1006 GMT April 21, 2019
What's more, of the 39,720 Americans newly diagnosed with HIV in 2015, one-quarter had been infected for seven years or more without knowing they were ill, latimes.com reported.
Among all 1.2 million Americans living with HIV in 2015, the CDC estimated that about 15 percent were unaware of their HIV-positive status. Those people are thought to be responsible for 40 percent of new transmissions of HIV, according to the study published in the CDC's Morbidity and Mortality Weekly Report.
The human immunodeficiency virus, or HIV, is responsible for causing AIDS. Infection used to be considered a death sentence, until antiretroviral medications capable of suppressing the virus came into broad use in the late 1990s.
The new report is the latest measure of how well public health authorities are doing at boosting rates of early diagnosis and care for HIV — goals that will extend life expectancies for patients and reduce the virus' spread.
For each of the new cases diagnosed in 2015, researchers estimated a rough time of infection on the basis of a patient's level of disease progression. Based on patients' initial count of infection-fighting CD4 cells, they gleaned how long the HIV virus likely had replicated unchecked. A normal range for CD4 cells lies between 500 and 1,500; a CD4 count below 200 brings a diagnosis of AIDS.
Although the median time between infection and diagnosis for all Americans was three years, there was considerable variability among patients of different racial and ethnic groups.
For instance, half of African Americans had been infected for 3.3 years when they were diagnosed, while the median time for whites was 2.2 years. This gap was seen despite the fact that African Americans were more likely than whites to have been tested for HIV in the previous year.
For Latinos, the median time to diagnosis was also 3.3 years; for Asian Americans, it was 4.2 years.
Age, a key factor, with older patients more likely than younger ones to go years without knowing they were HIV-positive. Half of newly-diagnosed patients 55 and over were HIV-positive for 4.5 years or more without knowing it. Among those 34 and younger, the median delay between infection and diagnosis was about 2.5 years.
Fully half of people with undiagnosed HIV infection in 2015 were living in the South, the CDC said. States with the highest rates of undiagnosed HIV infection — between 16 percent and 19 percent — included Nevada, Arizona, Texas, Michigan, Iowa, Indiana, North Dakota and Wisconsin. New Jersey, Pennsylvania, Vermont and South Dakota and Idaho had the lowest rates, between 5 percent and 10 percent.
Overall, the three-year gap between infection and diagnosis actually represents progress. In 2011 — the last time the CDC took such measures — half of Americans newly diagnosed with HIV had been infected for 3.6 years or more.