A three-part epidemiological investigation was made on flaviviruses:

1. As a preliminary to tests on cattle sera from the field, the antigenic cross-reactivity of Wesselsbron, Spondweni, Usutu, Banzi, West Nile and yellow fever flaviviruses was studied in antisera prepared in guinea pigs. As described earlier for flaviviruses, sera were found to be highly cross-reactive in haemagglutination-inhibition (HAI) tests, less cross-reactive in complement-fixation (CF) tests and were virtually monospecific in microneutralization (NT) tests in Vero cell cultures.

2. Infection with Wesselsbron (WSL) virus produced mild febrile illness and viraemia in 5 out of 6 newborn calves, 3 out of 4 pregnant heifers and 3 out of 4 ewes. One heifer produced a weak calf which died soon after birth with WSL antibodies in its serum, indicating that infection had occurred in utero. The 3 other heifers produced healthy calves which lacked antibody in pre-colostral serum. Pathological changes occurred in the foetus in 2 out of 3 pregnant ewes and the ewe produced a healthy lamb which had antibodies to WSL virus in pre-colostral serum.

Unlike the situation in guinea pigs, cattle sera were monospecific for WSL virus in CF tests, but sheep sera cross-reacted with Banzi and yellow fever viruses. Re-infection of the cattle with Banzi, West Nile, Spondweni and Usutu viruses failed to induce marked antibody responses. The results suggest that antibodies to WSL virus in cattle sera from the field can be distinguished from those induced by other flaviviruses by quantitative serologial tests.

3. HAI antibodies to WSL virus were detected in 2648/14395 cattle sera tested over 11 years from 1967 to 1978 in the course of investigation of abortion, infertility and other diseases. Results of quantitative HAI, CF and NT tests with six flaviviruses on 409 selected sera confirmed that infection was due to WSL virus. Serological evidence failed to implicate WSL virus as a cause of abortion in cattle. In a prospective study, abortion occurred in only one out of 21 heifers observed to gain WSL infection during pregnancy in the field, but abortion also occurred in five out of 207 heifers which did not become infected with WSL. No histopathological lesions diagnostic of WSL disease were observed in 1998 specimens from cattle, sheep and goats examined over 44 months prior to October 1972, and WSL virus was isolated once, from the organs of a cow, out of 2106 specimens from cattle sheep and goats tested virologically over six years from October 1972 to September 1978. HAI antibodies to WSL virus were detected in one out of 374 sera from aborted cattle foetuses. It was concluded that WSL virus is not an important cause of disease in cattle, despite widespread occurrence of infection.

Sera from 1661 persons in 12 age groups from 0 to 79 years were titrated for toxoplasma antibodies in the indirect immunofluorescence test. The sera were collected from patients with symptoms suggestive of acute, mainly respiratory, viral infections. After the first year of life, the prevalence of antibodies started to rise, reaching 59% between 40 and 79 years of age. From the prevalence of antibodies in different age groups the annual infection risk, i. e. the risk of a non-immune person acquiring toxoplasma infection, was estimated for successive age periods. The estimated annual infection risk increased from 0·5% in early childhood to 3% during adolescence and early adult life.

Approximately 70–80% of females entered the age of reproduction without evidence of seroimmunity to toxoplasma. The risk of primary infection during pregnancy was estimated from the age distribution of parturient women in The Netherlands in 1975 and the age-specific incidence of primary infections, i.e. the incidence in the total population of susceptible and immune persons. This incidence of primary infection decreased from 1·62% per 9 months at the age of 17½–20 years to 0·37% at the age of 35–45 years. The incidence of primary infections in pregnant women was estimated to be 1·25%.

In a Dutch population group neutralizing antibodies against mumps virus were determined by a plaque reduction technique, which proved reproducible, sensitive and specific. The results with sera of about 800 suburban children show that mumps is acquired at an early age with peak acquisition rates between the ages of four and six years. Over 90% have acquired mumps before the age of 14 years. More than 95% of about 1000 adults (18–05 years) have neutralizing antibodies. The relatively constant median titre suggests that antibodies persist during life.

During a family study 77 clinical and 18 subclinical cases were observed. In families with index cases the attack rate was 26/37 = 0·71. Eleven children (excluding six babies) esćaped infection. The mean attack rate during the epidemic was 0·30. The mean titre of mumps neutralizing antibody is maximal during the first year after the disease but declines during childhood. Mothers exposed to mumps in the family occasionally showed a significant rise in titre. Some seronegative mothers remained seronegative after exposure.

In a multi-laboratory trial, minerals-modified glutamate medium (MMGM) was compared with lauryl tryptose lactose broth (LTLB) in the multiple tube method for the enumeration of coliform organisms, including Escherichia coli, in water. Samples of raw and chlorinated waters yielded a total of 2313 positive tube-reactions with MMGM and 2174 with LTLB. These were interpreted either as E. coli; other coliform organisms; or as false positive reactions. The results at first reading (18 or 24 h) and at 48 h have been analysed statistically in terms of (i) most probable numbers of coliform organisms; (ii) positive reactions and their interpretation; and (iii) whether or not the sample yielded any E. coli or other coliform organisms. All three analyses indicated the same trends. For the detection of E. coli in raw waters LTLB was better than MMGM at 18–24 h, but MMGM was better at 48 h with waters containing small numbers of coliform organisms; for raw waters with greater numbers of organisms, both media performed equally well. Analysis of a subset of samples read at both 18 and 24 h indicated that the superiority of LTLB over MMGM with raw waters disappeared by 24 h. For chlorinated waters, LTLB yielded more positive gas reactions at 18–24 h, but fewer of these were E. coli than with MMGM; at 48 h MMGM was clearly better than LTLB for total coliform organisms including E. coli – especially if the numbers were small. MMGM therefore remains the medium of choice for the detection of E. coli as an indicator of faecal contamination of chlorinated drinking water supplies. It is also better for the detection of small numbers of E. coli in other waters.

Malignant catarrhal fever (MCF) herpesvirus was isolated from the nasal secretions of 4/11 young wildebeest calves. In two cases virus was demonstrated in filtered secretions. The presence of cell-free MCF virus would suggest that the virus can be transferred from wildebeest to wildebeest and into cattle in nasal secretions.

In a multi-laboratory trial, lauryl tryptose mannitol broth (LTMB) and minerals-modified glutamate medium with added tryptophan (MMGM + T) were compared as single tube tests for the confirmation of Escherichia coli in water; the confirmed results were also compared with the production of gas from minerals-modified glutamate medium without added tryptophan (MMGM). LTMB and MMGM + T gave similar gas and indole results with about 90% of the water samples in most of the laboratories. When compared with the ‘correct’ results as judged by acid and gas production from lactose peptone water and indole from tryptone water, the difference in the rate of false positive reactions between LTMB and MMGM + T was insignificant; but LTMB gave a significantly lower rate of false negative reactions than MMGM + T. Gas production from MMGM without added tryptophan gave significantly higher rates of both false positive and false negative reactions. Lauryl sulphate is therefore a suitable inhibitory surfactant for use in single tubemedia for the confirmation of E. coli, which can be recommended.

In a multi-laboratory trial with the mombrane filtration technique, three surfactants – Teepol 610 (T610), Tergitol 7 (T7) and sodium lauryl sulphate (LS) – were compared in media for the enumeration of coliform organisms and Escherichia coli in water. A total of 170 samples of water (87 raw and 92 marginally chlorinated) were examined for colony counts of coliform organisms, and 185 water samples (94 raw and 91 marginally chlorinated) for E. coli. Slight differences in the confirmed colony counts between the three media were noted, but few of these were observed consistently in every laboratory. In most laboratories, T7 gave slightly higher counts of E. coli than LS with chlorinated waters; a higher incidence of false-positive results for E. coli at 44 °C was also noted with T7. As there were no outstanding differences in the trial, sodium lauryl sulphate, which is chemically defined, cheap and readily available, is therefore recommended for use at a concentration of 0·1% instead of Teepol 610 in the standard medium for the enumeration of coliform organisms and E. coli in water by the membrane filtration technique.

During an outbreak of food poisoning at a church camp, 16 of the 25 people attending were affected. Despite a thorough search for a bacterial pathogen none was identified. An examination of the Escherichia coli serotypes present suggest that E. coli 0159.H9 may have been the organism causing the outbreak.

In two groups, each containing 56 Pasteurella multocida strains of avian origin, the percentage of multicin-producing strains was 80·4 and 71·4. In two groups containing 46 and 58 isolates tested for sensitivity to multicins, 82·6% and 62·1% respectively were listed as indicators. P. multocida strains producing bacteriocins were active on a range of 1–33 indicators. A preliminary multicin typing system was set up with the use of eight selected indicators; 52% of multicin-producing strains acted on one indicator only. P. multocida serotypes and serologically un-typable strains were subdivided into multicin types.

In 1972 more than 20% of boys admitted to a closed community (Junior Detention Centre) developed acute tonsillitis and group-A streptococci were isolated from more than 40% of all boys at some time during their stay of two months. The most common serotype was M-type 5, which has frequently been associated with rheumatic fever in other epidemics; four cases of rheumatic fever occurred between 1972 and 1977. Various methods were tried to eliminate the infection, but only full penicillin prophylaxis (0·25 g oral penicillin 4 times a day for 10 days) to all boys on entry appeared to be effective.

In a sample of cases of acute tonsillitis, group-A haemolytic streptococci were isolated from 31·7% by the use of dry swabs or unenriched transport medium, but with enrichment medium duplicate swabs, 77·0% yielded positive results. We question the current practice in some laboratories of reporting positive cultures only when more than ten colonies of β-haemolytic streptococci are present. In this survey viruses did not appear to be an important cause of acute tonsillitis.

High titres of streptococcal antibodies (antistreptolysin O, anti-desoxyribonuclease B and anti-M associated protein) were found, not only in cases and carriers, but in boys on entry to the centre. This supports epidemiological evidence that adolescent boys on entry to the centre. This supports epidemiological evidence that adolescent boys are particularly prone to streptococcal throat infections.

The effectiveness of various hand washing and disinfection methods in removing transient skin bacteria was studied in hospital after dry or moist contamination of the hands when nursing burn patients. The results were compared with those of laboratory tests with volunteers. A fairly good correlation of the bacterial reductions existed between hospital and laboratory tests. All other methods removed Slaph. aureus from the hands more effectively than liquid soap. Gram-negative bacilli were more easily removed than staphylococci, even with soap wash alone.

In hospital, none of the washing and disinfection methods always removed all patient-borne bacteria from the hands. After dry or moist contamination and subsequent washing with soap only, colonies of Staph. aureus were often detected in finger-print samples. Staphylococci wero more often completely removed by a 4% chlorhexidine detergent scrub and alcoholic solutions (either with or without previous soap wash) than by liquid soap, hexachlorophene or iodophor preparations. Gram-negative bacilli were more easily removed by all the washing and disinfection methods. After moist contamination, Gram-negative bacilli were more often completely removed from the hands by ethanol than by other treatments.

The results of the present study emphasize the importance of always using gloves when nursing a profuse spreader of bacteria or one who must be protected from infection.

Over a four-year period 878 samples of faeces were collected from five species of small wild rodents and two species of shrews at sites in England, Scotland and Wales. A search was made for Salmonella in these samples but no isolations of this genus were made. Several other genera of Enterobacteriaceae were identified.

The spread of insect-borne animal virus diseases is influenced by a number of factors. Hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. As parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on winds associated with the movements of the Intertropical Convergence Zone (ITCZ) and warm winds to the north and south of the limits of the ITCZ. The virus is often transmitted from a local cycle to a migratory cycle and back again.

Examples of insect-borne virus diseases and their spread are analysed. Japanese, Murray Valley, Western equine, Eastern equine and St Louis encephalitis represent viruses transmitted by mosquito–bird or pig cycles.

The areas experiencing infection with these viruses can be divided into a number of zones: A, B, C, D, E and F. In zone A there is a continuous cycle of virus in host and vector throughout the year; in zone B, there is an upsurge in the cycle during the wet season, but the cycle continues during the dry season; there is movement of infected vectors between and within zones A and B on the ITCZ and the virus is introduced to zone C by infected vectors on warm winds; persistence may occur in zone C if conditions are right. In zone D, virus is introduced each year by infected vectors on warm winds and the arrival of the virus coincides with the presence of susceptible nestling birds and susceptible piglets. The disappearance of virus occurs at the time when migrating mosquitoes and birds are returning to warmer climates. The virus is introduced to zone E only on occasions every 5–10 years when conditions are suitable. Infected hosts introduced to zone F do not lead to circulation of virus, since the climate is unsuitable for vectors. Zones A, B and C correspond to endemic and zones D and E to epidemic conditions.

Similar zones can be recognized for African horse sickness, bluetongue, Ibaraki disease and bovine ephemeral fever – examples of diseases transmitted in a midge-mammal cycle. In zones A and B viruses are transported by infected midges carried on the wind in association with the movement of ITCZ and undergo cycles in young animals. In these zones and in zone C there is a continual movement of midges on the warm wind between one area and another, colonizing new sites or reinforcing populations of midges already present. Virus is introduced at times into fringe areas (zones D and E) and, as there is little resistance in the host, gives rise to clinical signs of disease. In some areas there is persistence during adverse conditions; in others, the virus is carried back to the endemic zones by infected midges or vectors.

Examples of viruses maintained in a mosquito/biting fly–mammal cycle are Venezuelan equine encephalitis and vesicular stomatitis. These viruses enter a migratory cycle from a local cycle and the vectors in the migratory cycle are carried over long distances on the wind. Further examples of virus spread by movement of vectors include West Nile, Rift Valley fever, yellow fever, epizootic haemorrhagic disease of deer and Akabane viruses.

In devising means of control it is essential to decide the relationship of host, vector and virus and the nature of the zone in which the area to be controlled lies. Because of the continual risk of reintroduction of infected vectors, it is preferable to protect the host by dipping, spraying or by vaccination rather than attempting to eliminate the local population of insects.

Pharyngeal micro-organisms of 131 Australian and Malaysian children and adults were compared by analysis of aerobic culture of throat swab specimens. Enteric Gram-negative bacilli were commonly isolated in small numbers from Malaysian adults whether they had sore throats (28%) or not (36%), but were detected in only 9% of Australian adults without sore throats and in only 12% and 4% of Malaysian children with and without sore throats respectively. In other respects microbiological findings were similar in the different groups of subjects studied.

It is concluded that the pharyngeal carriage rate of enteric Gram-negative bacilli may differ substantially between different groups of normal individuals. Our findings also suggest that these micro-organisms do not have a pathogenic role in pharyngitis.

The properties of an atypical Brucella strain isolated from lymph node tissue of a cow slaughtered as a brucellosis reactor were examined. The organism was Gram negative and highly pleomorphic, existing as cocci, coccobacilli, rods, branched and irregular forms which stained with fluorescent antibody conjugates prepared against rough and smooth Brucella abortus strains. It produced lecithinase and required at least 15% v/v equine or bovine serum for growth. It did not need supplementary CO2 for growth, produced H2S and was inhibited by brucella dyes and partially by i-erythritol. Growth inhibition or lysis was produced by brucellaphages. The organism was not pathogenic for guinea-pigs or mice but evoked antibodies mainly to rough Brucella antigens.

Bacteriostatic activity was measured in 244 specimens of milk collected during 1977 throughout lactation of up to one year from 78 mothers; the activity varied from very good to fair and only seven were inactive. There was a wider range of activity than was found previously in milk from English mothers. Activity usually fell slowly during lactation but some of the Gambian mothers produced milk of very high activity, like that of colostrum into the second week of lactation, and two mothers did so at six and nine months; other mothers produced good-activity milk throughout lactation. The bacteriostatic activity varied little with the season but slight decreases from that expectcd were found after the high incidence of infant diarrhoea towards the end of the rainy season.

The bacteriostatic activity of most of the milk tested could be prevented by iron salts but that of colostrum and some of the milks with high activity could not. Only these highly active colostra and milks were inhibitory in vitro when the inoculum was increased from 104 to 106 organisms per ml. These and less active milks were able to inhibit the smaller, standard inoculum for longer than 3 h with the addition of bicarbonate and extra iron-binding protein at the concentrations likely to be present in vivo. Both commensal and pathogenic E. coli were inhibited to a similar degree by these milks and there was no evidence of serotype specificity.

Minced (ground) beef from three supermarkets, three intermediate-sized chain butchers and three small family butchers in each of three geographical areas was examined three times in warm weather and three times in cool. The total viable count (37 and 20°C), numbers of Enterobacteriaceae (37 and 17°C), and presumptive coliforms did not differ significantly between shop type or season. Statistically significant differences in numbers of faecal Streptococci, Staphylococcus aureus and Clostridium perfringens were too small to be of commercial importance, or diagnostic value.

Growth rates of a mixture of Salmonella serotypes inoculated on beef from a commercial abattoir were measured at chill temperatures. The minimum recorded mean generation times were 8·1 h at 10 °C; 5·2 h at 12·5 °C and 2·9 h at 15 °C. Growth did not occur at 7–8 °C. From these data the maximum extent of growth of Salmonella during storage of meat for different times at chill temperatures was calculated. Criteria for deciding safe handling temperatures for meat are discussed. Maintaining an internal temperature below 10 °C during the boning operation would be sufficient to safeguard public health requirements.

A staphylococcal disperser employed as a theatre technician appeared to have been the source of 11 cases of wound sepsis over a period of about 3 years. He was primarily a nasal carrier and after attempts to eradicate Staphylococcus aureus from his nose failed, his skin dispersal was controlled by daily washing with 4% chlorhexidine detergent (‘Hibiscrub’) and he was allowed to resume his theatre duties under careful bacteriological surveillance. Over the following 2 years 173 dispersal tests showed a mean dispersal of 1·7 c.f.u. per 2800 I air compared with a mean of 152 c.f.u. per 2800 I air in the month immediately preceding treatment and 55 c.f.u. per 2800 I in the period after cessation of treatment. One case of wound sepsis was attributed to the technician during the 2 years in which he received skin disinfection treatment.