A total of 32 Vibrio ordalii strains were studied for their plasmid content and shown to carry a plasmid of approximately 32 kb. This plasmid was subsequently subjected to restriction fragment length polymorphism (RFLP) studies. Using Hind III, three different restriction patterns were identified while BamHI cleaved the plasmid into a single linear fragment. The results suggest that the 32 kb plasmid is highly conserved but that some variation in restriction pattern occurs. The same set of strains was subjected to ribotyping. Using Mlu I, six different restriction patterns were demonstrated. Strains from the USA and Canada shared profiles with strains from Australia and Japan. Strains from Australia generated a single pattern whereas strains from North America were subdivided into three patterns, and the Japanese strains fell into five patterns. The results suggest that ribotyping in combination with RFLP studies of the pMJ101-like plasmid may be useful in epidemiological studies of V. ordalii.

Dengue virus circulates as four independent serotypes posing a major public health threat around the globe. In the recent years, frequent dengue outbreaks are being reported in many parts of the world including India. Among four serotypes, Den-4 is the least sampled and studied serotype until recent times, but the reported cases with Den-4 infections were mostly known to associate with severe dengue. In the past three decades, only one complete genome sequence of Den-4 has been published from India. Hence there is a deficit in information with reference to this serotype which would be required in deciphering its association with severe dengue. In this study, we have carried out the complete genome characterization of Den-4 virus, isolated from a dengue shock syndrome patient during the 2015 outbreak from Hyderabad, South India. Phylogenetic analysis revealed the circulation of genotype I (lineage C) which showed close relatedness to the reported virulent strains. The data also indicated few unique amino acid substitutions which are known to be important in virus replication and epitope presentation. This is the first report of complete genome characterization of Den-4 from South India, which may assist in shaping the genetic diversity of circulating strains in India.

As of 03 January 2021, the WHO African region is the least affected by the coronavirus disease-2019 (COVID-19) pandemic, accounting for only 2.4% of cases and deaths reported globally. However, concerns abound about whether the number of cases and deaths reported from the region reflect the true burden of the disease and how the monitoring of the pandemic trajectory can inform response measures.

We retrospectively estimated four key epidemiological parameters (the total number of cases, the number of missed cases, the detection rate and the cumulative incidence) using the COVID-19 prevalence calculator tool developed by Resolve to Save Lives. We used cumulative cases and deaths reported during the period 25 February to 31 December 2020 for each WHO Member State in the region as well as population data to estimate the four parameters of interest. The estimated number of confirmed cases in 42 countries out of 47 of the WHO African region included in this study was 13 947 631 [95% confidence interval (CI): 13 334 620–14 635 502] against 1 889 512 cases reported, representing 13.5% of overall detection rate (range: 4.2% in Chad, 43.9% in Guinea). The cumulative incidence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was estimated at 1.38% (95% CI: 1.31%–1.44%), with South Africa the highest [14.5% (95% CI: 13.9%–15.2%)] and Mauritius [0.1% (95% CI: 0.099%–0.11%)] the lowest. The low detection rate found in most countries of the WHO African region suggests the need to strengthen SARS-CoV-2 testing capacities and adjusting testing strategies.

We studied the epidemiology and microbiology of Clostridium difficile and the characteristics of patients with C. difficile infection (CDI) in Crete in three groups of hospitalized patients with diarrhoea: group 1 [positive culture and positive toxin by enzyme immunoassay (EIA)]; group 2 (positive culture, negative toxin); group 3 (negative culture, negative toxin). Patients in group 1 were designated as those with definitive CDI (20 patients for whom data was available) and matched with cases in group 2 (40 patients) and group 3 (40 patients). C. difficile grew from 6% (263/4379) of stool specimens; 14·4% of these had positive EIA, of which 3% were resistant to metronidazole. Three isolates had decreased vancomycin susceptibility. Patients in groups 1 and 2 received more antibiotics (P = 0·03) and had more infectious episodes (P = 0·03) than patients in group 3 prior to diarrhoea. Antibiotic administration for C. difficile did not differ between groups 1 and 2. Mortality was similar in all three groups (10%, 12·5% and 5%, P = 0·49). CDI frequency was low in the University Hospital of Crete and isolates were susceptible to metronidazole and vancomycin.

A complement-fixation test for acute poliomyelitis using unheated antigens derived from suckling mouse brain infected with poliovirus Type 1 or Type 2 is described.

The results of tests in 62 patients clinically diagnosed as cases of acute poliomyelitis in a recent epidemic and in 26 controls are recorded.

The CF tests were positive in 100% of 53 cases with poliovirus Type 1 and/or Type 2 in stool. A positive result was obtained in 23 (76%) of 30 cases whose sera were examined in the first 7 days of illness.

Negative tests of the initial serum samples were found in 15 (28·5%) of 53 cases, but all these became positive in titres of 40 or 80 on testing of convalescent serum.

In 31 (69%) of 45 cases whose sera were re-tested between the 3rd and 4th weeks of illness the CF antibody levels rose, reaching titres of 80 or 160 in most instances. Of the remaining 14 cases only one dropped in insignificant degree (from titre 320 to 160) and the 13 stationary results had been positive in titres of 40–160 on initial tests most of which were performed in the 2nd week of illness.

Homotypic CF antibody response without crossing was found in 37 (71%) of 52 cases with Type 1 or Type 2 virus in stool. In the cases of crossing the heterotypic antibody response was either transient, diminishing or stationary in all and in only low titre in most instances.

In 26 control cases there were seven positive CF tests, but one of these was nonspecific, five were in lowest titres, and one case appeared to have had recent poliomyelitis infection.

Heating the antigens did not broaden the reaction. It caused only slight loss of potency except in two cases in which the CF titre increased substantially.

The antigenic preparation described appears to be superior to antigens of other origin in the diagnosis of acute poliomyelitis by complement-fixation tests, as positive tests are recognized earlier in the illness and the titres are higher. Homotypic results were obtained in all cases and no instance of false negative occurred in this series.

I would like to thank the medical staff of the Cape Town City Hospital for Infectious Diseases for the trouble taken in collecting stools and paired sera, and Prof. Kipps for his interest in this work. I am indebted to Miss Karin Larssen for valuable technical assistance.

An emerging recombinant norovirus GII.P16/GII.4 Sydney 2012 strain caused a gastroenteritis outbreak amongst attendees at a large health function in regional New South Wales, Australia. This was the third outbreak caused by the recombinant GII.P16/GII.4 Sydney 2012 strain in this region in 2017, which appears to be emerging as a common strain in the Hunter New England region.

The determination of the presence or absence of B. coli in a drinking water is universally regarded as the estimation of most value in determining its safety or as grounds for its condemnation. Valuable as this estimation is it is desirable that, if possible, it should be reinforced and confirmed by the determination of the presence or absence of other organisms. In particular it would be of extreme value and importance if the isolation of other selected organisms could be used to throw light upon two points in regard to which evidence is either lacking or indefinite at the present time. These two matters are the question as to whether ascertained contamination is of human or animal origin and as to the probable date of any contamination shown to be present. The B. coli enumeration does throw considerable light upon the latter, but none upon the former point.

The “Radiation Integrator in Vacuo” is an instrument designed by a biologist, to assist in the study of solar radiation, as received on the surface of the earth. The principle of the instrument is that a black bulb in vacuo is exposed to the sun's rays; the bulb, which contains alcohol, is connected to a graduated stem maintained at shade temperature; radiant heat from the sun causes alcohol to distil over the bulb into the stem where its volume is measured. In Samoa the shade temperature is practically constant throughout the year, but one believes on theoretical grounds that more radiation is received from the sun between September and March than at the other season, and that the radiation has two maxima, in October and February. This instrument, which has been observed for 12 months, confirms the expectation. The daily mean distillate, the distillate per hour of sunshine (Campbell Stokes) and the mean distillate for the three hours before noon, all show the same seasonal changes.

The instrument has been standardized against Gorczynski's pyrheliometer, so that the readings in c.c. of alcohol can be converted into calories. The instrument is not difficult to make or read, and it can be left in the open in all weathers. It integrates its results and requires to be read once a day in Samoa.

We evaluate the utility of the National Surveys of Attitudes and Sexual Lifestyles (Natsal) undertaken in 2000 and 2010, before and after the introduction of the National Chlamydia Screening Programme, as an evidence source for estimating the change in prevalence of Chlamydia trachomatis (CT) in England, Scotland and Wales. Both the 2000 and 2010 surveys tested urine samples for CT by Nucleic Acid Amplification Tests (NAATs). We examined the sources of uncertainty in estimates of CT prevalence change, including sample size and adjustments for test sensitivity and specificity, survey non-response and informative non-response. In 2000, the unadjusted CT prevalence was 4.22% in women aged 18–24 years; in 2010, CT prevalence was 3.92%, a non-significant absolute difference of 0.30 percentage points (95% credible interval −2.8 to 2.0). In addition to uncertainty due to small sample size, estimates were sensitive to specificity, survey non-response or informative non-response, such that plausible changes in any one of these would be enough to either reverse or double any likely change in prevalence. Alternative ways of monitoring changes in CT incidence and prevalence over time are discussed.

The purpose of this work was the molecular study of the virus strain that caused the last measles outbreak in Greece. Twenty-four saliva specimens were obtained from selected patients serologically confirmed as measles cases between December 2005 and March 2006. Measles virus (MV) detection was performed by a nested RT–PCR. The 447-bp segment of the N gene of these MV strains was used for genotyping. The N gene sequences of the Greek MV strains were identical to each other, therefore a phylogenetic tree was constructed using one representative MV (ThesGRE/06). Our data show that the MV strain which caused the 2005–2006 outbreak in Greece belongs to genotype D6, and differs by 0·68% from the New Jersey D6 strain and by 5·5% from the MV vaccine strain Edmonston B (U03656) belonging to genotype A.

Recent publicity concerning congenital toxoplasmosis has generated a demand for serological assessment of pregnant women. Many laboratories are requested to undertake primary screening in these cases. We assessed the latex agglutination test (LAT) findings in 158 specimens with detectable toxoplasma specific IgM derived from pregnant women. The LAT titres ranged from 16 to ≥ 4000 reflecting the variable antibody response observed in acute toxoplasmosis. We recommend that non-reference laboratories test specimens from pregnant women using the LAT at a screening dilution of 1:16 and select all reactive samples for detailed investigation.

A new test, the water agar test, is described that gives a qualitative index of the presence of bacteria that indicate contamination of the cream, poor storage conditions or both of these factors. The method is simple and requires little equipment. The bacteria grow in a film of diluted cream adsorbed on the surface of a non-nutrient base. After incubation at 30 ± 0.5° C. for 18–20 hr., a proteolytic and mucoid colony count is obtained which has the same percentage coefficient of variance as a standard plate count.

An examination of the effect of storage at different temperatures on the types of bacteria present in cream showed that of all the tests done initially, only the water agar test could predict subsequent bacterial growth with any consistency. The multiplication of presumptive coliform organisms occurred even at 3.5° C. Irrespective of the colony count, the methylene blue reduction time was not shorter than 7½ hr. unless the bacteria were in the logarithmic phase of growth when sampled.

A survey was made of the bacterial flora of 188 retail samples of double cream of 15 different brands. The age of the samples varied from freshly separated cream to cream that had been kept in the shop for a day longer than that recommended for sale. The water agar test was compared with the colony count, the presumptive coliform test, a confirmatory coliform count in violet red-bile agar, a lipolytic colony count, a staphylococcal count and the methylene blue reduction test.

1. An antiserum containing antibodies for two unrelated antigens, crystalline egg albumin and crystalline horse serum albumin, has been prepared.

2. In titrations of the antiserum against mixtures of these antigens it has been possible to produce a single zone or two zones of optimal particulation by varying the relative concentrations of the components in the antigenic mixtures. It is evident, therefore, that whilst (a) a single zone does not necessarily indicate a single antigen-antibody system, (b) multiple zones suggest the presence of more than one antigen-antibody system.

We describe the isolation of a new set of phages for typing Staphylococcus epidermidis. One hundred and eighty-two phages were obtained from S. epidermidis strains of human origin. Twelve phages were selected according to their potency and their lytic activity studied. Twenty phages of the Dean and Williams' set were also studied.

Phage-typing was undertaken at 100 × RTD, 1000 × RTD and after heat treatment at 48 °C. When the two sets of phages were compared separately similar figures were obtained. When the two typing sets wrere combined, the percentage of typability for the 182 bacterial strains increased to 29⋅1% using 1000 x RTD and to 75⋅3% after heat treatment.

The increase in pertussis cases in Minnesota in the last decade has been mainly attributed to the switch from whole cell to acellular pertussis [as part of the diphtheria, tetanus and acellular pertussis vaccine (DTaP)]. It is unclear, however, to what degree community-level risk factors also contribute. Understanding these factors can help inform public health policy-makers about where else to target resources. We performed an ecological analysis within Minnesota to identify risk factors at the county level using a Bayesian Poisson generalized linear areal model to account for spatial dependence. Univariate analyses suggested an association between increased pertussis rates at the county level and white maternal ethnicity, being US born, urban counties and average household size. In the multivariable analysis, the rate of pertussis was 1·79 times greater for urban vs. rural counties and 4·75 times greater for counties with a one-person larger average household size. Pertussis rates in counties with higher (i.e. 4+DTaP) receipt in children were 0·97 times lower. Examining county-level factors associated with varying levels of pertussis may help identify those counties that would most benefit from targeted interventions and increased resource allocation.

Dobrava-Belgrade virus (DOBV) is the most pathogenic hantavirus in Europe with a case-fatality rate of up to 12%. To detect changes in risk for humans, the prevalence of antibodies to DOBV has been monitored in a population of Apodemus flavicollis in the province of Trento (northern Italy) since 2000, and a sudden increase was observed in 2010. In the 13-year period of this study, 2077 animals were live-trapped and mean hantavirus seroprevalence was 2·7% (s.e. = 0·3%), ranging from 0% (in 2000, 2002 and 2003) to 12·5% (in 2012). Climatic (temperature and precipitation) and host (rodent population density, rodent weight and sex, and larval tick burden) variables were analysed using Generalized Linear Models and multi-model inference to select the best model. Climatic changes (mean annual precipitation and maximum temperature) and individual body mass had a positive effect on hantavirus seroprevalence. Other possible drivers affecting the observed pattern need to be studied further.

The white pock variant of cowpox virus shows limited growth in chick embryo fibroblasts maintained in arginine-deprived culture medium. Since these conditions inhibit the growth of parental virus, there is a marked increase in the frequency of the white variant in the virus population recovered after passage in the absence of arginine. The variants generated in this system have been characterized by restriction endonuclease analysis of virus DNA in the total DNA recovered from infected cell cultures. Such analysis shows that the white variants arise as deletion mutants of the parental virus, but there was considerable heterogeneity in the restriction patterns of different isolates examined shortly after their generation. Further passage selected white cowpox virus populations with a stable genome configuration comparable with the DNA of pock-purified white variants.

1. Dick tests on 743 Bantu children aged 6–20 years showed 5·0% positive reactors.

2. Throat swabs from 200 urban native children showed 19% carriers of Lancefield's group A Streptococcus haemolyticus.

3. The basis of Bantu immunity to scarlet fever is discussed.

I am indebted to Dr E. H. Cluver, Director, and Dr G. Buchanan, Deputy Director of the South African Institute for Medical Research, for their continued interest in the progress of this work, and I am especially grateful to Dr D. Ordman of this Institute who isolated and typed the streptococci for me. My thanks are also due to Dr Marcus, Kanye, Bechuanaland Protectorate, and to Dr Prestwich and Dr Xuma, of Alexandra Township, for making it possible to examine the requisite number of Bantu children. The travelling expenses involved in this investigation were defrayed by a grant from the National Research Board.

An investigation into the cause of bacterial contamination of bottles of non-injectable water has been reported. A method of monitoring such bottles has also been described. The roles played by autoclave spray-cooling water and inadequate bottle seals in the contamination of fluids have been examined. Possible methods of reducing the risk of contamination are discussed and the design of an improved method of closure of sterile bottled fluids is stressed. Bacteriological examination is shown to be a more accurate index of the true rate of contamination than measurement of dye concentrations of bottle contents.

Among the most prevalent Mycobacterium tuberculosis (Mtb) strains worldwide is the Beijing genotype, which has caused large outbreaks of tuberculosis (TB). Characteristics facilitating the dissemination of Beijing family strains remain unknown, but they are presumed to have been acquired through evolution of the lineage. To explore the genetic diversity of the Beijing family Mtb and explore the discriminatory ability of mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) loci in several regions of East Asia, a cross-sectional study was conducted with a total of 163 Beijing strains collected from registered TB patients between 1 June 2009 and 31 November 2010 in Funing County, China. The isolated strains were analysed by 15-MIRU-VNTR loci typing and compared with published MIRU-VNTR profiles of Beijing strains. Synonymous single nucleotide polymorphisms at 10 chromosomal positions were also analysed. The combination of SNP and MIRU-VNTR typing may be used to assess Mtb genotypes in areas dominated by Beijing strains. The modern subfamily in Shanghai overlapped with strains from other countries, whereas the ancient subfamily was genetically differentiated across several countries. Modern subfamilies, especially ST10, were prevalent. Qub11b and four other loci (MIRU 26, Mtub21, Qub26, Mtub04) could be used to discriminate Beijing strains.