Yield of source-case and contact investigations in identifying previously undiagnosed childhood tuberculosis

OBJECTIVE

To determine the extent to which source-case investigations, in which a child was the index tuberculosis (TB) case, and contact investigations of adult pulmonary cases, identified children and adults with previously undiagnosed TB or latent tuberculosis infection (LTBI).

METHODS

We reviewed records of 111 source-case investigations and 38 contact investigations involving 164 TB cases among children <5 years of age from eight California health jurisdictions with a case rate greater than the state average for this age group (9.6/100000).

RESULTS

In source-case investigations, 141 children <5 years and 113 children 5-14 years of age were evaluated for TB disease and LTBI. Fourteen previously undiagnosed TB cases were found, including seven children <5 years of age. Source-case investigations also identified persons who might benefit from treatment for LTBI (45% had a positive tuberculin reaction). In contact investigations of adult TB cases, 202 children <5 years and 122 children 5-14 years of age were evaluated. In addition to 46 children with TB <5 years of age, the basis on which these contact investigations were selected for study, four children 5-14 years of age and 10 adults were found to have TB disease. A high percentage (41%) of contacts with a positive tuberculin reaction was found, especially among household contacts.

CONCLUSIONS

Source-case investigations and contact investigations are effective for finding previously undiagnosed cases of TB. They are also useful for identifying children and adults who would possibly benefit from treatment for LTBI. Earlier detection and treatment of adults with TB could interrupt transmission and be a step toward eliminating childhood TB.

Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chlorine

Raw sprouts have been implicated in a number of foodborne disease outbreaks. Because contaminated seeds are usually responsible, many sprout producers attempt to disinfect seeds before germination and detect sprout contamination during production. In March 2001, we detected an increased number of Salmonella serotype Kottbus isolates in California. Overall, we identified 31 cases from three western states. To identify the cause, we conducted a case-control study with the first 10 identified case-patients matched to 20 controls by age, sex, and residential area. Our case-control study found illness to be statistically associated with alfalfa sprout consumption. The traceback investigation implicated a single sprouter, where environmental studies yielded Salmonella Kottbus from ungerminated seeds and floor drains within the production facility. Pulsed-field gel electrophoresis patterns of all patient, seed, and floor drain Salmonella Kottbus isolates were indistinguishable. Most implicated sprouts were from seeds that underwent heat treatment and soaking with a 2,000-ppm sodium hypochlorite solution rather than the Food and Drug Administration (FDA)-recommended 20,000-ppm calcium hypochlorite soak. Other implicated seeds had been soaked in a calcium hypochlorite solution that, when tested, measured only 11,000 ppm. The outbreak might have been averted when screening tests of sprout irrigation water detected Salmonella in January; however, confirmatory testing of these samples was negative (but testing improperly utilized refrigerated irrigation water). Producers should use the enrichment broth of positive screening samples, not refrigerated irrigation water, for confirmatory testing. Until other effective disinfection technologies are developed, producers should adhere to FDA recommendations for sprout seed disinfection.

Escherichia coli O157 and Salmonella infections associated with sprouts in California, 1996-1998

BACKGROUND

In California, from 1996 through 1998, more than 50% of multicounty outbreaks with confirmed food vehicles were related to alfalfa or clover sprouts.

OBJECTIVE

To summarize investigations of sprout-associated outbreaks.

DESIGN

Matched case-control studies.

SETTING

California.

PATIENTS

Outbreak-associated patients and matched population controls.

MEASUREMENTS

Matched odds ratios and 95% CIs; traceback and environmental investigations of sprout and seed growers; and pulsed-field gel electrophoresis of isolates from patients, sprouts, and seeds.

RESULTS

Five sprout-associated outbreaks of salmonellosis and one outbreak of infection with nonmotile Shiga toxin-producing Escherichia coli O157 occurred. Six hundred patients had culture-confirmed disease, and two died. It is estimated that these outbreaks caused 22 800 cases of gastrointestinal illness or urinary tract infection. In the case-control studies, odds ratios for the association between illness and alfalfa sprout consumption ranged from 5.0 to infinity (all were statistically significant). Three sprout growers were implicated, and each was associated with two outbreaks. Outbreak strains of Salmonella were isolated from sprouts supplied by two sprout growers and from seeds used by the third sprout grower.

CONCLUSIONS

As currently produced, sprouts can be a hazardous food. Seeds can be contaminated before sprouting, and no method can eliminate all pathogens from seeds. Seed and sprout growers should implement measures to decrease contamination. The general public should recognize the risks of eating sprouts, and populations at high risk for complications from salmonellosis or E. coli O157 infection should avoid sprout consumption.

A multistate outbreak of Salmonella enterica serotype Baildon associated with domestic raw tomatoes

Salmonella enterica serotype Baildon, a rare serotype, was recovered from 86 persons in eight states; 87% of illnesses began during a 3-week period ending January 9, 1999. Raw restaurant-prepared tomatoes were implicated in multiple case-control studies. Contamination likely occurred on the farm or during packing; more effective disinfection and prevention strategies are needed.

Missed opportunities for preventing tuberculosis among children younger than five years of age

OBJECTIVES

Childhood tuberculosis (TB) is an important indicator of public health success in interrupting and preventing TB transmission. To determine the frequency and types of missed opportunities for preventing TB among children <5 years of age.

METHODS

We collected data from the public health records of child TB cases and their adult source cases. These children were from health jurisdictions where TB case rates in children were higher than the California average for this age group.

RESULTS

We reviewed the records for 165 children reported with TB (20% confirmed by culture). These children were evaluated for TB because of signs or symptoms of illness (32%), a contact investigation (26%), screening (22%), a source case investigation (4%), and unknown reasons (16%). Excluding 4 children infected by Mycobacterium bovis, only 59 of 161 children (37%) had a source case found. Children found in a contact investigation, born in the United States, <1 year of age, or who were black were more likely to have a source case found than children who did not have one of these characteristics. Of 43 children found in a contact investigation, improvements in contact investigations may have prevented TB in 17 of these children (40%). Among the 43 adult source cases, factors that may have facilitated transmission include delayed reporting in 23%, a delayed contact investigation in 21%, and delayed or nondocumented bacteriologic sputum conversion in 42% of culture-positive cases.

CONCLUSIONS

Important missed opportunities to prevent TB in children include the failure to find and appropriately manage adult source cases and failure to completely evaluate and properly treat children exposed to TB. Improvements in case detection, case management, and contact investigations are necessary to eliminate TB in children.

The impact of health communication and enhanced laboratory-based surveillance on detection of cyclosporiasis outbreaks in California

We investigated the timing of diagnosis, influence of media information on testing for Cyclospora, and the method used to identify cases during eight cyclosporiasis outbreaks in California in spring of 1997. We found that Internet information, media reports, and enhanced laboratory surveillance improved detection of these outbreaks.

High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts

OBJECTIVE

To determine a vehicle and point source for an outbreak of Salmonella Havana.

METHODS

The authors conducted a case-control study and traceback investigation of 14 residents of California and four from Arizona with onsets of illness from Apr 15, 1998, to June 15, 1998, and Salmonella Havana infections with identical PFGE patterns.

RESULTS

Seventeen of 18 patients were women. Seventeen were adults 20-89 years of age. Nine (50%) had diarrheal illness, 6 (33%) had urinary tract infections, 2 (11%) had sepsis, and one had an infected surgical wound after appendectomy. Four patients were hospitalized, and one died. Eating alfalfa sprouts was associated with S. Havana infection (OR = 10.0; 95% confidence interval 1.2, 83.1; P = 0.01).

CONCLUSIONS

This outbreak resulted in a high incidence of extra-intestinal infections, especially urinary tract infections, and high morbidity. Raw alfalfa sprouts, often considered a safe "heath food," can be a source of serious foodborne disease outbreaks.

An outbreak of Salmonella serogroup Saphra due to cantaloupes from Mexico

An outbreak of Salmonella serogroup Saphra (S. saphra) infections was studied by laboratory-based surveillance, case-control and trace-back studies, and a survey of cantaloupe preparation practices. Twenty-four patients with S. saphra infections had illness onsets between 23 February and 15 May 1997; 75% were </=6 years old; 23% were hospitalized. Case patients were more likely than controls to have consumed cantaloupe (88% vs. 45%; matched odds ratio [MOR], 15. 5; 95% confidence interval [CI], 1.7-139) and precut cantaloupe (59% vs. 19%; MOR, 14.5; 95% CI, 1.6-128). The trace-back study identified 1 growing region in Mexico as the source of cantaloupes for 95% of the patients who ate cantaloupes. Only 17% of case patients washed cantaloupes before cutting them. This outbreak is another example of gastrointestinal disease in the United States associated with imported contaminated produce. Consumers and retailers should wash cantaloupes before cutting them; there should be international efforts to ensure food safety.

Tuberculosis prevention in methadone maintenance clinics. Effectiveness and cost-effectiveness

To determine the effectiveness and cost-effectiveness of a program to provide screening for tuberculosis infection and directly observed preventive therapy (DOPT) in methadone maintenance clinics, we determined completion rates of screening for tuberculosis infection, medical evaluation, and preventive therapy, as well as the number of active tuberculosis cases and tuberculosis-related deaths prevented, in five clinics in San Francisco, California. Between 1990 and 1995, a total of 2,689 clients (of whom 18% were HIV-seropositive) were screened at least once. Of eligible clients, 99% received tuberculin skin tests, 96% received a medical examination, 91% began isoniazid preventive therapy, and 82% completed preventive therapy. Program effectiveness was enhanced by close collaboration between public health and methadone maintenance programs and the use of incentives and enablers. Over a 3-yr follow-up period, only one verified case of tuberculosis was reported among clients with a positive tuberculin skin test, thereby preventing as much as 95% of expected tuberculosis cases. Over 10 yr, we estimate the program would prevent 30.0 (52%) of 57.7 expected cases of tuberculosis, and 7.6 (57%) of 13.4 expected tuberculosis-related deaths. The program cost $771,569, but averted an estimated $876,229, for a net savings of $104,660 (average of $3, 724 per case prevented). Our study demonstrates that when effectively implemented, screening for tuberculosis infection and DOPT in methadone maintenance clinics is a highly cost-effective approach to prevent tuberculosis.

Two outbreaks of multidrug-resistant Salmonella serotype typhimurium DT104 infections linked to raw-milk cheese in Northern California

CONTEXT

Salmonella serotype Typhimurium definitive type 104 (DT104), with resistance to 5 drugs (ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline), has emerged as the most common multidrug-resistant Salmonella strain in the United States. However, illnesses resulting from this strain have not been associated definitively with a source in this country.

OBJECTIVE

To determine the source of 2 outbreaks of Salmonella Typhimurium DT104.

DESIGN

Matched case-control study conducted between March 24 and April 5, 1997 (outbreak 1), enhanced surveillance for new cases dating from February 1, 1997 (outbreak 2), and environmental and laboratory investigations.

SETTING AND PARTICIPANTS

The case-control study included residents of 2 adjacent counties in northern California infected with the outbreak strain of Salmonella Typhimurium var Copenhagen and age-matched controls. For enhanced surveillance, a case was defined as Salmonella Typhimurium infection in a person exposed to fresh Mexican-style cheese.

MAIN OUTCOME MEASURES

Risk factors for infection and source of implicated food.

RESULTS

Outbreak 1 peaked in February 1997; 31 patients were confirmed by culture as having Salmonella Typhimurium var Copenhagen infection, isolates of which showed indistinguishable pulsed-field gel electrophoresis (PFGE) patterns. The outbreak strain was phage type DT104 with the 5-drug resistance pattern. Sixteen cases and 25 controls were enrolled in the case-control study; 15 of 16 Salmonella Typhimurium var Copenhagen cases compared with 14 of 24 matched controls reported eating unpasteurized Mexican-style cheese, (matched odds ratio, 7.9; 95% confidence interval, 1.1-354.9). Enhanced surveillance uncovered outbreak 2, which peaked in April 1997 and was caused by a non-Copenhagen variant of Salmonella Typhimurium. During outbreak 2, Salmonella Typhimurium was isolated from 79 persons who ate fresh Mexican-style cheese from street vendors and from cheese samples and raw milk. The PFGE pattern of the milk isolate matched 1 of the 3 patterns recovered from patients; all strains were phage type DT104b with the 5-drug resistance pattern.

CONCLUSION

Raw-milk products pose a risk for multidrug-resistant Salmonella Typhimurium DT104 infections.

Preventing neonatal group B streptococcal disease: cost-effectiveness in a health maintenance organization and the impact of delayed hospital discharge for newborns who received intrapartum antibiotics

OBJECTIVES

To estimate the cost and health benefits of implementing a risk factor-based prevention strategy for early-onset neonatal group B streptococcal (GBS) disease, using baseline assumptions and costs from a health maintenance organization. With the risk factor-based strategy, intrapartum antibiotics (IPAs) would be provided to women with fever, prolonged rupture of membranes, or preterm labor. A second objective was to determine the impact of an increased length of stay for well term infants with mothers who received IPAs.

METHODS

We used decision analysis to compare the costs and benefits of the prevention strategy with usual obstetric practice for a cohort of 100 000 women and their newborn infants. We derived baseline values from a previous study based on chart review and automated cost data from a health maintenance organization in Northern California. In sensitivity analyses, we varied baseline assumptions, including additional costs for observing well term infants who received IPAs.

RESULTS

If adherence to guidelines were 100%, 17% of mothers would receive IPAs at a cost of $490,000; $1.6 million would be saved by preventing 66 GBS cases (64% reduction). The net savings would be $1.1 million and 61 life-years. The net cost is sensitive to the cost of caring for well infants who received IPAs. If each term infant of a mother who received IPAs had 1 more day of observation than other term infants, there would be a net cost of $8.1 million; the cost per GBS case prevented would be $120,000 and the cost per life-year saved would be $130,000.

CONCLUSIONS

Implementation in a health maintenance organization of a risk factor-based strategy to prevent neonatal GBS disease can prevent substantial disease and be cost saving. However, if the length of hospital stay were extended among well term infants whose mothers received IPAs, the strategy would be relatively costly compared with other medical interventions.

A study of tuberculosis among foreign-born Hispanic persons in the U.S. States bordering Mexico

In 1996, 10% of the 20,973 U.S. tuberculosis (TB) cases were among foreign-born (FB) Hispanic persons, with the four states bordering Mexico accounting for 83% of FBH cases. Limited information is available on this population's health care seeking and migration practices and on differences between FB Hispanic patients in border and nonborder areas. Therefore, we conducted interviews and record reviews for all consenting FB Hispanic TB patients from eight counties bordering Mexico (BC; n = 167) and seven urban nonborder counties (NBC; n = 158) in these States during 1995-1997. BC patients had resided in the U.S. longer than NBC patients (17.4 versus 10.8 yr; p < 0.01), had immigrated more often from Mexican border communities (62.4% versus 25.4%; p < 0.01), and had returned to Mexico more often in the past 12 mo (71.5% versus 47.3%; p < 0. 01). TB symptoms were present for >/= 6 mo in 37% of BC and 34% of NBC patients. Binational collaboration is essential for improving TB control in both countries and should extend beyond border areas of Mexico.

Viral meningitis in child care center staff and parents: an outbreak of echovirus 30 infections

OBJECTIVE

A report of five cases of viral meningitis among adults with children enrolled in a child care center prompted an investigation of risk factors for viral transmission from children to adult household members.

METHODS

To determine recent echovirus 30 (E30) infections, the authors conducted a serologic survey. To determine risk factors for infection among adult household members, they conducted a retrospective cohort study using written questionnaires.

RESULTS

Recent E30 infections were found in 84% of children tested, 57% of adult household members tested, and 47% of staff members tested. Infected adults were more likely than infected children to have clinical meningitis. Among adult household members, changing diapers was a risk factor for recent infection. Women who changed > or = 90 diapers per month had a higher infection rate than women who changed fewer diapers; in contrast, men who changed > or = 90 diapers per month had a lower infection rate than men who changed fewer diapers. Handwashing was protective: there was a negative correlation between handwashing after diaper changes and E30 infection among adults with infected children in diapers.

CONCLUSIONS

Because child care centers can be a source of enteroviral infections among adult household members, adults with viral meningitis should be questioned about their children's day care or preschool attendance. The importance of handwashing should be stressed to adults with children in day care.

Public health interventions to encourage TB class A/B1/B2 immigrants to present for TB screening

From 1985 to 1995 the proportion of all Santa Clara County, California (SCC), tuberculosis (TB) cases among recent immigrants climbed 73% (137 to 237). In SCC the efficient and cost-effective means encouraging TB Class A/B1/B2 immigrants (TBIMs) to present for TB screening and the prevalence of active TB among them were never investigated. We studied all TBIMs entering SCC from October 1, 1995 to June 30, 1996, notified to SCC by the CDC's Division of Quarantine (DQ). Encouraging TBIMs to seek TB screening, we sent letters to them promptly on the DQ notification, followed sequentially by phone calls and home visits. We determined the outcome of screening and its cost. We screened 314 of 323 (97.2%) TBIMs including 79 of 323 TBIMs who presented prior to interventions, 213 of 314 (87.3%) who responded to letters, 17 (7%) to phone calls, and 5 (2%) to home visits. Of 283 TBIMs screened 16 (5.7%) had active TB. To locate one TBIM cost $9.90 by letter, $43.25 by phone, and $129.88 by home visit. Locating one TB case cost $175.88 by letter, $696.26 by phone call. The prevalence of active TB in TBIMs is high. Our interventions resulted in low-cost TB screening and high-yield identification of active TB cases. We recommended that health departments develop a system for encouraging TBIMs to present for prompt TB screening.

Neonatal group B streptococcal infection in a managed care population. Perinatal Group B Streptococcal Infection Study Group

OBJECTIVE

In a health maintenance organization population, we determined the incidence of early-onset (at less than or equal to 7 days) neonatal group B streptococcal (GBS) disease, the sensitivity and prevalence of labor risk factors, the adherence to a protocol for intrapartum antibiotics, and the costs for care of and outcomes of affected infants.

METHODS

Mothers and infants at four health maintenance organization hospitals in northern California in 1989 to 1995 were studied retrospectively using computerized databases and chart review. In 1994, two of the four hospitals had adopted protocols similar to the ACOG recommendations for intrapartum antibiotics for women with labor risk factors (preterm, temperature 100.4F or higher, or rupture of membranes (ROM) 18 hours or more).

RESULTS

Among the 79,940 live births, the incidence of early-onset neonatal GBS infection was higher among preterm than among term infants (3.1 compared with 0.9 per 1000). Before protocol adoption, 68% of 65 infants with GBS had mothers with labor risk factors. Approximately 18% of all mothers had labor risk factors: 7.7% had preterm delivery, and 10.6% had term delivery with fever and/or ROM 18 hours or more. At the two hospitals that adopted GBS protocols, GBS incidence was reduced from 1.3 per 1000 in the preprotocol period to 0.8 per 1000 in the postprotocol period (P=.08). Six cases of neonatal GBS occurred after protocol adoption. Of these, four were not preventable under the protocol and two might have been preventable if protocol had been followed. Three of the 19 preterm infants with group B streptococcal disease died.

CONCLUSION

Risk factor-based protocols hold some promise to reduce GBS disease, but clinical strategies to promote protocol adherence are needed.

A population-based study determining the incidence of tuberculosis attributable to HIV infection

Although the tuberculosis (TB) epidemic has been attributed in part to the AIDS epidemic, few studies in the United States have measured the risk attributable to HIV infection. We linked the TB registry of Alameda County, California, 1985 to 1994, with the AIDS registry, 1982 to 1994. We defined a person with TB and HIV infection as a patient in the TB registry with the same name, race/ethnicity, gender, and date of birth as a patient in the AIDS registry. We used population and HIV seroprevalence estimates to determine the HIV-seropositive and -seronegative population at risk of TB in 1994. Of 1990 TB cases reported by Alameda County from 1985 to 1994, 116 (5.8%) had an AIDS diagnosis. Among 25- to 44-year-old TB patients, 25.2% of U.S.-born men and 8.4% of U.S.-born women had an AIDS diagnosis. In 1994, the estimated TB incidence rate in persons with HIV infection was 198.1 per 100,000 versus a rate of 13.9 of 100,000 among persons without HIV infection (rate ratio, 13.8; 95% confidence interval, 8.0, 23.8). In 1994, 93% of TB cases among HIV seropositive persons, 6.4% of all TB cases, and 16.7% of TB cases aged 25 to 44 years were attributable to HIV infection. The high attributable risk underscores the impact of HIV on the TB epidemic. All persons with HIV infection should be screened for TB, and persons with TB infection should be screened for HIV infection. TB/HIV coinfected patients should be provided with TB preventive therapy.

Bacillary angiomatosis and bacillary peliosis in patients infected with human immunodeficiency virus: clinical characteristics in a case-control study

Clinical characteristics associated with bacillary angiomatosis and bacillary peliosis (BAP) in patients with human immunodeficiency virus (HIV) infection were evaluated in a case-control study; 42 case-patients and 84 controls were matched by clinical care institution. Case-patients presented with fever (temperature, > 37.8 degrees C; 93%), a median CD4 lymphocyte count of 21/mm3, cutaneous or subcutaneous vascular lesions (55%), lymphadenopathy (21%), and/or abdominal symptoms (24%). Many case-patients experienced long delays between medical evaluation and diagnosis of BAP (median, 4 weeks; range, 1 day to 24 months). Case-patients were more likely than controls to have fever, lymphadenopathy, hepatomegaly, splenomegaly, a low CD4 lymphocyte count, anemia, or an elevated serum level of alkaline phosphatase (AP) (P < .001). In multivariate analysis, a CD4 lymphocyte count of < 200/mm3 (matched odds ratio [OR], 9.9; P < .09), anemia reflected by a hematocrit value of < 0.36 (OR, 19.7; P < .04), and an elevated AP level of > or = 2.6 mukat/L (OR, 23.9; P < .05) remained associated with disease after therapy with zidovudine was controlled for. BAP should be considered an AIDS-defining opportunistic infection and should be included in the differential diagnosis for febrile, HIV-infected patients with cutaneous or osteolytic lesions, lymphadenopathy, abdominal symptoms, anemia, or an elevated serum level of AP.

Development of a population-specific risk assessment to predict elevated blood lead levels in Santa Clara County, California

OBJECTIVES

To determine: (1) the prevalence of a blood lead level (PbB) of 10 micrograms/dL or greater and 20 micrograms/dL or greater among children aged 6 to 72 months attending the Santa Clara County (SCC), California, public clinics, (2) risk factors for elevated PbB in this population, and (3) whether an SCC public clinic population-specific risk-assessment tool and a five-question lead poisoning questionnaire developed by the Centers for Disease Control and Prevention are useful for prospectively identifying children at higher risk for elevated PbB.

METHODS

We tested for PbB 3630 children aged 6 to 72 months attending SCC public outpatient clinics between August 8, 1991, and September 1, 1992. We then conducted two matched case-control studies. Five local risk-factor questions were combined with the CDC's five-question lead poisoning questionnaire, and from May 1, 1993, to June 30, 1993, we conducted risk assessments on 247 children tested for PbB.

RESULTS

Two hundred twenty-two of 3630 children (6.1%) had a PbB of 10 micrograms/dL or greater. Thirty-nine (1.1%) had a PbB at least 20 micrograms/dL. Seventy-nine percent of the children screened and 91.0% of the children with PbB at least 10 micrograms/dL were Hispanic. Twenty percent of Mexican-born Hispanic children had a PbB of 10 micrograms/dL or greater, versus 7% of U.S.-born Hispanic children. Several factors were associated with elevated PbB among Hispanic children. For identifying children with a PbB of at least 10 micrograms/dL, the sensitivity and predictive value negative for the CDC's "high risk" definition were 30% and 93%, respectively, whereas for the SCC population-specific high-risk definition, the sensitivity was 90% and the predictive value negative was 98%.

CONCLUSIONS

Hispanic children attending SCC public clinics have risk factors for elevated PbB that were not included in the CDC's lead poisoning questionnaire. Methods for prioritizing the frequency of lead screening may be improved by combining the CDC's questions with a population-specific risk assessment.

School-based screening for tuberculous infection. A cost-benefit analysis

OBJECTIVE

To compare tuberculin screening of all kindergartners and high school entrants (screen-all strategy) vs screening limited to high-risk children (targeted screening).

DESIGN

Decision, cost-effectiveness, and cost-benefit analyses.

SETTING AND SUBJECTS

Students in a large urban and rural county.

DEFINITIONS

High risk of tuberculosis infection was defined as birth in a county with a high prevalence of tuberculosis. Low risk was defined as birth in the United States.

OUTCOME MEASURES

Tuberculosis cases prevented for 10, 000 children screened. Net costs, net cost per case prevented, benefit-cost ratio, and incremental cost-effectiveness.

RESULTS

The screen-all strategy would prevent 14.9 cases per 10,000 children screened; targeted screening would prevent 84.9 cases per 10,000 children screened. The screen-all strategy is more costly than no screening; the benefit-cost ratio is 0.58. Targeted screening would result in a net savings; the benefit-cost ratio is 1.2. Screening all children is cost saving only if the reactor rate is 20% or greater. The cost per additional case prevented for screening all children compared with targeted screening (+34 666) is more than twice as high as treatment and contact tracing for a case of tuberculosis (+16 392).

CONCLUSIONS

Targeted screening of schoolchildren is much less costly than mass screening and is more efficient in prevention of tuberculosis.

Communitywide shigellosis: control of an outbreak and risk factors in child day-care centers

OBJECTIVES

The study's objectives were to assess (1) control of a community outbreak of shigellosis through the promotion of handwashing, (2) risk factors in day-care centers, and (3) shigellosis attributable to attendance at a day-care center.

METHODS

In 1991, an outbreak of Shigella sonnei infections occurred in Lexington-Fayette County, Ky; 14 licensed child day-care centers were involved. Communitywide promotion of hand washing was instituted along with diarrhea surveillance. A case-control study compared day-care centers that had confirmed cases of shigellosis with centers that had none. A family transmission study determined those cases attributable to attendance at day-care centers.

RESULTS

The outbreak abated 3 weeks after the interventions' initiation. Day-care centers with outbreaks were more likely than those with no cases to have a food handler who changed diapers and to provide transportation for children from their homes to the center. These centers also had a higher toddler-to-toilet ratio than control centers (21 vs 12). In 58% of families with shigellosis, the first person with diarrhea during the outbreak was a child younger than 6 years; 92% of diarrheal illnesses among these children were attributable to day-care attendance.

CONCLUSIONS

Community involvement in increasing hand washing most likely resulted in control of this shigellosis outbreak. Diarrhea prevention strategies in day-care centers could prevent substantial communitywide disease.

Comparison of prevention strategies for neonatal group B streptococcal infection. A population-based economic analysis

BACKGROUND

Intrapartum antibiotics can prevent early-onset neonatal group B streptococcal (GBS) disease but have not been widely used. Obstacles include difficulty in implementing screening for GBS colonization and uncertainty about cost-effectiveness. The GBS vaccines for disease prevention are now being developed.

METHODS

We developed a decision analysis model and used standard cost-effectiveness and cost-benefit analysis methods. We compared the outcomes and costs of the recent practice of no intervention with those expected for three prevention strategies: (1) intrapartum antibiotics administered to colonized women with labor complications, (2) an alternative strategy that does not require screening but uses epidemiologic criteria and labor complications to target intrapartum antibiotics, and (3) maternal vaccination. We used data from multistate population-based surveillance to estimate the potential impact of each strategy on disease and costs in the United States.

RESULTS

Intrapartum antibiotic prophylaxis of high-risk women identified by screening could prevent approximately 3300 cases (47% of neonatal disease) annually in the United States and could save approximately $16 million in direct medical costs. Chemoprophylaxis of high-risk women identified using epidemiologic criteria could potentially be equally effective (3200 cases prevented) and would avoid the logistical difficulties of screening; the net savings would be approximately $66 million. Vaccinating 80% of pregnant women with a vaccine that prevents 80% of cases among infants born at or after 34 weeks of gestation would prevent approximately 4100 neonatal cases annually with a net savings of $131 million.

CONCLUSIONS

Universal prenatal screening for GBS and chemoprophylaxis of colonized women with labor complications is likely to be cost-beneficial in the United States. Development of alternative strategies should be further explored for populations in which GBS screening is impractical. Continued development of a GBS vaccine is an important public health priority.

Carriage of Haemophilus influenzae type b in children after widespread vaccination with conjugate Haemophilus influenzae type b vaccines

Rates of invasive Haemophilus influenzae type b (Hib) disease in children decreased very rapidly after licensure of Hib conjugate vaccines. A role for a vaccine-related reduction in nasopharyngeal carriage of Hib has been suggested. We studied oropharyngeal carriage of Hib and vaccination rates in a population of 2- to 5-year-old children in metropolitan Atlanta. Among 584 children 75% were vaccinated with an Hib conjugate vaccine, 17% had not been vaccinated and 8% had no vaccination records available. Forty-one percent of the children were colonized with H. influenzae. One child was colonized with Hib. Hib carriage (0.17%; upper 95% confidence interval boundary, 0.97%) was substantially lower than the estimates of Hib carriage from prior studies of children who had not received Hib conjugate vaccines. Our data are consistent with a decline in Hib carriage induced by widespread use of conjugate Hib vaccines, which may have contributed to the decline of Hib disease in United States children.

Body size, reproductive factors, and breast cancer survival

Mortality rates among 838 white female breast cancer patients were examined for relationships to personal characteristics assessed at time of diagnosis. These included weight and body mass index, oral contraceptive use, and prior menstrual and reproductive events. Multivariate analyses were used to determine the importance of these characteristics in predicting death rates specific for age and extent of disease at time of diagnosis. Weight was associated with poor prognosis among premenopausal patients, but not among postmenopausal patients. Premenopausal women weighing more than 140 lbs at diagnosis had death rates 1.7 times those of lighter women (P = 0.04). This effect was not explained by differences in the distribution of disease stage between the two groups. Body mass index was positively associated with mortality in both premenopausal and postmenopausal patients. In the entire group, the death rate ratio was 1.4 (P = 0.02) for obese (body mass index greater than 30.4 X 10(-3) lbs/in.2) vs lean women. Among premenopausal patients, parous women had higher mortality rates than nulliparous women (death rate ratio = 2.0, P = 0.06). Although the data were sparse, death rates were higher for women having a full-term pregnancy within 2 years of diagnosis than for premenopausal women with earlier pregnancies. Oral contraceptive use, age at menarche, age at first full term birth, and age at menopause were unrelated to mortality.