Nachweis von Toxoplasma gondii in Mukelgewebe von experimentell infizierten Hühnern und Schweinen

Abstract

Toxoplasma gondii is one of the most common zoonotic parasites worldwide. The obligate intracellular tissue parasite has a broad range of intermediate hosts. Humans are often infec-ted by ingestion of tissue cysts in raw or undercooked meat. Pigs and chickens as a food-producing animals represent an important source of infection for humans. A quantitative real-time PCR targeting the 529-bp fragment were used to investigate distribution and predilecti-on sits of T. gondii in different tissues of pigs and chickens after oral infection with oocysts, and to estimate the parasite burden in tissues of this host species. 10 pigs and 12 chickens were infected experimentally with different doses of Toxoplasma oocysts. Using the 529-bp- PCR, 90% of all infected pigs were tested positive for T. gondii-DNA, most frequently affec-ted tissues were the thigh muscles (70%) and abdominal muscles (60%). Followed by brain and foreleg (each 40% positive samples), while the heart (30%) and tongue (10%) were less frequently positive. T. gondii-DNA was also found in > 90% of all infected chickens, each 50% of all thigh muscles samples, breast muscle and brain were positive for T. gondii. The heart (approximately 20% positive samples) was less frequently positive. In pigs, parasite detection in tissue samples ranged from 0.1 - 4.1 parasites per 25 mg of tissue, in chickens, detection ranged from 0.1 - 4.9 parasites per 25 mg of tissue. This parasite quantity was in-dependent of the type of tissue. A reverse transcriptase real-time PCR was established to investigate the viability of parasite in the tissue of infected pigs and chickens by detection of T. gondii-mRNA in this tissues. The sensitivity of this method was lower than that observed for detection of T. gondii-DNA, and could not detect viable parasites in the positive samples tissues of infected pigs and chickens. Thus, muscle tissues represent predilection sites for the persistence of T. gondii in pigs and chickens which indicate that raw or undercooked meat or meat products is a potential risk for parasite transmission to humans.