Leishmania incidence and prevalence in U.S. hunting hounds maintained via vertical transmission

Toepp, Angela J.; Schaut, Robert G.; Scott, Benjamin; Mathur, Divida; Berens, Ali J.; Petersen, Christine A.

doi:10.1016/j.vprsr.2017.08.011

Cited by 14 publications

(22 citation statements)

References 49 publications

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“…Despite experimental studies that indicate that vector transmission of the Leishmania infantum found in US hunting dogs is possible, there is no evidence that vector transmission occurs naturally from the U.S. hunting dog population [34–36]. A decade of surveillance of this hunting hound population found that the prevalence of CanL from vertical transmission was higher than expected and similar to the rates seen in countries where VL is endemic [37, 38].…”

Section: Introductionmentioning

confidence: 97%

Maternal Leishmania infantum infection status has significant impact on leishmaniasis in offspring

et al. 2019

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Visceral Leishmaniasis is a deadly disease caused by Leishmania infantum , endemic in more than 98 countries across the globe. Although the most common means of transmission is via a sand fly vector, there is growing evidence that vertical transmission may be critical for maintaining L . infantum infection within the reservoir, canine, population. Vertical transmission is also an important cause of infant morbidity and mortality particularly in sub-Saharan Africa. While vertical transmission of visceralizing species of Leishmania has been reported around the globe, risk factors associated with this unique means of Leishmania transmission have not been identified therefore interventions regarding this means of transmission have been virtually non-existent. Furthermore, the basic reproductive number, (R 0 ), or number of new L . infantum infections that one infected mother or dam can cause has not been established for vertical transmission, also hampering the ability to assess the impact of this means of transmission within reservoir of human hosts. Canine Leishmaniosis (CanL) is enzootic within a U.S. hunting dog population. CanL is transmitted within this population via transplacental transmission with no reported vector transmission, despite many repeated attempts to find infected sand flies associated with these dogs and kennels. This population with predominantly, if not solely, vertical transmission of L . infantum was used to evaluate the critical risk factors for vertical transmission of Leishmania and establish the R 0 of vertical L . infantum infection. Evaluation of 124 animals born to eighteen dams diagnostically positive for infection with L . infantum showed that there was a 13.84x greater chance of being positive for L . infantum within their lifetime if the mother was also positive within her lifetime (RR: 13.84, 95% CI: 3.54–54.20, p-value: <0.0001). The basic reproductive number for vertically transmitted L . infantum within this cohort was 4.12. These results underscore that there is a high risk of L . infantum infection to transmit from mother to offspring. Targeted public health interventions and control efforts that address vertical transmission of L . infantum are necessary in endemic countries to eliminate visceral leishmaniasis.

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Section: Introductionmentioning

confidence: 97%

Maternal Leishmania infantum infection status has significant impact on leishmaniasis in offspring

et al. 2019

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“…Within the USA, leishmaniosis is enzootic within the hunting dog population with a qPCR prevalence of 20%, similar to rates of seroprevalence seen in countries with established sand fly-transmitted disease [14, 15]. CanL in the USA is transmitted vertically with no documented vector transmission [4, 16].…”

Section: Introductionmentioning

confidence: 99%

Comorbid infections induce progression of visceral leishmaniasis

et al. 2019

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BackgroundVisceral leishmaniasis (VL) is a vector borne zoonotic disease endemic in humans and dogs in Brazil. Due to the increased risk of human infection secondary to the presence of infected dogs, public health measures in Brazil mandate testing and culling of infected dogs. Despite this important relationship between human and canine infection, little is known about what makes the dog reservoir progress to clinical illness, significantly tied to infectiousness to sand flies. Dogs in endemic areas of Brazil are exposed to many tick-borne pathogens, which are likely to alter the immune environment and thus control of L. infantum.ResultsA cross-sectional study of 223 dogs from an area of Natal, in the Rio Grande do Norte, Brazil, were studied to determine the association between comorbid tick-borne disease and Leishmania infection in this endemic area. The risk of Leishmania seropositivity was 1.68× greater in dogs with tick-borne disease seropositivity compared to those without (Adjusted RR: 1.68, 95% CI: 1.09–2.61, P = 0.019). A longitudinal study of 214 hunting dogs in the USA was conducted to determine the causal relationship between infection with tick-borne diseases and progression of VL. Hunting dogs were evaluated three times across a full tick season to detect incident infection with tick-borne diseases. A logistic regression model with generalized estimating equations to estimate the parameters was used to determine how exposure to tick-borne disease altered VL progression over these three time points when controlling for other variables. Dogs infected with three or more tick-borne diseases were 11× more likely to be associated with progression to clinical VL than dogs with no tick-borne disease (Adjusted RR: 11.64, 95% CI: 1.22–110.99, P = 0.03). Dogs with exposure to both Leishmania spp. and tick-borne diseases were five times more likely to die during the study period (RR: 4.85, 95% CI: 1.65–14.24, P = 0.0051).ConclusionsComorbid tick-borne diseases dramatically increased the likelihood that a dog had clinical L. infantum infection, making them more likely to transmit infection to sand flies and people. As an important consequence, reduction of tick-borne disease exposure through topical or oral insecticides may be an important way to reduce progression and transmissibility of Leishmania infection from the canine reservoir to people.Electronic supplementary materialThe online version of this article (10.1186/s13071-019-3312-3) contains supplementary material, which is available to authorized users.

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“…This finding suggests a high risk of vertical transmission of the parasite, a fact already confirmed in dogs [ 36 – 41 ]. Vertical transmission of CVL is the main route of transmission in areas without demonstration of vector transmission, such as the United States, and may contribute to the maintenance of visceral leishmaniasis in endemic areas [ 12 , 40 , 41 ]. The lower frequency of active L .…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

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Visceral leishmaniasis caused by the protozoan Leishmania infantum is a zoonosis. The domestic dog is the primary reservoir in urban areas. This study aimed to evaluate the frequency, active infection and load of L . infantum in the genital tract of male and female dogs seropositive for this parasite, as well as to identify histological genital alterations associated with this protozoan. We studied 45 male and 25 female L . infantum -seropositive noncastrated dogs from the same endemic area in Brazil. Tissue samples from the testis, epididymis, prostate, vulva, vagina, and uterus were examined by singleplex qPCR and parasitological tests (histopathology, immunohistochemistry, and parasitological culture). The latter were performed for the detection of active infection (parasites able to multiply and to induce lesions). Forty-four (98%) males and 25 (100%) females were positive for L . infantum in the genital tract (epididymis: 98%; vulva: 92%; vagina: 92%; testis: 91%; uterus: 84%; prostate: 66%). Active infection in the genital tract was confirmed in 69% of males and 64% of females (32% in the uterus). Parasite loads were similar in the testis, vulva, epididymis and vagina and lower in the prostate. Only the parasite load in the vagina was significantly associated with the number of clinical signs. Granulomatous inflammation predominated in all organs, except for the prostate. Only in the testis and epididymis was the inflammatory infiltrate significantly more intense among dogs with a higher parasite load in these organs. The high frequency, detection of active infection and similarity of L . infantum loads in the genital tract of infected males and females suggest the potential of venereal transmission of this parasite by both sexes and of vertical transmission by females in the area studied. Additionally, vertical transmission may be frequent since active L . infantum infection was a common observation in the uterus.

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Leishmania incidence and prevalence in U.S. hunting hounds maintained via vertical transmission

Cited by 14 publications

References 49 publications

Maternal Leishmania infantum infection status has significant impact on leishmaniasis in offspring

Maternal Leishmania infantum infection status has significant impact on leishmaniasis in offspring

Comorbid infections induce progression of visceral leishmaniasis

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

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