Utilizing data from a recent study of tuberculosis (TB) cases among foreign-born persons in the United States, this news article, published in the Journal of the American Medical Association, highlights the changing epidemiological trends in tuberculosis (TB) cases in the United States.¹ Despite the fact that TB cases among US-born residents between 1993 and 2004 fell by 62%, cases among foreign-born residents rose by 5% during the same time period, growing from 29% to 54% of total cases. Notably, of all the reported cases among foreign-born residents in 2004, about half had lived in the United States for at least five years. The increasing proportion of cases among foreign-born individuals who have lived in the United States for more than five years renders existing recommendations, which call for tuberculin skin testing and treatment of latent infections only among those who have lived in the United States for less than five years, obsolete. While new guidelines are under review, many experts, the article suggests, fear that rising cases in immigrant populations together with cutbacks in state and federal TB-control programs could create a resurgence in TB cases, similar to that seen in the United States in the late 1980s and early 1990s.

In this study, originally published in MMWR, investigators examined opportunities to detect HIV infection among all cases of HIV and AIDS reported in South Carolina prior to the 2006 release of revised CDC guidelines for HIV testing in health-care settings. Of the 4,315 reported cases of HIV infection from 2001-2005, 41% were late-testers, defined as persons in whom AIDS was diagnosed within one year of the initial HIV diagnosis. By linking data from the South Carolina HIV/AIDS Reporting System (HARS) and the South Carolina Office of Research and Statistics (ORS), the investigators were able to determine that 73% of the late-testers had made at least one documented visit to a South Carolina health-care facility between 1997 and 2005. In total, these late-testers made 7,988 visits to various facilities such as emergency departments (79.9%), inpatient settings (12.3%), outpatient facilities (7.4%), and free clinics (1.4%). 79% of the resulting diagnoses were categorized as not likely to be suggestive of an HIV infection, even though 33.9% of the late-testers were identified as persons with high risk practices that should have prompted HIV screening if risk histories had been elicited. These findings, the authors assert, suggest that routine, opt-out HIV screening of all patients, rather than risk based testing, might result in substantially earlier HIV diagnoses in South Carolina.

In an accompanying editorial, authors from the CDC note that the findings from the South Carolina study support the new recommendations for routine, opt-out HIV screening in all health care settings. Additionally, they highlight the fact that a substantial proportion of the newly diagnosed HIV cases in 2004-2005 had low CD4+ cell counts, suggesting a high prevalence and long duration of undiagnosed HIV infections in South Carolina. In considering the limitations of the report, the members of the CDC point out that certain HIV/AIDS diagnoses may not have been reported to HARS/ORS, the matching of records might not have been successful in all cases, patients might have rejected HIV testing, and certain late-testers may not have been HIV infected during the time of their health care visits. In conclusion, they remark that the capacity of treatment and preventive services in South Carolina will need to increase if HIV testing is made routine.

Researchers in Switzerland, an area with low rates of TB transmission, assessed the effect of tuberculin skin testing (TST) and preventive treatment on the incidence of tuberculosis (TB). Using data from the more than six thousand participants in the Swiss HIV Cohort Study (SHCS), the investigators calculated a TB incidence of 0.22 cases per 100 person-years in the overall study population. Among the 69% of individuals who received TST, 9.4% had positive results. Significantly, if preventive treatment was not administered, the incidence of TB was found to be 1.6 cases per 100 person-years in those patients with positive TST results. In contrast, none of the 193 TST positive patients who received preventive treatment developed TB. Increased risk for TB in the study population included: positive TST results, missing TST results, origin from sub-Saharan Africa, low CD4+ cell counts, and high plasma HIV RNA levels. Those patients receiving combination antiretroviral therapy were at a reduced risk. The authors suggest that potential study limitations include an underestimation of TB incidence due to the short follow-up period of two years and possible delay between the diagnosis of HIV or TB and registration in SHCS. Nonetheless, the investigators conclude that screening for latent TB using TST and preventive treatment for patients with positive TST results remains an efficacious strategy for reducing TB-associated morbidity in a country with low rates of TB transmission.