COMMUNICABLE DISEASE MANUAL POLICIES / PROCEDURES
HANTAVIRUS PULMONARY
SYNDROME (HPS)
OBJECTIVE:
Control and management of Hantavirus Pulmonary Syndrome.
DESCRIPTION:
An acute zoonotic viral disease characterized by fever, myalgias and GI
complaints followed by the abrupt onset of respiratory distress and
hypotension. The illness progresses rapidly to severe respiratory failure and
shock. An elevated hematocrit, hypoalbuminemia and thrombocytopenia are
found in most cases. The crude mortality rate is approximately 40%-50%; it
was 43% of the first 217 cases identified. In survivors, the recovery from acute
illness is rapid, but full convalescence may require weeks to months.
Restoration of normal lung function generally occurs, but pulmonary function
abnormalities may persist in some individuals. Renal and hemorrhagic
manifestations are usually absent except in some severe cases.
Multiple hantaviruses have been identified in the Americas: Sin Nombre virus
is the agent responsible for the 1993 epidemic in southwest USA and most of
the other cases identified in North America. Other strains associated with
human disease include Black Creek Canal and Bayou viruses (southeastern
USA), New York-1 and Monongahela viruses (eastern USA), Andes virus
(Argentina, Chile), Laguna Negra virus (Paraguay, Bolivia) and Juquitiba virus
(Brazil).
Rodents, the natural hosts for the hantaviruses, acquire a lifelong,
asymptomatic, chronic infection with prolonged viruria and virus in saliva.
Humans acquire infection through direct contact with infected rodents, rodent
droppings, nests, inhalation of aerosolized virus particles from rodent urine,
droppings, or saliva. Rarely, infection may be acquired from rodent bites or
contamination of broken skin with excreta. Person-to-person transmission of
the viruses in the United States has not been demonstrated, but a few cases of
person-to-person spread of Andes virus have been reported from Patagonia,
South America. At-risk activities include handling or trapping rodents, cleaning
or entering closed, rarely used rodent-infested structures, cleaning feed
storage or animal shelter areas, hand plowing, and living in a home with an
increased density of mice in or around the home. For backpackers or campers,
sleeping in a structure also inhabited by rodents has been associated with
HPS. Weather conditions resulting in exceptionally heavy rainfall and improved
rodent food supplies can result in a large increase in the rodent population.
The increased rodent population results in more frequent contact between
humans and infected mice and may account for recently recognized outbreaks.
Most cases occur during spring and summer, and the geographic location is
determined by the habitat of the rodent carrier. Protection and immunity
conferred by previous infection in unknown. Sin Nombre virus is transmitted by
the deer mouse, Peromyscus maniculatus; Black Creek Canal virus is
transmitted by the cotton rat, Sigmodon hispidus; Bayou virus is transmitted by
the rice rat, Oryzomys palustris; and New York virus is transmitted by the whitefooted mouse, Peromyscus leucopus.
The incubation period may be 1 to 6 weeks after exposure to infected rodents,
their saliva, or excreta but has not been established definitely.
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EQUIPMENT:
MDSS User Manual and the MDSS Communicable Disease Case Form.
MDCH website at www.michigan.gov/cdinfo and CDC website 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 24 hours post referral AND ENTER
INTO MDSS WITHIN 24 HOURS OF RECEIPT OF REFERRAL.
PROCEDURE:
A.
B.
Case Investigation
1.
Referral received per phone call, laboratory results, or
automatically through MDSS.
2.
Document all case investigation proceedings.
3.
Contact MD and/or client to start process of completing disease
specific form in MDSS.
Case Definition
1.
Clinical Case Definition:
An illness characterized by one or more of the following clinical
features:
 A febrile illness (i.e., temperature > 101.0º F [>38.3º C])
characterized by bilateral diffuse interstitial edema that may
radiographically
resemble
ARDS,
with
respiratory
compromise requiring supplemental oxygen, developing
within 72 hours of hospitalization, and occurring in a
previously healthy person.

2.
Case Classification:

C.
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An unexplained respiratory illness resulting in death, with an
autopsy
examination
demonstrating
noncardiogenic
pulmonary edema without an identifiable cause.
Confirmed:
confirmed.
A clinically compatible case that is laboratory
Lab Criteria for Diagnosis
1.
Detection of hantavirus-specific IgM antibodies by using Elisa,
Western blot or strip immunoblot techniques or rising titers of
hantavirus-specific IgG antibodies, or
2.
Detection of hantavirus-specific ribonucleic acid sequence by
polymerase chain reaction in clinical specimens, or
3.
Detection of hantavirus antigen by immunohistochemistry.
4.
Laboratory testing should be performed or confirmed at a
reference laboratory. Because the clinical illness is nonspecific
and Acute Respiratory Distress Syndrome (ARDS) is common, a
screening case definition can be used to determine which
patients to test. In general, a predisposing medical condition
(e.g., chronic pulmonary disease, malignancy, trauma, burn, and
surgery) is a more like cause of ARDS than HPS, and patients
who have these underlying conditions and ARDS need not be
tested for hantavirus.
D.
E.
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Control Measures
1.
Hantavirus infections of humans occur primarily in adults and are
associated with domestic, occupational, or leisure activities
bringing humans into contact with infected rodents, usually in a
rural setting. Eradicating the host reservoir is not feasible. The
best currently available approach for disease control and
prevention is risk reduction through environmental hygiene
practices that discourage rodents from colonizing the home and
work environment and that minimize aerosolization and contact
with virus in saliva and excreta. Hantaviruses, because of their
lipid envelope, are susceptible to most disinfectants, including
diluted bleach solutions, detergents, and most general
household disinfectants.
2.
Measures to decrease exposure in the home and workplace
include eliminating food sources available to rodents in
structures used by humans, limiting possible nesting sites,
sealing holes and other possible entrances for rodents, and
using "snap traps" and rodenticides. Other methods include
using a 10% bleach solution to disinfect dead rodents and
wearing rubber gloves before handling trapped or dead rodents.
Gloves and traps should be disinfected after use. Before
entering areas with potential rodent infestations, doors and
windows should be opened to ventilate the enclosure. People
entering these areas should avoid stirring up or breathing
potentially contaminated dust. Dusty or dirty areas or articles
should be moistened with a 10% bleach or other disinfectant
solution before being cleaned. Brooms and vacuum cleaners
should not be used to clean rodent-infested areas.
3.
Efficacious chemoprophylaxis measures or vaccines are not
available. HPS has not been associated with nosocomial or
person-to-person transmission in the USA and does not need
isolation or quarantine measures for patient or contacts.
MDSS Case Report
1.
Complete case investigation using disease specific form in
MDSS.
2.
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:
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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
MMWR, Volume 46, 1997