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Human Parasitology > Nematodes Filarial > Flashcards

Nematodes Filarial Flashcards

1
Q

What are the species in the superfamily Filaroidea & which are of significant human health importance?

A
  1. Wuchereria bancrofti 2. Brugia malayi 3. Onchocerca Valvulus 4. Loa Loa 5. Dirofilaria immitis
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2
Q

Where do filarial worms live in the DH?

A

blood or tissues

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3
Q

How are filarial worms transmitted to the DH?

A

vector

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4
Q

What are microfilaria?

A

advanced embryos

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5
Q

What is the sheath?

A

flexible eggshell as covering membrane in blood dwelling species

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6
Q

Do all species have a sheath?

A

no tissue dwelling species are unsheathed

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7
Q

How long do mf survive in the host?

A

survive for many years

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8
Q

What is periodicity?

A

mf in peripheral blood only at certain times of day

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9
Q

Give an example of periodicity using Wuchereria bancrofti.

A

max number between 10pm & 2am bc vector is a night feeding mosquito vs. during the day mf are in blood vessels of deep tissue (lungs & liver) -> evolutionary advantage increases chance mf ingested by suitable vector

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10
Q

What disease is caused by Wuchereria bancrofti?

A

lymphatic filariasis (LF)

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11
Q

What is the size of the adult Wuchereria bancrofti worms and where do they live?

A

females: 8-10cm vs. male: 40cm

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12
Q

Are the mf of Wuchereria bancrofti sheathed?

A

yes

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13
Q

What is the vector for Wuchereria bancrofti?

A

mosquito

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14
Q

What are the 3 phases of Wuchereria bancrofti pathology?

A
  1. incubation phase 2. acute (inflammatory) phase 3. obstructive (chronic) phase
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15
Q

Describe the incubation phase of Wuchereria bancrofti infection.

A

asymptomatic, no detectable microfilarenia, ELISA - detect antigen in blood

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16
Q

What is microfilaremia?

A

early stage of parasite

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17
Q

Whatis episodic adenolymphangitis and in which phase of pathology does it occur?

A

attacks of fever, chills, & edema, iuguinal lymph nodes in the inflammatory (acute) phase

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18
Q

When does chronic pathology develop in microfilaremia infection?

A

obstructive phase 10-20 years after exposure

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19
Q

What is lymphoedema?

A

swelling of lymph tissue during obstructive phase of W. bancrofti

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20
Q

Compare the 3 grades of lymphoedema.

A
  1. grade I: transient & soft if apply pressure there is a pit in the skin rest and elevation needed 2. grade II: swelling is hard & permanent & does not pit with pressure 3. grade III: subcutaneous thickens, hyperkerastosis (hypertrophy of outer skin ayer), fissures, nodules, warty appearance
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21
Q

What is elephantiasis?

A
  1. phychological/social impact 2. swollen lymph nodes 3. ~10% of population 4. ages >40 rare is ages <25
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22
Q

What are the advantages of the CFA test for diagnosis of W. bancrofti infection?

A

test circulating filarial antigen

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23
Q

What can be observed using ultrasound for W. bancrofti infection?

A

adult worms in lymphatics

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24
Q

How if W. bancrofti infection treated?

A
  1. exercising limb to promote lymph flow 2. chemotherapy 3. treat bacterial & fungal infections
25
Q

What drugs are effective against W. bancrofti infection?

A
  1. DEC (diethylcarbamazine - may release components of parasite cuticle & stimulates immune response 2. albendazole - disrupts metabolic function 3. ivermectin (mectizan) - increases GABA at neutral junctions leads to faccid paralysis
26
Q

Why is hygiene important in preventing W. bancrofti infection?

A

H20, soap, & shoes prevent bacterial and fungal infections

27
Q

What are the costs of infection with lymphatic filariasis?

A
  1. costs of the disease 2. costs of treatment
28
Q

Compare the costs of disease and treatment for lymphatic filariasis.

A

disease: 1. permenant long term disability 2. social loss 3. decline in economic productivity vs. treatment: 2 cents/person/yr for DEC, 30 cents/person/yr for DEC fortified salt albendazole & ivermectin are donanted CFA test is $1/test: total cost $1.32/person/yr

29
Q

How do these costs and other factors contribute to the control of lymphatic filariasis?

A
  1. no amplification 2. no animal reservoir 3. simple & accurate diagnostic test 4. treatment is effective, inexpensive, large scale, combo of drugs, collateral health benefits 5. plans of action 6. drug company support
30
Q

What is the size of Brugia malayi adults?

A

female = 55mm vs. males = 25mm

31
Q

Is there periodicity in Brugia malayi?

A

yes: in peripheral blood at night

32
Q

Are Brugia malayi mf sheathed?

A

yes

33
Q

Brugia malayi is very similar to what other species?

A

W. bancrofti

34
Q

What are onchocercomas and where are they found?

A

cause river blindness found in Africa, Central/South America

35
Q

How long do onchocerca volvulus adults live?

A

10 years

36
Q

What is the vector in the life cycle of onchocerca volvulus?

A

blackfly (Simulian spp)

37
Q

What stage is infective to the vector in onchocerca volvulus?

A

L3

38
Q

How does the vector become infected in onchocerca volvulus?

A

blackfly has bloodmeal and scarifies skin -> pool of blood forms on skin -> fly laps up -> ingest mf

39
Q

What is the development of the parasite inside the vector in onchocerca volvulus?

A

mf -> mitohemocoel -> L1 -> L2 -> L3 -> migrates to mouthparts -> L4 -> adults in skin

40
Q

What is Wolbachia?

A

causes pathology in onchocerca volvulus. intracellular, inherited spp that controls reproductive functions and sex determination in many insect spp. gram negative - LPS causes host immune response and pathology

41
Q

What is LPS and how is it related to pathology in onchocerca volvulus infections?

A

produced by gram negative bacteria and produces host immune response and pathology

42
Q

Compare acute, chronic and ocular lesions in onchocerciasis.

A

acute: light, recent infections mf in skin -> presistant, itchy rash -> secondary infection skin begins to thicken & lymph nodes enlarge vs. chronic: heavy, long term infects, skin is thick & discolored “lizard” appearance loos of skin elasticity, femoral & ingunial lymph nodes enlarge & hang loose skin -> hanging groins vs. ocular lesions: mf invaded eye -> blindness

43
Q

Why do Simulium flies live near rivers?

A

lay eggs in water of fast flowing rivers

44
Q

How is onchocerciasis diagnosed?

A

skin snip - lift skin w/ forcep & use razor to slice thin layer of skin -> skin & saline -> microscope slide

45
Q

Why is it important not to draw blood during the skin snip?

A

won’t know which spp it is: tissue vs blood

46
Q

What is the treatment for onchocerciasis?

A
  1. ivermectin - kills mf 2. deoxycycline - kills adults 3. surgery - move onchocerca
47
Q

Briefly describe the Onchocerciasis Program of W. Africa & the Carter Center River Blindness Program.

A

Onchocerciasis Program of W. Africa: 1974 with 11 countries and ~20mil cases Dec 2002 program ended vs. Carter Center River Blindness Program: 1996 - Americas & Africa w/ MDP, mectizan distribution program

48
Q

In what part of the body do Loa loa adults live?

A

migrate freely in subcutaneous tissue

49
Q

What is the vector for Loa loa?

A

deerflies

50
Q

What is the pathology of Loa loa?

A

mild: adults winder through subcutaneous tissue and cause inflammatory rxn. caladbar swelling is localized, painful, temporary. migrate across conjuctive & cornea

51
Q

How is Loa loa infected diagnosed?

A

mf in blood

52
Q

How can Loa loa infection be treat?

A

surgery

53
Q

What is the common name of Dirofilaria immitis?

A

heartworm

54
Q

What is vector for Dirofilaria immitis?

A

mosquito

55
Q

What pathology results from Dirofilaria immitis?

A

fatigue & general loss of condition, cough

56
Q

How is Dirofilaria immitis infection diagnosed?

A

mf in blood

57
Q

How is Dirofilaria immitis infection treated?

A
  1. immiticide - contains arsenic that kills worms 2. surgery - caval syndrome (heavy infection & immiticide is contraindicated)
58
Q

What stage of Dirofilaria immitis is killed by immiticide?

A

adult worms. problem: dead worms can block blood vessel and arsenic can be toxic (low margin of safety)

59
Q

Why should a drug such as Heartgard be used?

A

ivermectin & pyrantel kill L3s injected by mosquitos

Human Parasitology (22 decks)

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