May 13, 2009
Novel Influenza A (H1N1) Update:
We are now in the middle of the third week of activity for this novel strain of influenza virus. Over the past two weeks, a number of things have become apparent:
- Disease activity in Mexico appears to have leveled off and even dropped (keep in mind that this virus had been circulating in Mexico since March 9, 2009).
- Disease activity in the United States is increasing daily with well over 3,000 documented cases to date, and disease activity in 44 states and the District of Columbia.
- Disease has spread beyond travelers to Mexico or their close contacts, meaning that secondary spread is now occurring. Illinois reports over 500 confirmed cases as of today.
- In the Dayton area, we (Dayton Children’s) have tested approximately 100 samples since May 1, and have not had a true positive for influenza A. We have had at least two false positives (we think). Seasonal influenza A is gone for the year, thus any true positive is likely to be the novel H1N1 strain.
- Tamiflu (25 percent of 50 million treatment courses) was released by the federal government to the states. We have been told that the local allotment was returned to Columbus for storage.
- CDC guidance continues to evolve on a daily basis (http://www.cdc.gov/).
- To date, the virulence of this virus seems to be similar to the strains that circulated this past winter; its transmissibility also seems to be similar to other strains.
- With increasing number of cases, there will be more hospitalizations and deaths (keep in mind that 35,000 people and 56 children died this past winter due to influenza related disease).
We have a core group of staff who are meeting regularly. We reaffirmed our decision to route all possible influenza A patients through the emergency department. If you wish to refer a suspect case, please give them a mask to wear and send them to our emergency room. A call to the communication center (937-641-4385) would be helpful. Once the patient arrives they will be evaluated in one of the negative pressure rooms and admitted to the PICU if admission is required. This allows us to use resources most efficiently, but presumes that the volume of admissions is relatively low. The emergency department, PICU, respiratory therapy staff and a core group of physicians have been fit-tested with the N-95 respirator masks, recommended for those in immediate contact with a suspected case. Thus we can provide good care while trying to limit exposure of the staff. If the number of cases grows to parallel the average winter outbreak, we will likely have to modify these plans. Given a conflict in recommendations for visitors by the WHO and the CDC, we have elected to allow visitation to immediate family members, while restricting access to those who are ill.
The CDC has recently issued a series of guidance statements that address a number of issues:
- Update on school (K through 12) and child care centers
- Breastfeeding your baby, what parents should know.
- Antiviral recommendations, including dosages of Tamiflu for infants. To date strains of H1N1 (68 tested) have been uniformly susceptible to Tamiflu but are resistant to amantadine.
- Clinical guidance for infants and young children.
- Infection control in a health care setting.
When asked about testing samples in a point of care lab, the CDC said “where it is not possible to use a biosafety cabinet, such as a physician’s office lab, then appropriate personal protective equipment (lab coat, gloves, masks, eye protection) should be worn when performing rapid flu testing”.
Finally, some comments regarding the treatment/prophylaxis of cases of novel influenza (H1N1). To date, there have been five reported deaths outside of Mexico, including three in the USA. One of the three was a toddler. All three had some underlying medical condition. The CDC recommends treatment for all hospitalized patients with confirmed, probable or suspect novel influenza. They also recommend treatment for those who are at “higher risk” for complications:
- Children younger than 5 years of age, but especially those younger than 2 years of age.
- Adults aged 65 and older.
- Persons with chronic pulmonary (includes asthma), cardiovascular (excludes hypertension), renal, hepatic, hematologic (includes sickle cell disease), neurologic, neuromuscular or metabolic diseases (includes diabetes).
- Immunosuppression: includes that caused by medications or HIV.
- Pregnant women.
- Persons under 19 years of age receiving long-term aspirin (children should also avoid drugs containing aspirin).
- Residents of nursing homes and chronic care facilities.
As far as prophylaxis is concerned, the CDC recommends antiviral prophylaxis be considered for:
- Close contacts of confirmed, probable or suspect cases who are at high risk for complications
- Health care personnel, health workers or first responders with a recognized, unprotected close contact exposure to a confirmed, probable or suspect case.
The challenge here is that the definitions of confirmed, probable or suspect are changing. As of 8:30 pm on May 11, 2009, the definitions (these are for the purpose of health department investigations) are as follows:
- Confirmed: person with an influenza-like illness (ILI) which includes fever with cough or sore throat, with laboratory confirmed novel influenza A (H1N1) infection by real time RT-PCR (ODH or CDC) or positive viral culture.
- Probable: person with ILI who is positive for influenza A, but negative for H1 and H3 by influenza RT-PCR.
- Suspect: a person who does not meet the confirmed or probable case definition, and is not novel H1N1 test negative, but is/has:
o A previously healthy person <65 years of age hospitalized for ILI OR
o ILI and resides in a state without confirmed cases but has traveled to a state where there are cases (does not apply to anyone from Ohio anymore) OR
o ILI and has an epidemiologic link in the past seven days to a confirmed or probable case
To some extent, our ability to use post-exposure prophylaxis on a wide scale basis may be dictated by availability of drugs. It is certainly better to treat those who are symptomatic, and treat them quickly, than to use widespread prophylaxis for patients who might never have developed the disease. Stay tuned for updates, as they occur. Questions? Contact Hila Collins at 937-641-3000, extension 3868 or Sherman Alter, MD, at 937-641-3329 or Thomas Murphy, MD, at 937-641-5871.
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