Absence of Viable Toxoplasma gondii in Artisanal Raw-Milk Ewe Cheese Derived from Naturally Infected Animals

Abstract

The presence of viable Toxoplasma gondii was investigated in artisanal cheeses made from milk of naturally infected ewes. Ewe milk was analyzed beforehand for the presence and vitality of T. gondii by loop-mediated isothermal amplification (LAMP) and reverse-transcriptase PCR (RT-PCR), respectively. Cheeses were prepared from raw milk following a traditional cheesemaking process. The cheese obtained from T. gondii-positive milk was analyzed by LAMP to detect Toxoplasma DNA-positive samples. RT-PCR was then carried out to assess the viability of the parasites in T. gondii-positive milk samples and fresh cheese, after 5 and 15 days of ripening. Physical-chemical parameters of cheeses were also investigated. All cheese samples derived from T. gondii-positive milk were positive according to LAMP, at both 5 and 15 days of ripening, while none of the samples were positive according to RT-PCR. Thus, while the presence of the parasite was demonstrated by the detection of specific DNA, the absence of detectable T. gondii RNA supports the hypothesis that changes in the chemical and physical characteristics occurring during the cheesemaking process and ripening period, could be sufficient to inactivate viable T. gondii in milk, minimizing the risk of human infection through consumption of raw sheep milk cheese.

Milk as a Non-Invasive and Alternative Sample for Serum in the Diagnosis of Animal Toxoplasmosis: A Systematic Review

“…The selected articles were performed in the UK (15), Italy (16)(17)(18)(19)(20)(21)(22)(23), Slovak Republic (24,25), Tunisia (26), Poland (27,28), Malaysia (6), Mongolia (29), China (8), Iran (14,(30)(31)(32)(33), Brazil (34)(35)(36)(37)(38)(39), Egypt (13,(40)(41)(42)(43)(44), and Iraq (45). In 28 descriptive studies, 6576 milk samples were evaluated using different molecular techniques such as polymerase chain reaction (PCR), realtime PCR, reverse-transcriptase PCR (RT-PCR), nested-PCR, and loop-mediated isothermal am-plification (LAMP) for identification of the T. gondii DNA that 332 out of these samples (5.05%) were positive.…”

“…According to Table 1, the lowest and highest seroprevalence rates of anti-T. gondii antibodies in milk samples were related to the studies as 4.61% (41/889) (14) and 63.18% (242/383) (22). Additionally, the lowest and highest prevalence rates of T. gondii in milk samples using molecular methods were observed in studies as 0% (0/14) (6) and as 100% (16/16) (23). Differences in prevalence may be attributed to different climatic characteristics, the examined populations, sensitivity and specificity of detection techniques, cultural, hygienic, and nutritional habits, breeding conditions and management of animals, immune status, the timing of infection, the genetic composition of the host and the organism, or distribution and behavior of cats (38,40,(53)(54)(55)(56).…”

Review: Potential Transmission of Toxoplasmosis through Consumption of Raw Goat’s Milk

“…On the contrary, Ranucci et al (2020), the cheese-making procedure was able to inactivate the parasite, as evidenced by the absence of T. gondii RNA by RT-PCR after 5 days of ripening. However, this study did not provide quantitative data regarding the amount of T. gondii in milk samples, so further research is recommended to determine the viable fate of T. gondii in the case of tachyzoites in milk, prior to cheese making.…”

Molecular surveillance of Toxoplasma gondii in raw milk and Artisan cheese of sheep, goat, cow and water buffalo origin

“…Toxoplasma gondii has three infectious stages in its life cycle: tachyzoites, bradyzoites in tissue cysts and sporozoites in sporulated oocysts. The farm animals, especially sheep and goats, are considered a major reservoir of T. gondii infection for humans and other carnivores (Ranucci et al 2020). Toxoplasmosis causes significant economic losses in livestock animals due to death, abortion, neonatal mortality, and production losses as well as it represents a serious global public health threat by leading to serious complications, especially in immunocompromised people and pregnant women (Ahmed et al 2014).…”