Note on the importance of nitroxynil in the control of bovine Fasciola gigantica infection in Madagascar

Abstract

Beyond infectious virus or bacterial diseases, the bovine fasciolosis with Fasciola gigantica is, by far, the most important scourge of Malagasy breeding, by the numerous economical losses it caused, whether directly or indirectly: mortality, slackening of the growth, infertility, incapacity to work, immunodepression thwarting the efficiency of vaccines. Recent works gave interesting elements to measure its impact. They progressively spread throughout the totality of the infected zones to be able to evaluate with precision the economical incidence of the disease and the profitability of the control measures. The intervention schemes are simple:

- Destruction of adult parasite by use of a fasciolicide: aqueous solution with  25 % nitroxynil, injectable subcutaneously, largely employed and well-known by breeders.

- Action on the intermediary host mollusc (Lymnaea natalensis) by biological means already well-proven in Madagascar: breeding of ducks or other exotic predators in watering places or rice-fields.

Data supplied by epizootiological surveys about distomatosis with Fasciola gigantica allow determining the cattle infection periods, with a corollary, a programme of systematic treatments with nitroxynil of ail the animals in a defined area. The experiment of regular treatments with nitroxynil showed:

- Its efficiency, proven by a quicker fattening of treated animals;

- Its long-term effect, preventing the re-infestations and assuring a lasting weight regain;

- Its innocuity (good local and general tolerance, no toxicity for the calves not weaned);

- Its compatibility with vaccination campaigns against infectious diseases, among others, anthrax.

Jointly, action on the intermediary hosts by palmipeds and other predators reduces largely the infesting forms, metacercarias of Fasciola gigantica and furcocercarias of Schistosoma spp. This means thus is susceptible to contribute also to the control against human trematodosis.