In his book, Floating Matter of the Air, John Tyndall (Tyndall, p. 262) quotes from Robert Boyle's ‘Essay on the Pathological Part of Physik’ ‘that he who thoroughly understands the nature of ferments and fermentations shall probably … give a fair account of divers phenomena of several diseases, which will perhaps be never properly understood without an insight into the doctrine of fermentations'. It was more than a century and a half before the first part of this suggestion was fulfilled, after which the unravelling of the causes of infective diseases proceeded rapidly. In 1836 de la Tour and, almost simultaneously, Schwann (Tyndall, p. 7) discovered, in yeast, the agent of fermentation as a living organism which reproduced itself in endless succession. Schwann also observed that putrefaction in meat broth did not set in if this was kept in contact, not with ordinary air, but with air which had been previously brought to a high temperature.

In November 1986 a large-scale survey was undertaken in the Gloucestershire town of Stonehouse during an outbreak of meningococcal disease due to group B type 15 subtype Pl. 16 sulphonamide-resistant strains. There were 15 cases in Stonehouse residents during the 4 years from April 1983, an annual attack rate of 56·5 per 100000. Four secondary cases occurred despite rifampicin prophylaxis. The objectives of this community survey were to investigate patterns of meningococcal carriage, transmission and immunity and to determine the proportion of non-secretors of blood group antigens in the Stonehouse population find amongst meningococcal carriers. A total of 6237 subjects participated including 75% of the 6635 Stonehouse residents. Over 97% of the participants provided all three of the requested specimens – nasopharyngeal swabs, saliva and blood samples.

The co-operation between the many organizations involved in the detailed preliminary planning was instrumental in the success of the survey; in particular the value of effective collaboration between Departments of Community Medicine and Microbiology and of the Public Health Laboratory Service network of laboratories in undertaking investigations of this size and type was clearly demonstrated.

A total of 6234 nasopharyngeal swabs was collected during a survey of the population of Stonehouse, Gloucestershire in November 1986 as part of an investigation into an outbreak of meningococcal disease. The overall meningococcal carriage rate was 10·9%. The carriage rate rose with age from 2·1% in the 0- to 4-year-olds to a peak of 24·5% in the 15- to 19-year-olds, and thereafter declined steadily with age. Male carriers outnumbered female carriers of meningococci by 3:2. Group B (or non-groupable) type 15 sulphonamide-resistant strains which had caused the outbreak were isolated from 1·4% of subjects. The age distribution of carriers of these strains was similar to that of other meningococci apart from an additional peak in the 5–9-year age group and a more rapid decline in carriage with increasing age. Variations in the carriage rates of the outbreak strain were seen in children attending different schools and in the residents of different areas of the town. The low carriage rate of these strains in a community during a prolonged outbreak supports the hypothesis that these organisms are less transmissible but more virulent than other strains of pathogenic meningococci.

Carriage of Neisseria lactamica, which is thought to be important in the development of meningococcal immunity, was most frequent in children under the age of 5 years and was six times commoner in this age group than carriage of Neisseria meningitidis. In older children and adults female carriers of N. lactamica increasingly outnumbered males in contrast to the male preponderance observed with meningococcal carriage.

Multiply- and methicillin-resistant Staphylococcus aureus (MRSA) strains have been isolated from five small outbreaks of nosocomial infection in five different hospitals. The MRSA were typed by phage patterns, biochemical traits, resistance phenotypes and plasmid patterns. Three different groups of strains can be distinguished. The MRSA from three outbreaks in one country share identical characters.

Phage typing by the use of the International Basic Set for Phage Typing staphylococci as well as experimental phages does not completely discriminate between the strains. Attribution of several resistance determinants to plasmids in two of the described strain groups proved valuable for strain differentiation.

These multiply-resistant strains are sensitive to vancomycin and to rifampicin.

Fifty-four strains of Escherichia coli belonging to serogroup O 157 were examined for the production of Vero cytotoxins VT1 and VT2, and for other properties such as plasmid content, resistance to antimicrobial agents and colicin production. Twenty-six strains from cases of diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome in humans produced VT. By serum neutralization tests and hybridization with DNA probes for VTl or VT2, three classes were recognized which produced either VTl alone or VT2 alone or both VTl and VT2. These strains were of H type 7 or non-motile. The strains producing VT were sensitive to all the antimicrobial agents tested, and all carried at least one plasmid which had a molecular weight of c.60 × 106. Seven strains of porcine origin and 21 strains of human origin did not produce VT or hybridize with either DNA probe. None of these strains was of H type 7. Of the 21 human VT” strains, 17 were of extraintestinal origin and 18 were of H type 45. Twenty-three of the 28 VT” strains were resistant to at least one antimicrobial agent.

An analysis of the serological and biochemical typing results of 925 clinical isolates of klebsiella revealed that biotyping and serotyping of klebsiella could replace each other for epidemiological purposes. The combination of both typing methods provided even more epidemiological information in analysing clusters of particular serotypes and biotypes in time. Clustering serotypes, mainly of neonatal origin, were nearly uniformly more resistant to the antibiotics in common use than other serotypes. Biotyping as well as serotyping of klebsiella isolates recovered from environmental surveys in the neonatal ward showed that epidemic and non-epidemic klebsiella isolates could occasionally be cultured from the environment and from the staff.

A total of 100 tropical aquaria from six pet shops were sampled for the presence of Salmonella, Campylobacter and Aeromonas species. Eight fish tanks contained unusual serotypes of salmonella. None had been used to house terrapins. One hundred and three isolates of Aeromonas species were obtained from 98 tanks. One tank contained Plesiomonas shigelloides. No Campylobacter species were isolated. It is suggested that a tropical aquarium may constitute an infection hazard.

Cross-reactions of 17 members of the family Legionellaceae were studied by four different serological techniques: immunofluorescence (IF), slide agglutination (SA), microagglutination (MA) and immunodiffusion (ID), using antigens and rabbit antisera prepared in our laboratory. Results obtained corresponded closely with those described by other authors, especially for IF and SA.

The 17 antigens were further tested by IF with a panel of sera previously diagnosed as positive for legionella. A high number of positive reactions with several of the antigens tested were found, half of them being positive for Legionella pneumophila serogroup 1, usually in combination with other serogroups or species. The remaining sera presented a great variety of patterns combining different antigens.

Five laboratories serving a population of 1·5 million participated in a 2-year survey of campylobacter, salmonella and shigella infections in patients suffering from gastrointestinal symptoms. In total, 33857 faecal specimens were examined of which 5·5% yielded campylobacters, 3·4% salmonellas and 0·8% shigellas; incidence of infection (per 100,000 population per year) was 58, 38 and 9 respectively. Peak incidences occurred at different ages for each organism: campylobacter, 1–4 years (183); salmonella, less than 1 year (181); shigella, 1–4 years (17). There was a secondary peak in campylobacter incidence in patients aged 15–24 years (87), which was not seen with salmonella or shigella infections.

By recording the age and sex of all patients submitting faecal specimens, it was shown that sampling rates were disproportionately high in infants aged less than 1 year (12:1 relative to other ages). Thus the percentage of faecal samples positive in infants – in sharp contrast to incidence values – was the lowest of any age group for all three organisms. By taking the numbers of faecal specimens tested as denominators in this way, the highest campylobacter isolation rates were in young adults, with a notable male predominance in the 15–24 year (1·7:1) and 45–54 year (1·6:1) age groups. This male predominance was accentuated during the summer (2·1:1) when incidence was generally high. The maximum percentage isolation recorded by any laboratory was 32·5% in males aged 15–24 years in June.

The reasons for this pattern of campylobacter infection are unknown, but the similarity of the results between laboratories and the regularity of the seasonal fluctuations recorded over the last G years indicate that the sources and routes of infection are geographically similar and stable, yet different from those of salmonellosis.

The usefulness of sodium dodecyl sulphate–polyacrylamide gel electrophoresis patterns of cell envelope proteins for classifying strains of Acinetobacter calcoaceticus was studied using 129 isolates from 16 in-patients in a teaching hospital. In 11 patients, all of the isolates from each patient exhibited the same pattern irrespective of the body site or time of isolation. The patterns of the isolates from four other patients were indistinguishable, with the exception of one isolate per patient. In the isolates from one patient five patterns were observed. In several cases isolates from different patients exhibited the same pattern. The relative frequency of some of these patterns was low. Epidemiological data were compatible with the assumption that the concurrent presence of bacteria of these patterns in the patients was the result of cross-infection. For one pattern, which was seen in seven patients, cross-infection could not be substantiated. On the basis of analysis of electrophoretic patterns in combination with epidemiological data on a number of strains it is concluded that cell-envelope protein profiles appear to be a useful aid in studying the dissemination of Acinetobacter in the hospital environment.

Twenty-nine strains of penicillinase-producing Neisseria gonorrhoeae (PPNG) and 30 non-penicillinase-producing strains, all isolated in the Gambia, were characterized in terms of their plasmid content, auxotype and protein-I serovar. Sixty-two per cent of the PPNG strains contained the 3·2 MDa penicillinasecoding plasmid, and 38% had the 4·4 MDa plasmid. All the PPNG strains contained the 2·6 MDa cryptic plasmid but lacked the 24·4 MDa conjugative plasmid. In contrast, 46·7% of the non-PPNG strains harboured only the cryptic plasmid while 16·7% contained both the cryptic and conjugative plasmids. Seventeen per cent of the non-PPNG strains contained the conjugative plasmid only and 20% lacked plasmids.

The PPNG and non-PPNG strains also differed in terms of their protein-I serovar. Eighty-six per cent of the PPNG strains belonged to serogroup 1A, whereas the majority (60%) of non-PPNG strains belonged to serogroup IB. There was no significant difference in the auxotypes of the PPNG and non-PPNG strains, with both groups consisting predominantly of prototrophic and prolinerequiring strains, with a minority of strains requiring arginine. When the 59 strains were each characterized in terms of their combined plasmid profile, auxotype and serovar, 39 different combinations were noted, which indicates the heterogeneous nature of the gonococcal population found in the Gambia.

A total of 150 patients were treated for tetanus in the tetanus ward of the J. J. Hospital, Bombay, between October 1983 and January 1986. The complications of tetanus and the mode of management in the presence of restricted resources are outlined. Intensive care, proper nutrition, early tracheostomy and ventilator support in severe tetanus were chiefly responsible for an overall reduction in mortality from 30 to 12%. The mortality in severe tetanus was reduced from 70 to 23%.

Sudden death due to unexpected cardiac arrest was an important complication in severe tetanus. We observed that an abrupt marked rise in rectal temperature ( > 107 °F, 41·7 °C), if undetected, could lead to sudden circulatory collapse and death. Well-marked hypoxaemia was observed in all patients with severe tetanus, and was related to ventilation perfusion inequalities and to an increase in the true venous admixture (increased Qs/Qt)in the lungs. Bronchopulmonary infections and the adult respiratory distress syndrome added significantly to morbidity and mortality. Autonomic cardiovascular disturbances included bradycardia alternating with tachycardia, and hypertension which was either labile, paroxysmal or sustained. Persistent hypotension was of ominous significance. Amongst numerous complications involving other systems, sepsis and septic shock were associated with a high mortality.

Specific IgM antibody production in patients with serologically proven Mycoplasma pneumoniae infection by the complement fixation (CF) test was studied using a μ-capture ELISA. Sera from 79% of patients were found to be IgM positive. Patients could be divided into two groups relating to the amount of specific antibody produced. High levels of specific IgM (≥10 units) were more commonly found in younger patients. Seventy-six per cent of patients under the age of 20 produced relatively high levels of IgM compared to 35% of patients over the age of 20. In contrast, the number of patients who produced low or undetectable levels of IgM ( < 10 units) was found to increase with age. This trend was found to be significant which suggests that low or undetectable levels of IgM may be due to reinfection with M. pneumoniae. Specific IgM was found to appear in the serum at approximately 7 days after the onset of symptoms, peaking at between 10 and 30 days, and then falling to undetectable levels at an estimated 12–26 weeks post onset of symptoms. Twenty-eight per cent of acute-phase sera (CF titres < 256) from patients whose sera subsequently showed a fourfold or greater rise in M. pneumoniae CF antibody titre were IgM positive. Thus using μ-capture ELISA a diagnosis of M. pneumoniae infection may often be made more rapidly than by the complement fixation test.

The incidence of hospital-diagnosed human hydatid disease acquired in the UK was estimated from a survey based on Hospital Activity Analysis data for the period 1974–83. The average annual incidence in Wales was 0·4 per 100000 population compared with 0·02 per 100000 in England. Within Wales, Powys, and particularly Brecknock, had the highest incidence (7 per 100000 per year). Compared with the period 1953–62, the average annual incidence for Wales fell by half (from 0·8 to 0·4 per 100000 per year), but in Powys the incidence did not decline, and in Brecknock and Montgomery there was a marginal increase. In comparison with 1953–62, the age-specific incidence in Wales and Powys decreased in each age group with the notable exception of children < 15 years of age. This finding emphasizes that transmission of Echinococcus granulosus to humans is still occurring at hyper-endemic levels in parts of England and Wales and that control efforts should be intensified.

Human immunodeficiency virus antigen (HIV-ag) was determined by enzyme immunoassay (EIA) in HIV-antibody (anti-HIV) positive as well as pre-anti-HIV seroconversion sera and the results analysed according to stage of infection, risk group, age and geographic origin. Eleven (19%) of 58 homosexual men tested showed HIV-ag in a serum taken 3–4 months before or one at the time of anti-HIV seroconversion. In another eight (14%) HIV-ag persisted after seroconversion and half of them developed AIDS or AIDS-related complex (ARC) in contrast to none of the other 50 anti-HIV seroconversions. Two (13%) of 16 haemophiliacs tested had HIV-ag only in the first anti-HIV seropositive sample. HIV-ag was present in 86% (30/35) of Dutch homosexual men with AIDS, in 32% (7/22) of men with ARC and in 17% (24/145) of men with persistent generalized lymphadenopathy (PGL) or without symptoms. Three percent (2/60) of sera of asymptomatic i.v. drug users from Amsterdam were HIV-ag positive. Ten percent (1 of 10) of sera from Central Africans with ‘Slim Disease’ were HIV-ag positive. Among infected children from the USA or Europe 89n100% (8/9 and 2/2) of AIDS cases, 67–100% (6/9 and 3/3) of children with ARC and 75% (3/4) of asymptomatic children were HIV-ag positive. The HIV-ag EIA appears to be able to identify HIV infection earlier than the available anti-HIV assays in a significant number of cases. Since persistence of HIV-ag, except possibly in African cases, is strongly associated with clinical deterioration, HIV-ag appears to be a suitable marker for, independent of their clinical status, selecting individuals for antiviral therapy and also for monitoring the efficiency of such therapy.

Hitherto, detection of lymphoproliferative disease virus (LPDV), a C-type retrovirus of turkeys, has proved difficult since no tissue culture or serological assay has been available. Development of serological tests has been hampered by the problems of raising virus-specific antisera. An indirect enzyme-linked immunosorbent assay (ELISA) is reported, using a viral antiserum raised with bromelain-digested virus.

The assay specifically detected purified virus at a concentration of 250 ng/ml or greater. In an experiment to detect virus in plasma from turkeys over a period of 4 weeks following LPDV infection, ELISA results correlated closely with the viral reverse transcriptase activity. Both assays were of similar sensitivity and detected small amounts of virus in high-speed pellets of turkey plasma. Evidence is presented indicating that LPDV-infected or hyperimmunized turkeys do not produce readily detectable circulating viral antibodies. In reciprocal ELISA tests, using antibodies to group-specific antigens of other avian retrovirus groups (avian sarcoma-leukosis (ASLV) and reticuloendotheliosis (REV)) no antigenic cross-reaction was found between LPDV, ASLV and REV.

Cases of African swine fever (ASF) confirmed in the laboratory in 1985 and 1986 and other data obtained since 1984, in particular an extension of the serological survey of free-ranging domestic pigs undertaken from 1981 to 1984, are presented to give an updated survey of the ASF situation in Malawi and a revised estimate of the ASF enzootic area. Evidence is presented that the area may include some border areas in Dedza and Ntcheu districts and may be expanding in some localities.

Investigations using a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for the measurement of antibodies against foot-and-mouth disease virus (FMDV) in sera from sheep and from cattle are reported, and results compared with those obtained by virus neutralization (VN) tests.

Serum antibody titres in sheep after primary vaccination and in cattle challenged with a natural aerosol after vaccination were similar by ELISA and VN. However, the antibody levels detected in sera of cattle during early infection and of vaccinated cattle after intradermolingual challenge were clearly greater by ELISA than by VN.

The ELISA titres in cattle sera following synthetic peptide vaccination indicated some relationship to protection and were clearly different from those recorded by VN. On the other hand, the antibody levels following conventional vaccination showed that ELISA and VN titres in cattle sera were related to protection. Although there was a good agreement between the ELISA antibody titre and protection for the four vaccines used, by VN the titre which afforded protection varied depending on the vaccine used.

The ELISA was considered therefore to be more reliable than the VN and may prove useful for evaluating the immunological response of animals following infection and following vaccination.

A field strain of influenza A (H3N2) virus isolated in embryonated eggs during the 1984–5 influenza outbreak (A/Finland/13/85E) was compared in an antigenic analysis with virus from the same clinical specimen isolated in MDCK cell cultures (A/Finland/13/85M). The M-virus appeared to be more sensitive to haemagglutination-inhibiting antibodies against heterologous viruses than did the Evirus. The results of propagation and plaque purification experiments support the hypothesis that a single clinical specimen may consist of distinct antigenic variant subpopulations promoted selectively by the host during isolation procedures. Receptor-binding properties are discussed as a possible explanation for this selectivity.

A set of 471 paired sera consisting of pre-epidemic and post-epidemic specimens taken from the same subjects in 1984–5 was studied for haemagglutinationinhibiting antibodies to six influenza A (H3N2) virus strains, including the E-virus and the M-virus from A/Finland/13/85. Of the antigens used, the M-virus detected significant antibody increases more frequently than did the E-virus (10·0 v. 5·9%). The superiority of the M-virus may rest primarily in its ability to pick out anamnestic antibody responses. Irrespective of this cross-reactivity, preepidemic antibody to the M-virus was fairly well associated with protection. In the set of sera (230 specimens) collected in summer 1985 to represent different age groups, the antibody status against the M-virus was significantly better than the status against the E-virus. The results suggest that, at least in some instances, antibody to MDCK-grown virus is a more accurate indicator of the immune status of a community than antibodies to egg-grown virus variants.