Hantavirus
Hantavirus: Excerpt from The 5-Minute Pediatric Consult
Bruce Tempest, MDJonathan Iralu, MD
Hantavirus - BASICS
Hantavirus - description
Hantavirus pulmonary syndrome (HPS) is a disease in humans owing to a Hantavirus; it is acquired from certain chronically infected rodent species. When acquired by humans, it results in a syndrome characterized by a flulike illness, then by a rapidly progressive cardiac and respiratory failure with a high mortality.
Hantavirus - general prevention
- Universal precautions are appropriate in caring for patients with hantavirus pulmonary syndrome; person-to-person transmission has been demonstrated only with the Andes strain in the Southern Hemisphere, not in the US.
- Preventing infection depends on avoiding contact with airborne particles contaminated by rodent excreta.
- Eliminate rodents and seal off rodent access into the house.
- Reduce rodent shelter and food sources in the immediate vicinity of the home by cutting brush, removing trash, and storing grain and animal feed in rodent-proof containers.
- Wearing gloves, clean up rodent-contaminated areas by spraying nests and droppings with household disinfectants or dilute bleach, and sealing material in bags for burning or burial.
- Ventilate closed areas before initiating cleanup.
Hantavirus - epidemiology
- The host rodent develops a chronic nonfatal infection and excretes virus in urine, feces, and saliva.
- Humans acquire the infection by inhaling virus-contaminated airborne particles from the dried rodent excreta. Typically, this occurs when sweeping or otherwise disturbing dusty areas in a rodent-infested building.
- Nosocomial transmission has been observed only with the Andes strain in Argentina, never in the US.
- In the US, hantavirus pulmonary syndrome has occurred primarily in young healthy adults, although in South America a larger proportion of cases are in children.
Hantavirus - incidence
Human cases are more common in the spring and summer and also in years when the population of the rodent host has increased.
Hantavirus - pathophysiology
- The 2 most important pathophysiologic changes:
- Myocardial depression resulting in shock
- The cardiac dysfunction is characterized by a falling cardiac output, increased systemic vascular resistance, and normal or low pulmonary artery wedge pressure.
- Alveolar capillary leak pulmonary edema resulting in hypoxia
- The pulmonary alveoli are flooded with fluid devoid of erythrocytes but with a protein content similar to serum.
Hantavirus - etiology
The original human outbreak recognized in the southwestern US was caused by the Sin Nombre strain of Hantavirus transmitted from chronically infected deer mice (Peromyscus maniculatus). Subsequent cases were recognized throughout the seemingly ubiquitous distribution of the deer mouse. Since then, additional strains of Hantavirus have been recognized, each with a unique rodent host. The resulting human cases of hantavirus pulmonary syndrome have now been identified from Canada to Argentina.
Hantavirus - DIAGNOSIS
Pitfalls:
- Recognizing the prodrome of hantavirus pulmonary syndrome is difficult and requires a careful history, evaluation of the risk of exposure, and rapid access to testing:
- The diagnosis depends on serologic testing, which can take some time.
- Lacking serologic confirmation, one mostly depends on clinical history and serial hematologic tests.
- In anticipation of the rapid progression of the cardiopulmonary phase, it is preferable to have the patient closely observed in the hospital.
Hantavirus - signs & symptoms
Hantavirus - history
Clinical symptoms, physical findings, and laboratory findings progress in sequence. Early suspicion of the syndrome allows the clinician to prepare for that phase of the illness characterized by the rapid onset of respiratory failure and shock:
- Fever and myalgia are usually severe and characterize the prodromal phase lasting 3–6 days.
- Gastrointestinal complaints are frequently prominent, including combinations of nausea, vomiting, diarrhea, or abdominal pain.
- Headache is present in >50% of patients.
- Cough is uncommon at the onset of the prodrome, but heralds the onset of dyspnea and tachypnea, which is then followed by the rapid progression of cardiorespiratory failure.
- Coryza and sore throat are rarely part of the prodrome.
- A history of activities that might expose the patient to airborne virus-contaminated particles should be sought:
- Hantavirus pulmonary syndrome is acquired by inhalation on airborne particles.
Hantavirus - physical exam
- Tachycardia and hypotension are late findings.
- During the prodromal phase, fever is the only finding.
- With the onset of the cardiopulmonary phase, cough and dyspnea are associated with the production of frequently copious amounts of nonpurulent material.
Hantavirus - tests
Hantavirus - lab
- Platelet count:
- The platelet count falls on serial testing during the prodromal phase and may be the only abnormality measurable using laboratory methods.
- In addition to leukocytosis, myelocytes and immunoblasts appear in the peripheral blood.
- Liver function test results are only mildly abnormal.
- Hypoxemia accompanies the onset of the cardiopulmonary phase.
- Diagnostic serology demonstrates IgM antibody present at the time of clinical presentation.
Hantavirus - imaging
Chest radiograph:
- During the prodrome, chest radiography is normal. With the onset of cardiopulmonary symptoms, chest radiography will show evidence of interstitial fluid manifested by Kerley B lines, hilar indistinctness, and peribronchial cuffing. Alveolar flooding and pleural effusions develop in severe cases. Heart size remains normal.
Hantavirus - differencial diagnosis
- Septicemic plague
- Influenza
- Bacterial sepsis, especially that caused by Pneumococcus and other streptococci
- Other causes of shock and pneumonia or shock and pulmonary edema
Hantavirus - TREATMENT
Hantavirus - special therapy
Because of the rapid progression of cardiorespiratory failure, all patients with hantavirus pulmonary syndrome should be managed in an ICU setting with a pulmonary artery catheter to guide therapy:
- Oxygen, intubation, and mechanical ventilation are frequently needed.
- Use fluids cautiously in view of the capillary leak.
- Extracorporeal membrane oxygenation has been used for patients who fail to respond to maximal inotropic and ventilatory support.
- To date, antiviral agents have not been shown to be beneficial.
Hantavirus - medication
- If the patient develops hypotension, an inotropic agent such as dobutamine should be added; if the patient continues to be hypotensive on maximal doses of dobutamine, vasopressors can be added to maintain BP.
- Use empiric antibiotics because serologic tests confirming hantavirus pulmonary syndrome are usually delayed and the differential diagnosis includes sepsis from a variety of antibiotic-responsive organisms.
Hantavirus - FOLLOW UP
Hantavirus - prognosis
- Patients who survive the shock phase typically diurese fluid. Recovery is then generally rapid.
- Easy fatigability and mild pulmonary function abnormalities may persist.
Hantavirus - bibliography
All About Hantavirus Web page: http://www.cdc.gov/ ncidod/diseases/hanta/hps/index.htm.- Butler JC, Peters CJ. Hantaviruses and hantavirus pulmonary syndrome. Clin Infect Dis. 1994;19:387–395.
- Duchin JS, et al. Hantavirus pulmonary syndrome: A clinical description of 17 patients with a newly recognized disease. N Engl J Med. 1994;330:949–955.
- Graziano KL, Tempest B. Hantavirus pulmonary syndrome: A zebra worth knowing. Am Fam Physician. 2002;66:1015–1020.
- Hallin GW, et al. Cardiopulmonary manifestations of hantavirus pulmonary syndrome. Crit Care Med. 1996;24:252–258.
- Khan AS, Young JC. Hantavirus pulmonary syndrome: At the crossroads. Curr Opin Infect Dis. 2001;14:205–209.
- Ferres M, Vial P. Hantavirus infection in children. Curr Opin Pediatr. 2004;16(1):70–75.
Hantavirus - CODES
Hantavirus - icd9
079.81 Hanta virus
Hantavirus - FAQ
- Q: What should I do if I find a dead mouse indoors?
- A: Determine whether it is a house mouse or a species that could be infected with Hantavirus. If the latter, assume that it is infected and dispose of it as described previously and then seal off rodent access to the home and eliminate any individuals still left inside.
- Q: What should I do if I find what look like rodent droppings?
- A: Clean up with gloves and disinfectant as noted earlier. Then use traps to catch and identify the rodents involved and proceed as in the answer to the previous question.
- Q: Could a patient have hantavirus pulmonary syndrome without knowing it?
- A: In the US, asymptotic hantavirus pulmonary syndrome infections would appear to be uncommon based on serum screening of household contacts of cases and other populations at high risk, which show only infrequent evidence of prior infection.
Book Source Details
- Book Title: The 5-Minute Pediatric Consult
- Author(s): M. William Schwartz MD; et al.
- Year of Publication: 2008
- Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.
More About Hantavirus
More Medical Textbooks Online about Hantavirus
Review other book chapters online related to Hantavirus:
Medical Books Excerpts
- Epigastric Distress
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
|
|
More About This Book:
Title: The 5-Minute Pediatric Consult
Authors: M. William Schwartz MD; et al.
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7577-9
|
|
» Next page:
Surveys relating to Hantavirus
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
