Immune status against diphtheria among immigrants from the former USSR who arrived in Israel during 1990-1991.

Large outbreaks of diphtheria occurred recently in the former USSR. Between 1989 and 1994, a total of about 600,000 Soviet immigrants arrived in Israel. The immune status against diphtheria in a sample of 992 men aged 17-49 and 195 women aged 17-19, who arrived in Israel during 1990-91, was studied in order to evaluate the need for vaccination. Participants completed a self-administered questionnaire and diphtheria antitoxin antibody levels were measured by means of ELISA. At age 17-19, the prevalence of antitoxin antibody levels below the protective level of 0.01 IU/ml was 4.8% in the men and 2.1% in the women. Among the men, the percentage lacking protection declined from 4.8% at age 17-19 years to 1.6% at age 20-24, and increased to 18.2% at age 35-49. In the oldest group, the prevalence of those lacking protection was considerably higher than for the general Israeli population. In the multivariate analysis, age, mother's education and republic of origin were significantly associated with the absence of protection. Immigrants from the former USSR appear to be more susceptible to diphtheria, thus increasing the possibility of clinical disease, and it is recommended that they receive booster doses of diphtheria toxoid.

Long-term persistence of anti-diphtheria toxin antibodies among adults in Israel. Implications for vaccine policy.

Vaccination against diphtheria has essentially led to the disappearance of the disease in Israel. However, in other countries with high immunization coverage, isolated cases and small outbreaks have occurred in adults. Immunity following vaccination or natural exposure to toxigenic strains of C. diphtheriae is conferred by serum antibodies to diphtheria toxin. Since booster doses of diphtheria toxoid are recommended every ten years in adults, this raises the question of persistence of protective levels of anti-diphtheria toxin antibodies. In this study we assessed a possible age-related decline in anti-diphtheria toxin antibodies among adults in Israel. The study population comprised random samples in three age groups: 263 male recruits aged 18-19 years, 116 male reserve soldiers aged 25-35 years and 153 aged 41-51 years. Anti-diphtheria toxin antibody levels were measured by means of ELISA. Results indicate that 64.3% (95% CI = 58.5-70.1%) of those aged 18-19 had anti-diphtheria toxin levels in excess of 0.1 IU ml-1, whereas the corresponding figures for ages 25-35 and 41-51 were 32.8% (95% CI = 24.2-41.3%) and 15% (95% CI = 9.4-20.7%). However, even in the oldest age group, 95.4% (95% CI = 90.8-98.1%) had antibodies above the presumed protective level of 0.01 IU ml-1. Although these results indicate a significant age-related decline in anti-diphtheria toxin antibodies in vaccinated subjects, most had apparently protective levels. The absence of cases suggests that vaccine-induced immunity is long-lasting. However the immune status of the population should be carefully monitored.

A new Streptococcus group A M-29 variant isolated during a suspected common-source epidemic.

In the summer of 1988, a large epidemic of acute pharyngitis occurred in an Israeli military base. The clinical features were those of acute pharyngitis. The epidemic curve was characteristic of a common-source outbreak, possibly food-borne. Throat swabs from a sample of cases were positive for group A streptococci. Nine isolates from the epidemic were further evaluated at the local reference laboratory and serotyping showed that all were of the same strain with a distinct M protein that is a hitherto undescribed variant of M-29. We discuss the significance of unusual strains of beta-hemolytic Streptococcus appearing in food-borne outbreaks.

Prevalence and correlates of diphtheria toxin antibodies among young adults in Israel.

The paucity of information about immunity against diphtheria of young adults in Israel prompted us to analyse sera from a random sample of 480 recruits (263 males and 217 females) aged 18-19 years. Antitoxin antibody levels were determined by means of ELISA. Of the recruits 58.1% had antibody values greater than 0.1 IU/ml; 38.5% had amounts between 0.01 and 0.1 IU/ml, which is considered low when using the ELISA method, and 3.3% had less than 0.01 IU/ml. The results of this study suggest that a booster dose of antidiphtheria vaccine should be given to adults in Israel in order to ensure adequate antibody levels.

Salmonella serovars (others than Typhi and Paratyphi) from extra-intestinal sources. Israel, 1984-9.

The purpose of this study was to examine whether certain salmonella serovars, other than Typhi and Paratyphi, may have an increased ability to enter the human body fluids. The data are based on over 20,000 salmonella isolated from humans during 1984-9, among them 436 from extra-intestinal (EI) sources. The mean percentage of EI salmonella isolated in Israel (excluding Typhi and Paratyphi), was 2.1%. In three serovars: S.9, 12:1, v:-, Virchow and Saintpaul, the percentage of blood isolations and of EI isolations in general, was high. Among the frequent serovars, ser. Infantis and Hadar had a much lower percentage of EI isolations.

Improved medium for storage and transportation of thermophilic campylobacters.

A medium for storage and transportation of thermophilic campylobacter cultures was developed. The medium contains brucella broth with 0.16% or 0.3% agar, 5% human blood, a growth supplement which enhances aerotolerance and an antibiotic supplement. Using this medium all cultures tested were recovered after 48 days at 4 degrees C, 56 days at 37 degrees C and 32 days at room temperature. Some of the cultures even remained viable for up to three months at 4 degrees C and 56 days at room temperature. The blackening of the medium by H2S positive cultures offers an indication as to the biotype.

Correlation between cutaneous reaction in vaccinees immunized against smallpox and antibody titer determined by plaque neutralization test and ELISA.

The correlation between skin reaction, exhibited by vaccinees immunized against smallpox, and antibody titer determined by plaque neutralization and ELISA, was evaluated. Twenty eight out of 35 young adults (vaccinated at infancy and at the age of 8 years), who were injected with vaccinia virus, displayed a major skin reaction a week later. An increase of four-folds and more, in antibody titer against vaccinia virus, is generally considered positive immunization take-up against smallpox. According to this criterion, only 17 of the vaccinees were found positive by plaque neutralization, while 25 by the indirect micro-ELISA. Thus, there were eight vaccinees who were considered immunized by the ELISA, (seven of them also according to the skin reaction), but not by the plaque neutralization test.

Isolation and identification of pathogenic microorganisms at wastewater-irrigated fields: ratios in air and wastewater.

Samples of air and corresponding wastewater samples were taken at wastewater spray-irrigated fields. The concentrations of salmonellae and enteroviruses present in these samples were determined and compared with those of coliforms, and the ratios between them were calculated. The most common Salmonella serotype in the air was Salmonella ohio, whereas in the wastewater, Salmonella anatum was the most common. Enteroviruses isolated and identified were poliovirus, echovirus, and coxsackievirus type B. From the ratios of salmonellas to coliforms and enteroviruses to coliforms in the air, as compared to these ratios in the wastewater, it was concluded that the suitability of coliforms as an indication of airborne contamination caused by spray irrigation is questionable.

Measurement of the inactivation kinetics of poliovirus by ozone in a fast-flow mixer.

Inactivation kinetics of poliovirus type 1 in ozone demand-free water was investigated by utilizing a fast-flow mixing apparatus. Ozonated water and a solution of ozone demand-free water containing a known quantity of poliovirus type 1 were introduced simultaneously into a mixing chamber, both at a constant rate. This mixture was then passed through a narrow tube of known length and diameter into a neutralizing solution. By altering the rate of introduction and/or tube length, different contact periods between ozone and virus could be determined with an accuracy of 0.01 s. Inactivation of the poliovirus occurred in two steps. During the first step, which lasted for 0.2 to 1.0 s, 95 to 99% of the virus was inactivated, depending on the ozone concentration (which ranged from 0.1 to 2.0 mg/liter). The second step apparently continued for several minutes; in this period the remainder of the virus was inactivated. An obvious dose-response relationship was demonstrated during the first step of the inactivation curve. The pH of the water slightly affected the viral inactivation rate, but these small differences seem to have no practical value.

Unsuitability of polioviruses as indicators of virological quality of water.

Polioviruses could not be detected in about 50% of sewage samples despite routine administration of live attenuated poliovirus vaccine to the infant population.

High levels of microbial contamination of vegetables irrigated with wastewater by the drip method.

The public health aspects of the use of wastewater in agriculture and the effects of the drip irrigation method on the contamination of vegetables were studied. The method used was to simulate enteric microorganisms' dissemination by contaminated irrigation water in the field. The vegetables were irrigated with an effluent inoculated with a high titer of traceable microorganisms: poliovirus vaccine and a drug-resistant Escherichia coli. The dissemination of the marker organisms in the field was followed, and the effects of certain manipulations of the drip irrigation method on the contamination of the crops by the effluent were examined. It was shown that drip irrigation under plastic sheet cover with the drip lines placed either on the soil surface or buried at a depth of 10 cm significantly reduced crop contamination from inoculated irrigation water even when massive doses of bacteria and viruses were used. The microbial contamination was found to persist in the irrigation pipes and in the soil for at least 8 and 18 days, respectively. The data indicate that the recovery of the marker organisms was affected by soil texture and environmental conditions.

Airborne enteric bacteria and viruses from spray irrigation with wastewater.

The relationship between bacterial concentrations in wastewater used for spray irrigation and in the air was examined. Aerosolized coliforms were detected when their concentration was 10(3)/ml or more in the wastewater. Relative humidity and solar irradiation appeared to affect viable bacteria in the air; a positive correlation was found between relative humidity and the number of aerosolized bacteria. The correlation between solar irradiation and bacterial level, on the other hand, was negative. During night irrigation, up to 10 times more aerosolized bacteria were detected than with day irrigation. Wind velocity did not play an important role in the survival of aerosolized bacteria. Echovirus 7 was isolated in 4 out of 12 air samples collected 40 m downwind from the sprinkler.

Risk of communicable disease infection associated with wastewater irrigation in agricultural settlements.

The incidence of enteric communicable diseases in 77 kibbutzim (agricultural communal settlements) practicing wastewater spray irrigation with partially treated nondisinfected oxidation pond effluent is compared with that in 130 kibbutzim practicing no form of wastewater irrigation. The incidence of shigellosis, salmonellosis, typhoid fever, and infectious hepatitis is two to four times higher in communities practicing wastewater irrigation. No significant differences are found for the incidence of streptococcal infections, tuberculosis, and laboratory-confirmed cases of influenza. Nor are differences found for enteric disease rates during the winter nonirrigation season. Strong wastewater treatment measures, including effective bacterial and viral inactivation through disinfection, are recommended for all cases of sewage irrigation or land disposal near residential areas in light of the potential public health risks involved.

Organic flocculation: an efficient second-step concentration method for the detection of viruses in tap water.

A method is described for second-step concentration of viruses from water. This method, combined with an adsorption-elution method, yields a mean recovery of about 75%

A rapid method for quantitative assay of poliovirus from water with the aid of the fluorescent antibody technique.

A method is described for the rapid quantitative demonstration of polioviruses in water with the aid of the fluorescent antibody technique. Identification of the virus is possible after 18--24 hours as compared to 3--5 days required with the plaque count method. Approximately 10 plaque forming units, concentrated from a volume of 40 liters of seeded tap water could be demonstrated by the rapid method. Positive cells were already seen after 6--9 hours; the results were, however, not sufficiently quantitative. The method also showed itself to be less susceptible to bacterial contamination than the current isolation methods. Its possible utilization as a rapid, primary test for viral contamination of potable water is discussed.