Thirty-seven isolates of cytomegalovirus (CMV) were obtained from a group of 20 promiscuous homosexual men, either suffering from the acquired immunodeficiency syndrome (AIDS) at the time of CMV isolation, or who developed AIDS subsequently. The isolates of CMV were characterized by the method of DNA restriction analysis. All epidemiologically unrelated strains of CMV exhibited different fragment migration patterns and no one strain appeared to be associated with AIDS or any particular disease pattern in these patients.

Sequential isolates of CMV were obtained from nine patients in the study group either from different sites at the same time or from the same site on different dates. In the case of seven of the men, viruses with minor differences in restriction profile were obtained, possiblyrepresenting sub-populations of an endogenous strain of CMV. In two of the patients, reinfection with different strains was apparent. We conclude that reinfections with CMV in AIDS patients can occur, but the isolation of strains exhibiting major differences in genome structure seen by restriction enzyme analysis was uncommon.

IgM antibodies specific for cytomegalovirus (CMV) were demonstrated in 15 (2.6%) of 575 umbilical cord sera obtained from newborns in Kuwait. Some 93% and 50% of these CMV-IgM positive cord sera displayed markedly raised (more than normal mean + 2 S.D.) content of total IgM and IgA respectively. In contrast, only 0.2 and 1.8% of the CMV-IgM negative cord sera had elevated total IgM and IgA. respectively. Rheumatoid factor (RF) was demonstrable. at concentrations of 30 IU/ml or more, in 67% of the CMV-IgM positive as compared with 3.2% of the CMV-IgM negative sera whereas interferon alpha was found in the serum of only one of these infants. These results indicate that raised total immunoglobulin. in particular IgM. concentrations and the detection of RF in cord blood are useful non-specific markers for the identification of congenital CMV infection.

Isolates of adenovirus types 1 and 2, obtained from 11 infants with prolonged faecal excretion (up to 515 days), were compared by DNA restriction analysis with seven standard endonucleases which recognize hexanucleotides and two additional endonucleases which recognize tetranucleotides. In all instances identical genome types were identified in isolates obtained early and late after infection. Our interpretation of these data is that a chronic persistent infection occurred in these children. and not a reinfection with the same serotype.

Information was collected on confirmed outbreaks of western equine encephalitis (WEE) in North America east of the Rockies for 1981 and 1983 (epidemic years) and 1980 and 1982 (non-epidemic years). The initial pattern of outbreaks in Manitoba, Minnesota and North Dakota was determined for each year. Backward (and in some instances forward) wind trajectories were computed for each day 4–15 days (incubation period) before the initial outbreaks of WEE in a given area of province or state.

Three hundred and seventy-six patients attending their general practitioner with cutaneous warts at five health centres in Northern Ireland were screened for human papilloma virus (HPV) types 1 and 2 IgM antibody using an indirect immunofluorescence test. Eighty-eight (23·4%) patients were positive for HPV type 1 IgM and 156 (41·5%) for HPV type 2 IgM. HPV 1 IgM antibody was significantly more likely to be associated with plantar warts than warts elsewhere (P 0·0001). HPV 2 IgM was present in 45 (34·1%) patients with plantar warts and 99 (45·6%) patients with warts at other sites (P=0·1). Evidence of multiple infection by HPV types 1 and 2 was demonstrated by the finding of HPV 1 and 2 IgM antibodies in the sera of 16 (4·3%). HPV 4 was found in only 1 out of 30 biopsies and HPV 4 IgM was undetectable in 50 randomly chosen sera.

African swine fever (ASF) has been reported in the Eastern Province of Zambia since 1912 and is now considered to be enzootic there. A survey of the distribution of ASF virus in Zambia was carried out by virus isolation from Ornithodoros moubata ticks collected from animal burrows in National Parks and Game Management Areas in northern, eastern, central and southern Zambia. ASF virus was isolated from ticks in all areas examined. The prevalence of infection in O. moubata was between 0·4% in South Luangwa National Park and 5·1% in Livingstone Game Park and mean infectious virus titres ranged from 103–4 HAD50/tick in Kakumbe Game Management Area to 105·9 HAD50/tick in Chunga and Nalusanga Game Management Areas. The prevalence of infection in adult ticks was between 4·7% and 5·3% in all areas examined except Sumbu National Park and Livingstone Game Park, where the prevalence was 15·1% and 13·2% respectively in adult ticks. The ratio of infected females to males for all the infected adult ticks in all areas of Zambia was 3·2:1.

Examination of sera from 184 children aged between 0 and 12 years and 161 adults revealed a close correlation between age and the level of humoral anti-RS virus immunity. Secretory IgG antibodies were found in children in their first months of life. Evidence for their release into secretions from the serum was obtained. This might explain the positive correlation between serum antibody levels in women recently confined with the morbidity due to RS virus in children during their first months of life. Secretory IgA antibodies were found from 4 months untill old age. The secretions of children and adults contained virus-neutralizing activity which was non-immunoglobulin in nature, as well as antibodies. However, in contrast to secretory antibody this material did not prevent development of severe RS virus infections.

In 1986 and 1987 foot-and-mouth disease virus (FMDV) serotype A was isolated from outbreaks of disease in Saudi Arabia and Iran. Selected virus isolates were antigenically distinct from the prototype A22 virus strain (A22/Iraq/64), but were serologically related to each other. However, polyacrylamide gel electrophoresis showed that whilst the respective Saudi Arabian structural polypeptides were homogeneous, those from an Iran isolate were distinct. Direct sequencing of part of the P-1D (VP1) gene demonstrated considerable difference in nucleotide homology between the two groups of viruses; the Saudi Arabian viruses were closely related to each other but only distantly related to both the A22 prototype virus strain and the Iranian virus isolate. The latter viruses were only slightly more closely related to each other. Thus there appeared to be at least two distinct FMDV type A variants co-circulating in the Middle East, both of which differed considerably from the classical A22 subtype.

An antiglobulin enzyme-linked immunosorbent assay for rubella-specific IgG1 and IgG3 was adapted to measure antibody avidity by incorporating a mild protein denaturant, diethylamine (DEA), into the serum diluent. Sera were tested at varying dilutions, both with and without DEA, if they contained sufficient specific IgG1 or IgG3. The optical density (OD) was measured and curves were plotted. The highest OD (V) was noted and halved (V/2). The distance between the OD curves at V/2 was measured as the DEA shift value.

Sera were examined from people whose sera contained rubella-specific antibodies as a consequence of infection or vaccination in the distant past (24 sera), recent primary rubella (66 sera), symptomatic reinfection (11 sera) or asymptomatic reinfection (64 sera). For specific IgG1 the DEA shift value was <O·6 for cases of rubella in the distant past, compared with >0·8 for the first month after primary infection. The maximum DEA shift value for the sera from cases of reinfection was 0·65.

No serum from cases of rubella in the distant past contained sufficient specific IgG3 to estimate avidity. The sera collected within 1 month of onset of primary rubella gave DEA shift values >O·7 compared with sera from reinfections, which gave DEA shift values <O·6, except for two sera from a case of symptomatic reinfection.

Thus the assessment of specific IgG subclass avidity is of value in differentiating serologically primary rubella from reinfection.

Five rubella antigens were evaluated in an antiglobulin enzyme-linked immunosorbent assay for rubella-specific IgG subclass antibody. One monoclonal anti-human IgG subclass antibody was used for each of IgG1, IgG2 and IgG4, but two were compared for IgG3. A total of 101 sera were tested from cases of rubella in the distant past and from cases of primary rubella, reinfection and following immunization. Only one serum gave a discrepant result for specific IgG1, being positive with only one rubella antigen, a commercially prepared antigen coated on to microtitre wells (Enzygnost; Behringwerke). No sera contained detectable specific IgG2. Only four sera contained specific IgG4, and this was detectable only with Enzygnost antigen. For specific IgG3 little difference was observed between the two monoclonal anti-human IgG3 subclass antibodies; only two very weakly positive sera gave discrepant results. However, varying results were obtained for specific IgG3 with the different antigens. Enzygnost gave more positive results for specific IgG3 with most categories of sera.

It is concluded that the differences between various reports of the rubella-specific IgG subclass profile cannot be explained entirely by the use of different rubella antigens.

A seroepidemiological survey was conducted on subjects who had received a full vaccination course with live attenuated poliovirus 2–16 years before. For strains 1 and 2 prevalence of seropositives and median values dropped gradually during the first 10 years; strain 3 showed a much earlier decline. Environmental displacement of wild poliovirus by the attenuated, less immunogenic strain might eventually induce a ‘gap’, should complacency hamper needed vaccination efforts.

The efficacy of interferon A (rIFN-α2A), an Escherichia coli-derived interferon, in the prophylaxis of acute upper respiratory tract infection, was evaluated in a community-based double-blind placebo-controlled study in the Australian winter of 1985. The trial population of 412 healthy volunteers (190 males and 222 females, aged 18–65 years) self-administered 1·5, 3·0 and 6·0 megaunits (MU) of interferon A per day or a placebo, intranasally for 28 days.

The period of study coincided with an outbreak of H3N2 influenza A (detected in 35 of the 107 acute specimens) as well as substantial numbers of respiratory syncytial virus and adenovirus infections. Rhinoviruses were isolated from only three specimens. In many cases, subjects had laboratory and clinical evidence of having had more than one respiratory tract infection during the period of the study. Viruses were detected in 54 or 107 acute specimens (49%).

No statistically significant differences were noted between the various treatment groups in the incidence of laboratory-proven viral infection (virus isolation and/or antibody response). Analysis of reported symptoms indicated that blood-tinged mucus and nasal stuffiness occurred more frequently with higher doses of interferon. There appeared to be no clinical benefit from the use of interferon A in the amelioration of symptoms.

In-patients at a London hospital over one year from whom the south-east England strain of ‘epidemic’ methicillin-resistant Staphylococcus aureus (MRSA) was isolated were compared with in-patients with strains of methicillin-sensitive Staphylococcus aureus (MSSA). MRSA were virtually entirely hospital-acquired; isolates before 10'days were uncommon and related to recent previous admission. Thereafter first isolates occurred at a fairly constant daily rate of about 1·9 per 1000 in-patients. Acquisition of MSSA after more than 4 days in hospital occurred at a similar constant rate. Such strains were less likely to be penicillin-sensitive than strains isolated in the first 4 days after admission (11 vs. 22%) and were considered to be hospital-acquired. The single MRSA strain caused 40 infections in a year, about half of all hospital-acquired staphylococcal infections. Patients prescribed anti-staphylococcal antibiotics and patients with indwelling cannulae both had about a ninefold increased risk of acquiring MRSA. There was no reciprocal increase in MSSA infections after control measures had substantially reduced the number of MRSA infections.

The inhibitory influence of cyanuric acid on the virucidal effect of chlorine was studied. The time required for 99·9% inactivation of ten enteroviruses and two adenoviruses by 0·5 mg/l free available chlorine at pH 7·0 and 25○C was prolonged approximately 4·8–28·8 times by the addition of 30 mg/l cyanuric acid. Comparative inactivation of poliovirus 1 by free available chlorine with or without cyanuric acid revealed the following. The inactivation rate by 1·5 mg/l free available chlorine with 30 mg/l cyanuric acid or by 0·5 mg/l free available chlorine with 1 mg/1 cyanuric acid was slower than by 0·5 mg/1 free available chlorine alone. Temperature and pH did not affect the inhibitory influence of cyanuric acid on the disinfectant action of chlorine. In the swimming-pool and tap water, cyanuric acid delayed the virucidal effect of chlorine as much as in the ‚clean’ condition of chlorine-buffered distilled water. The available chlorine value should be increased to 1·5 mg/l when cyanuric acid is used in swimming-pool water.

Six patients developed local infection after being bitten or groed by swine. Wounding was often deep and occurred characteristically on the posterior aspect of the thigh. Severity of infection caried from simple wound infection with discharge and slouth to cellulitis and abscess formation; pathogens included haemolytic streptococci, pasteurellae, Bacterodies sp., Proteussp. and Escherichia coli and were usually isolated in mixed culture. A patient with Pasteurella aerogences infection apperars to be the first reported in England. A seventh patient developed Streptococcus milleri septicaemia after wounding himself while cutting teeth from piglets. It is suggested that a course of broad-spectrum antibiotics should be given as part of the initial treatment when patients present with the more servere pig bite injuries.

From January 1983 until December 1985, 35 cases of sporadic nosocomial legionella pneumonia, all caused by Legionella pneumophila, were diagnosed in a university hospital. L. pneumophila serogroup (SG) 1 was cultured from 12 of the 35 cases and compared to corresponding L. pneumophila SG 1 isolates from water outlets in the patients' immediate environment by subtyping with monoclonal antibodies. The corresponding environmental isolates were identical to 9 out of 12 (75%) of those from the cases. However, even in the remaining three cases identical subtypes were found distributed throughout the hospital water supply. From the hospital water supply four different subtypes of L. pneumophila SG 1 were isolated, three of which were implicated in legionella pneumonia. Of 453 water samples taken during the study 298 (65.8%) were positive for legionellae. Species of Legionella other than L. pneumophila have not been isolated. This may explain the exclusiveness of L. pneumophila as the legionella pneumonia-causing agent. Our results suggest that the water supply system was the source of infection.

The prevalence of cardiac morbidity due to Change' disease was assessed in a rural community in Central Bolivia. Sixty-nine of 104 persons (66%) were seropositive to Trypanosoma cruzi by two serological methods. Two of 35 (6%) seronegative individuals presented with modest ECG alterations (left anterior hemiblock), but 21 of 69 (30%) seropositives showed modest and severe abnormalities (6 complete right bundle branch block. 2 polyfocal or frequent extrasystoles, 9 ischaemic ST alterations). A high percentage (56%) of domiciliary Triatoma infestans was infected with T. cruzi. There was a significant association between seropositivity and substandard housing. Priority preventive measures should thus include house improvement (to reduce bug infestation) and health education.

During the 10-year period 1978–87 there were 48 outbreaks of food poisoning in Scottish hospitals affeeting a total of 2287 persons of whom 12 died. This compared with 50 outbreaks during the previous 5 years (1973–77) when over 1500 persons and 7 deaths were recorded. Although the incidence of outbreaks has decreased the average number of persons affected in outbreaks has increased. A marked reduction was seen in the incidence of outbreaks due to Clostridium perfringens, in contrast to foodborne salmonellosis which remains a problem. Thirty-four hospitals, of which 10 reported two or more outbreaks, were involved. The type of hospitals most frequently affected were general (14), psychiatric (13), geriatric (9) and hospitals for the mentally subnormal (7). Meat, including poultry meat, was incriminated in over 90% of outbreaks where a food vehicle was identified. In modern or re-equipped kitchens cooking in advance with subsequent reheating is being progressively discontinued as more food is being cooked on the day of consumption, a practice which may readily explain the decreasing incidence of outbreaks due to Cl. perfringens. Bacterial cross-contamination from poultry-meat and other raw foods, compounded by inadequate temperature control, however, continues to be a problem in some hospitals. It is too early as yet to determine whether the removal of Crown immunity will have any effect on the future incidence of hospital ‘food poisoning’.

Direct and indirect antigen capture enzyme immunoassays (Ag-EIA) have been developed for the detection of Mycoplasma pneumoniae in nasopharyngeal aspirates or sputum from respiratory infection. The sensitivity of the two Ag-EIA were similar, but the indirect method using polyclonal rabbit and guinea-pig antisera was more convenient. The Ag-EIA had a detection limit of 104–4·5 colony-forming units/ml of sample. It was specific for M. pneumoniae and gave a low level response with M. genitalium. There were no cross-reactions with 10 other species of mycoplasmas. Tests with a wide range of bacteria and chlamydia group antigen, representing agents sometimes found in the respiratory tract, were also negative. At the current level of development, the Ag-EIA detected about 90% of specimens that were also positive for culture; 43% of specimens from culture-negative-seropositive patients gave a positive result. The overall pattern of results indicated that while antigen detection is a quick and effective substitute for the slow culture method, serological examination for specific IgM antibody is also necessary to give a complete diagnostic coverage.

The efficiency of the direct detection of Mycoplasma pneumoniae in respiratory exudates by an antigen capture, indirect enzyme immunoassay (Ag-EIA), has been compared with its detection with a cDNA probe (‘Gen-Probe assay’) directed against the specific ribosomal RNA sequences of the organism (‘Mycoplasma pneumoniae Rapid Diagnostic System’, Gen-Probe, San Diego, California).

Both assays showed excellent specificity against a range of mycoplasma species suspended in negative nasopharyngeal aspirates; only M. pneumoniae and M. genitalium reacted. In experiments with graded doses of viable M. pneumoniae cells suspended in negative nasopharyngeal aspirate, the Gen-Probe assay was more sensitive than Ag-EIA; detection limits were respectively 2 × 103 c.f.u./ml (3·2 × 105 genomes) and 2·5 × 104 c.f.u./ml (4 × 106 genomes); detection levels 10–100 times less sensitive than culture.

The two assays were also tested on nasopharyngeal aspirates or sputum specimens from 90 patients with respiratory infection; 67 of these were culture-or seronegative for M. pneumoniae and 23 were culture-or seropositive. Ag-EIA detected 21 (91%) of the latter but the Gen-Probe assay detected only 5 (22%). Both assays were negative with the 67 culture-/sero-negatives; there were no Gen-Probe assay positive/Ag-EIA negatives.

Overall, it is concluded that although Ag-EIA and the Gen-Probe assay are effective substitutes for culture as a diagnostic procedure, there is a significant problem with samples which are culture-negative and from patients who have good serological evidence of current infection. Possible reasons for the disparity between the two assays are advanced.