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81 Cards in this Set
- Front
- Back
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What are nematodes?
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Systemic round worms
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What type of worm is filaria?
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A round worm (nematode)
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Where do adult filaria live?
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Body cavity
Lymphatics Subcutaneous tissues |
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Where do the embryos (microfilaria) live?
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Blood or dermis
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Can adult filaria live in the blood/dermis?
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No, only the eggs can
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What does this parasite require?
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Insect or crustacean vector
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When can the parasite be seen in the blood?
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Only at night
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What are the main parasites in the blood?
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Wuchereria bancrofti: Tropics
Brugi malayi: SE Asia |
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What disease do the blood filaria cause?
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Lymphatic filariasis
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What are the skin filaria?
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Loa loa: African forest areas
Onchocerca volvulus: Africa, Central/South America |
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What diseses do the skin (cutaneous) filaria cause?
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Loa loa: eye worm
Onchocerca volvulus: River blindness |
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What diseases do wuchereria bancrofti and Brugia malayi cause?
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Lymphatic filiarisis
Elephantiasis |
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What kind of microfilaria do wuchereria and brugia have?
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Ensheathed
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What is the intermediate host for all filaria?
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Arthropod
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What is the most common cause of filaria?
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Bancrofti
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Which filaria species is responsible for most filariaris?
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90% Wuchereria (bancrofti)
10% Brugia |
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What is the life cycle of Wuchereria and Brugia?
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Pacific Asia: Mosquito usually feed at night, can find max amount of parasite
-Night (day) biting mosquitoes bite, takinng up microfilariae -1st-3rd stage larvae develop over 10-14 days in the thorax muscles of mosquito -Night (day) biting mosquitoes bite, introducing infective 3rd stage larvae -Larvae migrate to lymphatics where adults mature and mate (release microfilariae) -Microfilariae relesed into peripheral blood after 6-12 months |
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What are the clinical symptoms when the larvae migrate to the lymphatics?
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Lymphadenitis
Fever Lymphangitis, elephantiasis, hydrocele |
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What are the clinical symptoms when microfilariae are released into the peripheral blood?
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Tropical pulmonary eosinophilia
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What are the clinical states of Wuchereria?
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1) Asymptomatic
2) Inflammatory: lymphangitis, epididimitis/funicultis, filarial fevers, orchitis, filarial abscess 3) Obstructive: elephantiasis, chyluria, hydrocele 4) Tropical pulmonary eosinophilia |
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Describe the progression of the clinical pathology in lymphatic filariasis
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Incubation phase: from infection to appearance of microfilaria --> mostly symptomless
Acute/Inflammatory phase: Females reach maturity --> Release microfilaria: Intense lymphatic inflam, chills, fever, swollen LN, etc Obstructive phase: Blockage of lymphatic ducts --> Inflam of LN and walls: LN back up and passes into surrounding tissue, followed by fibrosis and elephantiasis |
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What are the pathological conditions ass't with lymphatic filariasis?
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Chylocele
Acute filarial lymphangitis Hydrocele Chyluria --> Also social and psychological impact |
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What does the serum look like in this disease?
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Whit (unlike schisto in which the serum is red)
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How do you diagnose this disease?
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Travel history to maximize best type of specimen and optimal collection time for filarial infection
1-direct examination (thick/thin smear) 2- Knotts concentration techniques 3- Millipore filtration 4- Ag capture |
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What is the thick smear used for?
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See if the parasite is there (use warm blood)
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What is the thin smear used for?
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Identify parasite species
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How is a diagnosis made?
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Presence of microfilaria: finger prick, skin snips
-Circulating filarial Ag (CFA--> Wuchereria): IgG4 ELISA tropical eosinophilia syndrome -Antifilarial Ab (IgG/IgE) -IgG4 to recombinant Ag |
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What is in the urine if infected with filaria?
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Urine contains lymph
--> Milky appearance ->Important for diagnosis |
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How can this be treated? **
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Diethylcarbamazine (DEC)
Ivermectin Albendazole |
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What does DEC do?
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Sensitizes microfilaria to phagocytosis
Only a proportion of adult worms are kililed -70-80% reduction in transmission using DEC |
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What does Ivermectin do?
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Activates Glu-Cl receptors and chloride channel permeability
90% reduction in transmission |
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What % reduction is there if use DEC + Ivermectin?
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up to 99%
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What does Albendazole do?
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For Wuchereria bancrofti
Acts by inhibiting the polymerization of b-tubulin and microtubule formation |
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What is loa loa known for?
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Eye worm
Loiasis calabar swellings |
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Where is Loa loa a problem?
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Rain forest of West Africa and equitorial Sudam
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What is the vector for Loa loa?
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Red fly
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Describe the life cycle of loa loa
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-Red fly *Day* bites and takes up microfilariae
-1sr-3rd stage larvae develop over to 10-12 days in fat body and migrate to proboscis -Red fly bites, injecting infective 3rd stage filariform larvae -Adults develop over 3 months and live 4-17 yrs -Microfilariae released (during the day) into peripheral blood after 6-12 mos (diagnostic stage) |
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What's different about this filaria?
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Loa loa can be transmitted during the day
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What is albendazole?
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Benzimidazole that acts by binding B-tubulin, preventing microtubule polymerization
Specific for parasitic tubulin |
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What is the best combination of drugs for this parasite?
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Albendazole and ivermetctin (works much better than albendazole and DEC)
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What are different ways to control this parasite?
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1) Chemotherapeutic control: reduced mortality, reduced tranmission. interrupt transmission (vector control)
2) Vector control: difficult to do 3) Avoidance from being bitten: mosquito nets, repellants, avoidance of habitats during peak biting times for the vector |
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What are the objectives of the global programme to eliminate to lymphatic filariasis?
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Interrupt transmission of infection (single-2 drug regimen)
To alleviate and prevent suffering and disability (2ry infections) |
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How did the WHO try to break transmission of this disease?
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Yearly mass treatments of entire communities with Albendazole in combo iwht DEC or Ivermectin
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What is required for effective immunity against Loa loa?
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Balance btw pro-inflam and anti-inflam
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What immune response is required?
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Promote Th2 type response
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What Ab are present in microfilarial and chronic pathology gps that have loa loa?
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IgG
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Are blocking levels of IgG higher in symptomatic or asymptomatic groups?
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Higher in asymptomatic MF patients gp
IgG4 is mosre specific to diagnose those with MF, while IgG1 is more specific to chronically infected ppl |
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What happens if IgG4 is depleted in MF sera?
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Reduction in blocking
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What happens when MF is released?
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Activates tolerogenic APC, releases IL-10, TGF-B
These go on to Tr1/Treg Activates B cell Releases IgG4 survival of adult parasites and microfilariae --> No pathology |
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What happens if there is no immunoregulation?
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Immunocompetent APC
-->Cytokines IL-12/4/IFN-y are releasaed Activates TH1/2/17 B cells activated Reelease IgE/IgG1 Activate effector cells Death of adult parasites and microfilariae |
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Is pathology caused in this case?
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Yes
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What happens if there is 4 yrs of drug ttreatment?
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Reduces prevalence of infections
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What does onchocerca volvulus cause?
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River blindness
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What kind of filariasis does onchocerca cause?
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Cutaneous
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Describe the life cycle of onchocerca volvulus
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Microfilariae taken up by blackfly bite
1st-3rd stage larvae develop in thorax muscles and proboscis of blackfly over 7-9 days Infective 3rd stage larvae enter skin with blackfly bile Larvae develop into adults in subcutaneous nodules where they can live for up to 15 years Microfilarieae released and migrate throughout the subcuatneous tissue and eye for 1-2 yrs |
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Is pathology caused in this case?
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Yes
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Is pathology caused in this case?
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Yes
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Is pathology caused in this case?
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Yes
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What happens if there is 4 yrs of drug ttreatment?
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Reduces prevalence of infections
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What happens if there is 4 yrs of drug ttreatment?
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Reduces prevalence of infections
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What happens if there is 4 yrs of drug ttreatment?
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Reduces prevalence of infections
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What does onchocerca volvulus cause?
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River blindness
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What does onchocerca volvulus cause?
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River blindness
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What does onchocerca volvulus cause?
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River blindness
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What kind of filariasis does onchocerca cause?
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Cutaneous
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What kind of filariasis does onchocerca cause?
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Cutaneous
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What kind of filariasis does onchocerca cause?
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Cutaneous
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Describe the life cycle of onchocerca volvulus
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Microfilariae taken up by blackfly bite
1st-3rd stage larvae develop in thorax muscles and proboscis of blackfly over 7-9 days Infective 3rd stage larvae enter skin with blackfly bile Larvae develop into adults in subcutaneous nodules where they can live for up to 15 years Microfilarieae released and migrate throughout the subcuatneous tissue and eye for 1-2 yrs |
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Describe the life cycle of onchocerca volvulus
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Microfilariae taken up by blackfly bite
1st-3rd stage larvae develop in thorax muscles and proboscis of blackfly over 7-9 days Infective 3rd stage larvae enter skin with blackfly bile Larvae develop into adults in subcutaneous nodules where they can live for up to 15 years Microfilarieae released and migrate throughout the subcuatneous tissue and eye for 1-2 yrs |
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Describe the life cycle of onchocerca volvulus
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Microfilariae taken up by blackfly bite
1st-3rd stage larvae develop in thorax muscles and proboscis of blackfly over 7-9 days Infective 3rd stage larvae enter skin with blackfly bile Larvae develop into adults in subcutaneous nodules where they can live for up to 15 years Microfilarieae released and migrate throughout the subcuatneous tissue and eye for 1-2 yrs |
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What does the microfilarie release cayse?
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Pruritus, dermatitis
Lymphadenopathy Punctate and sclerosing keratitis, blindness |
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How many microfilaria are released per day in onchocerca volvulus?
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up to 1900
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What are clinical signs of onchocerca filaria signs of disese?
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Skin lesions
Skin nodules Eye lesions -Can also cause elephantism |
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What is the pathology of onchocerca?
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Long-stnading, host inflam response to ptns from live/dead/dying microfilaria
Inflam response mediated by eosinophils |
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What happens when O. volvulus invades the cornea?
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Causes inflam of the sclera, cornea, iris and retina
Fibrosis leads to blindness 7-9 years later |
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What can dermatitis do to onchocerca?
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Lead to 2ry bacterial infection
Followed by thickening, discoloration and cracking of the skin: Lichenification |
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What's the dif btw onchocerca and loa loa?
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Onchocerca can actually go inside the eye and into the retina
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What is pannus formation?
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Slow progressive degenerative disease of the cornea
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Where is onchocerca the most problematic?
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Burkino Faso
Chad -->Where a lot of ppl end up blind due to onchocerciasis |
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How is this diagnosis of infection?
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Microfilaria: skin snip
Mazzoti test: DEC patch = itchings -Detection of filarial Ag -Detection of antifilarial Ab (O. volvulus IgG4) Complete blood cell count -- eosinophilia |
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How is this treated?
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1) Nodulectomy
2) Chemotherapy: DEC is more toxic Ivermectin: well-tolerated, action on microfilariae, reduces fecundity in adult female worms |
