Infectious Diseases - Hiv/aids

AIDS is the late stage of an infection caused by HIV, a retrovirus that attacks and destroys certain white blood cells, which weakens the body's immune system and makes it susceptible to infections and diseases that ordinarily would not be life threatening. AIDS is considered a bloodborne, sexually transmitted disease because HIV is spread through contact with blood, semen, or vaginal fluids from an infected person.

Around the World

AIDS and HIV were virtually unknown before 1981, when testing and reporting of the disease became mandatory, but awareness grew as the annual number of diagnosed cases and deaths steadily increased. By 2006 more than forty million people worldwide were estimated to be living with HIV/AIDS, according to the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the WHO. Of those infected, thirty-eight million were adults and about 2.3 million were children younger than age fifteen. Nearly five million people were newly infected with the virus in 2005. Two-thirds of all people infected with HIV lived in sub-Saharan Africa. In 2005 an TABLE 7.5 Reported tuberculosis cases and deaths, 1953–2004 "Table 1. Tuberculosis Cases, Case Rates per 100,000 Population, Deaths, and Death Rates per 100,000 Population, and Percent Change: United States, 1953–2004,"in Reported Tuberculosis in the United States, 2004, Centers for Disease Control and Prevention, National Center for HIV, STD, and TB Prevention, Division of Tuberculosis Elimination, 2005, http://www.cdc.gov/nchstp/tb/surv/surv2004/PDF/Table1.pdf (accessed January 29, 2006)estimated 25.8 million people in this region were living with HIV, and AIDS killed approximately 2.4 million people in the region the same year. Unlike women in other regions in the world, African women are much more likely (about twice as much) than men to be infected with HIV—more than three-quarters (77%) of all women infected with HIV are in sub-Saharan Africa ("AIDS Epidemic Update," UNAIDS, WHO, December 2005, http://www.unaids.org/epi/2005/doc/report_pdf.asp).

TABLE 7.5
Reported tuberculosis cases and deaths, 1953–2004
Year	Tuberculosis cases				Tuberculosis deaths
	Number	Rate	Percent change		Number	Rate	Percent change
			Number	Rate			Number	Rate
*The large decrease in death rate in 1979 occurred because late effects of tuberculosis (e.g., bronchiectasis or fibrosis) and pleurisy with effusion (without mention of cause) are no longer included in tuberculosis deaths.
Note: "—"= Data not available. Case data after 1974 are not comparable to prior years due to changes in the surveillance case definition that became effective in 1975.
SOURCE: "Table 1. Tuberculosis Cases, Case Rates per 100,000 Population, Deaths, and Death Rates per 100,000 Population, and Percent Change: United States, 1953–2004,"in Reported Tuberculosis in the United States, 2004, Centers for Disease Control and Prevention, National Center for HIV, STD, and TB Prevention, Division of Tuberculosis Elimination, 2005, http://www.cdc.gov/nchstp/tb/surv/surv2004/PDF/Table1.pdf (accessed January 29, 2006)
1953	84,304	52.6	—	—	19,707	12.4	—	—
1954	79,775	48.9	−5.4	−7.0	16,527	10.2	−16.1	−17.7
1955	77,368	46.6	−3.0	−4.7	15,016	9.1	−9.1	−10.8
1956	69,895	41.4	−9.7	−11.1	14,137	8.4	−5.9	−7.7
1957	67,149	39.0	−3.9	−5.8	13,390	7.8	−5.3	−7.1
1958	63,534	36.3	−5.4	−6.9	12,417	7.1	−7.3	−9.0
1959	57,535	32.4	−9.4	−10.7	11,474	6.5	−7.6	−8.5
1960	55,494	30.7	−3.5	−5.2	10,866	6.0	−5.3	−7.7
1961	53,726	29.2	−3.2	−4.2	9,938	5.4	−8.5	−10.0
1962	53,315	28.6	−0.8	−2.7	9,506	5.1	−4.3	−5.6
1963	54,042	28.6	+1.4	0.0	9,311	4.9	−2.1	−3.9
1964	50,874	26.5	−5.9	−7.3	8,303	4.3	−10.8	−12.2
1965	49,016	25.2	−3.7	−4.9	7,934	4.1	−4.4	−4.7
1966	47,767	24.3	−2.5	−3.6	7,625	3.9	−3.9	−4.9
1967	45,647	23.0	−4.4	−5.3	6,901	3.5	−9.5	−10.3
1968	42,623	21.2	−6.6	−7.8	6,292	3.1	−8.8	−11.4
1969	39,120	19.3	−8.2	−9.0	5,567	2.8	−11.5	−9.7
1970	37,137	18.1	−5.1	−6.2	5,217	2.6	−6.3	−7.1
1971	35,217	17.0	−5.2	−6.0	4,501	2.2	−13.7	−15.4
1972	32,882	15.7	−6.6	−7.6	4,376	2.1	−2.8	−4.5
1973	30,998	14.6	−5.7	−7.0	3,875	1.8	−11.4	−14.5
1974	30,122	14.1	−2.8	−3.4	3,513	1.7	−9.3	−5.6
1975	33,989	15.7	—	—	3,333	1.6	−5.1	−5.9
1976	32,105	14.7	−5.5	−6.4	3,130	1.5	−6.1	−6.3
1977	30,145	13.7	−6.1	−6.8	2,968	1.4	−5.2	−6.7
1978	28,521	12.8	−5.4	−6.6	2,914	1.3	−1.8	−7.1
1979	27,669	12.3	−3.0	−3.9	2,007*	0.9*	−31.1*	−30.8*
1980	27,749	12.2	+0.3	−1.0	1,978	0.9	−1.4	0.0
1981	27,373	11.9	−1.4	−2.3	1,937	0.8	−2.1	−11.1
1982	25,520	11.0	−6.8	−7.6	1,807	0.8	−6.7	0.0
1983	23,846	10.2	−6.6	−7.3	1,779	0.8	−1.5	0.0
1984	22,255	9.4	−6.7	−7.8	1,729	0.7	−2.8	−12.5
1985	22,201	9.3	−0.2	−1.1	1,752	0.7	+1.3	0.0
1986	22,768	9.5	+2.6	+1.1	1,782	0.7	+1.7	0.0
1987	22,517	9.3	−1.1	−2.1	1,755	0.7	−1.5	0.0
1988	22,436	9.2	−0.4	−1.0	1,921	0.8	+9.5	+14.3
1989	23,495	9.5	+4.7	+3.3	1,970	0.8	+2.6	0.0
1990	25,701	10.3	+9.4	+8.4	1,810	0.7	−8.1	−12.5
1991	26,283	10.4	−2.3	−1.0	1,713	0.7	−5.4	0.0
1992	26,673	10.5	+1.5	+1.0	1,705	0.7	−0.5	0.0
1993	25,108	9.7	−5.9	−7.1	1,631	0.6	−4.3	−14.3
1994	24,205	9.2	−3.6	−4.8	1,478	0.6	−9.4	0.0
1995	22,727	8.5	−6.1	−7.2	1,336	0.5	−9.6	−16.7
1996	21,211	7.9	−6.7	−7.7	1,202	0.5	−10.0	0.0
1997	19,751	7.2	−6.9	−8.0	1,166	0.4	−3.0	−20.0
1998	18,287	6.6	−7.4	−8.5	1,112	0.4	−4.6	0.0
1999	17,501	6.3	−4.3	−5.4	930	0.3	−16.4	−25.0
2000	16,309	5.8	−6.8	−7.8	776	0.3	−16.6	0.0
2001	15,945	5.6	−2.2	−3.2	764	0.3	−1.6	0.0
2002	15,057	5.2	−5.6	−6.5	784	0.3	+2.6	0.0
2003	14,852	5.1	−1.4	−2.3	704	0.2	−10.2	−33.3
2004	14,517	4.9	−2.3	−3.2	—	—	—	—

Since the epidemic began, more than twenty-five million people have died of AIDS; more than three million died in 2005 alone. Of those, more than half a million were children.

TABLE 7.6 Number and rate of tuberculosis cases and percentage change, by race/ethnicity and year, 2003 and 2004 "Table. Number and Rate of Tuberculosis Cases and Percentage Change, by Race/Ethnicity and Year—United States, 2003 and 2004, "in "Trends in Tuberculosis—United States, 2004," Morbidity and Mortality Weekly Report, vol. 54, no. 10, March 18, 2005, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, http://iier.isciii.es/mmwr/preview/mmwrhtml/mm5410a2.htm (accessed January 17, 2006)

TABLE 7.6
Number and rate of tuberculosis cases and percentage change, by race/ethnicity and year, 2003 and 2004
Race/ethnicity	2003		2004b		Percent change		U.S. population
					2003–2004b
	Number	Ratea	Number	Ratea	Number	Ratea	2003	2004b
aPer 100,000 population.
bData for 2004 are provisional.
cPersons included in this category are American Indian/Alaska Native (2004, number=159, rate: 7.2 per 100,000 population; 2003, number=177, rate: 8.1), Native Hawaiian or other Pacific Islander, multiple race (2004, number=47, rate: 1.2; 2003, number=36, rate: 1.0), and unknown race. The race category for Native Hawaiian or other Pacific Islander was first introduced in 2003, and the rates are not listed using provisional data.
SOURCE: "Table. Number and Rate of Tuberculosis Cases and Percentage Change, by Race/Ethnicity and Year—United States, 2003 and 2004," in "Trends in Tuberculosis—United States, 2004," Morbidity and Mortality Weekly Report, vol. 54, no. 10, March 18, 2005, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, http://iier.isciii.es/mmwr/preview/mmwrhtml/mm5410a2.htm (accessed January 17, 2006)
Hispanic	4,109	10.3	4,160	10.1	+1.2%	−2.3%	39,898,889	41,329,556
Non-Hispanic
Black	4,153	11.7	4,006	11.1	−3.5%	−4.6%	35,593,148	35,980,588
Asian	3,441	29.5	3,253	26.9	−5.5%	−8.6%	11,673,494	12,080,429
White	2,797	1.4	2,638	1.3	−5.7%	−5.9%	197,326,272	197,768,300
Other/unknowna	358		454
Total	14,858	5.1	14,511	4.9	−2.3%	−3.3%	290,809,777	293,622,764

In the United States

The CDC reports in HIV/AIDS Surveillance Report, 2004 (http://www.cdc.gov/hiv/stats/2004Surveillance Report.pdf) that by December 2004 there were an estimated 462,792 persons in the United States living with HIV/AIDS, in the thirty-five areas with confidential name-based HIV infection reporting since 2000. Of all HIV infections diagnosed in 2003, 39% progressed to AIDS within twelve months after HIV infection was diagnosed. In 2003 an estimated 43,171 diagnoses of AIDS in the United States were made. Adult and adolescent AIDS cases totaled 43,112, with 31,614 cases in males and 11,498 cases in females, and an estimated fifty-nine AIDS cases were diagnosed in children under age thirteen.

The HIV/AIDS Surveillance Report, 2004 also notes that from 2000 through 2004 the estimated number of AIDS cases increased about 7% among males and 10% among females. In 2004 males accounted for nearly three-quarters (73%) of all HIV/AIDS cases among adults and adolescents. Rates of AIDS cases in 2004 were 25.6 per one hundred thousand among males and nine per one hundred thousand among females. (See Table 7.7.) Since its recognition in 1981, the disease has killed more than half a million people in the United States.

How Is AIDS Spread?

HIV/AIDS is not transmitted through casual contact with an infected person. The CDC has identified several behavioral risk factors that greatly increase the likelihood of a person's chances of being infected. Table 7.8 shows the estimated numbers of those diagnosed with AIDS by year of diagnosis and selected characteristics of patients, including the ways in which they contracted the disease.

More than twenty-five years of research and observation have definitively concluded that the HIV infection can only be transmitted by the following methods:

• By oral, anal, or vaginal sex with an infected person; worldwide, heterosexual sex is the most common mode of transmission
• By sharing drug needles or syringes with an infected person
• From an infected mother to her baby at the time of birth and possibly through breast milk
• By receiving a transplanted organ or bodily fluids, such as blood transfusions or blood products, from an infected person

Because avoiding these methods of transmission virtually eliminates the possibility of becoming infected with HIV, unlike some other infectious diseases, AIDS is considered almost entirely preventable.

High concentrations of HIV have been found in blood, semen, and cerebrospinal fluid. Concentrations one thousand times less have been found in saliva, tears, vaginal secretions, breast milk, and feces. There have been no reports, however, of HIV transmission from saliva, tears, or human bites. In fact, in 1995 the National Institute of Dental Research in Bethesda, Maryland, reported that a small protein found in human saliva actually blocks the virus from entering the system.

Opportunistic Infections

Once HIV has destroyed the immune system, the body can no longer protect itself against bacterial, fungal, parasitic, or viral agents that take advantage of the compromised condition, causing opportunistic FIGURE 7.1 Number and rate of persons with tuberculosis (TB) by origin of birth and year, 1993–2004 "Figure 2. Number and Rate of Persons with Tuberculosis (TB), by Origin of Birth and Year—United States, 1993–2004," in "Trends in Tuberculosis—United States, 2004," Morbidity and Mortality Weekly Report, vol. 54, no. 10, March 18, 2005, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, http://iier.isciii.es/mmwr/preview/mmwrhtml/mm5410a2.htm (accessed January 17, 2006)infections (OIs). OIs are illnesses caused by organisms that would not normally harm a healthy person. Because the patient is considered to have AIDS if at least one OI appears, OIs are considered "AIDSdefining events." OIs are not the only AIDS-defining events; the diagnosis of malignancies such as Kaposi's sarcoma, Burkitt's lymphoma, invasive cervical cancer, and primary brain lymphoma also are considered AIDS-defining events.

One of the most common opportunistic infections is Pneumocystis carinii pneumonia, a lung infection caused by a fungus. Other infections to which patients with AIDS are susceptible are toxoplasmosis (a contagious disease caused by a one-cell parasite); oral candidiasis (thrush); esophageal or bronchial candidiasis; extrapulmonary cryptococcosis; pulmonary TB; extrapulmonary TB; Mycobacterium avium complex (MAC), a serious bacterial infection that can occur in one part of the body, TABLE 7.7 Estimated numbers of cases and rates (per 100,000 population) of AIDS, by race/ethnicity, age category, and sex, 2004 "Table 5a. Estimated Numbers of Cases and Rates (per 100,000 population) of AIDS, by Race/Ethnicity, Age Category, and Sex, 2004—50 States and the District of Columbia,"in HIV/AIDS Surveillance Report, 2004, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2005, http://www.cdc.gov/hiv/stats/2004SurveillanceReport.pdf (accessed January 17, 2006)such as the liver, bone marrow, and spleen, or can spread throughout the body; and cytomegalovirus disease (CMV), a member of the herpes virus group.

TABLE 7.7
Estimated numbers of cases and rates (per 100,000 population) of AIDS, by race/ethnicity, age category, and sex, 2004
Race/ethnicity	Adults or adolescents						Children (<13 yrs)		Total
	Males		Females		Total
	Number	Rate	Number	Rate	Number	Rate	Number	Rate	Number	Rate
Note: These numbers do not represent reported case counts. Rather, these numbers are point estimates, which result from adjustments of reported case counts. The reported case counts are adjusted for reporting delays. The estimates do not include adjustment for incomplete reporting. Data exclude cases from the U.S. dependencies, possessions, and associated nations, as well as cases in persons whose state or area of residence is unknown, because of the lack of census information by race and age categories for these areas.
*Includes persons of unknown race or multiple races. Total includes 183 persons of unknown race or multiple races. Because column totals were calculated independently of the values for the subpopulations, the values in each column may not sum to the column total.
SOURCE: "Table 5a. Estimated Numbers of Cases and Rates (per 100,000 population) of AIDS, by Race/Ethnicity, Age Category, and Sex, 2004—50 States and the District of Columbia,"in HIV/AIDS Surveillance Report, 2004, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2005, http://www.cdc.gov/hiv/stats/2004SurveillanceReport.pdf (accessed January 17, 2006)
White, not Hispanic	10,118	12.3	1,860	2.1	11,978	7.1	7	0.0	11,985	6.0
Black, not Hispanic	13,398	99.4	7,395	48.2	20,793	72.1	29	0.4	20,822	56.4
Hispanic	6,041	37.9	1,643	11.1	7,684	25.0	7	0.1	7,691	18.6
Asian/Pacific Islander	392	7.5	92	1.6	484	4.4	1	0.1	486	3.7
American Indian/Alaska Native	128	13.5	64	6.4	192	9.9	1	0.2	193	7.9
Total*	30,203	25.6	11,109	9.0	41,312	17.1	46	0.1	41,359	14.1

Treatment of AIDS

The first drug thought to delay symptoms was zidovudine (earlier known as AZT, later as ZDV), but its effects have been found to be temporary at best. Several other drugs work on the same principle as ZDV, but until the advent of protease inhibitors (PIs), a class of drugs that became available in the mid-1990s, it seemed that there was no way of stopping HIV. Protease inhibitors appear to keep HIV from reproducing, unlike ZDV and similar drugs, which help keep HIV out of the cell's chromosomes. Even if the PIs are not entirely effective long term in reducing patients' viral "loads," they have improved patients' prospects simply by creating more roadblocks for HIV. Unfortunately, HIV mutates so rapidly that it eventually becomes resistant to most drugs when they are used alone.

Treatment recommendations change rapidly in response to the development of new drugs and clinical trials indicating the effectiveness of different combinations of antiretroviral drugs. Researchers are acting quickly to develop new mixtures of the recently approved and older drugs. Because HIV mutates to resist any drug it faces, including all PIs, researchers have found that varying the combination of drugs prescribed can "fool" the virus before it has time to mutate.

Still, there are reasons for optimism in the battle against HIV/AIDS. The CDC reports in Emerging Infectious Diseases that since the use of combinations of drugs that target different proteins involved in HIV pathogenesis (a treatment strategy known as highly active antiretroviral therapy or HAART), rates of death and illness in the United States and other industrialized countries have been dramatically reduced—the death rate due to HIV/AIDS in Europe and North America has fallen by 80%. As of 2006 more than twenty antiretroviral medications were approved by the FDA that target HIV, and researchers were pursuing novel strategies for prevention and vaccine development. Although the first large-scale trial of an HIV vaccine reported in 2003 was disappointing, as of 2006 there were fifteen clinical trials of different vaccine strategies underway, including viral and bacterial vectors, DNA vaccines, virus-like particle vaccines, and peptide vaccines. Even if a cure for the disease is not imminent, new and better drugs used in various combinations have made HIV infection a chronic but manageable disease, much like diabetes.

COMPLICATIONS, COSTS, AND SIDE EFFECTS OF TREATMENT

Patients undergoing therapy with these anti-retroviral drugs or drug combinations must be highly disciplined. For instance, Crixivan must be taken on an empty stomach, every eight hours, not less than two hours before or after a meal, and with large amounts of water to prevent development of kidney stones. Patients also must be careful never to skip doses of Crixivan; otherwise, HIV will quickly grow immune to its effect. (Crixivan has been found to generate cross-resistance, meaning it made patients resistant to other PIs.) Invirase must be taken in large doses. Norvir must be carefully prescribed and administered because it interacts negatively with some antifungals and antibiotics used by patients with AIDS. Because there are a variety of minor and serious risks associated with use of these drugs, patients must be closely monitored by health care practitioners.

The drug regimens are complicated, produce severe side effects in a substantial number of patients, and are TABLE 7.8 Estimated numbers of AIDS cases, by year of diagnosis and selected characteristics of persons, 2000–04 "Table 3. Estimated Numbers of AIDS Cases, by Year of Diagnosis and Selected Characteristics of Persons, 2000–2004—United States," in HIV/AIDS Surveillance Report, 2004, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2005, http://www.cdc.gov/hiv/stats/2004SurveillanceReport.pdf (accessed January 17, 2006)costly. The cost of protease inhibitors, such as Viracept and Crixivan, ranges from $4,800 to $8,000 for a year's supply. When combined with ZDV or any of the other commonly used antiretroviral drugs—such as lamivudine (3TC), zalcitabine (ddC), didanosine (ddI), or stavudine (d4T)—the cost is approximately $18,000 per year. Lifetime treatment costs for HIV/AIDS are estimated to be in excess of $155,000. According to Benjamin Young, MD, PhD, of the University of Colorado School of Medicine, the cost of HAART varies from $1,000 to $2,000 per month. Dr. Young observed that many variables are involved in calculating the actual cost to the

TABLE 7.8
Estimated numbers of AIDS cases, by year of diagnosis and selected characteristics of persons, 2000–04
	Year of diagnosis					Cumulative through 2004a
	2000	2001	2002	2003	2004
Note: These numbers do not represent reported case counts. Rather, these numbers are point estimates, which result from adjustments of reported case counts. The reported case counts are adjusted for reporting delays and for redistribution of cases in persons initially reported without an identified risk factor. The estimates do not include adjustment for incomplete reporting.
aIncludes persons with a diagnosis of AIDS from the beginning of the epidemic through 2004.
bIncludes hemophilia, blood transfusion, perinatal, and risk factor not reported or not identified.
cIncludes hemophilia, blood transfusion, and risk factor not reported or not identified.
dIncludes persons of unknown race or multiple races and persons of unknown sex. Cumulative total includes 2,308 persons of unknown race or multiple races and 2 persons of unknown sex. Because column totals were calculated independently of the values for the subpopulations, the values in each column may not sum to the column total.
SOURCE: "Table 3. Estimated Numbers of AIDS Cases, by Year of Diagnosis and Selected Characteristics of Persons, 2000–2004—United States," in HIV/AIDS Surveillance Report, 2004, U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2005, http://www.cdc.gov/hiv/stats/2004SurveillanceReport.pdf (accessed January 17, 2006)
Age at diagnosis (years)
<13	124	115	109	69	48	9,443
13-14	60	79	71	58	60	959
15-19	291	274	312	301	326	4,936
20-24	1,329	1,343	1,467	1,664	1,788	34,164
25-29	3,432	3,239	3,279	3,276	3,576	114,642
30-34	6,497	6,258	6,010	6,003	5,786	195,404
35-39	8,930	8,649	8,716	8,763	8,031	208,199
40-44	7,530	7,502	7,825	8,291	8,747	161,964
45-49	5,200	5,401	5,656	6,102	6,245	99,644
50-54	3,007	3,199	3,436	3,672	3,932	54,869
55-59	1,528	1,567	1,718	1,854	2,079	29,553
60-64	833	820	930	929	996	16,119
≥65	752	759	738	848	901	14,410
Race/ethnicity
White, not Hispanic	11,378	11,052	11,604	11,657	12,013	375,155
Black, not Hispanic	19,510	19,473	19,934	20,685	20,965	379,278
Hispanic	7,957	7,974	7,907	8,632	8,672	177,164
Asian/Pacific Islander	350	381	440	478	488	7,317
American Indian/Alaska Native	175	169	186	189	193	3,084
Transmission category
Male adult or adolescent
Male-to-male sexual contact	15,374	15,510	16,442	17,139	17,691	441,380
Injection drug use	7,036	6,447	6,247	6,213	5,968	176,162
Male-to-male sexual contact and injection drug use	2,102	2,056	1,982	1,996	1,920	64,833
Heterosexual contact	4,162	4,440	4,771	4,967	5,149	59,939
Otherb	300	290	288	263	298	14,085
Subtotal	28,974	28,743	29,730	30,578	31,024	756,399
Female adult or adolescent
Injection drug use	3,393	3,175	3,008	3,068	3,184	72,651
Heterosexual contact	6,785	6,930	7,181	7,859	7,979	99,175
Otherb	237	243	240	257	279	6,636
Subtotal	10,415	10,348	10,429	11,184	11,442	178,463
Child (<13 years at diagnosis)
Perinatal	122	113	105	68	47	8,779
Otherc	2	3	4	1	0	664
Subtotal	124	115	109	69	48	9,443
Region of residence
Northeast	12,105	11,212	10,395	11,149	11,158	289,792
Midwest	3,968	3,949	4,303	4,495	4,498	93,701
South	15,841	16,598	17,751	18,612	19,792	343,449
West	6,443	6,258	6,745	6,474	6,083	187,730
U.S. dependencies, possessions, and associated nations	1,156	1,190	1,073	1,100	982	29,634
Totald	39,513	39,206	40,267	41,831	42,514	944,306

individual—insurance coverage, governmental assistance programs, and pharmaceutical company patient-assistance programs. For some patients, drug clinical trials offer access to these costly medications ("The Cost of HAART," in "Ask the Experts about Choosing Your Meds," The Body.com, http://www.thebody.com/Forums/AIDS/Starting/Current/Q140963.html). Government programs and private insurers alike are looking for ways to pay for, and in some cases, avoid paying for, these new therapies.

NEW, MORE EFFICIENT HIV TREATMENT

In January 2006, an international team of AIDS researchers determined that a once-daily combination of three antiretroviral drugs is more effective as initial treatment for HIV infection than the previous and widely used three-drug combination. The researchers found that after one year of treatment, a regimen of antiretroviral pills, called tenofovir DF (Viread) and emtricitabine (Emtriva), plus efavirenz (Sustiva), improved patients' ability to suppress the virus by 14%. Even more promising, the new regimen produced fewer side effects and researchers were optimistic that the simpler, more convenient regimen would encourage more people to seek treatment and increase adherence to prescribed treatment (Joel E. Gallant et al, "Tenofovir DF, Emtricitabine, and Efavirenz vs. Zidovudine, Lamivudine, and Efavirenz for HIV," New England Journal of Medicine, vol. 354, no. 3, January 19, 2006, http://content.nejm.org/cgi/content/abstract/354/3/251).

HIV and Tuberculosis

TB occurs with increasing frequency among people infected with HIV. In fact, HIV infection has become one of the strongest known risk factors for the progression of TB from infection to disease. A 1996 report from the Conference on Retroviruses and Opportunistic Infections concluded that the decline in CD4+ T-cells is greater in patients with HIV who develop TB than in those who remain free of the disease. In some geographic areas as many as 58% of people with TB were HIV-positive. Figure 7.2 shows the estimated percent of persons ages twenty-five to forty-four with TB that also are infected with HIV from 1993 to 2003.

Of the many diseases associated with HIV infection, TB is one of the few that is transmissible, treatable, and preventable. It is important to note that HIV is a blood-borne infection and cannot be spread through air. A person with HIV who has TB can spread TB nuclei through the air, but they cannot spread HIV this way.