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MMI 426 > Filariasis > Flashcards

Filariasis Flashcards

1
Q

Filariasis - lymphatic

A

Wuchereria bancrofti
Brugia malayi
Brugia timori

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2
Q

eye/skin - filariasis

A

Loa loa
Onchocerca volvulus
Mansonella streptocerca
Mansonella ozzardi
Mansonella perstans

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3
Q

W. bancrofti

A

nematode = round

adults reside in lymph vessels and nodes

long, slender, creamy white, thread-life worms with tapered ends

adult F = 80-100 nm x 0.2-0.2 mm = longer than M (40 mm x 0.1mm)

females are viviparous -> sheathed microfilaria

males have corkscrew tail, two spicules at posterior end

M & F live coiled together in the lymphatics

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4
Q

lifecycle of W. bancrofti

A
  • humans are only definitive host (reservoir for infection)
  • intermediate = Sculex mosquitos but also anopheles in rural Africa and Adian mosquito in Pacific islands

3rd stage larvae (infective) injected into person during mosquito blood feed -> lymphatic vessels -> node = mature to adults in few months

male and female worms mate and produce first stage larvae; male stage die after mating and F live up to 5-10 yrs

-> lymphatic vessels -> bloodstream (taken up by mosquitoes)

mosquito gut = microfilaria shed sheath 1-2 hrs of ingestion -> through stomach wall -> thoracic muscle (develop filariae form with 3rd stage larvae) -> infective forms go to mouth pods of mosquito (10-14 days development in mosquito)

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5
Q

female W. bancrofti microfilaria

A

50 000 microfilaria/year

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6
Q

pre-patent period of E. bancrofti

A

time of inoculation of 3rd stage larvae to detection of microfilaria in blood = 80 to 100 days

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7
Q

W. bancrofti microfilaria

A
  • diagnostic form (first stage microfilaria)
  • sheathed (no stain)
  • gently curved body
  • tail tapered to a point
  • nuclear column loosely packed
  • no nuclei in tail
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8
Q

T or F. 90% of skin/eye filariasis is W. bancrofti

A

F! lymphatic filariasis

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9
Q

vectors of W. bancrofti

A
  • mosquitoes (inefficient transmitters); need to stay in endemic areas for a while to be infected
  • microfilaria display no nocturnal periodi ity
    > in bloodstream from 10 pm to 2 am
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10
Q

hosts of W. bancrofti

A

only definitive is human
mosquitoes are intermediate host and vector

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11
Q

pathogeneis of W. bancrofti

A
  • adult worms do not cause inflammation but obstruction of lymph flow
  • symbiotic bacteria seen in the worms = cause some inflammation of lymphatic filariasis
  • Wolbachia required for homeostasis of adult filaria
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12
Q

clinical presentation of W. bancrofti

A

in endemic areas, can be asymptomatic or subclinical = abnormalities seen in tests (blood and proteins in urine)

  • increased eos, IgE, microscopic blood and protein in urine

early infections can result in pain, redness, and swelling of involved lymph vessels, and fever

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13
Q

chronic infection of W. bancrofti

A

lymphoedema
> genitals (M)
> breasts (F)
> limbs
- recurrent bacterial infections
- elephantiasis

not seen in travellers; years of exposure and repeated infections are required to see chronic changes
chronic = high depression rate and lose ~29 days of work

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14
Q

diagnosis of W. bancrofti

A

blood collection between 10 pm to 2 am = Giemsa or wright stain; microfliaria seen; gold std

filarial Ag test
> blood can be collected at any time
> more sensitive than blood smears

antifilarial Ab tests
> only useful in travellers from non-endemic areas; can distinguish between current or past infections and some cross-reactivity

molecular tests
> research only

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15
Q

T or F. Treatment for W. bancrofti exists but does not reverse elephantiasis

A

T

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16
Q

10% of lymphatic filiarisis

A

Brugya
- roundworm
- adults reside in lymph vessels and nodes

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17
Q

species of Brugya

A

B. malayi
B. timori

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18
Q

transmission of Brugya

A

host = humans, domestic and wild animals (ZOONOSIS)

vector = anopheles, Aedes, and Mansonia mosquitoes

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19
Q

Where is B. timori found?

A

sequestered to Timor islands of Indonesia

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20
Q

Lifecycle of Brugya

A

same as W. bancrofti except human stages also occur in animals

most Brugyan filaria also exhbit nocturnal periodicity = highes # microfiliaria in bloodstream between 10 PM to 2 AM

subperiodic variants = microfliaria variants in blood during daytime as well

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21
Q

clinical presentation of Brugya

A

same as W. bancrofti (acute, asymptomatic, chronic)
*chronic usually occurs below elbows and knees *

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22
Q

diagnosis for Brugya

A

blood collection between 10PM to 2 AM; no available antigen test

antibody tests and only useful for travellers from non-endemic areas

molecular tests for research only

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23
Q

identification of B. malayi

A

175-230mm

Sheathed (stains pink in Giemsa)

Tail tapered to a point

Nuclear column more tightly packed

Terminal and subterminal nuclei in the tail

24
Q

identification of B. timori

A

larger; ave 310 mm

sheathed but does not stain

longer cephalic space

more nuclei in tail and tail tapered

nuclear column more tightly packed

25
Treatment and prevention of Brugya
same as W. bancrofti but cannot be eliminated from endemic areas due to animal reservoirs if to decrease disease burdens = prevention of mosquito bites = bed nets and screens
26
African eye worm
Loa loa
27
T or F. Loa loa probability of infection increases with age
T
28
T or F. Travellers can be infected with Loa loa
T, but requires months to years of exposure
29
Hosts of Loa loa
only humans
30
Where is Loa loa found?
west and central frics
31
transmission of Loa loa
bite of deer or horse fly (Chrysops/ tabanid fly)
32
Loa loa life cycle
infective third stage of larvae inoculated into skinof host during blood meal of tabanid fly flies attracted to movmeent; bite in day time ] filarial larvae penertrate through subcutaneous stissue and mature in to adult worms ; 3 month process adult worms can migrate to any areas of body including conjutival tissue if eye 6-12 months post infection, female produces microfilaria into bloodstream -> taken up by tabanid fly mature into infective third stage larvae in 10-12 days adult worms can live for up; to 20 years but cant multiply in humans so adult worm burden increases w new infections each time new larvae are infected during blood meal of tabanid fly
33
clinical presentation of Loa loa
Most asymptomatic Transient localised swellings (**Calabar swellings**) > most likely allergic rxns Migration across subconjuntiva; usually resolve after worms leave eye ; trip across eye = 10-20 mins Symptoms recur as adults worms live up to 20 years Complications - Heart - Kidneys - Brain
34
diagnosis f Loa loa
when adult worm seen travelling in eye or microfilaria visualization in blood smear; Females larger travel at rate 1cm/min increased eos, IgE, blood, protein in urine diurnal periodicity; microfilariae at highest conctn in blood during 10Am to 2PM serology = antibodies to Loa loa but most useful for diagnosis of diseases in travellers antigen test being developed molecular assays available
35
Identification of Loa loa
250 - 300 um sheathed tapered tail nuclei extend to end of tail similar endemicity to W. bancrofti and Mansenella
36
treatment of Loa loa
used for symptomatic pts only rule out onchocerciasis first; no Wolbachia (endosymbiont bacteria)
37
2nd leading infectious cause of blindness
Onchocera volvulus
38
river bliondness
O. volvulus
39
hosts of O. volvulus
only humans transmission viablack fly (Simulium spp)
40
where does O. volvulus breed?
near fast flowing streams and rivers = river blindness
41
Four countries have been successful in eliminating the river blindness
Columbia, Mexico, Ecuador and Guatamala
42
O. volvulus life cycle
humans become infected 3rd stage fly larvae -> skin and mature there (12-18 months) female adult worms live in nodules while males live close by and travel between nodules to fertilize females adults live 10-15 yrs in humans and microfilaria have lifespan of 12-15 months if not ingested by black fly when black fly takes blood meal from infected ppl, they go to flight muscles of fly; in one week = 3rd stage larvae and go to bite parts of fly female black flies eat a blood meal to ovulate; diseases only transmitted by female black flies bite during the day
43
T or F. Endosymbiont Wolbachia is present in O. volvulus
T!
44
clinical presentation of O. volvuvus
Asymptomatic in some Most have itchy skin rashes, nodules under the skin vision changes (rxns to dead or dying filaria) -progress to blindness inflammation in skin can resullt in long-term damage = leopardskin appearance and thinning (cigarette paper appearance)
45
hanging groin
O. volvulus
46
The inflammation caused by O. volvulus larvae that die in the eye results initially in __________ lesions on the cornea that without treatment progress to permanent clouding of the cornea, resulting in _________
reverisble; blindness
47
diagnosis of O. volvulus
gold std = detection of microfilaria in skin snips; prepatent period = 12-18 months from initial infection to presence of microfilariae in skin adult worms in skin nodules are seen when surgically removed serology not useful
48
O. volvulus filaria description
unsheathed tail tapers to a point and often sharply bent no nuclei in tail
49
Mansonella species
M. perstans = solely human parasite M. ozzardi = primarily human but monkeys can be infected too M. streptocerca = primarily humans but wild chimps have been infected
50
Mansonella epidemiology
M. perstans West, East and Central Africa, Central and South America Transmitted by biting midges M. ozzardi Central and South America, Caribbean islands Transmitted by mainly by biting midges; black flies in some areas of S. America & Haiti M. streptocera Tropical rain forests of western and central Africa Transmitted by biting midges
51
M. perstans clinical presentation
transient subcutaneous swellings inflammation of the membranes covering the heart or lungs impaired vision if the microfilaria enter the eye fever, tiredness, ab pain, joint pains
52
Mansonella sp. lcinical presentation
largely symptomatic/mild if symptoms do occur, hard to know if due to Mansonella or bc of co-infection w other parasites
53
identification of M. perstans
adult worms in tissue or microfilaria in blood unsheathed round, blunted tail with nuclei extending to the end round terminal nucleus
54
M. streptocerca clinical presentations
itchy skin thickening of skin enlarged lymph nodes in axilla and inguinal areas
55
identification of M. streptocerca
sharply curved tail at posterior end need skin snips for ID
56
how to treat Mansonella spp.
treated with same drugs used for lymphatic filiarisis infection in travellers uncommon
57

MMI 426 (20 decks)

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