Control of Histoplasmosis in Animals
In dogs and cats infected by the subspecies capsulatum or farciminosum, the treatment of choice is oral itraconazole. The recommended dose is 10 mg/kg q 12-24 h for a minimum of 4-6 months.
Treatment should be continued for at least 2 months after resolution of clinical signs (Bromel and Sykes 2005). In dogs, amphotericin B has been used successfully to treat local and disseminated histoplasmosis, but relapses are common.In horses infected by the variety farciminosum, most of reported treatments date back to the beginning of the twentieth century. Some of them (iodide, mercuric, arsenic or imidazole-derived drugs) were efficient, but were always long, relatively expensive and toxic. In combination with surgical removal of the lesion or cauterisation, these treatments led to recovery within 4-6 weeks (Guerin 2010). Amphotericin B is the listed drug of choice for the treatment of clinical cases of epizootic lymphangitis by the OIE (Anon 2004).
Elimination of the infection can be achieved by culling infected horses and application of strict hygiene practices to prevent spread of the organism. However, culling is hardly acceptable in highly endemic areas where the use of horse-drawn taxis and carts to generate an income is a means of survival for a significant number of families.
Boquet and Negre developed a vaccine against epizootic lymphangitis obtained from a yeast culture inactivated by heat (cited by Curasson 1942). Subcutaneous injections every 7 days during 5 weeks proved to be efficient for the treatment of horses. More recently, a live attenuated vaccine was developed and tested in China. This vaccine was reported to protect 75.5% of horses inoculated, with immunity persisting for more than 2 years (Zhang et al. 1986). This vaccine is not commercially available, and there were some issues of adverse reactions that would need addressing (Scantlebury et al. 2015).
5.8