Echinococcus granulosus and E. multilocularis are causative agents of hydatid cysts
Echinococcus granulosus
Epidemiology
The organism is common in Asia, Australia, Eastern Africa, southern Spain, southern parts of South America and northern parts of North America. The incidence of human infection about 1 to 2 per 1000 population and may be higher in rural areas of affected regions.
Morphology
This is the smallest of all tapeworms (3 to 9 mm long) with only 3 proglottids.
Life cycle
The adult worm lives in domestic and wild carnivorous animals. Eggs, passed by infected animals, are ingested by the grazing farm animals or man, localize in different organs and develop into hydatid cysts containing many larvae (proto-scolices or hydatid sand) (Figure 8). When other animals consume infected organs of these animals, proto-scolices escape the cyst, enter the small intestine and develop into adult worms (Figure 7). Echinococcus eggs, when swallowed by man, produce embryos that penetrate the small intestine, enter the circulation and form cysts in liver, lung, bones, and sometimes, brain. The cyst is round and measures 1 to 7 cm in diameter, although it may grow to be 30 cm. The cyst consists of an outer anuclear hyaline cuticula and an inner nucleated germinal layer containing clear yellow fluid. Daughter cysts attach to the germinal layer, although some cysts, known as brood cysts, may have only larvae (hydatid sand). Man is a dead end host.
Symptoms
The symptoms, comparable to those of a slowly growing tumor, depend upon the location of the cyst. Large abdominal cysts produce increasing discomfort. Liver cysts cause obstructive jaundice. Peribronchial cysts may produce pulmonary abscesses. Brain cysts produce intracranial pressure and Jacksonian epilepsy. Kidney cysts cause renal dysfunction. The contents of a cyst may produce anaphylactic responses.
Diagnosis
Clinical symptoms of a slow-growing tumor accompanied by eosinophilia are suggestive. Intradermal (Casoni) test with hydatid fluid is useful. Pulmonary cysts and calcified cysts can be visualized using x-rays. Antibodies against hydatid fluid antigens have been detected in a sizable population of infected individuals by ELISA or indirect hemagglutination test.
Treatment and control
Treatment involves surgical removal of cyst or inactivation of hydatid sand by injecting the cyst with 10% formalin and its removal within five minutes. It has been claimed that a high dose of Mebendazole results in some success. Preventive measures involve avoiding contact with infected dogs and cats and elimination of their infection
Sabtu, 09 Februari 2008
COCCIDIAL PARASITES
Coccidia in the genera Cryptosporidium, Eimeria, Isospora, arcocystis, and Toxoplasma are the most economically important group of protozoans in domestic animals in the United States. Historically the structure of the sporulated oocyst, especially the number of sporocysts and sporozoites, was used as a major characteristic to differentiate genera of coccidia.
Eimeria and isospora
· A. Host specificity - these parasities have a narrow host range -(stenoxenous).
· B. Organ specificity - these parasities are usually found in a specific organ.
· C. Site specificity within organ or cell - these parasities inhabit specific sites within an organ or cell.
· D. Monoxenous - coccidia usually parasitize one host, the definitive host.
· E. Reproduction
o 1. Schizogony (Merogony) -multiple fission.
o 2. Gamogony (syngamy) - union of similar gametes (Isogamy)
· F. Structure of sporulated oocyst
o 1. Eimeria - 4 sporocysts, each with 2 sporozoites
o 2. Isospora - 2 sporocysts, each with 4 sporozoites
Detailed Life Cycle of The Coccida Eimeria and Isospora
Infection of the definitive host begins with the ingestion of infective oocysts containing fully developed sporozoites (within sporocysts) which are freed in the lumen of the intestine by enzymic action of digestion upon the oocyst wall. The freed motile sporozoites penetrate epithelial cells of the intestine and round-up to form trophozoites which undergo a form of internal budding or cell division which is termed a schizont at this point (or schizogony the process). The later process (first generation schizonts) is terminated when the round internal cells elongate or become sickle shaped (which are termed merozoites, first generation) and are released (rupture host cells) into the intestinal lumen to enter other cells in their vicinity and repeating a second and/maybe a third generation of schiogony (merogony). Most merozoites of the second generation form macrogamethocytes with macrogametes which undergo no cell division. Those merozoites which develop into microgametocytes undergo further division forming biflagellated microgametes. The later leave host cells to penetrate other cells containing macrogametes resulting in fertilization, forming the zygote. The latter lays down a wall around itself from the eosinophilic plastic granules in its cytoplasm, thus forming the oocysts which breaks out of the host cells to be passed in the feces to sporulate or become infective in about 2-3 days under ideal conditions of temperature (Sporogony).
Eimeria and isospora
· A. Host specificity - these parasities have a narrow host range -(stenoxenous).
· B. Organ specificity - these parasities are usually found in a specific organ.
· C. Site specificity within organ or cell - these parasities inhabit specific sites within an organ or cell.
· D. Monoxenous - coccidia usually parasitize one host, the definitive host.
· E. Reproduction
o 1. Schizogony (Merogony) -multiple fission.
o 2. Gamogony (syngamy) - union of similar gametes (Isogamy)
· F. Structure of sporulated oocyst
o 1. Eimeria - 4 sporocysts, each with 2 sporozoites
o 2. Isospora - 2 sporocysts, each with 4 sporozoites
Detailed Life Cycle of The Coccida Eimeria and Isospora
Infection of the definitive host begins with the ingestion of infective oocysts containing fully developed sporozoites (within sporocysts) which are freed in the lumen of the intestine by enzymic action of digestion upon the oocyst wall. The freed motile sporozoites penetrate epithelial cells of the intestine and round-up to form trophozoites which undergo a form of internal budding or cell division which is termed a schizont at this point (or schizogony the process). The later process (first generation schizonts) is terminated when the round internal cells elongate or become sickle shaped (which are termed merozoites, first generation) and are released (rupture host cells) into the intestinal lumen to enter other cells in their vicinity and repeating a second and/maybe a third generation of schiogony (merogony). Most merozoites of the second generation form macrogamethocytes with macrogametes which undergo no cell division. Those merozoites which develop into microgametocytes undergo further division forming biflagellated microgametes. The later leave host cells to penetrate other cells containing macrogametes resulting in fertilization, forming the zygote. The latter lays down a wall around itself from the eosinophilic plastic granules in its cytoplasm, thus forming the oocysts which breaks out of the host cells to be passed in the feces to sporulate or become infective in about 2-3 days under ideal conditions of temperature (Sporogony).
Medically Important Protozoa
Protozoa means "first animal" and refers to simple eukaryotic organisms composed of a single cell (e.g. amoebae). Reproduction may be through simple cell division (e.g. the ameboflagellates) or sexual involving the fusion of gametes in part of the life cycle (e.g. the apicomplexa) as described below. Some protozoa can form a protective cyst stage capable of withstanding harsh environmental conditions.
Ameboflagellates
These use pseudopodia or flagella for locomotion.
Amoebae. These are characterized by a feeding and dividing trophozoite stage that can form a temporary resistant cyst stage.
Entamoeba histolytica is the cause of amoebic dysentery producing severe infection of the intestines that can spread to the liver. The organism is characterized by a trophozoite and cyst stage. E. histolytica is an example of a true parasite in that the organism cannot multiply outside of the host. Other amoebae occur naturally in soil and water environments which is their preferred habitat for feeding and replication. These amoebae are termed "free-living" as they have no natural host in which parasitism occurs. They can infect man opportunistically producing severe and often fatal disease. Such free-living amoebae are the Acanthameba, Naegleria fowleri and Balamuthia mandrillaris, all of which can infect the central nervous system. In addition, Acanthameba species can also invade the eye.
Flagellates
These organisms have flagella in the trophozoite stage. Trichomonas vaginalis is a common sexually transmitted organism causing trichomoniasis infection of the vagina and urethra. Giardia lamblia causes giardiasis producing symptoms of diarrhea and other intestinal disturbances. Infection arises from the ingestion of cysts, usually through contaminated water.
Trypanosoma brucei gambiense and T. brucei rhodesiense cause trypanosomiasis, more commonly known as African sleeping sickness. The disease is an arthropod (insect)-borne infections and is spread by the bite of the tsetse fly in which part of the trypanosome life cycle is completed. The eventual invasion of the central nervous system by the trypanosomes gives rise a comatosed state from which the common name for the disease is derived.
Trypanosoma cruzi causes Chagas' disease (American trypanosomiasis). The intermediate host in this case are triatomid bugs that feed off the blood of man. Infection results from the inoculation of the bug's feces that contains the organism into the bite wound. Individuals who survive the acute stage of the disease are frequently left with chronic and progressive neuronal and smooth muscle lesions in the heart and gastrointestinal tract. T. cruzi has an extensive reservoir in wild and domestic mammals and therefore Chagas' disease is a zoonosis.
Ameboflagellates
These use pseudopodia or flagella for locomotion.
Amoebae. These are characterized by a feeding and dividing trophozoite stage that can form a temporary resistant cyst stage.
Entamoeba histolytica is the cause of amoebic dysentery producing severe infection of the intestines that can spread to the liver. The organism is characterized by a trophozoite and cyst stage. E. histolytica is an example of a true parasite in that the organism cannot multiply outside of the host. Other amoebae occur naturally in soil and water environments which is their preferred habitat for feeding and replication. These amoebae are termed "free-living" as they have no natural host in which parasitism occurs. They can infect man opportunistically producing severe and often fatal disease. Such free-living amoebae are the Acanthameba, Naegleria fowleri and Balamuthia mandrillaris, all of which can infect the central nervous system. In addition, Acanthameba species can also invade the eye.
Flagellates
These organisms have flagella in the trophozoite stage. Trichomonas vaginalis is a common sexually transmitted organism causing trichomoniasis infection of the vagina and urethra. Giardia lamblia causes giardiasis producing symptoms of diarrhea and other intestinal disturbances. Infection arises from the ingestion of cysts, usually through contaminated water.
Trypanosoma brucei gambiense and T. brucei rhodesiense cause trypanosomiasis, more commonly known as African sleeping sickness. The disease is an arthropod (insect)-borne infections and is spread by the bite of the tsetse fly in which part of the trypanosome life cycle is completed. The eventual invasion of the central nervous system by the trypanosomes gives rise a comatosed state from which the common name for the disease is derived.
Trypanosoma cruzi causes Chagas' disease (American trypanosomiasis). The intermediate host in this case are triatomid bugs that feed off the blood of man. Infection results from the inoculation of the bug's feces that contains the organism into the bite wound. Individuals who survive the acute stage of the disease are frequently left with chronic and progressive neuronal and smooth muscle lesions in the heart and gastrointestinal tract. T. cruzi has an extensive reservoir in wild and domestic mammals and therefore Chagas' disease is a zoonosis.
Snail-Mediated Helminthiases
This important group of snail-transmitted helminthiases is all caused by trematodes (flukes) that undergo a complicated cycle involving various species of land or aquatic snails. The most significant of these fluke infections is schistosomiasis and over 200 million people are estimated to be infected world-wide. The three common species infecting man, Schistosoma mansoni, S. japonicum and S. haematobium have similar life cycles. Eggs are passed in the urine (S. haematobium) or feces (Schistosoma mansoni and S. japonicum) and hatch in natural waters. Miracidia hatch from the eggs, penetrate suitable snails and develop two generations of sporocysts. The last of these then produces fork-tailed cercariae. These cercariae penetrate the skin when a new host comes into contact with the contaminated water. Once through the skin the cercariae shed their tails and become schistosomulae that then migrate through the tissues to the liver. Here male and female flukes copulate and migrate to either the bladder or rectum where eggs are laid. Schistosomiasis can result in chronic liver, spleen and bladder damage.
Fascioliasis. Fasciola hepatica is found in most herbivores (but primarily sheep) that graze in wet pasturage where the intermediate host, snails of the genus Lymnaea, are found. F. hepatica eggs, shed from the infected primary host, mature into the embryonated form in the environment. These then hatch and release a motile miracidia that seeks out and penetrates the tissue of the intermediate snail host. Cercaria are produced in the snail that when released into the environment can encyst to produce metacercariae. In temperate climates man is often infected by eating wild watercress on which metacercariae have collected. After being ingested, the metacercariae pass through the duodenal wall and penetrate the liver capsule. Following maturation of the young flukes, the adults finally come to lie in the bile ducts or adjacent liver tissue. Here they cause severe damage to the biliary tract and eggs are passed with the bile into the feces to continue the cycle.
Fascioliasis. Fasciola hepatica is found in most herbivores (but primarily sheep) that graze in wet pasturage where the intermediate host, snails of the genus Lymnaea, are found. F. hepatica eggs, shed from the infected primary host, mature into the embryonated form in the environment. These then hatch and release a motile miracidia that seeks out and penetrates the tissue of the intermediate snail host. Cercaria are produced in the snail that when released into the environment can encyst to produce metacercariae. In temperate climates man is often infected by eating wild watercress on which metacercariae have collected. After being ingested, the metacercariae pass through the duodenal wall and penetrate the liver capsule. Following maturation of the young flukes, the adults finally come to lie in the bile ducts or adjacent liver tissue. Here they cause severe damage to the biliary tract and eggs are passed with the bile into the feces to continue the cycle.
Soil-Mediated Helminthiases
Soil-transmitted helminthic infections are of two types: the hookworms, which undergo a cycle of development in the soil (the larvae being infective), and a group of nematodes that survive in the soil merely as eggs that have to be ingested in order for the cycle to continue.
Hookworms. The most common hookworms are Ancylostoma duodenale and Necator americanus. Adults attach to the walls of the jejunum and females lay large numbers of eggs that are passed out with the feces. The eggs hatch in the soil and infect man by usually burrowing through the soles of the feet. The larvae then migrate to infect the heart and lungs before passing into the tracheae, pharynx and then the small intestine.
Strongyloides stercoralis. Females live in the mucosal glands of the small intestine. Eggs hatch in these glands and the larvae are passed with the feces into the soil. As with other hookworms, infection results from the larvae burrowing into the skin. The rest of the life cycle is as for A. duodenale and N. americanus.
Ascariasis. Adult worms of Ascaris lumbricoides live in the small intestine where they lay large numbers of eggs that are passed out with the feces. Unlike the hookworms, the eggs are the infectious form in which the larvae develop. When ingested, the eggs hatch in the jejunum, penetrate the mucosa and are carried through the hepatic circulation to the heart and lungs. They again enter the stomach via the tracheae and oesophagus before growing to adulthood in the small intestine. Pneumonitis and intestinal obstruction may accompany heavy infestations.
Toxocariasis. The disease results from the accidental infection of man with eggs of the ascarid roundworm of the dog, Toxocara canis, and cat, T. cati. The life cycle is the same as that of Ascaris but the invasive larvae become arrested in various tissues where they are phagocytosed. In the process they induce marked eosinophilia and local tissue reaction commonly involving the liver and eye.
Trichurias. Trichuris trichiura ("whipworm") inhabits the caecum where they attach to the mucosa. Eggs from the mature worms are passed with the feces and develop in the soil. When swallowed, the eggs hatch in the small intestine and the developing larvae pass directly to their attachment sites in the large intestine. Heavy infections can cause abdominal pain and chronic bloody diarrhea that may result in rectal prolapse.
Hookworms. The most common hookworms are Ancylostoma duodenale and Necator americanus. Adults attach to the walls of the jejunum and females lay large numbers of eggs that are passed out with the feces. The eggs hatch in the soil and infect man by usually burrowing through the soles of the feet. The larvae then migrate to infect the heart and lungs before passing into the tracheae, pharynx and then the small intestine.
Strongyloides stercoralis. Females live in the mucosal glands of the small intestine. Eggs hatch in these glands and the larvae are passed with the feces into the soil. As with other hookworms, infection results from the larvae burrowing into the skin. The rest of the life cycle is as for A. duodenale and N. americanus.
Ascariasis. Adult worms of Ascaris lumbricoides live in the small intestine where they lay large numbers of eggs that are passed out with the feces. Unlike the hookworms, the eggs are the infectious form in which the larvae develop. When ingested, the eggs hatch in the jejunum, penetrate the mucosa and are carried through the hepatic circulation to the heart and lungs. They again enter the stomach via the tracheae and oesophagus before growing to adulthood in the small intestine. Pneumonitis and intestinal obstruction may accompany heavy infestations.
Toxocariasis. The disease results from the accidental infection of man with eggs of the ascarid roundworm of the dog, Toxocara canis, and cat, T. cati. The life cycle is the same as that of Ascaris but the invasive larvae become arrested in various tissues where they are phagocytosed. In the process they induce marked eosinophilia and local tissue reaction commonly involving the liver and eye.
Trichurias. Trichuris trichiura ("whipworm") inhabits the caecum where they attach to the mucosa. Eggs from the mature worms are passed with the feces and develop in the soil. When swallowed, the eggs hatch in the small intestine and the developing larvae pass directly to their attachment sites in the large intestine. Heavy infections can cause abdominal pain and chronic bloody diarrhea that may result in rectal prolapse.
Genus ostertagia pada ruminat
Cacing ini merupakan cacing lambung coklat atau cacing lambung berukuran sedang pada ruminansia. Kepala dan kapsula bukal kecil. Terdapat papila-papila servikal. Spikulum pendek, sama panjang, dan berakhir pada 2 atau 3 tonjolan. Terdapat sebuah gubernakulum. Vulva terletak pada 1/5 bagian posterior tubuh, dan kadang-kadang tertutup oleh cuping kutikuler. Siklus hidupnya mirip dengan siklus Trichostrongylus.
Ostertagia ostertagi terdapat pada abomasum sapi, domba dan ruminansia lain. Cacing ini berwarna coklat kemerahan. Panjang yang jantan 6-8 mm dengan spikulum 220-230 mikron berakhir pada tiga tonjolan tumpul berkait; gubernakulum dengan panjang 65 mikron. Bnetinanya 8-10 mm dengan telur berukuran 74-90 x 38-44 mikron.
Ostertagia lyrata merupakan cacing abomasum lain pada sapi yang juga ditemukan pada domba dan berbagai ruminansia liar. Yang jantan mencapai sekitar 9 mm dengan spikulum sekitar 230 mikron dan gubernakulum sekitar 63 mikron. Cacing betina mencapai panjang 9 mm dengan telur 75-85 x 34-42 mikron.
Ostertagia circumcincta terdapat pada abomasum domba dan ruminansia lain (tidak pada sapi) di seluruh dunia, dan merupakan ostertagia yang paling penting pada domba. Yang jantan 7-9 mm, dengan spikulum 280-320 mikron dan gubernakulum 90 mikron. Cacing betina 10-12 mm, dengan telur 85-103 x 44-58 mikron.
Ostertagia ostertagi terdapat pada abomasum sapi, domba dan ruminansia lain. Cacing ini berwarna coklat kemerahan. Panjang yang jantan 6-8 mm dengan spikulum 220-230 mikron berakhir pada tiga tonjolan tumpul berkait; gubernakulum dengan panjang 65 mikron. Bnetinanya 8-10 mm dengan telur berukuran 74-90 x 38-44 mikron.
Ostertagia lyrata merupakan cacing abomasum lain pada sapi yang juga ditemukan pada domba dan berbagai ruminansia liar. Yang jantan mencapai sekitar 9 mm dengan spikulum sekitar 230 mikron dan gubernakulum sekitar 63 mikron. Cacing betina mencapai panjang 9 mm dengan telur 75-85 x 34-42 mikron.
Ostertagia circumcincta terdapat pada abomasum domba dan ruminansia lain (tidak pada sapi) di seluruh dunia, dan merupakan ostertagia yang paling penting pada domba. Yang jantan 7-9 mm, dengan spikulum 280-320 mikron dan gubernakulum 90 mikron. Cacing betina 10-12 mm, dengan telur 85-103 x 44-58 mikron.
Heterakis gallinarum
Ciri-ciri : Cacing jantan panjangnya 4-13 mm, dan diameter 120-470 mikron dengan alat penghisap preanal berdiameter 38-114 mikron, spikulum kanan panjangnya 0,85-2,80 mm dan spikulum kiri 0,37-1,10 mm. Cacing betina 8-15 mm, dengan telur berbentuk elips, berdinding tebal berukuran 63-75 x 36-48 mikron.
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