Biomedical subjects
S H Waterman
Publications and source records attributed to S H Waterman.
Meningococcal disease in Los Angeles County, 1981 through 1990.
Explore the source record for details and available documents.
A suburban focus of endemic typhus in Los Angeles County: association with seropositive domestic cats and opossums.
Thirty-three cases of locally acquired murine typhus were reported in Los Angeles County residents from May 1984 through February 1988. Only eight cases were reported over the previous 20-year period. Thirty (91%) cases resided within a suburban area encompassing approximately 50 km2 in northcentral Los Angeles or had contact with an animal from this area. Serologic testing (complement fixation and indirect fluorescent antibody) of selected animals in close association with human cases revealed a high prevalence of seropositivity among domestic cats and opossums. Nine (90%) of 10 resident cats tested had demonstrable antibody titers compared with none (0%) of 20 cats from a control area (P < 0.001). Suburban typhus cases were more likely than neighborhood controls to own a cat or dog (odds ratio = 6.9, 95% confidence interval = 1.8, 25.9, P = 0.002). Sixteen (42%) of 38 opossums trapped in close proximity to the residences of cases were seropositive versus none (0%) of 36 opossums from control areas (P < 0.001) A low frequency (2.8%) of seropositivity was found in commensal rodents, and the classic vector of murine typhus, Xenopsylla cheopis, was not found. Ectoparasite indices form seropositive opossums revealed heavy infestations with the cat flea, Ctenocephalides felis (mean flea count = 104.7), a species that readily bites humans. These data provide evidence that a suburban focus of murine typhus exists in Los Angeles that differs substantially from the classic transmission cycle, and that cats, opossums and C. felis may play an important role in the occurrence of human cases.
Measles epidemic from failure to immunize.
During 1988 through 1990, California experienced its worst measles epidemic in more than a decade, with 16,400 reported cases, 3,390 hospital admissions, and 75 deaths. More than half of the patients were younger than 5 years; the highest incidence was among infants younger than 12 months. The epidemic centered in low-income Hispanic communities in southern and central California. The major cause of the epidemic was low immunization levels among preschool-aged children and young adults. Rates of complications, admission to hospital, and death were surprisingly high. Outbreak control efforts met with indeterminate success. Problems with these efforts included insufficient funding early in the epidemic and disappointing public response to community-based immunization campaigns. The cost of medical care and outbreak control for the epidemic is conservatively estimated at $30.9 million. Unless the level of immunization in preschool-aged children is increased, this type of epidemic will probably recur.
Risk factors for invasive Haemophilus influenzae type b in Los Angeles County children 18-60 months of age.
Potential factors that confer risk or protection for invasive Haemophilus influenzae type b disease were evaluated in Los Angeles County children 18-60 months of age by case-control methods. In this age group, 79 H. influenzae type b cases were identified by overlapping surveillance methods, and 221 random controls were selected by random digit dialing. Cases and controls were similar in sex, prior health, proportion attending day care, parental educational level, history of breast feeding, and proportion vaccinated with measles/mumps/rubella vaccine. The effect of H. influenzae type b vaccination was controlled in all analyses, and results of vaccine efficacy have been reported elsewhere. Cases were more likely to have a significant underlying medical condition, reside in home with more than six residents, have a lower yearly household income, have two or more smokers in the home, and to be black. Using conditional logistic regression models, the following were significant independent risk factors after adjusting for age, month of diagnosis, H. influenzae type b vaccine status, and the other factors: 1) more than two smokers in the house (odds ratio (OR) = 6.00; 95% confidence interval (CI) 1.49-24.06); 2) household size of more than six persons (OR for more than six vs. less than three persons = 3.71; 95% CI 1.10-12.60); and 3) black maternal race (OR for black vs. Hispanic = 3.47; 95% CI 1.41-8.53). We conclude that exposure to smoking in the home, living in households with more than six members, and the black race are each independently associated with an increased risk for H. influenzae type b disease in Los Angeles County children and, when combined, constitute a major reason for H. influenzae type b disease occurrence.
Characterization of Neisseria meningitidis serogroup C by multilocus enzyme electrophoresis and ribosomal DNA restriction profiles (ribotyping).
We compared multilocus enzyme electrophoresis (MEE) and ribosomal DNA fingerprinting (ribotyping) for subtyping 44 strains of Neisseria meningitidis serogroup C that were isolated in Los Angeles County, California, between December 1985 and July 1986. The isolates were divided into six enzyme types (ETs) by MEE, but 36 of the isolates were clustered in one ET, 3. The same isolates were divided into 17 ribotypes by use of restriction endonucleases ClaI, EcoRI, and XhoI. Twenty of the 36 ET 3 isolates were divided into 17 ribotypes by use of restriction endonucleases ClaI, EcoRI, and XhoI. Twenty of the 36 ET 3 isolates were grouped in a single ribotype, J. The rate of infection with ribotype J strains was higher in the southern part of the study area than in the northern part. Isolates from each of eight pairs (each isolate pair was cultured from the same patient from the same or different sites) were found identical by MEE, but ribotyping revealed a difference in one pair. In this study, ribotyping showed a greater discriminating capacity than MEE for subtyping N. meningitidis serogroup C, but the epidemiologic relevance of this increased sensitivity needs further assessment.
Cysticercosis surveillance: locally acquired and travel-related infections and detection of intestinal tapeworm carriers in Los Angeles County.
A surveillance system for cysticercosis was initiated in January 1988 in Los Angeles County to measure the incidence of the disease, to more accurately assess the level of locally acquired and travel-related infection, and to evaluate household contacts for intestinal tapeworm infection. In three years of surveillance (1988-1990), 138 incident cases were reported for an average crude annual incidence rate of 0.6 per 100,000 population. The highest rates were among Hispanics (1.6/100,000), most of whom were Mexican immigrants. Eight (5.8%) cases were fatal. Nine (6.5%) probable travel-associated cases occurred among persons born in the United States who had traveled to Mexico. Ten (7.2%) autochthonous cases of cysticercosis were documented. Taenia eggs were recovered more commonly in specimens from contacts with cysticercosis cases (1.1%) than in specimens from noncontact patients (0.2%). At least one Taenia tapeworm carrier was found among contacts of five (6.9%) of 72 cysticercosis patients. Carriers were more likely to be found among contacts of patients born in the United States (22.2%) than among those of foreign-born (4.8%) patients (odds ratio = 5.4) Cysticercosis causes appreciable morbidity and mortality in Los Angeles County, principally among Hispanic immigrants. However, these results indicate that both travel-acquired and locally acquired cysticercosis may be more common than previously recognized. Public health followup of cysticercosis cases, including screening of household contacts, can identify tapeworm carriers, who can be treated and removed as potential sources of further infection.
Protective efficacy of Haemophilus influenzae type b polysaccharide and conjugate vaccines in children 18 months of age and older.
To evaluate the protective efficacy of polyribosylribitol phosphate (PRP) and polyribosylribitol phosphate-diphtheria toxoid (PRP-D) vaccines in children 18 to 59 months of age, we conducted a case-control study in Los Angeles (Calif) County between July 1, 1988, and July 31, 1989. Seventy-nine children with invasive Haemophilus influenzae type b disease 18 to 59 months of age were identified, and 212 controls were selected by random-digit telephone dialing methods. Cases and controls were stratified by age and month of disease onset of the case. Seventeen PRP vaccine failures and two PRP-D vaccine failures occurred more than 2 weeks after vaccination. The PRP vaccine was shown not to be effective (point estimate--47%; 95% confidence interval,--307% to 47%), but the PRP-D vaccine was 88% protective (95% confidence interval, 42% to 97%). Adjustment of the efficacy estimates for potential confounding variables did not change the results significantly. The PRP-D vaccine provided significantly better protection than the PRP vaccine against invasive H influenzae type b disease in this population.
Risk factors for carriage of meningococcus in the Los Angeles County men's jail system.
Ten cases of meningococcal meningitis in the Los Angeles County men's jail system in 1986 were the first known reported cases in this population. New cases have continued into 1990. Nineteen of 21 symptomatic cases identified by serogroup from the men's jail occurring through 1988 had serogroup C. The prevalence of meningococcal carriage and potential risk factors were studied in 1988 among 150 men booked to enter the jail, 350 inmates being released, and 100 jail staff. The prevalence of meningococcal carriage among releases, bookings, and staff were 25.4%, 18.7%, and 5.0%, respectively. Among releases, imprisonment longer than a threshold of 28 days increased carriage of serogroup C 10.0 times (95% confidence interval (CI) 4.6-21.6). Among bookings, household crowding increased serogroup C carriage 8.2 times (95% CI 1.5-45.3). Direct and passive smoking at home increased carriage of any serogroup 5.2 (95% CI 1.2-47.5) and 2.5 (95% CI 1.1-5.8) times, respectively. Feasible potential interventions include banning smoking in the jail and immunization with quadrivalent meningococcal vaccine of booked men sentenced for one month or more.
Meningococcal disease in the United States--1986. Meningococcal Disease Study Group.
Active surveillance for invasive meningococcal disease was conducted during 1986 and 1987 in six areas of the United States with a total population of approximately 34 million persons. The incidence of meningococcal disease was 1.3:10(5). The highest incidence of disease among the surveillance areas was in Los Angeles County (1.65:10(5). Neisseria meningitidis serogroups B and C caused about equal amounts of disease, which reflects a recent increase in the incidence of group C disease. Group C caused more than half of the cases of meningococcal disease in Los Angeles and Tennessee but less than one-third of the cases in Missouri and Oklahoma. Multilocus enzyme electrophoresis demonstrated that a group of closely related isolates of N. meningitidis was prevalent in Los Angeles during the surveillance period and was associated with an increased incidence of meningococcal disease there.
Measles vaccination coverage among Latino children aged 12 to 59 months in Los Angeles County: a household survey.
A high rate of measles transmission has occurred in Los Angeles County since 1987. To determine measles vaccination coverage among Latino preschoolers, the group at highest risk of measles during this period, a cluster survey was conducted among Latino households with children aged 12 to 59 months. Of 279 children enrolled, 240 (86%, 95% confidence interval = 81% to 91%) reportedly had received the measles vaccine. Measles vaccination coverage among Latino preschoolers in Los Angeles County is insufficient to halt measles transmission within this subpopulation.
Incidence of campylobacteriosis among patients with AIDS in Los Angeles County.
The incidence and characteristics of campylobacteriosis among patients with acquired immune deficiency syndrome (AIDS) in Los Angeles County were assessed by matching the Campylobacter and AIDS surveillance reporting registries for the years 1983-1987. Campylobacter infection was reported in 29 (0.7%) of 4,433 AIDS cases. The average annual incidence of Campylobacter among AIDS cases (519/100,000) exceeded the crude population rate by 39-fold and exceeded the rate among males aged 15-55 years by 35-fold. Campylobacter infection was more common in female AIDS patients than male patients (p = 0.065). A distinct seasonal variation was noted with peaks occurring in July and November. The median survival time for AIDS patients with Campylobacter (14 months) was lower than that for AIDS patients without Campylobacter (21 months); however, we were not able to assess potential confounders such as subsequent opportunistic infections or antiviral therapy and prophylactic regiment to validate this finding. Campylobacter cases with AIDS had higher rates of bacteremia and hospitalization than Campylobacter cases without AIDS. Attempts should be made to elucidate the sources of Campylobacter and other enteric infections among AIDS patients.
Isospora belli and the acquired immunodeficiency syndrome.
Explore the source record for details and available documents.
An outbreak of acute gastroenteritis caused by a small round structured virus in a geriatric convalescent facility.
An outbreak of acute gastroenteritis (AGE) occurred in a 201-bed geriatric convalescent facility in Los Angeles County during December 1988 through January 1989. The attack rate was 55% among residents and 25% among employees. Illnesses were characterized by vomiting and diarrhea to a lesser extent, and the absence of fever. Bacterial and parasitic tests in a sample of patients were negative. A 27 nm small round structured virus (SRSV) was identified in one of 30 stools studied by immune electron microscopy (IEM). While rotavirus and influenza A and B were found in three, one and three cases, respectively, no alternative etiologic agent could be demonstrated for most cases. The outbreak met Centers for Disease Control (CDC) clinical and epidemiologic criteria for Norwalk-like gastroenteritis. The death rate of residents was not elevated beyond baseline during the outbreak; however, one healthy employee had diarrhea and dehydration and died after developing an arrhythmia. An autopsy showed moderate, diffuse lymphocytic and neutrophilic myocarditis, and viral studies found influenza A in left ventricular tissue. Fourteen (25%) of 57 employee cases worked in occupations without routine stool or patient contact. At least nine of these employees lacked evidence of direct fecal contact, and transmission of infection in these cases may have been airborne.
Salmonella arizona infections in Latinos associated with rattlesnake folk medicine.
In 1987 two Los Angeles County (California) hospitals reported four Latino patients with serious Salmonella arizona (Salmonella subgroup 3) infections who gave a medical history of taking rattlesnake capsules prior to illness. Capsules supplied by the patients or household members grew Salmonella arizona. We reviewed surveillance data for this Salmonella species and conducted a case-control study to determine the magnitude of this public health problem. Eighteen (82 percent) of the 22 Latino cases in 1986 and 1987 who were questioned reported ingesting snake capsules compared to two (8 percent) of 24 matched Latino controls with non-subgroup 3 salmonellosis or shigellosis (matched pair odds ratio = 18.0, CI = 4.2, 76.3). An average of 18 cases per year of Salmonella arizona were reported in the county between 1980 and 1987. In this investigation the majority of S. arizona cases reporting snake capsule ingestion had underlying illnesses such as acquired immunodeficiency syndrome (AIDS), diabetes, arthritis, cancer. The capsules were obtained primarily from Tijuana, Mexico and from Los Angeles, California pharmacies in Latino neighborhoods. Despite publicity and attempts to remove the capsules from sale in California, Salmonella arizona cases associated with snake-capsule ingestion continue to occur.
Occupational exposure to influenza--introduction of an index case to a hospital.
The epidemiology of influenza in the hospital is frequently confounded by failure to separate community-acquired from nosocomial transmission. An 83-year-old woman was hospitalized one day after returning from Asia with complications resulting from acute influenza A (H3N2) infection; she was the first culture-confirmed case in the region during the 1987-1988 influenza season, and her illness antedated other influenza cases in the area by at least four weeks. The patient shed virus at least four days after admission and transmitted influenza to her primary physician; both had received trivalent influenza vaccine four weeks earlier. Surveillance data from the 28 health care providers (HCPs) in contact with the index case (mean age: 34.5 years; median time of contact: four hours, none receiving vaccine) revealed no evidence of transmission as detected by paired type-specific complement-fixation antibodies and throat culture (20 subjects) or acute serologies and culture (7 subjects). No febrile respiratory illnesses were detected among other patients on the same ward, although three were reported among HCPs. Thus, neither secondary spread of influenza from infected patient to hospital HCPs nor nosocomial transmission apparently took place, although transmission did occur to the primary physician.
Community-acquired group A streptococcal deaths in Los Angeles County.
Explore the source record for details and available documents.
Declining rates of amebiasis in Los Angeles County: a sentinel for decreasing acquired immunodeficiency syndrome (AIDS) incidence?
In Los Angeles County from 1983-1988, rates of amebiasis declined 65 percent among White males 15-44 years. No such decline occurred among White females 15-44 years or White males less than 15. Reported acquired immunodeficiency syndrome (AIDS) cases in the district of highest AIDS incidence has followed the initial decline in amebiasis by four years. Amebiasis trends may be a useful predictor of human immunodeficiency virus (HIV) transmission and future rates of AIDS among gay men.