Serosurveillance is an important epidemiologic tool for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), used to estimate infection rates and the degree of population immunity. There is no general agreement on which antibody biomarker(s) should be used, especially with the rollout of vaccines globally. Here, we used random forest models to demonstrate that a single spike or receptor-binding domain (RBD) antibody was adequate for classifying prior infection, while a combination of two antibody biomarkers performed better than any single marker for estimating time-since-infection. Nucleocapsid antibodies performed worse than spike or RBD antibodies for classification, but can be useful for estimating time-since-infection, and in distinguishing infection-induced from vaccine-induced responses. Our analysis has the potential to inform the design of serosurveys for SARS-CoV-2, including decisions regarding a number of antibody biomarkers measured.

The sporicidal activity of two solutions which have been used in the production of ‘sterile’ pre-injection swabs has been investigated. Propylene oxide (3·4 % w/w) and chlorhexidine diacetate (0·6% w/w), both made up in approximately 65% w/w propan-2-ol, were artificially contaminated with spores of Bacillus subtilis var. niger and swabs were impregnated with these; surviving spores were enumerated at various temperatures and times of storage. Chlorhexidine diacetate had no sporicidal activity, whereas the activity of propylene oxide was dependent on temperature. The former should not be considered a sterilant and the latter can only be considered such if a controlled incubation period at an elevated temperature is employed.

1. The physical, climatic and economic conditions in Nairobi township are briefly discussed. The factor which appears to be most closely related with the incidence of plague is rainfall. A growing season producing, mainly by virtue of ample rainfall, large crops of cereals, which for various reasons may be kept in storage for long periods and become easily available to the rat population, is invariably followed by plague.

2. The numbers of Indians and Africans are given together with the incidence of the disease in these two types and the localities where the disease originates and persists.

3. The distribution of rat and flea species is outlined and shows an irregular distribution of the species of Xenopsylla. The rat population during outbreaks shows a higher density than during quiescent periods, but not such as to indicate that numerical strength alone is the main factor causing outbreaks of plague in the Rattus population. Higher flea populations follow high densities in the rat population.

4. Attention is drawn to the area where plague originates and persists and to the mixed flea population of the locality. Pumwani and Pangani with almost pure cheopis colonies do not figure in early outbreaks and in them the disease ceases much earlier, but they suffer heavily during epidemics.

Outbreaks of plague in Nairobi are associated with grain storage areas and negligence and improvidence are important contributory factors.

5. The results of the survey have enabled some advance to be made in understanding the distribution of the two main species of Xenopsylla. All Rattus living in earth burrows have been found infested with Xenopsylla cheopis, and Rattus living in roofs or walls with Xenopsylla brasiliensis. These facts explain why such places as Pumwani with its African population has a cheopis colony and the K.A.R. lines have brasiliensis. In the Indian Bazaar with varied facilities for nesting, there is a mixed population of fleas.

The application of these facts to rural areas explains why brasiliensis is almost the sole ectoparasite of Rattus living in thatched roof habitations, and why field rodents such as Mastomys coucha and Arvicanthis abyssinicus living underground are hosts to Xenopsylla cheopis.

The twenty-four young women and one man treated in an ultra-clean isolation ward should have had a low incidence of staphylococcal infection on grounds of age, sex and clean environment alone. However, they apparently acquired new strains of Staph. aureus at the rate of 4·7/100 patient weeks (3·9 multiple resistant strains/100 patient weeks) from the sixth week after admission onwards.

Environmental factors contributing to infection included introduction of resistant strains by the patients on admission, contact between patients in the unit, and failure to eliminate nasal carriage in staff and patients.

Host susceptibility was increased by malignancy, and by antibiotic and cytotoxic therapy. The nasal carriage rate of Staph. aureus was significantly greater for patients with repeated episodes of leucopenia induced by cytotoxic drugs.

Tuberculosis (TB) remains a global leading cause of death, necessitating an investigation into its unequal distribution. Sun exposure, linked to vitamin D (VD) synthesis, has been proposed as a protective factor. This study aimed to analyse TB rates in Spain over time and space and explore their relationship with sunlight exposure. An ecological study examined the associations between rainfall, sunshine hours, and TB incidence in Spain. Data from the National Epidemiological Surveillance Network (RENAVE in Spanish) and the Spanish Meteorological Agency (AEMET in Spanish) from 2012 to 2020 were utilized. Correlation and spatial regression analyses were conducted. Between 2012 and 2020, 43,419 non-imported TB cases were reported. A geographic pattern (north–south) and distinct seasonality (spring peaks and autumn troughs) were observed. Sunshine hours and rainfall displayed a strong negative correlation. Spatial regression and seasonal models identified a negative correlation between TB incidence and sunshine hours, with a four-month lag. A clear spatiotemporal association between TB incidence and sunshine hours emerged in Spain from 2012 to 2020. VD levels likely mediate this relationship, being influenced by sunlight exposure and TB development. Further research is warranted to elucidate the causal pathway and inform public health strategies for improved TB control.

A study is described of influenza A anti-neuraminidase antibodies in the sera of young people of three different age groups. Each serum was individually absorbed with viruses containing the N2 neuraminidases of 1957, 1968 and 1972. Rabbit antisera prepared against the viruses were similarly absorbed. Results obtained with the animal sera suggested that these neuraminidases were antigenically distinct, but the human sera had a broader range of anti-neuraminidase activity and gave indication of asymmetric antigenic relationships. Earlier workers who surveyed anti-haemagglutinin antibodies reported that the virus of primary infection absorbed all antibodies, and the virus of secondary infection only those directed against itself. We too found that the virus of secondary infection absorbed only homologous anti-neuraminidase antibody. However, although the primary infecting virus did absorb some secondary antibody, this absorption was incomplete and it lessened with the lengthening of the time interval between the primary and secondary infecting viruses. A similar pattern was seen with anti-haemagglutinin antibodies.

Absorption of anti-neuraminidase antibodies from human sera proved much more difficult than absorption of anti-haemagglutinin antibodies particularly after repeated influenza virus infections. The relative rarity of antigenic shift in the neuraminidase subunit also creates problems in the interpretation of results of serum neuraminidase antibody surveys.

No previous studies have examined Mycobacterium avium complex pulmonary disease (MAC-PD) in only elderly patients ⩾75 years old. Here, we investigated the exacerbating factors of MAC-PD in elderly patients and clarified cases that can be followed up without MAC medication. From April 2011 to March 2019, 126 advanced aged patients at our institute were newly diagnosed with MAC-PD, and could be observed based on radiological findings for over a year. Their medical records were retrospectively examined for clinical and radiological findings at the time of diagnosis and 1 year later. To identify the predictors of exacerbation, clinical characteristics of 109 treatment-naïve patients were compared between exacerbated and unchanged groups. Additionally, the unchanged group was followed for one more year. In the current study, positive acid-fast bacilli smears from the sputum test, the presence of cavitary lesions and extensive radiological findings, particularly abnormal shadows in ⩾3 lobes, were predictive of exacerbation among treatment-naïve elderly MAC-PD patients. In the unchanged group, <10% showed exacerbation of radiological findings within the subsequent year. In conclusion, if the sputum smear is negative, no cavitary lesions are present, and abnormal shadows are restricted to ⩽2 lobes, elderly patients with MAC-PD may remain untreated for a few years.

A clinical trial to determine the effect of oral Humatin therapy on the course of the chronic enteric carrier state in a group of twenty-seven typhoid and paratyphoid B carriers is described. It is concluded that the drug when administered orally in this group of carriers fails in the dosage given to effect a cure of the carrier state.

In this short report, we describe an outbreak of COVID-19 caused by Omicron subvariant BA.5.2.1 in highly vaccinated patients in a respiratory ward in a large acute general hospital in North West London, United Kingdom. The attack rate was high (14/33 (42%)) but the clinical impact was relatively non-severe including in patients who were at high risk of severe COVID-19. Twelve of fourteen patients had COVID-19 vaccinations. There was only one death due to COVID-19 pneumonitis. The findings of this outbreak investigation suggest that while the transmissibility of Omicron BA.5.2.1 subvariant is high, infections caused by this strain are non-severe in vaccinated patients, even if they are at high risk of severe COVID-19 infection.

The skins of grains, all flours and all bread contain bacteria belonging to the group B. mesentericus. The cultural characters of six types of B. mesenteriucus isolated from grains and flour are given. Five of these were also obtained from ropy (or sour) bread. None of these five types can be identified as corresponding to the organisms isolated by earlier workers on rope. Rope, or sourness, does not result from the presence of these bacteria unless conditions are such as to allow of great development. The factors determining development of rope in bread are (1) degree of infection, (2) moisture, (3) temperature, ? (4) reaction, and (5) composition of the flour. A method of estimating the degree of infection of flours is given.

In order to clarify the failure to isolate Shigella spp. by direct plating, we compared frequencies of Shigella spp. isolation by direct plating and by plating after enrichment in selenite broth. A total 67 strains were isolated in this study. The strains of 38 (56·7%) were isolated only by direct plating, and 25 (37·3%) strains were isolated by both direct plating and after enrichment. Four strains (6·0%) were isolated after enrichment but not by direct plating. Since 6% of isolated Shigella spp. were not isolated by direct plating, we recommend that direct plating and additional isolations from selenite broth should be performed. The significance concerning reduction of concentration of sodium selenite in enrichment broth is discussed.

Antistreptolysin O titres in the sera of children in a rural population of Ceylon were determined, to establish the upper limit of the normal ASO titres in nonrheumatic children, and to compare these ASO titres with results of surveys done in other countries.

Swabs were taken from throats and ulcers of the children examined and cultured specifically for group A haemolytic streptoccoci. Of a total of 257 children, 29·5 % had ASO titres of over 166 Todd units. The greatest number of children showed ASO values between 100 and 166 units. The percentage of children showing values over 166 units increased with age until a maximum of 54 % was reached between 9 and 10 years. Group A haemolytic streptococci were isolated from five throat swabs, but there were no isolations from ulcers. The values obtained from this survey have been compared with those from a few other developing countries.

The COVID-19 epidemic showed inter-regional differences in Italy. We used an ecological study design and publicly available data to compare the basic reproduction number (R0), the doubling time of the infection (DT) and the COVID-19 cumulative incidence (CI), death rate, case fatality rate (CFR) and time lag to slow down up to a 50-days doubling time in the first and the second 2020 epidemic waves (δDT50) by region. We also explored socio-economic, environmental and lifestyle variables with multiple regression analysis. COVID-19 CI and CFR changed in opposite directions in the second vs. the first wave: the CI increased sixfold with no evidence of a relationship with the testing rate; the CFR decreased in the regions where it was initially higher but increased where it was lower. The R0 did not change; the initially mildly affected regions, but not those where the first wave had most severely hit, showed a greater δDT50 amplitude. Vehicular traffic, average temperature, population density, average income, education and household size showed a correlation with COVID-19 outcomes. The deadly experience in the first epidemic wave and the varying preparedness of the local health systems might have contributed to the inter-regional differences in the second COVID-19 epidemic wave.

Typhoid fever is one of the prevailing endemic diseases of Palestine. In 1925 and 1926 epidemic outbreaks of considerable magnitude occurred in various parts of the country (Kligler, 1927). As a part of a general programme of the study of the epidemiology of this disease, we have attempted to ascertain the incidence of typhoid carriers in a general population group. Owing to the large number of typhoid cases which occurred there in 1925 and 1926, Afule, a village of some 1200 inhabitants, was chosen as a desirable spot for such an investigation.

Nosocomial outbreak of varicella zoster virus (VZV) has been reported when susceptible individuals encounter a case of chicken pox or shingles. A suspected VZV outbreak was investigated in a 50-bedded in-patient facility of Physical Medicine and Rehabilitation in a tertiary care multispecialty hospital. A 30-year-old female patient admitted with Pott’s spine was clinically diagnosed with chicken pox on 31 December 2022. The following week, four more cases were identified in the same ward. All cases were diagnosed as laboratory-confirmed varicella zoster infection by PCR. Primary case was a housekeeping staff who was clinically diagnosed with chicken pox 3 weeks prior (9 December 2022). He returned to work on eighth day of infection (17 December 2022) after apparent clinical recovery but before the lesions had crusted over. Thirty-one HCWs were identified as contacts a and three had no evidence of immunity. Two of these susceptible HCWs had onset of chickenpox shortly after first dose of VZV vaccination was inoculated. All cases recovered after treatment with no reported complications. VZV infection is highly contagious in healthcare settings with susceptible populations. Prompt identification of cases and implementation of infection prevention and control measures like patient isolation and vaccination are essential for the containment of outbreaks.

A series of spontaneous epidemics of a paratyphoid infection among guinea-pigs is described. It is shown that an epidemic may result from the introduction of a fresh susceptible population into an infected area and vice versa. Such epidemics developed only when the new population was exposed during certain months. The bringing in of a fresh population at the end of November was not followed at the time by an epidemic outbreak; the epidemic did not occur until the following July.

The observed seasonal occurrence was not due to a change in virulence. The strains isolated at the end of the 1926 epidemic did not differ in virulence from those cultivated at the height of the 1927 epidemic.

The guinea-pig may remain a carrier for a long time whilst eliminating bacteria in the faecal discharges only intermittently and in small numbers. In general, even in the case of infected animals, the discharge of pathogenic bacteria is relatively small, except a few days before death.

Attention is called to the parallelism between the seasonal prevalence of human typhoid epidemics in this country and the epidemics of paratyphoid observed in our guinea-pig stock.

It is pointed out that a sound theory of the epidemiology of certain diseases must take into account the seasonal variation in host susceptibility.

Vaccination has reduced the disease burden of vaccine-preventable diseases. However, the extent to which seasonal cycles of immunity could influence vaccine-induced immunity is not well understood. A national cross-sectional serosurveillance study performed in the Netherlands (Pienter-2) yielded data to investigate whether season of vaccination was associated with antibody responses induced by DT-IPV (diphtheria, tetanus and poliomyelitis), MMR (measles, mumps and rubella) and meningococcus C (MenC) vaccines in children. In total, 434 children met the inclusion criteria to study DT-IPV immunity, 811 for MMR and 311 for MenC. Differences in log(antibody levels) by season of vaccination were investigated with linear multivariable regression analyses. Seroconversion rates varied according to season of vaccination for rubella (90% of autumn-vaccinated children vs. 99% of winter-vaccinated had concentrations above cut-off levels). Summer-vaccinated boys showed a slower decline of tetanus antibodies (6% per month), in comparison with winter-vaccinated boys. In conclusion, season of vaccination showed little association with immunological protection. However, a number of associations were seen with a P-value of about 0.03; and adding data from a just-completed nationwide serological study might add more power to the current study. Further immunological and longitudinal investigations could help understand the mechanisms of seasonal influence in vaccine-induced responses.