The impact of HIV infection on the burden and severity of influenza illness in Malawian adults

Ho, A ORCID: 0000-0003-1465-3785, Aston, S, Jary, H, Alaerts, M, Menyere, M, Mallewa, J, Nyirenda, M, Everett, D, French, N ORCID: 0000-0003-4814-8293 and Heyderman, R
(2016) The impact of HIV infection on the burden and severity of influenza illness in Malawian adults. PhD thesis, University of Liverpool.

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Background. Influenza infection and its complications cause substantial morbidity and mortality worldwide. However, the epidemiology of influenza in sub-Saharan Africa (SSA) is not well known. Furthermore, the effects of HIV infection on influenza burden and severity in adults in a region with high HIV prevalence are also poorly characterised. Although seasonal influenza vaccination is recommended for HIV-infected persons in developed settings, it is not part of routine HIV care in Africa. The primary aim of this thesis was to examine the impact of HIV on the incidence and severity of influenza infection among adults in urban Malawi, to determine whether HIV-infected adults should be prioritised for influenza preventative measures. Methods. At the Queen Elizabeth Central Hospital in Blantyre, Malawi, we characterised the epidemiology, seasonality and risk factors for influenza infection in Malawian adults enrolled in a sentinel surveillance study. Secondly, we established a prospective cohort to compare the incidence of laboratory-confirmed influenza illness between HIV-infected and HIV-uninfected adults over two years. Thirdly, we conducted a case control study of adults with mild (influenza-like illness (ILI)) and severe (hospitalised lower respiratory tract infection (LRTI)) influenza illness to explore risk factors for severe influenza presentation, with HIV as the primary exposure of interest. Lastly, as a potential mechanism through which influenza and other respiratory viral infections predispose to secondary bacterial pneumonia, we investigated the association between respiratory viral infections and nasopharyngeal carriage density of Streptococcus pneumoniae in a cross-sectional and case control analysis nested within the prospective cohort. Results. Influenza was a common cause of mild and severe acute respiratory infections in Malawian adults in the hospital-based sentinel surveillance. Pregnant women were found to have nearly double the risk of hospital-attended influenza infection compared to non-gravid women of childbearing age. In the prospective cohort of 608 adults (59% HIV-reactive), 24/229 (10.5%) ILI episodes in HIV-infected and 5/119 (4.2%) in HIV-uninfected adults were influenza PCR-positive (incidence rates 46.0 vs. 14.5 per 1000 person years). After accounting for potential confounders, HIV-infected adults had an approximately three times higher incidence of influenza infection compared to HIV-uninfected adults. In the case control study, HIV was the single most important risk factor for severe influenza-related presentation; HIV-infected adults experienced a five-fold greater risk of severe influenza disease compared to HIV-uninfected adults, and over 50% of influenza-related hospitalised LRTI were attributable to HIV. Influenza infection was associated with pneumococcal carriage, but respiratory viral infection was not associated with pneumococcal acquisition or an increase in pneumococcal colonisation density. Conclusion. We have clearly demonstrated a high burden of influenza disease among Malawian adults. Moreover, HIV-infected adults have increased susceptibility and severity of influenza presentations, thus should be considered a priority group for targeted vaccination in the region. Influenza vaccine policies that maximise health benefit through efficient use of limited resources are urgently needed.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Influenza, HIV, Malawi
Divisions: Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 09 Jan 2017 11:45
Last Modified: 16 Dec 2022 16:19
DOI: 10.17638/03000556
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