By Steven DiJosephÃ‚Â
It was only last summer that medical experts and health officials on both sides of the Atlantic expressed concern over the emergence and spread of various strains of antibiotic-resistant tuberculosis (TB).
In the UK, the Health Protection Agency (HPA) was battling a potentially fatal strain of TB known as isoniazid-resistant TB which first appeared in north London in 2000. Since that time, some 200 cases of the disease have been reported throughout the UK, although London, with 188, is the real Ã¢â‚¬Å“hot spot.
According to the HPA, Ã¢â‚¬Å“the failure of patients to complete courses of prescribed antibioticsÃ¢â‚¬Â has facilitated the spread of isoniazid-resistant TB.
Since the treatment regimen lasts six months or more, proper treatment of at-risk groups like the homeless and intravenous drug users is quite problematic thereby increasing the likelihood that the strain will continue spreading.
Incentives and other programs that encourage and reward those who adhere to the lengthy treatment routine are being utilized. These include giving out food vouchers, social service support, and accommodation assistance.
Between 1987 and 2003, London has seen TB cases double to 2,745 thereby accounting for 45% of all cases in England and Wales. Sir William Stewart, Chairman of the HPA, states: Ã¢â‚¬Å“The bugs are cleverer than we are. They grow, multiply, and mutate more quickly than we can deal with them. Antibiotics, though still hugely important, are no longer the saviors that they were thought to be in the 1950s.Ã¢â‚¬Â
The overuse by the medical and veterinary professions has contributed to the appearance and spread of new strains of antibiotic-resistant bacteria in hospitals and beyond.
Thus, the problem has become a global one with respect to a number of bacteria in general and TB in particular. In the U.S., for example, the groups that were once at greatest risk of developing multi-drug resistant tuberculosis MDR-TB included HIV patients, prisoners, and the homeless.
Today, however, it is more likely that new cases of the resistant form of the potentially deadly disease will be brought into the country by immigrants who have traveled from areas where there is a Ã¢â‚¬Å“raging pandemicÃ¢â‚¬Â of TB.
As pointed out above, drug-resistant TB arises when ineffective drugs are prescribed or infected patients stop taking their medication too soon thereby allowing mutant strains of the TB bacteria to multiply.
Once this type of mutant strain arises it is capable of person-to-person transmission. Whereas MDR-TB had been resistant to 2 or 3 drugs in the past, todayÃ¢â‚¬â„¢s strains are resistant to 6 to 11 drugs.
A report in the June 8 issue of the Journal of the American Medical Association (JAMA) also revealed that California has the largest concentration of drug-resistant TB cases in the U.S. with 37 in 2004. California has gone from about 20% of the nations total cases in 2001 to an estimated 33% at present.
According to the JAMA report by Dr. Reuben Granich of the Centers for Disease Control and Prevention (CDC), most of CaliforniaÃ¢â‚¬â„¢s multidrug-resistant cases of TB involve people born outside of the United States.
Dr. Granich believes that the key to controlling the problem lies in caring for immigrants and enhancing TB care overseas and not in closing the borders.
Although the overall number of cases of MDR-TB has declined by 76% since outbreaks in 1993, CaliforniaÃ¢â‚¬â„¢s total number of cases has Ã¢â‚¬Å“stagnated.Ã¢â‚¬Â The California Department of Health is concerned with the problem of imported multidrug-resistant TB since immigrants are often poor, frightened, and prone to move frequently.
The 37 California cases in 2004 cost $8.72 million in direct medical costs and contact tracing when you include the 120 people who developed latent infections from them. Normal TB cases can usually be treated in 6 months with about $2,000 of standard antibiotics.
Cases of MDR-TB can take anywhere from 18 to 36 months to treat. The cost of the often toxic, second-line drugs required can be between $28,000 and $1.2 million per patient.
Newest Strain of TB Ã¢â‚¬â€œ Known as XDR-TB Ã¢â‚¬â€œ Even More Dangerous than MDR-TB
Now, the problem of drug resistance has progressed to the point of no return with the emergence of a Ã¢â‚¬Å“superÃ¢â‚¬Â strain of the disease known as Ã¢â‚¬Å“extensively drug-resistant TB or XDR-TB.
According to data from the Centers for Disease Control and Prevention (CDC), doctors this new form of tuberculosis presents a very serious problem because it is virtually untreatable with existing antibiotics. This has left health officials with few treatment options short of radical pre-antibiotic approaches such surgical removal of diseased parts of a patientÃ¢â‚¬â„¢s lung.
In the meantime, MDR-TB has been identified in countries all over the world and is making it difficult for public-health officials to help control the spread of those strains. The CDC revealed that MDR-TB is currently infecting more people in the United States after being on the decline for more than a decade.
To be sure, TB in any form is a problem since it occurs quite extensively in places that are least able to treat it effectively. Thus, even treatable TB strains are going untreated or inadequately treated.
The disease is caused by a bacillus that is spread through the air. Coughing is the usual method of transmission. Some 9 million people worldwide are diagnosed with new cases of TB each year and the disease claims 2 million lives annually.
The CDC and the World Health Organization (WHO) surveyed 25 tuberculosis laboratories on six continents and discovered that 2% of TB samples from patients tested between 2000 and 2004 were resistant to the two most commonly used TB drugs as well as other secondary treatments. That would be MDR-TB.
The real concern, however, is the emergence of XDR-TB since that strain would make even advanced countries, with the latest antibiotics, vulnerable to epidemics. In short, XDR-TB could make it virtually impossible to control TB on a global scale.
The agencies have defined XDR TB as those cases in which isolates were resistant to isoniazid and rifampin and at least three of the six main classes of second-line drugs (aminoglycosides, polypeptides, fluoroquinolones, thioamides, cycloserine, and para aminosalicylic acid).
Drug-resistant TB can occur when patients do not finish a particular treatment or when doctors prescribe ineffective drugs.Ã‚Â Both of these scenarios can cause mutant strains of the TB bacteria to multiply.
According to the WHO, there are almost 400,000 new cases world-wide of drug-resistant TB each year.Ã‚Â The CDC says that there are six new TB drugs that will soon be tested in humans.Ã‚Â These drugs could potentially help treat cases of MDR-TB and XDR-TB.
The majority of cases of XDR-TB have been reported in South Korea, Eastern Europe, and Central Asia but there have also been a number of cases in the United States.
Officials are concerned about this new ultra-resistant form of TB because it is already difficult to treat typical cases of TB.Ã‚Â TB is also extremely common amongst individuals with HIV and AIDS.Ã‚Â In fact, one-third of the 40 million men and women with HIV also contract some form of TB.Ã‚Â TB can also speed the progression of HIV to AIDS.
In 2004, the number of people in the U.S. with MDR-TB increased 13.3%. Ã‚Â As stated above, the majority of people in the U.S. with MDR-TB or XDR-TB are foreign-born.Ã‚Â About 128 people were diagnosed with MDR-TB in 2004, 97 of whom were from countries such as Mexico, the Philippines, and Vietnam.