Cryptosporidiosis

Introduction to cryptosporidiosis Cryptosporidium is caused by an infectious disease called Cryptosporidium parvum, and other species of Cryptosporidium occasionally cause the disease. Symptoms usually appear about 7 days after infection, including abdominal pain, watery diarrhea, vomiting and fever. Most patients have symptoms lasting 6 to 10 days, but may last for several weeks. Patients with problems with the immune system, such as infections, can be very serious or even life-threatening. Since the official report in 1976, it has been found that the disease is widespread and is a common pathogen of diarrhea among tourists. AIDS patients have many diseases. basic knowledge Sickness ratio: 0.002%-0.004% Susceptible people: no specific population Mode of infection: digestive tract spread Complications: reactive arthritis cholecystitis dehydration electrolyte disorder

The cause of cryptosporidiosis

(1) Causes of the disease

Cryptosporidium is an obligate intracellular growth parasitic protozoa belonging to the genus Sporozoite, Coccidia, Coccidioides, Eimeria, Cryptosporidium, Cryptosporidium, and worms. Spherical, 2 ~ 4m in diameter, its life history is similar to other protozoa of the sporozoites, including asexual genital mutilation, sexual reproduction and spore reproduction, all of which are carried out in the same host, and their oocysts are oval The diameter is 2-6 m, the wall of the oocyst is smooth, and there are 4 crescent-shaped sporozoites in the mature oocyst. When they are swallowed by human or animal, they are decapsulated in the small intestine, and the sporozoites escape from the fissure of the oocyst wall. The microvilli brush attached to the epithelial cells of the small intestine is inserted into the vaccination of the worm to develop into a trophozoite for schizogulation, first developed into a trophozoite containing 8 small nuclei, and then further developed into 8 cracks. After the cleavage of the type I schizont, the merozoites invade other small intestinal epithelial cells and continue to develop type I schizophrenia or develop into type II schizonts with only 4 merozoites. The merozoites released by mature type II schizonts develop separately Female (big), male (small) gametophytes, respectively, and produce male and female gametes, and finally for the male and female gametes zygote develops into oocysts.

There are two kinds of oocysts: thin wall and thick wall. The former accounts for about 20%, and the resistance to the external environment is weak. After the sporozoites escape, they directly invade the new host cells to continue schizogulation, resulting in repeated infection in the host. The thick-walled oocyst is sporulated in the host body, and the wall of the capsule is double-layered. It has strong resistance to the external environment and is infected by the excretion of the feces. It can be inactivated by 10% formaldehyde solution or 5% ammonia water, after 65 °C. At 30 minutes, the infectivity of the oocysts can also be lost.

At present, there are at least 6 species of Cryptosporidium that have been found. The human and mammalian Cryptosporidium infections are almost caused by Cryptosporidium parvum, but domestic Zuo Yangxian reported that they have been from a small 33-day-old. Cryptosporidium parvum and Cryptosporidium oocysts were also found in cattle feces.

(two) pathogenesis

The exact pathogenesis of this disease is still not very clear. Most people think that it may be due to extensive damage of intestinal mucosal epithelial cells and atrophy of the villi. As a result, it is speculated that Cryptosporidium parvum may produce enterotoxin, and they found that the infection is tiny. The spore-like burdock fecal supernatant has enterotoxin-like activity. The loss of water and electrolyte in the course of the disease is caused by damage of intestinal mucosa and intestinal dysfunction. In addition, the loss and decrease of disaccharidase and other mucosal enzymes in the intestinal tract are observed. It is also one of the causes of diarrhea. It has been found that prostaglandin E2 derived from intestinal epithelial cells infected with Cryptosporidium parvum has an effect of stimulating Cl-active secretion and inhibiting neutral NaCl absorption.

The pathological changes caused by Cryptosporidium in humans and animals are basically similar. The lesions are mainly found in the small intestine and colon, and the stomach and esophagus can also be involved. The villus atrophy in the small intestine lesions becomes shorter or even disappears, and the crypt epithelial cells proliferate and crypt. Significantly deepened, the epithelial cells on the surface of the mucosa were short columnar, and the nucleus was irregularly arranged. Mononuclear cells and multinuclear inflammatory cells were observed in the villus epithelial layer and lamina propria. The pathological changes of the colonic mucosa were similar to those of the small intestine. The above lesions can return to normal. When the infection extends to the gallbladder, it can cause acute and necrotizing cholecystitis. The gallbladder wall is thickened and hardened, the mucosal surface is flattened and ulcers can appear, and the gallbladder wall necrosis is accompanied by multinucleated cell infiltration. Active bronchitis and focal interstitial pneumonia can be seen in lung biopsy specimens of patients with Cryptosporidium infection in the lung.

Cryptosporidium prevention

The feces of patients and sick animals should be strengthened to prevent feces from contaminating food and drinking water. Pay attention to personal hygiene. The oocysts are strong in the outside world. Common disinfectants cannot kill them. 10% fumarin, heated 65~70°C 30 minutes to kill oocysts, patients with used colonoscopy and other equipment, potty, etc., immersed in 3% bleaching powder clarification solution for 15 minutes before cleaning, patients should be properly isolated, pay attention to personal hygiene, do a good job of personal protection.

Cryptosporidiosis complications Complications Reactive arthritis cholecystitis dehydration electrolyte disorder

Can be complicated by cholecystitis and pulmonary infection, occasionally reactive arthritis; infants and young children may have dehydration, electrolyte imbalance.

Symptoms of cryptosporidiosis common symptoms upper abdominal discomfort nausea diarrhea hypokalemia abdominal pain bacterial infection vitamin deficiency watery dehydration

The incubation period is 4 to 14 days.

1. Acute gastroenteritis type of immune function of normal infections are mostly acute gastroenteritis, diarrhea, 4 to 10 times a day, mushy or watery, occasionally a small amount of pus, may have stench, often accompanied by the upper abdomen Discomfort, pain, and even nausea, vomiting, partial fever, self-limiting course, more natural relief within 2 weeks, no recurrence, good prognosis.

2. Chronic diarrhea is mainly seen in people with impaired immune function, especially AIDS patients. The onset is slow, the diarrhea is delayed, the watery stool is more, the amount is more than 1 to 10 liters per day, about 10 times a day, occasionally bloody. However, more with abdominal pain, prone to dehydration, acidosis and hypokalemia, vitamin deficiency, etc., the course of disease can last 3 to 4 months or even more than 1 year, can be repeated.

According to epidemiological data, clinical manifestations and laboratory tests to confirm the diagnosis, any disease causing acute and chronic diarrhea should be identified, especially bacterial infectious gastroenteritis.

Examination of cryptosporidiosis

1. Fecal examination of fecal microscopic examination of white blood cells or pus cells, but no red blood cells, few phagocytic cells, oocysts found in the feces, generally by gold amine-phenol staining method for screening, suspected insects can be improved acid-fast staining The combination of the two is the most effective.

2. Pathogen examination collects feces or vomit in patients, and the detection of Cryptosporidium oocysts is the main detection method. It can be detected by direct smear or concentration method and special staining.

3. Immunological examination The specific antibody was detected by enzyme-linked immunosorbent assay. The IgM antibody appeared early, but disappeared quickly and was not easy to detect. The IgG antibody appeared about two months after infection, which lasted for more than 1 year and was suitable for epidemics. The investigation, immunofluorescence assay (IFA) and monoclonal antibody assays have a sensitivity and specificity of 100%.

4. Small intestinal mucosal biopsy can be used if necessary.

Diagnosis and identification of cryptosporidiosis

Attention should be paid to the identification of cholera, viral gastroenteritis, bacterial dysentery and intestinal amoeba.

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