Swine Flu Antiviral Treatment with Medicines
Medications Used to Prevent and Treat Swine-Origin Influenza A H1N1
May 3, 2009
There is widespread panic among the public about swine flu. Knowledge of the infection and measures to prevent, detect and treat swine flu are important to allay concerns.
Swine influenza is spread the same way other upper respiratory infections are spread: through respiratory droplets. Frequent hand washing, avoiding touching your eyes, mouth and nose, decreases chances of contracting this illness. Respiratory droplets can be coughed or sneezed up to six feet. People who are ill with infections should stay out of work or school to prevent further spread.
Swine-origin influenza (S-OIV) is a hybrid strain of swine, human and avian (bird) influenza strains. Influenza strains are categorized by certain type of hemagglutinin (H) and neuraminidase (N) molecules present on the surface of virus particles. The current strain is H1N1. The 2008-2009 flu shot protected against certain strains of human influenza A and B viruses, but not the H1N1 strain.
Swine flu is not transmitted by eating contaminated pork. Furthermore, heating pork products to 160 degrees Fahrenheit kills swine flu and other dangerous microorganisms.
How is Swine-Origin Influenza Infection Detected?
Several different types of rapid tests exist which can detect Influenza A and B infections, including swine flu. A nasal swab, aspirate or washing should be obtained in a clinic or hospital setting. The accuracy of the rapid tests is highly variable and is less than 100%. The rapid tests are more likely to yield false negative results than false positive test results. The clinical picture must be taken into account when interpreting a rapid influenza test result.
A nasal sample sent to the Centers for Disease Control can confirm the diagnosis of H1N1 swine flu with one of two tests. One test is called the Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR). The second test is actual culture of the H1N1 strain of swine-origin influenza. Random testing done on healthy individuals to provide reassurance will tax the already overburdened public health departments.
Anti-Viral Treatment of Swine Influenza A H1N1
A high index of suspicion must be maintained for influenza in patients with fever, malaise, cough, sore throat and body aches. Patients with obvious cold symptoms should not be automatically treated for swine flu, as this indiscriminate treatment can promote the growth of resistant strains of swine flu.
If a physician recommends treatment with antiviral medication to treat swine flu, two medications are available.
- In patients age 1 year and older, oseltamivir (brand name Tamiflu ®) is approved to both treat and prevent influenza A and B virus infection, including swine flu H1N1. It is a neuraminidase inhibitor. Recently, the Food and Drug Administration has approved the use of oseltamavir in infants under the age of 1 by an Emergency Use Authorization (EUA).
- Zanamivir (brand name Relenza ®) is approved to treat influenza A and B virus infection in people 7 years and older. In patients 5 years and older, it can be used to prevent influenza A and B virus infection. This medication is inhaled.
Note that many strains of the 2008-2009 influenza season were resistant to olseltamivir and zanamivir, but sensitive to the older anti-influenza agents amantadine and rimantadine. Swine flu H1N1 is resistant to the anti-influenza medications amantadine and rimantadine.
Post-Exposure Preventative Treatment with Anti-Viral Medicines
Close household contacts of a person who has confirmed swine flu infection should be treated with oseltamivir or zanamavir if there is a high risk of developing serious complications of influenza. Prophylactic (preventative) treatment with anti-viral medications should extend for seven days from the last known exposure.
High risk individuals include pregnant women, people over the age of 65, children under the age of 5 and patients with certain chronic medical problems such as underlying lung disease. Health care workers who did not have protective equipment during exposure to a patient with swine flu should also receive preventative treatment.
Close contacts need to be quarantined for seven days to prevent spread of infection. Patients with swine flu are contagious from one day prior to symptoms to seven days after the start of symptoms.
Precautions for Anti-Viral Medications
The most common side effect of oseltamavir was nausea and vomiting. It is therefore recommended that the medicine be taken with food. Rare cases of serious skin reactions, including life threatening reactions involving mouth ulcers and sloughing of large areas of skin on the body have been reported. Rare life threatening allergic reactions have also been reported.
There have also been cases of delirium , hallucinations, confusion and self-injury, primarily in Japanese children who received oseltamivir and zanamavir. However, it is not clear if these symptoms were directly caused by the neuraminidase inhibitors. The U.S. Food and Drug Administration (FDA) and the manufacturers of olestamivir and zanamavir have issued a "Dear Health care Professional letter" to warn of these possible side effects on the brain. It is recommended that these medications only be used under the supervision of a physician.
The Centers for Disease Control has released emergency stockpiles of anti-viral influenza medications.
Oseltamivir and zanamivir are "Pregnancy Category C" medications, meaning that clinical studies have not been done to see if these medications are safe for use during pregnancy. However, they have been used in pregnant women when the benefits of treatment with oseltamivir and zanamavir outweigh the risks. Consult your physician before taking any anti-viral influenza medication.
Reference:
Centers for Disease Control Information on Swine-Origin Influenza
Legal Disclaimer:
This article is for informational purposes only and should not substitute for medical advice from your health care provider. The author is not providing personal medical opinion, diagnosis or course of treatment. Do not delay or substitute this information for medical treatment.
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