Many US Patients With TB Also HIV-Infected, HIV Testing in US Remains Low, HIV Spread Most by Those With Moderate HIV RNA Level

January 2, 2008
AIDS Reader

The AIDS Reader Vol 18 No 1, Volume 18, Issue 1

Recently the CDC released a report of a study on coinfection with HIV and Mycobacterium tuberculosis that found that many US patients with tuberculosis (TB) are still not being tested for HIV.

Many US Patients With TB Also HIV-Infected
Recently the CDC released a report of a study on coinfection with HIV and Mycobacterium tuberculosis that found that many US patients with tuberculosis (TB) are still not being tested for HIV. Worldwide, TB is the leading opportunistic infection that kills persons who are HIV-positive. In the United States, the CDC recommends routinely testing patients with TB for HIV infection. Patients who are coinfected are 5 times more likely to die during TB treatment than those who are not coinfected, according to the CDC (Dunham W. Reuters. October 26, 2007). "HIV increases TB progression, and TB increases HIV progression. And they result in a synergy that can be deadly," said Suzanne Marks, a CDC epidemiologist and an author of the report.

Analyzing the 1993 to 2005 TB reports from every state but California, the researchers found that 9% of patients with active TB in 2005 were HIV-infected. However, the HIV status remained unknown for 31% of patients with TB, because they either refused HIV testing or were not offered it. In 1993, 65% of US patients with TB were of unknown HIV serostatus.

Of patients who are coinfected with M tuberculosis and HIV, nearly two thirds are black, the authors found. One in 6 black patients with TB also had HIV, compared with 1 in 20 white patients with TB. "High rates of both HIV infection and TB disease among non-Hispanic blacks emphasize the need in this population to prevent, diagnose early, and provide access to care for both conditions," recommended the report. "Increased promotion of routine HIV testing and rapid HIV tests might increase acceptability of testing, which would allow health care providers to know the HIV status of a greater percentage of TB patients and enable them to provide optimal care."

Results of the study were published in the Morbidity and Mortality Weekly Report (2007;56:1103-1106). [CDC HIV/Hepatitis/STD/TB Prevention News Update, Friday, October 26, 2007]

Deadly HIV-TB Co-Epidemic in Sub-Saharan Africa
A report released by the Forum for Collaborative HIV Research stated that HIV and drug-resistant tuberculosis (TB) have combined to undermine efforts to fight the diseases in sub-Saharan Africa and ultimately threaten global eradication efforts. Health care systems overwhelmed by the diseases risk collapse, said the report (Agence France Presse. November 2, 2007).

One third of the world's 40 million HIV-infected persons carry Mycobacterium tuberculosis. Each year, TB will develop in about 10% of immunocompromised patients, and those who are coinfected with HIV and M tuberculosis have 5 times the death rate of those who have only TB, the report said. Of even more concern is that rates of multidrug-resistant TB and extensively drug-resistant TB (XDR TB) are surging in areas where the HIV epidemic is worst.

"Now the eye of the storm is in sub-Saharan Africa, where half of new TB cases are [in persons who are] HIV-coinfected," said Veronica Miller, coauthor of the report and the forum's director. "Unlike bird flu, the global threat of HIV-TB is not hypothetical-it is here now."

"In today's world, a new TB infection occurs every second," said Diane Havlir, head of the World Health Organization's TB/HIV working group. "When one considers that much of this transmission occurs in areas with high HIV prevalence, the imminent danger of a global co-epidemic is clear."

In one small community outside Cape Town, the TB case load increased 6-fold between 1996 and 2004, the report said. "There has been a staggering increase in TB in this community, and this has been replicated right across southern Africa," said Stephen Lawn, a University of Cape Town medical researcher.

The report recommends better coordination among governments, researchers, drug firms, and local communities; faster HIV and TB diagnostic tests for children and adults; new methods to map outbreaks; new screening methods to detect XDR TB; and upgraded laboratory equipment in affected areas. [CDC HIV/Hepatitis/STD/TB Prevention News Update, Friday, November 2, 2007]

HIV Testing in US Remains Low
In any given year, only about one fifth of US residents at high risk for HIV are tested for the virus, new research shows. Many high-risk individuals also say they plan to take the test but fail to follow through (Dunham W. Reuters. October 22, 2007).

"The [AIDS prevention] information is getting out there," said study coauthor Brian Pence, a Duke University epidemiologist. "High-risk groups are appropriately assessing their risk and are interested in testing. And yet there's this gap between intention and action."

The researchers studied the responses of about 147,000 US residents aged 18 to 64 years to CDC health surveys between 2000 and 2005. Ten percent of respondents said they had been tested in the previous year, while 38% reported ever having been tested.

Nineteen percent of those deemed at medium risk were tested in a given year. Among persons whose behavior put them at high risk for infection, 22% were tested in the previous year. Only about half of those tests performed were self-initiated. The rest of the tests were conducted because of insurance examinations, military intake, medical checkups, or other reasons.

Twenty-seven percent of persons at high risk said they planned to have a test in the coming year; however, only 11% of those had sought testing in the previous year.

"Large differences in testing rates according to race and sex remained relatively constant, with minority females reporting the highest rates of testing and white males reporting the lowest rates," the authors wrote.

The fact that nearly half of HIV tests were performed as part of medical checkups or prenatal care suggests that initiatives to make HIV testing a routine part of medical care may be producing results, the researchers said.

The full report, "Trends in HIV Testing and Differences Between Planned and Actual Testing in the United States, 2000-2005," was published in the Archives of Internal Medicine (2007;167:2128-2135). [CDC HIV/Hepatitis/STD/TB Prevention News Update. Friday, October 26, 2007]

HIV Spread Most by Those With Moderate HIV RNA Level
Persons with moderate amounts of HIV in their blood are more likely to transmit the infection, UK and Dutch researchers wrote in a new study (Kahn M. Reuters. October 22, 2007). Looking at a pre-1993 Amsterdam cohort and a Zambian cohort from a 2001 study, the researchers found that those with high HIV RNA levels were more infectious but had less time to transmit the virus to others. The Amsterdam and Zambian studies linked HIV RNA, infectiousness, and survival. In analyzing these studies, the researchers suggest that the virus has evolved to find the optimum mean between infectiousness and virulence, maximizing HIV's transmission potential.

The study focused on patients with medium HIV RNA levels; such patients may be asymptomatic for years before progressing to AIDS. Patients with high HIV RNA levels usually developed AIDS in 2 to 3 years, Fraser said. Persons with medium HIV RNA levels form the largest population of untreated HIV patients, which is also dangerous for onward transmission, researchers said.

Therefore, focusing prevention efforts on those with high HIV RNA levels may not be the most effective public health strategy to stop the spread of AIDS, said Christophe Fraser, an epidemiologist with Imperial College London and the study's senior author. "The surprise was that those people with high viral loads actually infected fewer people because they progressed to AIDS more quickly," said Fraser.

The full report, "Variation in HIV-1 Set-Point Viral Load: Epidemiological Analysis and an Evolutionary Hypothesis," was published in Proceedings of the National Academy of Sciences USA (2007;104:17441-17446).

Many Do Not Think AIDS Is Fatal
While most respondents in a 9-country survey said AIDS is always a fatal illness, many incorrectly believed a cure is available. The research project involved 4510 interviews conducted in the United States, the United Kingdom, Russia, France, China, India, Mexico, Brazil, and South Africa. It was commissioned by the MAC AIDS Fund, a philanthropy established by Estee Lauder's MAC cosmetics company (Brown AJ. ReutersHealth. November 13, 2007).

Among the survey's findings: In India, 59% of those polled believed a cure for HIV infection is available. Nearly half of the respondents believed most persons with HIV are receiving treatment; in fact, 2006 data show only 1 patient in 5 is being treated. Almost half of respondents said they felt uncomfortable walking next to someone with HIV; 52% would not want to live in the same house as a patient; and 79% said they would not want to date someone with the virus. HIV is spreading, in part, because women are uncomfortable discussing safe sex practices with their partners, said 73% of respondents.

"When people believe the disease is not fatal and that there is a cure, that's because we haven't educated them well," said Dr Marsha Martin, director of HIV/AIDS programs in the office of the mayor of Oakland, Calif.

"The results of this survey, coupled with the recent failure of the most promising AIDS vaccine trial, underscore that we are not going to vaccinate or cure our way out of this epidemic," said Nancy Mahon, the MAC AIDS Fund's executive director. "All of us, particularly in the funding community, need to redouble our efforts and resources and focus on basic and effective HIV prevention programs that address gender, age, and race differences in a direct and culturally competent way." [CDC HIV/Hepatitis/STD/TB Prevention News Update, Friday, November 16, 2007]

Genetic Factor in AIDS Progression Is Higher Than Thought
A recent study found that 2 genes are important in determining the pace of HIV-infected patients' progress to AIDS (Agence France Presse. October 22, 2007). The researchers say the finding challenges the notion that HIV RNA level and its effect on the immune system are the chief drivers of an HIV-positive person's progression to AIDS. The study's authors say that genes encoding the immune cell coreceptor CCR5 and chemokine CCL3L1, and possibly others, also play a part in the course of infection.

The CCR5 receptor is a key immune cell surface docking point by which HIV infects the cell. CCL3L1 controls an immune system signaling molecule that blocks HIV from attaching to CCR5.

In 2005, Dr Sunil Ahuja, of The University of Texas Health Science Center, and colleagues found that persons with extra copies of CCL3L1 are less likely to become infected with HIV, and those with CCR5 mutations have been found to have protection against HIV infection. In their latest work, Ahuja and colleagues ranked 3500 US HIV-infected and -uninfected patients according to their number of favorable and unfavorable CCR5 mutations and CCL3L1 copies and analyzed disease progression and health among the participants.

HIV RNA level at early stages of infection accounted for 9% of the difference in rate of disease progression to AIDS, according to the researchers. But just as important was the sort of combination of the genes. "The genetic variations contribute nearly as much to the extent of inter-individual variability in AIDS progression rates as does HIV-1 viral load," Ahuja said.

"Even accounting for the detrimental effects of a high viral burden, these genetic factors influence the pace of HIV-1 disease progression," said Hemant Kulkarni, a coauthor of the study and an assistant professor at The University of Texas. The genes also affected the immune response of uninfected persons, suggesting they may play a role in how the body responds to other diseases.

The full study, "CCL3L1 and CCR5 Influence Cell-Mediated Immunity and Affect HIV-AIDS Pathogenesis via Viral Entry-Independent Mechanisms," was published online in Nature Immunology (2007;doi:10.1038/ni1521). [CDC HIV/Hepatitis/STD/TB Prevention News Update, Friday, November 9, 2007]

Some OB/GYNs Unclear on HIV Testing Requirements
A survey of obstetrician/gynecologists (OB/GYNs) regarding HIV knowledge found that while most recommend HIV testing to their pregnant patients, some are unaware of their state's requirements for recommending such testing (Reuters. November 16, 2007).

The CDC recommends that all pregnant women receiving prenatal care be tested for HIV using an opt-out approach, in which the patient is provided with information on HIV and told that a test will be conducted as part of other standard testing unless she declines.

Dr Jay Schulkin and colleagues sent out 1032 questionnaires, of which 582 were returned. All but 3% of OB/GYNs reported they recommend HIV testing, although nearly three quarters considered 5% or fewer of their patients to be at high risk for HIV. Just over half (57%) reported using the testing approach required by their states, while 43% reported using an approach not consistent with their state's guidelines. Almost one third of the OB/GYNs said they did not know whether their state required HIV testing during pregnancy.

OB/GYNs were about evenly divided as to which testing approach they used, with 52% using the opt-in method and 48% reporting the opt-out approach. Most provided pretest counseling (74%) and posttest counseling (85%).

"The results of this study suggest that [OB/GYNs] may benefit from additional information that could improve their knowledge and practice regarding HIV screening," the researchers said. "Although most respondents report being at least moderately knowledgeable about HIV during pregnancy and report recommending HIV testing to all pregnant patients, they may need to be more aggressive in following up with patients who decline HIV testing," they concluded.

Results of the study were published in Obstetrics & Gynecology (Gray AD, Carlson R, Morgan MA, et al. Obstet Gynecol. 2007;110:1019-1026). [CDC HIV/Hepatitis/ STD/TB Prevention News Update, Wednesday, November 21, 2007]

Related Content:

News