Anisakiasis

Introduction to anisakisis Anisakiasis is a disease caused by parasitic worms of the third larvae of the genus Heterodera, which is caused by raw sea carp containing live larvae. The disease is more common in Japan, Europe and the United States, and there are no case reports in the country, but the third-stage larvae infection rate of the fish in the southeast coast is high. Acute clinical manifestations include nausea, vomiting, severe abdominal pain and other gastrointestinal symptoms with eosinophils; chronic phase characterized by gastric or intestinal eosinophilic granuloma, which can be complicated by intestinal obstruction, intestinal perforation and peritonitis. basic knowledge The proportion of illness: 0.0003%-0.0004% Susceptible people: no special people Mode of infection: fecal mouth spread Complications: intestinal obstruction peritonitis

Etiology of anisakisis

Infection (30%):

Anisakis is a member of the order Aphididae, Aphisidae, and Aphididae. It is known that at least 30 species of Anisakidae are known, because the identification of larvae is difficult and it is easy to cause synonymousness. There are four main genera of pathogenic species: 1 Anisakis, including A. simplex, A. typica, and A. physeteris. ; 2 Pseudoterranova, including P. decipiens, Phocanema, terraline (Terranova); 3 pairs of Contraceacum; 4 genus Hysterothylacium), including nematodes (Thynnascaris), etc., has been found in the fishes of China's seas, such as simple nematodes, pseudo-nematodes or parasitic nematodes, but no reports of human infections, and the anisaki adults are shaped like aphids, males. The length of the worm is 31-90 mm; the female is 63-100 mm. The adult is parasitic in the stomach of whales, dolphins, seals, sea lions and other marine mammals. The size of the eggs is 50.7 m × 53 m, discharged into the seawater with the host feces, fertilized. After the egg cells develop, they form embryos and become the first phase. At the maturity of the larva, when the seawater temperature is suitable (about 10 °C), the larvae of the egg are shelled out and develop into the second stage larvae, which is about 230 m long and can swim freely in seawater and survive for 2 to 3 months. When the second stage larva is swallowed by crustaceans (first intermediate host) such as krill in seawater, it penetrates into the body cavity and develops into a third stage larva in its blood cavity, when marine fish and mollusks (the first Two intermediate hosts) After ingesting the larvae containing crustaceans, the larvae penetrate the digestive tract and its internal organs and muscle tissue. The marine fish containing the third larvae are swallowed by marine mammals (final host) and the larvae penetrate into their stomachs. The mucosa grows in groups, develops into females, male adults, mates and lays eggs, completes their life history, and humans are not suitable hosts for A. elegans. The third larvae can parasitize various parts of the human digestive tract and can also cause visceral larvae to migrate. Symptoms, but this larva cannot develop into an adult in the human body and usually dies within 2 to 3 weeks.

The third-stage larvae of the genus Anisitas often migrate from the intestine to various tissues in the fish, and the abdominal cavity is more. When the fish dies, the larva migrates to the body wall muscle, and the third larvae form in the fish body. Slender, about 30mm × 1mm in size, with side cables, Y-shaped in cross-section, three lips around the mouth (one on the back, two on the ventral side) and one drill tooth. The esophagus is white and can be divided into muscles. Glandular gastric sac at the anterior and posterior, and connected to the intestine, the anus is at the end, the drain hole is at the level of the abdominal nerve ring, behind the drill, the sexual organs are obvious, the fish in the East China Sea, the Yellow Sea and the Beibu Gulf The simple third-stage larvae of A. elegans, the size is about 18.73mm × 0.14mm, the esophageal length is 2.29mm, and the tail length is 0.09mm. Japanese scholars are characterized by their body length, width and stomach and tail shape. According to the experimental study on the resistance of larvae to I, II and III, the larvae of larvae showed that 3%~15% sodium chloride solution could not kill quickly, and could survive 96-233h; 38-degree liquor Survival 2.5 ~ 48h; 60 ° white liquor survived 0.2 ~ 2.2h 15% vinegar survived 17.6-75.3h; 30% vinegar survived for 1~3h; garlic juice survived for 5.5-6h; soy sauce and pepper juice survived for 29.8h and 154.6h respectively, and the larvae of the larvae in the carp It survived at -18 °C for 48 hours, died at -20 °C for 2 hours, and survived at 2 °C for 50 days. Live larvae were found in frozen fish imported from North Korea and the former Soviet Union. Large fish were frozen in the deep muscles. The larvae do not necessarily freeze to death, and the larvae can be killed by heating to 60 °C.

Route of infection (30%):

The third stage larvae of the anisakis invade the human body through the mouth. The larvae have strong spurting force and can penetrate into the throat, causing lesions in the stomach or intestinal mucosa. The symptoms are mild when the initial infection is not easy to find, and the body is caused by repeated infections. Sensitive, it causes a heavier reaction, the larva drills into the gastrointestinal mucosa, ingests tissue components, causes an inflammatory reaction, characterized by eosinophil infiltration, if the larva continues to deepen, it can reach mucosal edema, hemorrhage, connective tissue Hyperplasia, thickening, with lymphatic vessel dilatation and lymphangitis, common larvae in the center of the lesion, a few days later, eosinophilic abscess appeared around the worm, then the worm died, decomposed, gradually formed eosinophilic granuloma, can cause intestinal obstruction, Intestinal necrosis, severe cases even penetrate the intestinal wall, larva invades the abdominal cavity and then migrates to the mesentery, liver, pancreas, abdominal wall, groin and oral mucosa. From the surgically removed pathological tissue specimens of the stomach or intestine, there are localized masses under the mucosa. Bleeding, erosion and ulceration, thickening of the intestinal wall, up to two or three times normal, is the cause of intestinal stenosis and intestinal obstruction.

Pathology (30%):

Pathological sections can be seen in the submucosal layer with one or several pieces of worm body. Most of the worm body is curled due to intrusion into the layer. Sometimes there are residual worm fragments or necrotic tissue in the center of the lesion, or only the worm body is left due to the production. There are a large number of eosinophils, plasma cells and macrophages infiltration around the horns or voids. According to the degree of pathological damage, Kojima (1966) classifies the pathological images into four types: type I foreign body honeycomb. Type II abscess type; type III abscess granuloma type; type IV granuloma type, from the onset of the disease, the lesions migrated from type I to IV, type I and type II are exudative inflammatory phase, visible stomach, intestine Wall height edema; type III and type IV belong to the proliferative inflammatory phase, and granuloma consisting of epithelial cells and the like can be seen around the abscess.

Anisycosis prevention

The disease should be mainly prevention. Do not eat raw sea fish fillets or semi-cooked fish fillets. Fish meat should be cooked before being eaten. All kinds of marine fish should be frozen at -20 °C for 24 hours before they can be marketed, and the sanitary inspection of imported fish should be strengthened.

Heterosis Complications, intestinal obstruction, peritonitis

Can be complicated by intestinal obstruction, intestinal perforation and peritonitis.

Symptoms of ectopic nematode common symptoms abdominal pain upper abdominal pain diarrhea nausea bloating low heat mucus fecal granulomatous intestinal perforation

Symptoms are closely related to the number of infected insects, parasites and duration. The larvae of the echinococcosis can be parasitic in the throat, stomach and intestinal mucosa, but the stomach is the most common, about twice the size of the intestine. Nematode disease is the most (97.3%).

The incubation period is generally 2 to 20 hours. According to Japanese reports, the shortest time from eating sashimi to the onset is 30 minutes, the longest is 168h, 64% within 3 to 8 hours, and 88% within 12 hours. Intestinal nematode disease The incubation period is longer, usually 1 to 5 days after eating the fish fillets. The clinical symptoms and signs can be described as follows:

Gastric echinococcosis

It can be divided into acute type and chronic type. The former is Arthus type allergic inflammation caused by reinfection; the latter is a localized allergic reaction caused by primary infection. The larvae are parasitic in the stomach and stomach and account for 85%. Above, the clinical manifestations of upper abdominal pain or cramps, repeated attacks, often accompanied by nausea, vomiting; a few have lower abdominal pain, occasional diarrhea, 70% of patients with stool occult blood positive, peripheral blood eosinophils increased significantly, stomach X-ray meal 150 cases were examined, including gastric angle widening, antrum stiffness, 68 cases of stenosis or gastric peristalsis, and 16 cases of filling defect-like changes. The softness of gastric edema and compression and gastric mucosal wrinkles According to the judgment of the large, 70 cases of filling defects and thick wrinkles were seen in the stomach, 34 cases of gastric edema and mucosal folds and obvious deformation of the stomach, and 113 cases of X-ray examination showed worms, gastroscope 150 For example, except for the cardia, the worm body is drilled, with the stomach angle and the stomach body being more, the local visible unevenness is slightly raised, and the wrinkles are swollen; the gastric mucosa at the worm body is slightly infiltrated. 38 cases of blood and erosion, 150 cases of examination There were 151 outbreaks of worms, which were all third-stage larvae of A. elegans. Among them, 1 case was detected in 3 cases, 3 cases in 2 cases, and 1 in each case.

2. Intestinal nematode disease

The ratio of male to female is about 1.8:1. The patients are mainly from 10 to 39 years old. The lesions include duodenum, jejunum, ileum, cecum, appendix and rectum. They often have severe abdominal pain within 1 to 5 days after eating sashimi. Nausea, vomiting, bloating, low fever, followed by diarrhea, tar-like mucus, tenderness in the right lower abdomen and umbilical cord, sometimes accompanied by urticaria, patients often suffer from intestinal perforation, peritonitis or localized intestinal necrosis. The larva was found in the diseased tissue and confirmed.

3. Esophageal nematode disease

Japan has reported a case of a 77-year-old female patient who felt pain in the heart after eating sashimi for 1 day before the onset of illness. She felt tingling under the sternum at midnight, suffocating her breath, and went to the hospital the next morning. She immediately underwent fiber endoscopy and found in the lower esophagus. White worms were removed with forceps and identified as genus larvae.

The eclipse larvae directly penetrate into the mucosa of the throat when eating raw sea fish fillets, causing itching, nausea or coughing of the throat. It is often coughed or vomited from the sputum. Cases reported in the US East and West Coast in recent years. More, sometimes with a laryngoscopy, you can find the worm body, commonly used to remove the symptoms and relieve the symptoms.

4. Extraintestinal ecchymosis

The larva can penetrate the intestinal wall into the abdominal cavity and then migrate to the liver, pancreas, omentum, mesentery, ovary, abdominal wall subcutaneous, groin or oral mucosa, causing peritonitis, eosinophilic granuloma and subcutaneous mass, often misdiagnosed as Malignant tumor.

Inspection of echinococcosis

Immunological examination

The anti-intradermal test of the larvae of the larvae was positive for the intradermal test. The serum specific IgE was elevated, and the latex agglutination test and the indirect fluorescent antibody test were positive.

2. Histopathological examination

In the pathological examination of surgically resected specimens, the lesions of the worms, horns or muscle layers of the worms can be seen in the lesions of cellulitis, abscess, abscess granuloma and granuloma.

3. Molecular biology technical inspection

Recently, based on the simple eclipse, the ribosomal DNA fragments of C. elegans and C. elegans were different, and the restriction fragment length polymorphism (PCR-RFLP) and single-stranded configuration based on polymerase chain reaction were established. The state (SSCP) method can be used to diagnose ischaegosis in humans and animals.

4. Gastroscopic examination

The larvae and histopathological examination found that the cross-section of the worm can be confirmed. The gastroscopic examination showed that the mucus of the whole gastric mucosa increased, and the folds were swollen. Among them, the live larvae with white transparent head drilled into the gastric mucosa showed spiral or S-shaped curl. The mucosa around the body is erosive, with clots, bleeding or white moss.

5.X line barium meal inspection

X-ray manifestations of the stomach: 1 stomach angle widened, anti-parabolic; 2 stomach edge stiff, bilateral, stomach wall is not neat, there are filling defects, etc.; 3 gastric wrinkle swelling, intestinal tincture examination: tincture In the shape of the knot, the affected part may have a saw-like or stick-like shadow, and the upper intestinal tube expands.

Diagnosis and identification of anisakisis

diagnosis:

1. Epidemiological history and clinical manifestations: Where there are raw fish in the endemic area, there is abdominal pain, vomiting and peripheral blood eosinophils increased (about 10%), gastric juice and fecal occult blood positive should be suspected of this disease.

2. Gastroscopy: Found larvae and histopathological examination to find the cross-section of the worm can confirm the diagnosis, gastroscopy can see the mucus of the entire gastric mucosa increased, wrinkles and swelling, which can be seen in the white transparent head into the gastric mucosa of the live larva, spiral Or S-shaped disc, the mucosa around the body is erosive, with clots, bleeding or white moss.

3. X-ray barium meal examination: X-ray manifestations of the stomach: 1 stomach angle widened, anti-parabolic shape; 2 stomach edge stiffness, bilateral, stomach wall is not neat, there are filling defects, etc.; 8 gastric wrinkles, intestinal fistula Agent examination: The tincture is in the form of a knot, and the affected part can be seen as a saw-like or stick-like shadow, and the upper intestinal tube is expanded.

4. Immunological examination: The antigen was purified by the larvae of the apex larvae for the intradermal test. The serum specific IgE was elevated, and the latex agglutination test and the indirect fluorescent antibody test were positive.

5. Histopathological examination: Pathological examination of surgically removed specimens can be seen in the lesions of cellulitis, abscess, abscess granuloma and granulomatous lesions, and the cuts of the horns or muscle layers of the worms.

6. Molecular biology and technical examination: Recently, based on the simple eclipse, the ribosomal DNA fragments of C. elegans and C. elegans were different, and the restriction fragment length polymorphism based on polymerase chain reaction was established (PCR- The RFLP) and single-strand conformation polymorphism (SSCP) methods can be used to diagnose ischaemosis in humans and animals.

Identification:

The disease should be differentiated from digestive tract tumors, gastric cancer, gastric polyps, duodenal ulcers, cholelithiasis, cholecystitis, acute appendicitis, intestinal obstruction, acute gastroenteritis.

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.