EPIDEMIOLOGY AND MOLECULAR CHARACTERIZATION OF SELECTED PROTOZOA IN DOMESTIC RUMINANTS
Tesi di Dottorato
Data di Pubblicazione:
2021
Citazione:
EPIDEMIOLOGY AND MOLECULAR CHARACTERIZATION OF SELECTED PROTOZOA IN DOMESTIC RUMINANTS / L. Villa ; tutor: M. T. Manfredi ; coordinatore: V. Grieco. Dipartimento di Medicina Veterinaria, 2021 Jan 28. 33. ciclo, Anno Accademico 2020.
Abstract:
Apicomplexa parasites are single-celled, obligate intracellular cyst-forming protozoa, infecting humans and animals, that pose major threats to world health and global economy.
Among the most relevant species for farm animals, Besnoitia besnoiti, Neospora caninum and Toxoplasma gondii are parasites of medical (T. gondii) and veterinary (T. gondii, N. caninum, B. besnoiti) importance in domestic ruminants.
Bovine besnoitiosis, caused by Besnoitia besnoiti, is a chronic and debilitating parasitic disease of cattle, characterized by both cutaneous and systemic manifestations, compromising animal welfare and responsible for economic losses on affected farms. In Europe, including Italy, bovine besnoitiosis is an emerging or re-emerging disease, with an increasing geographical distribution and the number of cases of infection.
Neospora caninum, a coccidian protozoan, represents an important cause of bovine abortion. It was suggested that the parasite may have adverse effects on fertility and milk production, but only few and contrasting data are available to date. Besides, while only a single genotype of N. caninum exists worldwide, available parasite strains show considerable variation in vitro and in vivo, including different virulence in cattle. Microsatellite markers allow to fingerprint N. caninum isolates or DNAs and undertake population studies.
Toxoplasmosis represents an important public health issue, with the consumption of raw or undercooked meat being a major way of human infection. The role of beef in the transmission of the parasite to humans is questioned due to lower quantity of tissue cysts compared with other meat-producing species. However, the habit of consuming raw beef is regionally diffused, and the risk posed by Toxoplasma gondii infection in cattle should not be overlooked.
The aim of my doctoral thesis project was to investigate on the epidemiology and molecular characterization of selected protozoa parasites of medical and veterinary importance in domestic ruminants, i.e., B. besnoiti, N. caninum and T. gondii in cattle. A multidisciplinary approach based on clinical features, laboratory tests including serological and molecular techniques, was applied throughout the research project, to achieve a multi-level comprehension of the epidemiology of these parasite infections.
Three main research lines were developed:
Research Line 1: Exploring bovine besnoitiosis: a multi method approach.
A case of bovine besnoitiosis in a dairy farm housing 217 cattle in Italy was reported. A serological screening was performed on the whole herd using the recommended approach of ELISA and confirmatory Western Blot. Seropositive animals were clinically examined to reveal symptoms and lesions of besnoitiosis. Risk factors and the effects of the parasite infection on reproductive and productive performances were evaluated. Histopathology and molecular analyses on tissues from a slaughtered cow affected by the chronic phase of the disease were carried out. An overall seroprevalence of 23.5%, which increased up to 43.5% considering only cows, was recorded. Clinical examination of 33 of the seropositive cows evidenced the presence of tissue cysts in at least one of the typical localizations (sclera, vulva, or skin) in 25 animals. Statistical analysis did not evidence any significative impact of the parasite infection on herd efficiency; however, a decrease of productive parameters was recorded in cows showing cutaneous cysts. Concerning the chronically affected cow, histopathology revealed B. besnoiti tissue cysts in the skin of the neck, rump, hind legs, eyelid and vulva, in the muzzle, in mucosal membranes of the upper respiratory tract, and in the lungs. Parasite DNA was detected also in masseter muscles, tonsil
Tipologia IRIS:
Tesi di dottorato
Elenco autori:
L. Villa
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