NTD's Flashcards
1
Q
Review Lifecycle of W. Bancrofti
A
- mosquito takes blood meal, L3 larvae enter skin
- migrate via lymphatics, usually settling in groin and develop into adults
- adults produced sheathed microfilaria
- mosquito ingests microfilaria in blood meal
- mf sheds sheat to midgut and migrate to thoracic muscles
- L1 larva
- L3 Larva
- migrate to head and proboscis and enter and so on
2
Q
How does Filiariasis present clinically?
A
- acute filarial fever without lymphadenitis
- 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
- acute dermatolymphangiolymphadenitis
- secondary infection severe, edemal
- Acute Filarial Lymphangitis with death of adult worm, either spont or after treatment
- usually mild, rarely causes residual lymphoma
- Chronic lymphatic filiariasis
- may develop months to years later, with or without acut sx
- recurrent infections, often strep, may lead to GN
- Other presentations
- hydrocele
- lymph scrotum
- acute epididimitis
- funiculitis - inflammation of spermatic cord
- cyluria, chylous diarrhea, chylous ascites, due to rupture of dilated lymphatics
- monoarthritis, glomerulonephritis
- Don’t forget social consequences
- stigma, employment, maritability
3
Q
Diff dx filiariasis
- filarial fever
- variable groin glands
- filarial glandular enlargement
- filarial orchitis, funiculitis, hydrocele
- chyluria
- elephantiasis
A
- filiarial fever: malaria, other acute or recurrent fevers, acute bacterial lymphangitis
- groin mass: hernias, hanging groin of onchocerciasis
- fil gland enlargement: chronic infection, tb, lymphogranuloma inguinale, reticuloses (var mycosis fungoides), lymphoma, leukemia
- fil orchitis, funiculitis, hydrocele - acute infection, tb, s. hematobium, “surgical”
- chyluria: other causes lymphatic obstn eg tb
- elephantiasis: chronic siderosilicosis - particles of sand from barefoot blocks them, milroy’s disease - congenital, lepromatous leprosy, repeated strep infections feet
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
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
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
7
Q
Lifecycle Onchocerca Volvulus
A
- blackfly (Simulium) takes a blood meal, L3 larvae enter bite wound
- subcut human tissues to form a
- subuct nodule
- adults produce unsheathed microfilariae that typically are found in skin and lymphatics, also occ in per blood, urine, sput (forget this)
- Simulium takes blood meal
- mf penetrate bf midgut and migrate to thoracic muscles
- L1 larva
- L3 larva
- migrate to head and proboscis and waits
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
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
10
Q
- Skin Snips
- Where should they be taken?
- in Africa?
- in Cent America?
- Where should they be taken?
- Skin Snips
- 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
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
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
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
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
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
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
- Human drinks unfiltered water containing copepods with L3 Larvae
- Larvae released when copepods die, larvae penetrate hosts stomach and intestinal wall, mature and reproduce
- fertilized female migrates to surface of skin and begins to emerge one year after infection, causes a blister and releases larvae
- L1 larvae released into water from emerging female worm
- L1 larvae consumed by copepod
- Larvae undergoes 2 molts in copepod and becomes L3 larvae, at which point human drinks the copepod
