Metabolic and behavioral effects of PHMB on Biomphalaria glabrata: a strategy for schistosomiasis control

The snail Biomphalaria glabrata is an important transmitter of Schistosoma mansoni, the parasite that causes schistosomiasis. One of the strategies for controlling the disease involves interrupting the transmission cycle of the parasite by managing the host snail population. In a previous study, the sanitizer polyhexamethylene biguanide hydrochloride (PHMB) caused mortality in B. glabrata starting at 1.6 mg L-1. The present study evaluated the activity of PHMB at concentrations of 0.4, 0.6, and 0.8 mg L-1 through behavioral changes and biochemical biomarkers. The snails were evaluated every 24 hours for behavioral changes such as lethargy, mucus secretion, shell confinement, exposure of the cephalopodal mass, and lack of movement. After 96 hours, hemolymph was collected via cardiac puncture for analysis of glucose, total protein, urea, uric acid, creatinine, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes, and organic acids involved in the glycolytic pathway, tricarboxylic acid cycle, and lipid and protein metabolism. The exposure of the cephalopodal mass with lack of movement showed the highest rates of behavioral changes, ranging from 72% to 95%. Additionally, exposure to PHMB resulted in the use of fatty acids and proteins as energy substrates. Our results suggest a continuation of studies on energy metabolism pathways as a promising target for controlling snail vectors of parasites that cause neglected diseases such as schistosomiasis.