Public Health Service study of Reye's syndrome and medications. Report of the main study

Between January 1985 and May 1986, following completion of a pilot study, a main study concerning the possible association between Reye's syndrome and salicylates was conducted. Twenty-seven patients with stage II or deeper Reye's syndrome whose diagnoses were confirmed by an expert panel and who had appropriate antecedent illnesses (chickenpox, respiratory illness, or gastrointestinal illness) prior to the onset of Reye's syndrome were compared with 140 controls matched for age, race (black or not black), and type and timing of onset of antecedent illness. Controls were selected from the same hospital, emergency room, or school as case-patients or were identified by random-digit telephone dialing. As in the pilot study, a strong statistical association with ingestion of salicylates during the antecedent illness and prior to the onset of Reye's syndrome was observed (odds ratio, 40; lower 95% confidence limit, 5.8). Analysis of the independent risk of aspirin and nonaspirin salicylates revealed a significant association with aspirin (odds ratio, 26; lower 95% confidence limit, 6.4); the independent risk of nonaspirin salicylates could not be assessed because only two cases were not exposed to aspirin. Assessment of epidemiologic issues of concern, including case-control differences in the severity of the antecedent illness, did not explain the high odds ratios that were observed. The high percentage of patients with Reye's syndrome exposed to salicylates (greater than or equal to 90%) in this and prior studies suggests that, though the reported incidence of Reye's syndrome has declined in recent years, concomitant with a decline in salicylate use among children, a majority of Reye's syndrome cases may be attributable to salicylate use.

Changing epidemiology of Reye syndrome in the United States

The average annual incidence of Reye syndrome reported through national surveillance was lower during 1981 to 1984 than during the previous five surveillance years. This is accounted for by a decrease in cases among children younger than 10 years of age; the number of cases in 10- to 19-year-old persons remained relatively stable during this period. The overall decline in incidence and the differing age-specific incidence trends are apparent for both varicella-associated cases and for nonvaricella-associated cases. During 1985, the incidence has been much lower than during any previous year since surveillance was initiated; this most recent decrease includes children 10 to 19 years of age. Independently conducted surveys suggest that the prevalence of salicylate use for viral illnesses has decreased among children in recent years, particularly among children younger than 10 years of age. The changing epidemiology of Reye syndrome may reflect, in part, the declining use of salicylates among children and teenagers in the United States.

Hemolytic-uremic syndrome--an outbreak in Sacramento, California

Between July and November 1982, 14 cases of the hemolytic-uremic syndrome occurred in the Sacramento, California, metropolitan area; 9 of the 14 patients lived within a 7.5-mile radius in northeast Sacramento, 10 were female, 12 were white non-Hispanic and 13 were children with a mean age of 3.6 years. Of the 14 patients, 13 were admitted to hospital; 7 required peritoneal dialysis. The 14th child, a 3-month-old white female infant, was found dead in her crib and had renal histopathologic findings consistent with the hemolytic-uremic syndrome. Of the 13 nonfatal cases, 12 patients had diarrhea before being admitted to hospital. A case-control study involving 11 cases and 22 controls did not show any significant differences in exposure to a variety of possible risk factors including restaurants, specific foods and water supply. Stool specimens were negative for enteric bacterial pathogens by culture and for viruses by tissue culture assay, suckling mouse inoculation and immune electron microscopy; no serologic evidence was found for infection due to enteroviruses, respiratory viruses or arenaviruses. Two of four children tested, however, showed serologic evidence of infection by Vero-cytotoxin-producing Escherichia coli. These 14 cases represent one of the largest reported outbreaks of the hemolytic-uremic syndrome in the United States.

A population-based study of hemolytic-uremic syndrome in Oregon, 1979-1982

The authors conducted a retrospective hospital-based chart review of cases of hemolytic-uremic syndrome among children less than or equal to 18 years of age, hospitalized in Oregon during the four-year period from January 1979 to December 1982. Thirty children with hemolytic-uremic syndrome living in Oregon were hospitalized during this period, for an average annual incidence of 0.97 cases per 100,000 children. Seventy per cent of cases occurred in children under five years of age, for an incidence of 2.65 cases per 100,000 children. Twenty-seven (90%) of the 30 children were white, and 17 (57%) were female. Twenty-four (80%) had a diarrheal prodromal illness including 20 who had bloody diarrhea. Twelve children (40%) acutely required peritoneal dialysis, and two (7%) developed chronic renal failure. Three children died, for a case fatality ratio of 10%. Sixty per cent of the 30 cases occurred during the summer and early fall months. Geographic clustering was also evident. Hemolytic-uremic syndrome is a rare but endemic disease in Oregon and may occur in small clusters. Although descriptions of several large series of patients have been published, this study describes the first statewide population-based study of this syndrome.

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 Reye's syndrome and medications. Thirty patients with Reye's 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 Reye's syndrome and the use of salicylates during an antecedent illness.

Kawasaki syndrome. Is exposure to rug shampoo important?

In the winter of 1982-1983, two clusters of cases of Kawasaki syndrome (KS) provided an opportunity to examine further the possible association among KS, antecedent illnesses, and carpet shampooing and related activities. The two clusters involved 16 patients with onsets between October and January, with seven cases occurring in two adjacent counties in New York (Herkimer and Oneida) and nine in Kent County, Michigan. None of the 11 children with KS included in a case-control study had been exposed to shampooed carpets during the month prior to the onset of KS. Only four (36%) of 11 children with KS, compared with 13 (59%) of 22 control subjects, reported a respiratory antecedent illness within 30 days prior to the onset of KS (odds ratio = 0.50, 95% confidence limits = 0.12 to 2.03). The previously observed associations of KS with antecedent respiratory illness and carpet shampooing remain unexplained and undocumented in these outbreaks.

National Reye syndrome surveillance, 1982

Despite the fact that influenza B was the primary influenza virus strain during the winter of 1981-1982, only 213 cases of Reye syndrome were reported to the Centers for Disease Control (CDC) between Dec 1, 1981 and Nov 30, 1982. This national reported incidence of 0.33 cases per 100,000 children less than 18 years of age is the lowest reported incidence since the Centers for Disease Control began surveillance in 1973. This relatively low incidence probably reflected, at least in part, the fact the influenza B activity was spotty and the illness relatively mild the winter of 1981-1982. The 213 cases were reported from 43 states; and in 56% of the patients, Reye syndrome occurred following a respiratory illness. The mean age of the children was 7.0 years; there were equal numbers of girls and boys; and 93% were white. Of the ten black patients, 80% were less than 1 year of age compared with 9% of the white patients. Of the 208 patients with reported admission stage, 45% were admitted in stage I or 0, a slightly lower proportion than that observed in the previous 2 years. Salicylate levels were obtained in 55% of the patients and were reported as "detectable" in 81% compared with 96% in 1981 (P = .003, chi 2). Of the 200 patients with known outcome, 70 patients died (a case fatality ratio of 35%).

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-Barré 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 less than 6, 6 to 16, 17 to 44, and greater than 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.

Surveillance for California encephalitis group virus illness in Wisconsin and Minnesota, 1978

During the summer and fall of 1978, active surveillance for encephalitis in southwestern Wisconsin and southeastern Minnesota resulted in the detection of the largest number of cases of California encephalitis group (CEG) virus infections ever documented in that region, where CEG virus is known to be endemic. A total of 75 laboratory-confirmed and eight presumptive cases of CEG virus infections were identified as a result of serologic testing completed in the Wisconsin and Minnesota State Laboratories. Cases included 46 residents of Wisconsin, 25 of Minnesota, 10 residents of Iowa and two from Illinois. The outbreak peaked during the last half of August and the first half of September. Eighty percent of patients were less than 10 years of age; only one case was documented in an adult (greater than or equal to 18 years). The clinical picture in patients ranged from mild aseptic meningitis to encephalitis with coma; convulsions occurred in 31% (22/72) of patients. One patient, a 3-year-old girl, died. The high incidence of infection detected in this investigation may be representative of the endemic incidence of CEG illness in the region and suggests that CEG infections in children residing in endemic areas in Wisconsin and Minnesota may be a greater public health problem than previously recognized.

Kawasaki syndrome in the United States 1976 to 1980

Review of 523 confirmed cases of Kawasaki syndrome reported to the Centers for Disease Control (CDC), during the period from July 1976 through December 1980, disclosed a previously unrecognized seasonal variation, with a peak incidence between February and May. A significantly higher incidence in black children, compared with white children, was also noted. Earlier reports of a higher incidence in children younger than 5 years of age, males, and children of Asian ancestry were confirmed. Frequently reported complications included joint involvement (27%) and cardiac abnormalities (22%); 1.2% of patients died. Four outbreaks (mean duration, 3.8 months) were investigated by the CDC, but no evidence of person-to-person transmission or a point source of exposure was found. These data suggest that some cases may be caused by an exogenous agent or toxin that is most prevalent in the late winter and spring. In addition, host, environmental, or other cofactors are likely to be important determinants of susceptibility.

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.

National surveillance for Reye syndrome: a five-year review

National surveillance for Reye syndrome conducted during five years, including the period 1973-1974 and December 1976 through November 1980, has resulted in the reporting of more than 2,000 cases of Reye syndrome. The highest reported incidence of Reye syndrome occurred during years of primary influenza B and A (H1N1) activity; the reported incidence during one period of influenza A (H3N2) activity was somewhat lower. Regional outbreaks of Reye syndrome have been associated with influenza A (H1N1) and B but now with influenza A (H3N2). Cases of Reye syndrome in whites tend to be distributed throughout all age groups whereas a large percentage of cases in blacks have been reported in infants less than 1 year of age in three of the past four years. Nationally, there has been a decline in the case-fatality ratio in recent years.

A cluster of cases of Reye syndrome associated with chickenpox

In the spring of 1980, four confirmed, and three possible cases of Reye syndrome, each associated with a chickenpox prodromal illness, were identified in Las Cruces, NM. One patient, a 5-year-old girl, died. Cases tended to occur in one section of the community, among children attending two of the 16 elementary schools. A telephone survey of parents with school-aged children (6 to 9 years old) suggested that a significantly greater attack rate of chickenpox occurred in children attending those two schools. Based upon this survey and the expected distribution of chickenpox among children less than 15 years of age, the incidence of Reye syndrome following chickenpox infection in the county in which Las Cruces is located was estimated to be 2.5/10,000 cases of chickenpox; these data reveal a four- to ninefold greater incidence of Reye syndrome than that following influenza B infections, which was previously estimated based upon a cluster of five cases in a county in Michigan. Additional investigations of Reye syndrome clusters are needed in an effort to identify and study suspected risk factors and to better define the relationship between Reye syndrome and viral infections.

Reye's syndrome and medication use

Ninety-seven Reye's syndrome (RS) cases in Ohio children with onsets from December 1978 through March 1980 were studied for medication use during their pre-RS illness. They were matched with 156 control subjects for age, race, sex, geographic location, time, and type of illness. Only the use of aspirin was reported by significantly more cases (97%, 94/97) than controls (71%, 110/156) during the pre-RS matched illness. Using a multiple logistic model to control for the presence of fever, headache, and sore throat statistically, the difference in aspirin use remained significant. Conversely, fewer cases (16%) took medications containing acetaminophen than controls (33%). In 87% of the cases receiving aspirin, their maximum daily dosage did not exceed recommended levels, but their doses were higher than those of controls receiving aspirin. No relationship was found between dosage and stage of RS encephalopathy.

Guillain-Barré syndrome in the United States, 1979-1980 and 1980-1981. Lack of an association with influenza vaccination

An ongoing surveillance program was intensified during the 1979-1980 and the 1980-1981 influenza seasons to determine whether an increased risk of acquiring Guillain-Barré syndrome (GBS) within eight weeks after influenza vaccination existed for adults in the United States who received influenza vaccine, when compared with adult who had not been vaccinated recently. Five hundred twenty-eight cases of GBS with onset between Sept 1 and March 31, including seven following recent vaccination, were reported by participating neurologists in 1979-1980; 459 cases, including 12 following recent vaccination, were reported in 1980-1981. The relative risk of acquiring GBS following influenza vaccination--0.6 in 1979-1980 and 1.4 in 1980-1981--was not significantly different from 1.0 in either season. These results suggest that there was no increased risk of acquiring GBS associated with the influenza vaccines administered during these seasons and that the causative "trigger agent" in the A/New Jersey (swine) influenza vaccine administered in 1976 has not been present in subsequent influenza vaccine preparations.

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.

Resistance of Plasmodium falciparum malaria to sulfadoxine-pyrimethamine ('Fansidar') in a refugee camp in Thailand

Since it was first introduced 'Fansidar' (pyrimethamine 25 mg, sulfadoxine 500 mg) has been the preferred treatment for uncomplicated chloroquine-resistant Plasmodium falciparum malaria in Thailand. Because many patients at a refugee camp in Thailand did not seem to be responding to therapy 9 patients who received fansidar for P. falciparum infection were followed up with serial parasite counts. In all of them the infection was resistant to fansidar. The results of this study suggest that fansidar resistance is prevalent at this camp and should prompt more exhaustive studies of the epidemiology of fansidar resistance in the area.

Guillain-Barré syndrome: its epidemiology and associations with influenza vaccination

The epidemiology of Guillain-Barré syndrome (GBS) and the associations of GBS with influenza vaccination are described based on review of three types of epidemiological data: case-control studies, incidence rate studies of GBS in well-defined populations, and surveillance data from a sentinel neurologist surveillance system of GBS in the United States. These data indicate that the crude annual incidence rate of GBS per 100,000 people ranges from 0.6 to 1.9 in different populations in widely scattered areas of the world. In general, incidence rates are higher with advancing age until about 75 years, higher for men than women, and higher for whites than blacks. No specific HLA antigen has been significantly associated with GBS in general, although HLA AW 30 and AW 31 have been associated with chronic relapsing polyneuritis. Important trigger agents of GBS include nonspecific respiratory and gastrointestinal infections and cytomegalovirus infection. Influenza infection and influenza vaccinations are not generally important trigger agents. A major exception to this is the occurrence of just under 1 excess case of GBS per 100,000 A/New Jersey influenza vaccinations administered in the United States, 1976-1977. A significant excess risk of GBS was not observed after administration of influenza vaccine in 1978-1979 and 1979-1980. The differences between the contents of and immunological reaction to A/New Jersey influenza vaccine and the more recent influenza vaccines deserve further study.

An epidemic of Reye syndrome associated with influenza A (H1N1) in Colorado

An unusual cluster of Reye syndrome was associated with an outbreak of influenza A (H1N1) infections in the state of Colorado. Two of the 16 affected children had had prior episodes of Reye syndrome following respiratory infections, and one had had transverse myelitis following varicella. A serologic study of patients treated at a children's hospital and serum specimens submitted to the state health department revealed that approximately 59% of children in Colorado had been infected with the H1N1 strain of influenza A over a two-year period. Based upon this serologic survey, the minimum and maximum rates of Reye syndrome associated with H1N1 infections were calculated to be 2.5 and 4.3 cases per 100,000 H1N1 infections, respectively. A retrospective analysis of admissions to four referral hospitals in Denver failed to reveal any unusual clustering of Reye syndrome with outbreaks of influenza A H3N2 infections during 1975-1978. The reason for an association between Reye syndrome and the H1N1 strain but not the H3N2 strains of influenza A remains unclear.

National surveillance of Kawasaki disease

Information about 261 cases of Kawasaki disease (KD) was reported to the Center for Disease Control (CDC) between July 1976 and July 1978. KD occurred at all times of the year in young, previously healthy children throughout the United States. KD was more common in infants and toddlers, males, and Asian and part-Asian children. The illness was characterized by acute onset of prolonged high fever; maculopapular or scarlatiniform rash; adenopathy; injection of the conjunctival and mucous membranes of the upper respiratory tract; redness of the palms and soles; indurative edema of the extremities; desquamation, arthralgias; and elevated white blood cell count, erythrocyte sedimentation rate, and platelet count. Complications included gallbladder disease and carditis; 2.8% died. Surviving patients were hospitalized for a mean of 8.9 days.