Endemicity of cholera in Surabaya, Indonesia.

As the seventh pandemic of cholera is caused by V. cholerae biotype El Tor, the former criteria for endemicity of cholera need to be reconsidered as regards their applicability in areas that are infected with cholera. As the mortality rate of cholera nowadays can be reduced to a very low level due to modern methods of treatment, it is suggested that the infection rates of cholera should be taken into consideration as criteria of cholera endemicity, i.e. 1. Five years persistence of cholera cases in a given area. 2. Five percent infection rate among family contacts of cholera cases. 3. Minimum infection rate of 1% in a vicinity where cholera cases occur. It was also found that in such an endemic area it is very difficult to eliminate V. cholerae infection from a locality, even when all family contacts are treated with the full dose of tetracycline.

Titration of cholera antitoxin in human sera by microhemagglutination with formalinized erythrocytes.

Microtiter hemagglutination tests employing formalinized sheep erythrocytes sensitized with either crude or purified cholera toxin were used to assay the cholera antitoxin content of human sera. Comparable results were obtained with either crude or purified toxin-sensitized cells with the exception of two sera that gave unusually high hemagglutination titers with the crude toxin. Sera from 13 convalescent cholera patients showed a high degree of correlation between antitoxin levels as determined in vitro by the hemagglutination test and in vivo by the skin permeability factor neutralization test. Fourfold or greater rises in antitoxin levels between acute and convalescent sera were detected in 9 of 15 patients with bacteriologically proven cholera. No significant increases in titer were observed in 14 cases of noncholera diarrhea. Cholera antitoxin was detected by hemagglutination in only 1 of 33 sera, obtained from eight countries, containing vibriocidal antibodies. Formalinized sheep erythrocytes sensitized with toxin and stored at 4 C in the presence of 1:10,000 thimerosal were stable and sensitive for at least 6 months (the longest time tested).

Enhancement by sodium chloride of the selectivity of thiosulfate citrate bile salts sucrose agar for isolating Vibrio cholerae biotype El Tor.

In this study we utilized the salt-tolerant characteristics of vibrios to develop a more selective medium by addition of NaCl to thiosulfate citrate bile salts sucrose (TCBS) agar. The effect of adding salt to TCBS agar varied greatly among brands of TCBS agar and between lots of the same brand. The addition of salt at concentrations as high as 1.5% (2.5% total NaCl) caused the inhibition of growth of three species of commonly encountered normal bowel flora and one strain of classical Vibrio cholerae but did not compromise the use of TCBS agar for isolation of V. cholerae biotype El Tor.

Panel of reference strains for evaluating serologic reagents used to identify gonococci.

A panel of strains for evaluating Neisseria gonorrhoeae serologic reagents was developed. The strains selected for the panel were antigenically diverse and representative of strains isolated worldwide and had been isolated from a variety of anatomic sites. A few strains with characteristics that can cause problems in serologic tests were included. The panel of 52 gonococcal and 20 nongonococcal strains was used to evaluate two commercially produced kits with monoclonal antibody reagents, GonoGen and Phadebact, and one Phadebact kit with absorbed rabbit antiserum. The GonoGen reagent correctly identified all gonococcal strains and did not react with any of the nongonococcal strains. The Phadebact absorbed antiserum reagent correctly identified 47 of 48 gonococcal strains but reacted with 2 of the 20 nongonococcal strains. The Phadebact monoclonal antibody reagent correctly identified all the gonococcal strains; however, it gave positive reactions with 8 and trace reactions with 4 of the 20 nongonococcal strains.

Chromosomally mediated resistance in Neisseria gonorrhoeae in the United States: results of surveillance and reporting, 1983-1984.

Between January 1983 and October 1984, 446 cases of infection due to chromosomally mediated resistance in Neisseria gonorrhoeae (CMRNG) were reported in 23 states. Eighty percent were detected as primary penicillin or ampicillin treatment failures. Gonococcal isolates were submitted from 175 (40%) for confirmation of resistance, susceptibility testing, gonococcal strain typing using monoclonal antibodies specific for outer membrane Protein I, and auxotyping. All were typed as Protein I serogroup IB (WII/WIII), and the majority were proline or prototrophic auxotypes. All were resistant in vitro to less than 1 microgram/ml of either penicillin or tetracycline. Comparing CMRNG with penicillinase-producing Neisseria gonorrhoeae (PPNG), we found that CMRNG were significantly more resistant to tetracycline and erythromycin, but PPNG were more resistant to penicillin (P less than .01). Because of increasing reports of gonococcal resistance in the United States, improved surveillance of clinical and laboratory resistance is needed in support of control and treatment recommendations for gonorrhea.

A controlled field trial of plain and aluminium hydroxide-adsorbed cholera vaccines in Surabaya, Indonesia, during 1973--75.

A controlled field trial comparing the effectiveness of a plain cholera vaccine with that of a vaccine adsorbed to aluminium hydroxide was carried out in a cholera-endemic area of Indonesia during 1973-75. Tetanus toxoid adsorbed to aluminium phosphate was used as the control. In vaccinees aged 1-4 years, the adsorbed cholera vaccine provided about 88% protection for 6 months following vaccination and still provided about 50% protection between 11 and 14 months after vaccination. In the same age group, the plain vaccine provided only 53% protection during the first 6 months and no appreciable protection beyond that period. In those aged 5 years and over, both vaccines provided 50-60% protection throughout the period of observation (14 months). Neither vaccine caused any serious side effects.

Characterization of concatemeric plasmids of Neisseria gonorrhoeae.

Three strains of Neisseria gonorrhoeae carried novel plasmids of 7.8 megadaltons (mdal) molecular mass in addition to plasmids previously observed in this organism. The presence of the 7.8-mdal plasmids was not accompanied by any distinguishable phenotype in the strain possessing them. Analysis of plasmid DNA with restriction endonucleases showed that these plasmids were composed of three directly repeated copies of a 2.6-mdal cryptic plasmid frequently found in N. gonorrhoeae. In addition, the 7.8-mdal plasmids exhibited characteristics common to the 2.6-mdal plasmid, structural lability and sites resistant to cleavage with HpaII. The concatemeric forms of the cryptic plasmid appear to be stable in these strains and do not undergo internal recombination to produce the 2.6-mdal monomer, nor were higher concatemers detected.

A case of cholera in Texas, 1973.

The first naturally acquired case of cholera reported in the United States since 1911 occurred in a 51-year-old resident of Port Lavaca, Texas. Extensive epidemiologic investigation of the patient's contacts and environment did not identify a cholera carrier of elucidate a pathway of transmission, but several avenues of investigation suggested possible means by which the patient may have acquired his infection. No secondary spread resulted from this case, and its occurrence did not endanger the community at large.

Serologic studies of naturally acquired infection with Vibrio cholerae serogroup O1 in the United States.

The discovery of 11 persons infected with Vibrio cholerae serogroup O1 (biotype El Tor, serotype Inaba) in southwestern Louisiana in 1978 provided an opportunity to evaluate the serologic response to this agent in North Americans with naturally acquired infection. One antibacterial assay (vibriocidal assay) and two antitoxin assays (enzyme linked immunosorbent assays [ELISA] and rabbit skin permeability factor assay) were used. Antitoxin levels were elevated longer than vibriocidal antibody levels, and asymptomatic infected persons had levels of antitoxin and vibriocidal antibody levels, and asymptomatic infected persons had levels of antitoxin and vibriocidal antibody as high as those of persons with clinical cholera. With use of serologic criteria derived from these studies, one additional person infected with V. cholerae O1 was discovered, and a relatively low (4%-7%) prevalence rate of elevated levels of vibriocidal antibody and antitoxin was found in a serum survey of a community with several known cases. Comparison of the results from the ELISA and the rabbit skin permeability factor assay demonstrated similar rates of elevated levels of antitoxin, but the ELISA required less time and less serum per sample analyzed.

Laboratory investigation of diarrhea in travelers to Mexico: evaluation of methods for detecting enterotoxigenic Echerichia coli.

A laboratory investigation was conducted on cultures collected from travelers before, during, and after a trip to Mexico to characterize the etiology of traveler's diarrhea. Four laboratory methods for detecting enterotoxigenicity of Escherichia coli were evaluated: the infant mouse assay, the Chinese hamster ovary (CHO) cell assay, the Y1 adrenal cell assay, and the rabbit ileal loop. Although a number of common enteric pathogens were identified as a cause of traveler's diarrhea, including six serotypes of Salmonella, two serotypes of Shigella, Vibrio parahaemolyticus, Giardia lamblia, and Entamoeba histolytica, enterotoxigenic Escherichia coli was most commonly isolated. Strains were identified that produced only heat-labile enterotoxin (LT), only heat-stable enterotoxin (ST), or both LT and ST. The infant mouse assay yielded results falling into two distinct groups, providing a clear separation of positive and negative cultures. The CHO assay also formed two groups, with positive cultures producing 11% or more of the elongated cells. There was good agreement between the CHO and the Y1 adrenal cell assays for detection of LT. The adrenal cell system for detection of LT was more suitable than the CHO assay for processing large numbers of specimens because of the miniculture modification of this method utilized in this study. The infant mouse method was a simple and reliable method for detecting ST.

Shigellosis at sea: an outbreak aboard a passenger cruise ship.

Between June 23 and June 30, 1973, 90% of 650 passengers and at least 35% of 299 crew members experienced a diarrheal illness during a 7-day Caribbean cruise aboard a passenger cruise liner. Symptoms were consistent with shigellosis, and Shigella flexneri 6, Boyd 88 biotype, was isolated from rectal swabs taken from 8 to 35 ill passengers and 33 of 294 crew members. Epidemiologic evidence incriminated the ship's water, including ice, as the probable vehicle of transmission, and elevated coliform counts were found in potable water samples obtained aboard the vessel at the peak of the outbreak. Potential sources of contamination of the vessel's potable water supply were investigated, and improvements in the loading and chlorination of potable water were recommended.

An outbreak of salmonellosis among children attending a reptile exhibit at a zoo.

OBJECTIVE: In January 1996, an outbreak of diarrhea caused by Salmonella Enteritidis occurred in children attending a Komodo dragon exhibit at a metropolitan zoo. We sought to determine the extent of the outbreak and mode of transmission. STUDY DESIGN: A case-control study was conducted. Controls were randomly selected from zoo membership lists and matched to patients by age group and date of exhibit visit. RESULTS: Of 65 patients identified, 39 had confirmed and 26 had suspected cases. The median age was 7 years (range, 3 months to 48 years); 55% were enrolled in the case-control study. No patients and two (4%) controls reported touching a dragon; however, 83% of patients but only 52% of controls touched the wooden barrier that surrounded the dragon pen (odds ratio = 4.0, 95% CI 1.2 to 13.9). Washing hands at the zoo after visiting the dragons was highly protective (OR = 0.14, 95% CI 0.03 to 0.7). Cultures from the patients, one dragon, and the exhibit barriers yielded Salmonella Enteritidis, phage type 8. On the basis of an attack rate of 4.3% among exhibit attendees under 13 years old on whom data were collected, we estimate that 315 additional cases of salmonellosis occurred among visitors in this age group. CONCLUSION: This large outbreak demonstrates the importance of environmental contamination in the transmission of Salmonella from reptiles, and the protective value of hand washing. Recommendations regarding reptile exhibits and reptilian pets should emphasize this indirect route.

Multicenter comparison of levels of antibody to the Neisseria meningitidis group A capsular polysaccharide measured by using an enzyme-linked immunosorbent assay.

There is no standard immunoassay for evaluating immune responses to meningococcal vaccines. We developed an enzyme-linked immunosorbent assay to measure total levels of antibody to Neisseria meningitidis group A capsular polysaccharide. Five laboratories measured the antibody levels in six paired pre- and postvaccination serum samples by using the enzyme-linked immunosorbent assay. Methylated human serum albumin was used to bind native group A polysaccharide to microtiter plate surfaces. The between-laboratory coefficients of variation for pre- and postvaccination sera had ranges of 31 to 91 and 17 to 31, respectively. The mean laboratory coefficients of variation for pre- and postvaccination sera, respectively, were 17 and 11 (Molecular Biology Laboratory, Centers for Disease Control), 12 and 15 (Immunodiagnostic Methods Laboratory, Centers for Disease Control), 22 and 19 (Dana-Farber Cancer Institute), 38 and 38 (Bacterial Polysaccharide Laboratory, U.S. Food and Drug Administration), and 11 and 10 (Praxis Biologics, Inc.). Standardization of this enzyme-linked immunosorbent assay should allow interlaboratory comparison of meningococcal vaccine immunogenicity, thus providing a laboratory-based assessment tool for evaluating meningococcal vaccines.