En primer lugar, son pastores, esquiladores de ovejas, veterinarios y todos aquellos que tienen contacto con estas personas. La incidencia de biohelmintos se asocia con el consumo abundante de verduras, frutas y verduras verdes. Esto se debe a las peculiaridades del clima y la intensidad del ganado. En la zona esteparia, predomina la variedad de ovejas, y en el bosque-estepa y bosque - el cerdo. En los humanos, las larvas del gusano causan una enfermedad compleja: la equinococosis. Estructura Echinococcus granulosus es el agente causal de la equinococosis, la etapa larvaria del encadenamiento del equinococo.
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The adult Echinococcus multilocularis 1. Gravid proglottids release eggs that are passed in the feces, and are immediately infectious. After ingestion by a suitable intermediate host, eggs hatch in the small intestine and releases a six-hooked oncosphere that penetrates the intestinal wall and migrates through the circulatory system into various organs primarily the liver for E.
Numerous protoscolices develop within these cysts. The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host. After ingestion, the protoscolices evaginate, attach to the intestinal mucosa , and develop into adult stages in 32 to 80 days. Humans are aberrant intermediate hosts, and become infected by ingesting eggs. Oncospheres are released in the intestine and cysts develop within in the liver.
Metastasis or dissemination to other organs e. Adults of E. Cysts are generally similar to those found in cystic echinocccosis but are multi-chambered. Hosts Echinococcus granulosus definitive hosts are wild and domestic canids. Natural intermediate hosts depend on genotype. For E. Other canids including domestic dogs, wolves, and raccoon dogs Nyctereutes procyonoides are also competent definitive hosts.
Many rodents can serve as intermediate hosts, but members of the subfamily Arvicolinae voles, lemmings, and related rodents are the most typical. The natural definitive host of E. Pacas Cuniculus paca and agoutis Dasyprocta spp. Geographic Distribution Echinococcus granulosus sensu lato occurs practically worldwide, and more frequently in rural, grazing areas where dogs ingest organs from infected animals. The geographic distribution of individual E. The lack of accurate case reporting and genotyping currently prevents any precise mapping of the true epidemiologic picture.
However, genotypes G1 and G3 associated with sheep are the most commonly reported at present and broadly distributed. In North America, Echinococcus granulosus is rarely reported in Canada and Alaska, and a few human cases have also been reported in Arizona and New Mexico in sheep-raising areas.
In the United States, most infections are diagnosed in immigrants from counties where cystic echinococcosis is endemic. In North America, Echinococcus multilocularis is found primarily in the north-central region as well as Alaska and Canada. Rare human cases have been reported in Alaska, the province of Manitoba, and Minnesota. Only a single autochthonous case in the United States Minnesota has been confirmed. Clinical Presentation Echinococcus granulosus infections often remain asymptomatic for years before the cysts grow large enough to cause symptoms in the affected organs.
The rate at which symptoms appear typically depends on the location of the cyst. Rupture of the cysts can produce a host reaction manifesting as fever, urticaria, eosinophilia, and potentially anaphylactic shock; rupture of the cyst may also lead to cyst dissemination.
Echinococcus multilocularis affects the liver as a slow growing, destructive tumor, often with abdominal pain and biliary obstruction being the only manifestations evident in early infection.
This may be misdiagnosed as liver cancer. Rarely, metastatic lesions into the lungs, spleen, and brain occur. Untreated infections have a high fatality rate. Echinococcus vogeli affects mainly the liver, where it acts as a slow growing tumor; secondary cystic development is common. Too few cases of E. Echinococcus granulosus in tissue. Upon ingestion of eggs by the human host, the oncospheres migrate from the intestinal lumen to other body sites via circulation and develop into hydatid cysts.
These cysts can be found in any part of the body, but are most common in the liver, lung and central nervous system. Figure A: Cross-section of an E. Host tissue A encapsulates the hydatid cyst wall, which is composed of an acellular laminated layer B and a nucleate germinal layer C from which the brood capsule D arises.
Inside the brood capsule are numerous protoscolices E with visible hooklets F. Figure B: Magnified view of an E. Note the row of hooklets. Figure C: Protoscolices liberated from a hydatid cyst. The two protoscolices on the right side of the image are evaginated. Figure D: Invaginated protoscolices liberated from a hydatid cyst. Echinococcus sp. The following images show the contents of a degenerating hydatid cyst from a liver aspirate, stained with Papanicolaou PAP stain.
Figure D: Higher magnification of the image in Figure C, showing a close-up of the hooklets. Notice the conspicuous calcareous corpuscles, characteristic of cestode infections. Echinococcus multilocularis in tissue. Echinococcus multilocularis is the second most common cause of echinococcosis in humans. The definitive hosts for E. Arvicoline rodents voles and related species also play an important role in the natural life cycle as intermediate hosts.
Figure B: Higher magnification x of the specimen in Figure A. Notice a pair of refractile hooks yellow arrows. Figure C: Alveolar E. Note the numerous protoscolices and convoluted, vesicular, multi-chambered appearance of the cyst. Figure D: Alveolar E. Note the numerous examples of protoscolices arrows and vesicular, multi-chambered appearance of the cyst.
Echinococcus spp. As dogs and other canids are the definitive hosts for most Echinococcus spp. Adults range from 1. The terminal proglottid is gravid and is longer than wide.
The scolex contains four suckers and a rostellum with 25 to 50 hooks. Figure A: Echinococcus granulosus adult, stained with carmine. This specimen has four segments 1: scolex; 2: immature proglottid; 3: mature proglottid; 4: gravid proglottid. Features highlighted are the armed rostellum R and suckers S of the scolex, and reproductive structures including the testes TE , cirrus sac CS , ovaries OV , branched uterus containing eggs UT , and genital pores on the mature and gravid proglottids GP.
Figure B: Close-up of the scolex of E. In this focal plane, one of the suckers is clearly visible, as is the ring of rostellar hooks. In seronegative patients with hepatic image findings compatible with echinococcosis, ultrasound guided fine needle biopsy may be useful for confirmation of diagnosis. During such procedures precautions must be taken to control allergic reactions or prevent secondary recurrence in the event of leakage of hydatid fluid or protoscolices.
Antibody Detection Immunodiagnostic tests can be very helpful in the diagnosis of echinococcal disease, particularly in conjunction with imaging, and should be used before invasive methods. However, the clinician must have some knowledge of the characteristics of the available tests and the patient and parasite factors in order to interpret assay results.
False-positive reactions may occur in persons with other cestode infections, some other helminth infections, cancer, and liver cirrhosis. Negative test results do not rule out echinococcosis because some cyst carriers do not have detectable antibodies. Whether the patient has detectable antibodies depends on the physical location, integrity, and vitality of the larval cyst.
Cystic echinococcal disease Echinococcus granulosus. At present, the best available serologic diagnosis is obtained by using combinations of tests.
As some tests may cross-react with sera from persons with cysticercosis, clinical and epidemiological information should also be used to support diagnosis. Alveolar echinococcal disease Echinococcus multilocularis. Most patients with alveolar disease have detectable antibodies. Immunoaffinity-purified E. Comparing serologic reactivity to Em2 antigen with that to antigens containing components of both E. Combining two purified E.
Em2 tests are more useful for postoperative follow-up than for monitoring the effectiveness of chemotherapy. Polycystic echinococcosis Echinococcus vogeli The serologic diagnosis of polycystic echinococcosis has not been extensively studied as infections with E. One antigen has been described Ev2 that distinguishes E. Laboratory Safety Standard protocols for the processing of histological sections and serum apply.
Infectious eggs are not encountered in a clinical diagnostic laboratory setting. Suggested Reading Kern, P. The echinococcoses: diagnosis, clinical management and burden of disease. In Advances in parasitology Vol. Academic Press. Siles-Lucas, M. Laboratory diagnosis of Echinococcus spp. In Advances in Parasitology Vol. Academic Press Vuitton, D.
Echinococcus granulosus – Hidatidosis
The adult Echinococcus multilocularis 1. Gravid proglottids release eggs that are passed in the feces, and are immediately infectious. After ingestion by a suitable intermediate host, eggs hatch in the small intestine and releases a six-hooked oncosphere that penetrates the intestinal wall and migrates through the circulatory system into various organs primarily the liver for E. Numerous protoscolices develop within these cysts.
Kagamuro The presentation of human CE is protean. Use of albendazole sulfoxide, albendazole sulfone, and combined solutions as scolicidal agents on hydatid cysts in vitro study. This paper reviews recent advances in classification and diagnosis and the currently available evidence for clinical decision-making in cystic echinococcosis of the liver. Echinococcosis CE2 may represent a relapsed CE3a, and CE3b a relapsed CE4, but long-term observations of large cohorts of patients are needed to confirm this hypothesis. Percutaneous treatments for abdominal CE were introduced in the mids, with the adoption of minimally invasive procedures made possible by new imaging tools, particularly CT and US[ 82 — 85 ].