Filariasis Flashcards
Infective stage for W.Bancrofti/B.Malayi?
L3 larvae
Name the vector for W.Bancrofti/B.Malayi
Aedes agypti, anopheles, manonia, culex - a mix of night or day biting mosquitos
Which stage of the lifecycle do mosquitos take up during a blood meal in W.Bancrofti/B.Malayi?
pre-L1 larvae - microfilaria
Where do L3 larvae mature to adults in the human body (W.Bancrofti/B.Malayi)?
Lymphatics
What are the symptoms of W.Bancrofti/B.Malayi?
Lymphadenitis, lymphedema, fever, hydrocele
Chyluria - renal lymphatics get blocked - get chyle in urine
What causes tropical pulmonary eosinophilia?
W.Bancrofti/B.Malayi
Microfilariae released into blood from mating adult worms in lymph nodes - IgE response
Where in the world is lymphatic filariasis?
What are the symptoms of tropical pulmonary eosinophila?
Presents with paroxysmal nocturnal asthma + pulmonary infiltrates + eosinophilia >3000/ml, raised IgE, rapid response to Rx
bilateral lower lobe interstitial disease. Mostly young males in India.
What are the key clinical differences between B.Malayi to W.Bankrofti?
Bankrofti - more common (90%) vs Malayi 10%
Malayi - Elephantiasis usually
lower leg, Cold filarial abscesses
What other tests can you do for W.Bankrofti and what would you see?
Ultrasound
”Filaria dance sign”
Can also see adult worms
Lymphoscintigraphy to see extent of damage to anatomy
Investigation of choice in lymphatic filariasis?
Blood sample and smear to look for microfilariae
Taken night time - microfilariae circulate at night!
Drug of choice for lymphatic filariasis?
DEC followed by 6 weeks of doxy
Diethylcarbamazine
Single dose is microfilaricidal but can be given longer to kill adult
Alternatives to Rx of lymphatic filariasis in control programmes?
Single dose of ivermectin or albendazole - microfilaricidal therefore prevent transmission
Another alternative Rx for lymphatic filariasis?
Kill the Wolbachia bacteria which allows the worm to exist
What must you check before Rx?
No onchocerciasis
What is the mass Rx strategy?
IDA
Ivermectin
DEC
Albendazole
Alternative tests for lymphatic filariasis species?
Serology
IgG or antigen test
What is the vector for onchocerca volvulus?
Simulium fly
Infective stage for onchocerca volvulus?
L3 larvae
Where do larvae develop into adults in onchocerca volvulus?
Subcutaneous nodules
What is different about onchocerca volvulus to W.Bankrofti and B.Malayi?
Adults develop in subcut nodules and migrate through SKIN AND EYE not blood
What are the symptoms of O.Volvulus?
-Pruritus, dermatitis
-Punctate and sclerosing keratitis, blindness
-Encapsulated nodules in skin
- leopard skin- hypopigmentation
Which species causes ‘river blindness’?
onchocerca volvulus
Where do the Simulium flies breed?
Fast flowing rivers
∆∆ onchocercaisis
Furuncular myiasis
Subcut cysticercosis
What causes this in severe cases?
O.Volvulus
Leopard skin, severe dermatitis
Skin biopsy of a patient with dermatitis. Which filarial worm is this?
O.Volvulus
No sheath, nuclei not to the end of the tail
What is nocturnal periodicity?
Filarial worms, the microfilariae only circulate in blood at night
What is Sowda?
Localised oncodermatitis
Hyperimmune response to microfilariae
What is the classic presentation of onchcerca in a returning expat?
Lightly infected skin, no eye disease
What investigations can be done for O.Volvulus?
Skin snip
PCR is GOLD STANDARD
Mazotti test is an option
Eye exam
Bx of nodule
What is the Mazotti test?
Administration of small dose of DEC and get significant exacerbation of itching due to dying larvae?
What is the Rx of O.Volvulus mono infection?
1 week of ivermectin
6 weeks of doxycycline
1 dose of ivermectin
In that order
What causes the mazotti reaction?
Wolbachia present in O. volvulus cause inflammation - do not give DEC for this reason
What is the purpose of ivermectin and doxy in Rx of onchocerca?
Doxy - sterilises adult females - does not kill microfilariae
Ivermectin kills microfilariae
What is used for mass chemotherapy?
Ivermectin (microfilarcidal)
Where in the Americas is onchocerca volvulus still a problem?
Venezuela
What is the vector for Loa Loa?
Chrysops
Injects L3
What is the classical presentation of Loa Loa?
Transient subcutaneous nodules
Urticaria
Migrate through conjunctiva - irritation in eye
What is different about the pattern of microfilarial release in Loa Loa?
Microfilaria released in day not night!
Optimal time to test - 4pm
Where do Chrysops breed?
Mud below rainforest canopy
What is a calabar swelling?
Transient itchy nodules caused from Loa Loa
How do you test for Loa Loa?
Blood microfilarial smear
Adults live subcutaneously
Microfilaria in blood
How do you treat Loa Loa?
Depends on microfilarial count and mono infection or co infection
How do you treat mono infection Loa Loa?
<2500 microfilaria/ml
DEC
Not if have onchocerca
>2500 apheresis and expert input or albendazole until <2500
Then DEC
How do you Rx Loa and O.Volvulus?
Onchocerca Rx first - ivermectin single dose
Wait 6-12 months
Rx LoaLoa with DEC
Why do you not give DEC if microfilarial count is very high?
In patients with >2,500 Loa loa microfilaria/ml of
blood, treatment of onchocerciasis with
Ivermectin or Moxidectin can result in facilitation
of Loa loa entry into the CNS with severe
encephalopathy and even death.
How do you Rx LF and Loa?
Both are Rx with DEC however same rules apply re: microfilarial count of Loa
How do you Rx Onchocerca and LF?
Onchocerca Rx first - ivermectin single dose
Wait 1 month
Rx for LF: Give DEC
What is this?
Sheath
Nuclei not to the end
Therefore W.Bankrofti
What is this? Skin snip.
Unsheathed
Nuclei not to the end
Found in skin therefore O.Volvulus
What is this?
Sheath
Nuclei to the end (low)
Therefore Loa Loa
What is this?
Sheath
Terminal nucleus
Therefore B.Malayi
What is this?
No sheath
Nuclei to the end
Therefore Mansonella Persians
What is this? Skin Bx.
No sheath
Hooked tail
Nuclei to the end
Therefore M.Streptocerca
What is this? Blood smear
No sheath
Nuclei not to the end of the tail
Therefore M.Ozzardi (wizard of Oz does not exist)
What is this?
W.Bankrofti
What other test can you do for W.Bankrofti?
Circulating antigen test using ELISA
Also used in rapid test
Secreted by adult worm
Not for B.Malayi
What is the Biplex test?
Rapid test for W.Bankrofti and Onchocerca
What is this? Tissue biopsy?
O.Volvulus
What is this?
B.Malayi
What is this?
M.perstans
What is this?
Loa Loa
Elongated nuclei pathopneumonic
What is this?
W.Bankrofti
What is this?
M.Streptocerca
What is this?
W.Bankrofti
What is this?
Loa Loa
What is this?
B.Malayi