11 September 2020. Sixty-six per cent of ill people reported consuming red onions in the week before illness onset. Thirty-five illness sub-clusters were identified during the investigation and seventy-four per cent of sub-clusters served red onions to customers during the exposure period. Traceback for the source of onions in illness sub-clusters identified a common onion grower in Bakersfield, CA as the source of red onions, and onions were recalled at this time. Although other strains of Salmonella Newport were identified in environmental samples collected at the Bakersfield, CA grower, extensive environmental and product testing did not yield the outbreak strain. This was the third largest U.S. foodborne Salmonella outbreak in the last 30 years. It is the first U.S. multistate outbreak with a confirmed link to dry bulb onions, and it was nearly 10-fold larger than prior outbreaks with a suspected link to onions. This outbreak is notable for its size and scope, as well as the international data sharing that led to implication of red onions as the primary cause of the outbreak. Although an environmental assessment at the grower identified several factors that likely contributed to the outbreak, no main reason was identified. The expedient identification of the outbreak vehicle and response of multiple public health agencies allowed for recall and removal of product from the marketplace, and rapid messaging to both the public and industry on actions to protect consumers; these features contributed to a decrease in cases and expeditious conclusion of the outbreak.

1. A group of rats has been fed on a poor human dietary supplemented with milk and green food. A further group has been given the same dietary supplemented with Ca and P as salts, equivalent in amount to that present in the milk and green food. The experiment has been continued over three generations.

2. The diet supplemented with Ca and P salts has been found to be as effective as that containing milk and green food in promoting reproduction, calcification and tooth formation; it has induced growth as effectively in the first generation of rats but is unable to maintain this growth rate as effectively over several generations. It is obvious that Ca and P are of the chief deficiencies in the poor diet. The addition of these elements greatly increases the nutritive value of this diet, but they are inferior in this respect to milk and green food supplements.

3. Under conditions of Ca and P lack, tooth formation is much less adversely affected than is skeletal ossification.