Epidemiologic Surveillance & Epidemic Outbreak Invsetigation Flashcards
• Aka disease outbreaks
EPIDEMICS
Occurrence of disease at an unusual or unexpected, elevated frequency
EPIDEMICS
We cannot really determine if a disease occurrence is unusual or unexpected unless you do a
disease surveillance
A reliable ___________ is a helpful tool for us to define the usual rates of disease in an area
surveillance system
• process of collecting, analyzing, interpreting, and reporting data on the incidence of death, diseases, and injuries and the prevalence of certain conditions
SURVEILLANCE
__________ in the context of health, involves any health states/status including normal or abnormal conditions, not just a disease (i.e., pregnancy; surveillance for the no. of pregnant women, increase in the no. of teenage pregnancy; injuries: vehicular accidents, work-related accidents; death: mortality rate, death rate due to a particular disease, etc.)
Surveillance
To monitor the health status of the population
Surveillance
– health of the population as a whole
Public health
is considered as the foundation of disease control efforts
Surveillance
INTENSITY OF SURVEILLANCE
ACTIVE VS. PASSIVE
• healthcare practitioners are required to report disease using appropriate forms and instructions
• all are expected to record all cases of reportable diseases
• Simply put, the healthcare workers will report to the agency responsible for a surveillance
PASSIVE SURVEILLANCE
Most widely used surveillance system because it requires less budget
PASSIVE SURVEILLANCE
• requires periodic telephone calls, electronic contact, or personal visits to the reporting individuals and institutions to obtain required data
• opposite of passive surveillance
• In this system, the agency that enacts the surveillance system is the one that actively seeks out cases from healthcare workers
ACTIVE SURVEILLANCE
More labor intensive and costly compared to passive surveillance
ACTIVE SURVEILLANCE
– agencies actively seek out the persons who made contact with a patient who is COVID positive
Contact tracing
FUNCTIONS OF DISEASE SURVEILLANCE
• Establishment of Baseline Data
• Evaluation of Time Trends
• Identification and Documentation of Outbreaks
• Evaluation of Public Health and Disease Interventions
• Setting of Disease Control Priorities
• Study of Changing Patterns of Disease
_______rates and patterns of diseases can be known only if there is a regular reporting and surveillance system
baseline (or usual)
evaluation of disease patterns over longer periods of time (i.e., several years of decades of data)
Secular (Long-Term) Trends
– criteria that a physician or an epidemiologist must consider for us to include a certain individual in the cases
Case definition
– individual that suffer from a particular disease
Cases
Analyze if the ______ is caused by an increase in the number of cases or an artifact of a change in the manner of reporting or change in the detection of the disease.
secular trend
the x-axis is an arithmetic scale (addition), the y-axis is a logarithmic scale (multiplication)
Semilogarithmic graph
– tells you how many of the cases have died from that particular disease ( death/ cases) ; tells you how deadly the disease is
CFR (case fatality ratio)
both x and y axis are in an arithmetic scale
arithmetic graph
Has equal gaps which means it has equal numbers of dates in between (addition of how many days)
Arithmetic graph
are not used in epidemiological studies
exponential graphs
- Graph used in epidemiological studies and is truly reflective of what is happening in the real world
logistic curve or sigmoid graph
limited to a certain maximum of death. As the graph goes up, as more people get infected, less people are becoming susceptible. In this case, the virus has nowhere to go, so the virus then slows down.
logistic curve or sigmoid graph
– many infectious diseases (depending on the route of spread show this type of pattern. The upward and downward trend and the pattern of the disease is based on the seasonal changes
Seasonal Variation
Seasonal Variation (RAF)
Respiratory
Arthropod
Fecal-Oral
: usually have a much higher incidence in the winter and early spring in the Northern Hemisphere. (In the Philippines, occurs mostly during rainy season).
Respiratory Route
: summer or early autumn. (PHL; mosquito = dengue)
Arthropod vectors
: most common in summer. Partly, because of the warm weather that facilitates the growth of bacteria
Fecal-oral route
• January 1 to December 31 of the same year
CALENDAR YEAR
CALENDAR YEAR
January 1 to December 31 of the same year
• Month of the lowest incidence in one year to the same month in the next year.
EPIDEMIOLOGIC YEAR
EPIDEMIOLOGIC YEAR
Month of the lowest incidence in one year to the same month in the next year.
– occurrence of disease at an unusual (or unexpected) frequency
Epidemic or Disease Outbreak
– the critical number of cases or density of susceptible hosts that have the disease required for an epidemic to occur. It is used to confirm the emergence of an epidemic so as to stepup appropriate control measures.
Epidemic Threshold
, is the occurrence of disease at an unusual (or unexpected) frequency.
epidemic, or disease outbreak
: broken blue lines, should be crossed before declaring an outbreak, derived from the seasonal baseline data
Epidemic threshold
: solid blue line, data gathered from continued surveillance
Seasonal baseline data
: black line, goes way beyond the threshold then that is considered as an outbreak or epidemic.
Actual proportion of deaths
• Rapid detection of major increases in the most likely biological agents
SURVEILLANCE FOR BIOTERRORISM
• Characterize syndromes that would be consistent with agents of particular concern
SYNDROMIC SURVEILLANCE
The failure of a vaccine to produce satisfactory immunity or the failure of people to use the vaccine can be detected by one of the following:
• A lack of change in disease rates
• An increase in disease rates after an initial decrease, as in the previous example of the polio vaccine
• An increase in disease rates in a recently vaccinated group, as occurred after the use of defective lots of inactivated polio vaccine in the 1950s.
• Refers to the process of monitoring the safety of drugs or vaccines once they reach the market, after the successful completion of clinical trials
POST-MARKETING SURVEILLANCE
Primary purpose: to identify previously unrecognized adverse effects as well as positive effects
POST-MARKETING SURVEILLANCE
Data on the patterns of diseases for the current time and recent past can help governmental and voluntary agencies establish priorities for disease control efforts. This is not a simple counting procedure.
Setting of Disease Control Priorities
Study of Changing Patterns of Disease
By____________________________ over time in populations and subpopulations, epidemiologists can better understand the changing patterns of the disease.
studying the patterns of occurrence of a particular disease
is the foundation of public health control of disease.
It may be active or passive.
Its functions include determining the baseline rates of disease, detecting outbreaks, and evaluating control measures.
Surveillance of disease activity
are used for setting disease control policy. The investigation of disease outbreaks is a primary function of public health agencies, but the practicing physician makes important contributions in detecting and reporting acute outbreaks.
Surveillance data
