Microfilaria in a panther chameleon
Kristiina Ruotsalo
Animal Health Laboratory, University of Guelph, Guelph, ON.
AHL Newsletter 2022;26(3):21.
Direct smears of material obtained from scrapings of hyperkeratotic lesions on the lips and commissures of the mouth in a panther chameleon were examined cytologically. No additional clinical information was provided.
The slides contained mildly hemorrhagic backgrounds with clusters of both parabasal and superficial keratinized squamous epithelial cells intermixed with moderate numbers of lytic heterophils. Free heterophil granules were present within the slide backgrounds, along with numerous pleiomorphic extracellular bacteria, most consistent with resident flora. Also found were frequent extracellular microfilaria which exhibited both blunted and tapered ends, and a small clear sheath over the entire organism. Internal structures appeared coarsely granular in nature. These microfilaria were interpreted to most likely represent Foleyella spp., due to the presence of the loose sheath which completely enclosed the microfilaria. Definitive identification would require evaluation of an adult worm.
Filarial nematodes of various genera can affect reptiles. Foleyella furcata and Foleyella brevicauda are commonly reported in chameleons from Madagascar. In affected chameleons, adult worms are found in subcutaneous tissues. Following fertilization, the female worm releases large numbers of microfilaria into peripheral blood. Blood sucking arthropods such as Culex and Aedes mosquitoes serve as intermediate hosts, and transmit the infective larval stages to other reptiles. Thus, microfilaria can be found in peripheral blood, and adult worms are located within subcutaneous tissues and body cavities of affected animals. Most infections by Foleyella spp. are asymptomatic; however, heavy infestations and the anatomic location of the adult worms could produce pathologic changes such as thrombosis, edema and necrosis, with associated clinical signs. Immunosuppression or concurrent disease could possibly worsen the clinical signs and lesions.
It was unclear if the microfilaria identified in this submission were simply an incidental finding, an indicator of underlying poor health due to disease, husbandry, or nutritional issues, or if this organism contributed directly to this patient’s clinically identified lesions. Ideally, a peripheral blood smear would have been assessed to ascertain the overall burden of microfilaria, and the hyperkeratotic lesions would have been evaluated histologically. Unfortunately no follow up testing was undertaken. AHL
Figure 1. Microfilaria on a background of individual epithelial cells aspirated from a hyperkeratotic lesion on the commissure of the mouth. Wright’s stain. (Image courtesy of Dr. Felipe Reggeti.)
References
1. Irizarry- Rovira A, et al. Blood smear from a wild-caught panther chameleon (Furcifer pardalis). Vet Clin Path 2002;31:129-131.
2. Maia JP, et al. Microscopic and molecular characterization of Hepatozoon domerguei (Apicomplexa) and Foleyella furcata (Nematoda) in wild endemic reptiles from Madagascar. Parasite 2014;2:25. http://dx.doi.org/10.1051/parasite/2014046