Albendazole resistance in Fasciola hepatica: surveillance in different areas of Spain and Argentine

Abstract

Triclabendazole is the worldwide most used compound to control Fasciola hepatica and reports on drug resistance are abundant. Although the flukicidal use of albendazole (ABZ) is not as widespread, ABZ-resistance reports in liver flukes have increased in recent years. The work reported here describes a survey of the susceptibility/resistant status of different F. hepatica isolates to ABZ in two geographic regions of Spain and Argentine, using the egg hatch test (EHT). F. hepatica eggs were obtained from the gall bladder or faeces of natural infected cattle or sheep from different geographical areas of northern Spain (Castilla y León, Galicia and Asturias) and east (Litoral) and south (Patagonia) of Argentine. Fluke eggs were incubated at 25 ºC in darkness for a 12 h period with ABZ (0.5 nmol/mL). Untreated eggs served as control. After incubation, all eggs were gently washed to facilitate drug removal, and kept in darkness at 25 ºC for 15 days. After this period, eggs were exposed to light for 2 h to stimulate the hatching of miracidia. Hatched and unhatched (undeveloped) eggs were evaluated using an optical microscope and the ovicidal activity, expressed as a percentage, was calculated. A total of 42 (Spain) and 28 (Argentine) F. hepatica isolates were assessed for ABZ-resistance. After the EHT, 4 (9%) isolates from Spain results ABZ-resistant. The EHT could be successfully performed in 28 Argentinian isolates, resulting 75% of them resistant to ABZ. The high prevalence of ABZ-resistance in F. hepatica observed in Argentine can be explained by the widespread use of this flukicidal drug instead of triclabendazole. Oppositely, the low ABZ-resistance observed in the isolates collected from Spain may be related to the common use of a variety of alternative flukicidal drugs, such as closantel, nitroxynil and/or clorsulon.