Household costs associated with zoonotic Plasmodium knowlesi, P. falciparum, P. vivax and P. malariae infections in Sabah, Malaysia.

Background: Malaysia has free universal access to malaria care; however, out-of-pocket costs are unknown. This study estimated and compared household costs of illness during a unique time when four species of malaria were present, due to the emergence of zoonotic Plasmodium knowlesi during the elimination phase of non-zoonotic species in Sabah, Malaysia.

Methodology/principal findings: Household costs were estimated from patient-level surveys collected from four hospitals between 2013 and 2016. Direct costs including medical and associated travel costs, and indirect costs due to lost productivity were included. One hundred and fifty-two malaria cases were enrolled: P. knowlesi (n=108), P. vivax (n=22), P. falciparum (n=16), and P. malariae (n=6). Costs were inflated to 2023 Malaysian Ringgits and reported in United States dollars (US$). Across all cases, the mean total costs were US$131 (SD=102), with productivity losses accounting for 58% of costs (US$76; SD=70). P. vivax had the highest mean total household cost at US$199 (SD=174), followed by P. knowlesi and P. falciparum at US$119 (SD=81 and SD=83, respectively), and P. malariae (US$99; SD=42). Most patients (80%) experienced direct health costs above 10% of monthly income, with 58 (38%) patients experiencing health spending over 25% of monthly income, consistent with catastrophic health expenditure.

Conclusions/significance: Despite Malaysia's free health-system care for malaria, patients and families face other related medical, travel, and indirect costs. Household out-of-pocket costs were driven by productivity losses; primarily attributed to infections in working-aged males in rural agricultural-based occupations. Costs for P. vivax were higher than those of P. knowlesi and P. falciparum. This may be attributable to a younger age profile and the longer treatment required to clear the liver-stage parasites of P. vivax.