NTD's Flashcards

1
Q

Review Lifecycle of W. Bancrofti

A
  1. mosquito takes blood meal, L3 larvae enter skin
  2. migrate via lymphatics, usually settling in groin and develop into adults
  3. adults produced sheathed microfilaria
  4. mosquito ingests microfilaria in blood meal
  5. mf sheds sheat to midgut and migrate to thoracic muscles
  6. L1 larva
  7. L3 Larva
  8. migrate to head and proboscis and enter and so on
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2
Q

How does Filiariasis present clinically?

A
  1. acute filarial fever without lymphadenitis
  2. acute adenolymphangitis (ADL)
    • sometimes abscess at site of affected node with secondary bac infection
    • several recurrences per year
    • acute inflammatory attacks with secondary bacterial infection, damage to small lymphatics and fibrosis and progression to elephantiasis
  3. acute dermatolymphangiolymphadenitis
    • secondary infection severe, edemal
  4. Acute Filarial Lymphangitis with death of adult worm, either spont or after treatment
    • usually mild, rarely causes residual lymphoma
  5. Chronic lymphatic filiariasis
    • may develop months to years later, with or without acut sx
    • recurrent infections, often strep, may lead to GN
  6. Other presentations
    1. hydrocele
    2. lymph scrotum
    3. acute epididimitis
    4. funiculitis - inflammation of spermatic cord
    5. cyluria, chylous diarrhea, chylous ascites, due to rupture of dilated lymphatics
    6. monoarthritis, glomerulonephritis
  7. Don’t forget social consequences
    • stigma, employment, maritability
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3
Q

Diff dx filiariasis

  1. filarial fever
  2. variable groin glands
  3. filarial glandular enlargement
  4. filarial orchitis, funiculitis, hydrocele
  5. chyluria
  6. elephantiasis
A
  1. filiarial fever: malaria, other acute or recurrent fevers, acute bacterial lymphangitis
  2. groin mass: hernias, hanging groin of onchocerciasis
  3. fil gland enlargement: chronic infection, tb, lymphogranuloma inguinale, reticuloses (var mycosis fungoides), lymphoma, leukemia
  4. fil orchitis, funiculitis, hydrocele - acute infection, tb, s. hematobium, “surgical”
  5. chyluria: other causes lymphatic obstn eg tb
  6. elephantiasis: chronic siderosilicosis - particles of sand from barefoot blocks them, milroy’s disease - congenital, lepromatous leprosy, repeated strep infections feet
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4
Q

Dx Filiariasis

blood findings

how to confirm dx

A
  • eosinophilia common during acute stages
  • parasitological dx: Giemsa thick films at heightened periodicity
    • concentration techniques
  • DEC prov test - discarded - onchocerciasis contraindication
  • RDT CFA tests for Ag now available widespread use, ELISA and ICT test
    • sens and specific, periodicity not a problem
  • PCR
  • scrotal US - filiarial dance sign
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5
Q

Filiariasis Treatment

options

community treatment

adverse reactions to what?

general and local

A
  • DEC
    • mf count falls within monthe, remains low for 2-3 months
    • repeat after 1 month
    • limited killing of adult worm
    • should be avoided in areas endemic for onchocerca or Loa Loa because Mazotti rxn or encephalopathy
  • Ivermectin
    • kills mf but not adults, usually used in combi with DEC or albendazole
  • Albendazole kills mf (+ adults if prolonged course)
  • Community based tx
    • Yearly DEC with Ivermectin or albendazole
    • In areas endemic for onchocerca or Loa Loa, ivermectin with albendazole as single dose yearly
  • Doxycycline
    • eliminates mf gradually by killing Wohlbachia, avoids advers inflammatory events, avoids inflammatory nodules seen with DEC/IVM induced ‘rapid’ death of adult worms
  • Combi treatments
    • 3 wk doxy then ivermectin + albendazole sterilizes LF parasites and clears MF but doesn’t kill adults
    • 3 wk doxy then DEC 90% kill adults
  • Adverse rxns pos associated with prevalence and intensity of microfilaria
    • headache, body ache, fever, dizziness, reduced appetite, malaise, nausea, urticaria, vomiting, itching, wheezing, bronchial asthma
  • Local rxns: scrotal nodules, lymphadenitis, funiculitis, epididimitis, lymphangitis, orchalgia, abscesses, ulcers transient lymphedema
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6
Q

Tropical Pulmonary Eosinophilia

A
  • hypersensitivity response to Wucheria mf in lungs
  • mf absent from blood but may be present in lung bx
  • adults on USS
  • nocturnal cough and wheeze
  • enlarged liver, spleen, nodules
  • CXR: diffuse miliary shadows
  • reduced res vol, vital and lung cap
  • untreated progress to irreversible fibrosis
  • lab: hypereosinophilia, high mf titres (pos Ag test)
  • Rx: Standard DEC for 3 wk
  • NEW tx: doxy 200 mg daily x 4 wk + IVM
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7
Q

Lifecycle Onchocerca Volvulus

A
  1. blackfly (Simulium) takes a blood meal, L3 larvae enter bite wound
  2. subcut human tissues to form a
  3. subuct nodule
  4. adults produce unsheathed microfilariae that typically are found in skin and lymphatics, also occ in per blood, urine, sput (forget this)
  5. Simulium takes blood meal
  6. mf penetrate bf midgut and migrate to thoracic muscles
  7. L1 larva
  8. L3 larva
  9. migrate to head and proboscis and waits
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8
Q

Onchocerca pathology

A
  • host infl response to dead, dying tissue
  • eosinophils lead to cellular proteins to ct damage
  • adult worms releas substances which inhibit host immune response
  • Wolbachia: mf death leads to releas of bacterial mediators that trigger the innate immune system leading to clinical effects of the disease
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9
Q

Onchocerca: clinical

A
  • itch to excoriation to healing with hyperpigmentation
  • mp rash
  • deg skin changes, loss of elasticity, wrinkling, hanging groin
  • depigmentation leading to leopard skin appearance
  • Sowda (Yemen, N. Sudan, W. Africa) - localized chronic pap dermatitis leading to hyper immune response, mf scarce
  • nodules - sub, painless, most obvious over bony prominences, pressure poing
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10
Q
    • Skin Snips
      • Where should they be taken?
        • in Africa?
        • in Cent America?
  • What other procedures may be useful?
A
  • Skin snips:
    • Africa: calf, thigh, hip, iliac crest
    • C. america: outer canthus of eye, shoulder
  • otherwise, slit lamp exam may reveal mf in anterior chamber
  • Mazzoti test (if skin snips neg): low dose 6 mg DEC patch leading to intense itching no longer recommended
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11
Q

Diagnostic tests for Onchocerca

A
  • rapid format ab card tes
  • elisa
  • dna probes
  • ab detection useful for screening populations
  • PCR and Ag detection in serum and urine potentially more useful for diagnosing active infection in individuals and for monitoring the success of therapy
  • Rapid diagnostic tests
    • Luciferase immunoprecipitation assay (LIPS)
    • cocktail of 4 O. volvulus ag
    • 100% sens and spec using rapid 15 min format, can dx from W. bancrofti, L.loa, Strongyloides
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12
Q

Onchocerca tx

A
  • ivermectin: single dose clears mf for sev mo but does not kill adults.
    • rpt q 6-12 mo x 12+ yr until adults die
    • other than in very heavy infections usually no Mazotti rx
  • nodulectomy for head nodules only
  • suramin and DEC no longer rec because toxic
  • doxycycline sterilises )+/- kills adult worms, reduces high mf loads and reduces side effects of others
    • dose 200 mg daily x 6 wks + 2 doses ivm
  • moxidectin romising, in trials
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13
Q

Loa Loa

Clinical

Early

Complications

A
  • urticaria, pruritis, arthralgia and malaise
  • transient, migratory angioedema (Calabar swellings) occur mainly on extremities wher trauma to migrating adult worm causes local inflammatory rx
  • subconjunctival migration cause pain and inflammation, may be removed under local
  • Other complications:
    • proteinuria up to 30%, hematuria, esp with killing off mf
    • neurological comp, less common, esp meningoencephalitis
    • rare: pulmonary infiltrates, pleural effusions, arthritis, lymphangitis, hydrocele
    • Hypereosinophilia and loa loa implicated in etiology of endomyocardial fibrosis
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14
Q

Loa Loa Dx

A
  • history suggestiv, or ‘eye worm’
  • dead calcifie worms on xray
  • microfiliaremia peaks btw 10:00 and 15:00 hrs
  • Giemsa or Wright thick films or using concentration technique
  • assessing mf load useful in determining tx
  • serological tests available but cross react with other parasites
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15
Q

Loa Loa Tx

A
  • if not high mf load, DEC 2 mg/kg tid x 7-10 days commonly used
  • rpt at intervals of 2-3 mo if remains sx
  • Ivermecting as single dose prior to tx with DEC reduces likelihood of Mazzotti rxn
  • CAUTION
    • in high MF loads, tx wiith DEC or ivermectin may precipitate meningoencephalitis or renal failure due to massive release of ag from dying mf
    • plasmapherese has been used prior to DEC under steroid cover
    • Albendazole 200 mg bid x 3 wks causes gradual reduction in mf, usually without serious a/e - may become preferred strategy in pts with high mf load
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16
Q

General tx of Filarial Infections

Which for which?

A
17
Q

Filiarisis Summary Treatment

Mass Drug Admin

Africa vs elsewhere

Individual drug admin

morbidity tx and control

A
18
Q

Oncho Tx Summary

Mass Drug Admin

Africa vs elsewhere

Individual tx

morbidity control

A
19
Q

Guinea Worm Lifecycle

A
  1. Human drinks unfiltered water containing copepods with L3 Larvae
  2. Larvae released when copepods die, larvae penetrate hosts stomach and intestinal wall, mature and reproduce
  3. fertilized female migrates to surface of skin and begins to emerge one year after infection, causes a blister and releases larvae
  4. L1 larvae released into water from emerging female worm
  5. L1 larvae consumed by copepod
  6. Larvae undergoes 2 molts in copepod and becomes L3 larvae, at which point human drinks the copepod
20
Q

Guinea Worms complications

A
  • migrating adult worms may penetrate and die inother tissues, including spinal cord, peritoneal cavity, pancreas, pericardium and lung causing sx due to focal inflammation
  • ulcer can become secondarily infected or fail to heal
21
Q
  • Guinea Worm Treatment
A
  • ancient
  • slowly remove worm by winding around stick a little at a time
  • may take a few days
  • oral metronidazole or mebendazole may facilitate extraction
  • surgical extraction may be needed for ectopic worms
22
Q

Vectors for

  1. Filiariasis
    1. Wucheria bancrofti
    2. Brugia Malayi
  2. Onchocerciasis
  3. Loa Loa
  4. Guinea Worm
A
  1. Filiariasis
    1. Wucheria
      1. Anopheles W Africa
      2. Culex quinquefasciatus: E Africa, SA, Asia (urban mosquito)
      3. Mansonia in Papua New Guinea
      4. Aedes for diurnally periodic form in Asia and nocturnally subperiodic form in Thailand
    2. Brugia is transmitted by various Mansonia, Anopheles, Aedes vectors
  2. Onchocerciasis
    1. Blackfly Simulium
  3. Loa Loa
    1. Deer Fly Chrysops
  4. Guinea Worm
    1. Cyclops copepod