The growth of Salmonella enteritidis PT4 in albumen around an intact yolk was governed by the age of the egg on inoculation. In the majority of eggs, held at 20° C, the bacterium was unable to grow rapidly until eggs had been stored for approximately 3 weeks. The multiplication of S. enteritidis in stored eggs appeared to be associated with alterations to the yolk membrane which allowed the bacterium to either invade the yolk or obtain nutrients from it. The rate at which egg contents change to permit the growth of S. enteritidis would appear to be temperature related and took place more rapidly when eggs were stored under conditions where temperatures fluctuated and, on occasions, reached 30° C.

In an investigation of impetigo among troops, carried out in 1941, nearly half of the strains of Staphylococcus aureus isolated from the lesions had the ability to inhibit the growth of corynebacteria on solid media. A much smaller proportion of strains from other superficial lesions and from nose and throat swabs had this ability, and strains from deep suppurative lesions were uniformly negative.

Three-quarters of Staph. aureus strains isolated from schoolchildren with impetigo in Lancashire in 1953 and early 1954 were of one variety, which could be denned by its susceptibility to typing phages (‘type 71’).

Nearly 90 % of ‘type 71’ staphylococci, and very few others, produced a narrow, sharp zone of inhibition of Corynebacterium diphtheriae mitis on solid media.

A small number of other staphylococci, mainly non-typable or unclassifiable strains, produced a wider, hazy zone of inhibition.

The majority of the impetigo staphylococci were penicillin-resistant, and most of the resistant strains were members of ‘type 71’. However, ‘type 71’ gave rise to only a small proportion of the penicillin-resistant hospital infections occurring in the same district at the same time.

Three-quarters of the Str. pyogenes strains from impetigo lesions belonged to one of two groups of closely related serological types, one of which was rarely encountered in other situations.

The specific humoral immune response of 17 volunteers to infection with human rhinovirus type 2 (HRV-2) has been measured both by neutralization and by ELISA. Six volunteers who had HRV-2-specific antibodies in either serum or nasal secretions before HRV-2 inoculation were resistant to infection and illness. Of the remaining 11 volunteers who had little pre-existing HRV-2-specific antibody, one was immune but 10 became infected and displayed increases in HRV-2-specific antibodies. These antibodies first increased 1–2 weeks after infection and reached a maximum at 5 weeks. All six resistant volunteers who had high pre-existing antibody and eight of the volunteers who became infected maintained their HRV-2-specific antibody for at least 1 year. At this time they were protected against reinfection. Two volunteers showed decreases in HRV-2-specific antibodies from either serum or nasal secretions. They became infected but not ill after HRV-2 inoculation 1 year later.

Dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) are reportable diseases, the third most common causes for hospitalization of children in Thailand. Data collected from the Ministry of Public Health were analysed for trends. Rates of DHF increased in Thailand until 1987 when the largest epidemic ever, 325/100000 population, was recorded. Whereas the disease used to be confined to large cities, the rate is now higher in rural (102·2 per 100000) than urban areas (95·4 per 100000 in 1997). The age of highest incidence has increased, and the age group most severely affected is now those 5–9 years old (679/100000 in 1997). The case fatality rate has decreased with improved treatment and is now only 0·28%.

Helicobacter pylori infection plays a role in the development of chronic gastritis, peptic ulcer and gastric cancer, yet the route of transmission into susceptible hosts remains unknown. Studies employing microbiological techniques have demonstrated that H. pylori has the ability to survive when introduced into water and that H. pylori is present in water and other environmental samples all over the world. Epidemiological studies have shown that water source and exposures related to water supply, including factors related to sewage disposal and exposure to animals, are risk factors for infection. This review describes the microbiological and epidemiological evidence for, and proposes a model of, waterborne H. pylori transmission outlining important features in the transmission cycle. In the model, humans and animals shed the bacteria in their faeces and the mechanisms for entry into water, and for survival, ingestion and infection are dependent upon a range of environmental influences. Verification of the proposed model pathways has important implications for public-health prevention strategies.

H9N2 is the most widespread avian influenza virus subtype in poultry worldwide. It infects a broad spectrum of host species including birds and mammals. Infections in poultry and humans vary from silent to fatal. Importantly, all AIV, which are fatal in humans (e.g. H5N1, H7N9) acquired their ‘internal’ gene segments from H9N2 viruses. Although H9N2 is endemic in the Middle East (ME) and North Africa since the late 1990s, little is known about its epidemiology and genetics on a regional level. In this review, we summarised the epidemiological situation of H9N2 in poultry and mammals in Iran, Iraq, Kuwait, Qatar, United Arab Emirates, Oman, Bahrain, Yemen, Saudi Arabia, Jordan, Palestine, Israel, Syria, Lebanon, Turkey, Egypt, Sudan, Libya, Tunisia, Algeria and Morocco. The virus has been isolated from humans in Egypt and serosurveys indicated widespread infection particularly among poultry workers and pigs in some countries. Some isolates replicated well in experimentally inoculated dogs, mice, hamsters and ferrets. Insufficient protection of immunised poultry was frequently reported most likely due to concurrent viral or bacterial infections and antigenic drift of the field viruses from outdated vaccine strains. Genetic analysis indicated several distinct phylogroups including a panzootic genotype in the Asian and African parts of the ME, which may be useful for the development of vaccines. The extensive circulation of H9N2 for about 20 years in this region where the H5N1 virus is also endemic in some countries, poses a serious public health threat. Regional surveillance and control strategy are highly recommended.

During December 2009, over 200 individuals reported gastrointestinal symptoms after dining at a North Carolina restaurant. An outbreak investigation included a case-control study of restaurant patrons, a secondary household transmission study, environmental assessment of the restaurant facilities and operations, and laboratory analysis of stool and food samples. Illness was primarily associated with consumption of steamed oysters (odds ratio 12, 95% confidence interval 4·8–28) and 20% (8/41 households) reported secondary cases, with a secondary attack rate of 14% among the 70 susceptible household contacts. Norovirus RNA was detected in 3/5 stool specimens from ill patrons; sequencing of RT–PCR products from two of these specimens identified identical genogroup II genotype 12 sequences. Final cooked temperatures of the steamed oysters were generally inadequate to inactivate norovirus, ranging from 21°C to 74°C. Undercooked contaminated oysters pose a similar risk for norovirus illness as raw oysters and household contacts are at risk for secondary infection.

From February to July of 1994, 328 faecal samples from 32 herds were collected and verotoxin-producing Escherichia coli (VTEC) found on 84% of the farms. The proportion of animals infected varied from 0–63%. VTEC were recovered from 52 (20%) of 257 cows and from 16 (23%) of 71 calves. Although the VTEC belonged to 25 different serogroups, 7 (O8. O20, O22, O77, O113, O126 and O162) accounted for 46% of strains. Nearly 45% of the 83 bovine VTEC strains belonged to serogroups associated with haemorrhagic colitis and haemolytic uraernic syndrome in humans. However, only 2 (2%) of 83 VTEC strains isolated from cattle belonged to enterohaemorrhagic E. coli (EHEC) serotypes (O26:H11 and O157:H7), and only 8 (10%) were positive for the attaching and effacing E. coli (eae) gene sequence. Polymerase chain reaction (PCR) showed that 17 (20%) of VTEC strains carried VT1 genes. 43 (52%) possessed VT2 genes, and 23 (28%) carried both VT1 and VT2 genes. Characterization of VTEC isolates revelated a heterogeneous population in terms of serogroup and toxin type in the positive herds. This study confirms that healthy cattle are a reservoir of VTEC, but, the absence of eae genes in most bovine VTEC strains suggests that they may be less virulent for humans than eae-positive EHEC.

The first recognized outbreak of haemorrhagic colitis due to Escherichia coli O 157. H7 in the United Kingdom affected at least 24 persons living in East Anglia over a 2-week period. Theillnesses were characterized by severe abdominal pain and bloody diarrhoea of short duration. Eleven patients were admitted to hospital and there was one death. Patients were mainly adult women who had not eaten out of the home in the 2 weeks before onset. Unlike previously reported outbreaks hamburgers were not the vehicle of infection, and a case-control study suggested that handling vegetables, and particularly potatoes, was the important risk factor.

When fresh meat, or blood, is boiled the colour changes from the red of oxyhaemoglobin to a dull, brownish colour. The change of colour is due to splitting up of oxyhaemoglobin into coagulated proteid and haematin, which are precipitated. The dark colour of haematin, mixed with the white of coagulated proteid, gives the dull brown. When, however, meat has been salted, it has a characteristic red colour when cooked. It is evident, therefore, either that ordinary haematin is not split off from the oxyhaemoglobin, or that the colour of the haematin is masked by the presence of another pigment.

Fomites may play a role in the transmission of rotavirus infections, and in view of this, 27 disinfectants were evaluated for their ability to inactivate human rotavirus (HRV) on contaminated non-porous inanimate surfaces. Disks of stainless steel, glass and two types of plastics were contaminated with about 107 plaque-forming units of HRV suspended in faecal matter. The inoculum was allowed todry and an equal volume of the product under test was applied to the contaminated surface. After contact for 1 min, the action of the disinfectant was stopped by dilution. Surviving infectious virus on the disks was determined by plaque assay in MA-104 cells. A product was considered to be effective if itcould reduce the virus titre by at least 3 log10. Only 33·3% (9/27) of the formulations tested proved to be effective. Further testing of the effective products, which included antiseptics, instrument soaks and hard-surface disinfectants, showed that all of them could, in fact, reduce the virus titre on contaminated surfaces by at least 6 log10. These findings show the relative resistance of HRV to a widerange of chemical disinfectants in common use, and also emphasize the need for a more thorough evaluation of the virucidal potential of formulations regularly employed in attempts to prevent and control outbreaks of rotaviral diarrhoea.

Serological tests are very frequently used in epidemiological surveys of leishmaniasis and other parasitoses. Their sensitivity and specificity are generally defined with respect to parasitism and diseases, rather than infection. The reason is that known positives are those individuals most likely to yield parasites, or who have distinctive clinical signs, and concomitantly high antibody titres. This paper investigates the performance of one serological method, the indirect fluorescent antibody test (IFAT), in detecting Leishmania infantum infection during an intensive 2-year cohort study of dogs in southern France. The results show that sensitivity and specificity with respect to infection can be simultaneously high, but maximum sensitivity is probably <80%, and lasts for a relatively short period of 2–3 months after a lengthy incubation period. The IFAT gave the incidence of infection as 18–65% in the first year, whereas the best estimate of incidence based on parasite isolation and clinical observation was 72%. But data from the second year suggest that the 72% was itself an underestimate. We argue that, during epidemiological surveys, the IFAT in particular, and serological tests for leishmania in general, will underestimate prevalence, incidence and hence the scale of the control problem. However, there is evidence that tests for canine leishmaniasis employing high threshold titres will identify the most infectious animals, allowing selective treatment or culling of those which contribute disproportionately to transmission.

A complement fixation test with rabbit antisera was used to differentiate 82 cultures of Mycoplasma from man, mammalian cell cultures, laboratory rats and mice, cattle, goats, poultry, embryonated eggs and sewage.

Seventeen serotypes were distinguished, 5 from man, 1 from mammalian cell cultures, 4 from rats and mice, 4 from cattle and goats, 2 from poultry and one saprophytic. Most of these corresponded to recognized species of Mycoplasma, but 1 of human origin (represented by 1 strain, Navel), and 1 from tissue cultures (5 strains), may represent new species. R38, one of the serotypes from rats, could be distinguished from the species M. arthritidis, but is probably an antigenic variant rather than a distinct species. Two species hitherto recognized as distinct, M. arthritidis and M. hominis type 2, could not be distinguished and appear to constitute a single species. These findings illustrate the necessity, from the viewpoint of taxonomy, of comparing mycoplasma strains by serological methods.

The serotypes of human and animal origin were largely host-specific. Exceptions were the inclusion of M. arthritidis from rats and M. hominis type 2 from man in a single serotype, the finding of a bovine organism among the strains isolated from goats and of a saprophytic strain in a rat.

In relation to the aetiology of disease in man and animals, the isolation of an endogenous Mycoplasma from embryonated eggs used to passage infective material illustrates the importance of identifying these organisms serologically. The demonstration of mixed mycoplasma infections in lesions in two rats shows the necessity of adequately purifying all cultures of Mycoplasma before examination.

I would like to thank those workers mentioned in Table 1 who kindly provided the cultures which they isolated. In addition I wish to thank the following who sent cultures: Prof. A. C. Ruys and Dr D. Herderscheê (Amsterdam) for G2, Prof. H. E. Morton (Philadelphia) for Campo and 07, Dr D. G. ff. Edward (Beckenham) for Campo (PG27), M. bovigenitalium (PG11), M. iners, and M. gallinarum, Dr R. G. Wittler for H606 and Miss A. G. Newnham for A36, TU, PSU4 and TC727.

My thanks are also due to Dr L. H. Collier of this Institute, Dr G. W. Csonka (London), Prof. A. E. Macdonald (Aberdeen), Dr J. Payne (Edmonton, Alberta), Mr A. A. Tuffrey (Carshalton) and Dr D. Weisinger (Basle) who provided material from which PPLO were isolated. I gratefully acknowledge all the information so generously supplied by these workers about the strains or material provided.

I am indebted to Miss A. G. Newnham for carrying out an agglutination test on the avian strains.

Part of this work was carried out by the author under the author aegis of the Medical Research Council Working Party on Non-Specific Urethritis with the aid of a grant from the U.S. Public Health Service.

Rotaviruses are a major cause of hospitalizations for acute gastroenteritis in developed countries. This review shows the burden of rotavirus disease in <5-year-old children in Europe. An estimated 72000–77000 hospitalizations for community-acquired rotavirus disease occur annually in the 23 million under-fives living in the European Union (EU-25), with a median cost of €1417 per case. Annual hospitalization incidence rates range from 0·3 to 11·9/1000 children <5 years old (median 3/1000). The median proportion of hospital-acquired rotavirus disease among all cases of hospitalization for rotavirus disease is estimated to be 21%. Countries of the EU-25 require information on the burden of rotavirus disease to support introduction of rotavirus vaccines. Data on cases treated at home, medical visits, and emergency wards as well as rotavirus-associated deaths are limited. To fully evaluate the impact and effectiveness of rotavirus vaccination programmes in Europe, additional epidemiological studies will be critical and desirable.

During the investigation of a number of epidemics of Clostridium welchii food poisoning (Hobbs, Smith, Oakley, Warrack & Cruickshank, 1953) the opportunity arose of examining some 500 different strains of Cl. welchii for toxigenicity. Work on so large a scale made it essential to develop a routinefor this purpose, and after several trials we devised the folio whig sequence of tests, which have proved entirely satisfactory in our hands, and may be of interest to others.

The objective was to describe the current epidemiology and trends in New Zealand human leptospirosis, using descriptive epidemiology of laboratory surveillance and disease notification data, 1990–8. The annual incidence of human leptospirosis in New Zealand 1990–8 was 4·4 per 100000. Incidence was highest among meat processing workers (163·5/100000), livestock farm workers (91·7), and forestry-related workers (24·1). The most commonly detected serovars were Leptospira borgpetersenii serovar (sv.) hardjo (hardjobovis) (46·1%), L. interrogans sv. pomona (24·4%) and L. borgpetersenii sv. ballum (11·9%). The annual incidence of leptospirosis declined from 5·7/100000 in 1990–2 to 2·9/100000 in 1996–8. Incidence of L. borgpetersenii sv. hardjo and L. interrogans sv. pomona infection declined, while incidence of L. borgpetersenii sv. ballum infection increased. The incidence of human leptospirosis in New Zealand remains high for a temperate developed country. Increasing L. borgpetersenii sv. ballum case numbers suggest changing transmission patterns via direct or indirect exposure to contaminated surface water. Targeted and evaluated disease control programmes should be renewed.

The mechanism causing viable Francisella tularensis to lose virulence in aerosols has been investigated. Fully virulent organisms were found to be encapsulated and avirulent organisms from aged aerosols, decapsulated. Capsules were also removed by suspension of F. tularensis in hypertonic sodium chloride. The resulting naked, but viable, organisms were predominantly avirulent for guinea-pigs challenged intraperitoneally. Capsular material and cell walls were found to contain large amounts of lipid, about 50 and 70% (w/w) respectively, and to differ in lipid and sugar composition. Isolated capsular material was not found to contain a lethal toxin for mice or guinea-pigs, or to induce an immunological response in these animals to fully virulent F. tularensis.

The high morbidity and mortality of necrotizing fasciitis (NF) supports the need for epidemiological studies to characterize the disease and identify patient factors associated with adverse outcomes. A multi-site medical record review of patients diagnosed with NF was performed (n=80, mortality 15%). Variables collected were hypothesized to have association with adverse outcomes from NF, and multivariable analysis was used to detect any such association in this population. Select factors associated with mortality included evidence of underlying conditions (P=0·002), advanced age (P=0·04), young age (P=0·03), and evidence of sepsis (P=0·006). Select factors associated with amputation included diabetes mellitus (P=0·006), evidence of underlying conditions (P=0·03), and cutaneous gangrene noted on admission (P=0·006). These findings demonstrate the important association of NF and extremes of age with mortality and morbidity and support the value of early suspicion with prompt diagnosis and treatment in order to prevent adverse outcomes since the associated risk factors are not immediately modifiable.

In order to assess the feasibility of environmental poliovirus surveillance, known amounts of poliovirus type 1, strain Sabin, were flushed into the sewage network of Helsinki. Grab specimens collected at a remote downstream location and concentrated about a 100-fold revealed infectious poliovirus on four successive days in all three separate experiments. As for concentration, a simple two-phase separation method was found to be at least as useful as a several-fold more resource-demanding polyethylene glycol (PEG) precipitation method. Recovery of the introduced virus was remarkably high (more than 10%). Using the current system, it might be possible to detect poliovirus circulation in a population of 700 000 people by examining a single 400 ml sewage specimen, if 1 out of 10000 inhabitants were excreting the virus. It is concluded that environmental surveillance is a sensitive approach to monitor silent poliovirus circulation in populations served by a sewage network.

The role of broiler eggs in the transmission of Campylobacter jejuni to broiler grow-out flocks was investigated. Six breeder flocks supplying broiler eggs to hatcheries were examined for cloacal carriage of C. jejuni. Of 240 birds tested, 178 (74%) were C. jejuni-positive. Eggs from these birds examined for C. jejuni penetration of the egg shell indicated that 185 of 187 were campylobacter-free. Eggs from breeder flocks of unknown C. jejuni status were also examined for C. jejuni shell penetration. C. jejuni was not isolated from 142 eggs examined. A further 193 hatchery eggs incubated and hatched in the laboratory were campylobacter-free. Six farms containing the progeny of C. jejuni-positive breeder flocks were monitored. Eight hundred and forty birds from 14 flocks m these grow-out farms were campylobacter-free during their 6-week grow-out period. Experimental egg-penetration studies indicated that C. jejuni transmission via the egg is not easily effected. Of 257 eggs surface-challenged with C. jejuni, 162 hatched; all were campylobacter-free. Of 167 eggs injected with C. jejuni, 12 hatched; 2 of these were colonized with C. jejuni. Our data do not support a role for vertical transmission of C. jejuni in commercial broiler production.