# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 13 _Balantioides coli_  
_Balantioides coli_, clade Sar Alveolata, phylum Ciliophora, family Balantididae [2], is the only ciliated protozoan and the largest among those infecting humans [280]. Balantidiasis is a neglected parasitic infection of zoonotic significance and worldwide distribution, most frequent in subtropical and tropical regions [281].  
_B. coli_ is considered a commensal of the intestine in several mammalian hosts. The main reservoirs are domestic and wild pigs as well as wild bours, which carry the parasite in the large intestine. Its life cycle comprises the cyst and trophozoite stages [280; 281]. A prevalence of 0.02%-1% reported in human hosts might be an underestimation since the infection most often remains asymptomatic [280]. High prevalence values reported for Latin America, the Philippines, Papua New Guinea, and the Middle East regarded pig farmers for 29% of the studies. Transmission may occur by ingesting food and water contaminated with cysts beyond contact with animals. Predisposing factors for illness manifestation are malnutrition, ongoing infections, and debilitating diseases [280]. Symptomatic cases present loose feces or watery diarrhea, loss of appetite and body condition, dehydration, and retarded growth. Severe cases manifest with ulceration of the intestinal mucosa and bloody diarrhea with possible fatal outcomes, liver abscess, vertebral osteomyelitisitis, and myelopathy [280; 281]. Extra-intestinal infections may occur through dissemination into the appendix, liver, peritoneum, lung, and genitourinary tract, especially in immunocompromised individuals. Uterine infection, vaginitis, andystitis may occur through direct spread from the anal area or rectovaginal fistula [280].  
A recent case of urinary tract _B. coli_ infection was casually discovered during routine analysis for preeclampsia and preterm delivery in a 24-year-old pregnant woman in Northwest Ethiopia. The patient might have acquired the infectious agent by contact with goats, sheep, and other domestic animals or by eating raw vegetables. This was probably facilitated by immune suppression in pregnancy [280]. A symptomatic case regarded a 48-year-old Thai woman with a 3-month history of intermittent swelling of both lower limbs who was found to be affected by a urinary tract infection caused by _B. coli_. The patient had no direct contact with pigs, but most probably ingested cysts through water or food, possibly an undercooked grilled pig intestine dish popular in some parts of Thailand [282].  
_B. coli_ is frequently found in pigs, and a recent study carried out in southern Italy showed that of 177 samples from swine reared and slaughtered locally, 46.89% tested positive for _B. coli_. The infection rate was significantly higher in commercial hybrid races (64.84%) compared to the autochthonous breed (27.91%) and significantly higher in pigs reared in the intensive system, possibly due to the increased difficulty of maintaining hygienic conditions. _B. coli_ was previously found to be highly prevalent in other national and European areas. However, its public health significance has been poorly considered, despite its high risk of zoonotic transmission. Since _B. coli_ can survive on carcass surfaces, good slaughtering hygiene is essential to prevent transmission [281].  
The presence of this parasite on leafy greens marketed was recently reported in Brazil and Mozambique and also in older studies [82; 84; 283].