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Old January 15, 1999, 07:38 PM   #33
olazul
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Dennis,
I am happy to say that I am in no way connected to the CDC. I am in fact a simple "foot soldier" hoping to clarify an area where I have something to give.

Let me also say that I never want to be in the position of defending a government agency.

Now lets talk about HIV testing and the blood supply. Most stats are based on a population of 271 million in the U.S..

TESTING- Before being diagnosed with HIV you must have a positive EIA test(which tests for your antibodies to the disease) and a positive western blot. The accuracy of these tests combined is greater than 99%. There is a window where current tests cannot detect the virus. This is because sufficient antibodies do not yet exist. This window is generally 3mos. but can be up to 6. In certain very rare cases this window can last 2yrs or more.
If you are HIV+ and develop certain clinical conditions you are diagnosed with AIDS.

BLOOD SUPPLY- The blood supply is currently tested for HIV1, HIV2, HTLV-1, HepB, HepC, and Syphilllis. There is a window with HIV where the person is infected, and also infectious, where someone could give blood and not have it detected by the screening tests(see above). They do attempt to weed these cases out by denying people who even have risk factors for HIV. At the end of 1992 there were 4,959 cases of transmission by recieving blood/tissue products. All but 21 of those occured before screening started in 1985. To give you an idea of safety, there are around 17 million units of blood products used every year. Studies have shown blood product trasmission rates of HIV between 1/38,000 and 1/300,000. There was a study in 1990 by the CDC and American Red Cross that showed a rate of 1/225,000.

As to other infectious diseases and CPR. Some facts may have been posted already. Those diseases listed are the ones you should be most worried about.

HIV- Roughly .4% of the population in the U.S. is HIV+(.13% is documented HIV+). There have been no reported cases of transmission via CPR. There has only been one case of transmission via french kissing- I think this is believed to be a blood exposure in reality. There is a 1/250(4%) chance of contracting it through a needlestick. There have only been 54 documented and 133 possible cases of transmission of HIV to a U.S. healthcare worker since the inception of testing the disease(84-85?).

TB- I do not know if this has ever been spread by CPR. 10-15 million people are infected in the U.S.(vast majority is pulmonary). On average, only 10% will ever have the active/contagious form of the disease in their lifetime. If the disese is not active, it is not contagious. I have not seen numbers about the # of active cases currently in U.S, but this would be much less than 1-1.5 million( .4-.6% of population) because it would be spread over their lifetime. To spread pulmonary TB one must cough deeply and aerosalize the germ. I do not know if CPR mimics this cough, I doubt it does- really efficiently anyway(it is very difficult sometimes to get a good sputum from patients, even when they try hard). "Really contagious" is relative. If someone had active TB and I was in an ambulance I would treat it as such. But, in the realm of infectius disease, it generally takes a prolonged encounter- like living with someone. The odds of catching the disease from someone with ACTIVE TB, in this circumstance, is 23%. Of course just like the girl at the prom, you might get "lucky" the first time. Plus if you sum up the time you spend with these people as an EMT over 20 years it adds up to a prolonged exposure. The vast majority of TB is treatable with medication. There is a small percentage of drug resistant strains which is on the rise(did not look up the #, but again only 10% of these will ever have active disease)

Hep B- Occurance of less than 2% in population with ~1 million chronic carriers(.4% of pop). You can get this by a person with an acute infection or chronic infection. 6-10% go on to chronic infection, .5-2% go on to liver failure. Transmission has not been documented by kissing although it is present in saliva(you generally get this by sharing needles or sex). There are some cases of infection by bites. I do not know if any cases have been transmitted by CPR. You can get vaccinated against this disease. If you are an LEO, medical personel, still dating, or other dealing with the public in an intimate manner- vaccination is HIGHLY recommended. Make sure you get tested for seroconversion("immunity") after the series. You may have to have another round of shots.

HepC- I screwed up here before, I misread the stats. This is more common than I previously thought, with a prevalence of 1.8%(majority are carriers) in our society. If you get a needlestick there is a 5-10% chance of getting it. Routes of transmission are not well understood at this time other than it is definitely spread by blood contact. It is very bad though as most cases(70%) go on to liver failure and ~85%(or more) will develop carrier status. Treatment is available and is effective 15-30% of the time. No vaccine is available. Good news is that in recent years the incidence of new cases is down 75% due to screening the blood supply.

There are a myriad of other diseases including meningitis which can ruin your day. I would caution against dwelling on diseases too much. There is a saying that 2nd year medical students are all hypochondriacs, as they have learned alot of what can go wrong but have no clinical framework to put it in perspective. One can go mad thinking about germs.

To summarize the encouraging news:

HIV- no known cases of transmission by CPR.
Only 1 case of transmission by kissing.

TB- usually takes a prolonged encounter and really good coughing. BTW don't inhale the patients breath while giving mouth to mouth, turn face away etc.... Majority of cases treatable.

HepB- get vaccinated. No known transmission by kissing. Only .5-2% of infected go on to have liver failure.

HepC- This is bad. lets do the math though. Assume transmission rate of 5%(very high as this is low end for a needlestick). What are the odds that you will perform CPR in general public on a HepC+ person AND that you will contract this disease? .018 X .05 X 100%= .09% = 1/1,000 (we can probably add at least another zero or two here for mouth to mouth which would make it 1/10,000-1/100,000).

Again we are talking about one exposure of mouth to mouth with a person who is not blatently disgusting health/bloody wise. I would caution against placing your mouth on blood- this will increase your risk significantly. While I cannot give you one number, I think you can see that to get a bad disease from this type of exposure would be rare(my opinion, do with the information as you will). There are risks, minimize them when you can.

BTW- I have several messages out to the CDC and elsewhere as to whether there have been reported cases of hepatitis or TB (now HepC also)through giving CPR. Don't hold your breath. If I get it, so will you. Dennis, I will also attempt to get the # of healthcare workers who contract potentially terminal bugs/year.
Also- my #'s and information were derived from a large number of references, some up to 3-5 yrs old. They are very good approximations. I am not publishing, so I have not included the numerous citations. If anyone has a question about a particular fact or # I will tell you where I got it.

I really appologize for the length of the post. You won't have to suffer another long one from me for awhile - promise.

Olazul

This post was revised due to faulty information on Hep C(a little crow, on occaision, is good for the soul) and addition of a couple of clarifying stats elsewhere. No other changes in numbers were made.

[This message has been edited by olazul (edited 01-16-99).]
 
 
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