LECTURE 8.3 - BLOOD NEMATODES

Adult worms (Filariae)

live in tissue or the lymphatic system and produce larvae known as microfilariae

Larvae (Microfilariae)

present in the bloodstream during a specific time period

PERIODICITY

greatest number in this period of time

Diurnal periodicity

occurring during the day

Nocturnal periodicity

occurring during the night

Sub periodic

timing of occurrences not clear-cut

Nonperiodic

No matter what’s the time, they’re always there

• Presence or absence of a Sheath

• Distribution of nuclei within the tail

Two characteristics used in speciating in the microfilariae

• WUCHERERIA BANCROFTI

• BRUGIA MALAYI

LYMPHATIC FILARIASIS

• ONCHOCERCA VOLVULUS

• LOA LOA

• MANSONELLA STREPTOCERCA

• MANSONELLA OZZARDI

SUBCUTANEOUS FILARIASIS

MANSONELLA PERSTANS

SEROUS CAVITY FILARIASIS

Lymphatic System

FILARIAE

Habitat Adult:

Blood

FILARIAE

Habitat Microfilia:

Man

FILARIAE

Final Host:

Mosquito

FILARIAE

Intermediate host:

Microfilaria

FILARIAE

Diagnostic stage:

Filariform Larva (L3)

FILARIAE

Infective Stage To Final host:

Microfilaria

FILARIAE

Infective Stage To Intermediate Host:

Bite of an infected arthropod

FILARIAE

Mode of Transmission:

• Lymphangiectasia

• Lymphagiogenesis

• Wolbachia spp

Primary mechanisms of filariasis:

Lymphangiectasia

dilation of lymph vessels due to the pre-formed saliva that enlarges to accommodate the adults that migrates to that certain vessel

Lymphagiogenesis

formation of new lymph vessels by the saliva

Wolbachia spp

endosymbiont bacterium of filarial worms (Wuchereria bancrofti, Brugia spp., Onchocerca volvulus) needed for develop

For development or pathogenesis, for viability, and fertility of these worms

Purpose of specie for filarial worms:

• Diethylcarbamazine

• Ivermectin (Adult filaria)

FILARIAE

TREATMENT:

WUCHERERIA BANCROFTI

a.k.a “Bancroftian filaria”

adults found tightly coiled in nodular dilated nests in lymph vessels and in sinuses of lymph glands

WUCHERERIA BANCROFTI

Lymphangiectasia:

Otto Edward Henry Wucherer

Identified the larval form in chylous urine

Joseph Bancroft

Identified the adult female worm

WUCHERERIA BANCROFTI

More prevalent: common in the Philippines

WUCHERERIA BANCROFTI

Most common identified species of filarial worms that infect humans

WUCHERERIA BANCROFTI

Show Nocturnal periodicity

Bancroft’s Filarial Worm

WUCHERERIA BANCROFTI

Other name:

Female mosquitoes (Aedes, Anopheles, Culex)

WUCHERERIA BANCROFTI

Vectors:

Lymphatic Filariasis

WUCHERERIA BANCROFTI

Disease/Condition:

Acute dermatolymphangioadenitis (ADLA)

common acute manifestation; defined as localized pain, lymphangitis and/or lymphadenitis

Acute filarial lymphangitis (AFL)

occurs when the adult worms die, leading to severe localized inflammation; rare manifestation, self-limited; characterized by lymphangitis that progresses distally along the lymphatic vessel producing a “Palpable cord”

Lymphedema

most common chronic manifestation and on progression, leads to elephantiasis

Elephantiasis

thickening and verrucous changes in the skin as a result of chronic leakage of fluid containing high levels of proteins (lymphedema)

Tropical Pulmonary Eosinophilia (TPE)/ Weingarten’s Syndrome

a kind of occult (hidden) filariasis; characterized by pulmonary infiltrates, peripheral eosinophilia, cough, asthmatic attacks (especially at night), and a history of prolonged residence in the tropics

Meyers Kouwenaar

microfilaria in spleen, liver and lymph node that leads to hepatosplenomegaly and lymphadenopathy

Hydrocele

a fluid filled sac in the scrotum

• Direct wet, thick and thin blood films

• Knott’s Concentration Technique

• Nucleopore filtration method

• DEC provocation test

• Serologic methods

• Antigen detection

• PCR amplification

• Ultrasonography

WUCHERERIA BANCROFTI

LABORATORY DIAGNOSIS:

Direct wet, thick and thin blood films

(stained with Giemsa) examine every portion of thick and thin films since microfilariae are often found at the thin films

Knott’s Concentration Technique

1mL of blood + 10 mL of 2% formalin → centrifuge at 500 g for 1 minute → stain with Giemsa

Nucleopore filtration method

microfilariae are trapped in the filter (nucleopore) after lysis of RBCs

DEC provocation test

includes microfilariae to appear even during day time after administration of DEC; collect samples 15 minutes to 1 hour after administration of DEC

Antigen detection

immunochromatographic methods

Ultrasonography

detect living adult worms

• Malayan Filarial Worm

• Brugian Filariasis

BRUGIA MALAYI

Other name:

• Aedes

• Anopheles

• Mansonia

BRUGIA MALAYI

Vectors Nocturnal:

Coquillettidia

BRUGIA MALAYI

Vectors Subperiodic:

BRUGIA MALAYI

Nocturnal periodicity; also has a Nonperiodic form; sheath stains bright pink with Giemsa

Lymphangitis and filarial abscesses

occur with a greater degree of frequency than in W.bancrofti infections

BRUGIA MALAYI

Clinical disease progresses faster than in W.bancrofti

BRUGUA TIMORI

shows Nocturnal periodicity

BRUGUA TIMORI

Microfilaria is morphologically similar to B.malayi microfilariae, except that on average they are longer and the sheath does not stain well with Giemsa

BRUGUA TIMORI

DIAGNOSIS: similar methods with W.bancrofti

Anopheles spp. mosquitoes

BRUGUA TIMORI

Vector:

W. BANCROFTI VS B. MALAYI

Both endemic in the Philippines

Female Aedes mosquito

W. BANCROFTI VS B. MALAYI

The main vector of the two is:

Graceful/ Smooth

Wuchereria bancrofti

Movement:

Not overlapping

Wuchereria bancrofti

Nuclei:

W. BANCROFTI VS B. MALAYI

Sheath: Sheathed

No terminal nuclei

Wuchereria bancrofti

Terminal nuclei:

Kinky/Stiff appearance

Brugia malayi

Movement:

Overlapping

Brugia malayi

Nuclei:

With 2 terminal nuclei; bulge around 2 nuclei

Brugia malayi

Terminal nuclei:

WUCHERERIA BANCROFTI

Elephantiasis above the knee:

BRUGIA MALAYI

Elephantiasis below the knee:

LOA LOA

Exhibits Diurnal periodicity; sheath does not stain with Giemsa

African Eye worm

LOA LOA

Other name:

Chrysops spp. (Fruit Fly/ Mango Fly/ Tabanid Fly/ Deer Fly)

LOA LOA

Vectors:

Subcutaneous tissue

LOA LOA

LIFECYCLE: Adults reside in the

Blood

LOA LOA

LIFECYCLE: Larva (microfilaria) can be detected in the

• Chrysops bite

• Calabar/Fugitive swellings

• Cardiomyopathy, encephalopathy, nephropathy and pleural effusions

LOA LOA

SYMPTOMS AND PATHOLOGY:

Identification of adult worm from the eye, in tissue or in peripheral blood

LOA LOA

Definitive Diagnosis:

• Surgical removal of the worms

• Diethylcarbamazine, Albendazole, Ivermectin

LOA LOA

TREATMENT:

ONCHOCERCA VOLVULUS

Convoluted/Binding Filaria

Onchocerciasis or River Blindness

ONCHOCERCA VOLVULUS

Disease/Condition:

River Blindness Worm/Blinding Worm

ONCHOCERCA VOLVULUS

Other name:

Simulium spp (Black Fly/Buffalo Gnat)

ONCHOCERCA VOLVULUS

Vector:

• Onchocercomas

• Skin changes

• Sowda

• Ocular involvement

ONCHOCERCA VOLVULUS

SYMPTOMS AND PATHOLOGY:

Onchocercomas

firm, round and nontender subcutaneous nodules that contain the adult worms

ONCHOCERCA VOLVULUS

lizard/leopard skin (localized areas of spotty depigmentation surrounded hyperpigmentation zones)

ONCHOCERCA VOLVULUS

results in a condition referred to as “hanging groin” that may develop into a hernia

Sowda

Chronic, hyperactive form; characterized by a severe popular dermatitis, usually localized to one limn, typically a leg with darkening of the skin

• Skin snips/skin biopsies

• Slit-lamp of the eye

• Mazzotti test

• Serologic tests

• PCR methods

ONCHOCERCA VOLVULUS

LABORATORY DIAGNOSIS:

Mazzotti test

used when results with the skin snips are negative

Serologic tests

use of recombinant antigens

PCR methods

more sensitive than routine microscopic methods

• Surgical removal of the worms

• Ivermectin (drug of choice)

ONCHOCERCA VOLVULUS

TREATMENT:

MANSONELLA SPP.

• Generally not associated with serious infections

• (less severe infections)

Culicodes spp/Midge

MANSONELLA SPP.

Vector:

MANSONELLA OZZARDI

Can be found in the thoracic and peritoneal cavities and possibly the lymphatics but there is generally no inflammation

Ozzard’s filariasis

MANSONELLA OZZARDI

Disease /Condition:

can also use Simulium spp

MANSONELLA OZZARDI

Vector:

New World Filaria

MANSONELLA OZZARDI

Common Name:

MANSONELLA PERSTANS

Adults reside in the pericardial, pleural and peritoneal cavities

Pericardial, Pleural, & Peritoneal

MANSONELLA PERSTANS

Habitat Adults: