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Leishmania infantum xenodiagnosis from vertically infected dogs reveals significant skin tropism
Journal article   Open access   Peer reviewed

Leishmania infantum xenodiagnosis from vertically infected dogs reveals significant skin tropism

Breanna M Scorza, Kurayi G Mahachi, Arin C Cox, Angela J Toepp, Adam Leal-Lima, Anurag Kumar Kushwaha, Patrick Kelly, Claudio Meneses, Geneva Wilson, Katherine N Gibson-Corley, …
PLoS neglected tropical diseases, Vol.15(10), pp.e0009366-e0009366
10/2021
DOI: 10.1371/JOURNAL.PNTD.0009366
PMCID: PMC8523039
PMID: 34613967
url
https://doi.org/10.1371/journal.pntd.0009366View
Published (Version of record) Open Access

Abstract

Dogs are the primary reservoir for human visceral leishmaniasis due to Leishmania infantum. Phlebotomine sand flies maintain zoonotic transmission of parasites between dogs and humans. A subset of dogs is infected transplacentally during gestation, but at what stage of the clinical spectrum vertically infected dogs contribute to the infected sand fly pool is unknown. We examined infectiousness of dogs vertically infected with L. infantum from multiple clinical states to the vector Lutzomyia longipalpis using xenodiagnosis and found that vertically infected dogs were infectious to sand flies at differing rates. Dogs with mild to moderate disease showed significantly higher transmission to the vector than dogs with subclinical or severe disease. We documented a substantial parasite burden in the skin of vertically infected dogs by RT-qPCR, despite these dogs not having received intradermal parasites via sand flies. There was a highly significant correlation between skin parasite burden at the feeding site and sand fly parasite uptake. This suggests dogs with high skin parasite burden contribute the most to the infected sand fly pool. Although skin parasite load and parasitemia correlated with one another, the average parasite number detected in skin was significantly higher compared to blood in matched subjects. Thus, dermal resident parasites were infectious to sand flies from dogs without detectable parasitemia. Together, our data implicate skin parasite burden and earlier clinical status as stronger indicators of outward transmission potential than blood parasite burden. Our studies of a population of dogs without vector transmission highlights the need to consider canine vertical transmission in surveillance and prevention strategies.
Pregnancy Animals Dog Diseases - diagnosis Dog Diseases - parasitology Dog Diseases - transmission Dogs Female Infectious Disease Transmission, Vertical Insect Vectors - parasitology Insect Vectors - physiology Leishmania infantum - genetics Leishmania infantum - isolation & purification Leishmania infantum - physiology Leishmaniasis, Visceral - diagnosis Leishmaniasis, Visceral - parasitology Leishmaniasis, Visceral - transmission Leishmaniasis, Visceral - veterinary Male Parasite Load Placenta - parasitology Psychodidae - parasitology Psychodidae - physiology Skin - parasitology Tropism Xenodiagnosis

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