Water, Sanitation and Hygiene Access, Insecurity, Inequalities, Including Menstrual Health, and Their Association With Abscess Incidence Among People Who Inject Drugs in the Tijuana and San Diego Metropolitan Area

Background: Access to water, sanitation and hygiene (WASH) are human rights often violated among marginalized populations. WASH is also a major dimension required for menstrual health (MH). People who inject drugs (PWID) have particular water needs, such as for preparing drugs for injection and for cleaning wounds. Insecurity accessing WASH services is associated with infectious-related diseases, including abscesses. Little research has explored WASH, MH, and WASH-related health conditions among PWID, especially on the United States (US) – Mexico border. The objective of this research was to provide the first comprehensive assessment of WASH access, insecurity and inequalities, including MH, among PWID in the Tijuana – San Diego metropolitan area and its association with abscess incidence.

Methods: This dissertation included cross-sectional and longitudinal analyses using existing data from the binational cohort study La Frontera among PWID in the Tijuana – San Diego metropolitan area in 2020-2023. The first chapter is a descriptive analysis of WASH access, insecurity and inequalities (N=586). The second chapter includes the development and validation of a scale to measure the WASH dimension of MH among PWID who menstruate (N=125). Thirdly,s through a longitudinal analysis, WASH insecurity variables are examined as predictors of abscess incidence in a 24-month follow up period in 2020-2023 (N=647). 

Results: Basic access to drinking water, hand hygiene, sanitation and bathing were low (89%, 38% and 28% respectively) and open defecation was common (38%). WASH insecurity variables were higher among participants experiencing unsheltered homelessness. Among PWID who menstruate, our brief ‘WASH Domain Scale-12’ was found to be reliable and valid. Over 24 months of follow-up, the incidence of abscesses was high (24 per 100 person-years). After adjusting for covariates, the hazard of developing an abscess was independently associated with the use of non-improved water sources for preparing drugs, bathing insecurity and open defecation.

Conclusions: The three chapters presented here highlight low levels of WASH access among vulnerable PWID living on the US-Mexico border, and describe critical implications for health inequalities, including for MH and infectious disease risk. Accessible WASH infrastructure should be systematically ensured among PWID communities and championed as a key component of harm reduction.