That the number of male births always exceeds that of females is well known to students of vital statistics, but the biological law responsible for the phenomenon has not yet been adequately determined though various theories have been offered in explanation. It has been suggested that it resulted from a high male conception rate which, although modified by an excess mortality of male embryos, nevertheless produced a masculinity of matured births. In more recent times the conclusions drawn by MacDowell & Lord (1925, 1925 a) from their experimental studies with mice have failed to support this view. They claimed that there was no correlation between the pre-natal mortality and the masculinity of live births, that the primary ratio at conception was almost identical with that at birth. These contentions were criticized by Parkes (1923, 1926), who, whilst maintaining the doctrine that the ante-natal mortality of mice “falls preponderatingly upon the males”, stated “that it is quite obvious that a great deal more information is required before any coherent story of the factors governing the sex ratio at birth in the mouse (and all other mammals) can be put together”.

On 14 January 2013, the US Food and Drug Administration (FDA) announced permission for a multiplex nucleic acid test, the xTAG® Gastrointestinal Pathogen Panel (GPP) (Luminex Corporation, USA), which simultaneously detects 11 common viral, bacterial and parasitic causes of infectious gastroenteritis, to be marketed in the USA. This announcement reflects the current move towards the development and commercialization of detection technologies based on nucleic acid amplification techniques for diagnosis of syndromic infections. We discuss the limitations and advantages of nucleic acid amplification techniques and the recent advances in Conformité Européene – in-vitro diagnostic (CE-IVD)-approved multiplex real-time PCR kits for the simultaneous detection of multiple targets within the clinical diagnostics market.

During the period 1989–94, 4620 strains of Streptococcus pneumoniae (4063 from blood and 557 from cerebrospinal fluid), from cases of invasive disease in Denmark, were received for capsular typing and penicillin susceptibility testing. During the study period the incidence of bacteraemic pneumococcal disease increased from 10 to 18 cases per 100000 inhabitants per year. The highest rates were seen in the very young, age less than 5 years (23/100000/year, in 1994), and in the elderly, age greater than 60 years (55/100000/year, in 1994). The annual number of cases of meningitis did not vary.

Overall, 92% (93% blood, 87% CSF) of isolates and 94% of all childhood isolates belonged to the 23 vaccine types. The capsular types occurring most commonly among the 4123 pneumococcal strains from adults were types 1, 4, 14, 6A+6B, 7F, 9V, 3, 12F, and 8 (in order of frequency). The ten most frequently occurring types from children (6A+6B, 18C, 14, 1, 7F, 19F, 9V, 4, and 23F) covered 84% of the cases of bacteraemia and meningitis. Reduced susceptibility to penicillin was rare (< 1%).

The 16S-23S RNA gene intergenic spacers of isolates of Streptococcus equi (n=5), S. zooepidemicus (n=5), S. equisimilis (n=3) and S. dysgalactiae (n=2) were sequenced and compared. There were distinct regions within the spacer, arranged in the order 1–9 for all S. equi and one S. zooepidemicus isolate and 1,2 and 4–9 for the remaining isolates. Region 4 was identical to the tRNAala gene found in the 16S-23S intergenic spacers of other streptococci. Regions 1, 5, 6 and 7 had distinct variations, each conserved in different isolates. However, amongst the intergenic spacers there were different combinations of variant regions, suggesting a role for DNA recombination in their evolution. The intergenic spacer of all isolates of S. equi and one S. zooepidemicus isolate were almost identical. Primers derived from the variant sequences of regions 1 and 5 to 6 were used to group all S. zooepidemicus (n=17) and S. equi (n=5) into 1 of 8 types by polymerase chain reaction; three S. zooepidemicus isolates typed the same as S. equi. S. equi and S. zooepidemicus were clearly distinguishable from S. equisimilis and S. dysgalactiae which had shorter regions 5 and 6 and no region 7. Most homology for the group C sequences was found in previously published sequences for the 16S-23S intergenic spacers of S. anginosis, S. constellatus, S. intermedius, S. salivarius and S. agalactiae. A 75-90 nucleotide length shared with S. anginosus and S. intermedius in opposite orientations in the two main variants of region 6 supported the role for DNA recombination in the evolution of the spacer. The 16S-23S intergenic spacers indicate that S. zooepidemicus was the archetypal species for S. equi and that both are genetically more distant from S. equisimilis and S. dysgalactiae. The intergenic spacer can be used to identify specifically the group C. streptococci and as an epidemiological marker for S. zooepidemicus.

We investigated the effect of social inequalities on the uptake of human papillomavirus (HPV) vaccination, combining data from a feasibility study conducted in 2007–2008 in 2817 secondary schoolgirls in two UK primary-care trusts, with census and child health records. Uptake was significantly lower in more deprived areas (P<0·001) and in ethnic minority girls (P=0·013). The relatively small proportion of parents who actively refused vaccination by returning a negative consent form were more likely to come from more advantaged areas (P<0·001). Non-responding parents were from more deprived (P<0·001) and ethnic minority (P=0·001) backgrounds. Girls who did not receive HPV vaccination were less likely to have received all their childhood immunizations particularly measles, mumps and rubella (MMR). Different approaches may be needed to maximize HPV vaccine uptake in engaged and non-responding parents, including ethnic-specific approaches for non-responders.

By a combination of a swab sampling method, modern cultural techniques and Vi-phage typing, a survey for enteric organisms has been made of the sewerage system of a town of about 10,000 inhabitants.

The location of typhoid and paratyphoid B carriers by systematic swabbing of sewers in accordance with cultural findings has been proved feasible.

Two paratyphoid B carriers and one typhoid carrier were discovered by this method. Evidence was obtained of the presence of at least six other foci of paratyphoid infection in the town.

Paratyphoid bacilh were repeatedly isolated from a river flowing through the town. The possible role of river pollution in the maintenance of endemic enteric infection in the area is discussed.

The methods used in this survey might be applied with advantage to the elucidation of unsolved enteric outbreaks, to the control of food-handling establishments and to epidemiological studies of other infections in which the causative organism gains access to sewage.

We are indebted to Mr R. W. Pinney and Mr W. E. Coles, who did by far the greater part of the work of laying the sewage swabs and sending them to the laboratory; to Mr L. M. Blanchard, Surveyor, Sidmouth U.D.C., for his assistance with the preparation of maps of the area; to Dr A. Felix for his kindness in typing the enteric strains isolated; and to Mr R. N. Brown and Mr S. Barlow for much assistance in the development of cultural techniques.

The number of patients with severe invasive group-G streptococcal (Streptococcus dysgalactiae subsp. equisimilis) infections has been increasing in Japan. The emm genotypes and SmaI-digested pulsed-field gel electrophoresis DNA profiles were variable among the strains isolated, suggesting there has not been clonal expansion of a specific subpopulation of strains. However, all strains carried scpA, ska, slo and sag genes, some of which may be involved in the pathogenesis of the disease.

Ticks of the Ornithodoros moubata complex were collectedfrom domestic pig sties and dwelling houses, and from a warthog habitat, and tested for the presence of African swine fever (ASF) virus. Collections were made in 9 of the 24 districts of Malawi, these being primarily the districts in which O. moubata is most numerous. ASF virus was isolated from ticks collected in both domestic pig sties and houses in certain villages in Mchinji district where ASF outbreaks had recently occurred. Mchinji district is in the centre of a large ASF enzootic area which stretches into other districts of Malawi and also into Zambia and Mozambique. The high titre of virus in some of the ticks demonstrates that O. moubata can act as a virus reservoir and potential vector of disease in the field situation in Malawi.

A common source outbreak of small round structure virus (SRSV) gastroenteritis affected 81 patients and 114 staff in four hospitals served by one central hospital kitchen. Eating salad items was found to be significantly associated with illness. In a cohort study of a staff buffet function eating turkey salad sandwiches was associated with illness (relative risk = 2·4; 95% CI = 1·4–4·1; P = 0·003), and a case control study of patients in one hospital showed an odds ratio of 6·6 (95% CI = 1·0–71·6; P = 0·04) for eating tuna salad and becoming ill. One of two food handlers who prepared the salads became ill the day following food preparation; she also had a young child at home who had been ill with a gastrointestinal illness during the previous two days. Contamination of food by mechanical transmission of the virus from the child via clothes and hands of the mother, or pre-symptomatic faecal excretion in the mother are possible explanations of contamination of food.

A local milk-borne outbreak of 85 cases of sore throat with cervical lymphadenitis, a third of whom later developed acute glomerulonephritis as a complication, is described. Renal involvement was shown by Volhard's criteria, filtered fraction data and renal biopsy findings. From lymph-node biopsies from patients, from the pharyngeal exudate of patients and carriers, and from three samples of cow's milk, 16 strains of beta-haemolytic streptococci of Lancefield group C, type zooepidemicus subtype lactose-positive, were isolated.

The aetiological role of the streptococcus isolated in this outbreak was confirmed by autoserodiagnosis (precipitation tests with Lancefield's antigens and patients' sera) which in this case proved more valuable than antistreptolysin-O titration as evidence of infection.

Two of the 85 patients, 7 months after the acute phase of illness, show nephrotic oedema and hypertension as chronic sequelae.

We are pleased to express our gratitude to Dr M. T. Parker and Dr W. R. Maxted for much advice, and confirmation of our serological and biochemical findings.

We collected diarrhoea specimens in two hospitals in southern Thailand in 1999 to examine whether infection by the Vibrio parahaemolyticus pandemic clone is prevalent. V. parahaemolyticus was isolated from 317 specimens. Seventy-six per cent of the isolated strains had the pandemic clone-specific characteristics (tdh+, trh−, and an unique toxRS sequence detectable by GS-PCR) and an associated characteristic (the ORF8 sequence of f237 phage). These strains belonged to the three pandemic servovars with the O3[ratio ]K6 strains being dominant and three other serovars (O1[ratio ]K25, O1[ratio ]K41 and O4[ratio ]K12). We also found O1[ratio ]K25 and O1[ratio ]K41 strains with the pandemic clone-specific characteristics among the strains isolated from the international travellers who left Thailand and three other Asian countries between 1998 and 1999, verifying pandemic potential of these strains. The results demonstrate prevalence of infection by the pandemic clone in southern Thailand and suggest emergence of various serovariants in this area and their implication in international spread.

Weaner pigs (n = 72) were fed 1 of 4 diets. These were based on either cooked rice and animal protein, cooked rice and lupin, wheat and lupin, or wheat and animal protein. Twenty-six of the pigs were slaughtered after 1 month. Those fed the highly digestible cooked rice and animal protein diet had drier colonic contents and faeces, lighter large intestines, and the contents of their large intestines had increased pH values and decreased total VFA concentrations. The other 46 pigs were orally challenged with broth cultures of Serpulina hyodysenteriae, and were monitored for faecal excretion of the spirochaetes, and for the development of swine dysentery (SD). None of 18 pigs fed the cooked rice and animal protein diet developed colonic changes or disease, whereas most pigs on the other diets developed mucohaemorrhagic colitis and dysentery. The reduced fermentation that occurred in the large intestines of pigs fed cooked rice and animal protein was associated with a subsequent failure of colonization by S. hyodysenteriae, and resultant protection against SD.

A survey of ABO blood groups, secretor status and smoking habits among 389 students and staff of a school in which there was an outbreak of meningococcal disease found no difference in the distribution of the ABO blood groups but a significantly higher proportion of non-secretors (37·6%) in the population examined compared with that reported for previous surveys of the neighbouring population in Glasgow (26·2%) (P < 0·0005). There was also a significantly higher proportion of non-secretors among carriers of meningococci (47%) compared with non-carriers (32%). Increased carriage of meningococci among non-secretors might contribute to the increased susceptibility of individuals with this genetic characteristic to meningococcal disease observed in previous studies. Although passive exposure to cigarette smoke has been associated with meningococcal disease, there was no association between passive smoking and carriage. There was, however, a significant association between active smoking and carriage.

During October 1996, an outbreak of Escherichia coli O157[ratio ]H7 infections among Connecticut residents occurred. An epidemiologic investigation included enhanced surveillance and a case-control study. Clinical isolates of Escherichia coli O157[ratio ]H7 were typed by pulsed-field gel electrophoresis (PFGE). Implicated cider samples were analysed by culture and polymerase chain reaction (PCR). Consumption of implicated cider was associated with illness; (matched odds ratio = undefined, 95% confidence interval = 3·5–infinity). Ultimately, a total of 14 outbreak-associated patients were identified. All isolates analysed by PFGE yielded the outbreak-associated subtype. Escherichia coli O157[ratio ]H7 was not cultured from three cider samples; PCR analysis detected DNA fragments consistent with Escherichia coli O157[ratio ]H7 in one. This outbreak was associated with drinking one brand of unpasteurized apple cider. PFGE subtyping supported the epidemiologic association. PCR analysis detected microbial contaminants in the absence of live organisms. Washing and brushing apples did not prevent cider contamination.

During the 1984 cholera epidemic in Mali, 1793 cases and 406 deaths were reported, a death-to-case ratio of 23%. In four affected villages, the mean clinical attack rate was 17·5 and 29% of affected persons died. In 66% of cases the illness began more than 48 h after the village outbreak began, when supplies from outside the village were potentially available. Deaths occurred because patients failed to seek care or received only limited rehydration therapy when they did. Case-control studies identified two routes of transmission: drinking water from one well in a village outside the drought area, and eating left-over millet gruel in a droughtaffected village. Drought-related scarcity of curdled milk may permit millet gruel to be a vehicle for cholera. Cholera mortality in the Sahel could be greatly reduced by rapid intervention in affected villages, wide distribution of effective rehydration materials, and educating the population to seek treatment quickly.

Linked administrative population data were used to estimate the burden of childhood respiratory syncytial virus (RSV) hospitalization in an Australian cohort aged <5 years. RSV-coded hospitalizations data were extracted for all children aged <5 years born in New South Wales (NSW), Australia between 2001 and 2010. Incidence was calculated as the total number of new episodes of RSV hospitalization divided by the child-years at risk. Mean cost per episode of RSV hospitalization was estimated using public hospital cost weights. The cohort comprised of 870 314 children. The population-based incidence/1000 child-years of RSV hospitalization for children aged <5 years was 4·9 with a rate of 25·6 in children aged <3 months. The incidence of RSV hospitalization (per 1000 child-years) was 11·0 for Indigenous children, 81·5 for children with bronchopulmonary dysplasia (BPD), 10·2 for preterm children with gestational age (GA) 32–36 weeks, 27·0 for children with GA 28–31 weeks, 39·0 for children with GA <28 weeks and 6·7 for term children with low birthweight. RSV hospitalization was associated with an average annual cost of more than AUD 9 million in NSW. RSV was associated with a substantial burden of childhood hospitalization specifically in children aged <3 months and in Indigenous children and children born preterm or with BPD.

The aim of the study was to define the prevalence of verotoxin-producing Escherichia coli (VTEC) in cattle and pigs in a Hong Kong abattoir. Faecal and carcass samples collected from 986 cattle and 487 pigs from an abattoir were tested for verotoxin (VT) by PCR and cytotoxicity assays. VTEC was isolated from 41·5 and 1·8 % of cattle faecal and carcass samples and from 2·1 and 0·2 % of porcine faecal and carcass samples, respectively. Amongst 409 VTEC isolates from cattle, 9 were serotype O157:H7 and eaeA+. The most prevalent vt genotype among bovine VTEC was vt1+vt2+ (73·8 %) and in porcine VTEC was vt2e+ (30 %). None of the porcine VTEC isolates and 9·3 % of the bovine VTEC isolates was eaeA+. The non-O157 serogroup VTEC isolates carrying eaeA and EHEC-hlyA belonged to serogroups O172, O15, O84, O91, O110 and O121. The local dietary preference for pork or chicken (rather than beef ), the low VTEC carriage in pigs, the rarity of additional virulence factors (eaeA) in VTEC isolated from cattle may explain the apparently low incidence of human diarrhoeal disease associated with VTEC in Hong Kong hitherto. However, the presence of non-O157 VTEC strains carrying the eaeA virulence marker in cattle highlights the fact that sole reliance on sorbitol-MacConkey agar for screening human VTEC isolates may underestimate the human disease burden. The changing dietary habits of the population in Hong Kong reinforce the need for continued vigilance.

Gastroenteritis (GE) is among the most common illnesses of humans but the burden of disease, its epidemiology, and the distribution of pathogens in adults have not been fully examined. This information is needed to plan prevention strategies particularly for high-risk groups. This study is a retrospective analysis of data from the National Hospital Discharge Survey for the years 1979 through 1995 which describes the disease burden and epidemiology of hospitalizations associated with GE among adults in the United States. Diarrhoea was listed as a diagnosis on an average of 452000 hospital discharges per year representing 1·5% of all hospitalizations among adults. The annual number of GE hospitalizations has decreased by 20% from approximately 500000 in 1979 to 400000 in 1995. The aetiology of 78% of cases coded as GE was undetermined. Until the aetiology of disease can be better established, specific strategies for prevention cannot be developed.

(1) If B. coli be subcultured into another sample of the same medium when growing at full pace, it will continue to grow at the same pace.

(2) If the maximum rate of growth be interrupted by a short application of cold, growth will recommence without lag on the temperature being raised. If the cold be long continued, lag will tend to reappear.

(3) Differences in the size of inoculum have practically no effect on lag in the case of large inoculums, in the case of small ones, on the other hand, diminution of the seeding has the effect of lengthening lag, and this lengthening effect is more marked the smaller the seedings become.

(4) Lowering the temperature lengthens the lag. The effect is very similar to the effect on growth.

(5) The older a parent culture (within limits) the longer the lag.

(6) The length of lag varies with the medium even if adaptation has been arranged for beforehand.

(7) Heat-stable products in B. coli cultures on peptone water have, in the case of overnight cultures, but little effect on lag.

(8) After washing the bacteria for two hours with saline in order to remove possible inhibiting agents, it was found that the lag, on subculture, still occurred and was indeed slightly longer.

(9) If a peptone water culture of B. coli be centrifuged, it is found that the few bacteria remaining in the supernatant commence to grow again at a quick rate but not without a period of lag.

This investigation was undertaken to provide detailed information on the epidemiology of human parvovirus B19 (B19) infection during pregnancy and childhood in the western part of Germany. Between 1997 and 2004, 40 517 sera from pregnant women aged 17–45 years and 6060 sera from children and young adults were tested for B19 IgG and IgM in our laboratory. In pregnant women, both the history of a ‘specific’ (OR 7·7, 95% CI 5·2–11·4) and a ‘non-specific’ rash (OR 3·3, 95% CI 1·5–7·1) was predictive for B19 IgM positivity. The B19 IgG prevalence was 69·2% (4097/5924) in a subgroup of asymptomatic pregnant women screened for B19 antibodies. In children, the age-specific IgG-positivity rate increased from 12·2% (66/541) at 2 years of age to 71·9% (396/551) in those older than 10 years. In conclusion, the prevalence of B19 IgG in pregnant women from the western part of Germany is higher then previously reported. Contact with children aged 3–10 years is a major risk factor for exposure to B19. Pregnant women with the history of a ‘non-specific’ rash should also be evaluated for acute B19 infection.