Eugene S. Hurwitz

Large community outbreak of cryptosporidiosis due to contamination of a filtered public water supply.

Between January 12 and February 7, 1987, an outbreak of gastroenteritis affected an estimated 13,000 people in a county of 64,900 residents in western Georgia. Cryptosporidium oocysts were identified in the stools of 58 of 147 patients with gastroenteritis (39 percent) tested during the outbreak. Studies for bacterial, viral, and other parasitic pathogens failed to implicate any other agent. In a random telephone survey, 299 of 489 household members exposed to the public water supply (61 percent) reported gastrointestinal illness, as compared with 64 of 322 (20 percent) who were not exposed (relative risk, 3.1; 95 percent confidence interval, 2.4 to 3.9). The prevalence of IgG to cryptosporidium was significantly higher among exposed respondents to the survey who had become ill than among nonresident controls. Cryptosporidium oocysts were identified in samples of treated public water with use of a monoclonal-antibody test. Although the sand-filtered and chlorinated water system met all regulatory-agency quality standards, sub-optimal flocculation and filtration probably allowed the parasite to pass into the drinking-water supply. Low-level cryptosporidium infection in cattle in the watershed and a sewage overflow were considered as possible contributors to the contamination of the surface-water supply. We conclude that current standards for the treatment of public water supplies may not prevent the contamination of drinking water by cryptosporidium, with consequent outbreaks of cryptosporidiosis.

Immunogenicity of Hepatitis B Vaccines Implications for Persons at Occupational Risk of Hepatitis B Virus Infection

OBJECTIVE To assess risk factors for decreased immunogenicity among adults vaccinated with hepatitis B vaccine and to determine the importance of differences in immunogenicity between vaccines among health care workers (HCWs). DESIGN Randomized clinical trial and decision analysis. PARTICIPANTS HCSw. MAIN OUTCOME MEASURES Development of seroprotective levels of antibody to hepatitis B surface antigen (anti-HBs) and the number of expected chronic hepatitis B virus (HBV) infections associated with lack of protection. RESULTS Overall, 88% of HCWs developed seroprotection. Risk factors associated with failure to develop seroprotection included increasing age, obesity, smoking and male gender (P < .05). Presence of a chronic disease was associated with lack of seroprotection only among persons > or = 40 years of age (P < .05). The two vaccines studied differed in their overall seroprotection rates (90% vs. 86%; P < .05), however, this difference was restricted to persons > or = 40 years of age (87% vs. 81%; P < .01). Among HCWs > or = 40 years of age, the decision analysis found 44 (0.34/100,000 person-years) excess chronic HBV infections over the working life of the cohort associated with use of the less immunogenic vaccine compared to the other. CONCLUSIONS He patitis B vaccines are highly immunogenic, but have decreased immunogenicity associated with increasing age, obesity, smoking, and male gender; and among older adults, the presence of a chronic disease. One of the two available vaccines is more immunogenic among older adults; however, this finding has little clinical or public health importance. Hepatitis B vaccines should be administered to persons at occupational risk for HBV infection early in their career, preferably while they are still in their training.

Guillain-Barré Syndrome and the 1978–1979 Influenza Vaccine

An ongoing surveillance program was intensified to determine whether an increased risk of acquiring vaccine-related Guillain-Barré syndrome (GBS) (similar to that observed after vaccination with the A/New Jersey swine-influenza vaccine in 1976) existed for the approximately 12.5 million adults (greater than or equal to 18 years old) vaccinated in the 1978-1979 influenza campaign. In the contiguous United States (excluding Maryland) 544 cases of GBS with onset between September 1, 1978, and March 31, 1979, were reported, including 12 adults who had been vaccinated within eight weeks before the onset of GBS and 393 who had not. The relative risk of vaccine-associated GBS for adults reported in this surveillance was 1.4 (95% confidence limits, 0.7 to 2.7)--significantly below the risk (6.2) associated with A/New Jersey vaccine for the equivalent eight-week period. In contrast to the A/New Jersey vaccine, the 1978-1979 influenza vaccine was not associated with a statistically significant excess risk of GBS.

Studies of the 1996–1997 Inactivated Influenza Vaccine among Children Attending Day Care: Immunologic Response, Protection against Infection, and Clinical Effectiveness

A randomized, blinded, pilot study of influenza vaccine administered to children attending day care centers was conducted during the 1996-1997 winter. Vaccine efficacy in preventing serologically proven influenza virus infection was 0.45 (95% confidence limit [CL]: -0.02, 0.69) for influenza B and 0.31 (95% CL: -0.95, 0.73) for influenza A(H3N2). For both influenza A(H3N2) and B, children without preexisting hemagglutination inhibition (HI) antibody to these antigens had lower antibody responses to vaccine, were less likely to develop a serological response, and were more likely to develop serological evidence of influenza infection. Although there were no reductions in respiratory or febrile respiratory illnesses among all vaccinated children, there was a trend for reductions in such illnesses among vaccinated children with preexisting HI antibodies to influenza A(H3N2) and B. Therefore, immunologic priming in young children may be important for vaccine response and for protection against infection. Larger studies are needed in other influenza seasons to assess vaccine efficacy and clinical effectiveness.

Public Health Service Study on Reye's Syndrome and Medications Report of the Pilot Phase

Between February and May 1984, we conducted a pilot study to examine the methods for a larger study of a previously reported relation between Reyes syndrome and medications. Thirty patients with Reyes syndrome, whose diagnosis was confirmed by an expert panel, and 145 controls were matched for age, race (black or not black), and antecedent illness (respiratory infection, chickenpox, or diarrhea) and selected from the same hospital, emergency room, or school, or identified by random digit dialing. Significantly more cases (93 per cent, 28 of 30) than members of each of the four control groups or all controls combined (46 per cent, 66 of 145) had received salicylates during matched antecedent illnesses (odds ratio of all 30 cases vs. all controls = 16.1; lower 95 per cent confidence limit = 4.6). The prevalence and mean severity score of signs, symptoms, and selected events during the antecedent illness tended to be lower among cases than controls. Thus, differences in the severity of this illness between cases and controls did not explain differences in medication exposures. This pilot study suggests an association between Reyes syndrome and the use of salicylates during an antecedent illness.

Guillain‐Barré syndrome in the United States, 1978–1981 Additional observations from the national surveillance system

During the period January 1978-March 1981, 2,575 cases of Guillain-Barre syndrome (GBS) were reported by participating neurologists in the national GBS surveillance system. The incidence of GBS was highest in the 50- to 74-year-old age group, but a lesser peak was observed in persons aged 15 to 35. The frequencies of antecedent respiratory (43%) and gastrointestinal (21%) illness exceeded frequencies of such illnesses in the US population (10 and 0.8%, respectively), based on survey data compiled by the National Center for Health Statistics; the differences in these frequencies of illness were similar in all seasons of the year, in males and in females, and in persons < 6, 6 to 16, 17 to 44, and > 44 years of age. Nineteen percent of adult patients for whom information was available (67% of the total) reported receiving an A/ New Jersey influenza vaccine in 1976, a lower percentage than would be expected on the basis of a survey conducted in that year. The data suggest that persons who received this vaccine have not been at increased risk and may even have been at decreased risk of acquiring GBS during the period covered by this study.

National surveillance for Guillain‐Barré syndrome January 1978‐March 1979

Between January 1, 1978, and March 31, 1979, 1,034 cases of Guillain-Barré syndrome (GBS) were reported to the Centers for Disease Control by the 1,813 American Academy of Neurology sentinel physicians who participated in the national GBS surveillance program. A direct correlation was observed between increasing age and the age-specific attack (incidence) rates. Based on the cases observed and the total US population, age-adjusted attack rates were statistically higher in males (0.52 per 100,000) than in females (0.40). Rates for whites were 0.44 and those for blacks 0.28 per 100,000; although the difference is statistically significant, uncertainties as to the true denominators by race preclude acceptance of these differences as valid. Sixty-seven percent, or 682 of the patients, reported that they had had an antecedent illness within 8 weeks before onset of GBS, and among them the peak period of onset of GBS was in the second week after the onset of the prior illness. There were also 52 patients (5%) who had undergone surgery and 45 (4.5%) who had received vaccinations, both within the 8 weeks before onset of GBS. However, the high proportions of antecedent illness in these groups (45% of those operated and 53% of those vaccinated) made attribution of GBS to the procedures tenuous. Risk of GBS in patients who reported receiving a swine influenza vaccination in 1976 was no greater than in those who reported that they did not receive this vaccine.

Results of the national surveillance for Guillain‐Barré syndrome

The preliminary results of the national surveillance for Guillain-Barré syndrome (GBS) are reported. In the first 6 months of 1978, 327 cases of GBS were reported to the Center for Disease Control (CDC). A statistically significant difference was observed between sex-specific attack rates, and a direct correlation also was observed between advancing age and increasing risk of GBS.

AN OUTBREAK OF HEMOLYTIC-UREMIC SYNDROME IN SACRAMENTO, CALIFORNIA

Between July and November 1982, 14 cases of hemolyticuremic syndrome (HUS) occurred in the Sacramento, California, metropolitan area. In the 42-month period prior to July 1982, only 4 cases could be identified by a retrospective review of discharge diagnoses in Sacramento area hospitals. Nine patients lived within a 7.5-mile radius in northeast Sacramento. Ten patients were female, 12 were white, and 13 were children (mean age 3.6 years). Thirteen of the 14 patients were hospitalized, seven required peritoneal dialysis, and one died. Twelve of the 13 survivors had diarrhea prior to hospitalization. A case-control study, involving 11 cases and 22 controls matched for age, sex, race, and primary-care physician, did not reveal any significant differences in exposure to a variety of possible risk factors including restaurants, specific foods, and water supply. Although HUS has occurred in association with enteroviruses, Salmonella, Campylobacter, Yersinia, and Shigella, we were unable to isolate any of these organisms from the stool specimens of 5 patients during the acute illness. In addition, a recent report has suggested that Vero-toxin producing E. coli may be associated with HUS; we were also unable to islolate these organisms. Examination of stools for presence of the toxin and serum for presence of antibody to the toxin are pending.

Association Between Salicylates and Reye's Syndrome-Reply

In Reply.— Soller and Stander, on the basis of an unpublished analysis of our data, raise the issue of two potential biases: protopathic and product confusion bias. The existence of protopathic bias, or bias caused by the disease preceding the risk factor, depends on how the onset of RS is defined. We defined the onset of RS as the first day of severe vomiting. In the second year of our study, aspirin was classified as a positive exposure for cases only if ingested before the first day of severe vomiting. Thus, this bias regarding the temporal association of aspirin and RS should not be a problem if the onset of vomiting properly identifies the onset of RS. Even if clinical RS can precede severe vomiting, a retrospective determination of the exact onset on the basis of a complex of nonspecific symptoms, eg, headache, fever, or sore throat, symptoms all compatible