A total of 100 serum samples including 22 acute phase sera and 39 paired sera collected from clinically diagnosed cases of leptospirosis in Ming-shan County, Sichuan Province, China were examined by the one-point microcapsule agglutination test (MCAT), which was developed in Japan, and by conventional microscopic agglutination tests (MAT). The one-point MCAT is more reactive to IgM antibody than MAT and is superior in detecting antibodies in the early stages of the disease.

The possibility that a devastating human pandemic could arise, causing massive loss of human life, is discussed. Such a major threat to the human species is likely to be a virus, and would spread by the respiratory route. It need not necessarily cause massive loss of life, but if it caused serious illness or incapacity it would still have a major impact. A possible source is from an existing respiratory pathogen, but it would more probably arise from an infection that is maintained in an arthropod or vertebrate host, but which at present either does not infect humans, or if it does it fails to be effectively transmitted between them. More research should therefore focus on the pathogenetic factors and the viral determinants that promote respiratory transmission.

The worldwide increase of resistant S. pneumoniae is a growing clinical problem. In several countries, a more restrictive use of penicillin has been promoted in hope of slowing the rates of resistant pneumococci. However, the consequences of such an action on pneumococcal population dynamics are not fully understood. Thus, a network model was constructed to assess the impacts of penicillin consumption and between-strain competition on the spread of penicillin non-susceptible pneumococci. Model simulations suggest that the age distribution for carriage of penicillin non-susceptible pneumococci, in contrast to susceptible pneumococci, is affected by penicillin consumption. Furthermore, it appears extremely difficult to reduce the incidence of penicillin non-susceptible pneumococci by simply controlling penicillin consumption, assuming that reduced penicillin susceptibility does not confer a fitness cost for the organism. A more judicious use of penicillin together with control measures are in that case required to manage penicillin resistance in pneumococci.

The abrupt transition to heightened poliomyelitis epidemicity in England and Wales, 1947–1957, was associated with a profound change in the spatial dynamics of the disease. Drawing on the complete record of poliomyelitis notifications in England and Wales, we use a robust method of spatial epidemiological analysis (swash-backwash model) to evaluate the geographical rate of disease propagation in successive poliomyelitis seasons, 1940–1964. Comparisons with earlier and later time periods show that the period of heightened poliomyelitis epidemicity corresponded with a sudden and pronounced increase in the spatial rate of disease propagation. This change was observed for both urban and rural areas and points to an abrupt enhancement in the propensity for the geographical spread of polioviruses. Competing theories of the epidemic emergence of poliomyelitis in England and Wales should be assessed in the light of this evidence.

Typical enteropathogenic Escherichia coli (tEPEC) infection is a major cause of diarrhoea and contributor to mortality in children <5 years old in developing countries. Data were analysed from the Global Enteric Multicenter Study examining children <5 years old seeking care for moderate-to-severe diarrhoea (MSD) in Kenya. Stool specimens were tested for enteric pathogens, including by multiplex polymerase chain reaction for gene targets of tEPEC. Demographic, clinical and anthropometric data were collected at enrolment and ~60-days later; multivariable logistic regressions were constructed. Of 1778 MSD cases enrolled from 2008 to 2012, 135 (7.6%) children tested positive for tEPEC. In a case-to-case comparison among MSD cases, tEPEC was independently associated with presentation at enrolment with a loss of skin turgor (adjusted odds ratio (aOR) 2.08, 95% confidence interval (CI) 1.37–3.17), and convulsions (aOR 2.83, 95% CI 1.12–7.14). At follow-up, infants with tEPEC compared to those without were associated with being underweight (OR 2.2, 95% CI 1.3–3.6) and wasted (OR 2.5, 95% CI 1.3–4.6). Among MSD cases, tEPEC was associated with mortality (aOR 2.85, 95% CI 1.47–5.55). This study suggests that tEPEC contributes to morbidity and mortality in children. Interventions aimed at defining and reducing the burden of tEPEC and its sequelae should be urgently investigated, prioritised and implemented.

Sustaining the impact of hepatitis B virus (HBV) vaccination on incidence and prevalence of HBV infection requires increasing and maintaining the uptake of vaccine among those at risk. In recent years, the level of vaccine uptake among people who inject drugs (PWID) in the UK has levelled-off. Data (2015–2016) from the national unlinked-anonymous monitoring survey of PWID, an annual survey that collects data from PWID across England, Wales and Northern Ireland, were used to examine HBV vaccine uptake. Data from participants who had injected drugs during the previous year were used to investigate sources of hepatitis B vaccine doses as well as factors associated with vaccine uptake. Among the 3175 anti-HBc-negative participants, 3138 (99%) reported their vaccination status; 23% (714) reported no vaccine uptake. Among those not vaccinated, 447 (63%) reported being sexually active and 116 (16%) reported sharing needles and syringes. Majority of those not vaccinated reported accessing services in the previous year that could have provided hepatitis B vaccine doses. These missed opportunities for vaccinating of PWID indicate a need for additional targeted interventions.

Five media—MacConkey broth, lactose broth, Teepol broth, lauryl sulphate broth and glucose glutamic acid medium—have been compared as primary media for the isolation of coliform organisms from 1691 samples of water received for examination during a period of 18 months.

Of these samples 1043 (61·7%) gave an identical result in all five media. In the other 648 (38·3%) samples there were differences either in the types of coliform organism isolated or in the rapidity with which the reactions appeared in the different media. The differences in the final yields of coliform organisms and Escherichia coli in the five media are not statistically significant.

There were differences in the number of false presumptive positive reactions given by the different media—lactose broth giving many more false presumptive positive reactions than any of the other media and nearly six times as many as MacConkey broth, which gave the smallest number.

All the reactions tended to appear rather more slowly in glucose glutamic acid medium than in the other media.

Glucose glutamic acid medium has the advantages of being a chemically defined medium and of not containing any substances which are likely to be inhibitory to coliform organisms. Other glutamic acid media may be found on further investigation to give better results than the present glucose glutamic acid medium, but those presented here suggest that media containing glutamic acid are worthy of further investigation.

I am indebted to Dr Ian Sutherland of the M.R.C. Statistical Research Unit for statistical advice and to Dr R. D. Gray of the Public Health Laboratory, Newport (Mon.) and to Dr A. H. Tomlinson of the Public Health Laboratory, Oxford, for much helpful criticism.

A synthetic oligodeoxynucletide of 40 nucleotides corresponding to nucleotides 33–72 of the gene coding for the viral protein VP7 of rotavirus, was used as a nucleic acid probe to develop a non-radiactive hybridization method for rotavirus detection. The probe was labelled at the 3' end with biotin-7-dATP. The sensitivity and specificity of the dot blot hybridization assay for rotavirus detection was evaluated with 303 stool specimens. The results indicate that the hybridization assay has a higher sensitivity than both PAGE and EIA. Among the rotavirus strains tested 37 different electropherotypes were found. The results suggest that rotavirus diagnosis by dot hybridization using a non-radioactive probe may become routine laboratory procedure because it is simple, highly specific and very sensitive.

A dairy herd (77 cows) from Rio de Janeiro, Brazil, with a history of tuberculosis infection was tested by a comparative cervical test (CCT). Seventeen cows were reactive and seven were inconclusive (swelling ⩾2·0 mm and ⩽3·9 mm, respectively). All of these 24 cows were slaughtered and necropsied; samples from lungs and lymph nodes were collected for multiplex polymerase chain reaction (PCR) and culturing. Infection was confirmed in 23/24 (95·8%) of the slaughtered animals (five by culturing, four by PCR, and 14 by both tests). All cows with inconclusive results at CCT were confirmed as infected. Although slaughter of inconclusive reactor cows is not mandatory in many countries, our study provided evidence to support the slaughter of these cows, at least during an outbreak.

Data on the dynamics of malaria incidence, admissions and mortality and their best possible description are very important to better forecast and assess the implementation of programmes to register, monitor (e.g. by remote sensing) and control the disease, especially in endemic zones. Semi-annual and seasonal cycles in malaria rates have been observed in various countries and close similarity with cycles in the natural environment (temperature, heliogeophysical activity, etc.), host immunity and/or virulence of the parasite suggested. This study aimed at confirming previous results on malaria cyclicity by exploring whether trans-year and/or multiannual cycles might exist. The exploration of underlying chronomes (time structures) was done with raw data (without smoothing) by linear and nonlinear parametric regression models, autocorrelation, spectral (Fourier) and periodogram regression analysis. The strongest cyclical patterns of detrended malaria admissions were (i) annual period of 1·0 year (12 months or seasonality); (ii) quasi-biennial cycle of about 2·25 years; and (iii) infrannual, circadecennial cycle of about 10·3 years. The seasonal maximum occurred in May with the minimum in September. Notably, these cycles corresponded to similar cyclic components of heliogeophysical activity such as sunspot seasonality and solar activity cyclicities and well-known climate/weather oscillations. Further analyses are thus warranted to investigate such similarities. In conclusion, multicomponent cyclical dynamics of cerebral malaria admissions in Papua New Guinea were observed thus allowing more specific analyses and modelling as well as correlations with environmental factors of similar cyclicity to be explored. Such further results might also contribute to and provide more precise estimates for the forecasting and prevention, as well as the better understanding, of the dynamics and aetiology of this vector-borne disease.

Typhoid fever is a major cause of illness and mortality in low- and middle-income settings. We investigated the association of typhoid fever and rainfall in Blantyre, Malawi, where multi-drug-resistant typhoid has been transmitting since 2011. Peak rainfall preceded the peak in typhoid fever by approximately 15 weeks [95% confidence interval (CI) 13.3, 17.7], indicating no direct biological link. A quasi-Poisson generalised linear modelling framework was used to explore the relationship between rainfall and typhoid incidence at biologically plausible lags of 1–4 weeks. We found a protective effect of rainfall anomalies on typhoid fever, at a two-week lag (P = 0.006), where a 10 mm lower-than-expected rainfall anomaly was associated with up to a 16% reduction in cases (95% CI 7.6, 26.5). Extreme flooding events may cleanse the environment of S. Typhi, while unusually low rainfall may reduce exposure from sewage overflow. These results add to evidence that rainfall anomalies may play a role in the transmission of enteric pathogens, and can help direct future water and sanitation intervention strategies for the control of typhoid fever.

1. Salmonella paratyphi B possesses a Vi antigen essentially similar to the Vi antigens of Salm. typhi and Salm. paratyphi A.

2. The biological function of the Vi antigen of Salm. paratyphi B is to protect the O antigen against the action of the natural or immune O antibody, thereby increasing the virulence of the microorganism.

3. The most suitable paratyphoid-B vaccine strains are those that develop both the Vi and the O antigens in maximum quantities. The methods of testing vaccine strains of Salm. paratyphi B are essentially the same as those applied to the virulent Vi+O form of Salm. typhi.

4. Evidence is brought to show that Kauffmann's conclusion that Salm. paratyphi B does not develop Vi antigen is unfounded. The so-called O-factors V and V obviously cannot be classified as O antigens.

5. It is suggested that the symbol V of the Kauffmann-White schema be abandoned and this antigenic component be classed as the Vi antigen of Salm. paratyphi B.

The duration of immunity after first severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the extent to which prior immunity prevents reinfection is uncertain and remains an important question within the context of new variants. This is a retrospective population-based matched observational study where we identified the first polymerase chain reaction (PCR) positive of primary SARS-CoV-2 infection case tests between 1 March 2020 and 30 September 2020. Each case was matched by age, sex, upper tier local authority of residence and testing route to one individual testing negative in the same week (controls) by PCR. After a 90-day pre-follow-up period for cases and controls, any subsequent positive tests up to 31 December 2020 and deaths within 28 days of testing positive were identified, this encompassed an essentially vaccine-free period. We used a conditional logistic regression to analyse the results. There were 517 870 individuals in the matched cohort with 2815 reinfection cases and 12 098 first infections. The protective effect of a prior SARS-CoV-2 PCR-positive episode was 78% (odds ratio (OR) 0.22, 0.21–0.23). Protection rose to 82% (OR 0.18, 0.17–0.19) after a sensitivity analysis excluded 933 individuals with a first test between March and May and a subsequent positive test between June and September 2020. Amongst individuals testing positive by PCR during follow-up, reinfection cases had 77% lower odds of symptoms at the second episode (adjusted OR 0.23, 0.20–0.26) and 45% lower odds of dying in the 28 days after reinfection (adjusted OR 0.55, 0.42–0.71). Prior SARS-CoV-2 infection offered protection against reinfection in this population. There was some evidence that reinfections increased with the alpha variant compared to the wild-type SARS-CoV-2 variant highlighting the importance of continued monitoring as new variants emerge.

Unlike most jurisdictions in the United States, Alaska performs pulsed-field gel electrophoresis (PFGE) characterization of all Campylobacter sp. isolates at the state public health laboratory – a practice that started in 2002. Moreover, in order to ensure early detection and response to campylobacteriosis outbreaks, the Alaska Section of Epidemiology has investigated all incident Campylobacter sp. case reports since 2004. This report summarizes the public health impact of routine incident case investigations and molecular characterization of all Campylobacter sp. isolates. In sum, we found that these efforts have contributed to better characterization of the epidemiology of campylobacteriosis in Alaska, and facilitated more rapid outbreak detection, more public health investigations, and earlier public health interventions.

Acute flaccid paralysis (AFP) surveillance data from India were analysed to examine sensitivity of poliovirus isolation from stool specimens and the added sensitivity obtained from collection of a second stool specimen. Analysis was restricted to Indian AFP cases, 1998–2000, with two adequate stool specimens. The proportion of cases confirmed with wild poliovirus isolation by the second specimen only was calculated, regardless of specimen quality. Overall specimen sensitivity (1998–2000) was 81% using the first specimen, 78% using the second, and 96% using both. Sensitivity increased from 1998 to 2000, with slightly higher sensitivity each year for the first specimen. The second specimen increased sensitivity by 15% overall and contributed more when the first specimen was collected late or was in poor condition. As wild poliovirus disappears, increased sensitivity provided by a second stool specimen may reduce the risk of missing circulating virus.

Active protection against Pseudomonas aeruginosa could be induced in mice by immunization with either the phenol killed cells or the alcohol precipitated fraction of the slime layer, or the ribosomal vaccine preparation. Passive protection could also be induced by injecting into mice antisera prepared in rabbits against these bacteria. This protection was due to the production of antibodies in reaction to the slime layer; the absorption of these antibodies by the slime caused the loss of protection. The fact that mice were also protected by vaccination with strains other than those used for challenging was attributed to the presence of an antigenically similar slime. Passive protection towards a heterologous strain, even one with an antigenically similar slime layer, was dependent on the dose of the challenging injection.

We assessed severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) reverse transcriptase-polymerase chain reaction (RT-PCR) diagnostic sensitivity and cycle threshold (Ct) values relative to symptom onset in symptomatic coronavirus disease-2019 (COVID-19) patients from Bavaria, Germany, of whom a subset was repeatedly tested. Locally weighted scatterplot smoothing method was used to assess the relationship between symptom onset and Ct-values. Kaplan−Meier plots were used to visualise the empirical probability of detecting viral ribonucleic acid (RNA) over time and estimate the time until clearance of viral RNA among the repeatedly tested patients. Among 721 reported COVID-19 cases, the viral RNA was detected in specimens taken between three days before and up to 48 days after symptom onset. The mean Ct-value was 28.6 (95% confidence interval (CI) 28.2–29.0) with the lowest mean Ct-value (26.2) observed two days after symptom onset. Up to 7 days after symptom onset, the diagnostic sensitivity of the RT-PCR among repeatedly sampled patients (n = 208) remained above 90% and decreased to 50% at day 12 (95% CI 10.5–21.5). Our data provide valuable estimates to optimise the timing of sampling of individuals for SARS-CoV-2 detection. A considerable proportion of specimens sampled before symptom onset had Ct-values comparable with Ct-values after symptom onset, suggesting the probability of presymptomatic transmission.

The foregoing report of Professor van Loghem and his co-worker, Miss Benjamins, confirms the results found by Professor Beattie and Dr Lewis, concerning the bactericidal action in milk of the electric current of high voltage. It also proves that the sterilising power of electrical treatment with carbon electrodes is not inferior to that with copper electrodes. These results, and also my experience of the vitamin C sparing effect of the carbon electrodes, have caused me to recommend the use of this kind of electrode in the electric treatment of milk, provided that the milk used be fresh and that it contains but little oxygen. The same reservation applies to milk pasteurised by heat and to pure raw certified milk. It is important that the supply should be fresh.

We collected monthly reports on gastrointestinal illness (GII) episodes among 2348 adults in a 1-year cohort in South West Sweden. The GII episodes were collected by SMS (Short Message System) and validated by telephone interviews among the cohort participants and nationwide. The annual incidence was 0.64 and 0.43 cases per person-year for 28-day self-defined GII (any symptom) and acute GII (vomiting and/or ≥3 episodes of diarrhoea), respectively. The incidence was about 20% higher for the 14-day recall, compared with 28-day recall. The duration of illness was on average 2.3 days. We observed a unimodal seasonal distribution of GII, with the highest prevalence during winter. Responses collected by SMS highly correlated with responses collected by telephone. SMS survey was an efficient tool for the collection of repeated estimates of GII.