Diversity and Prevalence of Helminths and Protozoa Among Pregnant Women in Tropical Ecuador: Implications for Chemotherapy.

Deworming for pregnant women using a single dose of albendazole or mebendazole is recommended by the WHO in areas where the baseline prevalence of hookworm and/or trichuriasis is >20%. However, other helminths and protozoa infecting pregnant women are not affected by these drugs and dosages. To assess the prevalence and diversity of intestinal helminth and protozoan infections, we analyzed stool samples from pregnant women recently enrolled into a birth cohort, along a rural-urban gradient in northern coastal Ecuador from 2019 to 2022. Participants provided a stool sample in their third trimester (n = 444). Samples were concentrated by the Ritchie method and observed microscopically for the detection of cysts, eggs, and larvae. The overall prevalence of infection with one or more parasites was 69% (95% CI: 67-74%), ranging from 52% in urban participants to 76% in rural participants (percentile rank = 1.39, 95% CI: 1.07-1.87). This differential between urban and rural communities persisted when data were disaggregated into helminth and protozoan infections (prevalence = 19% and 46%, respectively, in urban participants compared with 42% and 58% among rural participants). The most prevalent helminth was Ascaris lumbricoides (27%), followed by Trichuris trichiura (13%) and hookworm (7.4%). Hymenolepis nana, Strongyloides stercoralis, and Enterobius vermicularis were also observed. Six protozoan pathogens were detected, including Entamoeba histolytica/dispar (23%), Giardia intestinalis (5%), and Balantidium coli, along with nine protozoa that are nonpathogenic or of debated pathogenicity. The high infection burden and diversity of intestinal parasites found in this study highlight a need to revise strategies for preventing and treating intestinal parasitic infections in pregnant women.