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164 Cards in this Set
- Front
- Back
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Name the 6 types of filaria that parasitize humans
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Wuchereria bancrofti
Brugia malayi and timori Onchocerca volvulus Loa loa Mansonella perstans, ozzardi and streptocerca Dirofilaria immitis |
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Where in world find filariae
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Tropics
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Where in body to filariae live?
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Tissue (not intestine)
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How are filariae spread?
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bloodsucking insects
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What are the offspring of adult female filaria?
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Microfilariae (highly modified eggs -- become wormlike in development
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What are the three most ommon prblematic filariae of humans?
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Wuchereria bancrofti
Brugia malayi Onchocerca volvulus |
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What filariae cause lympatic filariasis?
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Wucheria bancrofti and Brugia malayi
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What causes river blindness?
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Onchocerca volvulus
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What do filarial vectors suck in?
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Microfilariae
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What stage larvae of filariae develop in the insect host?
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Develop to L3, then await deposition into human with next insect feed
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What is periodicity?
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The presence of microfilariae only at certain times of day in the human blood
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Why do filariae show periodicity?
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Reflect the feeding cycles of their insect vectors
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What is a wolbachia symbiont?
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Rickettsia-like bacteria, called wolbachia, that live in certain filaria. Are necessary for parasite survival in some cases. May have a role in pathogenesis.
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What happens if you eliminate the wolbachia symbiont?
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You frequently kill the filiaria. Rx: doxy/tetracyclines
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Where in filariae do wolbachia symbiots live?
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Lateral canals
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How tell difference in microfilariae?
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Microscopy
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How to see microfilariae by microscopy?
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Thick smear stained with Giemsa or hematoxylin and eosin
May use concentration techniques |
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How do you concentrate a sample of filariae?
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Centrifuge blood lysed in 2% formalin (Knott's technique)
Filter thru a nucleopore membrane |
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What filariae are visible on skin snips?
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Onchocerca volvulus and Mansonella streptocerca
Incubate 4 hours in saline culture media Microfilariae migrate to liquid |
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Is there antigen detection for microfilariae?
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Yes
Helpful as numbers may be scant |
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Which microfilariae have a rapid format immunochromatographic test?
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Wuchereria bancrofti
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Is there antibody detection for filariea?
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Yes, limited value. Cross reacts between filaria and helminths
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Can you use PCR for detecting filaria?
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Yes, for Wucheria bancrofti and B. malayi
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What form of filaria is detectable by nodulectomy
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Onchocerciasis
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What form of filiaria is detected by removing worm from eye?
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Loa loa
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What is the cause of lymphatic filariasis?
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Most commonly wuchereria bancrofti
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Where in the world do you find wucheria bancrofti?
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India, SE Asia, W Pacific, W Afrcia, Brazil, S America, Costa Rica, Carribean
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What is the definitive host for wucheria bancrofti?
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Humans
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What parts of the body are impacted by wucheria infestation?
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Adults live in lymphatics in lymphatic vessels and sinuses. Inhibit lymph flow in lower legs, groin glands, epididymus, labia
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How do wucheria bancrofti microfilariae migrate?
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Via lymphatics to circulation OR migrate through lymphatic walls to circulation
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When do wucheria bancrofti circulate?
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Nocturnal periodicity (except diurnal subperioddic in western pacific)
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Which stage of wucheria bancrofti causes disease in humans?
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Adult stage blocking lymphatics
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Do wucheria bancrofti microfilaria have sheaths?
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Yes
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What is the vector for wucheria bancrofti?
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Mosquito (culex quinqefasciatus) -- night biting URBAN. Aedes, anopheles and mansonia also are vectors
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What is the vector for western Pacific version of wucheria bancrofti, which has a sub periodic cycle?
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Anopheles polynesienses, a day biter
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Describe wucheria bancrofti microfilaria
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Sheathed
245-300um Anterior bluntly rounded Posterior tapers to a point Adult females up to 10cm |
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How long can adult wucheria bancrofti filaria live?
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5+ years
Microfilaria 1-2 years Prepatent period almost a year |
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What is the definitive host for Brugia malayi
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Humans
Monkeys |
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Where in the world is Brugia malayi?
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SE asia
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What are the symptoms of Brugia malayi infection?
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Lymphedema
Elephantiasis HYDROCELE NOT SEEN |
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Are the microfilaria of Brugia malayi sheathed?
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Yes
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When are Brugia Malayi active?
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Nocturnal periodicity
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Whay is the Brugia malayi vector?
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Mansonia (primary)
Anopheles Aedes Armigeres Culex |
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What is the morphology of Brugia malayi microfilaria?
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Sheathed
200-275um Body nuclei extend almost to tail Gap between terminal and subterminal nuclei |
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Where do you find Brugia timori?
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Sunda Islands (Timor and Flores) in Indonesia
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What is the clinical presentation of Brugia timori?
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Same as Wucheria bancrofti and Brugia malayi (lymphedema, elephantiasis)
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What is the most common presentation of Wucheria/Brugia infestation?
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No sx, but easily demonstrable microfilaremia
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What is the EARLY stage of Wucheria/Brugia infestation?
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Afebrile lymphangitis/lymphadenitis
RETROGRADE lymphangitis (as adults get established in lymphatics) |
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What are the 3 stages of Wucheria/Brugia pathology?
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Living adults in lymphatics cause dilatation and chronic edema
Worms die and perilymphatic inflamation occurs, progressing to obstruction and collagen deposition (elephantiasis/hydrocele rarely) Recurrent trauma and bacterial infection cause chronic changes of elephantiasis |
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Do you see microfilaria in symptomatic disease from Wucheria and Brugia?
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No (remember, the disease is caused by adults in lymphatics)
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How long does it take to get a concerning filariaisis load?
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Normally 6+ months living in a place
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What is tropical pulmonary eosinophilia?
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Rare
Nocturnal asthma Severe eosinophila 30=80% Elevated IgE and filiarial antibodies Cough, fever, malaise Loss of appetite/weight Lymphadenopathy Hepatomegaly Responds to diethylcarbamazine |
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Where in the world do you see tropical pulmonary eosinophilia?
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India
Sri Lanka Malay Peninsula (presumptive filarial infestation) |
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What are the clinical sx of filarial wucheria/brugia infestation -- non-endemic:
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Urticaria
Pruritis |
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What are the clinical sx of filarial wucheria/brugia infestation -- endemic:
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Fever
Retrograde lymphangitis |
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What is the filarial dance sign?
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Finding nests of adult worms in the lymphatis of the scrotum and other sites
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What filiaria has a commercial serological detection kit for antigens?
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Wucheria bancrofti
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Treatment of wucheria/brugia?
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Diethylcarbamazine (DEC) 6mg/kg qd x 12d
Invermectin 400ucg/kg x1, repeat in 6-12 mos DEC + invermectin DEC + albendazole Albendazole + invermectin |
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Why is DEC (diethylcarbamazine) a great choice for filiariasis?
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Kills micro and macrofilaria
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How do invermectin and albendazole act on filaira?
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Kill only microfilarial stages
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Will killing adult filaria alter the course of lymphedema?
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No (except with TPE)
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How to manage lymphedema of microfilaria?
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Medicine doesn't change course (except with TPE)
Reduce edema Good hygiene Rarely surgery to reestablish lymphatic drainage |
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What is a population wide approach to reducing filariasis?
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DE (diethylcarbamazapine) in table sale 0.1-0.4 percent by weight salt)
Tried successfully in china |
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What causes river blindness?
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Onchocerca volvulus
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How many infected with onchocerciasis?
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18 million
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How many people visually imparied by oncho?
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800,000
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How many people bind from oncho?
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270,000
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How many at risk for oncho?
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>>100 million
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Where is oncho found?
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Central Africa
Yemen Saudi Central America Northern South America |
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What is the oncho vector?
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Blackfiles (near rivers) dependent on altitude (mid-altitude)_
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Sx of oncho?
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Severe itching
Disfiguring dermatitis Eye lesions |
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Economic concern of oncho?
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People flee good farmland due to risk of oncho
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What spreads L3 oncho?
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Simulium flies
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How long for L3 to mature to adult in oncho
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1 year
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Where does L1 stage of oncho mature?
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From human blood to blackfly...then develop in fly thoracic muscles
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How does blackfly (simulium fly) spread oncho?
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Spread through the wound of the blackfly bite
Enter sq tissues, encapsulate inside nodules, mature into adults in about a year) |
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Size of adult oncho?
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Female up to 50cm!
Males up to 5cm |
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Describe microfilaria of oncho
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Sheathless
Sharply pointed curved tails Found in free fluid in nodules, in dermal layers, blood, eye and urine |
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Which microfilaria is found in urine?
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Oncho
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What is the sq nodule of oncho called?
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Onchocercomata
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Where do you find onchocercomata?
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SQ
Over bony prominences IN africa: lower body In Central america: upper body |
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What causes "hanging groin"
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Oncho -- when skin tissue destroyed, losing elasticty and redundant folds occur
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What causes "leopard skin"
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Depigmentation of oncho
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What causes blindness of oncho?
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Microfilaria enter eye via conjunctiva
Conjunctivitis to slcerosing keratitis Follow ciliary vessels and nerves to cornea Follow nutrient vessels into optic nerve Inflammatory rxn causes secondary cataracts and ocular lesions |
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What are the common eye manifestations of oncho?
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Conjunctivits
Sclerosing keratitis Iritis Iridocyclitis Glaucoma Optic neuritis Choroiditis Retinitis Blindness |
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How long can adult oncho live in onchocercomata?
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Up to 15 years
Females can make microfilaria for 9 years |
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What is found in the onchocercomata?
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Several males and female (sometimes)
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How long can oncho larvae live
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2 years
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How to dx oncho?
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6 skin snips
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What filariasis can be dx'd by skin snips?
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Oncho
Mansonella sterptocerca |
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Can you see oncho by slitlamp?
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Yes, sometimes
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What is the Mazzotti test?
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Give DEC (diethylcarbamazine) 50mg...if provokes intense pruruitis within hours, positive
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What is the patch test to dx oncho?
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Patch of 10% DEC in lanolin with occlusive dressing...local dermatitis is + for oncho
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What is the treatment for oncho?
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Invermectin
Kills microfilaria Sterlizes adult female for several years 150ug/kg x 1 |
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Why not give DEC to oncho patients?
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Can precipitate severe Mazzotti rxn -- allergic sx, possible worse visual defect
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Can you remove onchocercomata surgically?
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Yes, but may be inaccessible
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What is the community mgmt of oncho?
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Mass Drug Administration with donated invermectin from Merck
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What causes African Eye Worm
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Loa loa
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Where in the world is loa loa?
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Rainforest of west and central africa
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Who gets loa loa?
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Any visitors to west/central africa endemic areas...even short periods of time
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What transmits loa loa?
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Bloodsooking/biting flies Chrysops
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When are loa loa found in the blood?
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Diurnal periodicity
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What is the pathology of loa loa infection?
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Episodic angioedema (calabar or fugitive swellings) -- painless hens egg size, sometimes > 1 year after
Travel in SQ tissue Urticaria Myalgias |
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What do adult loa loa look like
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Female 5-7cm Male 2-3cm
MF 250-300um MF sheathed, body nuclei to tip of tail |
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Dx loa loa?
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Sheathed microfilaria, diurnal periodicity
Eosinophilia Worm under conjunctiva Calabar swellings + PCR |
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How to prevent loa loa?
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Weekly DEC
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What filaria can cause encphalopathy?
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Loa loa -- when heavy infections of filaria are KILLED
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Where might you find loa loa MF?
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Spinal fluid
Urine Sputum Lungs Blood |
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What filaria are relative asymptomatic but can be found in blood and complicate dx of other?
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Mansonella species
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What is the ONLY filaria confined to the new world?
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Mansonella ozzardi (central/s america, caribbean)
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What is the periodicity of mansonella species?
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None
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What are the vectors for Mansonella ozzardi?
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Midges (culicoides)
Simulium in amazon basin |
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Where find adults of mansonella ozzardi?
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visceral adipose tissue
abdominal/thoracic cavities occasionally lymphatics |
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Where find MF of mansonella ozzardi?
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aperiodic
unsheathed/pointed tail Foudn in blood Sometimes dermal tissue |
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What is the pathogenesis of mansonella ozzardi
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considered non-pathogenic
frequently causes eosinophilia RARELY lymphadenopathy, urticaria, arthritis |
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How to treat mansonella ozzardi?
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DEC does NOT work
Invermectin |
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Where is mansonella perstans found in the world?
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Mostly Africa
South America |
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What is the reservoir for Mansonella perstans?
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Humans
Great apes |
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Sx of Mansonella perstans?
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Often asx
Agioedema (calabar like swellings) Pruritis Fevers Headach Neruo Manifestations Conjunctiva/eyelid swellings -- Ugandan eye worm |
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What causes "ugandan eye worm"?
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Mansonella perstans
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What is the reatment of mansonella perstans?
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Invermectin and albendazole (variable effects)
DEC not fully effecive, can cause Mazzoitt reaction |
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What filaria can cause Mazzotti reactions?
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Oncho
Mansonella perstans |
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Where is mansonella perstans found in the world
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Africa
South America |
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Where do adult mansonella perstans live in the body?
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Peritoneal cavity
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Where do MF mansonella perstans live?
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Blood
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What transmits ansonella perstans
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Culicoides midges
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What causes calabar like swellings?
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Loa loa
Mansonella perstans (Africa, S. America) |
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What is Ugandan eye worm
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Mansonella perstans
Nodules in eyelid and conjunctiva |
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Where is mansonella streptocerca found in the world?
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Congo basin, central africa
SW africa East Afrcia - uganda, kenya, s. sudan |
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What transmits mansonella streptocerca?
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Culicoides midge
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Where do the adults and MF of mansonella streptocerca live?
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SQ tissue
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What is the pathology of mansonella streptocerca?
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Often asx
Pruritis Adenopathy Found in skinsnips |
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Describe MF of mansonella streptocerca
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Found in tissue (on skin snip)
Aperiodic in blood Hook shaped tail Unsheathed |
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How to treat mansonella streptocerca
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DEC works but can have systemic sx (Mazotti rxn)
Invermetin kills MF Rx likely unnecessary if no sx |
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What filaria are consiered "diagnostic confounders"
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Mansonella spp
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What filaria cause lymphatic filariasis and have MF in blood?
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Wb
Bm Bt (confounder M ozzardi and M perstans) |
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What filariae cause adults in nodules, MF in skin?
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Oncho
(confounder M ozzardi (rarely in skin) in New World M sterptocerca in Afrcia |
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What filaria causes adults in sq, MF in blood?
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Loa loa
(confounder: Mansonell perstans in blood) |
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Which filaria is DEC the drug of choice
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W bancrofti (kills MF and adults)
Loa loa (kills adults and MF...drug of choice with caution) Oncho (kills MF...but Mazzoti rxn) |
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What is PLERM?
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Probable Loa Loa encephalopathy temporarily related to treatment with Mectizan) (invermenctin)
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What does DEC do in filarial infection?
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Wb Kills adult, MF. Drug of choice
OV: kills MF, get mazzotti rxn Loaloa: Kills MF, adults, drug of choice with caution |
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What does invermectin do in filarial infection?
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Wb; kills mf
Oncho: Kills MF, inhibits release of MF from adults Loa: Kills mf, Give with caution due to PLERM |
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What does albendazole do for Filarial infection?
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Wb: kills adults, scrotal nodules
Oncho: maybe reduces adult embryogeneisis Loa: Kills adults and scrotal nodules |
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What does doxy do for filarial infection?
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Kills forms that have wobachia
Wb: kills adults Ov: kills adults, reduces embryogenesis Loa: No effect -- has no wolbachia |
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Which significant filaria have wolbachia?
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Wucheria bancrofti
Oncho NOT Loa loa |
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What is Dirofilaria
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Filaria from dog heartworm
Occasional infects cats Rarely infects humans (accidental host - never patent) |
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What is the clinical presentation of dirofilaria?
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Solitary pulmonary nodule on xray mistaken for ca
Occasional sq nodules pulmonary infearction rarely described Rarely found in great vessels of humans |
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Species of Dirofilaria (dog heartworm) that cause sq nodules?
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D. tenuis
D. ursi D. repens D. immitis |
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Which dog hookworm causes cancer-appearing benign lesions in lung?
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Dirofilaria immitis
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Can dog heartworm (dirofilarria immitis) achieve pateny in humans?
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No
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Another name for guinea worm?
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Dracunculus medinensis
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What disease was the "firely serpent" of biblical times?
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Guinea worm
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Where find guinea worm?
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Middle east, pakistan, central india, africa,
Eliminated from western hemispherer Now restricted to sudan, nigeria |
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How get guinea worm?
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Ingest water infested with infected copepods
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What is the guinea worm vector?
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cyclops copepod
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Where does guinea worm live?
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Migrates from stomach to loose connective tissues
ature after a year, migrate to sq (usually LE) |
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How big is an adult female guinea worm?
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0.5-1.2m
Male 1-2cm |
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How does guinea worm infect water?
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Look of worm comes out of skin, uterus pops thru a ruptured part of the worm's skin, releases eggs
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Treatment of guinea worm?
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Metronidazole 200mg TID x 10d (paralyzes worm...easier to remove)
Mebendazole kills worm directly |
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How to prevent guinea worm?
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Filter water
Larvicidal treatment Create wells/prevent contamination |
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what may cause Mazzotti reaction?
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wolbachia rickettsia released from dyring worms, releasing TNF
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How many infected with lymphatic filariasis?
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120 million
(90% with bancrofti) |
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What causes PLERM?
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Treatment of Loa Loa with invermectin (encephalopathy in those with high levels microfilaremia)
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Do corticosteroids help reduce PLERM when treating Loa Loa?
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No
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