Epidemiology of Strongyloides stercoralis infection in Bolivian patients at high risk of complications.

Background Strongyloidiasis can be fatal in immunocompromised patients, but few epidemiological studies investigated the burden of this neglected tropical disease among these populations, particularly in low- and middle-income countries such as Bolivia. This study aimed to fill in this gap by estimating prevalence rate and risk factors associated with strongyloidiasis among patients at high risk of complications Methods A cross-sectional study was carried out in Santa Cruz (elevation 400 meters, tropical climate) and Cochabamba (elevation 2,500 meters, temperate climate), among patients with cancer, HIV infection and rheumatic or hematologic disease, using four coproparasitological techniques and one serological (ELISA) test. Results In total, 1,151 patients participated in this study, including individuals who were HIV-positive (30%) or with rheumatic (29%), oncologic (32%) or hematologic (9%) diseases. The serological and coproparasitological prevalence was 23.0% (95% confidence interval [CI], 20.7-25.5; n = 265/1151) and 7.6% (95% CI, 6.2-9.3; n = 88/1151), respectively, with an estimated actual prevalence of 20.2% (95% CI, 17.9-22.5). Positive serology and positive coproparasitology were associated with younger age and lower education levels. There was no significant difference in prevalence between Cochabamba and Santa Cruz as defined by coproparasitology (6.4% vs. 8.9%; p = 0.11) or serology (24.0% vs. 22.0%; p = 0.4). Among 64 patients in Cochabamba who had never travelled to the tropical lowlands, 5 (7.8%) had a positive coproparasitology. Conclusions Strongyloidiasis is widely prevalent in Bolivia among vulnerable patients at increased risk of life-threatening complications. Transmission of the parasite occurs both in tropical lowlands and temperate elevation ( 2,500 m). Control strategies to prevent transmission and complications of this serious parasitic disease should be urgently reinforced. Author summary Strongyloidiasis is an understudied chronic intestinal infection and one of the most overlooked of the neglected tropical diseases, particularly in countries such as Bolivia. The strongyloidiasis usually remains paucisymptomatic for decades in immunocompetent persons, but may lead to severe conditions with high mortality rates in immunocompromised individuals. We carried out a study to explore the epidemiology of strongyloidiasis among Bolivian patients with cancer, HIV infection, and rheumatic or hematologic diseases. Our study highlighted that strongyloidiasis was widely prevalent in tropical and inter-Andean temperate areas of Bolivia among patients at high risk of life-threatening complications. One in five participants was infected. We showed that strongyloidiasis was highly prevalent in both tropical and temperate regions. Improved access to adequate diagnosis, treatment, and preventive measures are therefore urgently required in Bolivia, and most likely elsewhere in the region. Treatment of uncomplicated strongyloidiasis is simple, highly effective, and potentially life-saving.