Swine Influenza A (H1N1) Virus part 2

Treatment Recommendations

Treatment is largely supportive and consists of bedrest, increased fluid consumption, cough suppressants, and antipyretics and analgesics (eg, acetaminophen, nonsteroidal anti-inflammatory drugs) for fever and myalgias. Severe cases may require intravenous hydration and other supportive measures. Antiviral agents may also be considered for treatment or prophylaxis (see Medications).

Patients should be encouraged to stay home if they become ill, to avoid close contact with people who are sick, to wash their hands often, and to avoid touching their eyes, nose, and mouth. The CDC recommend the following actions when human infection with swine flu is confirmed in a community:6

Home isolation

Patients who develop flulike illness (ie, fever with either cough or sore throat) should be strongly encouraged to self-isolate in their home for 7 days after the onset of illness or at least 24 hours after symptoms have resolved, whichever is longer.
To seek medical care, patient should contact their health care providers to report illness (by telephone or other remote means) before seeking care at a clinic, physician’s office, or hospital.
Patients who have difficulty breathing or shortness of breath or who are believed to be severely ill should seek immediate medical attention.
If the patient must go into the community (eg, to seek medical care), he or she should wear a face mask to reduce the risk of spreading the virus in the community when coughing, sneezing, talking, or breathing. If a face mask is unavailable, ill persons who need to go into the community should use tissues to cover their mouth and nose while coughing.
While in home isolation, patients and other household members should be given infection control instructions, including frequent hand washing with soap and water. Use alcohol-based hand gels (containing at least 60% alcohol) when soap and water are not available and hands are not visibly dirty. Patients with swine influenza should wear a face mask when within 6 feet of others at home.
Household contacts who are not ill

Remain home at the earliest sign of illness.
Minimize contact in the community to the extent possible.
Designate a single household family member as caregiver for the patient to minimize interactions with asymptomatic persons.
School dismissal and childcare facility closure

Strong consideration should be given to close schools upon a confirmed case of swine flu or a suspected case epidemiologically linked to a confirmed case.
Decisions regarding broader school dismissal within these communities should be left to local authorities, taking into account the extent of influenzalike illness within the community.
Cancelation of all school or childcare related gatherings should also be announced.
Encourage parents and students to avoid congregating outside of the school if school is canceled.
Duration of schools and childcare facilities closings should be evaluated on an ongoing basis depending on epidemiological findings.
Consultation with local or state health departments is essential for guidance concerning when to reopen schools. If no additional confirmed or suspected cases are identified among students (or school-based personnel) for a period of 7 days, schools may consider reopening.
Schools and childcare facilities in unaffected areas should begin preparation for possible school closure.
Social distancing

Large gatherings linked to settings or institutions with laboratory-confirmed cases should be canceled (eg, sporting events or concerts linked to a school with cases); other large gatherings in the community may not need to be canceled at this time.
Additional social distancing measures are currently not recommended.
Persons with underlying medical conditions who are at high risk for complications of influenza should consider avoiding large gatherings.
Patient education

Patients should be referred to the eMedicine Health article Swine Flu.

Medications

Laboratory testing has found the swine influenza A (H1N1) virus susceptible to the prescription antiviral drugs oseltamivir and zanamivir, and the CDC has issued interim guidance for the use of these drugs to treat and prevent infection with swine influenza viruses.7 As part of its preparation for the emergency, the US Department of Homeland Security is releasing 25% of stockpiled antiviral agents (ie, oseltamivir [Tamiflu], zanamivir [Relenza]).

The usual vaccine for influenza administered at the beginning of the flu season is not effective for this viral strain. Also, other antiviral agents (eg, amantadine, rimantadine) are not recommended because of recent resistance to other influenza strains documented over the past several years.

Basic supportive care (ie, hydration, analgesics, cough suppressants) should be prescribed. Empiric antiviral treatment should be considered for confirmed, probable, or suspected cases of swine influenza. Treatment of hospitalized patients and patients at higher risk for influenza complications should be prioritized.

Initiation of antiviral agents within 48 hours of symptom onset is imperative for providing treatment efficacy against influenza virus. In studies of seasonal influenza, evidence for benefits of treatment is strongest when treatment is started within 48 hours of illness onset. However, some studies of treatment of seasonal influenza have indicated benefit, including reductions in mortality or duration of hospitalization, even in patients in whom treatment was started more than 48 hours after illness onset. The recommended duration of treatment is 5 days.7

Prophylaxis with antiviral agents should also be considered in the following individuals (pre-exposure or postexposure):
Close household contacts of a confirmed or suspected case who are at high risk for complications (eg, chronic medical conditions, persons >65 y or <5 y, pregnant women)
School children at high risk for complications who have been in close contact with a confirmed or suspected case
Travelers to Mexico who are at high risk for complications (eg, chronic medical conditions, persons >65 y or <5 y, pregnant women)
Health care providers or public health workers who were not using appropriate personal protective equipment during close contact with a confirmed or suspected case
Pre-exposure prophylaxis can be considered in the following persons:
Any health care provider who is at high risk for complications (eg, chronic medical conditions, adults >65 y, pregnant women)
Individuals not considered to be at high risk but who are nonetheless traveling to Mexico, first responders, or border workers who are working in areas with confirmed cases
Antiviral Agents

Drugs indicated for treatment of swine influenza A (H1N1) virus include neuraminidase inhibitors (ie, oseltamivir and zanamivir).

Oseltamivir (Tamiflu)

Oseltamivir inhibits neuraminidase, which is a glycoprotein on the surface of influenza virus that destroys an infected cell's receptor for viral hemagglutinin. By inhibiting viral neuraminidase, this agent decreases the release of viruses from infected cells and, thus, viral spread. Oseltamivir is effective in the treatment of influenza A or B and must be administered within 48 hours of symptom onset. The sooner the drug is administered after symptom onset, the better the likelihood of a good outcome. Oseltamivir reduces the length of illness by an average of 1.5 days. (In a subgroup of high-risk patients, illness was reduced by 2.5 d.) In addition, the severity of symptoms is also reduced.

Oseltamivir is available as 30-mg, 45-mg, and 75-mg oral capsules and as a powder for suspension that contains 12 mg/mL after reconstitution.

Adult dose
Treatment for acute illness: 75 mg PO bid for 5 d
Prophylaxis: 75 mg PO qd
Pediatric dose
Treatment for acute illness and age <1 year
<3 months: 12 mg PO bid
3-5 months: 20 mg PO bid
6-11 months: 25 mg PO bid
Treatment for acute illness and age >1 year
<15 kg: 30 mg PO bid
15-23 kg: 45 mg PO bid
23-40 kg: 60 mg PO bid
>40 kg: Administer as in adults
Prophylaxis and age <1 year
<3 months: Data limited; not recommended unless situation judged critical
3-5 months: 20 mg PO qd
6-11 months: 25 mg PO qd
Prophylaxis and age >1 year
<15 kg: 30 mg PO qd
15-23 kg: 45 mg PO qd
23-40 kg: 60 mg PO qd
>40 kg: Administer as in adults
Zanamivir (Relenza)

Zanamivir inhibits neuraminidase, which is a glycoprotein on the surface of the influenza virus that destroys the infected cell's receptor for viral hemagglutinin. By inhibiting viral neuraminidase, release of viruses from infected cells and viral spread are decreased. Zanamivir is effective against both influenza A and B. The preparation of zanamivir is in powder form for inhalation via the Diskhaler oral inhalation device. Circular foil discs that contain 5-mg blisters of drug are inserted into the supplied inhalation device. Individuals with asthma or other respiratory conditions that may decrease ability to inhale drug should be given oseltamivir.

Adult dose
Treatment for acute illness: 10 mg inhaled orally bid for 5 d
Prophylaxis of household contact: 10 mg inhaled orally qd for 10 d (initiate within 36 h)
Prophylaxis for community outbreak: 10 mg inhaled orally qd for 28 d (initiate within 5 d of outbreak)
Pediatric dose
Treatment for acute illness
<7 years: Not established
>7 years: Administer as in adults
Prophylaxis in household contact
<5 years: Not established
>5 years: Administer as in adults
Prophylaxis in community outbreak
Adolescents 12-16 years: Administer as in adults
Additional pediatric considerations

Aspirin or aspirin-containing products (eg, bismuth subsalicylate [Pepto Bismol]) should not be included in the treatment of confirmed or suspected viral infection in persons aged 18 years or younger because of the risk of Reye syndrome. For relief of fever, other antipyretic medications (eg, acetaminophen, nonsteroidal anti-inflammatory drugs) are recommended.

Pregnant women

Oseltamivir and zanamivir are "Pregnancy Category C" medications, indicating that no clinical studies have been conducted to assess the safety of these medications in pregnant women. Because of the unknown effects of influenza antiviral drugs on pregnant women and their fetuses, oseltamivir or zanamivir should be used during pregnancy only if the potential benefit justifies the potential risk to the embryo or fetus; the manufacturers' package inserts should be consulted. However, no adverse effects have been reported among women who received oseltamivir or zanamivir during pregnancy or among infants born to women who have received oseltamivir or zanamivir. Pregnancy should not be considered a contraindication to oseltamivir or zanamivir use. Because zanamivir is an inhaled medication and has less systemic absorption, some experts prefer zanamivir over oseltamivir for use in pregnant women, when feasible.7

Multimedia


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Media file 1: Swine influenza virus. Colorized transmission electron micrograph (37,800X) of the A/New Jersey/76 (Hsw1N1) virus under plate magnification. Image taken during the virus' first developmental passage through a chicken egg. Courtesy of the CDC/Dr. E. Palmer; R.E. Bates.

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Media file 2: Phase 4 is characterized by verified human-to-human transmission of an animal or human-animal influenza reassortant virus able to cause "community-level outbreaks." The ability to cause sustained disease outbreaks in a community marks a significant upwards shift in the risk for a pandemic. Any country that suspects or has verified such an event should urgently consult with WHO so that the situation can be jointly assessed and a decision made by the affected country if implementation of a rapid pandemic containment operation is warranted. Phase 4 indicates a significant increase in risk of a pandemic but does not necessarily mean that a pandemic is a forgone conclusion. Courtesy of the WHO.

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Media file 3: Negative stained transmission electron micrograph of recreated 1918 influenza virions. Courtesy of CDC/ Dr. Terrence Tumpey.

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Media file 4: This preliminary negative stained transmission electron micrograph depicts some of the ultrastructural morphology of the A/CA/4/09 swine flu virus. Courtesy of CDC/ C. S. Goldsmith and A. Balish.

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Media file 5: This preliminary negative stained transmission electron micrograph depicts some of the ultrastructural morphology of the A/CA/4/09 swine flu virus. Courtesy of CDC/ C. S. Goldsmith and A. Balish.
Keywords

swine flu, swine influenza, swine influenza virus, swine influenza A (H1N1) virus, human swine flu, influenza A, influenza (H1N1), swine flu symptoms, swine flu diagnosis, swine flu treatment, swine flu antiviral, swine flu pandemic