Aveolar Hydatid Disease | |
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Other names | Alveolar echinococcosisAlveolar colloid of the liver,Alveolococcosis, Multilocular echinococcosis |
Specialty | Infectious diseases, helminthologist |
Causes | infection of larval stage Echinococcus multilocularis |
Alveolar hydatid disease (AHD) is a form of echinococcosis, or a disease that originates from a parasitic flatworm. AHD is caused by an infection of the flatworm species Echinococcus multilocularis . [1] Although alveolar echinococcosis is rarely diagnosed in humans and is not as widespread as cystic echinococcosis (caused by Echinococcus granulosus ), it is also still a serious disease that has a significantly high fatality rate. [2] It is considered one of the most life-threatening helminthic infections humans can have. [2]
It is most prevalent in China, Eastern France, Switzerland, Austria, Bulgaria, Turkey, Iran, Japan, Afghanistan, and Russia, and is mostly confined to the Northern hemisphere, south to around the 40th or 45th degree of Northern latitude, save some cases reported in Northern Africa. [2] [3] [4] [5] [6]
As the larvae grow in the liver, they create lesions. [2] If untreated, this progresses into abdominal mass and/or pain, jaundice, and finally liver failure. [7]
AHD is caused by the larval stage of E. mulitilocularis, a species of flatworm found in the Northern Hemisphere. [2] Humans make poor intermediate hosts for the worm, as they play no role in their life cycle. [5] However, when exposed the worms will still infect them. A major risk factor is when their domesticated dogs and cats eat wild, infected (typically arvicolid) rodents. [5] [8] [9] Their feces then will contain the worms' eggs, which have fully developed larval worms inside. [5] Humans become infected after eating food or water contaminated by embryonated eggs, or by handling an infected host like dogs and cats or by skinning infected foxes. [8] [10]
Once ingested by humans, "the oncospheres hatch in the stomach or small intestine, become activated, penetrate the epithelial layer, and migrate via blood and lymphatic vessels to the visceral organs, primarily the liver, where they develop to another larval stage, the metacestode." [5] The larval growth resembles a slow-moving liver tumor and it is able to destroy both the liver parenchyma and its function. [2]
Due to its infiltration into biliary and vascular liver tissue, it can be difficult to differentiate AHD and liver cancer. [2]
Early detection and treatment and radical surgery is key to preventing fatality from AHD. [2] Treatment may include liver resection to remove the larvae and chemotherapy using benzimidazoles. [7] [11] Chemotherapy must continue for many years, sometimes for the remainder of the patient's life. [12] Failure to comply with these expensive and difficult treatments will likely result in death for the patient. [7]
The disease is often progressive and destructive. [13] The growth happens slow, and so many people do not get symptoms until the later stages. [6] Central necrotic cavities are common in advanced stages of the disease. [14]
AHD is not as common as diseases caused by other flatworms, but it is still prevalent in the Northern hemisphere. It is not uncommon in China, with some communities having a 5% or more infection rate. [15] [16] In Europe, it is considered an emerging disease. [7] The increasing fox populations of Europe correlate with heightened reported cases. [17]
In 1855, Rudolf Virchow, the German pathologist, recognized that the disorder that was at the time known as colloid carcinoma of the liver, which was known for its tumor-like lesions in the liver, were actually caused by an Echinococcus species. For 100 year it was debated whether the species was E. granulosus or a different species. It was finally settled by two publications between 1954 and 1955, the former from Alaska and the latter from Germany. [5]
AHD is confined to the Northern hemisphere. [3] There are about 18,235 reported cases every year with 95% hailing from China. [18]
Wildlife research is working to detect the parasite in new areas. [19]
Echinococcosis is a parasitic disease caused by tapeworms of the Echinococcus type. The two main types of the disease are cystic echinococcosis and alveolar echinococcosis. Less common forms include polycystic echinococcosis and unicystic echinococcosis.
Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody stool, or blood in the urine. Those who have been infected for a long time may experience liver damage, kidney failure, infertility, or bladder cancer. In children, schistosomiasis may cause poor growth and learning difficulties.
Trematoda is a class of flatworms known as flukes or trematodes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five traditional vertebrate classes: mammals, birds, amphibians, reptiles, and fish.
Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may include shortness of breath and fever in the beginning of the disease. These may be followed by symptoms of abdominal swelling, abdominal pain, and diarrhea. Children are most commonly affected, and in this age group the infection may also cause poor weight gain, malnutrition, and learning problems.
Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is used to treat schistosomiasis, clonorchiasis, opisthorchiasis, tapeworm infections, cysticercosis, echinococcosis, paragonimiasis, fasciolopsiasis, and fasciolosis. It should not be used for worm infections of the eye. It is taken by mouth.
Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths. There are numerous species of these parasites, which are broadly classified into tapeworms, flukes, and roundworms. They often live in the gastrointestinal tract of their hosts, but they may also burrow into other organs, where they induce physiological damage.
Albendazole is a broad-spectrum antihelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, hookworm infection, trichuriasis, strongyloidiasis, taeniasis, clonorchiasis, opisthorchiasis, cutaneous larva migrans, giardiasis, and gnathostomiasis, among other diseases.
Echinococcus is a genus within Cestoda, a parasitic class of the platyhelminthes phylum. Human echinococcosis is an infectious disease caused by the following species: E. granulosus, E. multilocularis, E. vogeli or E. oligarthrus.
Echinococcus granulosus, also called the hydatid worm or dog tapeworm, is a cyclophyllid cestode that dwells in the small intestine of canids as an adult, but which has important intermediate hosts such as livestock and humans, where it causes cystic echinococcosis, also known as hydatid disease. The adult tapeworm ranges in length from 3 mm to 6 mm and has three proglottids ("segments") when intact—an immature proglottid, mature proglottid and a gravid proglottid. The average number of eggs per gravid proglottid is 823. Like all cyclophyllideans, E. granulosus has four suckers on its scolex ("head"), and E. granulosus also has a rostellum with hooks. Several strains of E. granulosus have been identified, and all but two are noted to be infective in humans.
Echinococcus multilocularis, the fox tapeworm, is a small cyclophyllid tapeworm found extensively in the northern hemisphere. E. multilocularis, along with other members of the Echinococcus genus, produce diseases known as echinococcosis. Unlike E. granulosus,E. multilocularis produces many small cysts that spread throughout the internal organs of the infected animal. The resultant disease is called alveolar echinococcosis, and is caused by ingesting the eggs of E. multilocularis.
Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections, hydatid disease, and giardia, among others. It is taken by mouth.
Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda. Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodaria. All tapeworms are endoparasites of vertebrates, living in the digestive tract or related ducts. Examples are the pork tapeworm with a human definitive host, and pigs as the secondary host, and Moniezia expansa, the definitive hosts of which are ruminants.
Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of many similar units known as proglottids—essentially packages of eggs which are regularly shed into the environment to infect other organisms. Species of the other subclass, Cestodaria, are mainly fish infecting parasites.
Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may also be called vermifuges or vermicides. Anthelmintics are used to treat people who are infected by helminths, a condition called helminthiasis. These drugs are also used to treat infected animals, particularly small ruminants such as goats and sheep.
Hymenolepis microstoma, also known as the rodent tapeworm, is an intestinal dwelling parasite. Adult worms live in the bile duct and small intestines of mice and rats, and larvae metamorphose in the haemocoel of beetles. It belongs to the genus Hymenolepis; tapeworms that cause hymenolepiasis. H. microstoma is prevalent in rodents worldwide, but rarely infects humans.
The PAIR procedure is a noninvasive treatment option to remove hydatid cysts. PAIR is considered an alternative treatment for cystic echinococcosis and is often indicated for patients who do not respond to surgery or benzimidazoles
Trematodiasis is a group of parasitic infections due different species of flukes, the trematodes. Symptoms can range from mild to severe depending on the species, number and location of trematodes in the infected organism. Symptoms depend on type of trematode present, and include chest and abdominal pain, high temperature, digestion issues, cough and shortness of breath, diarrhoea and change in appetite.
Carcinogenic parasites are parasitic organisms that depend on other organisms for their survival, and cause cancer in such hosts. Three species of flukes (trematodes) are medically-proven carcinogenic parasites, namely the urinary blood fluke, the Southeast Asian liver fluke and the Chinese liver fluke. S. haematobium is prevalent in Africa and the Middle East, and is the leading cause of bladder cancer. O. viverrini and C. sinensis are both found in eastern and southeastern Asia, and are responsible for cholangiocarcinoma. The International Agency for Research on Cancer declared them in 2009 as a Group 1 biological carcinogens in humans.
Echinococcus vogeli is a small cyclophyllid tapeworm found in Central and South America. E. vogeli, as well as other members of the genus Echinococcus, produce a disease called echinococcosis. Echinococcosis, also known has hydatidosis, is a result of ingesting the eggs of the genus Echinococcus. E. vogeli is similar to E. multilocularis in that both species produces many small cysts that spread throughout the internal organs of the infected animal. The ingestion of E. vogeli eggs, and the spreading of the cysts through infected host, will result in polycystic echinococcosis.
Cat worm infections, the infection of cats (Felidae) with parasitic worms, occur frequently. Most worm species occur worldwide in both domestic and other cats, but there are regional, species and lifestyle differences in the frequency of infestation. According to the classification of the corresponding parasites in the zoological system, infections can be divided into those caused by nematode and flatworms - in the case of the latter, mainly cestoda and trematoda - while other strains are of no veterinary significance. While threadworms usually do not require an intermediate host for their reproduction, the development cycle of flatworms always proceeds via alternate hosts.