Persisting High Prevalence of Pneumococcal Carriage among HIV-Infected Adults Receiving Antiretroviral Therapy in Malawi

HIV-infected adults have high rates of pneumococcal carriage and invasive disease. We investigated the effect of antiretroviral therapy (ART) on pneumococcal carriage in HIV-infected adults prior to infant pneumococcal conjugate vaccine (PCV) rollout.

We recruited HIV-infected adults newly attending a rural HIV clinic in northern Malawi between 2008 and 2010. Nasopharyngeal samples were taken at baseline and after 6, 12, 18 and 24 months. We compared pneumococcal carriage by ART status using generalized estimated equation models adjusted for CD4⁺ cell count, sex, seasonality, and other potential confounders.

In total, 336 individuals were included, of which 223 individuals started ART during follow-up. Individuals receiving ART had higher pneumococcal carriage than individuals not receiving ART (25.9 vs. 19.8%, P = 0.03) particularly for serotypes not included in PCV13 (16.1 vs. 9.6% P = 0.003). Following adjustment, increased carriage of non-PCV13 serotypes was still observed for individuals on ART, but results for all serotypes were nonsignificant.

Pneumococcal carriage in HIV-infected adults in Malawi remained high despite use of ART, consistent with failure of mucosal immune reconstitution in the upper respiratory tract. There was evidence of increased carriage of non-PCV13 serotypes. HIV-infected adults on ART could remain an important reservoir for pneumococcal diversity post infant pneumococcal vaccine introduction. Control of pneumococcal disease in African HIV remains a priority.

Below:  Pneumococcal colonization and median CD4+ cell count on baseline and by month since ART/month since baseline in patients receiving ART or not

Below:  Carriage of serotypes by ART status.

(a) Serotypes included in PCV13. (b) Serotypes not included in PCV13. ∗Factor typing not done, ∗∗Not able to establish factor typing. ART, antiretroviral therapy; PCV, pneumococcal conjugate vaccine.

Below: Seasonality of pneumococcal carriage.

(a) Crude carriage prevalence; (b) Fitted parametric spline from adjusted generalized estimated equations model. Grey area represents 95% confidence intervals. Black horizontal bars represent months in the rainy season (December–April).

Full article at: http://goo.gl/dOIO3d

By: Ellen Heinsbroek,a Terence Tafatatha,b Amos Phiri,b Bagrey Ngwira,b,c Amelia C. Crampin,b,d Jonathan M. Read,e andNeil Frencha

aDepartment of Clinical Infection, Microbiology, Institute of Infection and Global Health, University of Liverpool, UK

bKaronga Prevention Study, Chilumba

cThe Polytechnic, University of Malawi, Blantyre, Malawi

dDepartment of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London

eDepartment of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, UK. 

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