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Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt > Filarial Nematodes - Onchocerciasis, Filariasis, Loiasis > Flashcards

Filarial Nematodes - Onchocerciasis, Filariasis, Loiasis Flashcards

1
Q

Why are Tetracyclines effective against helminths? Eg onchocerciasis and filarisis
How long rx?

A

They depend on intracellular bacteria - Wolbachia for their development and fertility
- Wolbachia are sensitive to Tetracyclines

Requires 6 weeks of treatment

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2
Q

Onchocerciasis size of adult worm? Full name?
Basic life cycle? Key vector

A
  • 40cm long and can live 15 years
    -Onchocerca volvulus
  • lives in sub cut tissue and produces microfilariae (350um)
  • These are taken up by a blackfly called Simulium
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3
Q

Where do simulium flies live?

A

Fast flowing water -> get Onchocerasis mostly in people living near rivers

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4
Q

Onchocerciasis 3 key parts of sx

A
  • Cutaneous itchy papular rash (leopard skin)
  • Sub cutaneous nodules
  • Eye disease (river blindness)
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5
Q

How does Onchocerasis present on the skin? How does it progress? Often mistaken for?

A
  • Acute/chronic papular onchodermatitis
  • Itchy, hyperpigmented papules
  • Can progress to atrophy and depigmentation of skin which leads to excessive wrinkles (or ‘hanging groin’ appearance)
  • also called leopards skin
  • Often initially mistaken for scabies
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6
Q

What causes the subcutaneous nodules in Onchocerciasis

A

Adult worms getting trapped and becoming enclosed in fibrous tissue

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7
Q

Eye disease in Onchocerasis (2 types)

A
  • Anterior keratitis ‘snow flake’ opacity visible. This pannus may continue to sclerose and cover cornea
  • Posterior Eye- may present with widespread chorioretinitis with pigment changes. Sometimes accompanied by optic atrophy
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8
Q

Diagnosis Onchocerasis? What is the rapid diagnostic test called?

A
  • Skin snip / biopsy for microfilariae (insensitive)
  • Can use PCR - rare and expensive
  • Rapid diagnostic test LIPS (Luciferase immunoprecipitation system) assay. This can also distinguish between O volvulus, W Bancrofti, l loa and stronglyotides.
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9
Q

Onchocerciasis rx?

A

Doxy for 6 weeks then single dose ivermectin

Ivermectin - can be used for mass chemo
- Doxy can be used to target Wolbachia AND also kills adults if 6 week course
- Ivermectin Doesn’t work well on adult worms so often need multiple doses over many years

  • (Moxidectin is a potent version of ivermectin)
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10
Q

High load loa microfilaraemia rx eg >2500Mf/ml? Why not ivermectin

A

Either Albendazole for 3 weeks then DEC
Or Apheresis prior to DEC

Ivermectin -> facilitates loa entry into CNS

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11
Q

How do most Onchocerasis eradication programs work

A

Mass chemo with ivermectin

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12
Q

Cause of lymphatic filariasis? How big do they get? Vector ? What is required for its sexual reproduction?

A
  • Wuchereria bancrofti. Males 4cm females 10cm and release 10000 microfilariae daily
  • Mosquito - various types but key one is culex quinquefasciatus which breads in drains / polluted water
  • Wolbachia bacteria
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13
Q

Filariasis key sx

A
  • Often get fever
  • Acute filarial lymphangitis (death of worm and inflammatory response to it) . Inflam nodule which may form an abscess
  • Elephantiasis
  • Often get bacterial infections in lymphatic due to slow flow / breaks in skin
  • Often epididymitis / hydrocoele etc
  • chyluria
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14
Q

Filariasis dx?

A
  • immunochromatographic card test (ICT) - now first line
    [Rapid diagnostic test]
  • ELISA or PCR
  • Peripheral thick blood films with Giemsa stain. Works best in middle of night
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15
Q

Which form of filariasis in Asia with milder symptoms and only rare elaphantitis

A

Brugia Malayi

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16
Q

Management of filariasis if single diagnosis? If confection with Onchocerasis?

A

Diethylcarbamazine 6mg/kg for 12 days
- AND 6 weeks Doxy

If Onchocerciasis too, give Ivermectin
- then DEC 4 weeks later

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17
Q

Filariasis control strategies

A
  • Mass drug administration (albendazoe / ivermectin / diethlycarbamazine
  • Morbidity management + disability prevention
  • Vector control - mosquito nets and treatment of enclosed water in towns with polystyrene beads prevents mosquitos breading
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18
Q

Loasis ‘the eye worm’ is transmitted by? Size of adult worm?

A
  • Chrysops - Red flys from tropical forests in Africa
  • 3-7cm
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19
Q

What is the name for trauma caused by migrating loa in extremities

A

Calabar swelling

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20
Q

Loasis dx

A
  • May complain of worms in white of eye
  • Thick blood films with Giesma staining
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21
Q

Loasis rx ? How to prevent mazzoti reaction? What to do if high microfilariae load >2500Mf/m

A
  • Diethycarbamazine 2mg/kg for 7-10 days
  • Add ivermectin 150ug/kg as a single dose prior to treatment to help prevent mazzoti reaction
  • High Mf load - course of albendazole prior to Diethylcarbamazine
    OR if rich -> pre-treatment apheresis
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22
Q

Treatment of filarial infection then several days later develops fever urticaria, swollen tender lymph nodes ans appears shocked with abdo pain and arthralgia? Key drug?

A

Mazotti reaction - most commonly after DEC (but could be other microfilarial chemo)

Occur within 7 days

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23
Q

Lymphatic filariasis life cycle

A

L3 lava injected by culex (usually)
Male and female mate in lymphatic
Produce microfiliarae L1 which would not infect humans.
mosquito takes up
Matures into L2 then L3 in mosquito

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24
Q

Differential to lymphatic filariasis that is caused by silica

A

Podoconiosis - disease will be bilateral

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25
Q

Name 3 Ddx with firm skin nodules

A

Cutaneous Cysticercosis
Bot fly
Abscess
Onchocerciasis

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26
Q

What time best for loa loa blood film

A

4pm

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27
Q

Lymphatic fil + oncho rx?

A

First treat the onchocerciasis with Ivermectin or Moxidectin 8 mg po
as single dose;

wait one month and then give DEC for lymphatic filariasis

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28
Q

Lymph + loa rx

A

If < 2,500 Loa loa microfilaria/mL, Diethylcarbamazine 21 days.

If > 2,500 Loa loa microfilaria/mL, refer to expert center for possible pre-treatment apheresis.
* Or give Ivermectin 150 µg/kg po once followed by single dose of DEC 6 mg/kg

> 20,000 - Doxy only

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29
Q

2 bugs that cause lymphatic filariasis

A

Wuchereria bancrofti 90%

Brugia malayi 10% - only causes below knee sx eg cold abscesses but no hydrocoele.

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30
Q

What causes chyluria in lymphatic filariasis

A

Anastomosis between abdo lymphatic and renal collecting system

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31
Q

Tropical pulmonary eosinophilia 90% in who. Key sx

A

Young males 90%
Wheeze - ONLY at night classically

32
Q

US lymphatic filariasis key finding

A

Filiarial dance sign in scrotal lymphatics

33
Q

Why not DEC for lymphatic filariasis control program

A

Side effects + bad reactions if coinfection eg oncho
Usually use ivermectin instead

34
Q

Why Doxy 4 weeks then ivermectin if lymphatic filariasis confection with Onchocerasis rather than diethlycarbamazine?

A

DEC + Oncho -> inflammation -> Risk of blindness if microfilariae in eye

35
Q

What is mazotti test

A

Give small amount of DEC in Onchocerasis

Become intensity itchy

[Dangerous as may cause blindness]

36
Q

2 cause of lymphatic filariasis

A

Wuchereria bancrofti 90%

Brugia malayi 10% - only causes below knee sx eg cold abscesses but no

37
Q

2 cause of lymphatic filariasis

A

Wuchereria bancrofti 90%

Brugia malayi 10% - only causes below knee sx eg cold abscesses but no

38
Q

What are options for lymphatic filariasis? Which eradicate macro vs microfilarial. Which for individual cases?

A

DEC + doxy
Drugs of choice individual cases
aggressive macrofilaricidal regimen; 20% eradication
Single dose is microfilaricidal

Ivermectin
Single dose microfilaricidal; control programs
Not macrofilaricidal

Albendazole
Single dose micro and somewhat macrofilaricial

DEC/ALB combination
Aggressive Rx for 1 week then repeat annually
80% antigen clearance rate at 4 years

39
Q

Oncho + loa rx

A

Ivermectin first (for oncho)
Then DEC for loa loa

40
Q

Loa rx

A
  1. Screen for others first and if mono infection
  2. Check loa load

<2500microfilaria/ml
Diethylcarbamazine for 21 days

> 2500microfilaria/ml
Refer for apheresis prior to therapy
OR albendazole for 3weeks then DEC

41
Q

Oncho monoinfection Rx

A

Doxy for 6 weeks
then single dose ivermectin

42
Q

What abx contraindicated in oncho

A

DEC

43
Q

loa + oncho infection rx

A

Oncho rx first with Ivermectin IF loa <2500microfil/ml

wait 6 months then treat loa with Diethylcarbamazine

If >2500mf/ml requires pre treatment apheriesis

44
Q

Lymphatic filariasis mono infection rx

A

diethylcarbamazine single dose
6 weeks doxy

45
Q

Lymphatic filariasis + oncho rx

A

1st treat oncho with ivermectin /moxidectin
Wait 1 month then DEC for Lymphatic filariasis

46
Q

Lymphatic filariasis + loa rx

A

If <2500 loa microfil/ml
Diethylcarbamazine for 21 days

If >2500 may need treatment apheresis
OR ivermectin
THEN Diethylcarbamazine

47
Q

Lymphatic filariasis + >20,000mf/ml of loa rx

A

Doxycycline only

48
Q

Filariasis life cycle

A
49
Q

Onchoceraisis life cycle

A
50
Q

Loa loa life cycle

A
51
Q

What disease might I give you?

A

Chrysops
vector of Loa loa

52
Q
A

A wuchereria - Sheath. no nucleus at the end. Head end nuclei really obvious

B brugia - Sheath, has a sub terminal amd terminal nucleus

C o volvulus - Skin snip nuclei don’t get to end

D loa loa - Sheath, nuclei are large and longer.

E m Perstans - No sheath nuclei to end

F m streptocerca -Skin nuclei to end. Tail almost always has a J shape

G m ozzardi - No sheath nuclei not to end (ONLY filaria in Peru)

53
Q
A

B Malayi

54
Q

Best test for bancrofti

A

Rapid Card test

55
Q

Which 2 microfilariae in the skin? Differentiate

A

O volvulus - nuclei don’t get to end
[0 nuclei at the end]

Mansonella streptocerca- nuclei to end. Tail almost always has a J shape
[cerca - like onchocerca = both in skin]

56
Q

Which 3 blood born microfiliarae have a sheath? Differentiate them?

A

Wuchereria bancrofti - no nucleus at the end. Head end nuclei really obvious

Brugia malayi - has a sub terminal amd terminal nucleus (big gap between them)

Loa loa - nuclei are large and longer. Head nuclei not really obvious

57
Q

Which 2 blood born microfiliarae don’t have a sheath? Differentiate

A

Mansonella Perstans - nuclei to end

Mansonella ozzardi - nuclei not to end and not very distinct
-Only filaria in Peru
-[Ozzardi O nuclei at end]

58
Q

Which filiarial infection best blood film at night?
4pm?

A

Wuchereria bancrofti at night

loa loa at 4pm

59
Q

Which filiarial has a circulating antigen test? What is important about this?

A

Wuchereria bancrofti
Tells you there is a viable adult worm not just microfilariae

ELISA or rapid card/strip test

60
Q
A

Wuchereria bancrofti - Sheath no nucleus at the end. Head end nuclei really obvious

61
Q
A

Wuchereria bancrofti - Sheath no nucleus at the end. Head end nuclei really obvious

62
Q
A

Wuchereria bancrofti - Sheath no nucleus at the end. Head end nuclei really obvious

63
Q
A

Brugia malayi - Sheath - has a sub terminal amd terminal nucleus (big gap between them)

64
Q
A

Brugia malayi - has a sub terminal amd terminal nucleus (big gap between them)

65
Q
A

Loa loa - Sheath . nuclei are large and longer. Head nuclei not really obvious

66
Q
A

Loa loa - Sheath . nuclei are large and longer. Head nuclei not really obvious

67
Q
A

Loa loa - Sheath . nuclei are large and longer. Head nuclei not really obvious

68
Q
A

O. volvulus in a subcutaneous nodule

69
Q
A

O. volvulus in a subcutaneous nodule

70
Q
A

O. volvulus in a subcutaneous nodule

71
Q

Skin

A

Onchocerca volvulus - nuclei don’t get to end

72
Q
A

Onchocerca volvulus - nuclei don’t get to end
In skin

73
Q
A

Mansonella Perstans - Blood, no sheath, nuclei to end

74
Q
A

Mansonella Perstans - Blood, no sheath, nuclei to end

75
Q

Why cant you treat loa >2500mf/ml with ivermectin

A

Facilitation of loa migration into CNS -> bad

76
Q

26 yo man with 6 yr working in Africa
ROS mild swelling in the forearms.

A

Loa loa (calabar swelling)

77
Q

Hydrocoele after living in Africa for a while

A

Wuchereria bancrofti
(Brugia malayi - only usually below knee )

Tropical medicine - All clinical images copyright Gorgas course - : Instituto de Medicina Tropical Alexander von Humboldt (26 decks)

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