Skipping meds yields drug-resistant strain
By Eric Fleischauer
Any Wayne Farms employees who begin preventive therapy for tuberculosis but don’t complete it are at a greater risk of developing drug-resistant forms of the infection.
“The No. 1, 2, 3, 4 and 5 top reasons for drug resistance is medical noncompliance,” said Dr. Scott Harris, an infectious disease specialist who works in the TB clinic at the Morgan County Health Department.
Forty-seven employees of the Wayne Farms chicken processing plant tested positive for TB out of 167 who received skin tests Oct. 11. One employee and one former employee have active TB disease, which is contagious.
Most forms of TB are curable, but drug-resistant forms are a challenge to the health profession. In May, a Georgia lawyer with multidrug-resistant TB made headlines when he allegedly ignored medical instructions and left the country for his honeymoon.
By far the most serious consequence of failure to take the complete regimen of TB medication occurs when the patient has active TB. Only active TB is contagious.
By taking some medication, but not enough to kill the TB bacteria, a patient increases the likelihood that the TB will develop the ability to resist the medication that was used.
Multidrug-resistant TB is “a smoldering fire that could ignite an inexorable TB pandemic,” said Dr. Michael Fleenor. He is health officer of the Jefferson County Department of Health and chairman of the Centers for Disease Control Advisory Council for the Elimination of Tuberculosis.
Fortunately it also is unusual.
Low rate in state
“Alabama has an extremely low rate of drug resistance,” said Pam Barrett, field services coordinator of the state’s Tuberculosis Control Division. “In the past two years, we’ve only had two cases that were multidrug resistant, and (the patients) were U.S. born and related to each other. Both of them have been cured and do not pose a threat to anyone.”
To guard against the risk of spawning multidrug-resistant TB, Harris said, patients with active TB — including the two who worked at Wayne Farms — must take their four-drug therapy while being observed by a health worker. Because the treatment regimen lasts for six to nine months, that can be difficult.
“Either they come to the Health Department (two or three days a week) or the nurse goes to their home,” Harris said.
If they have a home.
“We have a lot of TB cases where people are not in the best economic situation,” Harris explained. “The nurses go to the soup kitchen or go to the overpass — wherever they have to go to find them. The nurses are really remarkable.”
Only one of the 47 Wayne Farms employees who tested positive has active TB, but doctors encouraged all of them to take a TB medication called isoniazid, usually referred to as INH. For the other 46, the purpose of the INH is to prevent latent TB from progressing to active TB disease.
If they start, but fail to complete the regimen, they stand a greater chance of developing a form of TB that is resistant to INH. That does not matter if their TB remains latent, Harris said, but if it progresses to active TB disease it causes problems. People who are infected by them may not be curable by INH.
“If the person that shared their germ with you is resistant to a drug, then you will likely be resistant to the same drug,” said Barrett.
Most never develop
Ninety percent of those infected with TB never develop active TB. Once they have it, though, unless treated, they have it for life.
“The best way to describe it in non-medical terms is that once you breathe in those TB germs and become infected, your immune system puts those germs to sleep,” said Barrett. “In cases where a person’s immune system does not keep the germ asleep, it wakes up and starts multiplying and eating the lung.”
Completing therapy puts the TB bacteria “permanently asleep,” Barrett said, so it cannot become active even if the immune system later is compromised.
Less effective drugs
A few other drugs are available to fight TB, but generally they are less effective or have more side effects than INH.
“Sometimes you’ll have people who are transient or just not compliant,” Harris said. “They’re supposed to come to the health department once a month to pick up their next month’s supply. It’s offered to the patient, but we can’t compel (those with latent TB) to take it.”
TB, said Harris, is not as infectious as some people think. The likelihood of infection is up to 50 percent for those who have a “close contact” with TB disease.
“A ‘close contact’ is typically defined as someone within three feet for more than 15 minutes of time,” Harris said.
Once infected by a person with active TB, additional exposure does not increase the risk of the infected person progressing from latent to active TB.
“Further exposure or longer exposure won’t affect what happens to you,” Harris said.
Only active TB is contagious, and active TB almost always has noticeable symptoms.
“It’s exceedingly unusual for somebody to be infectious who is not clinically ill,” Harris said. “You can see that they are ill.”
People with compromised immune systems — from diabetes, HIV, malnutrition or other reasons — are more likely to develop active TB, Harris said. The high rate of TB disease in developing countries is mainly a result of malnutrition.
In other cases, Harris said, doctors do not know why one infected person will develop active TB disease, while another will have a latent infection without symptoms.
Both of the Wayne Farms workers with active TB disease are Hispanic. While foreign-born Hispanics are more likely to be infected with TB than people born in the United States, Harris said the odds are still low.
In 2006, 196 cases of active TB were reported in Alabama. Only 39 were Hispanic.
“It’s a small number of cases overall that are Hispanic people,” Harris said. “They are disproportionately infected only if they come from the developing world. Most patients with TB are not illegal immigrants.”
One of the major complications in dealing with TB in a workplace, like Wayne Farms, that has many people born outside the U.S. involves immunizations.
Vaccine affects test
The United States does not recommend using a TB vaccine because it is not particularly effective. Many countries, including Mexico, do use a vaccine.
“It prevents TB in a fair number of kids, but what it also does is it gives you a positive skin test forever,” Harris said.
At least some of the Wayne Farms employees, who tested positive for TB probably did so because they had received the vaccine as children, not because they were infected, Harris said.
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