Overview and Approaches for Handling of Animal Models of Leishmaniasis

Abstract

Leishmaniasis, a disease of global relevance, results from infection with the protozoan parasite, Leishmania, which is transmitted to susceptible hosts through the bite of sand flies. Multiple forms of leishmaniasis may occur, including cutaneous, mucocutaneous, and visceral. Research with animal models remains an important approach to help define basic pathophysi- ologic processes associated with infection and disease. In this regard, mice and hamsters represent the most commonly used models. The severity of leishmaniasis in animal models depends on several factors, including genotype of the host and parasite and the dose and route of administration of the parasite to the host, and severity of outcome may range from subclinical to severe illness. This review provides basic background on leishmaniasis, relevant animal models, the pathophysiology and clinical signs in animals used as models of leishmaniasis, and general approaches to mitigate risk to personnel.

Figure 1.

Life cycle of Leishmania. Image courtesy of DPDx, Centers for Disease Control and Prevention (https://www.cdc.gov/dpdx.). Infected sand flies transmit promastigotes to a host when taking a blood meal. Following internalization by host phagocytic cells, the amastigote form of the parasite multiplies and can infect other cells. A subsequent blood meal taken by another sand fly results in transmission of the parasite to the vector where the amastigotes transform in the gut to promastigotes, which then migrate to the proboscis and prepare to infect other hosts during ingestion of a blood meal, thus completing the cycle.

Figure 2.

Amastigotes of Leishmania sp. (A) In a biopsy specimen from a skin lesion, stained with hematoxylin and eosin. Leishmania sp. (B) Promastigotes from culture. Images courtesy of DPDx, Centers for Disease Control and Prevention (https://www.cdc.gov/dpdx.).

Figure 3.

Induration and ulceration (arrow) of the pinna in a BALB/c mouse experimentally infected with Leishmania. Photo courtesy of Dr. Mary Ann McDowell.

Figure 4.

Induration and ulceration of the foot pad of a mouse experimentally infected with Leishmania. The arrows outline the area of cutaneous ulceration. Photo courtesy of Dr. Mary Ann McDowell.

Figure 5.

An adult sand fly containment system designed to facilitate blood meals on live, anesthetized animals. Sand flies are housed within the polycarbonate chamber, and anesthetized animals are placed in the cloth sleeve that is then inverted into the box through which sand flies can take a blood meal from the animal. Photo courtesy of Dr. Mary Ann McDowell.