Abstract
BackgroundEnteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods.MethodsWe collected bed and living room dust samples from households of children participating in a clinical trial of anthelmintic treatment in rural coastal Ecuador. Dust was examined for presence of DNA specific for 11 enteric parasites (Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Toxocara canis and T. cati, Giardia lamblia, Blastocystis hominis, Cryptosporidium spp., and Entamoeba histolytica) by quantitative PCR (qPCR).ResultsOf the 38 households sampled, 37 had positive dust for at least one parasite and up to 8 parasites were detected in single samples. Positivity was greatest for B. hominis (79% of household samples) indicating a high level of environmental fecal contamination. Dust positivity rates for individual pathogens were: S. stercoralis (52%), A. lumbricoides (39%), G. lamblia (39%), Toxocara spp. (42%), hookworm (18%) and T. trichiura (8%). DNA for Cryptosporidium spp. and E. histolytica was not detected. Bed dust was more frequently positive than floor samples for all parasites detected. Positivity for A. lumbricoides DNA in bed (adjusted OR: 10.0, 95% CI: 2.0–50.1) but not floor dust (adjusted OR: 3.6, 95% CI: 0.3–37.9) was significantly associated with active infections in children.ConclusionsTo our knowledge, this is the first use of qPCR on environmental samples to detect a wide range of enteric pathogen DNA. Our results indicate widespread contamination of households with parasite DNA and raise the possibility that beds, under conditions of overcrowding in a humid tropical setting, may be a source of transmission.
Highlights
Enteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods
Positivity rates by PCR for dust samples were greatest for B. hominis (59/75, 79% samples; 37/38, 97% households), followed by S. stercoralis (52% samples; 74% households), A. lumbricoides (39%; 63%), G. lamblia (24%; 39%), Toxocara spp. [T. canis (23%; 39%); T. cati (4%; 8%); any Toxocara (24%; 42%)], hookworm [A. duodenale (9%; 18%); N. americanus (1%; 3%); any hookworm (9%; 18%)] and T. trichiura (4%; 8%)
Rates of positivity in floor versus mattress dust are shown in Fig. 1a: trends of greater rates were observed for all parasites in mattress samples and only mattress samples were positive for hookworms and T. trichiura
Summary
Enteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods. Parasite transmission is considered to occur through contacts with contaminated soil, food and drinking water. Mejia et al Parasites Vectors (2020) 13:141 washing after defecation, cleaning of foods, and avoidance of wastewater) [2,3,4] is considered sufficient to prevent transmission of these infections, studies systematically implementing such strategies (e.g. WASH) have had mixed success [5]. Previous studies have sampled for presence of infectious parasite stages as sources of transmission around households including latrines [6, 7] and within houses [8,9,10] but none to our knowledge have used sensitive molecular methods to detect specific parasite DNA
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