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Hantavirus Pulmonary Syndrome

Introduction

Hantavirus Pulmonary Syndrome is caused by the hantavirus, which is a virus transmitted by deer mice.

Even though sporadic cases have been reported in 1959, it was only in 1996 that this syndrome was renewed detected in the US as there were more than 100 cases reported west of the Mississippi River (Ref. 6, p. 1310). The mode of transmission is by inhalation of protein particles from dried up urine from mice in cottages, houses or warehouses infested with mice.

Farm and timber workers are at a higher risk. There are now several subtypes of hantaviruses known. One of the lesser virulent types causes hemorrhagic fever with renal syndrome (also called “Korean hemorrhagic fever”). In this form of hantavirus illness the mortality rate is only about 10%, whereas with hantavirus pulmonary syndrome the mortality rate is around 60%to 70%!

Signs and symptoms

Children are rarely affected by this disease, which is poorly understood. Most patients are preteen to senior age group. There is an acute onset with fever, vomiting, abdominal pain, headaches and muscle aches. The disease then affects the lungs with fluid accumulation (acute pulmonary edema) coupled with low blood pressure and shock. There can be bleeding into the conjunctiva of the eyes (=the white of the eyes) or under the skin.

There is a huge discrepancy with mild cases improving within 1 week and with severe cases being sick for weeks or months. The more severe cases lead to bleeding problems on account of bone marrow depletion with low platelet counts and liver inflammation leading to a lack of clotting factor production.

This leads to massive fluid shifts and transient kidney failure, which can lead to life threatening conditions.

Diagnostic tests

There are non specific blood test findings with an increased WBC count, low platelet counts and circulating immature immune cells. Later in the disease there are elevated liver enzymes and high lactate levels in patients who do poorly. Specific serological tests will positively identify the hantavirus type.

Treatment

It is important to recognize the disease early as complications occur from shock and pulmonary failure leading to death. With early detection and early intubation in the Intensive Care Unit setting of a hospital combined with intravenous ribavirin therapy, an antiviral drug, mortality rates of 40% to 50% can be achieved when in the past the norm was 80% to 90% (Ref.7).

Treatment of this complex disease process with ever changing threats ranging from bone marrow failure, liver failure, kidney failure as well as congestive heart failure and pulmonary edema, which is very challenging, even to the most experienced physician team. It is hoped that research into finding the difference of the immune response between the poor and the good outcomes might shed light onto new treatment modalities. Also, a vaccination against hantavirus has already been developed for high risk professions (Ref. 8); this link indicates that a Korean vaccine is effective after three or more vaccinations have been given.

 

References:

1. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 161.

2. TC Dixon et al. N Engl J Med 1999 Sep 9;341(11):815-826.

3. F Charatan BMJ 2000 Oct 21;321(7267):980.

4. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse   Station, N.J., 1999. Chapter 43.

5. JR Zunt and CM Marra  Neurol Clinics Vol.17, No.4,1999: 675-689.

6. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse   Station, N.J., 1999. Chapter 162.

7. LE Chapman : Antivir Ther 1999; 4(4): 211-19.

8. HW Cho: Vaccine 1999 Jun 4; 17(20-21): 2569-2575.

9. DO Freedman et al. Med Clinics N. Amer. Vol.83, No 4 (July 1999):     865-883.

10. SP Fisher-Hoch et al. J Virol 2000 Aug; 74(15): 6777-6783.

11. Mandell: Principles and Practice of Infectious Diseases, 5th ed., ©   2000 Churchill Livingstone, Inc.

12. Goldman: Cecil Textbook of Medicine, 21st ed., Copyright © 2000   W. B. Saunders Company

13. PE Sax: Infect DisClinics of N America Vol.15, No 2 (June 2001):   433-455.

14. David Heymann, MD, Editor: Control of Communicable Diseases Manual, 18th Edition, 2004, American Public Health Association.

Last modified: October 20, 2014

Disclaimer
This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.