Understanding the widespread use of veterinary ivermectin for Chagas disease, underlying factors and implications for the COVID-19 pandemic: a convergent mixed-methods study

Abstract

Objectives: Veterinary ivermectin (vet-IVM) has been used widely in Latin America against COVID-19, despite the lack of scientific evidence and potential risks. Widespread vet-IVM intake was also discovered against Chagas disease during a study in Bolivia prior to the pandemic. All vet-IVM-related data were extracted to understand this phenomenon, its extent and underlying factors and to discuss potential implications for the current pandemic.

Design: A convergent mixed-methods study design including a survey, qualitative in-depth interviews (IDI) and focus group discussions (FGD).

Setting: A cross-sectional study conducted in 2018 covering the geographic area of Monteagudo, an endemic municipality for Chagas disease.

Participants: A total of 669 adult household representatives from 26 communities participated in the survey, supplemented by 14 IDI and 2 FGD among patients, relatives and key informants.

Results: 9 IDI and 2 FGD contained narratives on vet-IVM use against Chagas disease. Five main themes emerged: (1) the extent of the vet-IVM phenomenon, (2) the perception of vet-IVM as a treatment for Chagas disease, (3) the vet-IVM market and the controversial role of stakeholders, (4) concerns about potential adverse events and (5) underlying factors of vet-IVM use against Chagas disease.In quantitative analysis, 28% of participants seropositive for Chagas disease had taken vet-IVM. Factors associated with multivariate analysis were advanced age (OR 17.01, 95 CI 1.24 to 36.55, p=0.027 for age above 60 years), the experience of someone close as information source (OR 3.13, 95 CI 1.62 to 5.02, p<0.001), seropositivity for Chagas disease (OR 3.89, 95 CI 1.39 to 6.20, p=0.005) and citing the unavailability of benznidazole as perceived healthcare barrier (OR 2.3, 95 CI 1.45 to 5.18, p=0.002). Participants with an academic education were less likely to report vet-IVM intake (OR 0.12, 95 CI 0.01 to 0.78, p=0.029).

Conclusions: Social determinants of health, the unavailability of treatment and a wonder drug image might contribute to the phenomenon of vet-IVM.

Keywords: COVID-19; infection control; public health; tropical medicine.

Figure 1

Mixed-methods convergent design using parallel data collection with an iterative approach. vet-IVM, veterinary ivermectin. * To further explore the theme on vet- IVM a veterinarian was purposefully sampled.Vet- IVM was not brought up purposefully in other qualitative interviews in order to assess its relevance compared to other treatments.

Figure 2

Bivariate analysis on factors associated with veterinary ivermectin intake, test for trend. Variable categories: education 0=no/incomplete schooling, 1=complete schooling (secondary), 2=tertiary education, 3=academic. Health status and emotional health status 1=very good, 2=good, 3=fair, 4=bad, 5=very bad. Perceived effectiveness of health system: responses to the question “If I go to the health center, I will get all the help I need to get cured”. Belief in adverse events of benznidazole (BNZ): responses to the question: ‘The treatment has strong negative effects’, both assessed on a 5-point Likert scale 1=strongly disagree, 2=disagree, 3=uncertain, 4=agree, 5=strongly agree. ns, p>0.05; *0.01