Human clonorchiasis is a biohelminthiasis from the group of trematodes, characterized by a predominant lesion of the biliary tract, pancreas and liver parenchyma.
Epidemiology
The main source of invasion is a person infected with clonorchs. In addition, dogs and cats invade reservoirs. The Chinese fluke is widely distributed in Japan, Vietnam, China, North Korea, the Amur basin, the Ob and Primorye. Helminth eggs excreted with faeces, when released into the aquatic environment, are swallowed by mollusks, in the body of which cercariae (larvae) form after about 14 days. When larvae enter the body of fish and crayfish from the intestine, they begin to actively move into the muscles and subcutaneous tissue. Thus, metacercariae are formed. A person becomes infected with clonorchiasis by eating raw, insufficiently thermally processed fish or crayfish. This is how clonorchiasis develops. Symptoms in patients usually begin to appear after the pathogen enters the small intestine.
Flukes: characteristics
Trematodes (flukes) are helminths belonging to the type of flatworms. As a rule, they have a leaf-shaped form. The size of themvaries in a wide range from 0.1 mm to 15 cm in length. The Chinese fluke can parasitize in the body of animals and humans. All types of flukes lead a parasitic lifestyle.
Morphology and biology of flukes
The fluke's body is compressed in the dorso-ventral direction. The cuticle together with the muscle layer form the musculoskeletal bursa, in which the internal organs are located. Trematodes are fixed with the help of special muscular organs - suckers. There can be two of them - oral and abdominal. The organs of fixation also include spikes on the cuticle and glandular pits.
Digestive system
In front of the body, the oral sucker is localized, at the bottom of which there is a mouth opening. The mouth is followed by the pharynx (pharynx) and an elongated esophagus. Intestinal tube - two blind-ending trunks. Flatworms usually do not have an anal opening. The remains of non-hydrolyzed food are thrown out through the mouth opening. Partial nutrition of flatworms can be carried out through the tegument.
Nervous and excretory system
The nervous system consists of nerve nodes located under the pharynx, and trunks extending to other parts of the body. The excretory system is represented by a complex system of tubules that form two excretory canals.
Reproductive system
The reproductive system of trematodes is very well developed. Flukes (with the exception of representatives of the genus Schistosomatata) are hermaphrodites (bisexual creatures).
The male reproductive apparatus, as a rule, consists of two testes. Semen ducts depart from them,which join into the common vas deferens. It is usually enclosed in a genital bursa (special muscular sac). The final part of the vas deferens is the cirrus (collective organ).
The composition of the female reproductive apparatus includes the ovary, oviduct, ootype, seminal receptacle, vitelline glands, Laurer canal, Melis' corpuscles and the uterus, which ends with the female genital opening.
Etiology
The causative agent of clonorchiasis is a trematode - a Chinese fluke. This helminth belongs to the family Opisthorchidae - Clonorchis sinensis. Helminthiasis was first described by McConnell in 1874. The Chinese fluke in the human body can parasitize up to 40 years. The body of the helminth is flat, lanceolate, 10–20 mm long and 2–4 mm wide. The eggs of flukes have a light golden color, on one of the poles the lid is clearly visible. Clonorchis sinensis in the adult stage can parasitize both humans and carnivorous mammals. The latter are the definitive hosts. Freshwater mollusks act as intermediates, freshwater crayfish and cyprinids act as additional ones.
Life cycle of trematodes
The life cycle of flukes consists of 4 periods:
- embryogonia;
- parthenogony;
- cystogonia;
- maritogonia.
Embryogony is the period of embryonic development of the germ cell in the trematode egg from fertilization to the release of miracidium. The duration of this phase is about a month. Parthenogony - the post-embryonic period of development of the larval stage in the bodyintermediate host. The presented phase begins from the formation of the sporocyst to the release of the cercariae into the environment. The duration of this period can vary from two weeks to five months.
Cystogony is the process of transformation of cercariae into adolescariae (in the environment) or metacercariae (in the body of an additional host). The duration of cystogonia is from several hours to two months.
Maritogony is the period of development of flukes in the body of the definitive host to the sexually mature stage (adult), which releases eggs into the environment. The duration of this stage is from one week to two months.
Pathogenesis
Patients living in endemic areas develop immunity, which is transmitted from mother to child through the placenta. Therefore, although such people are diagnosed with a disease, it has a milder course. The development of pathology is based on the mechanical effect of the fluke, the addition of secondary microflora, neurotrophic disorders and toxic-allergic reactions. In addition, clonorchs cause cirrhotic changes in the liver.
Disease symptoms
If you have been diagnosed with clonorchiasis, the symptoms of the pathology are similar to opisthorchiasis. In the acute phase of infection, there is a decrease in appetite, malaise, general weakness, manifestations of allergic reactions. With the progression of the disease, signs appear that characterize damage to the liver, pancreas and biliary tract. Sickcomplain of fever, as well as severe pain localized in the right hypochondrium.
Possible complications of the disease
It could be:
- chronic cholecystitis;
- cirrhosis of the liver;
- chronic gastroduodenitis;
- pancreatic and stomach cancer;
- chronic hepatitis.
Diagnosis of pathology
Diagnosis is made on the basis of epizootic and clinical data, as well as the results of helminthocoprological studies. To clarify the diagnosis, a biochemical blood test is performed (total protein, blood sugar, bilirubin, activity of alkaline phosphatase, aminotransferases, amylase, trypsin and lipase), instrumental (cholecystography, ultrasound examination of the gallbladder, liver, pancreas, fibrogastroduodenoscopy) and serological (RID, RNGA, PCR) research methods.
Therapy
If a patient is diagnosed with clonorchiasis, treatment should be comprehensive:
- diet therapy;
- anthelmintic drugs ("Biltricid", "Niklofolan", "Chloxil");
- antihistamines ("Calcium Gluconate", "Loratidin", "Suprastin");
- non-steroidal anti-inflammatory drugs (Ibuprofen, Nimisulide);
- enzymes ("Panzinorm", "Mezim", "Creon");
- sorbents ("Enterosgel", "Ataxil", "Polysorb");
- antispasmodics ("Papaverine", "No-shpa", "Mebeverine");
- macrolides ("Oleandomycin", "Spiramycin", "Azithromycin",Roxithromycin, Flurithromycin);
- choleretic drugs (Xylitol, Sorbitol, corn silk, immortelle, rose hips, mint leaves);
- hepatoprotectors ("Essentiale", "Ursochol").
