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46 Cards in this Set
- Front
- Back
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The helminths can live in the humans for years, decades.
General symptoms? |
metabolic product of the helminth
- protein allergisation eozinophilia, urticaria, asthma - food requirement of the helminths food withdrawal from the host losing weight, anaemia - mechanical effect damage to the skin - specific organ symptoms during the migration of the larva intestinal obstruction lymphatic vessels, blood vessels obstruction - carcinogenesis (schistosoma) |
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Diagnosis of helmiths
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- serology
- macroscopic examination - microscopic examination - concentration methods: - larva: larva migration test - positive thermo-hydrotaxis of the larvas - egg: - flotation: specific weight of the media > egg specific weight (supernatant) - sedimentation: specific weight of the media < egg specific weight (in the sediment) - biopsy: - cysticercus in the muscle |
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Prevention
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- washing hands
- washing vegetables, fruits - avoid eating not sufficiently roasted, cooked meat … etc. |
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Therapy
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- drugs usually inhibit one of the catalytic enzyme system of the helmiths
- they usually have wide spectrum - eg: Mebendazole, Praziquntel, Thiabendazole |
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Nemathelminthes
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- round worms
- separate - sexed complete digestive system |
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Nematodes
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- thread worm
- resistant, non cellular cuticle - spindle or whip shape |
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Platyhelminthes
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– flatworms
- hermaphroditic or separated sexed uncomplete or lack of digestive system |
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Trematodes
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- fluke
- leaf-shaped - cellular epithelium - pair of suckers |
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Cestodes
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- tape worm
strobila (segments) inside: complete male and female reproduction system - no mouth absorption |
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Entrobius vermicularis
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- spin worm
"ab ano ad os" World-wide distribution with the highest prevalence in temperate and cold climates and in crowded conditions larva leaves the egg in the duodenum migration into the colon fertilization gravid female goes down to the anus and the embryonated ovum is deposited on perianal skin (a few thousand/day) itching scratching autoinfection eggs are rarely found in faeces, they are more easily found in the perianal region Scotch-tape smear can be used to pick up the eggs and must be made in the morning before defecation and bathing |
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Life cycle of
Enterobius vermicularis |
da
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Trichuris trichiura
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- whip form
world-wide distribution, it is the third most common worm of man geohelminth egg is laid into the ground, in wet, worm soil the maturation of the egg takes place release of the larva infection with soil contaminated food (larva) Treatment: mebendazol |
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Ascaris lumbricoides
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has a world-wide distribution and is most prevalent in tropical areas
25% of the world population harbours the parasite geohelminth infect. with soil contam. egg larva leaves the egg in the duodenum through the small intestine wall blood stream lung alveolus bronchus trachea pharynx oesophagus small intestine sexually mature worm gravid female release the egg with faeces in soil immature or adult A. lumbricoides are sometimes passed in stools adult males are 15-20 cm, femals are 20-35 cm Diagnosis: - detection of eggs in faeces Treatment: - mebendazol, levamizol |
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Ancylostoma duodenale, Necator americanus
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hook worm
A. duodenale is prevalent in Southern Europe, North Africa, Northern Asia; N. americanus is the predominant species in the Western and equatorial Africa Many areas are endemic for both species larva inf. through skin blood stream lung, pharynx, small intestine (sexually mature worm) sucking blood (0.3-0.9 ml/day) A. duodenale cause a daily blood loss of 0,15 ml compared to 0,03 ml for N.americanus. adults live in the small intestine attached to intestinal mucosa where they feed on villous tissue sucking blood Hypocromic, microcytic anemia is the main clinical manifestation of the disease epigastric pain and eosinophilia are often observed Hypoproteinemia, malnutrition occur in heavily infected people Treatment: - mebendazole or albendazole |
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Ancylostoma duodenale, Necator americanus life cycle
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das
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Strongyloides stercoralis
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geohelminth
Endemic in tropics, subtropics and warm moist climates Widespread in Eastern Europe and in the Mediterranean region About 1% of the world population infected The infection is acquired by skin contact with contaminated soil filariform larva through the skin blood-lung small intestine sexually mature worm egg: rhabditiform larva leaving with faeces soil maturation filariform larva filariform larva lung (autoinfection) Eggs are excreted with faeces in the external environment, transform into either filariform larvae (L3, the infective stage) (the direct development cycle) or into free-living adult males and females in the soil (the indirect development cycle) |
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Strongyloides stercoralis
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In the indirect development cycle several reproductive cycle of the free-living forms can occur - they produce eggs (40-70 µm) which can develop into rhabditiform larvae and into infectious third stage larvae
Filariform larvae (L3) penetrate the skin by releasing hydrolitic enzymes enter dermal vessels and migrate through the blood or lymphatic channels to the hearth and lungs In the lungs the larvae break out of the capillaries into alveolar spaces, migrate up the respiratory tract into the pharynx they are then swallowed, reaching the small intestine During this process, larvae moult to the fourth stage (L4) and only females develop into adults |
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Strongyloides stercoralis
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infections may persist for over 30 years
In the intestinal lumen rhabditiform larvae may directly transform in filariform larvae here they may penetrate the colonic mucosa or the perianal skin causing autoinfection. Autoinfection explains the long duration of the infection and the possible multiplication within the host (hyperinfection) Disease: Symptoms depend on: the host immune system and the moulting regulatory mechanisms of the parasite chronic infection and hyperinfection (with or without dissemination) Light infections may be asymptomatic usually with eosinophilia |
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Strongyloides stercoralis
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patients may complain about mild gastrointestinal symptoms (light intermittent abdominal pain and diarrhea), or pruritus of anal skin or larva currens
heavy infections are characterized by more severe intestinal symptoms (nausea, vomiting, diarrhea), frequently with malabsorption, gastrointestinal bledding, jejunal perforation, paralytic ileus, granulomatous hepatitis, eosinophilic ascites often with marked eosinophilia. Diagnosis: infection is diagnosed by the presence in faeces of first-stage rhabditoid larvae Antibody detection is usefull in patients with hypereosinophilia and negative stool examination Immunodiagnosis by indirect immunofluorescence Treatment: - thiabendazole and ivermectine |
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life cycle of the Toxocara (cati, canis)
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Toxocara (cati, canis)
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– geohelminth
- Human toxocariasis is caused by nematodes of the genus Toxocara - final host: cat, dog gravid female vacate the eggs in the gut with faeces into the soil maturation in the soil larva in human granulomatosus infection (liver, brain) especially T.canis (common roundworm of dogs). - the infection is acquired from ingestion of embryonated eggs released in the soil - after ingestion, L2 larvae begin a somatic migration to the lungs, liver, eye, CNS. Disease: the clinical presentation depends on the number of larvae ingested and the degree of allergic response two major syndromes have been identified: Visceral Larva Migrans (VLM) characterized by fever, malaise, leucocytosis with hypereosinophilia, hepatomegaly, cough, myalgias, high titers of isohaemagglutinins, other manifestation: myocarditis, encephalitis and pneumonia - Ocular Larva Migrans (OLM) characterised by retinal granulomas and uveitis blindness Diagnosis: - western-blot analysis - detection of |
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Trichinella spiralis
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Trichinella spiralis
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spiralis - pork meat
eating cyst beating meat (encysted larva) release of the larva maturation copulation gravid female under the mucous membrane of the the small intestine larva born lymphatics, blood vessels encystation in muscle infective for years the cyst is formed outside by a fibrous capsule and inside by an eosinophil infiltration around the tightly coiled larvae Disease: trichinellosis massive infection may cause acute enteritis myalgia, fever, periorbital oedema the migration and the later muscle encystation of larvae may be asymptomatic or cause serious generalized disease with possible miocardial and brain pathology Diagnosis: is based on serology and on finding of larvae in the striated muscle biopsy Treatment: - tiabendazol |
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Wuchereria bancrofti and Brugia malayi
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Vector:
Wuchereria bancrofti: mosquitoes of the genus Culex, Anopheles and Aedes Brugia malayi: mosquitoes of the genus Mansonia, Anopheles and Aedes bite filariform larva lymph. node for 1 year (inflamm. in the lymph. node elephanthiasis) microfilaria circulation in the blood during the night back to the mosquito lymphatic filariases have a wide geographic distribution W. bancrofti and B. malayi infect ~128 milion people - and about 43 milion have symptoms B. malayi infection is endemic in Asia (China, Corea, India, Indonesia, Malaysia, Philippines, Sri Lanka) W. bancrofti has a larger distribution : China, India, Indonesia, Japan, Malaysia, Philippines, South-East Asia, Sri Lanka, Tropical Africa, Central and South America, Pacific Islands Microfilariae are usually nocturnally periodic but sub-periodic strains of B. malayi and W. bancrofti are observed |
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human round worms life cycle
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Lymphatic filariasis
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adults live in the lymphatic vessels and lymphnodes where they cause dilatation
inflammatory infiltrates and blockage of the lymphatic circulation adenolymphangitis, orchitis, epididimitis associated with fever are the commonest manifestation of the acute stage of the infection eosinophilia is frequent at this stage lymphoedema particularly of the legs and scrotum hydrocoeles and chyluria are the result of the progression of the disease genital manifestations are frequent in W.bancrofti infections while they are rare during B.malayi infections Treatment: - diethylcarbamazine - ivermectine, albendazole used alone or in combination |
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Loa-Loa
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the infection is endemic in West and Central Africa, especially in Angola, Cameroun, Congo, Eq. Guinea, Gabon, Nigeria, RCA, Zaire
vector: Chrysops fly after injection larvae develop into adults in 6 months and may live for 17 years in the organism bite migration in the subcutis gravid female microfilaria blood circul. during the day the most typical: conjunctiva Microfilariae are present in blood without periodicity, count is mandatory before therapy Diagnosis: microfilariae can be demonstrated in blood with fluorochromes: Acridine orange stain direct diagnosis by observation of microfilariae in blood indirect diagnostic tests: IF cross-reaction with other nematode infections limits the usefulness of serology in these patients immunodiagnosis by indirect immunofluorescence, antigen: frozen sections of Dirofilaria immitis Treatment: - diethilcarbamazin |
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Oncocerca volvulus
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onchocerciasis occurs especially in Tropical Africa - high endemicity in B. Faso and Ghana
vector: Simulium genus - black fly migration in the subcutis eye blindness - O. volvulus: the larvae enter the host tissues - and develop to adults in subcutaneous nodules in about 1 year Adults live for 8-10 years in nodules females contain eggs and larvae in different stages of development after being released by the adult female microfilariae escape to the subcutaneous tissues and the eye and can be recovered with blood-free skin snips Disease: "river blindness" due to the presence of microfilariae in the ocular structures other clinical manifestations: pruritic dermatitis with lichenification and thickening of skin Diagnosis: by fresh examination of blood-free skin snips biopsies must be kept in saline for 1 to 3 hours to allow migration of microfilariae. |
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Dracunculus medinensis
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drinking water (copepods with the larva) larva migration subcutis - cutis with the help of toxin vesicle formation in the water bursts worm in the water uterus bursts larva in the water copepodes eat them
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life cycle of human tape worms
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Taenia saginata , Taenia solium
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Taenia saginata - cattle
Taenia solium – pig Taeniasis: world-wide distribution. T. saginata is prevalent in regions where cattle are raised: Africa, Middle-East, Central and South America, Europa and Asia T. solium is prevalent in Central and South America (expecially in Mexico), Africa, South-Est Asia, Eastern Europe, Micronesia Taeniasis occurs when raw or undercooked unfrozen beef (T.saginata) or pork (T.solium) are eaten. - in the muscle "cystisercus" human infected by eating the meat small intestine larva maturation mature worm egg filled segments break off pass out with faeces pork or cattle embryo blood stream muscle cysticercus |
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T. saginata
T. solium scolex |
T. saginata may measure 9 m, whereas T. solium may reach 6 m
T. saginata scolex is square, 1-2 mm in diameter with 4 suckers T. solium scolex has a rostellum with hooklets symptoms include abdominal discomfort or pain, abdominal distension, nausea, diarrhoea, malaise, anxiety, anorexia |
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Echinococcus granulosus
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dog), E. multilocularis (fox) - final host
distribution with a higher prevalence in South-America (Argentina, Uruguay), Europe (mediterranean bassin), Northern Africa, Middle East, South-Central and East Asia intermed. host: cattle, pig - accid. intermed. host: human Disease: hydatidosis is caused by the larval stage of E. granulosus after ingestion of eggs the onchospheres penetrate the intestinal mucosa and reach host organs (mainly liver and lung) where they encyst within a week reaching 1 cm in diameter in about 5 months the cysts (2 to 30 cm) are constituted by an external acellular cuticule and an inner cellular "germinal" layer (10-25 µ) that produces the brood capsules containing 6-12 protoscolices or single protoscolices the larvae (scolices) develop from the germinal layer the mature protoscolices have 4 suckers and a rostellum with hooklets and can be observed in the hydatid fluid |
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Echinococcus granulosus
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Echinococcus granulosus
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spontaneous or surgical rupture of the cyst can originate a secondary hydatidosis - - the liver is the most common site of development of cysts (50-75%)
pulmonary infection is observed in about 20-30% of patients any other organ can be affected: nervous system, heart, bones, spleen eyes, muscles are the most common sites Diagnosis: the presence of isolated hooklets is diagnostic for hydatidosis lesions can be detected by CT scan or echography ELISA, Western Blot Treatment: is based on surgical and/or medical therapy (albendazole) |
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Echinococcus multilocularis
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multilocularis (E. multilocularis) The “small fox tapeworm”
- prevalent in North America (Alaska and northern Canada), in Europe (France, Switzerland, Austria and Germany), in Asia (from the White Sea to the Behring strait in the north and from Turkey, through Afghanistan, Iran, India, China, Mongolia to north Japan in the south) causes alveolar echinococcosis (AE) in intermediate hosts parasites red and arctic foxes (dogs and cats are the definitive hosts) definitive hosts are always carnivores in the definitive hosts the adult tapeworm, consisting of 2 to 6 proglottids, lives attached to the luminal surface of the small intestine it is assumed that the intermediate host acquires the infections through the ingestion of contaminated fruits and vegetables |
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Echinococcus multilocularis
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When the intermediate hosts (predominantly rodents or other small mammals, or, accidentally, humans) ingest eggs, the onchosphere hatches from the egg in the duodenum
the activated oncosphere penetrates the small intestine, enters blood vessels and reaches primarily the liver via the portal vein in the liver the oncosphere proliferates into the metacestode surrounded by an inner germinative membrane and an outer laminated layer the lifecycle is completed when an intermediate host carrier of viable protoscolices within the cysts, is devoured by a definite host |
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Echinococcus multilocularis
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Disease: - the liver is the organ primarily affected
metastases are mainly observed in cases of advanced disease and may affect almost any organ the disease either spreads via direct contact or via blood vessels secondary AE mostly affects the brain, the lungs, soft tissue, the spine and other bony structures the disease is primarily characterized by an expansive and infiltrative growth in the liver clinical features may be absent for many years and mostly become apparent in advanced disease they may include hepatomegaly, jaundice, abdominal pain, weight loss, fever and manifestations of secondarily affected organs. Diagnosis: computed tomography (CT) and magnetic-resonance-imaging (MRI) are used for serology ELISA Treatment: The only curative treatment for AE to date is total surgical resection combined with chemotherapy benzimidazoles |
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Hymenolepis nana
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Cosmopolitan, is endemic in both temperate and tropical regions but most prevalent in conditions of poor sanitation
- swallowed eggs - maturing in intestine – developing the helmith |
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human flukes life cycle
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Paragonimus westermani
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infection occurs in Asia (especially in China, Corea, India, Japan, Laos, Philippines, Sri Lanka, Taiwan, Thailand, Vietnam), Central-West Africa, South America (Ecuador, Peru, Venezuela)
- eating infected raw crab – excystation in small intestine – migration to lung - maturation of helmith in lung coughing the eggs – swallowing – faeces containing eggs Disease: pneumonia caoughing, bloody sputum Treatment: praziquantel |
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Fasciola hepatica
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F. hepatica infection is found in rural areas of temperate and tropical regions, related to cattle herding
High prevalence is described in Europe and Latin America The adults live in biliary ducts for up to 10 years larva excystation in the duodenum larva through the gut wall hepar liver maturate worm egg in the bile duct pass out with faeces fresh water (miracidium) snail plants human after excistation in the small intestine, metacercariae penetrate the intestinal wall , cross the liver parenchima to the bile ducts eggs can be found in faeces 3-4 months after penetration. Diagnosis: the diagnosis is confirmed by the presence of eggs in faeces serology is useful when the clinical picture is compatible and eggs are not found |
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Schistosoma - Bilharsiasis
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Schistosoma - Bilharsiasis
S. mansoni - intermediate host are snails (Biomphalaria) S. japonicum - intermediate host are snails (Onchomelania) S. haematobium - intermediate host of S. haematobium are snails (Bulinus) cercarae are the infective forms fresh water cercaria larva penetration through the skin blood stream liver: maturation ven. plexus eggs through the lumen wall pass out snail cercaria S. mansoni:. geographical distribution: is endemic in 43 countries in Africa and Brazil, Suriname, Venezuela and in the Caribbean adult schistosomes live in pairs in the portal system and in the mesenteric venules each female lays about 300 eggs per day viable eggs contain the motile larva, the miracidium after breaking the shell the ciliated miracidium moves in the water and reaches the mollusca |
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Schistosoma Disease:
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hepatosplenic schistosomiasis occurs in S. mansoni and S. japonicum infections
it results by eggs embolization in hepatic venules formation of granulomas and portal fibrosis hepatosplenomegaly and hepatic insufficiency Diagnosis: - serological tests |
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S. japonicum:
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geographic distribution: Southeast Asia and western Pacific countries (including China, the Philipines and Indonesia)
adult schistosomes live in pairs in the portal system and in mesenteric venules each female may lay up to 2.000-3.000 eggs per day S. haematobium: after encountering the skin, the cercariae penetrate and lose the tail transforming into schistosomulae is reported from 54 countries in Africa adult schistosomes live in pairs in the pelvic veins (especially in the venous plexus surrounding the bladder) each female lays about 150 eggs per day |
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S. japonicum:
Disease: |
eggs are the main agent of pathology inducing granuloma formation
bladder wall enlargement, haematuria hyperplasia of the mucosa due to the presence of granuloma fibrosis and calcification follow with polips formation in bladder and urether stenosis hydronephrosis and possibly cancer are late complications of the infection damage of the seminal vescicles seems to correlate with the degree of the obstructive uropathy Diagnosis: identification of eggs in urinary sediment viable eggs contain a motile miracidium eggs can occasionally be found in faeces ELISA, IF, RIA Treatment:- praziquantel |
