AIDS Alert International: Dual infections with HIV and M. tuberculosis complicate prevention and treatment initiatives in Africa
Problem is growing in other parts of world
More than 34 million people worldwide are infected with HIV, and about one-third of them are co-infected with Mycobacterium tuberculosis. The dual infection has created a deadly and expensive dual epidemic, particularly in sub-Saharan Africa, where more than 24 million HIV-infected people reside.
International health organizations estimate that only 20% to 25% of all TB patients worldwide have access to effective diagnosis and treatment provided under the directly observed therapy, short-course strategy (DOTS), which is acknowledged to be the best TB control method.
In many countries in sub-Saharan Africa, up to 70% of patients with sputum smear-positive pulmonary TB are HIV-positive, and half of people with HIV develop TB. While precise statistics are not available, most international health officials would agree that TB is the single leading cause of death among HIV-infected Africans.
HIV infection has made TB infection even more deadly by promoting rapid development of TB disease in people who are newly infected with TB or whose TB infection has been dormant, says Dermot Maher, BM, BCh, a medical officer with the Communicable Diseases Control, Prevention, and Eradication of the World Health Organization (WHO) in Geneva.
Likewise, studies show that a person’s immune response to M. tuberculosis infection enhances HIV replication and may accelerate the progression of HIV disease. Together, the two epidemics have wreaked misery and death throughout sub-Saharan Africa.
While WHO and other international organizations have been focusing on Africa — the region of the world in which the problem is the most critical — they’ve kept an eye on other potential hot spots. Cambodia and northern Thailand both have high HIV infection rates coupled with high TB infection rates, Maher says. "In those parts of India where HIV is more common, [there’s a] risk of fueling the TB epidemic," he adds. "But in India, overall HIV infection rates still are relatively low."
But the dual TB/HIV epidemics in those Asian nations are dwarfed in comparison to sub-Saharan Africa’s troubles.
"We’ve had the chance to observe over the past decade — and very many sub-Saharan African countries have seen — terrific escalations of TB due to HIV and poverty," Maher says. "A number of countries have seen their TB case rates go up threefold or fourfold."
Double whammy
The symbiotic way in which the two infections promote progression to disease and death also fuels the transmission rates. Tuberculosis is not contagious when it’s in a latent form. Because HIV infection causes people also infected with TB to progress rapidly from latent TB infection to full-blown TB disease, it also increases the pool of people who are contagious with TB and therefore spreading it to many others, says Kenneth Castro, MD, director of the Division of TB Elimination at the Centers for Disease Control and Prevention (CDC) in Atlanta.
CDC researchers have found increased viral replication in lymphocytes and macrophages of HIV patients who have active tuberculosis. Co-infection with M. tuberculosis and HIV-1 resulted in a 1,000-fold higher level of viral replication in cells than that seen in a person infected with HIV alone, according to posters presented in June at the Tuberculosis 2000 conference in New York City.
All of the recent research and surveillance data point to a problem that will only escalate unless comprehensive measures are taken to stop the co-infection rate.
"Our responsibility is to declare this situation as intolerable, that the status quo is intolerable, and it calls for action," Castro says. "If nothing is done, it’s only going to get worse."
Coming together
Until recently, health ministries and support organizations tackled each disease separately, rarely working together. WHO and others now recognize that this approach will not succeed. TB organizations need to collaborate with HIV organizations, combating the epidemics with a united front.
"To address the problem, you have to do two things to turn off the TB epidemic," Maher says. "You need to stop TB transmission by identifying and curing the infectious cases using the DOTS strategy, and you need to stop HIV transmission since HIV is fueling TB."
Good collaboration between HIV and TB programs, therefore, is key. In trying to make the solutions to stopping both epidemics widely available, the world’s health community has some new initiatives that should help. WHO, the CDC, UNAIDS, USAID, and other organizations are promoting community-based initiatives aimed at providing testing, treatment, and counseling for people who may have HIV and TB.
While HIV antiretroviral treatment continues to be cost-prohibitive for most people and nations in sub-Saharan Africa, TB treatment is much more affordable, costing as little as $10 to $20. However, the same lack of health care infrastructure that makes HIV testing, counseling, and treatment so elusive in those nations also makes it difficult to treat tuberculosis patients successfully.
Patients need to adhere strictly to the TB medication, sometimes for as long as eight months, for treatment to succeed. Low adherence rates have been associated with a rise in drug-resistant TB strains in many countries. In the United States, this type of strict adherence has been possible among homeless and marginal populations when the drugs are administered in a direct observation therapy program, meaning someone watches the TB patient take the medication each day.
International organizations are working with health ministries in many countries in sub-Saharan Africa to ensure all TB patients have access to the type of support necessary to enable them to adhere to and complete therapy.
One such project, called "Community TB Care in Africa," is investigating how to engage community participation in tackling tuberculosis. Another initiative, called "ProTEST," is investigating how health officials and others may provide interventions designed to prevent HIV infection from fueling the tuberculosis epidemic through voluntary counseling and testing for HIV and other measures.
The Community TB Care in Africa project, begun in 1996, is evaluating the community contribution to effective tuberculosis control in countries with high HIV prevalence. Projects based in districts of Botswana, Kenya, Malawi, South Africa, Uganda, and Zambia began implementing community TB care interventions in early 1998. Their chief intervention is DOTS for people with TB. WHO also provided technical support for community TB projects in Tanzania and Ethiopia. Most pilot sites have demonstrated high rates of treatment success.
Also, the program resulted in lower health care costs for the communities involved. The health systems saw cost savings of between 16% and 72%. The average length of stay for these TB patients dropped by 73% to 98%, and the average family costs also dropped substantially. In Kiboga, the district hospital has closed its TB ward because all of the TB patients were successfully treated in the community, resulting in a considerable cost-savings to the hospital, Maher says.
"Community-member volunteers identified through the parish development committee were doing direct observation therapy," he adds.
The ProTEST initiative is designed to develop a district-based model for the integrated delivery of health care services to reduce the burden of tuberculosis and HIV. ProTEST programs will attempt to reach some of the 90% of people with HIV who do not know they are HIV-positive.
"The program is promoting testing for HIV to make sure those identified with HIV have access to preventive TB treatment if they don’t have TB yet," Maher says.
ProTEST projects are under way in South Africa, Malawi, and Zambia. Uganda is expected to start a project later this year, and Zambia will combine this project with a project that looks at prevention of the transmission of HIV from mother to child.
Community TB Care in Africa Project
| Project site | Intervention cohort (community DOT option) |
Control cohort (no community DOT option) |
Type of control |
| Machakos, Kenya | 90% (537) | 85% (600) | Historical 1996 |
| Lilongwe, Malawi | 68% (1,455) | 61% (914) | Historical 1997 |
| Kiboga, Uganda | 78% (135) | 61% (148) | Historical 1997 |
| Kawempe, Uganda | 52% (298) | 33% (unknown) | Historical 1997 |
| Hlabisa, S. Africa | 86% (37) | 68% (638) | Concurrent |
| Guguletu, S. Africa | 69% (548) | 66% (82) | Concurrent |
| Ndola, Zambia | 77% (40) | 49% (59) | Concurrent |
Source: Dermot Maher, World Health Organization, Communicable Disease Control,
Prevention, and Eradication, TB-LIFE Meeting, Atlanta, Aug. 28-29, 2000.
Percentages (and numbers) represent treatment completion of project
participants.
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