Balantidium coli in Pigs of Distinct Animal Husbandry Categories and Different Hygienic-Sanitary Standards in the Central Region of Rio Grande do Sul State, Brazil

Abstract

Background: Balantidium coli is a commensal protozoan that infects several animals, but it has pigs as its natural reservoir. In the presence of predisposing factors, B. coli can become pathogenic for swine, causing enteric lesions. Infections determined by this protozoan may be a risk to public health, due to dysentery in animal keepers and veterinarians. This study aimed to determine the occurrence of infection by B. coli in pigs of distinct husbandry categories, as well as unlike physiological state, kept in farms with different hygienic-sanitary standards, located in the central region of Rio Grande do Sul State in Brazil.

Materials, Methods & Results: Stool samples were collected from 12 different farms with different hygienic-sanitary standards being four farms of finisher pigs (G1; n = 287), four farms with pregnant females (G2; n = 60) and four farms with lactation sows (G3;  n = 40), and all samples were submitted to coproparasitological analyses to verify the presence of cysts or trophozoites of B. coli. The infection levels were considered mild (1-100 cyst/trophozoite), moderate (101300 cyst/trophozoite) and high (>300 cysts/trophozoite). In addition, information about hygienic-sanitary conditions of each farm was collected. The occurrence of B. coli infection in all swine stool samples analyzed was 60.9% (236/387); however, in G1, G2 and G3 was 54.7% (157/287), 91.7% (55/60) and 65% (26/40) respectively. There was significant difference in the occurrence of G1 (P < 0.05) except between farms B and C (67.9% and 56.6% respectively). There was also a significant difference (P < 0.05) between the occurrence of B. coli found in G2 and G3. The infection levels were considered predominantly mild in G1; and mild to moderate in G2 and G3.

Discussion: In this research it was confirmed the presence of B. coli in swine farms located in the central region of Rio Grande do Sul State in Brazil. This area is known as being an important producer of pigs in Brazil. The results obtained in this study, demonstrated that swine farms with better hygienic and sanitary standards, had mild infections by B. coli. However, the presence of intestinal parasites, especially protozoa, can occur even in properties with good management practices. However, protozoa infections can cause important production losses, especially when associated with other pathogens or nutritional problems. The occurrence of B. coli observed in pregnant (G2) and lactating (G3) females was significant, and the infection level was mild to moderate. These conditions suggest that pregnancy, childbirth and lactation are critical stages for females, mainly due to physiological stress, resulting in a change in the hormonal levels and immune status of the animals. Thus, these factors cause declines in the immune response of pigs making them susceptible to infections and the increase of cyst excretion of B. coli in feces. The abundance of protozoan cysts in feces contaminates the environment and increases the risk of infections in humans. In addition, it was demonstrated the occurrence of B. coli in an important site of swine production in RS, Brazil. B. coli is related to the physiological state of the animals and the hygienic and sanitary management in different categories of swine. In conclusion, this study highlights the epidemiological importance of swine as natural reservoir of Balantidium coli and the risk potential of infection to animals and humans. Additionally, sanitary program in farming pigs must be improved in order to guarantee healthy and food-safe product for consumers.