24 April 2009

Friday

Novel Influenza Virus A (H1N1) with Genes of Swine, Avian, and Human origin causi= ng infection in parts of California, Texas, and Mexico, with some person-to-p= erson spread

In a rapidly evolving situation as of this evening (Frid= ay, 24 April) information from the US CDC, the WHO, the Minister of Health of Mexico, and other sources can be highlighted as followed:=

I. The US CDC has laboratory confirmation of eight (8) non-fatal human infections with a novel influenza virus, with 6 in southern California (San Diego County and Imperial County) and two (2) near San Antonio, Texas. The identification o= f more cases is anticipated in the USA.

II. The CD= C media conference call yesterday, Thursday, 23 April at 3pm included data from Dr. Nancy Cox, Chief influenza virologist at the CDC, that this novel virus has genetic components from th= ree different species: swine, avian and human. The written transcript of this teleconference yesterday quotes Dr.Cox as follows: <= /p>

“So we have some gene segments that are North American swine influenza viruses. Some gene segments North American avian influenza viruses. One gene segment from a human influenza virus and = two gene segments that are normally found from swine influenza viruses in Asia = and in Europe.”

In the CDC’s MMWR Dispatch from April 21 reporting the initial two cases from the US= A infected with this novel virus, it was stated that the neuraminidase and ma= trix genes are of swine influenza origin, but from viruses in swine in Europe/As= ia and not North America. Which of the gene segments is of human origin was not stated in yesterday’s conference. Nor was the origin stated of the haemagglutinin gene, the influenza gene responsible for the dominant immune response against an influenza virus.

III. = ; There is at least limited person-to-person spread according to the CDC, citing the father and daughter infected in California, and possibly the= two teenagers near San Diego who attend the same school. Dr. Cox of the CDC stated yesterday in the same teleconference:

“So, we're seeing basically a virus that appears to be spreading from pe= rson to person in humans and viruses have very similar genetic characteristics to each other”.

IV. The CDC has provided (Ap= ril 20) interim guidance for clin= ical evaluation of persons with suspected swine flu on their website titled: Int= erim Guidance on Infection Control and Antiviral Recommendations for Patients wi= th Confirmed or Suspected Swine Influenza A Virus Infection www.cdc.gov/flu/s= wine/recommendations.htm

V. CDC also advised: Clinicians should consider the possibility of swine influenza virus infections in patients presenting with febrile respiratory illness who:

1.&n= bsp; Live in San Diego County or Imperial County, California or San Antonio, Texas or

2.&n= bsp; Have traveled to= San Diego and/or Imperial Coun= ty, California or San Antonio, Texas or

3.&n= bsp; Have been in con= tact with ill persons from these areas in the 7 days prior to their illness onse= t.

If swine flu is suspected, clinicians should obtain a respiratory swab for swine influenza testing and place it in a refrigerator (not a freezer). Once collected, the clinician should contact their state or local health department to facilita= te transport and timely diagnosis at a state public health laboratory.

VI. Today the CDC published on their website (www.cdc.gov) another Morbidity and Mortality Weekly Report (MMWR) “Dispatch” that gives more detailed clinical and epidemiological information on the US pati= ents with this “swine flu” virus infection.

VII. Today, the CDC held another media teleconference starting at 2:30pm. The acting Directo= r of the CDC, Dr. Richard Besser, participated.&nbs= p; It was reported that of the initial 14 samples tested at CDC-Atlanta from patients in Mex= ico with an influenza-like illness, seven (7) were positive for this swine flu virus. No clinical details were reported on these seven patients from Mexico. However, it was reported in this conference that the Minister of Health of Mexico had stated that at least some deaths were due to swine flu. (= In the USA<= /st1:country-region> none of the 8 lab-confirmed patients have died. Only one, who was immunocompromised, required hospitalization).

VII. Early today the World Health organization (WHO) held a conference in Geneva regarding = this situation. It was reported that the WHO had activated their emergency respo= nse command center. Later today the WHO posted on their website a summary updat= e. Regarding Mexico they reported the following:

“The Government of Mexico has reported three separate events. In the Federal District of Mexico, surveillance began picking up cases of ILI starting 18 March. The numbe= r of cases has risen steadily through April and as of 23 April there are now more than 854 cases of pneumonia from the capital. Of those, 59 have died. In San Luis Potosi, in central Mexico, 24 cases of ILI, with three deaths, have been reported. And from Mexic= ali, near the border with the United States, four cases of ILI, with no deaths, have been reported.

Of the Mexican cases, 18 have been laboratory confirmed in Canada as Swine Influenza A/H1N1, while 12= of those are genetically identical to the Swine Influenza A/H1N1 viruses from = California.=

The majority of these cases have occurred in otherwise healthy young adults. Influenza normally affects the very young and the very old, but these age groups have not been heavily affected in Mexico.

Because there are human cases associated with an animal influenza virus, and becaus= e of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern”.<= /o:p>

Certainly a number of critical questions remain, and some answers are likely to appear this weekend and over the coming days and week(s). A central issue is wheth= er there is sustained and efficient human transmission of this novel influenza virus. If so, then the WHO wo= uld likely consider whether or not to raise their pandemic alert level and what that would mean if a large urban area is already involved with the outbreak= in terms of potential interventions.

The WHO, Pan American Health Organization (PAHO), the US CDC, and the governmen= ts of Mexico and the USA are involved, among others. One can anticipate evolving interim guidance update= s as more data becomes available day-by-day.

Daniel R. Lucey MD, MPH<= /span>

EROne Institutes, Department of Emergency Medicine

Washington Hospital Center

Adjunct Professor of Microbiology and Immunology

Georgetown University Medical Cente= r, Washington, DC

Website for this posting: www.BePast.org (re= quires Internet Explorer)

DRL23@georgetown.edu