Definicja
Giardiasis is a parasitic disease caused by infection with the protozoan Giardia intestinalis (syn. Giardia lamblia), belonging to flagellates.
Giardioza — Etiology
The protozoan is parasitic in the human small intestine, especially in the duodenum. It comes in two forms: vegetative – trophozoite and spore – cyst. The trophozoite is bilaterally symmetrical, pear-shaped and 10-20 µm in size. It has two oval nuclei and four pairs of flagella, multiplies by longitudinal division. Under the microscope, it shows great mobility in a fresh preparation. Under unfavorable conditions, the trophozoite turns into a cyst, which is resistant to environmental conditions. The cysts are oval, 8-18 µm in length, May. two or four testicles. The cytoplasm usually protrudes from the cell membrane and contains characteristic sickle-shaped structures. Infection occurs through the ingestion of the cyst, which is an invasive form of this parasite. After reaching the small intestine, cysts transform into trophozoites, which settle in it and multiply. From the intestine, trophozoites migrate to the duodenum and from there to the bile ducts and pancreatic ducts. They stick to the walls of these wires with a clinging disc (disc). There is a possibility of gastric involvement in the case of an acidity or regurgitation of gastric contents from the duodenum. From the duodenum, the protozoa enter the ileum. Periodically, the trophozoites transform into cysts and are excreted in the faeces. The number of cysts in 1 g of stool varies from several hundred to several million.
Giardioza – Epidemiology
Giardiasis is considered to be one of the most common causes of chronic and recurrent abdominal pain and diarrhea in preschool and school children. It is a worldwide disease, with a predominance of tropical and subtropical countries. In countries with poor sanitation, 20-30% of the population may be infected. In industrialized countries, the incidence is estimated at 2-5%, children are much more ill. In Poland, the last infected ranges from 0,8% to 1,35%, it is greater in the countryside than in the city. Infections occur in humans and in many species of wild and domestic animals. The strains found in humans are genetically different from those in animals, but transmission from animals to humans cannot be ruled out. Cysts are particularly contagious immediately after excretion, therefore, in poor hygiene conditions, a healthy person who is infected can be directly infected. Food transmission is possible if the cyst contamination has occurred after cooking the food. The reservoirs of contamination are water bodies, surface waters and mountain streams; contaminated drinking water supplies were often the cause of epidemics. In cool water, cysts can survive for months. Chlorination of water does not destroy them, boiling or filtering it is effective. Infestation can develop with the ingestion of 10 to 100 cysts.
Giardiasis — Etiopathogenic
The hatching period for giardiasis ranges from several days to several weeks. Symptoms of the disease occur only in some of the infected. The trophozoites attached to the surface of the enterocytes by the clinging disc destroy the brush limb, deforming the intestinal villi. This significantly reduces the absorbent surface of the villi and hinders the absorption of nutrients. There are symptoms of lactose intolerance and a malabsorption of fats. The local inflammatory reaction in the intestinal mucosa is slight. Changes in the histopathological picture occur only in a few people with a longer-lasting invasion. Infection is favored by other comorbidities, e.g. immune disorders (especially IgA deficiency), functional disorders of the stomach (gastric acid acidity) and conditions after gastric resection, catarrh of the small intestine or functional changes (celiac disease), inflammation of the bile ducts and infections (e.g. Candida albicans). During the invasion, a humoral and cellular defense response is triggered, but the role of these mechanisms in controlling the course of infection is not fully understood. The role of humoral immunity is particularly important, as evidenced by the severe course of invasion in patients with hypogammaglobulinemia. A history of giardiosis does not leave permanent immunity to an infection that may recur. Children and adolescents are more susceptible to infection than older people. People who have been infected with this parasite in the past are likely to develop partial resistance. The coexistence of giardiosis with chronic urticaria or reactive arthritis indicates a toxic-allergenic effect of the parasite, the mechanisms are not fully understood. Breastfeeding prevents giardiasis in newborns and infants.
Giardiasis – Clinical picture
The clinical picture is varied – from asymptomatic to cases with severe diarrhea and malabsorption. The course of invasion depends on the properties of the parasite itself and on the body’s defense reactions. Most infections are asymptomatic. The disease may begin suddenly or with gradually worsening symptoms (about 1-3 weeks after the infection). The severity of symptoms varies depending on the part of the gastrointestinal tract involved and the immune status of the patient. The most common complaints include abdominal pain (usually after eating) and diarrhea (varying in severity, fat or fermenting in nature). The stools are light, mushy, greasy, smelling and with a high air content. Symptoms of the upper gastrointestinal tract may predominate – nausea, vomiting, belching, flatulence. The acute form of the disease lasts about a week, relapses are common. Patients with chronic giardiasis do not always have a history of the acute phase of the disease. They have diarrhea rarely, loose stools appear more often, gas bloating with sulfur smell, weight loss. Such symptoms occur continuously or periodically, even for many years. Chronic disease causes malabsorption, dehydration, weight loss, growth retardation in children, and in extreme cases, death. If the gallbladder is involved, jaundice (intermittent, mild) may occur. In patients with hypogammaglobulinaemia, giardiasis can be life-threatening, its course is severe and difficult to treat. In people with AIDS, the course and results of treatment are similar to those in people without immunodeficiency. Cases of parenteral manifestation of giardiosis, such as chronic urticaria, uveitis, reactive arthritis, are described. However, it is not entirely clear whether these disorders were the result of infection or whether they were comorbidities.
Giardiasis – Diagnostics
The diagnosis of giardiasis is based on the parasitological examination of the feces for the presence of cysts, which are repeated three times at intervals of several days. Occasionally, trophozoites can be found in diarrhea. Stool evaluation should be performed by an experienced parasitologist as cysts can easily be confused with other parts of the stool. In the event of diagnostic difficulties, the duodenal content is examined with a gavage or the ENTERO test, in which trophozoites can be detected. Please note that the material must be delivered to the laboratory as soon as possible and tested within an hour. During transport, the sample must be protected against cooling (thermos), because after cooling down trophozoites lose their ability to move and it is difficult to distinguish them from other morphotic elements. Ready-made kits for stool immunoenzymatic (ELISA) testing for the presence of G. lamblia antigen are also used. A disadvantage of enzyme immunoassays is the frequent occurrence of false-positive results. Infection may be accompanied by slight eosinophilia in the peripheral blood.
A mail-order test for the presence of Giardia lamblia is available at medonetmarket.pl. A stool sample is collected at home and sent by courier to the laboratory.
Giardiasis – Treatment
Nitriomidazole preparations are used in the treatment of giardiasis. The first-line drug is metronidazole (Flagyl), which in adults is used in a dose of 750-1500 mg / day, in a divided dose three times a day, for 3-5 days, children are given 10-10 mg / kg / day. Recovery after a single treatment is approximately 15%. The drug is not used in pregnant and lactating women. In children, due to its affordable taste, furazolidone is used in a dose of 80-1 mg / kg bw, 2 times a day for 4-7 days, although its effectiveness is less. In the case of the ineffectiveness of the above-mentioned drugs, tinidazole (Fasigyl, Tinidazole) is used, in adults and children over 10 years of age in a single dose of 12 g or 2-400 mg / day in two doses for 600-3 days. Children under 5 years of age are administered 12-10 mg / kg bw / day in two doses for 15 days or in a single dose of 5-30 mg / kg bw / day. Cure is achieved in approximately 35% of cases. In case of ineffectiveness, mepacrine, albendazole, eucefuril are used. A stool examination should be performed 90 weeks after the end of treatment. In people with persistent infestation, another of the above-mentioned preparations is used. All cohabitants should always be tested and those with the infestation should be treated.
Giardiasis – Prognosis
Infection usually resolves spontaneously after several weeks or months, and rarely lasts for years. In patients with hypogammaglobulinaemia, the course of giardiasis may be life-threatening and treatment is difficult. Due to the ease of spreading the disease, the possibility of a severe course and the existing ailments, it is recommended to treat patients who have any clinical symptoms and all those infected from the environment.
Summation
Giardiasis is a parasitic disease caused by infection with the protozoan Giardia intestinalis (syn. Giardia lamblia), which parasitizes the human small intestine. It is the most common cause of chronic and recurrent abdominal pain in children. Infection occurs through the ingestion of the cyst. Infection can occur directly from an infected person and by consuming contaminated food and water that contains cysts. Most infections are asymptomatic. The most common complaints include abdominal pain, diarrhea, nausea, vomiting, belching and flatulence. The acute form of the disease lasts about a week, relapses are common. In chronic giardiosis, symptoms occur periodically over many years, resulting in malabsorption, weight loss, and growth retardation. Surviving giardiasis does not leave permanent immunity to infection. Nitriomidazole preparations are used in the treatment: metronidazole, tinidazole, furazolidone. All cohabitants should always be tested and those with the infestation should be treated.
Literature
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2. Magdzik W., Naruszewicz-Lesiuk D., Zieliński A .: Infectious and parasitic diseases,? Alfa-medica press, Bielsko-Biała 2004, pp. 85-88.
3. Nash TE, Weller PE: Infections with intestinal protozoa and goblin protozoa, [in:] Fauci A., Braunwald E., Isselbacher K. et al. (Eds.): Interna Harrison, 1998, vol. II, 1810-1815 (XIV edition).
4. Pawłowski Z., Stefanik J .: Giardioza, [in:] Pawłowski Z., Stefanik J. (ed.): Clinical parasitology in a multidisciplinary approach, PZWL, Warsaw 2004, pp. 279-281.
Source: J. Cianciara, J. Juszczyk, Infectious and parasitic diseases; Czelej Publishing House