Fecal nematode



The strongyloises stercoralis is a facultative parasite with alternating generations. Its self-generated generations are carried out on the ground soil, and the parasitic generations are carried out in the human body. The life history is more complicated and the disease process is long. The clinical symptoms are complex and diverse, mild asymptomatic, severe ulcerative enteritis in the small intestine and colon, and even death. When the filamentous sputum invades the skin around the anus, the local skin appears edema, tingling and itching, often accompanied by a linear or banded urticaria. It is the manifestation of perianal skin lesions of faecal roundworm disease. The domestic insect infection rate is about 10%.



A self-generation generation: males are about 0.7 x (0.04 to 0.05) mm wide and about 1.0 x (0.05 x 0.075) mm female. The eggs are similar to hookworm eggs, with a length and width of about 70 m × 40 m. In warm and humid soil, the eggs hatch rods within a few hours. The rod-shaped scorpion develops into a free-living adult through several times of molting in 1 to 2 months. The self-generation generation can be cycled multiple times. Rod-shaped mites can also develop into filiform mites after 2 times of molting, directly invading the human body through the skin, and parasitic life.

Two parasitic generations: Infected larvae (filamentous mites) invade the human body, enter the blood circulation, through the right heart to the lungs, pierce the alveolar wall capillaries, through the bronchus, pharynx to the digestive tract, and more mature and settle in the small intestine, But it is also parasitic in the large intestine and lungs. It is generally believed that there is no male parasite in the human body. The female has a length of about 2.2 mm × (0.03 to 0.075) mm. The pharyngeal tube is 1/3 or 2/5 of the body length, and the vulva is located at the posterior third of the body. Females drilled into the intestinal mucosa to lay eggs. The eggs are slightly smaller than the self-generation generation, contain larvae, hatch sweaty mites in a few hours, escape from the intestinal mucosa, and excrete with the feces. There are two developmental pathways for this rod-shaped scorpion: one is that the outer scorpion directly develops into an infectious filamentous scorpion, which accumulates on the ground soil, and waits for the skin to invade the human body to parasitize the life; the second is the rod-shaped sputum discharged with the feces. The outside world is bred into filamentous mites, but females and males that develop into self-generation generations, mating and spawning, hatching rod-shaped mites, then developing into adults, spawning, hatching rod-shaped mites, and so on, Living freely outside the camp. When the external conditions change, the rod-shaped scorpion of the self-generation generation can develop into a filamentous sputum through the skin to invade the human body, and parasitic life.

In addition, the insect has its own infection when it is parasitic. There are three types of such self-infections:

1 Direct infection in the body: After the rod-shaped sputum is released from the egg in the intestinal mucosa, the rod-shaped sputum invades the blood circulation in the intestinal mucosa and continues to develop.

2 Indirect self-infection: After the rod-shaped sputum escapes from the intestinal mucosa, it rapidly develops filamentous sputum twice in the intestine, and then invades the blood circulation from the lower part of the small intestine or colonic mucosa.

3 In vitro self-infection: After the filamentous sputum is discharged with the feces, it invades the human body from the skin around the anus.


an examination

Related inspection

Immunological examination of stool microscopy

Most of the disease has no clinical symptoms, but it can cause repeated infections due to the body's ability. When the body's resistance is low, if it suffers from various diseases, malnutrition, immunodeficiency or hormone and other immunosuppressive agents, it can often occur repeatedly. Severe self-infection, severe symptoms, and even death.

First, the perianal skin has no clinical symptoms: When the filamentous sputum invades through the skin around the anus, local skin appears edema, tingling and itching, and often accompanied by linear or banded urticaria. Since the larva migrates faster in the skin, the urticaria caused by it spreads quickly. It has been reported that a patient's urticaria spreads at a rate of 10 to 12 cm per hour. The appearance and rapid spread of urticaria in the perianal skin is often an important diagnostic basis for the migration of the larvae of the worms in the skin.

Second, intestinal symptoms and signs: the intestinal symptoms caused by roundworms are mainly long-term diarrhea, frequent diarrhea, visible watery stool or mucus bloody stool, there is urgency and heavy. Followed by abdominal pain, mostly in the right upper abdomen. Occasionally constipation. Severe infections are often accompanied by nausea, vomiting, paralytic ileus, abdominal distension, electrolyte imbalance, dehydration, and even intestinal perforation, systemic failure, and death. Some acute patients can excrete squeaky, smoky white stools and even severe fat cramps. The cause may be related to malabsorption or rupture of the intestinal lymphatic vessels, and fat entering the intestinal lumen.

Third, other symptoms and signs: This larvae can cause allergic pneumonia and asthma in the lungs, showing mild fever, cough, sputum. Chest X-ray examination has localized or diffuse inflammation shadows. The larvae develop into adults as they stay in the lungs, and the larvae sometimes invade the chest and cause pleurisy. In addition, the metabolic products of the worm and the death disintegration products can also cause symptoms of systemic poisoning, such as fever, anemia and neurological symptoms such as irritability and insomnia. Acute infection can cause eosinophilia, often up to 15% to 85%.


Differential diagnosis

Itchy skin: Itchy skin refers to a skin disease that has no primary rash but is itchy. It is a neuropsychiatric skin disease and is a cutaneous neurosis disorder. Clinically, only those with itchy skin and no primary skin lesions are called pruritus. It belongs to the category of "itchy wind" of Chinese medicine. Itchy skin is divided into common and allergic types. It can occur all over the body, especially in the face, back and limbs. Ordinary skin itching is generally caused by too dry skin. It can be taken orally with cod liver oil pills, multivitamin tablets, etc. Western medicine must be diagnosed and guided by a professional doctor. Do not blindly use drugs, especially those containing hormones.

Skin flushing plaque like urticaria: Gastric carcinoids may cause urticaria-like skin flushing plaques due to possible secretion of histamine. Carcinoids, also known as carcinoid tumors, are a group of The clinical, histochemical and biochemical characteristics of new organisms in the gastrointestinal tract and other organs of chromaffin cells may vary depending on where they occur. Such tumors can secrete biological active factors such as serotonin (serotonin), kinins, histamine, etc., causing vasomotor dysfunction, gastrointestinal symptoms, heart and lung lesions, etc., called carcinoid syndrome. ).

Was this article helpful?

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.