Swine Flu

A client of mine was asking about swine flu and tamiflu.
This article for doctors might be useful for you at this worrisome time.

Swine Flu: Guidance and Resources for Clinicians

Susan B. Yox, RN, EdD
Published: 04/28/2009

Swine influenza is a highly contagious respiratory disease of pigs caused by one of several swine influenza A viruses. Outbreaks are common in pigs year-round, but infection in humans historically is a result of close contact with infected animals. This current virus is a novel influenza A virus, more properly termed a new subtype of influenza A (H1N1) that was not previously detected in swine or humans. More important is that this new strain appears to be spread by human-to-human transmission.

It is likely that most people, particularly those who do not have regular contact with pigs, do not have any immunity to swine influenza viruses. Thus the concern is that if efficient human-to-human transmission is established, a pandemic is possible.

Government and public health officials are monitoring this situation worldwide to assess the threat from swine flu and to provide guidance to healthcare professionals and the public. Because the situation is changing rapidly, it is important to check regularly for changes in recommendations as new information becomes available.

This article is based on guidance and resources available from both the United States Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO); they have been summarized here with the objective of offering practicing clinicians a one-stop resource for clinical practice concerns related to swine flu.

What Is the Clinical Presentation of Swine Flu?

Persons infected with swine flu may appear similar to those with seasonal influenza, presenting with symptoms of acute respiratory illness. Symptoms include at least 2 of the following:

Rhinorrhea or nasal congestion;
Sore throat;
Cough; and
Fever.
In addition, persons with swine flu may have other typical symptoms of influenza, including body aches, headache, chills, fatigue, and possibly diarrhea and vomiting.

Who Is Most at Risk for Swine Flu?
The CDC recommends that clinicians particularly consider the possibility of swine influenza A (H1N1) virus infection in patients with fevers and respiratory symptoms who:

1.Live in areas in the United States with confirmed human cases of swine influenza A (H1N1) virus infection. (To find the most up-to-date information on areas with confirmed swine influenza cases, go to http://www.cdc.gov/swineflu/index.htm)
2.Traveled recently to Mexico or were in contact with persons who had febrile respiratory illness and were in areas of the United States with confirmed swine influenza cases or Mexico in the 7 days preceding illness onset.
3.In addition, a person with an acute respiratory illness who has a recent history of contact with an animal with confirmed swine influenza should also be suspected (http://www.cdc.gov/swineflu/recommendations.htm).

What Is the Range of Illness Severity Seen With Swine Flu?
Many cases of swine flu may be mild or even asymptomatic. In the past, cases were identified by chance as part of regular seasonal influenza surveillance. Most of the recent cases seen in the United States thus far have been mild as well.
However, in Mexico, many patients' illnesses have been much more severe, have presented in young adults, and have included pneumonia, respiratory failure, and acute respiratory distress syndrome. Illness-related fatalities have been recorded in Mexico. At this time, it is not clear why such differences in illness severity have been seen. Early in epidemics it is difficult to gauge severity because the overall denominator of people infected is unknown.

How Should Swine Flu Be Diagnosed?
Preferred specimens. If swine flu is suspected, clinicians should obtain a respiratory specimen for analysis. In an ideal situation, the best method is via nasal pharyngeal aspirate or nasal wash aspirate into viral culture media; however, some experts are recommending the use of Dacron nasal swabs to decrease aerosolization of the virus. If these specimens cannot be collected, a combined nasal swab with an oropharyngeal swab is also acceptable and will be feasible in most settings. (Ideally, swab specimens should be collected using swabs with a synthetic tip and an aluminum or plastic shaft. Swabs with cotton tips and wooden shafts are not recommended. Specimens collected with swabs made of calcium alginate are not acceptable.)

The specimen should be placed in a 4°C refrigerator (not a freezer) or immediately placed on ice or cold packs for transport to the laboratory. Once collected, make contact with the state or local health department to facilitate transport and timely diagnosis at a state public health laboratory.

Recommended tests. The CDC currently recommends "real-time RT-PCR for influenza A, B, H1, H3 conducted at a State Health Department Laboratory. Currently, swine influenza A (H1N1) virus will test positive for influenza A and negative for H1 and H3 by real-time RT-PCR. If reactivity of real-time RT-PCR for influenza A is strong (e.g., Ct ≤ 30) it is more suggestive of a novel influenza A virus." Confirmation as swine influenza A (H1N1) virus is now performed at the CDC but may be available in state public health laboratories soon.

Rapid influenza testing. Rapid testing for swine flu likely is similar to that for seasonal flu, meaning that sensitivities range between 50% and 70% of cases (no better than using fever and cough as a marker in a patient during influenza season), depending on the manufacturer. Therefore, negative rapid tests should not indicate a lack of influenza. (For general guidance on rapid influenza testing, see http://www.cdc.gov/flu/professionals/diagnosis/rapidlab.htm)

Rapid tests can distinguish between influenza A and B viruses. A patient with a positive rapid test for influenza A may meet criteria for a probable case of swine flu, but again, a negative rapid test could be a false negative and should not be assumed a final diagnostic test for swine influenza infection.

Other tests. Immunofluorescence (DFA or IFA) tests can distinguish between influenza A and B viruses. A patient who is positive for influenza A by immunofluorescence may meet criteria for a probable case of swine influenza. However, a negative immunofluorescence could be a false negative and should not be assumed a final diagnostic test for swine influenza infection.

Isolation of swine influenza A (H1N1) virus by viral culture is also diagnostic of infection but may not yield timely results for clinical management. A negative viral culture does not exclude infection with swine influenza A (H1N1) virus.

To stay up-to-date on the latest recommendations for testing, check regularly at: http://www.cdc.gov/swineflu/specimencollection.htm

How Can Swine Flu Be Treated?
According to the CDC, swine influenza A (H1N1) is susceptible to the neuraminidase inhibitor antiviral medications zanamivir and oseltamivir. It is resistant to amantadine and rimantadine (http://www.cdc.gov/swineflu/recommendations.htm).

Treatment recommendations are as follows:

Suspected cases: Treat with zanamivir alone or with a combination of oseltamivir and either amantadine or rimantadine as soon as possible after the onset of symptoms and for a duration of 5 days.
Confirmed cases: Zanamivir or oseltamivir should be administered for 5 days.
Pregnant women: Antiviral medications are in Pregnancy Category C, so they should be used during pregnancy only if the potential benefit outweighs the potential risk to the embryo or fetus.
Children younger than 1 year: Because infants typically have high rates of morbidity and mortality from influenza, infants with swine influenza A (H1N1) infections may benefit from treatment with oseltamivir.
Detailed guidance on antiviral treatment for swine flu may be found here: http://www.cdc.gov/swineflu/recommendations.htm

Should Antiviral Chemoprophylaxis Be Considered for Specific Populations?
Chemoprophylaxis is recommended for 7 days after the last known exposure to a confirmed case of swine influenza A (H1N1) virus. See http://www.cdc.gov/flu/professionals/antivirals/dosagetable.htm#table for dosing and schedules.

The CDC recommends that the following populations receive chemoprophylaxis:
1.Household close contacts of a confirmed or suspected case who are at high risk for complications of influenza (persons with certain chronic medical conditions, elderly).
2.School children who are at high risk for complications of influenza (persons with certain chronic medical conditions) who have had close contact (face-to-face) with a confirmed or suspected case.
3.Travelers to Mexico who are at high risk for complications of influenza (persons with certain chronic medical conditions, elderly).
4.Border workers (Mexico) who are at high risk for complications of influenza (persons with certain chronic medical conditions, elderly).
5.Healthcare workers or public health workers who have had unprotected close contact with a person with confirmed swine influenza A (H1N1) virus infection during the infectious period. (Detailed guidance on this topic is available at http://www.cdc.gov/swineflu/recommendations.htm)

For How Long Is Swine Flu Contagious?
Persons with swine flu are considered infectious for 1 day before onset of the illness to 7 days after the onset.

What Infection-Control Precautions Should Be Taken in Healthcare Settings?
Patients who have a suspected or confirmed case of swine flu and who need to be hospitalized should be placed in a single-patient room with the door kept closed. The patient should wear a mask when outside the room. Standard, droplet, and contact precautions should be implemented and maintained by healthcare professionals for 7 days after the illness onset or until symptoms have resolved (http://www.cdc.gov/swineflu/guidelines_infection_control.htm).

source :http://www.medscape.com/viewarticle/702050?sssdmh=dm1.464966&src=ddd