CDC: HIV rates down, but new cases steady. What gives?

by James Hubbard, M.D., M.P.H.

The CDC reports HIV transmission is down.  Great news.  I found out when I read an interesting post on a Chicago Tribune blog.  I suggest you read it, also.  But wait a minute. A few days ago, I posted that the rate of new HIV cases has been steady for the past few years.  Not great.  What gives?

See if you can follow me on this.

Here goes.  The following are round figures and rough estimates. “Transmission rate” refers to the percentage of HIV-positive people who transmit the disease.

There are about 1.1 million HIV-positive people living in the U.S. and over 56,000 new cases yearly.  That means there’s a 5-percent (56,000/1.1 million x 100) transmission rate.  Back in the 1980s the transmission rate was as high as 44 percent.

Since most HIV patients are living normal lifespans, the amount of people with HIV will rise each year.  Yes, some die (17,000 in 2006) but next year, there will be about 1.15 million alive. If the transmission rate remains the same, there will be actually more new cases (1,150,000 x .05 = 57,500).  If new cases are to remain the same (the bad news recently reported) the transmission rate must go lower every year (good news).

During current times, when there is decent treatment but no cure or vaccine, this will continue to be the case.

Remember this when other reports come out, such as the recent news that worldwide lung cancer will double in 10 years.  Three reasons are:

  1. Smokers will continue to get cancer at the same rate.
  2. People in third-world countries continue to smoke more.
  3. Population will continue to increase dramatically in these countries.

So the HIV news is mixed but promising.  It shows that education and prevention are working but can get better.  Remember, the transmission rate is how many people with HIV give it to others.  Since HIV is not transmitted with every HIV sexual or needle encounter, the encounters must be many times that.

There is definite room for improvement.


Graph source: Holtgrave D, Hall HI, Rhodes P, et al. Updated Annual HIV Transmission Rates in the United States, 1977-2006. JAIDS. Advance
Note from CDC: The large fluctuations in the graph prior to 1980 are due to the relatively small numbers of persons living with HIV at that time and the limited surveillance structures that were in place.

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2 Responses to “CDC: HIV rates down, but new cases steady. What gives?”

  1. Dr. J Says:

    I wish everyone would encourage appropriate preventive measures for transmitted sexual diseases!

    Dr. Js last blog post..Dr. J on doctors and angry patients

  2. James Hubbard, M.D., M.P.H. Says:

    Dr. J,
    I agree.

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