Balantidiasis

　　One, etiology

　　The colonic acanthamoeba was first discovered by Malmsten in 1857 in the feces of 2 patients with acute dysentery. Subsequently, LeuKart found the same worm in the large intestine of pigs in 1861. In 1862, Stein classified it into the genus Balantidium and named it Balantidium coli, its taxonomic status is Protozoa Subkingdom, Ciliate Phylum, Kinetoplastida Class, Parabasalia Subclass, Trichomonadida Order, Trichomonadida Suborder, Balantidium Genus, Balantidium coli.

　　1. The colonic acanthamoeba is the only ciliate discovered to be parasitic in humans and also the largest protozoan parasitic in humans. Its life cycle includes two basic forms: the trophozoite and the cyst.

　　(1) The trophozoite is circular or oval, colorless, transparent, or faintly gray with a green tinge, with a size of about (30～200) μm × (25～120) μm. The ventral surface is slightly flattened, and the dorsal surface is elevated. The surface of the organism has ridge-like elevations and groove-like depressions, extending from the anterior to the posterior end. The surface of the ridge-like elevations has folds, and the groove-like depressions are located between the two ridges. The surface纤毛 all extend outward from the grooves, and the movement of the flagella can cause the organism to move forward and backward. The surface of the organism is covered with a pellicle, below which is the transparent ectoplasm, and inside is the endoplasm. The anterior end of the organism is slightly pointed, with a food vacuole formed by the invagination of the pellicle on the ventral surface. Food is digested within the vacuole, and the residual substances are excreted out of the body through a small and not obvious triangular anal pore at the posterior end of the organism. The trophozoite has electron-dense bodies. There are also two contractile vacuoles in the cytoplasm that can regulate osmotic pressure. The cytoplasm also contains polysaccharide granules, food vacuoles, and so on. Mitochondria are distributed around the periphery of the organism.

　　(2) The cyst is round or oval, about 40-60μm in size. The cyst wall is thick and transparent, light yellow or light green. Active trophozoites can be seen in fresh cysts. The cyst has strong resistance to the external environment and can survive for 2 weeks to 2 months at room temperature, and it will die after 3 hours in direct sunlight; it also has strong resistance to chemical drugs and can survive for 4 hours in a 10% formalin solution.

　　2. The cyst is the infective stage of this worm. Humans become infected by eating food or drinking water contaminated with cysts. The cyst is digested by digestive juices in the digestive tract, and the worm escapes from the cyst to become a trophozoite. The trophozoite falls into the large intestine and feeds on intestinal waste, intestinal wall cells, and bacteria. The trophozoite reproduces mainly by transverse binary fission in the intestine, but can also reproduce by budding. Some trophozoites are affected by desiccation during the formation of feces, and the worm becomes round, secreting a cyst wall to enclose the worm, forming a cyst and excreted with feces. Trophozoites in the pig intestinal lumen can form a large number of cysts, but it is rare in the human intestinal lumen. In addition, the nucleus does not divide during cyst formation, so when the cyst is excreted from the digestive tract, only one trophozoite can be produced from a single cyst.

　　2. Pathogenesis

　　Most people believe that the colon bag mucus has pathogenicity. When the human body has chronic diseases, malnutrition, and intestinal dysfunction, the worm can invade and reproduce to cause disease. After the worm invades the human body, it needs a period of time to adapt to the intestinal symbiotic flora. Once adapted, it can reproduce rapidly in large numbers. Some bacteria in the intestines, such as Klebsiella, Staphylococcus aureus, and Enterobacter, as well as other parasites, have the effect of promoting the growth of this worm and causing pathological changes. The colon bag mucus invades the intestinal tissue must rely on the mechanical movement of the worm's cilia and the action of hyaluronidase secreted. The worm dissolves the intercellular matrix with hyaluronidase and penetrates the intestinal tissue. In severely infected pig feces, glycogen phosphorylase and hemolysin have also been isolated. The worm uses the above factors to cause colonic mucosal inflammation, necrosis, and ulcers, and can also secondary bacterial infection, thereby aggravating mucosal lesions. The pathological changes are similar to those caused by intracellular amebae. The lesions are mainly located in the cecum and sigmoid colon, occasionally involving the distal ileum and appendix, and in some cases, the worm can invade mesenteric lymph nodes, liver, lung, pleura, urinary and reproductive tract, etc. The intestinal mucosa is congested and edematous, and sometimes there are pinpoint bleeding spots. In the early stage of the lesion, the intestinal mucosa may have volcanic crater-like ulcers with a diameter of a few millimeters, which gradually expand and fuse to form ulcers with small openings, large bases, and irregular edges. Unlike amebic ulcers, the ulcers formed by this disease have slightly larger openings and short, thick necks. The bottom of the ulcer is generally located in the submucosa, but a large number of trophozoites can also be seen in the surrounding intestinal mucosa. The mucosa between the ulcers can be normal or edematous and hemorrhagic, and there are also lymphocytes and eosinophils infiltrating.

　　1, Appendicitis:It refers to the inflammatory changes of the appendix due to various factors. It is a common disease, and its prognosis depends on whether it is diagnosed and treated in time. Early diagnosis and treatment can lead to recovery within a short period of time, with a very low mortality rate (0.1% - 0.2%); if diagnosis and treatment are delayed, it can cause serious complications, even leading to death. Appendicitis is a common disease. Clinically, it often presents with right lower abdominal pain, fever, vomiting, and increased neutrophils. Appendicitis is inflammation of the appendix, the most common abdominal surgical disease.

　　2. Intestinal perforation:It is the process of intestinal contents溢入peritoneal cavity due to intestinal rupture. Intestinal perforation refers to the process of intestinal contents溢出 into the peritoneal cavity due to the penetration of intestinal lesions through the intestinal wall, which is one of the serious complications of many intestinal diseases. It causes severe diffuse peritonitis, mainly manifested by severe abdominal pain, abdominal distension, and peritonitis symptoms and signs. In severe cases, it can lead to shock and death.

　　3. Peritonitis:The main clinical manifestations of acute peritonitis are early peritoneal irritation symptoms such as (abdominal pain, tenderness, muscular tension, and rebound pain), and later, due to infection and absorption of toxins, the main manifestations are systemic infection and toxic symptoms.

　　Most people do not have symptoms after infection with Trichomonas colona, and only less than 1/5 of those infected develop symptoms. Clinical manifestations can be divided into acute and chronic types.

　　1. Acute type:The onset is acute, with marked diarrhea, several to more than ten times a day, and in severe cases, up to dozens of times. Stools may contain mucus or pus and blood, but there is usually no smell of amebic dysentery. Abdominal pain is common, accompanied by tenesmus, tenderness around the umbilicus or in the lower abdomen. Patients often have irregular fever, nausea and vomiting, fatigue, and decreased appetite. Severe cases can lead to dehydration, malnutrition, and weight loss, and occasionally can cause intestinal perforation. This type has a short course and often resolves spontaneously without treatment.

　　2. Chronic type:The onset is insidious, mainly manifested by recurrent diarrhea, which can last for several months to several years and呈周期性发作 periodic attacks. It is often triggered by fatigue, catching a cold, drinking alcohol, or eating fatty foods. Stools are passed several times a day, mostly paste-like or watery, with mucus but rarely pus and blood. A few patients may have alternating diarrhea and constipation, accompanied by abdominal distension, intermittent abdominal pain, active bowel sounds, and tenderness in the lower abdomen. Long-standing cases may have weight loss, anemia, weight loss, irritability, insomnia, and other symptoms.

　　This disease is transmitted through the oral route, so it is emphasized that attention should be paid to dietary and personal hygiene, strengthened management of human and pig feces, to avoid contamination of food and water sources with pig feces, and actively treating sick pigs. The cysts of Trichomonas colona have strong resistance to the external environment, can survive for 2 weeks at room temperature, 2-3 months in a humid environment, and can also survive for 4 hours in a 10% formaldehyde solution. Therefore, the harmless treatment of feces from patients or sick pigs is particularly important for controlling the spread of the disease.

　　1. Blood count

　　Most patients have normal blood counts, and in patients with acute illness complicated by bacterial infection, the white blood cell count may increase slightly to moderately. In patients with chronic illness, there may be varying degrees of decrease in red blood cell count and hemoglobin.

　　2. Pathogen examination

　　The detection of Trichomonas colitis in the diarrhea is an important basis for diagnosis. Generally, it should be checked directly from the fresh feces of the patient by smearing. Within 6 hours after the feces are excreted, the trophozoite can still maintain activity, and if it is too long, the activity will disappear and affect observation. Since Trichomonas colitis rarely forms cysts in the human intestine, it should mainly be searched for trophozoites in the feces. However, cysts may also be found in the feces of a few constipated patients. The excretion of worms in the feces is often intermittent, and it should be checked repeatedly. When checking, attention should be paid to picking the mucus part and directly smearing it with physiological saline for observation. If necessary, iron hematoxylin staining can be performed. Trichomonas colitis should be distinguished from the trophozoites of Entamoeba histolytica, animal ciliates, and other free-living ciliates. The distinguishing feature is that this worm is larger, elliptical, with a longitudinal cleft in the mouth and nucleus at the front. If the repeated fecal examination still fails to find it, material can be scraped from the edge of the ulcer of the sigmoid colon by sigmoidoscopy or pathological examination can be performed on the lesion tissue, and trophozoites can often be found.

　　1. Pay attention to eating more fresh vegetables and fruits appropriately, consume sufficient high-quality protein and vitamin-rich foods, and pay attention to drinking more water.

　　2. Avoid overeating and drinking, avoid eating spicy and刺激性 food, avoid smoking and drinking, in order to avoid stimulating the gastrointestinal tract and aggravating the disease.

　　3. Pay attention to dietary and personal hygiene, strengthen the management of human and pig feces, avoid the pollution of food and water sources by pig feces, and actively treat sick pigs.

　　I. Treatment

　　The general treatment principle is the same as that for other intestinal infectious diseases. The first choice for pathogen treatment is metronidazole, which can achieve satisfactory efficacy. The dosage for adults is 0.4-0.6g per time, 3 times a day, taken orally, for 5-10 consecutive days. Metronidazole can cause the rupture of the body membrane of the worm, nuclear disintegration until disappearance. Generally, after 24-72 hours of taking the medicine, the worm in the feces will disappear, and the symptoms will gradually improve. At the end of the course of treatment, the efficacy can reach 90%-100%. Other drugs such as tetracycline, quinacrine, paromomycin, etc., can also be chosen, but their efficacy is not as good as that of metronidazole.

　　II. Prognosis

　　The course of this type of disease is usually short and often cannot be cured spontaneously.