People infected with helminths who are treated with albendazole but remain infected experience changes in their microbiome, notably a significant alteration in Bacteroidetes, according to study results published in PLOS Neglected Tropical Diseases.
“In our study, we used multivariate analysis, which takes into account the microbiome data structure and [characterizes] the microbiome composition in relation to helminth infection and treatment,” Ivonne Martin, MSc, a PhD candidate at Leiden University Medical Center in the Netherlands, told Infectious Disease News. “As a result of the analyses and the study design, we report that neither helminth infection nor treatment separately change the microbiome composition. Notably, in subjects who were initially helminth-infected and remained infected after treatment, the microbiome composition of those who received albendazole was significantly different [from] those in the placebo group.”
Martin and colleagues conducted a double-blind placebo-controlled trial in Nangapanda, Indonesia, an endemic area for soil-transmitted helminths. They randomly assigned 150 participants to placebo (n = 81; mean age, 27.85 years; 55.6% female) or 400 mg albendazole (n= 69; mean age, 27.38 years; 56.5% female) at 3 months after baseline and repeated every 3 months for seven treatment rounds, with treatment completed at 21 months. Infection with helminths was measured before treatment and at 21 months after first treatment using DNA isolated from fresh stool samples. A cross-sectional analysis was conducted at pretreatment to measure the effect of infection and at post-treatment to determine the effect of the infection and treatment on microbiome composition.
Ninety-four of the 150 participants were infected with one or more helminth species at baseline, with hookworm being the most prevalent species (52.1%).
No differences were seen between the cohort at a phylum level at pretreatment in terms of abundance between helminth-infected and -uninfected individuals.
The prevalence of soil-transmitted helminth infection was 21.7% in the participants treated with albendazole and 54.3% in the participants in the placebo cohort (P < .001) after 21 months of treatment. The researchers reported that there were no overall microbiome differences between the two cohorts at the end of treatment. However, for the participants who remained infected with helminths after treatment, microbiome composition was significantly different than in the participants who received albendazole and those receiving placebo. The difference was primarily attributed to Bacteroidetes.
Albendazole was most effective in treating hookworm (infection rate of 24.7% in placebo vs. 4.3% for albendazole) and Ascaris lumbricoides (28.4%, placebo vs. 4.3%, albendazole). The researchers noted that it was not as effective against Trichuris trichiura, and participants who remained infected had a helminth composition dominated by T. trichiura.
They also noted that 12 participants (two from the albendazole cohort and 10 from the placebo cohort) who were uninfected at baseline developed helminth infection during the study.
“Overall, there is no simple relationship between helminths and the microbiome; this is only apparent when an anthelmintic drug is given,” Martin said. “This result suggests that an anthelminthic drug can affect the cross-talk between helminths and microbiome, i.e., that there may be a mechanism by which helminths ensure their own survival when exposed to anthelminthic treatment by altering their host’s intestinal microbiome composition. It is thus beneficial to repeat this study to analyze the mechanisms that are involved; for example, is it possible that the metabolites from a helminth exposed to albendazole change the bacterial composition of the host?” – by Bruce Thiel
The researchers report no relevant financial disclosures.