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Surveillance Dona Schneider, PhD, MPH
Surveillance is the ongoing, systematiccollection, analysis, and interpretation of health data essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely feedback of these data to those who need to know. Centers for Disease Control
Surveillance can… • Estimate the magnitude of a problem • Determine geographic distribution of illness • Detect epidemics/outbreaks • Generate hypotheses, stimulate research • Evaluate whether control measures work • Monitor changes in infectious agents • Detect changes in health practices
Examples: • Morbidity and Mortality Weekly Report • http://www.cdc.gov/mmwr/ • SEER Cancer Registry • http://seer.cancer.gov/ • US Vital Statistics • http://wonder.cdc.gov/welcome.html
National Notifiable Diseases Surveillance System (NNDSS) – produces the data in the MMWR • The reportable diseases list is revised periodically by the Council of State and Territorial Epidemiologists (CSTE) and the Centers for Disease control (CDC) • States report their cases to the CDC • Internationally quarantinable diseases (i.e., cholera, plague and yellow fever) must be reported to the World Health Organization (WHO)
Anthrax Avian influenza Crimean-Congo haemorrhagic fever (CCHF) Dengue/dengue haemorrhagic fever Ebola haemorrhagic fever Hepatitis Influenza Lassa fever Marburg haemorrhagic fever Meningococcal disease Plague Rift Valley fever Severe Acute Respiratory Syndrome (SARS) Smallpox Tularaemia Yellow fever The Epidemic and Pandemic Alert and Response (EPR) Program at the WHO Monitors…
Surveillance for communicable diseases is important… • The world population is highly mobile • International travel and troop movements increase the risk of communicable disease transmission • Forced migration for war and famine, and voluntary immigration increase communicable disease risk
Types of Surveillance • Passive • Inexpensive, provider-initiated • Good for monitoring large numbers of typical health events • Under-reporting is a problem • Active • More expensive, Health Department-initiated • Good for detecting small numbers of unusual health events • Enhanced • Rapid reporting and communication between surveillance agencies and stakeholders • Best for detecting outbreaks and potentially severe public health problems
Syndromic surveillance • Allows us to identify groups of signs and symptoms that precede diagnosis and signal a sufficient probability of a case or an outbreak that warrants a further public health response • Example: EBOLA VIRUS
Sentinel Surveillance • Monitors • Sites – volcanos • Events – 9/11 • Providers – ERs • Vectors/animals • Rabies • West Nile
SENTINEL EVENT Nov 12, 2001 - 9:17 am Flight AA 587 Crashes in Rockaways 7-Zip Surveillance showed: 27 Obs / 10 Exp Resp Emergencies p<0.001 31 Obs / 16 Exp Hospital Events p<0.05
Investigation • Chart review in one hospital (9 cases) • Smoke Inhalation (1 case) • Atypical Chest Pain / Anxious (2 cases) • Shortness of Breath - Psychiatric (1 case) • Asthma Exacerbation (3 cases) • URI/LRI (2 cases) • Checked same-day logs at 2 hospitals Increase not sustained
Blood Lead Measurements 1975-1981 110 18 Predicted blood lead 100 Lead used in gasoline (thousands of tons) 16 90 Mean blood lead levels g/dl 80 Gasoline lead 14 70 Observed blood lead 12 60 50 10 40 30 8 1975 1976 1977 1978 1979 1980 1981 Year Source: Pirkle et al JAMA 272:284-91, 1994
Reported Salmonella Isolates,* United States, 1976-2001 *Data from Public Health Laboratory Information System (PHLIS). Source: CDC. Summary of notifiable diseases. 2001.
Recent Occupational Monitoring Efforts for Sentinel Events Include… • Biodetection Systems (BDS) in NJ post offices to detect anthrax and soon, ricin • Biowatch, an air monitoring system in New York City and 30 other cities
Free Resources World Health Organization DISMOD Software http://www.who.int/healthinfo/boddismod/en/ Centers for Disease Control Epi Info and Epi Map http://www.cdc.gov/epiinfo/
Good surveillance does not necessarily ensure the making of right decisions, but it reduces the chances of wrong ones. Alexander D. Langmuir NEJM 1963;268:182-191