Parelaphostrongylus andersoni, the muscle worm, and P. tenuis, the meningeal worm, both use the white-tailed deer (WTD, Odocoileus virginianus) as their definitive host and terrestrial gastropods as intermediate hosts. Immunodiagnostic data indicate that Parelaphostrongylus species excretory-secretory L3 larvae antigens are serologically cross-reactive, leading to the belief that a prior infection of one species could grant adaptive immunity to other.2,3 Data on prevalence of Parelaphostrongylus species in Florida are limited; it appears that P. andersoni may occur in greater numbers in Florida than in other regions.1,2 A novel probe hybridization quantitative polymerase chain reaction (qPCR) assay targeting the cytochrome oxidase I (COI) gene of P. andersoni was developed. qPCR data were used to estimate the prevalence and distribution of P. andersoni in snails in Florida, as well as to determine specific snail species that can act as intermediate hosts. Samples examined for P. andersoni included 1,178 DNA extracts of aquatic and terrestrial gastropods, which represented 24 species from 15 counties throughout Florida. Twenty-five samples (2.12%) were positive for P. andersoni using the qPCR assay in four Florida counties, and three (0.25%) were verified as positive with a hemi-nested PCR assay and subsequent nucleotide sequencing. The three verified cases were found in Alachua and Hillsborough counties in Bradybaena similaris, a non-native, terrestrial gastropod species that is an intermediate for other nematodes, such as Angiostrongylus cantonensis. This study describes a newly recorded intermediate host and expands upon the historical range of P. andersoni in Florida, which is largely unknown in the literature.1,2 Identification of B. similaris as a viable intermediate host may aid in development of a culture system for P. andersoni. Once a culture system is developed, P. andersoni may be used to develop a vaccine for WTD protective against P. tenuis.
The authors would like to thank the Cervidae Health Research Initiative (CHeRI) for providing funding for this study. They would also like to thank the Merial Summer Scholars Program for providing research support.
Thank you to the Aquatics Pathobiology Laboratory at the University of Florida Emerging Diseases Institute for providing the laboratory equipment and space to complete the study.
1. Asmundsson IM, Mortenson JA, Hoberg EP. Muscleworms, Parelaphostrongylus andersoni (Nematoda: Protostrongylidae), discovered in Columbia white-tailed deer from Oregon and Washington: implications for biogeography and host associations. J Wildl Dis. 2008;44:16–27.
2. Lankester MW. Extrapulmonary lungworms of cervids. In: Samuel MW, Pybus MJ, Kocan AA, eds. Parasitic Diseases of Wild Mammals. 2nd ed. Wiley-Blackwell; 2001:228–278.
3. Ogunremi O, Lankester M, Loran S, Gajadhar A. Evaluation of excretory-secretory products and somatic worm antigens for the serodiagnosis of experimental Parelaphostrongylus tenuis infection in white-tailed deer. J Vet Diagn Invest. 1999; 11(6):515–521.