Escola de Veterinária PUCMINAS, Bairro Angola, Betim, Minas Gerais; Clínica Veterinária Santo Agostinho, Minas Gerais, Brasil
Treatment of Canine Visceral Leishmaniasis (CVL) has been performed in Europe for 50 years and, as a preventive measure, Mancianti et al. (1988) demonstrated that antimony could be recommended to control the disease in dogs, by showing that its use prevented the development of the disease in 90% of asymptomatic animals. Gradoni et al. (1988) reported that the treatment of CVL with antimony as a control measure reduced the prevalence of CVL in 9,2% of the dogs of Elba Island. Alvar et al. (1994) treated dogs with antimony and allopurinol for short periods and reported, in addition to clinical improvement, that the animals remained non-infective for at least four months after treatment. The authors advocated a course of treatment for infected dogs during the transmission season of the disease in Europe, as a means to control transmission. Baneth et al. (2001) demonstrated that daily treatment with allopurinol would lead to a strong decrease in infectiousness of treated dogs toward L. longipalpis and considered that this measure could be applied in transmission areas. In Italy, prevention with topic insecticide imidacloprid/permethrin and treatment with pentavalent antimony and alopurinol for four years resulted in progressive reduction in prevalence and incidence of serologic reactivity for L. infantum in a dog shelter. The recurrence rate during this period was 8% among 67 seropositive dogs (Podaliri et al., 2009).
In Brazil, discussions on the treatment of CVL only started after the urbanization of the disease. In 1994, small animal veterinary experts started treating dogs as an alternative measure to culling infected dogs (Ribeiro, 2006). The sequence of the protocol for approaching and treating CVL was presented by Ribeiro & Michalick (2001) and Ribeiro (2007), starting with diagnostic confirmation, evaluation of laboratory findings to guide the choice of treatment protocol and conscious participation of the owner. Taking concurrent prophylactic measures in order to avoid the presence of the vector is imperative. During treatment, dogs should undergo a check up every three months.
Ribeiro et al. (2005), aiming at evaluating the impact of treatment associated to vector control in a dog shelter located at an endemic area in Belo Horizonte, Brazil, reported the interruption of transmission during the experiment--a period of two years. As a vector control measure, 4% deltamethrin impregnated collars were used in all dogs and all seropositive dogs were treated with allopurinol. After a two-year follow up, no new cases were registered in the shelter and one seropositive dog became seronegative. According to Ribeiro (2006), there was no occurrence of zoonotic visceral leishmaniasis in any of the residences that kept dogs submitted to treatment and followed the recommended protocols and safety measures. Transmission rate increases due to the excessive amount of reservoirs and vectors.
The Panamerican Health Organization (PAHO) considers that, in special situations, treatment of CVL can be performed if associated with measures that will prevent contact of the dog with the vector (PAHO, 2006).
Systematic vector control measures focusing the dogs, as the use of insecticide collars or topic insecticide should be applied by public health authorities.
The policy of dog culling adopted in Brazil is poorly accepted by the population. Treatment and culling of dogs are controversial and seem to be of little importance in what concerns the control of human disease expansion (Dye, 1996; Oliveira et al., 2008).
The protocols of treatment established for sick dogs offer good possibilities of clinical cure, low rates of recurrence and decrease or suppression of skin parasitism (Ribeiro, 2007). All of these factors suggest that treatment of CVL, associated with vector control measures, is efficient in mitigating transmission (PAHO, 2006). Immunotherapy and canine vaccination also ally to these factors (Ribeiro, 2007; Ribeiro et al., 2009).
There are two vaccines against CVL approved for use in Brazil. Their use as public health tools is being studied by public health authorities.
Therefore, a dog in treatment, adequately protected from proximity to the vector and regularly followed by a veterinarian, does not seem to us to be a risk for public health. This condition might become positive regarding disease control in what it inserts veterinarians in the education of the population focusing on the prevention of new cases and on managing infected dogs. The veterinarian informs the population, on an individual basis, about the benefits of using tools that can prevent transmission by the vector and about the correct choice and use of the vaccines available.
Nevertheless, new studies that address this subject are needed, always based on the principle of searching new ways to preserve life, and not on the intent of consolidating the policy of death.
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