Each disease makes the other one worse
The World Health Organization (WHO) in Geneva has collected these statistics about the impact of TB on HIV and vice versa, drawing the conclusion that each epidemic has a worse impact on populations in developing nations because of the existence of the other one. Here are some of the facts about the TB and HIV epidemics and coinfection:
• About 70% of the people living with HIV are in sub-Saharan Africa, and of the 24 countries with an HIV seroprevalence rate above 5%, all except Haiti, are in sub-Saharan Africa.
• One-third of the HIV-infected population also are infected with Mycobacterium tuberculosis. HIV is the most powerful source of reactivation of latent TB infection to active disease, and people with HIV who become newly infected with TB rapidly progress to active TB.
• TB, accounting for 15% of AIDS deaths worldwide, is the single biggest killer of HIV-infected people, and since the HIV epidemic took hold on sub-Saharan Africa, the TB case fatality rates have increased from less than 5% to more than 20% in the countries most impacted by the HIV epidemic.
• More than two-thirds of people with sputum smear-positive pulmonary TB also are HIV-positive; and research suggests that an HIV-positive person who is coinfected with TB will have an enhanced HIV replication and possibly an accelerated progress to AIDS.
• Despite the potential of TB treatment costing as little as $10-$20 per person, diagnosis and treatment are not readily available to people living in developing nations.
• In the Americas, high TB smear-positive notification rates are reported in Bolivia, Brazil, Haiti, Honduras, and Peru; in Europe, many of the nations with the highest number of estimated TB cases are in Eastern Europe, which now is experiencing new outbreaks after 40 years of steady decline. The Russian Federation, for instance, had an estimated 192,538 TB cases in 2000, followed by the Ukraine with an estimated 39,069 cases, Romania with 30,260 cases, and Uzbekistan with 25,993 cases. Other European nations with high estimated numbers of TB cases are Turkey, Kazakhstan, Poland, Spain, Germany, and Tajikistan.
• While there are a quarter of a million new TB cases each year in Eastern Europe, there are nearly 3 million new TB cases per year in Southeast Asia.
• More than half of the TB smear-positive cases reported under direct observational therapy strategy (DOTS) in 2000 were found in India, the Philippines, Ethiopia, South Africa, and Myanmar. India with 28% of these cases and the Philippines with 19% were the only nations with more than 6%.
• In areas with low HIV prevalence, the TB incidence rate could decline at 5%-10% a year if case detection and cure rates exceed 70% and 85% respectively, according to mathematical modeling. The incidence rate would be halved in 10 years at a decline of 7% per year.1
• Every country surveyed has reported incidences of drug-resistant TB, and multidrug-resistant TB, which is disease due to TB bacilli resistant to at least isoniazid and rifampicin, is rising at alarming rates in the former Soviet Union and some other countries.
• Drug-resistant TB can cost 100 times more to treat than drug-susceptible TB.
Reference
1. Dye C, Watt CJ, Bleed D. Low access to highly effective therapy: A challenge for international tuberculosis control. Bull World Health Organ 2002; 80(6):437-444.
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