Usage of antibiotics in southern Europe is less well regulated than in northern countries. The proportion (48%) of meningococci in Spain insensitive to penicillin (MIC ≥ 0·1 mg/l) prompted this investigation of antibiotic sensitivities of isolates from Greek patients with meningitis (31) and carriers (47 school-children and 472 recruits). The agar dilution method was used to determine MIC to penicillin G (PN), sulphamethoxazole (SU), rifampicin (RF), cefaclor (CF) and ciprofloxacin (CP).

The proportion of isolates insensitive to PN was 48% for isolates from patients, 19% from school-children and 36·6% from recruits. Resistance to SU (MIC ≥ 16 mg/l) was found in 16% of those from patients, 10·6% from children and 40% from recruits. None of the isolates from patients was resistant to RF (≥ 1 mg/l) but 6% of those from carriers were. Resistance to CF (≥ 4 mg/l) was found in 9·2% of patient isolates, 6·4% from children and 23·7% from recruits. All isolates except one were sensitive to CP (MIC range < 0·0015–0·125 mg/l).

Resistances to PN, SU and RF were analysed by serogroup, serotype and subtype of the bacteria. The proportion of resistant isolates showed some variation between different areas of Greece, but it was not statistically significant.

During 1990, a strain of methicillin-resistant Staphylococcus aureus became epidemic in Spain and spread in a manner analogous to that of EMRSA-1 in England. Isolates of this strain produced little protein A and were resistant to a number of antibiotics including ciprofloxacin. Beta-lactamase production was encoded by a c. 39 kb plasmid, which also conferred resistance to mercury, cadmium, ethidium bromide and propamidine isethionate.

Investigation showed that two variants, separable by supplementary and Fisk phage typing, were circulating. The B variant appeared to spread more readily than the A variant.

The opportunity was taken to compare the discriminatory power of traditional typing methods with molecular techniques. The discriminatory power of the molecular techniques used only reached the same level as the traditional methods when double enzyme digestion of total cellular DNA by EcoR I and Cla I was performed.

An enzyme-linked immunosorbent assay has been used to diagnose serologically the prevalence of Helicobacter pylori infection in Asian life-long vegans. There was no difference in the seropositivity between these individuals and a group of age-and sex-matched Asian meat-eaters, indicating the meat consumption is not a risk factor for H. pylori infection. However, both Asian groups had a higher prevalence of infection than age- and sex-matched Caucasian meat-eaters. Additionally, the Asian individuals had a wider range of specific IgG antibody concentrations than the Caucasians. This did not appear to be due to antigenic cross-reactivity between H. pylori and Campylobacter jejuni. The significance of these observations to the establishment of cut-off levels for the serodiagnosis of certain ethnic groups is discussed.

Sera from ten patients with positive brucella serology were used to investigate antibody cross-reactions between the O-antigens of Escherichia coli 0157 and Yersinia enterocolitica 09. SDS-PAGE profiles of lipopolysaccharide (LPS), purified from strains of E. coli 0157 and Y. enterocolitica 09, were reacted with sera by immunoblotting. All ten sera contained antibodies which bound to the LPS of E. coli 0157, and five of these sera also contained antibodies which bound to the LPS of Y. enterocolitica 09. Absorption studies using these five cross–reacting sera indicated the existence of at least three epitopes exposed on the O–antigens of E. coli 0157 and Y. enterocolitica 09. One antigen binding site appeared to be exposed on the LPS of both organisms, while one epitope was exposed on the LPS of E. coli 0157 only, and another on the LPS of Y. enterocolitica 09 only.

Twenty strains of V. vulnificus isolated from the environment were investigated for characteristics related to their infectivity such as colonial morphology, enzymatic activity and animal assays. The presence of DNase, chitinase, amylase, lecithinase and gelatinase was observed in 100% of the strains, haemolytic activity was absent, and variable results were obtained in elastase, collagenase and chondroitinase. In the animal assays, 70% of the strains were lethal to adult mice, while 45% caused fluid accumulation in suckling mice. Although all strains had opaque colonies, only 3 of the 20 had the three enzymes elastase, collagenase and gelatinase, and only one of these was virulent in animal assays.

One hundred and twenty-eight shigella strains isolated from newborn and infant human faecal specimens at Kaohsiung Medical College Hospital in Taiwan were serogrouped, serotyped and examined for drug-resistance patterns and for the presence of plasmids. Forty-seven pre cent of the isolates were found to belong to the Shigella sonnei serogroup, 41%to the S.flexneri group,9%to the S.boydii group and 3%to the S.dysenteriae group.The serotype with the greatest number of strains was S.sonnei I. (29 %) followed by S. flexneri 1 (27%). Each strain was tested for resistance to 11 antimicrobial agents. Eighty-eight per cent of the strains were resistant to tetracycline, 87% to chloramphenicol, 84% to streptomycin, 52% to ampicillin, 25% to nalidixic acid, 29% to kanamycin, 11 % to cephalothin, 11% to neomycin, 10% to cotrimoxazole, 1% to amikacin and none to gentamicin. The most prevalent resistance pattern was ApCmSmTc (28%). Clinical isolates demonstrating multiple resistance were found to harbour a large transmissible plasmid of 45–75 MDa while isolates without multiple resistance did not. Two large virulence plasmids of 123 and 110 MDa were found in 12 strains of S. flexneri and 4 strains of S. sonnei phase I. Small plasmids of 4·5, 4·2, 3·5, 2·8, 2·5. 2·0 and 1·5 MDa were also present in all strains. These small plasmids were species specific and can be used as marker plasmids to identify species.

Results are presented from a number of epidemiological studies using enzyme immunoassays (EIA) based on the purified anthrax toxin antigens, protective antigen, lethal factor and oedema factor. Studies on sera from a group of 62 human anthrax patients in Turkey and from cattle in Britain following two unrelated outbreaks of anthrax show that EIA using protective antigen can be a useful diagnostic aid and will detect subclinical infections in appropriate circumstances. A serological survey on wildlife in the Etosha National Park, Namibia, where anthrax is endemic, showed that naturally acquired anthrax-specific antibodies are rare in herbivores but common in carnivores; in carnivores, titres appear to reflect the prevalence of anthrax in their ranges. Problems, as yet unresolved, were encountered in studies on sera from pigs following an outbreak of anthrax on a farm in Wales.

Clinical details, including treatment, of the human and one of the bovine outbreaks are summarized and discussed in relation to the serological findings.

Fifteen and five of 20 volunteers challenged with the enterotoxigenic Escherichia coli strain O 78·H11 showed a fourfold titre increase of serum ELISA antibody to the homologous O 78 and the heterologous O 8 lipopolysaccharide antigen, respectively. Sixty-three of 191 sera from 1- to 48-month-old German children showed serum antibody reactive with O 78 antigen, all but two of these O 78-positive sera also showed reactivity with at least one further O antigen. Only 14 of the O 78 reactive sera also showed antibody to heat-labile enterotoxin. In addition, soluble O 8 antigen could inhibit the binding of serum antibody to absorbed O 78 in 68% of the German children. Antibody reactive with O 78 antigen is thus not a reliable serological marker for enterotoxigenic E. coli infection in German children.

Serum samples collected from individuals of a wide range of ages in South Yorkshire between 1969 and 1990 provided the basis for a longitudinal seroprevalence survey of Toxoplasma gondii antibodies. Sera numbering 3868 were screened for T. gondii specific antibodies using a commercial latex agglutination test. The resultant temporal series of serological profiles revealed a rise, with age, in seroprevalence, the rate of which showed a decrease through time. A plateau of around 40–50% prevalence was attained by the 41- to 45-year age-class in 1969 which was not approached until the 66- to 70-year class in the 1988–90 data set. This trend for decline in seroprevalence was confirmed by statistical analysis for the age range 21–60 years. These results may be indicative of a decrease in the rate of toxoplasma exposure in this study community over the 20-year period. The survey of 1988–90 provides a base-line profile of present-day seroprevalence in which 11 % of individuals in the age range 16–45 years (roughly corresponding to the childbearing age-range) show evidence of past infection. The representative nature of the serum collection and public-health implications of these results are discussed.

The relationship between paired hookworm prevalence and mean intensity of infection data from geographically defined communities was examined. The results show that, in spite of major socio-economic and environmental differences between communities, the relationship is consistent and non-linear. A generalized value of k (the exponent of the negative binomial distribution) for hookworms was estimated to be 0.34, which is consonant with previous estimates from cross-sectional data. Maximum likelihood analysis indicates that the severity of hookworm aggregation in humans has an inverse relationship to mean worm burden which is less marked than for Ascaris lumbricoides. A simple model, based on published estimates of hookworm burdens associated with hookworm anaemia, was used to predict prevalence of morbidity from prevalence of infection data for Tanzania, Kenya and Zambia. Predictions correspond to the observation that hookworm anaemia is highly focal, and largely coastal, in distribution. These analyses suggest that locality-targeting of chemotherapy is particularly appropriate for the control of hookworm morbidity.

A total of 121 uropathogenic Pseudomonas aeruginosa strains were examined for production of several virulence-related factors. These strains were distributed in five predominant O-serotypes, i.e. O 4, O 12, O 11, O 6 and O 5, which accounted respectively for 23·9, 23·1, 12·3, 8·2 and 5·7% of isolates. Pyochelin and pyoverdin siderophores were produced by most of the isolates, defective variants occurring at very low frequency (2·4% for pyochelin and 7·4% for pyoverdin). Adherence to uroepithelial cells and production of cytotoxins was demonstrated in 52·8 and 67·7% of the strains, respectively, with higher frequencies for epidemiologically related strains belonging to serotypes O 4 and O 12. Titration of total proteases, elastase and phospholipase C revealed a high degree of heterogeneity among isolates. However, examination of individual O-serotypes by exoenzyme production showed that elevated levels of total proteases and elastase were characteristics of serotypes of minor numerical importance, i.e. O 1, O 10, O 11 and O 17, whilst low levels of elastase were produced by strains belonging to the predominant serotypes, namely O 4 and O 12. Moreover, epidemiologically related strains belonging to serotypes O 4 and O 12 appeared more homogeneous than the whole serogroup, when compared with other groups on the basis of exoenzyme levels.

An Integrated Vector Management (IVM) strategy was implemented from 1981 to 1985 in one part of Pondicherry, South India, for the control of the bancroftian filariasis vector Culex quinquefasciatus (the IVM area). The rest of the town (the comparison area) received the conventional larvicidal input. After 1985 both the areas were managed conventionally. The switch to conventional strategy resulted in an increase of vector density in both areas. The microfilaraemia prevalence in humans showed a general decline (P < 0·05) from 1986 to 1989 only in the IVM area whereas its intensity did not change significantly in either area. While the age-specific rate of gain of infection was generally unchanged in the IVM area, an increase in all age classes was observed after 1985 in the comparison area, where the Annual Transmission Index was high during the previous years. In both areas the rate of loss of infection increased during 1986–9 compared to 1981–6. The results suggest that 3 years is too short a period to relate the changes in entomological parameters to those in the microfilaraemia status of the population.

Oesophagus samples from 714 cattle from Western Australia were examined by artificial digestion to detect the presence of Sarcocystis spp. The overall prevalence of infection was 52%. The prevalence of infection increased with age and was highest in the entire males (92%). The prevalence was lower in cattle which originated from arid and semiarid regions (9 and 31% respectively) than those from tropical (87%) and temperate (60%) regions. possible reasons for these differences are discussed and it is concluded that environmental and management factors as well as host age and sex influence the prevalence of infection with Sarcocystis spp. in cattle.

Herpes-zoster is caused by the reactivation of varicella–zoster virus (VZV). In this paper different hypotheses of how this re-emergence of virus comes about are reviewed and discussed. From these hypotheses, and epidemiological data describing the initial transmission of the virus, a mathematical model of primary disease (varicella) and reactivated disease (zoster) in developed countries is derived. The steady-state age distributions of zoster cases predicted by this model are compared with the observed distribution, derived from a review and analysis of published epidemiological data. The model allows differentiation between published hypotheses in which age of host may or may not influence the probability of viral reactivation. The results indicate that the probability of reactivation must increase with age to allow the observed pattern of zoster cases. The basic mathematical model presented provides a conceptual framework, which may be extended to assess possible control programmes.

Since its development in 1988, a serologic typing scheme for Xanthomonas maltophilia, based on 31 O antigens, has been successfully used to serotype isolates involved in nosocomial outbreaks in the United States. To determine if this serotyping scheme would be useful in typing X. maltophilia isolates from worldwide sources, we obtained additional isolates from 10 countries; of 900 isolates tested, 795 (88·3%) were typable. In order of predominance, the three most common serotypes were 10, 3 and 19. These three serotypes were most frequently associated with respiratory and blood isolates. This serotyping system is useful as an epidemiologic screening method for universal typing of outbreaks of X. maltophilia infections.

The inner membrane of the air cell of hens' eggs was inoculated with Pseudomonas putida, Staphylococcus xylosus, Enterococcus faecalis, Escherichia coli and Salmonella enteitidis.The first mentioned eventually dominated the contamination of the albumen of eggs stored at 4, 15, and 20 °C. The last mentioned did so in eggs stored at 37 °C. The interval between inoculation of the membrane and gross contamination of the albumen was markedly influenced by site of contamination relative to yolk movement.

Unwoven cloth coated with 32 mg/g of a copolymer of N-benzyl-4-vinyl-pyridinium chloride and styrene was found to be effective in removing micro-organisms from water. In experiments demonstrating removal of Escherichia coli by filtration through ten sheets of the unwoven cloth, the rate of removal was 99·99% at a filtration rate of 2·6 cm/h, and remained at 99% even at a high filtration rate of 300 cm/h and a low influent concentration of the bacterial cells such as 10 cells/ml. The rate of removal tended to increase with a decrease in the influent bacterial concentration. Seven other bacteria and two yeasts were effectively removed by filtration through the unwoven cloth. Filtration through the unwoven cloth was also effective in removing spores of fungi from water but was not very effective in removing bacteriophage T4 from aqueous solution.

In order to investigate risk factors for the acquisition of trachoma, and to study the effect of continued exposure to ocular chlamydial infection on the severity of inflammatory trachoma and its cicatricial sequelae, a longitudinal study was conducted in a Gambian village. Over a 20-month period, the incidence of active (inflammatory) trachoma was significantly higher among those sharing a bedroom with an active case (64/561, 11·4%) than among those who were not exposed in this way (37/658, 5·6%) (relative risk 1·97, 95% confidence interval 1·33–2.90). There was a positive trend in the odds ratio for severe to moderate inflammatory disease versus mild disease as the number of active cases in the bedroom increased, but this failed to achieve statistical significance (P = 0·0506). Individuals with inflammatory trachoma of moderate or severe intensity at one survey were significantly more likely than others to have moderate or severe inflammatory changes at a previous or subsequent survey (odds ratio 14·9, 95% confidence interval 3·9–68·0), implying that host factors may be more important determinants of severity than the frequency of exposure to reinfection.

This paper uses mathematical models and data analysis to examine the epidemiological implications of possible immunologically mediated links between patterns of varicella and herpes-zoster incidence in human communities. A review of previously published reports does not clarify whether or not there is a relationship between the incidence of varicella and the incidence of zoster. However, new analysis of data collected by the Royal College of General Practitioners provides indirect evidence for the hypothesis that a high intensity of varicella transmission suppresses viral reactivation. The significance of this finding for proposed varicella vaccination campaigns is explored by a review of published data on the use of the vaccine. No significant difference is shown to exist between the risk of zoster caused by the vaccine and the wild virus. A mathematical model is then developed to take into consideration the influence of the prevalence of varicella on viral reactivation and the impact of vaccination with attenuated virus, which may be able to recrudesce. Under some conditions, mass application of such vaccines may have the impact of increasing zoster incidence. The results presented here indicate that, before starting any vaccination programme against varicella, its consequences need to be assessed in much more depth.

Eight strains of influenza C virus isolated in various areas of Japan between January 1985 and January 1989 were compared using monoclonal antibodies to the haemagglutinin-esterase (HE) glycoproteins and by oligonucleotide mapping of total vRNA. Five of six strains isolated during 1986–9 were closely related to one another and also resembled the virus, C/Aichi/1/81, isolated in 1981 in Aichi prefecture. This suggests that the C/Aichi/l/81-related viruses had an epidemiological advantage over any co-circulating viruses at least during that period. One of two 1985 isolates (C/Nara/1/85) was antigenically indistinguishable from the C/Mississippi/1/80 strain though their oligonucleotide patterns were markedly different from each other. This raises the possibility that C/Nara/1/85 may be a recombinant virus which receives its HE gene from the C/Mississippi/l/80-related parent.