Dr. Ricardo Molina from the Servicio de Parasitología at the Centro Nacional de Microbiología of the Instituto de Salud Carlos III in Madrid, Spain, and his colleagues performed a cross-sectional serological survey on the epidemiology of canine leishmaniosis (CanL) in the years 2006 and 2007 in the region of Madrid. Because of its wide altitude range and because CanL is endemic, the area around the Sistema Central was used as a study region.

The researchers examined a total of 1076 dogs from 32 villages for clinical signs of CanL. They took serum samples for detection of several hematological and biochemical variables. To identify Leishmaniosis-specific antibodies, Molina and his associates performed an indirect immunofluorescence antibody test (IFAT).

87 of the 1076 dogs were seropositive for CanL (IFAT: cut-off ≥ 1/80), which equals a seroprevalence of 8.1% (0 to 16.1%, depending on the village), the authors wrote. When considering the results of physical examination and the biochemical/hematological status of each dog, 32 of the 87 dogs were regarded as clinically healthy (37%). Interestingly, seropositive results were found most often in young dogs (one to two years of age) and old dogs (seven to eight years).

Molina and his research team determined infection risk factors: age (OR = 1.15; 95% CI: 1.04-2.29), weight (OR = 1.10; 95% CI: 1.04–1.16), and living outdoors as opposed to in a home (OR = 3.38; 95% CI: 1.42–8.05). Compared to data collected in 1992 from the same area, the seroprevalence of CanL seems to have increased by 1.54 (95% CI: 1.04-2.29).

The authors postulate that “this increasing trend cannot be attributed to differences in the sociodemographic characteristics of dog populations”, therefore environmental factors “could have had an impact on vector and reservoir densities and their geographical distributions.” Thus, they recommend performing more studies to find possible reasons for this trend by trying to correlate sand fly densities and CanL seroprevalences with climate, land use and human changes.

The project was part of the EDEN (Emerging Diseases in a changing European eNvironment) project of the Euopean Commission. The aim is to identify and catalogue European ecosystems and environmental conditions that play a role in spatial and temporal distributions and dynamics of assorted pathogens including Leishmania infantum (EDEN-LEI).

References

• Vet. Parasit. 169(3-4):327-334