Filarial Parasites Flashcards by Shazebelle Shaun

A special test, performed when skin snips are negative of microfilaria but clinical suspicion is very high

Mazzotti test

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Sheathed microfilariae with nuclei up to tail-tip

Brugia malayi
Loa loa

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Considered a Neglected Tropical Disease

Onchocerca volvulus

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Unsheathed and non-periodic microfilariae:

Mansonella perstans
Mansonella ozzardi

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Calabar swelling is also known as:

Migratory swelling

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Disease caused by Onchocerca volvulus

Onchocerciasis, Dermatitis

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Subnocturnal or more active at night time but still active during day time

Brugia malayi

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Microfilaria Morphology:
* No hyaline sheath
* Body curve is regular and slightly twisted
* Large cephalic space
* Fine and mostly separated body nuclei
* Nuclei doesn’t reach the pointed tip

Mansonella ozzardi

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Caused by obstruction of lymph vessels

Elephantiasis/Lymphatic filariasis

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Vector of Loa loa

Chrysops (deer flies)

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Detects filarial antigens by amplification of
DNA; sensitive test

Polymerase Chain Reaction (PCR)

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Characterized by painful lesions that even the touch of wind or air is already painful

Adenolymphangitis (ADL) or Dermatolymphangioadenitis (DLA)

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Wuchereria bancrofti is also known as:

Bancroft’s filaria

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Intermediate host of Loa loa

Chrysops

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Microfilaria Morphology
* No hyaline sheath
* Tail usually curved; “Shepherd’s crook”
* Large cephalic space
* Body nuclei fine and mostly separated
* Nuclei reaches the tip
* No microfilarial periodicity

Mansonella streptocerca

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Vector of M. perstans

Cullicoides (midge)

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Microfilaria in Blood:

Wuchereria bancrofti
Brugia malayi and Brugia timori
Mansonella perstans
Mansonella ozzardi
Loa loa

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Mosquitoes that can transmit lymphatic filariasis:

Anophelen and culicine mosquitoes

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Nocturnal or active in the circulation during night time
(8pm - 4am)

Wuchereria bancrofti

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Intermediate host of Wuchereria bancrofti:

Culex, Anopheles, Aedes

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Body curves: Regular, often form loops

Mansonella perstans

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Not seen in blood film preparation because they are commonly seen in the lymphatics

Adult worms

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Several curvatures characterized as regular and curvy

Wuchereria bancrofti

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Symmetry: Unilateral/Asymmetric

Brugia malayi

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Definitive host of Brugia malayi

Human, Cats, Dogs, Monkeys

Periodicity of Loa loa

Diurnal | seen during daytime, common during rainy days

Characteristic lizard skin/leopard skin due to depigmentation

Onchocerciasis

Burden: Sub-Saharan Africa

Onchocerca volvulus

Sheathed mocrofilariae tail-tip free from nuclei:

Wuchereria bancrofti

Disease caused by M. perstans

Ugandan eye worm

Nuclear arrangement: column of nuclei is in 2 rows (indistinct/irregularly arranged) with 2 nuclei at the tip of the tail

Brugia malayi

Infective stage of O. volvulus

L3 larva

Angular curvature with secondary kinks (kinky)

Brugia malayi

Localization: Above the knee

Wuchereria bancrofti

Incidence: Equal for adult and children

Wuchereria bancrofti

Tail tapered and bluntly rounded, bent in “shepherd’s crook” shape

Mansonella streptocerca

Gold standard for Diagnosing Lymphatic Parasites

Microscopy

Formerly called Dipetalonema perstans

Mansonella perstans

Stage where patient is clinically well or shows no sign and symptoms, howevere, when diagnostics tests are done, thousands/millions of microfilariae are found in the PBS and adult worms in the lymphatics of the patient

Asymptomatic stage

Intermediate host of B. malayi

Mansonia bonis/uniformis

Microfilariae enclosed in a hyaline sheath with a dark staining nuclei on central axis

Wuchereria bancrofti and Brugia malayi

Intermediate host of Onchocerca volvulus

Simulium

Pitting edema to non-pitting edena with repeated acute inflammatory episodes

Chronic stage

Drug of Choice for W. bancrofti and B. malayi

Diethylcarbamazine

Common in Africa and South America

Mansonella perstans

Disease caused by Loa loa:

Loiasis and Calabar swelling

The adult worms of this parasite resembles those of Wuchereria bancrofti but are smaller

Brugia malayi

Tail tapered to a point

Onchocerca volvulus

The enlarged parts harden with loss of skin elasticity and fibrosis producing Elephantiasis

Chronic stage

Vectors of Mansonella ozzardi:

Cullicoides (midge) and Simulium (black fly)

Drug of choice for M. ozzardi:

Ivermectin

Knott's technique

* Citrated blood + formalin * Centrifugation * Yield increases

Inflammation of lymph nodes and skin, reaction of the body to dead adult worms

Adenolymphangitis (ADL) or Dermatolymphangioadenitis (DLA)

Distribution: Tropics, India

Wuchereria bancrofti

Microfilariae that is found both in blood and skin:

Mansonella ozzardi

Cellular reaction and fibrous hyperlapsia in the lower extremeties or any involved area

Chronic stage

Sheathed and periodic microfilariae:

* Wuchereria bancrofti * Brugia malayi * Loa loa

Two discrete nuclei in tip of the tail

Brugia malayi

Diagnosis for M. streptocerca

Demonstration of the microfilariae in skin snips

Infective stage of Loa loa:

L3 larva

Definitive host of Wuchereria bancrofti

Man

Mansonella perstans is formerly called as:

Dipetalonema perstans

Seen in patients with down regulated immune system or "endemic normals"

Asymptomatic stage

Possible reasons for patients who clinically manifest with Elephantiasis but no microfilariae are seen in the blood:

* Low intensity of infection * Presence of dead worms * Obstructed lymphatics

Unsheathed microfilariae with nuclei up to tail-tip:

* Mansonella perstans * Mansonella streptocerca

Microfilaria Morphology: * No hyaline sheath * Large cephalic space * Body nuclei tend to overlap * Nucleus reaches the tip of the rounded tail

Mansonella perstans

Parasite is absorbed and replaced by granulation tissue

Chronic stage

Microfilariae found in skin:

* Onchocerca volvulus * Mansonella streptocerca * Mansonella ozzardi

Drug of choice for Mansonella streptocerca

Ivermectin

Brugia malayi is also known as:

Malayan filariasis

Person who harbour the parasite antigen which are the different parts of the parasite, like the sheath, but does not harbour the microfilariae itself

Asymptomatic

Diagnostic stage of Loa loa:

Microfilaria, sometimes the adult worm

Stage where early manifestations are fever with or without involvement of lymph glands (lymphadenitis) and recurrent attacks of funiculitis, swelling and redness of the arms and legs, Adenolymphangitis (ADL) or Dermatolymphangioadenitis (DLA)

Acute stage

Epidemiology: Central and South America, some islands of west indies

Mansonella ozzardi

Unsheathed microfilariae tail-tip free from nuclei:

* Mansonella ozzardi * Onchocerca volvulus

African eye worm

Loa loa

Causes River Blindness

Onchocerca volvulus

Vector (rural) of Wuchereria bancrofti:

Anopheles

Drug of choice for O. volvulus

* Ivermectin * Antihistamine (for pruritis)

Treatment for Loa loa:

* Surgery * Chemotherapy * Diethylcarbamazine (for microfilaria and adult worm) * Albendazole (resistant to DEC against adult worms)

Tail long and slender

Mansonella ozzardi

Vector of Mansonella streptocerca

Cullicoides (midge)

Risk of infection for Loa loa:

* Number of bites * Number of infected deer flies * Length of stay in the area

Distribution: Southern Asia

Brugia malayi

Localization: Below the knee

Brugia malayi

Most common filarial manifestation

Elephantiasis/Lymphatic filariasis

Stage where it develops slowly following years of continuous infection

Chronic stage

Diagnosis for O. volvulus

* Demonstration of the microfilariae in skin snips * Demonstration of the adult worm in the eye

Diseases caused by M. streptocerca

* usually asymptomatic * Cutaneous edema * Elephantiasis

Diagnosis for Loa loa:

* PBS * Demonstration of adult worm * Knott's technique * Filtration

Important reservoir host of Brugia malayi:

Cats

Microfilaria will mature to L3 after 3 molts

Loa loa

Nuclei arrangement: Column of 2-3 rows with no terminal nuclei at the tip

Wuchereria bancrofti

Incidence: More seen in adults than in children

Brugia malayi

Common in Ghana, Nigeria, Congo

Mansonella streptocerca

Asymptomatic in endemic areas, symptomatic to travelers

Loiasis

Vector of Onchocerca volvulus:

Blackfly Simulium

Infective stage of Mansonella perstans

L3 larva

Vector of Brugia malayi

Mansonia bonnae/uniformis

Development of Loa loa to adult from microfilaria

1 year

Reveals the presence of microfilariae

Examination of Blood film

Microfilariae found in blood:

* Wuchereria bancrofti * Brugia malayi * Brugia timori * Loa loa * Mansonella perstans * Mansonella ozzardi

Vector (urban) of Wuchereria bancrofti:

Culex

Symmetry: Bilateral

Wuchereria bancrofti

Tend to stay in the lower extremeties, could be in the lymph nodes and not much on the upper extremeties

Elephantiasis/Lymphatic filariasis