We’ve included the survey as well as the correct answers. In some cases where there is strong debate, both yes and no have been checked. There was also an option to select "unsure" as an answer which is omitted in this review.

Which of the following signs, symptoms and physical findings would you expect to encounter in most cases of HPS?

Individuals with HPS usually present with fever (>100^oF), dizziness, myalgia, headache, dyspnea, nausea and vomiting, and abdominal pain. Upon physical examination the individual’s respirations and heart rate are usually increased with corresponding decrease in blood pressure. With chest auscultation, diffuse crackles may be heard. Usually the illness has only been present for a short period of time (2-3 days).

A majority of health care providers answered the questions regarding signs, symptoms, and physical findings along the same lines as the panel of "experts". The only significant difference (p<0.001) was the answer for expiratory wheezing given by health care providers who have and have not seen HPS cases. Providers who have seen cases recognized that expiratory wheezing was not a physical finding seen with HPS.

In the patient’s history, which of the following would make you strongly consider HPS?

Because initial laboratory, radiologic, and physical examinations lack the specificity to diagnose HPS, the taking of a thorough history may be extremely helpful to the clinician dealing with a possible case. Individuals who have had rodent contact, especially deer mice, or who have been involved in outdoor or agricultural activities are at increased risk for infection with hantavirus. Also living in a rural area increases the individual’s risk as does living in a trailer or mobile home. Travel to the Four Corners area may increase one’s risk of developing HPS depending on the activities one engages in while in the area.

The "correct" answers were provided by the majority of health care providers.

What laboratory or radiographic abnormalities are commonly associated with HPS?

In evaluating an individual for HPS, it should be remembered that the only way to diagnose the disease is through specific testing for either the virus (PCR, immunohistochemical) or antibody (ELISA, Western Blot). On CBC testing, the patient would be expected to have a leukocytosis with a left shift, hemoconcentration, and thrombocytopenia. The clinician should especially watch for a thrombocyte count of less than 150,000, a finding that appears to be consistent in nearly all victims of the disease. With serum chemistry, the typical patient has an increase in serum lactate, LDH and other liver enzymes, and possible elevation in CPK. Decreases in serum bicarbonate and albumin would be expected. On examination of the urine, protein levels would be expected to be increased. Upon radiologic examination of the chest, bilateral interstitial infiltrates are the most likely abnormality to be seen. Other changes would be the presence of Kerley B lines and pleural effusions.

Between 50 to 80% of the respondents answered "not sure" on the questions for this section. A slight majority (less than 1%) indicated that patients with HPS do not present with hypoalbuminemia, which is incorrect. Three times as many respondents answered that HPS causes an increase in BUN/Creatine, which is also incorrect. On radiography, the majority of the respondents indicated they expected to observe signs of lower lobe infiltrates and no Kerley B lines; actually the reverse should be seen. Significant differences in the answers from providers who have seen HPS patients and those who have not were in the questions asking about a leukocytosis with a left shift, thrombocytopenia, decrease bicarbonate, elevated serum lactate, and hypoalbumnemia.

What is the currently accepted pathophysiologic mechanism of HPS?

Pathophysiologically, pulmonary capillary leakage is the hallmark sign of the presence of this disease. The lung fills with plasma from the capillary causing a decrease in the serum albumin levels and a whitening of the lung field on the chest film. The pathology responsible for most of the fatal outcomes is a myocardial depression that can result in cardiac arrest.

Early management of patient with suspected (unconfirmed) HPS should include (in the first 4 hours):

The majority of these cases will present to health care providers in rural hospitals or clinics. The early management of HPS in some cases can determine outcome. If HPS is suspected, no case should be sent home no matter how mild the symptoms and if possible the patient should be transferred to a tertiary care facility. Victims of HPS should be intubated early to provide respiratory support and blood pressure should be supported with inotropic medication and restricted fluids. Initially the patient should be started on broad spectrum antibiotics until a more specific diagnosis of HPS can be obtained.

Ongoing management of patient with HPS should include:

Management of HPS patients in the ICU setting includes continuous EKG monitoring and pulse oximetry in addition to continued monitoring of the hemodynamic profile to guide usage of IV fluid and inotropic medications. Thoracentesis is used to remove any pleural fluid.

We would like to thank all those who responded to our survey. For more information concerning HPS or hantavirus disease please call your local health department or the Utah Department of Health, Bureau of Epidemiology at (801) 538-6191. A New Hantavirus and Preventing Hantavirus Disease videos can be ordered through our office. Additional information can be obtained through the Centers for Disease Control and Prevention (CDC) web site at www.cdc.gov.

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The Epidemiology Newsletter is published monthly by the Utah Department of Health, Division of Epidemiology and Laboratory Services, Bureau of Epidemiology, to disseminate epidemiologic information to the health care professional and the general public.