A question for medical types about TB

Factual Questions
1

My brother was recently found to be infected with TB. (He’s in the Army and they figure he picked it up in Bosnia a few years ago.) For some reason it wasn’t detected when he returned and we spent a few days with him last Christmas and at another visit.

He was told by the doctor that discovered the infection that he wasn’t contagious at the time and they aren’t planning to treat it at all for several months.

We had ourselves and our young children tested (negative) and my parents, who are both in poor health, are going to be tested, too.

However, my brother is leaving for Korea in 3 months and there are plans for him to take an extended trip with my parents and to visit with us before he leaves.

My question is, how safe is this? My husband wants to keep the kids away from him and require that my parents be tested again after they’ve been with my brother. Is this necessary?

2

Is he symptomatic, or did he just have a positive TB test?

Dr. J

3

As far as I know he just had a postive test.

He’s 38 and more or less healthy, although he did smoke for quite a while.

4

If you don’t develop active disease (night sweats, fever, coughing, coughing up blood in the most extreme cases) then you are not very contagious. Your body does a pretty good job at walling up the infection. With infection, you stand a certain chance (I think it was 2.5%/year if you are healthy) of developing active TB, but it may not ever happen. I convert a PPD, as do many of my classmates. They just X ray my lungs now instead of giving me a PPD skin test.

5

My brother was that way as a child, too. (He was allergic to practically everything.) They did do an X-ray this time and there is a patch on his lung. Does this affect likelihood of being contagious?

6

Say, I think I remember about two months ago(when I got my PPD by Mantoux, more on that later) my pediatrician told me that if the person with positive PPD is older than 35(?) years old, sometimes it was not treated(or it was more risky). Reason? The drugs currently used to treat TB damage the liver. If you are young, the damage is reversed over time, but the older you are, the more chances liver complications may develop.

Since he was a pediatrician, all the kids he sees which have positives PPD’s AND xrays(and double checked positive PPD’s) are treated against TB, just to get over it soon and early.

On the PPD by Mantoux:

I hate that test. With the older, just 4 pinches, I never got a bump. Zip, zero, nothing, not a mark. When I had my PPD by Mantoux, I developed a rash. Fortunately, according to my doctors, since it was only rash and no bumps, they said it was positive. I had X-rays just to be sure, and sure enough, the x-rays were negative. My parents and I later assumed that since I am allergic to insects bites and other such(wich are/have proteins), then probably it was an allergic reaction to the protein the Mantoux test has.

7

"When I had my PPD by Mantoux, I developed a rash. Fortunately, according to my doctors, since it was only rash and no bumps, they said it was positive. I had X-rays just to be sure, and sure enough, the x-rays were negative. My parents and I later assumed that since I am allergic to insects bites and other such(wich are/have proteins), then probably it was an allergic reaction to the protein the Mantoux test has.

The way you read a Mantoux test is by measuring the area of induration (firmness). Redness doesn’t count. If you develop induration more than a certain diameter (usually 10 mm), the test if “positive.” A positive just means that you have been infected but doesn’t mean that you are either diseased or infectious. A negative chest x-ray doesn’t mean you aren’t infected but does strongly suggest that you do not have and never had serious TB going on in one of your lungs (and therefore are not going to give anyone TB by breathing on them). (You could, of course, have TB elsewhere in your body and that is why the doctor takes a history (asks you a lot of questions) and examines you in addition to getting the chest X-ray.)

The tine test (“just 4 pinches”)is considered obsolete. It just isn’t accurate enough.

8

Infectious disease specialists (I am not one)make a distinction between TB “infection” and TB “disease.” Infection is defined as having a positive skin test to an intradermal injection of “tuberculin,” or “purified protein derivative [PPD].” This detects whether or not you have a cell-mediated antigenic response to PPD. A postive response indicates a prior “exposure” to Mycobacterium tuberculosis [MTB], the bacterium that causes TB. It is important to realize that people with deficits in cell-mediated immunity (i.e. those with AIDS, transplant recipents, etc.)may be infected with MTB and not have a positive PPD skin test.

TB “disease” involves having symptoms of TB (cough, fevers/chills/night sweats, weight loss, and symptoms of pneumonia). Most important, from the public health standpoint, TB disease implies that MTB is active and contagious. Contagious TB is spread by droplet infection, and contagious patients will shed infectious MTB in their sputum. This may be tested by culturing sputum from suspected patients.

The current recommendations for treating asymptomatic TB infection is to treat for about 6 months with a “prophylactic” regimen of INH. The aim of this is to reduce the risk of developing TB disease at a later date.

For those with TB disease, treatment is with at leats two or three antibiotics, usually INH, rifampin, and something else (PZA, ethambutol, streptomycin, etc.). Such treatment is guided by the results of TB cultures tested for antibiotic sensitivity/resistance.

ALL of the anti-tubercular drugs are potentially hepatotoxic, so treatment must be closely monitored.

In the USA, TB was becoming “extinct” until the late 1980’s. There has been a resurgence of TB in the US, which may be blamed upon various things, such as homelessness and AIDS. However, the main culprit is probably immigration to the US of immigrants from areas where TB is endemic, namely ASIA (especially Southeast Asia and the Indian subcontinent), Mexico and Central America, and Eastern Europe.

9

[[In the USA, TB was becoming “extinct” until the late 1980’s. There has been a resurgence of TB in the US, which may be blamed upon various things, such as homelessness and AIDS. However, the main culprit is probably immigration to the US of immigrants from areas where TB is endemic, namely ASIA (especially Southeast Asia and the Indian subcontinent), Mexico and Central America, and Eastern Europe.]]

AIDS is indeed in large part responsible for a resurgence of active TB in many part of the world, including the east coast of the US.

Most positive PPD skin tests just show exposure to TB, not active disease. Those of us who work for the health dept. are required to test for it, and if we test positive, to get chest xrays and treatment. Most who test positive have spent time in third world countries, but are not sick with the disease.

10

An update from the CDC’s “Summary of Notifiable Diseases, United States, 1999” found at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4853a1.htm

In 1999, a total of 17,531 tuberculosis (TB) cases (rate: 6.4 cases/100,000 population) was reported to CDC from all states and the District of Columbia. This is a 5% decrease from 1998 and a 34% decrease from 1992, when cases peaked during the resurgence of TB in the United States. During 1992–1999, TB cases among U.S.-born persons decreased 49%, whereas cases among foreign-born persons increased 4%. Since 1993, when states began reporting initial drug susceptibility results to CDC, the number of multidrug-resistant TB (MDR TB) cases among persons with no history of TB decreased from >400 (2.5%) to <150 (1.1%).

These declines appear to be the result of successful efforts to strengthen TB control after the resurgence of TB and the emergence of MDR TB. The relatively stable number of cases reported among foreign-born persons supports the inference that most cases are caused by infection with Mycobacterium tuberculosis in the person’s country of origin. CDC has collaborated with state and local health departments to publish recommendations for enhancing TB control efforts among foreign-born persons and is working with these jurisdictions to expand current efforts based on these recommendations (MMWR 1998;47[No. RR-16]).

11

Yeah that was what my doctors said. They marked “negative” on the health sheet, but ordered me to take the x-ray. Still, walking around with a 10mm of diameter rash in my arm…some people might see it and think I had a positive PPD. Apparently, my doctors told me, some people DO take rash as a sign of positive PPD. Misinformation, probably.