Parasitism and inflammation in ear skin and in genital tissues of symptomatic and asymptomatic male dogs with visceral leishmaniasis

Abstract

Canine visceral leishmaniasis (CVL) is transmitted through vector, although venereal transmission has been suggested. This study aimed to compare the parasitic loads and inflammatory processes in genital tissues with ear skin from seropositive male dogs. Forty-five seropositive dogs were separated into groups containing symptomatic (n = 23) and asymptomatic (n = 22) animals. The control group (n = 2) healthy animals with seronegative and negative results in direct parasitological test. Samples of ear tip skin, prepuce, glans penis, testis, epididymis, and prostate were collected for evaluation of parasitic load and inflammatory infiltrate. Although ear tip skin was the most intensely parasitized, prepuce and epididymis revealed no difference in parasitism when compared with ear tip skin (P > 0.05). Parasitic loads in testis and prostate were lower than other tissues (P < 0.05). Parasitism in glans penis was high, similar to prepuce and epididymis, but lower than ear tip skin. High parasitism was more frequent in symptomatic dogs than asymptomatic animals. Severe inflammatory processes were more frequent within the symptomatic animals compared with asymptomatic and more predominant in prepuce and epididymis. Ear tip skin and genital tissues presented signs of chronic inflammation. There were weak and moderate positive correlations between parasitic loads and inflammatory processes. Our results demonstrate that, likewise with the ear tip skin, the genital of seropositive dogs can carry a large number of Leishmania infantum amastigotes and this process are more intense in symptomatic animals. These data have important implications for understanding the possibility of venereal transmission of CVL.

Frequency, active infection and load of Leishmania infantum and associated histological alterations in the genital tract of male and female dogs

“…These results suggest that the intensity of inflammation in the genital tract of dogs is associated with L . infantum load, in agreement with other authors [ 2 , 15 ].…”

“…After infection, the parasite can spread through the blood or lymphatic system to other organs of the genital tract. The high frequencies of positive results in vulvar skin observed in this study and in vulvar skin and prepuce reported in other studies [ 2 , 11 , 13 , 15 ] support that this route of infection of the genital tract may occur. However, future experimental studies on the kinetics of genital tract infection with L .…”

“…The lower frequency and load of L . infantum in the prostate compared to the epididymis and testis observed in this study and in others [ 4 , 11 , 15 ] may be due to a more efficient innate and adaptive immunity against L . infantum in this organ.…”

“…In venereal transmission, infection would first occur in the male and female external genital organs during copulation. In males, the infection would then spread via the hematogenous or lymphatic route from the penis, which shows a high frequency of this parasite in the prepuce, glans penis and smegma [ 10 , 11 , 13 , 15 ], to the testis, epididymis and prostate. In females, the infection would spread via the hematogenous or lymphatic route from the vulva and vagina to the uterus, uterine tubes and ovaries.…”

“…infantum load in the testis, epididymis, glans and prepuce of dogs with clinical signs of CVL compared to those without signs of the disease [ 15 ]. Thus, the results of that study [ 15 ] and the present findings suggest that, among both males and females, the potential of venereal transmission is higher in animals with clinical signs compatible with CVL. However, this hypothesis needs to be confirmed.…”