Strongyloidiasis

　　Strongyloides stercoralis was first detected by Normand (1876) from the feces of a French soldier suffering from chronic diarrhea in Vietnam, and was named Anguillulastercoralis. After careful research by many scholars, the morphology, ecology, and pathogenicity of Strongyloides stercoralis have been clarified.

　　1. Morphology of Strongyloides stercoralis: dividedTwo life stages, the parasitic stage (parasitic stage) and the free-living stage (auto-living stage), with only females in the parasitic stage and both male and female in the free-living stage.

　　The parasitic female (parasitic female) is 2.2～2.5mm long, 0.03～0.05mm wide, with a funnel-shaped mouth, a cylindrical long esophagus (occupying 1/3～2/5 of the body length), a pointed tail end, the anus located on the anterior ventral surface, the vulva located at the middle and posterior 1/3 of the body length on the ventral surface. There are ovaries, oviducts, uterus, vagina, and vulva in the body. The eggshell is thin and transparent, and after being laid, it is 70μm × 43μm, which can quickly develop into larvae and hatch (5～6h). Except for those with severe diarrhea or those taking purgatives, it is usually not easy to find eggs in feces.

　　The free-living male and female adults are smaller than the parasitic female, and the esophagus is also shorter, showing a double-spherical shape. The male worm is 0.7mm × (0.035～0.05)mm, with two brown copulatory spines and a connecting band. The female worm is 1.0mm × 0.05mm, with a pointed tail, the vulva opening at the middle of the body, and the eggs are similar to those during the parasitic stage.

　　2. Life history of parasitic femaleIt mainly parasitizes in the small intestine (especially the duodenum), and occasionally also in the large intestine, bile duct, pancreatic duct, lung, urinary tract, esophagus, and other places. It lays eggs deeply in the mucosa, hatches quickly into a filariform larva and enters the intestinal lumen. This larva develops and grows in the intestinal lumen, and is excreted with feces. It develops in the soil, molts (molt) into infective filariform larvae, which enter the human body through the skin or mucosa at an appropriate opportunity, enter the blood flow to the lungs, pass through the trachea, pharynx, esophagus, and stomach to enter the intestines, and develop into female worms in the mucosa (with a cycle of about 17 days in the human body). Some filariform larvae become filariform larvae before being excreted from the human body, directly invade the intestinal mucosa or anal skin to cause self-infection. If the filariform larvae during the parasitic stage reach the outside world and do not develop into filariform larvae but into free-living female and male worms, they participate in the free-living life cycle. The free-living female and male adults mate and lay eggs, hatch into filariform larvae, and then molt into adults, continuing to live a free-living life. Under unfavorable conditions, they can become filariform larvae and infect humans, entering the parasitic stage.

　　The complications of Strongyloidiasis mainly occur in severe patients, and complications are often the cause of death, such as shock, respiratory failure, bronchopneumonia, sepsis, etc., with a mortality rate of about 26%, reaching 50%-86% in patients with disseminated systemic infection.

　　About 2/3 of cyclosporiasis infection patients are asymptomatic. It has been reported that some patients have been infected with this worm for 40 years without symptoms, and the clinical manifestations of this disease can vary in severity.

　　1. Larval migration symptoms

　　It is the most common early manifestation, with 66-84% of patients developing macules or papules around the buttocks, anus, or other infected sites, about 5% of patients have cough, asthma, low fever, or allergic pneumonia due to pulmonary infiltration, and only a few patients may have severe respiratory symptoms such as dyspnea, cyanosis, hemoptysis, and concurrent bacterial bronchopneumonia.

　　2. Gastrointestinal symptoms

　　Moderate and severe patients often have abdominal pain, diarrhea, vomiting, anorexia, or constipation. The location of abdominal pain varies, usually a burning sensation or colic in the upper abdomen, sometimes confused with peptic ulcer disease or acute abdomen. Diarrhea is usually watery or loose, and may appear with bloody mucous diarrhea. Some may develop paralytic ileus, abdominal distension, electrolyte imbalance, dehydration, and circulatory failure.

　　3. Other

　　Different symptoms appear with the invasion of different organs, such as meningitis, urinary tract infection, etc. Some patients may experience fever, malaise, irritability, depression, insomnia, and other symptoms of neurasthenia due to the metabolic products or disintegration of the worms. Some may have concurrent bacterial or fungal sepsis. When patients are immunocompromised, such as in AIDS patients, cyclosporiasis can cause disseminated infection throughout the body, leading to multiple organ failure or death.

　　Cyclosporiasis is similar to hookworm disease, and proper fecal disinfection and individual skin protection should be done. Patients should be treated thoroughly to avoid repeated self-infection.

　　Some scholars have obtained protective IgG antibodies, laying an experimental foundation for the preparation of specific immunization vaccines.

　　Cyclosporiasis can be diagnosed by the following tests:

　　First, blood routine examination

　　In acute infections with increased white blood cells and eosinophils, white blood cells can reach (8-30) × 10^9/L, and the ratio of eosinophils is usually between 0.25-0.35, occasionally up to 0.85. After the acute stage, it returns to normal. In severe infections, eosinophils can be normal or decreased, indicating poor prognosis.

　　Second, fecal pathogen examination

　　Larvae eggs may be found in patients with diarrhea, but mainly larvae are searched. However, due to the small amount of larvae and the lack of regularity in their excretion, the rate of missed diagnosis can be as high as 70% using routine fecal detection methods. Methods for detecting larvae in feces include:

　　1. Direct smear to find larvae.

　　2. Aldehyde ether centrifugation method.

　　3. Baermann funnel separation method: Take a piece of circular copper wire mesh, fold the four sides into a basket shape, line the bottom with two layers of gauze, place it in a funnel with a diameter of 15 cm, connect a controllable rubber tube to the outlet of the funnel, place an appropriate amount of patient's feces on the above gauze layer, add an appropriate amount of 40-46°C warm water to moisten the feces, the larvae can then move to the water and concentrate at the bottom of the funnel, and the liquid can be collected and examined under a microscope after several hours.

　　4、琼脂板孵育法，粪便中幼虫检出率可达96.8％，并可在琼脂板上发现特有的幼虫行迹现象，也可采集十二指肠液镜检查找幼虫。

　　4. Agar plate incubation method, the detection rate of larvae in feces can reach 96.8%, and unique larval movement phenomena can be found on the agar plate, and duodenal fluid can also be collected for microscopic examination to find larvae.

Third, pathogen serological examination

　　More than half of the patients have elevated serum IgE levels, but the specific IgE levels of patients with disseminated infection are significantly lower than those of non-disseminated infection patients, about 90% of the patients have IgG and IgE antibodies against the filarial antigen in the serum. The US CDC used enzyme-linked immunosorbent assay (ELISA) to detect 76 patients diagnosed with larvae in feces, with a sensitivity of 94.6%.

　　Fourth, adult worm antigen intradermal test and indirect fluorescence test can assist in diagnosis.

　　Dietary taboos for strongyloidiasis patients

　　The diet of strongyloidiasis patients should be light and easy to digest, eat more fruits and vegetables, reasonably match the diet, and pay attention to adequate nutrition. In addition, patients should also pay attention to avoid spicy, greasy, cold food. Patients should also pay attention to the following aspects of diet:

　　1. Drink more boiled water.

　　2. Eat cooked food.

　　Conventional methods of Western medicine for the treatment of strongyloidiasis

　　Through the treatment of anthelmintic drugs, the efficacy of strongyloidiasis is relatively good, including the following:

　　1. Fenbendazole 100mg per dose, twice a day, for a total of 4 days.

　　2. Albendazole 400mg, taken all at once, for a total of 3 days or 14-15mg/(kg·d), 5-7 days therapy, cure rate 68-86%.

　　3. Ivermectin has good therapeutic effect, strong tolerance of patients, and is expected to be used as the first-line drug for antiparasitic roundworm infection.

　　5. For severe patients with complex conditions, in addition to antiparasitic drugs, actively adopt symptomatic and supportive therapies, such as anti-shock, correction of dehydration and electrolyte disorder, control of secondary infection, etc.