Leishmaniasis, an emerging disease found in companion animals in the United States

Abstract

This review discusses leishmaniasis in cats and dogs in the United States. Leishmaniasis is endemic in Foxhound populations in the United States and is still being characterized in this group. Pathophysiology, clinical signs, transmission, immunology, and treatment are examined in this review. Leishmaniasis is an emergent zoonosis of great public health significance.

Figure 1

Different Leishmania diagnostics are more or less effective due to alterations in parasite load and immune response. Due to cost and materials required, serology is the most common means of diagnosing Leishmania infection, both in the United States and elsewhere. The antibody response measured by serology can be against the whole parasite, for example the CDC IFA assay (CDC, light blue bar) or to a specific antigen, for example the Cornell-developed kELISA (kELISA, dark blue bar). This difference; whole parasite response vs. specific antigen in this case, may lead to different sensitivity and specificity to detecting infection. Whole parasite-based serology can also cross-react with antibodies to Trypanosoma cruzi, for instance. kELISA has been shown to identify infection earlier, as portrayed by the x-axis, and may detect a different subset of antibodies (non-productive and productive antibodies are portrayed by the bottom two sets of dashed lines). T cell based responses, for instance T cell proliferation to parasite antigen (TCP, tan bar) detects infection very early after infection and is able to consistently indicate infection throughout the course of infection until very late in disease when the T cell response wanes (small dashed line). Unfortunately this assay is currently only performed on an experimental basis due to the time and materials required for successful analysis of this cellular response. Measurement of actual parasites in the blood stream (solid line) via detection of parasite kinetoplast DNA via quantitative polymerase chain reaction (PCR, orange bar) is another highly sensitive means of diagnosing parasite infection. This assay requires very rigid quality control to assure accurate results and due to the nature of the test can lead to occasional false positive results.