Severe Influenza-associated Respiratory Infection in High HIV Prevalence Setting, South Africa, 2009–2011

Cheryl Cohen

, Jocelyn Moyes, Stefano Tempia, Michelle Groom, Sibongile Walaza, Marthi Pretorius, Halima Dawood, Meera Chhagan, Summaya Haffejee, Ebrahim Variava, Kathleen Kahn, Akhona Tshangela, Anne von Gottberg, Nicole Wolter, Adam L. Cohen, Babatyi Kgokong, Marietjie Venter, and Shabir A. Madhi

Author affiliations: National Health Laboratory Service, Johannesburg, South Africa (C. Cohen, J. Moyes, S. Walaza, M. Pretorius, A. Tshangela, A. von Gottberg, N. Wolter, B. Kgokong, M. Venter, S.A. Madhi); University of the Witwatersrand, Johannesburg (C. Cohen, J. Moyes, M. Groom, E. Variava, K. Kahn, A. von Gottberg, N. Wolter, S. A. Madhi); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (S. Tempia, A.L. Cohen); Centers for Disease Control and Prevention–South Africa, Pretoria, South Africa (S. Tempia, A. L. Cohen); University of KwaZulu-Natal, Durban, South Africa (H. Dawood, M. Chhagan, S. Haffejee); Pietermaritzburg Metropolitan Hospital, Pietermaritzburg, South Africa (H. Dawood); Klerksdorp Tshepong Hospital, Klerksdorp, South Africa (E. Variava); Umeå University, Umeå, Sweden (K. Kahn); INDEPTH Network, Accra, Ghana (K. Kahn); University of Pretoria, Pretoria (M. Venter)

Abstract

Data on influenza epidemiology in HIV-infected persons are limited, particularly for sub-Saharan Africa, where HIV infection is widespread. We tested respiratory and blood samples from patients with acute lower respiratory tract infections hospitalized in South Africa during 2009–2011 for viral and pneumococcal infections. Influenza was identified in 9% (1,056/11,925) of patients enrolled; among influenza case-patients, 358 (44%) of the 819 who were tested were infected with HIV. Influenza-associated acute lower respiratory tract infection incidence was 4–8 times greater for HIV-infected (186–228/100,000) than for HIV-uninfected persons (26–54/100,000). Furthermore, multivariable analysis showed HIV-infected patients were more likely to have pneumococcal co-infection; to be infected with influenza type B compared with type A; to be hospitalized for 2–7 days or > 7 days; and to die from their illness. These findings indicate that HIV-infected persons are at greater risk for severe illnesses related to influenza and thus should be prioritized for influenza vaccination.

Knowledge is limited about influenza virus–associated illness and death in persons infected with HIV type 1, particularly in sub-Saharan Africa (1,2). In 2009, South Africa had ≈5 million HIV-infected persons, and HIV prevalence among pregnant women was 29% (3,4). Influenza virus circulates seasonally in South Africa, during the Southern Hemisphere winter (5).
Studies from the United States suggest that, in the absence of highly active antiretroviral therapy (HAART), HIV-infected adults have an increased risk of seasonal influenza hospitalization (1), death (6), and prolonged illness compared with the general population. This risk decreased following the widespread introduction of HAART (6,7). In 2011, ≈52% of eligible HIV-infected adults in South Africa were receiving HAART (8), and HAART-naive HIV-infected children had an 8-fold greater risk for influenza-associated pneumonia hospitalization and a trend toward a higher case-fatality rate (CFR) (8% vs. 2% in HIV-uninfected children) (2,9). Adults in South Africa with AIDS had similar influenza-associated death rates to those for adults in the United States with AIDS in the pre-HAART era (6). In Kenya, HIV-infected adults were at increased risk for influenza-associated pneumonia hospitalization compared with HIV-uninfected adults (10,11).