COMMUNICABLE DISEASE MANUAL POLICIES/PROCEDURES
LEGIONELLOSIS
OBJECTIVE:
The control and management of Legionellosis.
DESCRIPTION:
An acute bacterial disease with two distinct manifestations: “Legionnaires’
Disease” and “Pontiac Fever”. Both are characterized initially by anorexia,
malaise, myalgia and headache. Within a day, there is usually a rapidly rising
fever associated with chills. A non-productive cough is common; abdominal pain
and diarrhea occur in many patients. In Legionnaires disease, radiograph may
show patchy areas of consolidation, which may progress to bilateral involvement
and ultimately, to respiratory failure. Pontiac Fever is not associated with
pneumonia or death; patients recover spontaneously in 2-5 days without
treatment. Incubation period for Legionnaires’ disease is 2-10 days; for Pontiac
Fever it is 1-2 days. Legionella species are aerobic bacilli that stain gramnegative. At least 18 different species have been implicated in human disease,
but most documented Legionella infections in the United States are caused by
the Legionella pneumophila serogroup 1. Legionnaire’s disease is acquired
through inhalation of aerosolized water contaminated with L pneumophila.
Person-to-person transmission has not been demonstrated. More than 80% of
cases are sporadic; the sources of infection may be related to exposure to L
pneumophila-contaminated water in the patient's home, workplace, or location of
medical therapy or to aerosol-producing devices in public places. Outbreaks
have been ascribed to common-source exposure to contaminated cooling
towers, evaporative condensers, potable water systems, whirlpool spas,
humidifiers, and respiratory therapy equipment. Nosocomial infections occur and
often have been traced to a hot water supply. The disease occurs most
commonly in elderly and immunocompromised people.
EQUIPMENT:
MDSS User Manual (disease specific form will be found in MDSS). Also MDCH
Web site at www.michigan.gov/cdinfo and CDC Web site at
www.cdc.gov/diseasesconditions/az/a.html.
POLICY:
Legal Responsibility: Michigan's communicable disease rules of Act No. 368 of the
Public Acts of 1978, as amended, being 333.5111 of the Michigan Compiled Laws.
Follow-up time within 72 hours of receiving referral AND ENTER INTO
MDSS WITHIN 24 HOURS OF RECEIPT OF REFERRAL.
PROCEDURE:
A.
B.
Case Investigation
1.
Referral received per phone
automatically through MDSS.
2.
Document all case investigation proceedings.
3.
Contact MD and/or client to start process for completing disease
specific form in MDSS.
laboratory
results,
or
Case Definition
1.
D:\106747211.docPage 1 of 4
call,
Legionellosis is associated with
epidemiologically distinct illnesses:
two (2) clinically and
Legionnaires’ disease,
which is characterized by fever, myalgia, cough, and clinical or
radiographic pneumonia; and Pontiac fever, a milder illness
without pneumonia. Both lab confirmation AND the diagnosis of
pneumonia (clinically or via x-ray) is needed. A positive lab
without pneumonia is Pontiac Fever.
C.
Lab Criteria for Diagnosis
1.
Laboratory Case Confirmation:

2.
One of the following lab requirements must be met:

Culture: Isolation of any Legionella organism from
respiratory secretions, lung tissue, pleural fluid or
other normally sterile fluid. The isolation of any
serogroup of Legionella is a confirmed case. OR

Urine antigen:
Detection of Legionella
pneumophilia serogroup 1 antigen in urine using
validated reagents. Urine antigen is NOT the
same thing as a culture. OR

Seroconversion:
Fourfold or greater rise in
specific serum antibody titer to Legionella
pneumophilia serogroup 1 using validated
reagents. A fourfold rise in serum antibody to
any
serogroup
besides
pneumophilia
serogroup 1 is a SUSPECT case.
Suspect: Laboratory Criteria:

One of the following lab requirements must be met:


D:\106747211.docPage 2 of 4
By seroconversion: Fourfold or greater rise in
antibody titer to specific species or serogroups of
Legionella other than L. pneumophilia serogroup 1
(e.g., L. micdadei, L. pneumophilia serogroup 6).
By seroconversion: Fourfold or greater rise in
antibody titer to multiple species of Legionella
using pooled antigen and validated reagents.

By the detection of specific Legionella antigen or
staining of the organism in respiratory secretions,
lung tissue, or pleural fluid by direct fluorescent
antibody (DFA) staining, immunohistochemistry
(IHC), or other similar method, using validated
reagents.

By detection of Legionella species by a validated
nucleic acid assay.
D.
E.
E.
D:\106747211.docPage 3 of 4
Case Classification
1.
Suspect: A clinically compatible case that meets at least one of
the suspect laboratory criteria.
2.
Confirmed: A clinically compatible case that meets at least one
of the confirmatory laboratory criteria
3.
MDSS Case Investigation Form: The diagnosis must be
marked in MDSS under the clinical information section. This
is often left unmarked.
4.
Travel-associated: a Case that has a history of spending at least
one night away from home, either in the same country of
residence or abroad, in the 10-14 days before onset of illness.
Please give dates, if available.
5.
Travel, dental work, hospital exposure should only be noted for
the two (2) weeks prior to onset. Please give dates, if available.
6.
Please collect information about worksites and/or school. This
can be very important in outbreak situations.
Control Measures
1.
Search for additional cases (household, business, etc.) due to
infection from a common environmental source. (NOTE: Personto-person transmission has not been documented.)
2.
Educate regarding decontamination of implicated sources and
preventive measures (i.e., air conditioning systems, humidifiers,
etc.)
3.
Refer to Environmental Health for follow-up.
MDSS Case Report
1.
2.
Complete case investigation using disease specific form in MDSS
Notify CD Supervisor that the case report is ready for review.
PHN will be notified if corrections are needed prior to closing case
in MDSS.
3.
CD Supervisor reviews case for completeness and closes MDSS
case report.
RESOURCES:
D:\106747211.docPage 4 of 4
Current Red Book
Current Control of Communicable Diseases Manual
Current disease specific “Fact Sheet”
Websites: www.cdc.gov/diseasesconditions/az/a.html
www.michigan.gov/cdinfo