Long-term follow-up of dogs with leishmaniosis treated with meglumine antimoniate plus allopurinol versus miltefosine plus allopurinol.

Background: Visceral leishmaniosis is a potentially life-threatening illness caused by a protozoan parasite of the genus Leishmania. It is found mainly in areas where both the parasite and its vector are endemic and is one of the most challenging infectious diseases in the world to control. HIV infected patients are vulnerable to Leishmania infections, and the main reservoir hosts of Leishmania infantum parasites are domestic dogs. Here, we evaluated the long-term efficacy of treatment with meglumine antimoniate plus allopurinol (G1) compared to miltefosine plus allopurinol (G2) in dogs naturally infected L. infantum.

Methods: Eighteen dogs with leishmaniosis were divided into the following two groups: G1 (n = 9) was treated subcutaneously with meglumine antimoniate (100 mg/kg/day/30 days) plus allopurinol (10 mg/kg/per day/30 days), while G2 (n = 9) was treated orally with miltefosine (2 mg/Kg/day/30 days) plus allopurinol (10 mg/kg/day/30 days). Thereafter, the same dose of allopurinol was administered to both groups for 6 years. Leishmania DNA in lymph node aspirates from the G1 and G2 dogs was quantified by real-time quantitative PCR at baseline and every 3 months for 24 months, and then at 28, 36, 48, 60 and 72 months. At each assessment, the dogs were examined for signs of disease, and their clinical scores were recorded.

Results: Both combination therapies produced significant clinical improvements in the dogs, with a significant reduction in the parasitic load in the lymph nodes of the dogs from both groups after 3 months of treatment. Clinical relapses were observed in four dogs from G2 (miltefosine/allopurinol), and just one dog from G1 (meglumine antimoniate/allopurinol). All dogs that relapsed had increased clinical scores, and increased anti-Leishmania antibody titers and parasitic loads in their lymph nodes.

Conclusions: Long-term, the clinical and laboratory findings of the G1 dogs were more stable than those of the G2 dogs, thus indicating that meglumine antimoniate had better clinical efficacy than miltefosine. The results suggest that treatment with allopurinol as a maintenance therapy is crucial for stabilizing the care of canine leishmaniosis.