**2.5. Risk factors**

There is no consensus on the risk factors associated with CVL, as results differ between the studied Brazilian regions and between countries.

In Croatia, risk factors were sex (male), age (the two most prevalent groups comprise dogs between 3 and 4 years old and between 6 and 7 years old), and location (dogs in some cities are more likely to acquire the disease) [30]. In Spain, seroprevalence was also found to have bimodal age distribution, but the age groups were between 1 and 2 years and between 7 and 8 years; infection is also related to outdoor rearing [64]. In Portugal, risk factors are outdoor rearing, age (over two years), short fur, pure breeds, and location (dogs in the hinterlands are more likely to be affected) [29].

In Brazil, Belo et al. [62] conducted a systematic review of the literature on risk factors associated with CVL, and the variables that showed significant association with infection were short hair, pure breed, rearing restricted to house surroundings, and the presence of green areas adjacent to the house. The occurrence of CVL was also associated with the presence of poultry in domestic environment, free-living dogs, sex (male), and age greater than 1 or 2 years, although these associations were not statistically significant [62].

Another study in Brazil defined risk factors as outdoor rearing, contact with poultry, dogs living in rural areas, the presence of organic matter, the absence of environmental management, and proximity to forests [65]. As for dogs in the countryside, in an endemic area of Northeastern Brazil, the only identified risk factor found was sex, as male dogs were twice as likely to develop the disease [66].
