The prevalence of infections caused by Mycobacterium bovis was estimated in two populations of wild animals in the south west of England. A variety of mammalian species was trapped on farm land where incidents of infection with tuberculosis had occurred in cattle. Bacteriological analysis of lymph node samples and lesions showed that the only animals acting as a reservoir for M. bovis were badgers. Examination of arthropod ectoparasites of infected badgers proved negative for M. bovis and suggests that these are unlikely to act as vectors in transmission of the disease.

An M-antibody capture radioimmunoassay (MACRIA) for anti-rubella IgM was developed. Under optimum conditions positive serum specimens bound up to 20 times as much radioactivity as negative specimens. Positive reactions were expressed in arbitrary units/ml by comparison with a calibration curve derived from results obtained with dilutions of a standard serum.

The specificity of the assay was confirmed by testing IgM and IgG rich fractions of positive sera. One hundred and forty specimens from blood donors, patients whose sera contained rheumatoid factor and patients with acute, non-rubella, virus infections were tested by MACRIA. No significant non-specific reactions were detected.

Paired sera from acute rubella (25 patients) and individual sera from suspected rubella (69 patients) were tested for anti-rubella IgM by MACRIA and by haemagglutination inhibition following sucrose-density-gradient fractionation. There was close agreement between the two methods. The capture assay was more sensitive and could be used to detect the weak IgM response in women given RA 27/3 vaccine. After the natural infection, the MACRIA was strongly positive for two months and remained weakly so for a further two months. Repeat testing of sera demonstrated good reproducibility of the assay.

MACRIA proved a simple, sensitive and specific test for anti-rubella IgM and compared favourably with currently used techniques.

Three different types of bivalent influenza virus vaccine, a whole virus, an aqueous-surface-antigen vaccine and an adsorbed-surface-antigen vaccine were tested at three dosage levels in volunteers primed with respect to only one of the haemagglutinin antigens present in the vaccines.

The local and systemic reactions to all three vaccine types were mild in nature and, following first immunization, the aqueous-surface-antigen vaccine was the least reactogenic. The serum haemagglutination-inhibiting antibody response to the A/Victoria/75 component of the vaccines, to which the volunteer population was primed, was greatest following immunization with the aqueous-surface-antigen vaccine; the greatest antibody response to the A/New Jersey/76 component of the vaccines was observed following immunization with whole virus vaccine.

The specificity of serum anti-HA antibody from children immunized or infected with A/Victoria/75 (H3N2) or A/Texas/77 (H3N2) virus was examined using the single radial haemolysis test together with adsorption of antibody with three antigenic variants A/Hong Kong/68 (H3N2), A/Port Chalmers/73 (H3N2) and A/Victoria/75 (H3N2). The majority of young children reacted to vaccination or infection by producing strain-specific (SS) antibody to the homologous virus. A small proportion of children's sera contained cross-reacting (CR) antibodies capable of reacting with the haemagglutinins of all antigenic variants of the subtype including A/HK/1/68. In contrast, most adults reacted immunologically to either vaccination or infection by producing CR antibody, reacting with all variants of the antigenic subtype including the prototype virus A/HK/1/68 (H3N2).

An epidemiological study and the simultaneous evaluation of anti-Hav antibody using radio immunoassay (RIA) and immunoadherence hemagglutination assay (IAHA) was performed during three hepatitis A epidemics in the Tours area (France). Fifty-seven sera from 35 subjects with viral hepatitis type A and 16 sera from nine children who did not develop any clinical signs of hepatitis were studied. The more explosive epidemic occurred in an institution for mentally retarded children (attack rate 68%). The two major outbreaks observed were due to the introduction in the institutions of individuals infected with hepatitis A virus. Two out of three of the index cases had a seafood dinner three to four weeks before onset of jaundice. Sera taken one week after jaundice were always found to be anti-HAV positive by both RIA and IAHA, and sera taken more than three days before the appearance of jaundice were negative by both methods. Sera taken at the peak of the transaminase elevation were anti-HAV positive by RIA but only one out of two were positive by Iaha. The anti-HAV titre by RIA increased from the time of the appearance of jaundice and the highest titres, over 1/20000 were seen only after several months. Observations of subjects in close contact with patients who seroconverted without any manifestation of hepatitis, confirmed the existence of clinically mute infections.

A relatively simple method for the detection of intra-specific variation of Mycobacterium bovis is described, based on the ability of strains to utilize or remove amino acids from solution. Using the method, 31 strains of M. bovis, isolated from badgers and cattle, have been divided into four major groups with some additional sub-groups and intermediate strains. Preliminary results suggest that the biotypes observed are relatively stable. The method was used in the investigation of an outbreak of bovine tuberculosis in cattle in Gloucestershire where badgers were implicated as a source of infection. The results suggested that transmission of infection had occurred on at least two or three separate occasions. It is suggested that the method could be used in studying the epidemiology of bovine tuberculosis in wild animals, cattle and man.

During 1977 and 1978, 172 samples from 14 batches of domestic meat waste were examined for the presence of salmonellae. Each batch was derived from the domestic refuse collected from approximately 120 houses. Thirty-five strains of ten salmonella serotypes were isolated from 32 samples from 8 batches. The probable origin of these serotypes and their significance when domestic waste is exposed to predation by birds and animals on refuse tips is discussed.

It was observed that small children and pregnant women were affected to only a small extent by the H1N1 influenza outbreak of winter 1978–79. This supports earlier findings from the epidemic season of 1977–78 and demonstrates that the evolutionary changes in the epidemic virus were not reflected in any appreciable way in this curious phenomenon. The frequency of elderly subjects possessing antibodies against the epidemic H1N1 virus was low, and virtually equal in the pre-epidemic and post-epidemic sampling. This low attack rate contrasts with observations on young military servicemen, in whom the re-infection rate was high, thus indicating that the infection with the winter 1977–78 virus had conferred only modest protection against the closely related virus which caused the winter 1978–79 outbreak.

A solid phase M-antibody capture radioimmunoassay (MACRIA) and a serum fractionation method were used to quantitate the IgM response to the hepatitis B core antigen (IgM anti-HBc) in acute and chronic hepatitis B infections.

Antibody to the core antigen was predominantly of the IgM class during theacute phase of hepatitis B. Resolving acute infections remained positive by MACRIA, but at decreasing levels, for as long as 6 months. IgM anti-HBc persisted in HBsAg carriers but at levels very much lower than seen in acute infections. There was no correlation of IgM anti-HBc with severity of chronic liver disease in carriers.

Measurement of IgM anti-HBc by MACRIA enabled accurate identification of acute hepatitis B on single serum specimens.

Serum samples from 14 patients whose burns had become infected with streptococci of groups A (11 patients), C (one patient) or G (two patients), and from 19 burned patients without bacteriological evidence of streptococcal infection were examined for anti-streptococcal antibodies. Tests were made for anti-streptolysin O (ASO), anti-hyaluronidase (AH), anti-deoxyribonuclease B (anti-DNAase B) and antibody against M-associated protein (MAP). Sera from the patients with streptococcal infections were also examined, when this was practicable, for ‘bactericidal’ (anti-M) antibody and for antibody against the opacity factor (OF) of the infecting serotype.

In patients infected with group A streptococci, the ASO response was generally poor, except in patients infected with strains of type T12/M12, and the AH response was rather similar, but most of the patients gave a rapid and vigorous anti-DNAase B response, except when the burn was small or colonization occurred very late. Antibody to the M and MAP antigens, and to OF (when the infecting strain formed this), was weak and transient, or absent, except in three of four patients infected with streptococci of type T12/M12.

Four types of observations have been used to illustrate the seasonal characteristics of epidemic influenza: (1) The experience of a small population during 28 consecutive years, 1946–74, (2) world influenza outbreaks 1964–75 reported to the World Health Organization, (3) the experience of two widely separated localities at about the same latitude, 1969–74, and (4) the experience of two places at latitudes 30° + on opposite sides of the Equator, 1968–74.

The following tendencies are shown. (1) Outbreaks of influenza even in the small community came at approximately the same season almost every year. (2) Outbreaks are globally ubiquitous and epidemic loci move smoothly to and fro across the surface of the earth almost every year in a sinuous curve that runs parallel with the ‘midsummer’ curve of vertical solar radiation, but lags about six months behind it. Such findings exclude the mediation of seasonal control by any agencies of local distribution, and suggest a direct effect of variations in some component of solar radiation on virus or human host. (3) Antigenic variations in influenza A virus tended to have the same seasonal characteristics as epidemicity. This suggests that epidemicity and virus variation are two facets of one seasonally controlled process.

None of these seasonal characteristics can be explained by the current concept of influenzal epidemiology. A new hypothesis recently proposed and recapitulated in the Appendix offers a possible explanation. The primary agency mediating seasonal control remains unidentified.

Strains of Treponema hyodysenteriae capable of inducing swine dysentery in specific pathogen-free pigs were compared with other spirochaetes from the porcine alimentary tract by biochemical and serological tests and by electrophoresis of their proteins. Carbohydrate fermentation and esculin hydrolysis were similar in all the spirochaetes. Indole was produced by T. hyodysenteriae and by some of the other spirochaetes. Analysis of the fatty acids produced from glucose showed a difference between T. hyodysenteriae and other spirochaetes only in the amount of n-butyric acid produced. The indirect fluorescent antibody test showed extensive cross-reactions between all the spirochaetes unless antisera were first absorbed. A microtitre agglutination test and a growth-inhibition test were both more specific; strains of T. hyodysenteriae could be distinguished from the other spirochaetes using unabsorbed sera. Both tests revealed some antigenic heterogeneity among strains of T. hyodysenteriae. The cell proteins of a single strain of T. hyodysenteriae gave an electrophoretic pattern distinct from those of the other spirochaetes.

Two of the six spirochaetes not associated with swine dysentery, PWS/B and PWS/C, were indistinguishable serologically and electrophoretically. The other four strains were serologically distinct from one another and from PWS/B and PWS/C. Only two of these spirochaetes were examined electrophoretically, but each gave a different pattern from PWS/B and PWS/C. The diversity observed among spirochaetes not associated with swine dysentery indicates that their suggested inclusion in a single species, T. innocens, may prove to be unjustified.

The transfer of gentamicin resistance between a coagulase-negative S. hominis strain and various coagulase-positive S. aureus strains on human and murine skin in the absence of a selective agent is described. Transfer occurs at higher frequency on skin than in broth. Skin transfer may account for the apparently explosive occurrence of gentamicin resistant staphylococci in hospitals.

Five different types of liquid soap were studied in hospital wards, each during two months' use. Altogether 1306 finger print samples were taken from the hands of the staff by sampling twice a week and the acceptability of the soaps was measured by a questionnaire. During the use of different soaps only slight differences were found in the numbers of total bacteria or in the occurrence of Staph. aureus and gram-negative bacilli on the hands. During the use of the emulsion-type product studied, several persons who had dermatological problems had lower mean bacterial counts of the fingers than during the use of the other soaps. This soap was also favourably accepted by the staff. After over one year's use of pine oil soap and alcohol, the staff of the hospital was satisfied with the method. However, several persons with skin problems admitted to not using soap or alcohol. The considerable differences found in the acceptability of soaps imply that for use in hospital the choice of a soap acceptable to the nursing staff is important in promoting proper hand hygiene.

Sources of information for monitoring infectious disease are routine data, special surveys and ad hoc investigations. In practice much use is necessarily made of routine notifications and laboratory records although this reporting is often incomplete and may therefore be biased.

In a retrospective study of a 16-year series (up to 1968) of routine records concerning the diagnosis of gastroenteritis at one Public Health Laboratory we found it possible to identify biases. During school outbreaks of dysentery, laboratory investigation of diarrhoea increased appreciably and such response to publicity affects the use of routine data in surveillance. Although the patients examined were probably representative diagnostically, their selection may not have reflected the age incidence of disease. Valid geographical comparisons within the urban area were not feasible because medical practitioners differed in their use of laboratory facilities and in their habits of notification. Nevertheless, as far as can be established retrospectively, these data did reflect time trends in disease incidence and so had value for monitoring purposes.

Several of the biases defined are likely to apply to other sets of routine data. A further communication will describe a statistical method of correcting for quantifiable bias.

Klebsiella of capsular type K2 were investigated to find out whether a single epidemic clone was the source of many outbreaks of infection in different hospitals, in different areas over a period of five years. The klebsiellas studied were found to be very similar; they were of the same biotype, had similar klebecin sensitivity patterns and carried multiple drug-resistance plasmids; however, characterization of these plasmids showed that they were heterogeneous. Thus there was not a single epidemic bacterial clone.

The faecal microflora of breast-fed infants, weaned children and adults has been examined in rural Nigeria and urban U.K. Breast-fed infants had a similar anaerobic flora dominated by bifidobacteria but bacteroides were isolated in less than a quarter of either community. Weaned children in both communities had greater numbers of bacteroides and clostridia than breast-fed infants. Even higher numbers of bacteroides and clostridia were present in U.K. adults but not in Nigerian adults. Numbers of bacteroides and clostridia were greater in a group of Nigerian infants drinking cow's milk than those receiving breast milk alone and lower in a group of weaned children with diarrhoea compared with uninfected subjects.

Routine data used to study infectious diseases may contain biases which obscure trends. A 16-year series (up to 1968) of routine laboratory data was used to study patterns of incidence of infective gastroenteritis for which no laboratory diagnosis could be made. An artificial pattern was detected. This arose because GPs tended to refer a greater proportion of their patients during dysentery epidemics. Multiple regression analysis was used to separate out this effect so that the underlying trends could be observed.

The seasonal pattern of undiagnosed cases showed an autumn peak. There were also early-winter epidemics of disease with little or no excretion of red blood or pus cells in the diagnostic faeces specimen. Some of the winter communicable disease among older children and adults appeared to be associated with signs of a temporary fat malabsorption in pre-school age cases. Undiagnosed cases in older children and adults were not related to the E. coli serotypes causing disease in infants during this period.

The statistical method applied increased the usefulness of these routine data. Although this series of laboratory records is now more than a decade old the results of the analysis can be compared with new observations as more is learned about the epidemiology of previously unrecognized pathogens, especially rota-viruses.

Radioimmunoassay (RIA) tests for anti-hepatitis A virus (HAV) IgM were carried out on 728 sera: 382 were tested by both a method using an anti-μ serum bound to a solid phase and a method involving preliminary separation of IgM by sucrose density gradient (SDG) centrifugation, 354 by the anti-μ method alone and two by the SDG method alone. Similar proportions of sera were found to be positive by each method (42·5%, 41·7%), but equivocal results were commoner by the SDG method (4·7% compared with 1·5%). There were 21 (5·5%) discrepant results from the sera tested by both methods, 20 of which could have been due to the higher sensitivity of the anti-μ method.

The SDG method generally gave unequivocal results on sera collected within six weeks of the onset of jaundice. Separation of the IgM fraction by re-orientation centrifugation was quick, but otherwise offered no special advantage over separation on a swing-out rotor. The use of 2 mercaptoethanol (2 ME) reduction to assess the purity of the IgM fraction increased confidence in the specificity of the test. It led, however, to the exclusion of 16 reactive sera (4·2%), all of which were found to be positive in the anti-μ test.

The anti-μ method gave better discrimination between positive and negative sera than the SDG method and detected IgM both earlier and later in infection. The results of tests designed to check the specificity of the anti-μ procedure were satisfactory. As it is potentially cheaper and easier to perform, the anti-μ method seems, in all respects, to be superior to the SDG method.

Of 1242 samples of seagulls faeces examined, 12·9% were found to contain salmonellae. The number of positive samples was significantly higher (17–21%) near sewage outfalls. Twenty-seven serotypes were isolated, including a new serotype named Salmonella grampian. The range and frequency of serotypes carried by gulls was similar to those in the human population, suggesting sewage as a possible source of gull infection.

The number of salmonellae found in positive samples was low (0·18−191 g−1 faeces). This was similar to the numbers found in sewage, 10−80 l−1, suggesting gulls may only carry infected material without infecting themselves. Antibiotic resistance in the isolates was low, only 21 showing resistance to the antibiotics tested, although most of these were determined by resistance transfer plasmids.