HIV Infection and the Epidemiology of Invasive Pneumococcal Disease (IPD) in South African Adults and Older Children Prior to the Introduction of a Pneumococcal Conjugate Vaccine (PCV)

Abstract

IntroductionStreptococcus pneumoniae is the commonest cause of bacteremic pneumonia among HIV-infected persons. As more countries with high HIV prevalence are implementing infant pneumococcal conjugate vaccine (PCV) programs, we aimed to describe the baseline clinical characteristics of adult invasive pneumococcal disease (IPD) in the pre-PCV era in South Africa in order to interpret potential indirect effects following vaccine use.MethodsNational, active, laboratory-based surveillance for IPD was conducted in South Africa from 1 January 2003 through 31 December 2008. At 25 enhanced surveillance (ES) hospital sites, clinical data, including HIV serostatus, were collected from IPD patients ≥ 5 years of age. We compared the clinical characteristics of individuals with IPD in those HIV-infected and -uninfected using multivariable analysis. PCV was introduced into the routine South African Expanded Program on Immunization (EPI) in 2009.ResultsIn South Africa, from 2003–2008, 17 604 cases of IPD occurred amongst persons ≥ 5 years of age, with an average incidence of 7 cases per 100 000 person-years. Against a national HIV-prevalence of 18%, 89% (4190/4734) of IPD patients from ES sites were HIV-infected. IPD incidence in HIV-infected individuals is 43 times higher than in HIV-uninfected persons (52 per 100 000 vs. 1.2 per 100 000), with a peak in the HIV-infected elderly population of 237 per 100 000 persons. Most HIV-infected individuals presented with bacteremia (74%, 3 091/4 190). HIV-uninfected individuals were older; and had more chronic conditions (excluding HIV) than HIV-infected persons (39% (210/544) vs. 19% (790/4190), p<0.001). During the pre-PCV immunization era in South Africa, 71% of serotypes amongst HIV-infected persons were covered by PCV13 vs. 73% amongst HIV-uninfected persons, p = 0.4, OR 0.9 (CI 0.7–1.1).ConclusionSeventy to eighty-five percent of adult IPD in the pre-PCV era were vaccine serotypes and 93% of cases had recognized risk factors (including HIV-infection) for pneumococcal vaccination. These data describe the epidemiology of IPD amongst HIV-infected and -uninfected adults during the pre-PCV era and provide a robust baseline to calculate the indirect effect of PCV in future studies.

Invasive Disease Caused Simultaneously by Dual Serotypes of Streptococcus pneumoniae

“…The most common serotypes identified among patients with dual infection were PCV13 serotypes 1, 6A, 6B, 14, 19A, and 19F. This is in line with the overall IPD serotype prevalence prior to routine use of PCV13 in South Africa (25)(26)(27) during the period in which the majority of these cases occurred, where more than 80% of IPD cases were due to PCV13 serotypes (27). It is interesting, however, that the majority of coinfecting serotypes (6A, 6B, and 19F) identified in our study are known to have low invasive disease potential (28).…”

Both the inflammatory response and clinical outcome differ markedly between adults with pneumococcal and meningococcal meningitis in a high HIV-1 prevalent setting in sub-Saharan Africa

“…Most of our patients were HIV-1 co-infected, interestingly neither outcome nor CSF WCC differed between those with or without HIV co-infection. HIV is a wellrecognised risk factor for acquisition of both PM and MM [35,36]. However, HIV appears to have little impact on the established inflammatory response in either infection, although the proportion of HIV-negative patients was relatively small.…”

Pneumococcal Bacteremia Complicated by Hemophagocytic Lymphohistiocytosis

“…Immunodeficiency does not obviate a thorough workup; in fact, a localized source may be more readily identified in HIV infected patients with pneumococcal bacteremia compared to the HIV uninfected. 11 Pneumonia is the predominant cause of pneumococcal blood stream infections; sinusitis and otitis media account for only 4% of cases. 12 In nearly a fifth of cases of Streptococcal bacteremia, no clear source is identified.…”