CHS Web Tool
Kit for Investigating a Respiratory Disease Outbreak
An outbreak is defined as illness
levels above what is normally expected; in certain
situations, even one case of a disease may be considered
an outbreak.
As a rule of thumb, in a school or community setting,
respiratory outbreaks may be defined as 5 or more new
cases of influenza-like activity (ILI) (fever plus sore
throat or cough) in a one week period. For skilled
nursing facilities, respiratory outbreaks may be defined
as either 3 or more ILI cases in a one week period or
1 lab confirmed influenza case.
However there may be exceptions to these
definitions depending on severity of disease or size of
facility/affected population. CHS personnel need to use
their best judgment to determine if the level of
respiratory illness is above baseline and thus should be
considered an “outbreak” regardless of the actual number
of illnesses.
An outbreak is over when the level of illness is
back to “normal” or when there are no new cases of
illness for >2 incubation periods of the pathogen
involved.
Decision Tree
tool for information on when to investigate outbreaks
and what forms to use
For decision tree tool
click here
Report forms
Go to
ACDC epidemiology forms web page
B-73 Manual of
Departmental Rules, Regulations and Control Procedures
The acute communicable disease
control procedures for the County of Los Angeles, based
on the Health and Safety Code, the California Code of
Regulations, and rules of the California Department of
Public Health. This manual is the official Department
interpretation of those laws, regulations and rules.
Go to
B73 web page and use the following chapters:
Nasopharyngeal Specimen Collection Information
Laboratory Tests
Health Education
Materials
School Outbreak
Materials
Click here for:
CDC Guidelines on Investigating Respiratory Outbreaks
