HIV and TB: a bad mix

The CDC has a report on HIV and TB, and the bad news is that if you had a TB infection and then get HIV, your chance of coming down with TB is ten times higher than if they didn’t have HIV, so the CDC is asking that everyone who gets a TB diagnosis get checked for HIV:

In the United States, after TB exposure and infection, HIV-infected persons who do not receive appropriate treatment progress to TB disease over 5 years at a rate 10 times greater than that for persons not infected with HIV (2,3). In 1989, CDC recommended that all TB patients be offered HIV testing (4) and, in 2006, called for routine HIV screening of all TB patients after the patient is notified that testing will be performed, unless the patient declines (opt-out screening)

Here’s the background.
Most people exposed to the TB germ don’t “get” tuberculosis. Their own body’s immune system fights it off.

A small percentage of people (usually children) exposed to TB will develop generalized “primary” infection (which is another story) but most people’s immune system fights the infection off, leaving no sign of tb, or sometimes you will develop a mild case in the upper lung– a tubercule– which the body walls off and you get better. This is called a “latent” infection.

The problem is that the “walled off” germs can get lose if your immune system weakens because you get old, diabetic, malnourished, sick, or any of the other reasons that cause a weak immune system.

That is why TB is a disease of poverty more than infection: Yes, middle class people did die of TB, but it was most rampant among the poor who lived together in crowded poorly ventilated houses.

But in healthy people, the immune system fights off the disease, so unless you worked in the slums, the Indian reservations, or among the coal miners, before HIV epidemic started you probably never saw a case.

Fifty years ago, they still screened for TB with yearly Chest X Rays. But with an increase in good nutrition, TB became rare, and with Streptomycin and other drugs, the TB sanitariums shut down. And young people no longer were exposed to TB as in the past.

So when we screen nowadays for tuberculosis, we do a skin test. If the skin shows an immune reaction to TB antigens, we know they have been infected with tuberculosis.

The next question is what to do about it.

The chance of a person with a positive skin test coming down with TB is low (if I remember correctly, it’s about 1 percent per year). If you treat that person with anti tuberculosis medicine (usually INH) their chance of getting TB is no higher than if they never had been exposed to TB. Essentially it kills any live germs hibernating in the body that might break out later and cause problems.

For awhile, they treated with anti Tuberculosis drugs for positive tests. Then they found the drug INH could cause hepatitis, and the rate of hepatitis for people over age 30 was higher than the chances of coming down with TB. So then they only treated people under age 30 or who had positive X rays.

Then they found you didn’t need to give the medicine for a year (I took it for a year, but twenty years later when my son tested positive, he only had to take it for six months).

But then the old TB cases started to age.

And with age, and especially with Diabetes, we ran into the question of treatment for those who never received the antibiotics when young. LINK

Diabetics have 4 times the rate of coming down with TB; coalminers with silicosis 30 times the rate, and those on hemodialysis 10 to 25 times the rate of normal people getting the disease.

This might not be a problem in suburbia, but the Indian Health Service became very worried about reactivated tuberculosis in their diabetic patients. It also became a worry for our patients receiving immune altering drugs for cancer or rheumatoid arthritis, or on dialysis.

But another problem is tuberculosis in HIV positive patients.

Now, some groups of HIV positive people are not at very high risk for TB, but others are.

And the latest CDC surveys showed the main problem was in Black HIV positive patients. Like American Indians or coalminers, they might have had their TB exposure as a child, but not picked up or treated.

The highest rates are with Drug abusers, especially IV drug abusers, the homeless, non Hispanic blacks, alcoholics, and those in prison.

HIV testing has so far been voluntary, but now the CDC is going to push for all TB patients to get checked for HIV, since you need to treat both diseases to get a cure.

The worst part of all of this is that the homeless, and intercity blacks, are more likely to “fall through” the cracks of a disjointed health care system.

American Indians on reservations are monitored by the Indian Health service, and often Urban Indian clinics. Coalminers with silicosis, patients on dialysis, patients post transplant are also on “lists”, but IV drug abusers of our inner cities often disappear, and the clinics are often large and impersonal. The mistrust of the medical establisment is also a major problem among inner city blacks, partly due to the memory of the Tuskegee experiment, (where black men with syphillis were let untreated) and partly due to racism or perceived racism. (Many clinics are staffed by overseas trained doctors, whose demeanor is often interpreted as racism, and of course there is racism alas in both US and immigrant doctors who misunderstand the cultural differences.)

Some clinics are indeed doing outreaches in the inner city, often via the black churches, but there is a worry that these cases might be missed and spread Tuberculosis into the general population in subways and other closed areas.

The crackdown on undocumented aliens, who also have a higher rate of Tuberculosis, is also a worry for public health, since the immigrants might be less likely to seek medical care for fear of being deported. However, that is another topic for another day.


Nancy Reyes is a retired physician living in the rural Philippines. Her webpage is Finest Kind Clinic and Fishmarket and she writes medical essays on HeyDoc Xanga Blog

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