Hantavirus Pulmonary Syndrome (HPS) : Part 8

by CDC

(Page 8 of 17)

What Is the Treatment for HPS?

At the present time, there is no specific treatment or "cure" for hantavirus infection. However, we do know that if the infected individuals are recognized early and are taken to an intensive care unit, some patients may do better. In intensive care, patients are intubated and given oxygen therapy to help them through the period of severe respiratory distress.

The earlier the patient is brought in to intensive care, the better. If a patient is experiencing full distress, it is less likely the treatment will be effective.

Therefore, if you have been around rodents and have symptoms of fever, deep muscle aches and severe shortness of breath, see your doctor immediately. Be sure to tell your doctor that you have been around rodents - this will alert your physician to look closely for any rodent-carried disease such as HPS.

Hantaviruses Technical Information

HPS Case Definition

Hantavirus Pulmonary Syndrome Clinical description

Hantavirus pulmonary syndrome (HPS), commonly referred to as hantavirus disease, is a febrile illness characterized by bilateral interstitial pulmonary infiltrates and respiratory compromise usually requiring supplemental oxygen and clinically resembling acute respiratory disease syndrome (ARDS). The typical prodrome consists of fever, chills, myalgia, headache, and gastrointestinal symptoms. Typical clinical laboratory findings include hemoconcentration, left shift in the white blood cell count, neutrophilic leukocytosis, thrombocytopenia, and circulating immunoblasts.

Clinical case definition

An illness characterized by one or more of the following clinical features:

A febrile illness (i.e., temperature greater than 101.0 F {greater than 38.3 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.

An unexplained respiratory illness resulting in death, with an autopsy examination demonstrating noncardiogenic pulmonary edema without an identifiable cause

Laboratory criteria for diagnosis

Detection of hantavirus-specific immunoglobulin M or rising titers of hantavirus-specific immunoglobulin G, or Detection of hantavirus-specific ribonucleic acid sequence by polymerase chain reaction in clinical specimens, or Detection of hantavirus antigen by immunohistochemistry.

Case classification Confirmed: a clinically compatible case that is laboratory confirmed

Comment

Laboratory testing should be performed or confirmed at a reference laboratory. Because the clinical illness is nonspecific and 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 likely cause of ARDS than HPS, and patients who have these underlying conditions and ARDS need not be tested for hantavirus.

Clinical Disease Manifestations

Presentation and First Evaluation

Patients with HPS typically present in a very nonspecific way with a relatively short febrile prodrome lasting 3-5 days. In addition to fever and myalgias, early symptoms include headache, chills, dizziness, non-productive cough, nausea, vomiting, and other gastrointestinal symptoms. Malaise, diarrhea, and lightheadedness are reported by approximately half of all patients, with less frequent reports of arthralgias, back pain, and abdominal pain. Patients may report shortness of breath, (respiratory rate usually 26 - 30 times per minute). Typical findings on initial presentation include fever, tachypnea and tachycardia. The physical examination is usually otherwise normal.

The diagnosis is seldom made at this stage, as cough and tachypnea generally do not develop until approximately day seven. Once the cardiopulmonary phase begins, however, the disease progresses rapidly, necessitating hospitalization and often ventilation within 24 hours.

Signs that make a diagnosis of HPS unlikely include rashes, conjunctival or other hemorrhages, throat or conjunctival erythema, petechiae, and peripheral or periorbital edema.

Clinical Assessment

If a hantavirus infection is suspected, a CBC and blood chemistry should be repeated every 8 to 12 hours.

A fall in the serum albumin and a rise in the hematocrit may indicate a fluid shift from the patient's circulation into the lungs. The white blood cell count tends to be raised with a marked left shift. The percentage of white blood cells precursors may be as high as 50% and atypical lymphocytes are frequently present, usually at the time of onset of pulmonary edema.

In about 80% of individuals with HPS, the platelet count is below 150,000 units. A dramatic fall in the platelet count may herald a transition from the prodrome to the pulmonary edema phase of the illness.

The most severe cases of HPS develop disseminated intravenous coagulation (DIC), but, unlike the hantavirus-related hemorrhagic fevers (HFRS) seen in Asia, this is uncommon.

Proteinuria, and mild elevations of transaminases, CPK, amylase, and creatinine have also been reported.

When metabolic acidosis, prolongation of PT and PPT times and rising serum lactate levels develop, the prognosis is poor. Marked renal insufficiency has mainly been noted among cases from the southeastern United States although some degree of renal insufficiency, assessed by elevated serum creatinine levels, has been noted in 15% of all patients.

The combination of atypical lymphocytes, a significant bandemia, and thrombocytopenia in the setting of pulmonary edema is strongly suggestive of a hantavirus infection.

About the Author

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The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.