Balantidiasis is a protozoal intestinal infection caused by ciliated infusoria – balantidias. Clinical manifestations are a reflection of inflammatory and ulcerative processes in the large intestine, and are characterized by abdominal pain, tenesmus, frequent loose stools with an admixture of blood and pus, weight loss, intoxication syndrome. For the diagnosis, clinical and epidemiological data, the results of rectoromanoscopy, the detection of balantidias in feces and smears are important. Etiotropic therapy is performed with metronidazole, tinidazole, tetracycline antibiotics, monomycin.
Balantidiasis (infusion dysentery) is a zoonotic protozoal infection occurring with the phenomena of ulcerative hemorrhagic colitis and general intoxication. Outbreaks of balantidiasis occur more often in the southern regions, but sporadic cases of infection are also recorded in rural areas with developed pig farming. Disease is characterized by a severe course, and at the late start of treatment – high mortality due to intestinal complications, cachexia, and the addition of sepsis. The spread is facilitated by the lack of alertness on the part of medical specialists to this pathology, a low level of sanitary culture of the population, high invasiveness of the rural population (4-5%).
The etiological agent of balantidiasis is the ciliary infusoria Balantidium soli. Balantidia are the largest representatives of intestinal protozoa, parasitic in the human body. Their life cycle goes through 2 stages – cyst and vegetative. Balantidia cysts have a diameter of about 50 microns, a rounded shape and can remain viable outside the host body for 3-4 weeks. The length of vegetative forms of parasites is 30-150 microns, width is 30-100 microns; the surface is covered with cilia, thanks to which movement is carried out. In the external environment, vegetative forms are less stable – they die after 3-5 hours.
The main reservoir of pathogens of balantidiasis are pigs, among which the invasion reaches 60-80%; less often, a person acts as a source of protozoal infection. The mechanism of infection with balantidiasis is fecal-oral. Transmission of balantidia (more often cystic forms) occurs through dirty hands, contaminated water, fruits, vegetables. More often, workers of pig farms, slaughterhouses, and meat shops get sick with balantidiasis. In the human digestive tract, vegetative forms are formed from cysts that parasitize in the tissues of the blind, sigmoid and rectum. At the site of their introduction into the colon mucosa, areas of hyperemia and edema are formed, which later transform into erosions and ulcers. The defects of the mucous membrane have a crater-like shape, uneven edges, and a bottom covered with necrotic masses. Ulcerative-destructive changes in the intestine, absorption of toxic substances, as well as feeding of parasites at the expense of their host form the basis of the pathogenesis of balantidiasis and determine its clinical manifestations.
From the moment of infection to the manifestation of balantidiasis, 1 week passes. According to the severity of clinical manifestations, there are asymptomatic (subclinical) and manifest forms of balantidiasis, according to the nature of the course – acute, chronic and recurrent; according to the severity of the course – mild, moderate and severe.
In the subclinical form, intestinal dysfunction and intoxication are absent, and balantidiasis is recognized based on the endoscopic picture and laboratory data. The symptoms of the acute manifest form of balantidiasis resemble dysentery. Patients complain of progressive weakness, headache, febrile fever, nausea and vomiting. At the same time, signs of colitis develop: cutting abdominal pain, diarrhea, tenesmus. The stool becomes liquid, muco-purulent, and then bloody; it becomes more frequent up to 15-20 times a day; bowel movements have a putrid smell. With a severe form of balantidiasis, a rapid loss of body weight occurs, up to cachexia.
Chronic balantidiasis occurs with mild intoxication syndrome, frequent (up to 2-5 times a day) loose stools, flatulence, soreness of the blind and ascending intestine during palpation. Acute and continuously chronic course can lead to the development of intestinal and extra-intestinal complications: bleeding, perforation of colon ulcers, rectal prolapse, peritonitis, liver abscesses, hypochromic anemia. Without specific etiotropic treatment in the acute form of balantidiasis, the risk of death is very high. An extremely severe course of balantidiasis is noted when it is combined with helminthiasis and acute intestinal infections.
Diagnosis and treatment
Patients with suspected balantidiasis are referred to an infectious disease specialist. The disease may be suspected on the basis of positive epidemiological history and clinical manifestations; final confirmation and verification of the diagnosis is possible after endoscopic examination of the intestine and laboratory tests.
In the acute stage of balantidiasis, focal infiltrative-ulcerative changes of the intestinal wall are detected during rectoromanoscopy or colonoscopy; in the chronic course, catarrhal hemorrhagic or ulcerative lesions. Reliable evidence of balantidiasis is the presence of vegetative forms of balantidias in freshly excreted feces or in scrapings from affected areas of the intestine. The detection of cysts indicates a transient carrier of protozoal infection. During diagnosis, balantidiasis is differentiated with bacterial dysentery, amoebiasis, giardiasis, cryptosporidiosis, dysbiosis, and ulcerative colitis.
Patients with confirmed balantidiasis are subject to hospitalization in an infectious hospital. Antibacterial (monomycin, oxytetracycline, ampicillin) or antiprotozoal drugs (metronidazole, tinidazole) are prescribed as etiotropic therapy. Usually 2-3 five-day cycles of therapy are carried out. Systemic drug therapy can be supplemented with enemas with colloidal dispersed salt of norsulfazole. At the same time, detoxification therapy, vitamin therapy, and adherence to a rational diet are indicated.
Treatment of carriers of protozoal infection is also strictly mandatory. The criteria for the cure of balantidiasis are the absence of colitic syndrome, negative coprological examination on balantidiasis, and the absence of ulcerative changes in the intestinal wall.
Prognosis and prevention
Currently used methods of specific treatment of balantidiasis contribute to the recovery of patients. In the case of late or inadequate treatment, the mortality rate can reach 10-12%. Prevention of balantidiasis consists of compliance with individual safety measures (personal hygiene, boiling water, washing vegetables and fruits, etc.), as well as protection of the environment from fecal contamination (protection of reservoirs, improvement of zoohygienic conditions of pigs, neutralization of manure, etc.). Specific prevention of balantidiasis has not been developed.