Filarial Worms

parts of the lymphatic system

lymph nodes

spleen

thymus

tonsils

bone marrow

what type of worm is the filarial worm

nematodes (round worm)

where do filarial worms reside in

lymphatic (immune system)

subcutaneous tissues

how are filarial worms transmitted

mosquitos

what are the mosquitos normally infected with

wolbachia spp

what do filarial worms cause

lymphatic filariasis

river blindeness

wuchereria bancrofti

lymphatic filariasis

life cycle of wuchereria bancrofti

1. mosquito takes blood meal and L3 larvae enter skin

2. adults in lymphatics

3. adults produce sheathed microfilariae that are in the blood (diagnostic)

4. if not picked up within a month by mosquito die

5. mosquito takes blood meal ingests microfilariae

6. microfilariae shed sheaths and go in midgut

7. microfilariae go to midgut then to migrate to thoracic muscles

8. L1 in thoarastic

9. L2 molt/ L3 from thorax to provoscus

10. L3 from blood skin

anopheles

culex

aedes

where are anophoeles found

rural

where are culex found

urban and semi urban

where are aedes found

pacific islands

what are 50% of all lymphatic filariasis infection

culex quinquefasciatus

what are culex quinquefasciatus

highly anthropophilic

rests and feeeds indoors and outdoors

stagnant and poluted water as breeding

in high density and urban areas

inflammatory Phase

acute filarial lymphangitis

• due to death of adult worms

mild symptoms of inflammatory phase

malaise and chills

painful swollen local lymph nodes

fever

complications of inflammatory phase

adenolymphangitis (inflammation of lymph nodes and vessels)

Asymptomatic phase

high microfilaremia

endemic normals

no microfilariae circulating, no transmission exposed to pathogen continuously

what do casual visitors sufer from

acute lymphatic inflammation and no microfilaremia

child born with microfilaremic mother

likely to have no symptom but are microfilaremic in blood

microfilaments in blood

different stages of lymphatic vessel

1. normal

2. slight impairment of lymphatic drainage in acute infection

   • filarial parasite

3. impaired lymphatic drainage and vessel remodeling during chronic infection/ elephantiasis

   • cause damage of valves

   • wolbachia

   • filarial parasite

pathogenesis

most infections acquired in child hood but then symptoms occur in adults

Multiple stages of filarial worms

asymptomatic

inflammatory

obstructive

clinical manifestations of filarial worms

lympho-edema of the limbs

genital disease

acute attacks

stages of pathogenesis of elephantiasis

1. swelling is soft, pits on pressure

2. protein in fluid hardens- no pit on pressure

3. cant fight infection and prone to bacterial and fungal

4. accumulated fluid also causes tissue to expand and bulge. elephantiasis

definitive host of filarial worms

humans

intermediate host of filarial worms

mosquitos- aedes, anopheles, culex

reservoir host

none

mode of transmission of filarial worms

mosquito bite

blood transfussion —> microfilaments in blood

risk factors of getting filarial worms

living in urban or semi-urban areas, outdoor activities

Microfilariae periodicity

there are more microfilarie in blood at different times of day. higher during dawn

hawking’s hypothesis

parasites modify behavior to increase transmission

increase amount of microfilarie when vector’s eating habits

change in oxygen tension in lungs worms could tell night from day

uterus of worms

L3

migrate to lymph system and are there 9-10 days before molt

L4

in lymph system molt to adult

adult filarial worms

lymphatic vessels

microfilariae

lymph and blood

Acute adenolymphangitis (ADL)

lymphatic vessel damage

bacterial infections

secondary infections cause acute attacks

• local pain

• swelling

  • fever and chills

obstructive phase

repeated ADL episode

damage to lymphatic vessels

usually lower limbs

• arms, breast, genitalia

elephantiasis

who is more prone to the obstructive phase

women

Hydrocele

due to accumulation of fluid in the cavity of tunica vaginalis

chyluria

milky urin- excess fat in urine

blocked lymph leaks into kidney or bladder

malnutrition and viatmin deficiency

stigmatization

affects poor

social edclusion

discrimination

misconceptions

sad and hopeless, suicidal

treatment of filarial worms

Mass drug administration

• interrupts transmission

• given to population at risk

• 5 years

treatment via morbidity

Morbibity management and disability prevention

• treats ADL

• management of lymphoedema

  • self care and exercise

global programme to eliminate lymphatic filariasis

1. chemo

2. control morbidity

3. vector control

what does chemo do for filarial worms

interrupt transmission

what does control morbidity do for filarial worms

treat ADL

surgery for hyderocele

educate on how to manage

how to control vector

insecticide-treated nets

Mass drug administration give what for filarial worms

diethylcarbamazine

ivermectin

what is given to kill microfilariae

ivermectin

who eliminated lymphatic filariasis

china and korea

1.

wucereria adult female

3.

anal musculature

uterus

vulva

ovary

intestine

8

gonopore

9.

nerve ring

10

oesophagus

pharynx

mouth

16.

wuchereria microfilaria

17.

somatic cell

18

epidermis

renette cells

20

cuticular body sheath

21.

oral style

nerve ring

bladder

24

nephridiopore

anus

4 large cells

testes

14

copulatory spicules

15

papillae

27

wucheria male