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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #359928
Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: No evidence for air-borne transmission of Toxoplasma gondii in a very high prevalence area in Lancaster County

Author
item WADHAWAN, ABHISHEK - University Of Maryland School Of Medicine
item Hill, Dolores
item DAGDAG, ALINE - University Of Maryland School Of Medicine
item MOHYUDDIN, HIRA - University Of Maryland School Of Medicine
item DONNELLY, PATRICK - University Of Maryland School Of Medicine
item JONES, JEFFREY - University Of Maryland School Of Medicine
item POSTOLACHE, TEODOR - University Of Maryland School Of Medicine

Submitted to: Pteridines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2018
Publication Date: 12/31/2018
Citation: Wadhawan, A., Hill, D.E., Dagdag, A., Mohyuddin, H., Donnelly, P., Jones, J.L., Postolache, T.T. 2018. No evidence for air-borne transmission of Toxoplasma gondii in a very high prevalence area in Lancaster County. Pteridines. 29:172-178. https://doi.org/10.1515/pteridines-2018-0015.
DOI: https://doi.org/10.1515/pteridines-2018-0015

Interpretive Summary: Toxoplasma gondii (T. gondii) has been associated with acute food-borne illness, chronic low-grade inflammation, neuropsychiatric conditions and reactivation of chronic latent infection in immunocompetent hosts. Primary infection with T. gondii in pregnant women can lead to congenital toxoplasmosis. In addition to well-known oral tissue-cyst or oocyst ingestion, we hypothesized that the very high prevalence of T. gondii in certain populations exposed to agricultural dust could be, in part, a consequence of air-borne infection with oocysts.We collected environmental dust samples from an area with a reportedly high T. gondii seroprevalence in the Old Order Amish population, Lancaster, Pennsylvania. Samples included: a) air filters from air-conditioning units; b) swabs of settled dust; and c) vacuum filters containing air-borne field dust. Pools of the swabs and shredded sub-samples of the air filters were fed to pigs, with inoculation into mice of heart tissue from seroconverted pigs. We also investigated the presence of T. gondii DNA using PCR amplification. Only one pig seroconverted. However, bioassay of pig heart tissue further inoculated to mice showed no evidence of T. gondii infection. Consistently, no evidence of T. gondii DNA was revealed in any collected sample.

Technical Abstract: Vacuumed air-borne dust samples were dominated by the DNA from plants, animals and fungi (including Alternaria and Cladosporium - known allergens). However, no T. gondii was detected (though some unclassified Apicomplexan sequences were detected). ELISA results from the pigs indicated that only one pig had a low-positive seroconversion (0.365; positive cut-off: 0.30) that was initially detected at 6 weeks post-feeding of 100g of filter material from a round filter used to collect dust during horse/plow operation in an agricultural field. In fact, this low seropositive status persisted for the remainder of the experiment. However, all mice inoculated with heart tissue digest from this seroconverted pig were negative for the presence of T. gondii, based on microscopic observation of brain smears from each inoculated mouse. We found no evidence of T. gondii in collected samples of air filters, settled dust, or vacuumed air-borne dust. Viable T. gondii oocysts were either not present in these samples, or they were present in insufficient abundance to be detected.