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Objectives: We studied the prevalence and incidence of hepatitis C virus (HCV) infection in the ongoing Omega Cohort Study of men who have sex with men (MSM)., Methods: From January to September 2001, consenting men (n = 1085) attending a follow-up visit to the ongoing Omega Cohort Study were tested for HCV. If the test results were positive for HCV, we compared them with test results from previous serum samples collected from the time of entry into the original cohort study to determine the time of infection., Results: HCV prevalence at entry was 2.9% and was strongly associated with injection drug use (32.9% vs 0.3%, P<.0001). Only 1 seroconversion was identified in 2653 person-years of follow-up (incidence rate = 0.038 per 100 person-years). The seroconverter was an active injection drug user who reported needle sharing., Conclusions: Sexual transmission of HCV among MSM appears to be rare.

Background: The syndromic diagnostic approach is the most realistic and cost-effective strategy for controlling sexually transmitted infections (STIs) in the developing world. Its potential advantages should be evaluated., Goal: The goal of the current study was to examine whether the syndromic approach might diagnose more cases of cervicitis due to Neisseria gonorrhoeae or Chlamydia trachomatis than laboratory tests., Study Design: The participants were 481 female sex workers in Benin, screened for STIs and treated on the basis of the clinical findings. They were asked to return to the clinic within 10 days for laboratory test results and appropriate treatment when necessary., Results: The prevalence of cervical infections was 24.5%. In comparison to the gold standard, the sensitivity of the syndromic diagnosis approach for the detection of N gonorrhoeae/C trachomatis infections was 48.3%; that of the locally performed laboratory tests was 74.6%. However, the sensitivity of the laboratory tests dropped to 28.8% when it was taken into consideration that 57.6% of the infected women did not return to the clinic within 10 days., Conclusions: The syndromic diagnosis approach should continue to be used for female sex workers in Benin because returning for treatment is problematic. Presumptive treatment at their initial visit could be a complement to this approach, given the high prevalence of cervicitis in this population.

Background: Within an ongoing HIV/STD prevention project aimed at female sex workers (FSW) in Cotonou, Benin, we evaluated time trends in HIV and STD prevalences from 1993 to 1999., Design: Three serial cross-sectional surveys were conducted in 1993 (n = 374), 1995-1996 (n = 365), and 1998-1999 (n = 591). A questionnaire was administered to the FSW and they were screened for HIV, syphilis, Neisseria gonorrhoeae, and Chlamydia trachomatis., Results: The mean percentage of condom use with clients in the week preceding the interview increased from 62.2% in 1993 to 80.7% in 1998-1999 (P = 0.0001). The prevalence of all infections decreased significantly (all P < 0.02; chi-square for trend) over time: HIV from 53.3% in 1993 to 40.6% in 1998-1999; syphilis from 8.9 to 1.5%; gonorrhoea from 43.2 to 20.5%; and chlamydia from 9.4 to 5.1%. However, the mean age of FSW decreased from 31.0 to 28.4 years between 1993 and 1998-1999. Moreover, the country of origin of these women changed dramatically over time: the proportion of Ghanaian women decreased from 66.3% in 1993 to 21.6% in 1998-1999 when the predominant group became Nigerian (38.0%). When controlling for age and country of origin, HIV prevalence was stable over time (P = 0.71), whereas the downward trend remained significant for syphilis and gonorrhoea (both P < 0.001), and was present but not significant for chlamydia (P = 0.13)., Conclusion: These data suggest that the time trends in HIV and STD prevalences are partly due to the changing sex work milieu, but that the intervention also had an impact. Prevention programmes aimed at FSW should be highly prioritized.

Background: Despite a relatively recent decline in the global incidence of Chlamydia trachomatis and Neisseria gonorrhoeae it seems that some segments of the population such as street youth, sex workers, and individuals with social problems or delinquent behavior could be part of a core group for STDs. These persons may be reluctant to undergo STD diagnosis in traditional medical settings., Goals: To determine the prevalence of C trachomatis and N gonorrhoeae infection using polymerase chain reaction on urine samples among subjects attending an anonymous HIV testing clinic and four community organizations in Quebec City, and to identify associated risk factors., Study Design: A cross-sectional study of 626 street youth, sex workers, and women with social problems or delinquent behavior was conducted., Results: The prevalences of N gonorrhoeae and C trachomatis were, respectively, 1.1% (95% CI, 0.5%--2.3%) and 5.8% (95% CI, 4.1%--7.9%). No significant difference was found between men and women, but the sexually transmitted disease (STD) prevalence was much higher in subjects younger than 20 years: 11.4% versus 3.6% (P < 0.01). In a logistic regression model, factors independently associated with STD infection were age younger than 20 years (OR, 2.6; P = 0.007), occasional sex partners (OR, 2.9; P = 0.007), and injection of drugs (OR, 2.8; P = 0.002) in the preceding 6 months., Conclusions: A moderate STD prevalence was found in the study population. The prevalence, however, can be considered high (>10%) among street youth and young sex workers. Providing community-based STD screening and treatment services appear to be an efficient method for reaching these high-risk groups.

Phenotypic and genotypic methods identify subtypes of Legionella pneumophila, serogroup 1, and match patient and environmental isolates from suspected sources. The strength of this association is limited by the lack of information regarding the frequency and distribution of isolates belonging to various subtypes. In this study, 62 clinical isolates of L. pneumophila, serogroup 1, were subtyped by using pulsed-field gel electrophoresis (PFGE), to determine the distribution and degree of diversity of PFGE patterns among monoclonal antibody (MAb) subtypes. Unexpectedly, 8 of 21 MAb Philadelphia 1 isolates had a common PFGE pattern, and, among 12 MAb OLDA isolates, only 2 PFGE patterns were seen. Our hypothesis was that PFGE patterns were distributed randomly; however, statistical analysis showed that the distribution of subtypes was not random (Fisher's exact test 0.13; P>.05). In light of these results, researchers who do epidemiological investigations should use caution when interpreting the significance of matching PFGE patterns of L. pneumophila, serogroup 1.

The objective of this study was to evaluate the diagnostic performance of the Roche multiplex AMPLICOR Chlamydia trachomatis/Neisseria gonorrhoeae PCR test for the detection of Neisseria gonorrhoeae infection in female urine specimens and wet and dry endocervical swabs. Endocervical swabs and urine specimens were collected from 342 female sex workers from Cotonou, Benin, and were tested using the AMPLICOR C. trachomatis/N. gonorrhoeae test (Roche Diagnostic Systems, Inc., Branchburg, N.J.) with internal control detection. Endocervical swabs were also cultured on Thayer-Martin medium. A series of alternate standards that included a combination of all the tests but not the test being evaluated was used to assess the performance of the test with each type of specimen. The sensitivity, specificity, and positive and negative predictive values for the urine were 53.8, 98.9, 93.5, and 87.5%, respectively. Corresponding figures for the wet swab were 91.5, 100, 100, and 97.4%, respectively. Those for the dry swab were 96.3, 96.2, 88.5, and 98.8%, respectively. Based on this study, the AMPLICOR PCR assay showed a low sensitivity for detection of N. gonorrhoeae infection in urine specimens, whereas the test was found to be highly sensitive and specific with endocervical specimens.

Neutralizing antibody titers of 47 infants whose mothers sustained measles (measles group) and 70 whose mothers were vaccinated (vaccine group) were compared at birth, 4 and 8 months of age. All children had antibodies at birth and 88% at 4 months. At 8 months, 49% had antibodies in the measles group and 15% in the vaccine group (P < 0.001). The geometric mean titers were significantly lower in the vaccine group than in the measles group and the difference corresponded to the antibody loss occurring in only 1.5 months of life. This small difference may reflect past exposure to wild virus of many vaccinated mothers.

The levels of antibody against measles, mumps, and rubella were determined at 5-6 years postimmunization in 468 children vaccinated with two different trivalent vaccines. The proportions of children without detectable antibody levels were 12 and 3.6% for measles (p < 0.001), 14.9 and 7% for mumps (p = 0.006), and 3.3 and 3.1% for rubella (p = 0.88), respectively, in MMR II and Trivirix recipients. A higher proportion of those vaccinated at younger ages had undetectable or low levels of measles antibody. These data indicate that a large proportion of children vaccinated under routine conditions do not have detectable measles and mumps antibody.

Erythromycin, the standard treatment for chlamydial infection in pregnant women, commonly causes side-effects, which limits its efficacy. In a randomised, double-blind study, we compared amoxycillin with erythromycin in this setting. 210 pregnant women with Chlamydia trachomatis infection were randomly assigned 7 days' treatment with amoxycillin (500 mg three times daily) or erythromycin (500 mg four times daily). Control cultures were obtained 21 days after treatment, during late pregnancy, and from the infant within a week of birth. Treatment was judged a failure if any post-treatment culture was positive or if the patient had to stop therapy because of severe side-effects. 11 women (5.2%) were lost to follow-up. 1 (of 100) amoxycillin-treated women had to stop treatment because of severe side-effects compared with 12 (of 99) erythromycin-treated women (p = 0.002). 1 woman in the amoxycillin group had a positive culture at the third-trimester examination. No positive post-treatment culture was found in the erythromycin group. Severe gastrointestinal side-effects were more common in women who received erythromycin (31 vs 6%, p < 0.001). The overall failure rate was therefore 2% in the amoxycillin group and 12% in the erythromycin group (p = 0.005). These results suggest that amoxycillin is an acceptable alternative to erythromycin for C trachomatis infection in pregnant women.

Objective: To measure the HIV seroprevalence rate in a surrogate sample of the general population in the province of Quebec, using a network of sentinel hospitals., Design: Anonymous unlinked sentinel surveillance study., Setting: Outpatient surgery units in 19 acute care hospitals throughout Quebec., Participants: All patients attending the outpatient surgery units from November 1990 to October 1992. A total of 61,547 plasma samples were obtained from leftover blood samples collected for cell counts. Fifty samples were excluded because of an insufficient amount of plasma and one because of an indeterminate result., Intervention: HIV antibody testing with enzyme-linked immunosorbent assay; positive results confirmed with radioimmunoprecipitation assay., Outcome Measures: HIV antibody status, sex, year of birth and area of residence., Results: The crude seroprevalence rate among the subjects aged 15 years or more was 0.4 per 1000 population (95% confidence interval [CI] 0.2 to 0.7) among the women and 3.6 per 1000 population (95% CI 2.8 to 4.4) among the men (p < 0.001). The rate after adjustment for age, sex and geographic distribution of the study population was 2.3 per 1000 population (95% CI 1.9 to 2.7). The seroprevalence rate among the male patients in the City of Montreal was much higher than the rates elsewhere in the province. It increased progressively during each of the four 6-month intervals of the study: 8.1, 8.7, 13.9 and 18.3 per 1000 respectively (chi 2 linear trend = 4.76; p = 0.029). No similar trends were observed outside Montreal for the male patients. There were too few seropositive female patients to draw any solid conclusion., Conclusions: Despite the possible drawbacks of a nonrandomized sampling scheme, this study suggests that in the male population the HIV seroprevalence rate is increasing in Montreal and is stable in all other areas of the province. The continued surveillance of HIV infection through anonymous unlinked studies is useful to monitor trends.

Objective: To compare the safety, tolerance and prophylactic effectiveness of a single 2-g dose of cefotetan with a standard prophylactic regimen of cefoxitin in reducing the incidence of postoperative infections after elective, open biliary tract surgery., Design: Multicentre, double-blind, randomized comparative study with a 4-week follow-up., Setting: Five Canadian university centres., Participants: One hundred and eleven patients scheduled to undergo elective, open biliary tract surgery., Interventions: The patients were randomly assigned to receive either cefotetan or cefoxitin in a ratio of 2:1; 76 patients received cefotetan and 35 received cefoxitin., Main Outcome Measures: Wound infection as defined by the Centers for Disease Control and Prevention and by clinical evaluation, adverse events and laboratory parameters., Results: Two incisional wound infections were reported by patients in the cefotetan group, for an overall infection rate of 1.8% (2 of 111). No significant differences were found in the failure rate or in any other indicator of efficacy. The incidence of adverse events for cefotetan (12.6%) was not statistically different from that for cefoxitin (10.4%), and none of the 16 adverse events in the cefotetan group and 5 in the cefoxitin group was serious or severe. Only one event (rash) was possibly related to the study drugs. Several hematologic and biochemical parameters were found to be normal preoperatively and abnormal postoperatively, but no relation was found between these variations and the study drugs. These changes were mainly attributable to the operation., Conclusion: Cefotetan was found to be effective and comparable to cefoxitin, both in safety and in reducing the incidence of infection after elective, open biliary tract surgery.

Objective: To assess the prevalence and risk factors for chlamydial infection in pregnant women in the Quebec City area and to propose strategies for a screening program., Methods: From January 1990 to July 1991, pregnant women from six centers were cultured for Chlamydia trachomatis. One hundred thirty-six with positive results and 536 with negative results were included in a case-control study on risk factors for this infection., Results: The prevalence of C trachomatis was 1.9% (136 of 7305). In a logistic regression analysis, young age (P < .0001, test for trend), nulliparity (odds ratio [OR] 3.3; P < .00001), and a new sexual partner in the last year (OR 3.3; P = .0012) were independently associated with infection. With screening restricted to pregnant women under age 25 or those with at least one risk factor, 81.7% of women positive for C trachomatis would have been detected, whereas only 40.6% of all women would have been cultured., Conclusion: In a low-prevalence area for chlamydial infection in pregnant women, pre-screening criteria could optimize the use of specific diagnostic tests.

Objectives: To assess temporary expatriation as a risk factor for HIV infection in a rural area of Senegal and to examine the transmission of HIV from expatriates to their families., Design: Cross-sectional study in identified expatriates and in a representative cluster sample of the general population from the same geographical area in northern Senegal., Methods: In 1989, a survey (including questionnaire and serological tests for HIV-1 and HIV-2) was conducted in all expatriates currently living in 11 villages in northern Senegal and spouses of all expatriates (present or not) from this area ('expatriate' group, n = 258). In parallel, a cluster sample of 600 adults was drawn from eight villages of the same area, of whom 414 were selected as the control group since they and their spouses had not travelled outside Senegal in the last 10 years., Results: In the 'expatriate' group, sera from 39 subjects were confirmed as HIV-positive by Western blot [17 out of 63 men (27.0%) and 22 out of 195 women (11.3%)]. Of these subjects, 33 were infected by HIV-1, four by HIV-2 and two had a dual HIV-1/2 profile. In contrast, only two subjects (one man and one woman) from the control group were infected by HIV-2 and none by HIV-1. In men, HIV-1 seroprevalence was associated with age < 40 years [odds ratio (OR), 7.4; P = 0.03] and previous sexually transmitted disease (STD) symptoms (OR, 13.5; P = 0.03), whereas the risk factors in women were age < 25 years (OR, 3.7; P = 0.04), being a widow (OR, 30.4; P < 0.01) and presence of sexual activity over the last 2 years (OR, 21.3; P < 0.01)., Conclusions: Penetration of HIV-1 infection in a country where HIV-2 is endemic shows that the HIV-1 epidemic is currently spreading to rural West Africa. Migrant workers appear to play a major role in this epidemic.

The in-vitro activity of RP 59500, a new semisynthetic injectable streptogramin, was compared with that of erythromycin, rifampicin and ciprofloxacin against 189 Legionella spp. Rifampicin was the most active agent tested. RP 59500 was found to be more active than erythromycin against most strains, but less active than ciprofloxacin. Legionella pneumophila serogroups 1, 3, 4, 5 and 6 were more susceptible to RP 59500 than were L. pneumophila serogroups 2, 7, and 8. Legionella micdadei was the least susceptible species to RP 59500 and erythromycin. RP 59500 was similar in activity against isolates obtained from both patients and environmental sources. This activity was generally better than that of erythromycin.

Seroprevalence of antibodies against human herpesvirus 6 was determined in a sample of 303 randomly selected individuals from the Quebec City area. The influence of different variables on antibody litres was also evaluated. Human herpesvirus 6 was grown in the HSB-2 cell line, and antibody litres were measured by indirect immunofluorescence. Serum samples were collected from 177 females and 126 males ranging in age from two months to 88 years. Ninety-nine per cent (300 of 303) of this population had an antibody titre of at least 1:10, whereas 75% had a titre of at least 1:80. Women had a higher geometric mean litre than men (P=0.06). This difference between sexes varied according to age and became statistically significant in subjects older than 20 years of age (P=0.04). It was found that this difference was attributable to higher antibody litres in women in the 15 to 40 year age group who had previously had children.

The objective of this study was to compare an indirect immunofluorescence assay with culture methods for the identification of Legionella pneumophila serogroups 1 to 6 in hot water samples taken from domestic environments. Hot water samples were obtained from the water heater, the shower heads, and the most frequently used faucet of 211 private houses. Concentrated water samples were inoculated on buffered charcoal yeast extract agar (BCYE) and on a semi-selective culture medium (GPV). Colonies with a morphology similar to that of Legionellaceae were subcultured on BCYE and on blood agar plates; those that grew on the former but not the latter were further characterized and identified by direct immunofluorescence techniques. The concentrated samples were also smeared on multiple-well microscope slides and tested by indirect immunofluorescence with monoclonal antibodies against L. pneumophila, serogroups 1 to 6. Of the houses studied, 30% were found to contain culturable L. pneumophila in at least one water sample, whereas 63% were positive by indirect immunofluorescence. The sensitivity of this assay compared with culture varied from 16.7-21.1%, and its specificity was between 76.7% and 88.3% depending on the sample source (water heater, shower heads, or faucet). In the 38 houses with at least one positive sample found by both immunofluorescence and culture, total or partial agreement between serogroups identified by both techniques was only 34%. The results obtained in this study strongly suggest that indirect immunofluorescence is not an adequate alternative for the identification of L. pneumophila in hot water systems.

Ten human sera were used to study different parameters, namely, methods of smear preparation and fixation, and age of infected HSB-2 cells in order to optimize indirect immunofluorescence assay (IFA) and anticomplement immunofluorescence (ACIF) procedures to measure antibody levels against HHV-6. Results showed a greater sensitivity of rapid smear drying and methanol fixation over conventional acetone smear preparation. Cells harvested 6 days after infection and fixed with methanol exhibited a sharper and more intense fluorescence. IFA titers were higher than those obtained with ACIF, although the latter procedure enabled the distinction between three fluorescent sites. Reactivity pattern of individual sera against infected cells was variable and indicated that the human immune response to HHV-6 is directed against different antigens. An easier interpretation and a better definition of the fluorescence of HSB-2 cell line infected with HHV-6 strain Dv is obtained with the following conditions: cells should be harvested at 5-8 days after infection (at the giant cell stage of infection), cell smears have to be dried quickly before fixation with methanol at -20 degrees C, and finally, they should be stained by IFA.

To identify factors associated with the contamination of hospital water distribution systems by legionellae, 84 Quebec hospitals provided 3284 hot water specimens from 839 different sites. Concentrated samples were seeded on buffered charcoal yeast extract agar and a semi-selective medium. At least one water sample was contaminated by legionellae in 57 hospitals (67.9%). In 22 hospitals (26.2%), greater than 30% of samples were contaminated by these bacteria. In 9 (12.2%) of 74 hospitals, distilled water was colonized. The presence of at least one positive sample was found to be associated with localization and number of hospital beds (P = .02 for both). Heavy contamination was associated with large volume hot water tanks (P = .01), low water temperature at faucet (P = .03), and old water heaters (P = .06). Conditions required for the occurrence of nosocomial legionellosis may be present in numerous hospitals.

To assess risk factors associated with the contamination of the domestic environment by legionellae, 211 houses in the Quebec City area were randomly selected and water samples were collected from the hot water tank, the shower heads, and the most frequently used faucet. After centrifugation, concentrated samples were seeded in triplicate on BCYE and GPV media. Data on the characteristics of the hot water system and plumbing in the house and on the personal habits of the occupants were collected for each house. Among these 211 houses, hot water was provided by either an oil or gas heater in 33 and by an electric heater in 178. Legionellae were isolated from none of the samples from houses with oil or gas heaters and from 39% (69 of 178) of those with electric water heaters (P less than 0.0001). This association remained highly significant after control for water temperature and other variables in a stratified analysis. In the 178 houses with an electric heater, 12% of the faucets, 15% of the shower heads, and 37% of the water heaters were contaminated. Legionella pneumophila serogroups 2 and 4 were the most frequently isolated strains. Logistic regression showed that factors associated with electric water heater contamination were (i) location of the house in older districts of the city (P less than 0.0001), (ii) old age of the water heater (P = 0.003), and (iii) low water temperature (P = 0.05). Contamination of the water heater was the only factor significantly associated with the contamination of peripheral outlets (P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

The 1989 measles outbreak in the province of Quebec has been largely attributed to an incomplete vaccination coverage. In the Quebec City area (pop. 600,000) 1,363 confirmed cases of measles did occur. A case-control study conducted to evaluate risk factors for measles allowed us to estimate vaccination coverage. It was measured in classes where cases did occur during the outbreak. This population included 8,931 students aged 5 to 19 years old. The 563 cases and a random sample of two controls per case selected in the case's class were kept for analysis. The vaccination coverage among cases was at least 84.5%. Vaccination coverage for the total population was 99.0%. Incomplete vaccination coverage is not a valid explanation for the Quebec City measles outbreak.

The routine use of monoclonal antibodies against L. pneumophila and other Legionellaceae has not yet reached the clinical microbiology laboratory. Most of these antibodies are still under evaluation and are not available commercially. However, it is obvious that some of them will be available in the next few years. Because of the numerous subtypes and serogroups of L. pneumophila already identified, extreme caution must be used before they are adopted routinely by a given laboratory. Testing against a large number of strains will have to be performed, and even then unidentified subtypes may not be recognized. Monoclonal antibodies against species-specific antigens of Legionella may prove to be the most useful for routine work, but once again a large number of strains will have to be tested before they are adopted. Under certain circumstances and especially in epidemiologic studies, well-chosen anti-L. pneumophila serogroup 1 monoclonal antibodies that define different subtypes may prove to be invaluable. This is currently the area in which the use of monoclonal antibodies against L. pneumophila is best defined.

The in vitro activity of lomefloxacin (SC-47111 or NY-198) was compared with those of erythromycin and rifampin against a total of 180 Legionella spp. strains isolated from nosocomial or acquired respiratory tract infections and from environmental sources. Rifampin was the most active agent tested (MIC90, 0.008 microgram/ml) against Legionella spp. However, lomefloxacin was found 2-to-4-fold more active than erythromycin against most Legionella strains tested. Against Legionella pneumophila, lomefloxacin (MIC90, 0.12 microgram/ml) was significantly more than erythromycin (MIC90, 0.5 micrograms/ml). L. pneumophila serogroup 2, 3, and 5 strains (MIC90, 0.06 micrograms/ml) were more susceptible than L. pneumophila serogroup 1, 4, 6, 7, and 8 (MIC90, 0.12 microgram/ml). L. dumoffii was the most resistant species with a MIC90 of 0.25 microgram/ml and 0.5 microgram/ml, respectively, to lomefloxacin and erythromycin. The activity of lomefloxacin was similar against the isolates obtained from patients or from environmental sources.

One hundred environmental water samples, which were collected in the Quebec city area and cultured on buffered charcoal yeast extract medium and three selective media, were inoculated to guinea pigs and were screened by direct immunofluorescent staining (DFA) for the presence of Legionellaceae. Six isolates were made (four Legionella pneumophila and two Tatlockia (Legionella) micdadei: three by animal inoculation and three by culture). No samples were simultaneously positive by both methods. After screening by DFA, 43 of the 100 samples were positive for Legionellaceae and 27 of those contained more than one serogroup and (or) species of Legionellaceae. Legionella pneumophila (serogroups 1 to 6) was the most frequent species seen by DFA. These results clearly show that Legionellaceae are frequent members of the freshwater microbial flora of the Quebec city area.

A panel of monoclonal antibodies to Legionella pneumophila serogroup 1 and a subclassification scheme were developed in a collaborative project among three laboratories. The seven most useful monoclonal antibodies were selected from three previously developed panels on the basis of indirect fluorescent antibody patterns with 83 strains of L. pneumophila serogroup 1 that were obtained from widely distributed geographic locations. The isolates were divided into 10 major subgroups on the basis of reactivity patterns that can be readily reproduced in any laboratory and are not subject to major inconsistencies of interpretation of staining intensity. A standard protocol for the indirect fluorescent antibody procedure was also developed.

Despite the fact that incidence studies of sexually transmitted diseases have rarely been performed in rural areas, it is generally assumed that the frequency of such diseases in rural areas is lower than in cities. We studied the incidence of four sexually transmitted diseases in a rural community (population 150,000) located in southern Quebec. Between March and September 1986, a random sample of 41 of 123 general practitioners reported all cases of syphilis, gonorrhea, chlamydial genital infection, and genital herpes at the time of diagnosis. In addition, all the specialists of the area who regularly diagnose sexually transmitted diseases reported their cases. For each case contact tracing was attempted. The estimated incidence rate was 584 per 100,000 person-years for at least one of the studied diseases. For chlamydia, gonorrhea, and herpes, the rates per 100,000 person-years were 470, 149, and 36, respectively. Over 11% of the cases had more than one of these diseases. Of the 114 index cases diagnosed by physicians, 102 were symptomatic, whereas of the 62 contact cases, only 25 were symptomatic (p less than 0.001). In addition, for genital chlamydial infection 84% of female cases were primarily diagnosed by physicians, whereas 64% of male cases were found by contact tracing (p less than 0.001). This study shows that sexually transmitted diseases are a major public health problem in rural communities.

Monoclonal antibodies directed against Legionella pneumophila serogroups 1 to 6 were produced by fusing splenocytes of BALB/c mice with the Sp 2/0-Ag14 or the NSO mouse myeloma cell lines. Specificity of these antibodies was determined by indirect fluorescent-antibody staining: 8 reacted with L. pneumophila serogroup 1 and, respectively, 13, 6, 6, 5, and 10 reacted with serogroups 2, 3, 4, 5, and 6; all except 5 were serogroup specific, and none presented cross-reactions with six other species of Legionellaceae. Serogroup determination of 35 isolates of L. pneumophila with seven selected monoclonal antibodies resulted in correct serogrouping in all instances; a pool of the same seven monoclonal antibodies stained intensely all strains of L. pneumophila without any staining of the other species of Legionellaceae. When 24 serogroup 1 isolates of L. pneumophila were stained with eight serogroup 1-specific monoclonal antibodies, the staining patterns could be clustered in five distinct groups. These hybridomas thus represent an unlimited source of standard reagent that could be used in the detection and serogrouping of L. pneumophila; differences in staining patterns could be used as epidemiological markers for these bacteria.

The antigens of the six serogroups of Legionella pneumophila were compared by two-dimensional (crossed) immunoelectrophoresis by using rabbit antisera to serogroups 1, 2, 3 and 4. The close relationship among the serogroups was shown by the fact that 27 of the 31 antigens demonstrated so far were common. However, distinctive group-specific antigens with slow electrophoretic mobility were observed for serogroups 1, 2, 3, and 4. When intact serogroup 1 organisms were extracted with EDTA, the group-specific antigen was recovered in a virtually pure form. The group-specific antigen was pronase resistant, heat stable, and amphiphilic and had a surface location, all of which are properties suggestive of lipopolysaccharide. L. pneumophila shared four to five antigens with Tatlockia micdadei (Legionella micdadei). The large number of common antigens in the serogroups of L. pneumophila has important implications for the specific detection of antigens and antibodies by fluorescent and other tagged antibody methods.

Twenty-five clinical isolates of Legionella pneumophila serogroup I were classified as epidemic or sporadic on epidemiological grounds. All were isolated from patients at the Medical Center Hospital of Vermont (MCHV) in Burlington between 1977 and 1983. These coded isolates were examined with a panel of eight monoclonal antibodies to serogroup 1 and an indirect microimmunofluorescent test. Strains from 14 of the 15 MCHV epidemic cases had one staining pattern (A); isolates from eight of nine MCHV sporadic (nosocomial) cases had a different pattern (B). One sporadic strain was of staining pattern A, and in one epidemic case an isolate of each pattern (A and B) was obtained. The only case that was clearly community-acquired displayed a third staining pattern (C). Four isolates from the cooling tower considered the most likely source for the epidemic strains had an antigenic reaction identical to isolates in epidemic cases, whereas three strains from the potable water system displayed an antigenic pattern identical to isolates in sporadic cases.

Serogroup-specificity of Legionella pneumophila is related to lipopolysaccharide (LPS), and few cross-reactions between serogroups have been observed with rabbit or monkey antisera. C57BL/6 mice were sequentially immunized with crude outer membrane fractions of L. pneumophila serogroups 1, 5, and 7, Legionella bozemanii, and Legionella micdadei. Spleen cells from these mice were then fused with the Sp2-0/Ag14 mouse myeloma cell line. Outer membrane-rich fractions and LPS were prepared from L. pneumophila serogroups 1 to 8 and other Legionella and non-Legionella species. Immunoblots of these extracts were performed with monoclonal antibody obtained from these fusions. One of these monoclonal antibodies recognized an epitope common to all tested serogroups of L. pneumophila and attached to the major constituent of the outer membrane, LPS. This antibody did not react with other Legionella species and numerous gram-negative rods other than Pseudomonas fluorescens CDC93. This monoclonal antibody may be useful in preliminary identification of L. pneumophila as an alternative to direct fluorescent-antibody testing.

Five cases of Legionnaires' disease caused by Legionella dumoffii were identified within an 11-month period in a hospital in the Quebec City area. In four cases bacterial isolates were obtained from clinical specimens, and in one case seroconversion was demonstrated. All the patients had been admitted to hospital within 10 days before diagnosis. Two of the patients were immunosuppressed children. Only 1 of the 40 hot water samples from the hospital yielded L. dumoffii; however, 6 of 11 distilled water samples contained the bacterium. All the patients had been exposed to distilled water, four through respiratory therapy equipment and one through a room humidifier. Following the use of sterile distilled water in the apparatus, no further cases were identified. This is the first reported outbreak of Legionnaires' disease caused by L. dumoffii, and it is the first time that nosocomial legionellosis has been linked to contaminated distilled water in Canada.

Multilocus enzyme electrophoresis, monoclonal antibody typing for Legionella pneumophila serogroup 1, and plasmid analysis were used to type 89 L. pneumophila strains isolated from nosocomial cases of Legionnaires disease at the Veterans Administration Wadsworth Medical Center (VAWMC) and from the hospital environment. Twelve L. pneumophila clinical isolates, obtained from patients at non-VAWMC hospitals, were also typed by the same methods to determine typing specificity. Seventy-nine percent of 33 VAWMC L. pneumophila serogroup 1 clinical isolates and 70% of 23 environmental isolates were found in only one of the five monoclonal subgroups. Similar clustering was found for the other two typing methods, with excellent correlation between all methods. Enzyme electrophoretic typing divided the isolates into the greatest number of distinct groups, resulting in the identification of 10 different L. pneumophila types and 5 types not belonging to L. pneumophila, which probably constitute an undescribed Legionella species; 7 clinical and 34 environmental VAWMC isolates and 2 non-VAWMC clinical isolates were found to be members of the new species. Twelve different plasmid patterns were found; 95% of VAWMC clinical isolates contained plasmids. Major VAWMC epidemic-bacterial types were common in the hospital potable-water distribution system and cooling towers. Strains of L. pneumophila which persisted after disinfection of contaminated environmental sites were of a different type from the prechlorination strains. All three typing methods were useful in the epidemiologic analysis of the VAWMC outbreak.

The outer membrane proteins of Legionella pneumophila serogroups 1 to 8 were prepared from broken cells by selective solubilization using sodium lauryl sarcosinate. The isolated proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. Rabbit antisera against each of the eight serogroups of L. pneumophila were obtained by immunizing each animal with live bacteria. The transferred proteins were revealed using these antisera and peroxidase-labeled swine anti-rabbit immunoglobulins. Antigenic determinants common to all eight serogroups were found in at least three outer membrane antigens (19, 29, and 45 kilodaltons (kDa)). However, cross-absorption experiments revealed that these three antigens were immunologically related, but not identical among serogroups. The antigenic relationships observed with two of these three antigens correlated well with cross-reactions observed in immunofluorescence. When a monoclonal antibody directed against L. pneumophila serogroup 1 lipopolysaccharide was used to reveal a blot of serogroup 1 outer membrane antigens, the 29- and 45-kDa bands appeared. This demonstrates a strong association between lipopolysaccharide and outer membrane proteins.