Equines as reservoirs of human fascioliasis: transmission capacity, epidemiology and pathogenicity in Fasciola hepatica-infected mules.

The research article investigates the role of mules in the transmission, epidemiology, and pathogenicity of Fasciola hepatica, a liver fluke causing fascioliasis, a zoonotic disease. The study draws attention to mules, a topic that has been given little consideration in prior research, despite the prevalence being 39.5% in the Aconcagua region and 24.4% in Uspallata, Argentina.

Research Methodology

• The study involved a sample of 208 mules from the high-altitude regions of Mendoza province, Argentina. The prevalence of Fasciola hepatica was 39.5% in 81 mules from Aconcagua, and 24.4% in 127 from Uspallata.
• Lymnaeids, freshwater snails that serve as the intermediate host for liver flukes, were likewise studied. The ones from Uspallata revealed ribosomal DNA internal transcribed spacer (ITS) markers ITS-1 and ITS-2 combined haplotype 3C of Galba truncatula.
• This study estimated a mean egg volume of 101,242 eggs/mule/day.

Findings on Transmission

• The lymnaeids were found to be susceptible to infection by egg miracidia from mules, which means mules can help sustain the Fasciola hepatica cycle on their own.
• The research reveals an enhanced Fasciola hepatica/Galba truncatula transmission pattern at high altitude, proving the likelihood of mules as significant players in the disease’s spread.

Pathogenicity and Impact on Mules

• Mule infection susceptibility lies intermediate between horses and donkeys, but it leans more toward the latter.
• Individual burdens were found to range from 20 to 97 flukes per mule.
• Massive infection may cause death in mules, as revealed by anatomopathology and histopathology.
• Fasciola hepatica infection in mules results not just in anemia but also causes severe immunosuppression, as evidenced by the decline in red blood cells, hemoglobin, leucocytes and lymphocytes.
• It also appears to affect liver functions as demonstrated by the elevated biochemical marker values.

Implications on Human Fascioliasis Spread

• Historically, mules might have played a role in the past exchanges with Chile and Bolivia through Mendoza province, leading to fascioliasis spread. This is confirmed by the proven susceptibility of mules to Fasciola hepatica and their potential to maintain the disease life cycle.
• Therefore, mules could contribute to the transmission of both Fasciola hepatica and Galba truncatula to human fascioliasis-endemic areas in these countries.