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OBJECTIVE: To determine the relation between body mass index and the development of asthma in children. DESIGN: Prospective study of 4393 asthma-free children followed for up to 14 years. SETTING: Children of participants in the National Longitudinal Survey of Youth. METHODS: Analysis was limited to children who were followed from birth and were asthma-free during the first 24 months of life. The outcome was the development of asthma during follow-up (incident asthma). Body mass index (BMI) was our main predictor of interest. Survival analyses, using time to development of asthma as the main endpoint, were stratified by sex and controlled for race/ethnicity, poverty status, and prenatal maternal smoking. RESULTS: Asthma developed in 218 (5.0 %) children during the follow-up period. The relation between BMI and incident asthma varied by sex. A BMI > or =85th percentile at age 2-3 years was a risk factor for subsequent asthma development in boys (hazard ratio (HR) 1.6 95% confidence interval (CI) 1.1, 2.4) but not girls (HR 0.8, 95% CI 0.5, 1.4). Similarly, boys with BMIs always > or =85th percentile were at increased risk for subsequent asthma development (HR 2.4, 95% CI 1.4, 4.4) but not girls (HR 1.5, 95% CI 0.7, 2.9). CONCLUSION: Boys with high body masses may be at an increased risk for developing asthma.

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The aim of this study was to examine the association between body mass index (BMI) and asthma incidence. Data from the baseline examination conducted during 1971-1975, and the first follow-up conducted during 1982-1984, of the National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study (a cohort study) was used. Asthma was self-reported or reported by proxies. BMI was calculated from measured height and weight obtained during the baseline examination. Among 9,456 participants aged 25-74 yrs who were free of asthma at baseline, 317 participants reported a diagnosis of asthma during the follow-up interview. Compared with participants with a BMI of 18.5-<25.0 kg.m(-2), the odds ratio (OR) for those with a BMI of > or =35 kg x m(-2) was 1.87 (95% confidence interval (CI) 1.12-3.13). ORs were similar for males and females. However, only 125 of the 298 participants who recalled a date of onset reported a diagnosis that occurred after their baseline examination. Among this group of participants, BMI was not significantly associated with asthma incidence (OR 1.52, 95% CI 0.62-3.77). In conclusion, although obese people reported more "incident" asthma during follow-up, it remains unclear whether this represents reactivation of previously diagnosed asthma or the onset of new cases, and whether these new cases actually represent true asthma or respiratory symptoms misdiagnosed as asthma.

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OBJECTIVE: To determine functional limitations in adults with obstructive or restrictive lung disease or respiratory symptoms. DESIGN: Cross-sectional study. SUBJECTS: Adult participants in phase 2 of the Third National Health and Nutrition Examination Survey, 1991-94. METHODS: We classified subjects using spirometric criteria into the following mutually exclusive categories using the forced expiratory volume in 1 s (FEV1), the forced vital capacity (FVC), the FEV1/FVC ratio and the presence of respiratory symptoms: severe obstruction, moderate obstruction, mild obstruction, respiratory symptoms only, restrictive lung disease and no lung disease. We developed regression models to predict functional limitations (unable to walk a quarter of a mile, unable to lift 10 pounds, needs help with daily activities) that controlled for age, race, sex, education, smoking status, body mass index and comorbid conditions. RESULTS: Severe and moderate obstruction were associated with an increased risk of being unable to walk a quarter of a mile [odds ratio (OR) 8.4, 95% confidence interval (CI) 3.6, 19.9 and OR 2.4, 95% CI 1.4, 4.0]. Restrictive lung disease and the presence of respiratory symptoms in the absence of lung function impairment were also associated with an increased risk of this outcome (OR 2.8, 95% CI 1.4, 5.6 and OR 2.8, 95% CI 2.0, 3.9). Similar results were obtained for the outcomes of being unable to lift 10 pounds or needing help with daily activities. CONCLUSIONS: The presence of obstructive or restrictive lung disease, or respiratory symptoms in the absence of lung function impairment is associated with increased functional impairment.

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BACKGROUND: A study was undertaken to define the risk of death among a national cohort of US adults both with and without lung disease. METHODS: Participants in the first National Health and Nutrition Examination Survey (NHANES I) followed for up to 22 years were studied. Subjects were classified using a modification of the Global Initiative for Chronic Obstructive Lung Disease criteria for chronic obstructive pulmonary disease (COPD) into the following mutually exclusive categories using the forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), FEV(1)/FVC ratio, and the presence of respiratory symptoms: severe COPD, moderate COPD, mild COPD, respiratory symptoms only, restrictive lung disease, and no lung disease. Proportional hazard models were developed that controlled for age, race, sex, education, smoking status, pack years of smoking, years since quitting smoking, and body mass index. RESULTS: A total of 1301 deaths occurred in the 5542 adults in the cohort. In the adjusted proportional hazards model the presence of severe or moderate COPD was associated with a higher risk of death (hazard ratios (HR) 2.7 and 1.6, 95% confidence intervals (CI) 2.1 to 3.5 and 1.4 to 2.0), as was restrictive lung disease (HR 1.7, 95% CI 1.4 to 2.0). CONCLUSIONS: The presence of both obstructive and restrictive lung disease is a significant predictor of earlier death in long term follow up.

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CONTEXT: Measles incidence in the United States is at a record low, and indigenous transmission has been interrupted in each year since 1996, suggesting that measles is no longer endemic. A national estimate of measles immunity and an understanding of predictors of measles susceptibility are essential for assuring sustained elimination of endemic disease. OBJECTIVE: To assess patterns of immunity and to determine predictors of susceptibility to measles. DESIGN/SETTING: Sera and data on participants from the third National Health and Nutrition Examination Survey (1988-1994) (NHANES III) were examined. NHANES III was a cross-sectional survey of a representative sample of the civilian, noninstitutionalized population of the United States. POPULATION: 20,100 persons 6 years of age or older were tested for measles-specific immunoglobulin G (IgG) antibody by an enzyme immunoassay. MAIN OUTCOME MEASURE: Participants with serum positive for measles antibody were considered protected or immune to measles disease. RESULTS: Prevalence of measles immunity was 93%. Nearly all persons (99%) born in the prevaccine era (before 1957) were immune. Immunity declined among persons born in the vaccine era (after 1956) to 81% among those born in 1967-1976, and increased again to 89% among those born in 1977-1988. Among persons born in the vaccine era, independent predictors of measles susceptibility varied by birth cohort and included birth in the United States, residence in a noncrowded household, residence in a nonmetropolitan area, and, among males, non-Hispanic white and Mexican American race/ethnicity. Among adults 17 years of age or older, additional predictors of susceptibility included living at or above the poverty line and not currently being married. CONCLUSIONS: Population immunity among persons 6 years of age or older is very high; however, as many as 15 million persons across the United States may lack humoral immunity. While it is unclear that the susceptible population can support continuous, indigenous transmission of measles, providers should follow current recommendations to evaluate the measles susceptibility of patients born in the vaccine era and vaccinate eligible patients.

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Asthma is a highly prevalent disease that affects the quality of life of many people in the United States. Yet there is limited descriptive epidemiological understanding of the disease, particularly at the state and local levels. Minimal surveillance of asthma is occurring across the country. Surveillance of a disease requires that public health workers have the ability to accurately identify cases, have access to needed data, and have adequate resources so that they can collect, assess, report, and use the data-all considerable challenges in the case of asthma. We consider four groups of questions that asthma surveillance should address: (1) How much asthma is there and what are the trends in asthma occurrence over time? (2) How severe is the asthma and what are the trends in asthma severity over time? (3) How well is asthma controlled and what are the trends in asthma management over time? (4) What is the cost of asthma? Because wise decision making in public health depends on the availability of appropriate data for program planning, implementation, and evaluation, we encourage increased surveillance of asthma in jurisdictions across the country.

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BACKGROUND: Women born in the United States after measles vaccine licensure in 1963 transfer less measles antibody to their infants than do older women. This may result in increased susceptibility to measles among infants. OBJECTIVE: To determine the effect of maternal year of birth on the risk for measles in infants. METHODS: We enrolled 128 unvaccinated infants

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OBJECTIVE: To report the incidence and characteristics of adult measles cases in the United States and address the adequacy of current vaccination policies to eliminate measles transmission. METHODS: Confirmed measles cases reported to the Centers for Disease Control and Prevention (CDC) from 1985 through 1995 were reviewed. Demographic data, exposure setting, and vaccination status of cases were analyzed and incidence rates calculated based on U.S. census data. MAIN OUTCOME MEASURES: Age-specific incidence rates of measles and exposure setting. RESULTS: Of the 75,204 reported measles cases of known age, 16,006 (21.3%) occurred in adults (persons > 19 years of age). The incidence in persons < 19 years of age (7.8/100,000) was 9.6 times that of all adults. Of 11,520 adult measles cases for whom vaccination status was reported, 8,055 (69.9%) indicated no prior receipt of measles vaccine. Exposure setting was unknown for the majority of adult measles cases (8,475, 52.9%); most frequently reported were college or school (2840, 17.7%), home (1443, 9.0%), or a medical setting (1286, 8.0%). International travel was associated with 289 (1.8%) adult cases. From 1993 to 1995, incidence rates in all age groups were at record low levels, with adults contributing 29.5% (467/1584) of reported cases. CONCLUSION: Although adults accounted for a steadily increasing proportion of measles cases during the study period, incidence rates in all age groups have decreased. Most adults who had measles were susceptible because of lack of vaccination rather than vaccine failure. This analysis supports current strategies to ensure the immunity of school/college-aged populations, and health care workers.

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BACKGROUND: In 1989 a second dose of measles vaccine was recommended for US children to prevent school outbreaks of measles. Coverage of school age children with a second dose remains incomplete, and data on the effectiveness of this recommendation are limited. We investigated a measles outbreak in Mesa County, CO, in December, 1994, and evaluated the efficacy of preoutbreak immunizations at an elementary school (School A) where many students had received two doses. METHODS: All reported suspected cases of measles were investigated; cases that met a clinical case definition were tested by a measles IgM antibody assay. A confirmed case required laboratory confirmation or had to meet the clinical case definition and be epidemiologically linked to a confirmed case. Vaccination records of students at School A were reviewed. The effectiveness of one and two doses of measles vaccine was estimated using logistic regression. RESULTS: Sixty-two confirmed cases were reported, including 17 at School A. At School A the attack rate in unvaccinated children (7 of 16, 44%) was higher than in those with 1 dose (10 of 320, 3%) or 2 doses (0 of 289, 0%). Estimated vaccine effectiveness was 92% for 1 dose and 100% for 2 doses. Two doses were better than one dose in decreasing the likelihood of acquiring measles (P = 0.003). CONCLUSIONS: The lower attack rate among two dose recipients provides evidence that a two dose strategy can help prevent measles in schools. Administering the second dose at elementary school entry can help prevent the persistence of susceptible cohorts of children and is likely to be important in sustaining elimination of indigenous transmission of measles in the United States.

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BACKGROUND: Despite the implementation of mass school catch-up campaigns for measles in Canada, an outbreak of measles occurred in early 1997 mostly affecting the adult population. The higher incidence in Canada in adults led us to compare immunization policies and the evolution of measles among adults in Canada and the US. METHODS: Based on information gathered from both national immunization programmes and surveillance systems. RESULTS: Although the proportion of cases occurring in adults has increased tremendously in both countries in the past decade, there was no increase in measles incidence in these populations. The most likely factors to explain the higher rate of measles occurring in adults in Canada are the younger age at administration of first dose in Canada, the delay in implementation of a second dose policy in Canada compared with the US combined with the lack of prematriculation immunization requirements in Canadian colleges and universities, and the higher rate of overseas travel to and from Canada. The situation in Canada may also have been exacerbated by incomplete efforts to control measles for many years without attempting to eliminate the disease. CONCLUSIONS: In order to prevent measles in adults, high-risk groups must be identified and catch-up for selected groups considered. Vaccination of international travellers to endemic areas should be recommended until global elimination has been achieved. Appropriate measles control strategies in younger populations seem to be effective in preventing measles in adults. The experience in Canada and the US suggests that measles transmission in adults is unlikely to be a major impediment to regional elimination or global eradication.

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OBJECTIVE: To describe the epidemiology of measles in medical settings and to evaluate the implementation and effectiveness of the 1989 Advisory Committee on Immunization Practices (ACIP) guidelines for measles immunization in healthcare workers (HCWs). DESIGN: Confirmed cases of measles reported in Clark County, Washington, from March 14 to June 2, 1996, were analyzed for characteristics of cases occurring in medical settings. A questionnaire was used to assess employee immunization (95% response rate). SETTING AND PARTICIPANTS: Reported measles cases and HCWs at community hospitals, primary-care medical facilities, a health-maintenance organization, and a multispecialty group practice. RESULTS: Of 31 cases of measles, 8 (26%) occurred in HCWs, and 5 (16%) occurred in patients or visitors to medical facilities. Cases of measles occurred in HCWs who were not required to have proof of measles immunity as defined by the 1989 ACIP guidelines. The relative risk of measles in HCWs compared to Clark County adults was 18.6 (95% confidence interval, 7.4-45.8; P<.001). A survey of medical facilities revealed that 47% had an employee measles immunization policy; only 21% met ACIP recommendations and enforced their policies. CONCLUSIONS: HCWs were at higher risk of measles than the adult population. Transmission of measles in medical settings was related to both deficiencies in, and lack of implementation of, the ACIP guidelines.

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This study investigated the frequency of mild or asymptomatic measles infections among 44 persons exposed to a student with measles during a 3-day bus trip using two buses. Questionnaires and serum samples were obtained 26-37 days after the trip. All participants had detectable measles-neutralizing antibodies, and none developed classic measles symptoms. Ten persons (23%) were IgM positive for measles, indicating recent infection. Among previously vaccinated IgM-negative persons, those who rode on bus A with the index case-patient had significantly higher microneutralization titers than those on bus B (P= .001), suggesting that some persons on bus A were infected but were IgM negative at the time of the study. Mild or asymptomatic measles infections are probably very common among measles-immune persons exposed to measles cases and may be the most common manifestation of measles during outbreaks in highly immune populations.

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To describe clinical presentation and epidemiology of US infants with congenital rubella syndrome (CRS) and to identify missed opportunities for maternal vaccination, data from CRS cases reported to the National Congenital Rubella Syndrome Registry (NCRSR) from 1985 through 1996 were analyzed. Missed opportunities for maternal vaccination were defined as missed postpartum, premarital, and occupational opportunities, that is, times when rubella vaccination is recommended but was not given. From 1985 through 1996, 122 CRS cases were reported to the NCRSR. The most frequent CRS-related defect was congenital heart disease. Of the reported infants with CRS, 44% were Hispanic. Of 121 known missed opportunities for rubella vaccination among 94 mothers of infants with indigenous CRS, 98 (81%) were missed postpartum opportunities. CRS continues to occur in the United States. Hispanic infants have an increased risk of CRS. Missed opportunities for postpartum rubella vaccination were identified for 52% of indigenous CRS cases.

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BACKGROUND: The United States has a goal to eliminate all indigenous cases of measles by the year 2000. Initial interruption of indigenous measles transmission would be expected during a period of very low measles incidence as occurred during late 1993. METHODS: Indigenous measles cases (i.e. cases acquired in the United States and not traceable to any imported case) from 1993 were investigated to determine their source of infection. The probability of sustained undetected measles transmission between isolated indigenous cases was estimated. RESULTS: Of the 312 measles cases reported for 1993, only 25 (8%) occurred after September 19. Of these only 4 cases (16%) could be classified as indigenous. The estimated probability that any of these 4 cases resulted from indigenous measles transmission in theirs or any adjoining counties was 0.05 or less. CONCLUSIONS: Interruption of indigenous measles transmission appears to have occurred for the first time throughout the United States in 1993. This event provides strong support for the current national strategy for measles elimination. However, complete elimination of indigenous measles will require maintaining high population immunity to prevent spread from imported cases and attaining global measles control to prevent the importation of measles.

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BACKGROUND: Several islands in Micronesia experienced large measles outbreaks, during 1991 through 1994. Except for Guam, none of the islands had reported measles outbreaks during the previous 20 years. METHODS: To characterize the outbreaks, measles surveillance data, hospital records and death certificates were reviewed. Preoutbreak vaccination coverage rates were assessed by reviewing public health vaccination records. Viral isolates were genetically sequenced to determine the source of transmission. Linear regression analysis was performed to assess the effectiveness of outbreak control measures. RESULTS: Between 1991 and 1994 more than 1300 measles cases and 16 measles-related deaths were reported in Micronesia. Preoutbreak vaccination coverage rates among 2-year-old children were 55 to 94%. Genetic sequencing of the viral isolates and epidemiologic investigations suggested transmission between islands and new importations from outside of Micronesia. The highest attack rates were among children ages < 5 years (20/1000) and 10 to 19 years (38/1000). Compared with attack rates among children ages < 1 and 10 to 19 years, attack rates were lower among those ages 5 to 9 years, in whom 2-dose vaccination coverage rates were highest (P < 0.001). Early and rapid implementation of mass vaccination campaigns was significantly associated with shorter duration of outbreaks (P = 0.049). CONCLUSION: The measles outbreaks in Micronesia show that island populations may be highly susceptible to measles. High two-dose vaccination coverage levels must be maintained to prevent such outbreaks. Early and rapidly implemented mass measles vaccination campaigns were effective in control of island outbreaks. Strengthening public health infrastructure and surveillance is necessary for early identification of outbreaks and rapid implementation of mass campaigns.

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Genetic analysis was conducted on 28 wild type measles viruses isolated from outbreaks or cases in the United States during 1995-1996. These viruses were members of at least 6 distinct genetic groups. However, none of these viruses was related to the group 2 viruses that were associated with the resurgence of measles in the United States between 1989 and 1992 except for a single importation from the Philippines. The sequence data support and extend previous findings showing that transmission of group 2 viruses within the United States was interrupted after 1993. The data also suggest that all measles cases that occurred in the United States in 1995-1996 were the result of importation of virus, even in instances when the source was unknown. Molecular epidemiologic studies can provide a means to measure the success of measles control programs by helping to identify the transmission pathways of the virus.

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OBJECTIVES: To describe patterns among imported measles cases to the United States. DESIGN: Descriptive analysis of national case-based surveillance data on measles cases. SETTING: United States in the period 1986 through 1994. PATIENTS: All reported confirmed cases of measles. MAIN OUTCOME MEASURES: Demographic variables, immunization history, country of exposure, and reporting state. RESULTS: The number of reported imported cases of measles to the United States has dropped from an average of 99 cases annually in 1986 through 1988 and 190 cases in 1989 through 1991 to 61 cases in 1992 through 1994. Since 1990, the number of imported cases originating in Latin America declined by 98%, despite continued increase in the number of travelers to this region; cases from other regions remained relatively constant. This decrease paralleled the rapid decrease in measles incidence in the Western Hemisphere associated with national measles elimination programs. Most imported cases occurred among children, although 22% of cases occurred among young adults. Rates of measles cases per 1 million travelers are higher among non-US citizens than among US citizens. CONCLUSIONS: The sharp decline in importations into the United States from Latin America since 1991 provides evidence of the success of measles control efforts undertaken there. The decrease in imported cases has been associated with a decline in total measles cases in the United States. Sustained elimination of measles in the United States will require improved measles control in other countries in addition to a high level of population immunity.

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Fever is a common occurrence in children who are < 5 years old and palpation of the forehead may or may not be a reliable method for determining fever in such children. In a study of 1120 Malawian children of this age attending outpatient's clinics, each child's mother and a clinical officer (CO) were asked to palpate the child's forehead and decide whether the child was febrile (felt warm or very warm) or afebrile (felt normal). The rectal temperature of each child was then taken using a thermometer and the child considered febrile if this temperature was > or = 38 degrees C. Using palpation, mothers judged 973 (86.9%) of 1120 children to be febrile and CO judged 565 (50.4%) of 1118 to be febrile, whereas thermometer readings indicated 410 (36.7%) to be truly febrile. False-positives (i.e. afebrile children judged to be febrile by palpation) accounted for 574 (59.0%) of the 973 children who were considered febrile by their mothers and 228 (40.4%) of the 565 children so considered by CO; mothers reported significantly more false-positives than CO (P < 0.05). False-negatives (i.e. febrile children judged to be afebrile by palpation) accounted for 11 (7.5%) of the 147 children who were considered afebrile by their mothers and 73 (13.2%) of the 553 children so considered by CO; CO reported significantly more false-negatives than mothers (P < 0.05). Overall, mothers were as likely as CO to misjudge a child (721/1120 v. 781/1118; P > 0.05). Although the sensitivity of mothers and CO in determining fever was similar (97.3% v. 82.2%; P > 0.05), CO gave a higher degree of specificity than the mothers (67.8% v. 19.2%; P < 0.000001). Although the present results indicate that palpation is not a reliable method of determining fever in children who are < 5 years old, caregivers should continue to use palpation as a useful first step in deciding when a child needs to be referred.

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In 1993, the World Health Organization completed the development of a draft algorithm for the integrated management of childhood illness (IMCI), which deals with acute respiratory infections, diarrhoea, malaria, measles, ear infections, malnutrition, and immunization status. The present study compares the performance of a minimally trained health worker to make a correct diagnosis using the draft IMCI algorithm with that of a fully trained paediatrician who had laboratory and radiological support. During the 14-month study period, 1795 children aged between 2 months and 5 years were enrolled from the outpatient paediatric clinic of Siaya District Hospital in western Kenya; 48% were female and the median age was 13 months. Fever, cough and diarrhoea were the most common chief complaints presented by 907 (51%), 395 (22%), and 199 (11%) of the children, respectively; 86% of the chief complaints were directly addressed by the IMCI algorithm. A total of 1210 children (67%) had Plasmodium falciparum infection and 1432 (80%) met the WHO definition for anaemia (haemoglobin < 11 g/dl). The sensitivities and specificities for classification of illness by the health worker using the IMCI algorithm compared to diagnosis by the physician were: pneumonia (97% sensitivity, 49% specificity); dehydration in children with diarrhoea (51%, 98%); malaria (100%, 0%); ear problem (98%, 2%); nutritional status (96%, 66%); and need for referral (42%, 94%). Detection of fever by laying a hand on the forehead was both sensitive and specific (91%, 77%). There was substantial clinical overlap between pneumonia and malaria (n = 895), and between malaria and malnutrition (n = 811). Based on the initial analysis of these data, some changes were made in the IMCI algorithm. This study provides important technical validation of the IMCI algorithm, but the performance of health workers should be monitored during the early part of their IMCI training.

PIP: The World Health Organization (WHO) in 1993 developed the integrated management of childhood illness (IMCI) draft algorithm which offers guidelines upon the diagnosis and treatment of acute respiratory infections, diarrhea, malaria, measles, ear infections, and malnutrition, as well as immunization status. During a 14-month study period, 1795 children aged 2 months to 5 years were enrolled in the study from the outpatient pediatric clinic of Siaya District Hospital in western Kenya, of whom 52% were male and the median age was 13 months. 51% of the children complained of having fever, 22% of having a cough, and 11% of having diarrhea. 86% of the main complaints were directly addressed by the IMCI algorithm. 1210 children had Plasmodium falciparum infection and 1432 met the WHO definition for anemia. The sensitivities and specificities for classification of illness by a minimally trained health worker using the IMCI algorithm compared to diagnosis by the physician were: pneumonia, 97% sensitivity and 49% specificity; dehydration in children with diarrhea, 51% and 98%, respectively; malaria, 100% and 0%; ear problem, 98% and 2%; nutritional status, 96% and 66%; and need for referral, 42% and 94%. Detection of fever by placing a hand upon the forehead was 91% sensitive and 77% specific. Considerable clinical overlap was observed between pneumonia and malaria, and between malaria and malnutrition. Study findings led to some changes in the IMCI algorithm.

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