Human Immunodeficiency Virus (HIV) and Invasive Pneumococcal Infections FREE

The pneumococcus is one of many bacteria that attack persons infected with HIV, the virus that causes AIDS. Persons without HIV get pneumococcal infections; however, in areas where many persons are living with HIV, a sizable proportion of invasive infection with this bacterium now occurs in such persons. “Invasive” means that the infection is in a normally bacteria-free area, such as spinal fluid or blood; invasive infections are more serious. Many HIV-related illnesses are decreasing as better treatments for HIV develop, but little is known about what is happening with invasive pneumococcal infection in these patients.

To obtain detailed information about invasive pneumococcal infection in persons with HIV.

Residents of San Francisco County, an area where many HIV-infected persons live.

Every 2 weeks, between October 1994 and June 1997, the researchers contacted the 13 county bacteriology laboratories to identify all cases of invasive pneumococcal infection. They then reviewed the medical records for each case. They used census information to determine how many people lived in the county and information from the county AIDS office to estimate the number who had AIDS.

The researchers found 602 cases of invasive pneumococcal infection. The rates of this infection per 100,000 person-years were greatest for children under 2 (118 cases) and persons over 65 (48 cases). However, the largest total number of cases (399) occurred in adults aged 18 to 64; over half of these were in persons with HIV. The rate of invasive pneumococcal infection was 46 times greater in persons with AIDS than in those without HIV. Blacks and persons in areas with the lowest household incomes were at greatest risk. The rate of invasive pneumococcal infection in persons with AIDS decreased over the study period from 10.6 cases to 4.2 cases per 100,000 person-years. Over 80% of the types of pneumococci found can be protected against by the available pneumococcal vaccine.

The same results may not be found in other geographic areas. The researchers could not be certain that they had identified all people with HIV infection. They also were not able to investigate whether the risk for invasive pneumococcal disease was lower in people who took anti-HIV drugs or were vaccinated against pneumococcus.

A large proportion of all invasive pneumococcal infection currently occurs in persons infected with HIV; black persons and persons with low incomes appear to be at highest risk. Available vaccine can protect against most types of pneumococci found in these invasive infections, but little is known about the effectiveness of the vaccine in HIV-infected persons. Rates of infection decreased between 1994 and 1997, possibly due to better treatment of underlying HIV infection or greater use of pneumococcal vaccine.