The survey took place in the rural areas of Wen xian county and Diebu County, Gansu Province. The main purpose of the villagers' dogs was to guard the homes and nursing homes, and most of the dogs were tied up in the corners of the homes. There are a lot of dogs and very few livestock kept in the villages in study area, so dogs are an easy source of blood meal for sandflies. The survey raises the dog the parasite infection is tied to the dog three times higher risk may be due to putting the dog is tied to the dog range is bigger, raises the dog often follow dog owners into the wild fields and mountain stream, often free access to the village inside and outside activities, and Gansu Leishmaniasis media is sand fly mainly wild habitat the sand fly, so put the dog activity increases the chances of the sand fly, resulting in an increased risk of infection[22, 23]. Dogs without kennels were 1.9 times more at risk of infection than dogs with kennels, again due to the greater risk of infection in the open air.
The risk of CVL infection in purebred dogs in this study was 1.8 times higher than that in mongrels (95%CI0.999-3.311).This is consistent with the finding by Solano-Gallego et al that hybrids are a protective factor, that they are less likely to be infected, that hybrids have developed a degree of resistance, and that pure-bred dogs are at risk[24]. Our study also found that short-haired dogs are more susceptible to infection than long-haired dogs, and there is a significant difference, which is consistent with the results that short-haired dogs have a significantly higher probability of infection than long-haired dogs[25]. In fact, sand fly bite dogs were more likely to choose the face with less hair, around the nostril, muzzle edge, and perianal area. Long-haired dogs in the survey sites were never trimmed, and many long-haired dogs had their face covered with fur, so short-haired dogs were more likely to be bitten and infected by sandflies[26].
In the univariate analysis, the age, height and weight of the dogs were statistically significant. There was a significant difference in Leishmania infection rates between puppies and adults, and we found a higher risk of Leishmania infection in puppies younger than 2 years of age[27]. And the greater the height and weight of the dog, the greater the exposure, and the higher the risk of Leishmania infection. According to foreign studies, Leishmania infection is more easily acquired in dogs under 3 years of age[28]. Puppies are more susceptible to infection due to congenital immaturity, a lack of internal immune barriers, malnutrition and the sand fly's affinity for this group[29]. We found that although the age, height, weight and other factors in the univariate study were statistically significant, these factors were not the decisive factors affecting infection in the regression model because of the correlation strength.
Cvl-related symptoms do not actually occur immediately after Leishmania infection in dogs, which is called asymptomatic infection. In this study, a large percentage of infected dogs showed no obvious signs and symptoms, but asymptomatic dogs may exhibit a high parasite load and play an important role in CVL transmission[30, 31]. Over time, the physical condition, activity, mucosal signs, nail growth and other indicators of asymptomatic infected dogs changed[32]. Our study found that almost all dog owners did not actually know about CVL and were unaware that mucosal signs, toenail growth, etc., were symptoms of CVL development, thus neglecting the care and selection of dogs and allowing the disease to develop. The persistence of this phenomenon may result in more healthy dogs being infected[33]. Therefore, we believe that promoting owners to master basic KNOWLEDGE of CVL and taking active preventive measures and strengthening the management of sick dogs will help to reduce the spread of CVL.