Effect of ART on malaria parasitaemia and clinical episodes in adults in rural Uganda: A population-based cohort study Billy N. Mayanja 1, Kathy Baisley 2, Natasha Larke 2, Patrick Kazooba 1, Ben Masiira 1, Peter Hughes 1, Lieve Van der Paal 3, Dermot Maher 1, Heiner Grosskurth 1,2, Pontiano Kaleebu 1,2 1. MRC/UVRI Uganda Research Unit on AIDS, Entebbe, Uganda 2. London School of Hygiene & Tropical Medicine, London, UK 3. International Rescue Committee, Dar es Salam, Tanzania

Background: HIV and malaria Incidence of clinical malaria and parasitaemia increased in advanced HIV disease P. falciparum associated with higher HIV viral loads Cotrimoxazole prophylaxis reduces risk of OIs, but also has known anti-malarial effect

Background Hypothesis Immune restoration due to ART should reduce effects of HIV on malaria Objective To examine the effect of ART on - malaria parasitaemia - clinical malaria (parasitaemia and ≥ C)

Methods: study population 1990: HIV clinical cohort established in rural southwest Uganda Participants reviewed 3-monthly and when sick 2004: ART and CTX prophylaxis introduced : free insectide treated nets (ITNs) issued (targeting women and children <5 yrs)

Methods: Laboratory Full blood counts and CD4 cell counts: at 3-monthly routine visits Malaria microscopy: routinely and at fever episodes

Methods: data analysis Participants categorised as: -HIV negative, -HIV positive not yet on ART -HIV positive on ART HIV positive participants who later started ART contributed to 2 categories Assumed no risk within a 28-days after last episode Malaria incidence compared between study categories (random effects Poisson regression)

Results: Characteristics at study entry (1) CharacteristicHIV status at entry to study 1 P-value Negative (228) N (%) HIV-positive not on ART 2 (327) N (%) HIV-positive on ART (197) N (%) Sex Women115 (50)185 (57)135 (69)0.001 Age (years) < Median [IQR] 16 (7) 61 (27) 69 (30) 82 (36) 38 [32-50] 56 (17) 121 (37) 89 (27) 61 (19) 33 [27-41] 24 (12) 58 (30) 63 (33) 49 (25) 37[30-45] < Study entry defined as 1 st January, 2004 or date of enrolment in the clinical cohort, whichever was later HIV positive initially not on ART eventually started ART during follow-up

Characteristics at study entry (2) CharacteristicsHIV status at entry to study 1 P-value Negative (228) N (%) HIV-positive not on ART (327) N (%) HIV-positive on ART (197) N (%) Marital status Single Married Div/Wid/Sep 29 (13) 165 (72) 34 (15) 26 (8) 208 (64) 89 (28) 17 (9) 88 (45) 90 (46) <0.001 Ethnicity Baganda Banyarwanda Others 166 (74) 38 (17) 22 (10) 199 (61) 79 (24) 49 (15) 126 (65) 44 (23) 25 (13) 0.05 CD4 count < – – (21) 37 (12) 61 (20) 142 (47) 140 (78) 25 (14) 9 (5) 7 (4) <0.001

Summary of follow-up participants enrolled into study -524 (70%) HIV-infected -336 (64%) of these on ART (197 at entry, 139 later) 2855 person years of observation 974 clinical malaria episodes:  incidence of 33.2/100 pyrs (95% CI: ) 1787 malaria parasitaemia episodes:  incidence of 61.9/100 pyrs (95% CI: )

Incidence of clinical malaria by HIV and ART status;

Clinical malaria episodes by HIV and ART status 2004 – 2010 CharacteristicsHIV-negativeHIV-positive not on ART HIV-positive on ART Episodes/visits Patients with: Any episode >1 episode 184/6111 (3%) 80/228 (35%) 47/228 (21%) 305/5107 (6%) 131/327 (40%) 71/327 (22%) 485/9549 (5%) 147/336 (44%) 96/336 (29%) Parasite counts < N= (68%) 29 (16%) 12 (7%) 11 (6%) 2 (1%) 4 (2%) N= (45%) 47 (15%) 33 (11%) 35 (11%) 21 (7%) 33 (11%) N= (42%) 92 (19%) 56 (12%) 59 (12%) 25 (5%) 45 (9%) Species P falciparum 100%94%97%

Incidence of clinical malaria after introduction of ITNs HIV study categoryIncidence rate/100pyr Adjusted 1 rate ratio (95% CI) P-value HIV negative Pre introduction ITN 1 st year after ITN >1 year after ITN ( ) 0.31 ( ) <0.001 HIV positive not on ART Pre introduction ITN 1 st year after ITN >1 year after ITN ( ) 0.23 ( ) <0.001 HIV positive on ART Pre introduction ITN 1 st year after ITN >1 year after ITN ( ) 0.18 ( ) < Adjusted for age, sex and visit type

Risk factors for clinical malaria CharacteristicsIncidence rate/100pyr Adjusted 1 rate ratio (95% CI) P-value HIV and ART status HIV-negative HIV positive no ART HIV positive ART <2yrs HIV positive ART 2+yr ( ) 1.89 ( ) 1.31 ( ) <0.001 Current age (years) < – – – ( ) 0.55 ( ) 0.48 ( ) 0.56 ( ) <0.001 Sex Male Female ( ) Adjusted for HIV and ART status, age, sex, introduction of ITN and visit type

Risk factors for clinical malaria CharacteristicsRate/100pyAdjusted 1 rate ratio (95% CI) P-value CD4 count (cells/mm 3 ) < ( ) 2.07 ( ) 3.03 ( ) < Adjusted for HIV serostatus, age, sex and visit type

Summary and discussion (1) Incidence of clinical malaria & malaria parasitaemia: was high in this area of Uganda for parasitaemia ~ 2-fold than that of clinical malaria decreased over time in all groups higher in HIV+ve not on ART (vs. HIV-ve) higher in HIV+ve on ART < 2 years (vs. HIV-ve) higher in HIV+ve on ART > 2 years (vs. HIV-ve) increased with HIV disease progression decreased with increasing age regardless of HIV and ART status

Summary and discussion (2) Very high malaria incidence in people initiating ART at start of programme (2004/05)  due to advanced immuno-suppression ? ART associated with steep reduction of malaria incidence Decline likely to be also due to CTX prophylaxis (+ ITN)  would explain reduction of malaria incidence - in non-ART group and - excess reduction among those on ART > 2 years Decline in malaria incidence among HIV-ve  due to introduction of ITNs

Summary and discussion (3) Strengths Prospective cohort with regular follow up visits Weaknesses could not examine independent effects of ITN use and cotrimoxazole prophylaxis

Conclusion ART introduction associated with steep reduction of malaria incidence in HIV+ve, likely due to improved immune function Probably in part confounded by introduction of CTX prophylaxis (in HIV+ve) and ITNs (in general population) Observations support the combination of all three interventions in areas with high prevalence of HIV infection and malaria

Acknowledgements Study participants Clinic, laboratory and statistics staff Medical Research Council (UK) for funding the study