ABSTRACT. Objectives. To estimate the proportion of children 1 to 5 years of age who received blood lead testing during 1988 -1994 and to assess whether predictors of testing coincided with predictors of elevated blood lead levels.Design. Cross-sectional analysis of data from the Third National Health and Nutrition Examination Survey.Participants. US children 1 to 5 years of age. Outcome Measures. Prevalence of blood lead testing and elevated blood lead levels among children 1 to 5 years of age and odds ratios for factors predicting blood lead testing and elevated blood lead levels.Results. Overall, 6.3% had elevated blood lead levels and 10.2% had undergone previous blood lead tests. Being of minority race/ethnicity, living in an older home, residing in the Northeast or Midwest regions of the United States, being on Medicaid, having a head of household with <12 years of education, and having a history of anemia were significant factors in both models. Additional independent risk factors for an elevated blood lead level included being sampled in phase 1 of the survey, being 1 to 2 years of age, not having a regular doctor, and being sampled during the summer months. Additional independent correlates of a previous blood lead test included having moved less than twice in one's lifetime, having a female head of household, and having parents whose home language was English. Of an estimated 564 000 children 1 to 5 years of age who had elevated blood lead levels and no previous screening test in 1993, 62% were receiving Medicaid, 40% lived in homes built before 1946, and 34% were black, non-Hispanic.Conclusions. Lead screening was more frequent among children with risk factors for lead exposure. However, among children with elevated blood lead levels, only one third had been tested previously. In 1993 an estimated 564 000 children 1 to 5 years of age had elevated blood lead levels but were never screened. Physicians should screen Medicaid-eligible children and should follow state or local health department recommendations about identifying and screening other at-risk children. In areas where no health department guidelines exist, physicians should screen all children or screen based on known risk factors. Pediatrics 2000;106(6). URL: http://www.pediatrics.org/cgi/content/full/106/6/e79; lead poisoning, blood lead, children, screening, epidemiology, risk factors.

Rapidly increasing and unexplained mortality in commercial poultry flocks may signal the presence of a highly transmissible and reportable disease. Activation of an infectious-disease surveillance system occurs when a key production parameter, i.e., mortality, changes. Various triggers have been proposed to alert producers when mortality exceeds normal limits for a given production system to enable early detection of such diseases. In this article we demonstrate that a simple moving-average trigger is useful for detecting any disease syndrome in caged table-egg layer flocks that manifests itself as sudden, rapidly increasing mortality. We superimposed HPAI disease mortality output data derived from a disease transmission model and from a naturally occurring HPAI outbreak onto normal mortality data from 12 healthy commercial egg-layer flocks, and compared the performance of 7-day moving-average triggers to previously proposed triggers. The moving-average trigger is more efficient, resulting in fewer false-positive alerts and an earlier time to disease detection. It can be easily calculated by using a computer spreadsheet providing only 7 days of mortality data and can be practically and inexpensively implemented by large commercial poultry integrators. A moving-average trigger can be an active component of a production-based surveillance system.

Early detection of highly pathogenic avian influenza (HPAI) infection in commercial poultry flocks is a critical component of outbreak control. Reducing the time to detect HPAI infection can reduce the risk of disease transmission to other flocks. The timeliness of different types of detection triggers could be dependent on clinical signs that are first observed in a flock, signs that might vary due to HPAI virus strain characteristics. We developed a stochastic disease transmission model to evaluate how transmission characteristics of various HPAI strains might effect the relative importance of increased mortality, drop in egg production, or daily real-time reverse transcriptase (RRT)-PCR testing, toward detecting HPAI infection in a commercial table-egg layer flock. On average, daily RRT-PCR testing resulted in the shortest time to detection (from 3.5 to 6.1 days) depending on the HPAI virus strain and was less variable over a range of transmission parameters compared with other triggers evaluated. Our results indicate that a trigger to detect a drop in egg production would be useful for HPAI virus strains with long infectious periods (6-8 days) and including an egg-drop detection trigger in emergency response plans would lead to earlier and consistent reporting in some cases. We discuss implications for outbreak control and risk of HPAI spread attributed to different HPAI strain characteristics where an increase in mortality or a drop in egg production or both would be among the first clinical signs observed in an infected flock.

Emergency response during a highly pathogenic avian influenza (HPAI) outbreak may involve quarantine and movement controls for poultry products such as eggs. However, such disease control measures may disrupt business continuity and impact food security, since egg production facilities often do not have sufficient capacity to store eggs for prolonged periods. We propose the incorporation of a holding time before egg movement in conjunction with targeted active surveillance as a novel approach to move eggs from flocks within a control area with a low likelihood of them being contaminated with HPAI virus. Holding time reduces the likelihood of HPAI-contaminated eggs being moved from a farm before HPAI infection is detected in the flock. We used a stochastic disease transmission model to estimate the HPAI disease prevalence, disease mortality, and fraction of internally contaminated eggs at various time points postinfection of a commercial table-egg layer flock. The transmission model results were then used in a simulation model of a targeted matrix gene real-time reverse transcriptase (RRT)-PCR testing based surveillance protocol to estimate the time to detection and the number of contaminated eggs moved under different holding times. Our simulation results indicate a significant reduction in the number of internally contaminated eggs moved from an HPAI-infected undetected flock with each additional day of holding time. Incorporation of a holding time and the use of targeted surveillance have been adopted by the U.S. Department of Agriculture in their Draft Secure Egg Supply Plan for movement of egg industry products during an HPAI outbreak.