Filariasis

Question 1

What are filarial nematodes?

Answer 1

Thread like worms which live in the blood.

Question 2

What are the three species that cause lymphatic filariasis and where are they found geographically?

Answer 2

Wuchereria bancrofti (tropics), Brugia malayi (south east asia), Brugia timori (Indonesia)

Question 3

What are the vectors of lymphatic filarial worms?

Answer 3

Mosquitoes

Question 4

Where is the location of adult worms in LF?

Answer 4

lymph

Question 5

Where is the location of larvae in LF?

Answer 5

blood

Question 6

How do you distinguish between W.bancrofti and B.malayi?

Answer 6

Both sheathed, bancrofti nuclei don’t extend to tip of tail, B.malayi have a gap and then 2 terminal nuclei.

Question 7

Describe life cycle of B.malayi and W.bancrofti

Answer 7

1. Mosquito takes a blood meal, L3 larvae enter skin of human.
2. Larvae migrate to lymph nodes and develop into adult worms.
3. Adult worms produce sheathed microfilariae that are released into bloodstream.
4. Mosquito takes a blood meal and ingests MF.
5. MF shed sheath, penetrate midgut and migrate to thoracic muscles.
6. Migration of larvae to proboscis.

Question 8

What are the symptoms of LF?

Answer 8

elephantiasis, hydrocoele, lymphangitis, secondary infections

Question 9

LF methods of control?

Answer 9

mosquito control, large scale treatment of a population with albendazole and either ivm or dec to clear mf in blood

Question 10

LF treatment?

Answer 10

surgery for hydrocoele, albendazole + ivm or dec, doxycycline for wolbachia therapy

Question 11

When should a blood smear for diagnosis of LF be taken?

Answer 11

9pm-2am because of nocturnal periodicity- MF less active during the day as the mosquitoes bite at night

Question 12

What methods of LF diagnosis are there?

Answer 12

Giemsa stained thick blood smear
CFA antigen test (Bancrofti)
Brugia rapid dipstick
Ultrasound detection of adult worms

Question 13

What is hydrocoele

Answer 13

swelling of scrotum

Question 14

In filarial worms what does wolbachia depletion do?

Answer 14

1. Blocks embryogenesis- so no release of MF
2. Blocks transmission as parasites unable to develop in mosquito without it-no mf
3. adults die 1-2 years later

Question 15

What is the current AWOL goal for the future?

Answer 15

find a new anti-wolbachia drug with…

• less than 7 days regimen
• utility in children and women of child bearing age
• alternative drug against resistant parasites
• safe drug for Loa loa co-endemic areas

Question 16

What is the common name for Loiasis?

Answer 16

African Eye Worm

Question 17

What is the vector of Loa loa?

Answer 17

Chrysops ( horsefly/ deerfly)

Question 18

Where is Loa loa found?

Answer 18

Central and West Africa- affects forest dwellers

Question 19

How can you diagnose Loa loa?

Answer 19

1. adult worm visible migrating across front of eye

2. sheathed MF visible in blood film between 10am-2pm.

Question 20

What are the symptoms of loa loa?

Answer 20

Calabar swellings, itching, eye worm, eosinophilia

Question 21

Describe the life cycle of Loa loa

Answer 21

1. Day biting of fly, injects L3 into host
2. Migrate to subcutaneous tissue and mature into adults
3. Adult males and females mate and produce sheathed MF that migrate to skin, blood, urine, lungs, CNS.
4. Adult worms migrate through skin and eyes
5. MF taken up by fly bite
6. MF mature through several larval stages in fly and migrate to proboscis

Question 22

Treatment of Loa loa

Answer 22

Surgical removal of worms under skin and across eye

Question 23

Prevention of Loa loa

Answer 23

prevent bites, DEC prophylaxis (kills mf and adults), vector control

Question 24

What parasite causes river blindness and what is the vector?

Answer 24

Onchocerca volvulus, blackfly (Similum genus)

Question 25

Describe the life cycle of Onchocerca volvulus

Answer 25

1. Blackfly takes blood meal and L3 enter bite wound. 2. migrate to subcutaneous tissue 3. form nodules as they mature into adult worms 4. adult males and females mate within nodules 5. females release unsheathed MF which migrate to skin 6. blackfly takes a blood meal and ingests MF 7. MF mature through larval stages and migrate to proboscis

Question 26

Symptoms of river blindness

Answer 26

1. itchy skin rashes, skin nodules, vision changes ( due to immune response to dying MF) 2. blindness(immune response to dying mf in eye) 3. lizard skin atrophy 'aging' 4. leopard skin

Question 27

Diagnosis of river blindness

Answer 27

skin snip, examine eye, antibody test, pcr

Question 28

Treatment of river blindness

Answer 28

ivermectin, doxycycline, NO DEC

Question 29

prevention of river blindness

Answer 29

mass treatment at risk populations with ivermectin every 6-12 months vector control protect against bites

Question 30

What are the advantages of other diagnostic methods of LF over microscopy?

Answer 30

Can be taken any time of day, quick, whole blood fingerprick, more sensitive than mf

Question 31

what does MMDP stand for and what does it involve?

Answer 31

Morbidity Management Disability Prevention | Exercises, elevation, cleaning leg

Question 32

When do deerflies bite?

Answer 32

During the day

Question 33

What is Mansonellosis?

Answer 33

Skin filariasis caused by species of Mansonella species (M. ozzardi, M. perstans, M. streptocerca. Vector is midgies.

Question 34

What are calabar swellings?

Answer 34

Local skin swellings with oedema produced as worms migrate through skin.

Question 35

What parasite and vector causes Guinea worm?

Answer 35

Dracunculus medinensis, water flea

Question 36

Describe life cycle of guinea worm

Answer 36

1. Cyclops 'water flea' eats L1 and matures. 2. Ingestion of water containing infective L3 (either by human or fish/frogs) 3. Larvae penetrate gut wall of host when flea dies 4. Fertilized adult female migrates to skin surface and causes ulceration. 5. Release of L1 on contact with water

Question 37

Treatment of guinea worm

Answer 37

1. wind worm out around a matchstick over several days, but it can burst, releasing bacteria and causing cellulitis 2. tiabendazole decreases inflammation 3. prophylactic antibiotics

Question 38

Diagnosis of guinea worm

Answer 38

skin ulceration and emerging worm

Question 39

Prevention of guinea worm

Answer 39

1. safe drinking water 2. encourage infected people to avoid water during worm emergence 3. avoid bathing in a source of drinking water- disease mapping 4. health education

Question 40

Define control

Answer 40

The reduction of disease incidence, prevalence, morbidity or mortality; continued intervention measures are required to maintain the reduction

Question 41

Define elimination of disease

Answer 41

Reduction to zero of the incidence of a specified disease; continued intervention measures are required.

Question 42

Define elimination of infection.

Answer 42

Reduction to zero of the incidence of infection; continued measures to prevent re-establishment of transmission are require

Question 43

Define eradication

Answer 43

Permanent reduction to zero of the worldwide incidence of infection; intervention measures are no longer needed.

Question 44

What are main methods of prevention of filariasis?

Answer 44

MDA and vector control

Question 45

what are anti-wolbachia mode of action beneftis

Answer 45

- curative- slow kill avoids side effects - safe in loa loa co-infection - permanently sterilises adult worms- no recrudescence - blocks transmission - improves clinical disease

Question 46

why does the parasite need wolbachia?

Answer 46

- needed in many metabolic pathways such as tca cycle, purine and pyrimidine biosynthesis, supports growth and development of filarial nematodes at times of greatest metabolic demand - most at L4 stage - found in hypodermal cord cells and near reproductive organs in females