Filariasis

Question 1

life cycle of dracunculus medinensis

Answer 1

1. human drinks unfiltered water containing copepods with L3 larvae
2. larvae are released the copepods die. Larvae penetrate the host’s stomach and intestinal wall. They mature and reproduce
3. fertilised female worm migrates to surface of skin, causes a blister and discharges larvae
4. L1 larvae released into water from the emerging female worm
5. L1 larvae consumed by a copepod
6. larvae undergoes two bolts in the copepod and becomes a L3 larvae

Question 2

WHO target on guinea worm

Answer 2

eradication campaign has been a big success thanks to distribution of pipe to block ingestions of worms in drinking water

Question 3

WHO target on lymphatic filariasis

Answer 3

one billion at risk, mostly in tropical regions, and 40 million severely incapacitated or disfigured. two separate drugs to prevent transmission

Question 4

WHO target on river blindness

Answer 4

caused by infection by the nematode worm. about 500,000 people thought to be blinded, mostly in sub-Saharan Africa

Question 5

WHO target on schistosomiasis

Answer 5

life-threatening urinary or liver damage or cancers. 76 million children need single dose treatment

Question 6

what type of cell is Filariasis?

Answer 6

phylum nematoda

belongs to superfamily filaroidea

Question 7

what is ovoviviparous?

Answer 7

producing eggs that are hatched within the body, so that the young are born alive but without placental attachment

Question 8

which are the developmental stages of filariasis?

Answer 8

egg –> L1 –> L2 –> L3 –> L4 –> adult

Question 9

when does the development arrests?

Answer 9

at L1 and L3

Question 10

how many species of filarial nematodes use humans as the definitive host?

Answer 10

9

Question 11

what is a definitive host?

Answer 11

the one in which the sexually reproducing adults develop

Question 12

how are filarial nematodes transmitted?

Answer 12

by blood-feeding insects

Question 13

what are vectors?

Answer 13

intermediate hosts

Question 14

groups of filarial nematodes according to the niche they occupy

Answer 14

1. lymphatic filariasis
2. subcutaneous filariasis
3. serous cavity filariasis

Question 15

what does lymphatic filariasis involve?

Answer 15

lymphatic system, including the lymph nodes - can cause elephantitis

Question 16

examples of species that cause lymphatic filariasis

Answer 16

Wucheria bancrofti, Brugia malayi, Brugia timori

Question 17

what does subcutaneous filariasis involve?

Answer 17

subcutaneous layer of the skin, fat layer

Question 18

examples of species that cause subcutaneous filariasis

Answer 18

Loa loa (African eye worm), Onchocerca volvulus (riverblindness), Dracunculus medinensis (Guinea worm), Mansonella streptocerca

Question 19

what does serous filariasis involve?

Answer 19

serous cavity if the abdomen

Question 20

examples of species that cause serous cavity filariasis

Answer 20

Mansonella perstans ad Mansonella ozzardi

Question 21

what is lymphatic filariasis’s vector?

Answer 21

culex mosquitos

Question 22

lymphatic filariasis infection cycle

Answer 22

1. mosquito takes a blood meal (L3 larvae enters skin)
2. adults in lymphatics
3. adults produce sheathed microfilariae that reach the blood stream
4. mosquito takes blood meal (ingests microfilariae)
5. microfilariae shed sheaths, penetrate mosquito’s midgut, and migrate to thoracic muscles
6. L1 larvae
7. L3 larvae
8. Migrate to head and mosquito’s proboscis

Question 23

which microfilaria are sheathed?

Answer 23

Wuchereria bancrofti, Brugia malayi and Brugia timori

Question 24

what is the sheath?

Answer 24

the eggshell

Question 25

what time of the day is there the maximum presence if microfilariae in the blood?

Answer 25

at night

Question 26

how is Wucheria and Brugia microfilariae cycles?

Answer 26

periodic

Question 27

what type of disease is filariasis?

Answer 27

a spectral disease

Question 28

what types of people ate there in endemic areas?

Answer 28

3 classes: 1. microfilaria positive 2. chronic pathology 3. endemic normal

Question 29

characteristics of a microfilaria positive person

Answer 29

usually asymptomatic, but the infection is active | --> due to defective T cell proliferative responses

Question 30

characteristics of a chronic pathology person

Answer 30

cleared infection - normal proliferative response - immunopathology

Question 31

characteristics of an endemic normal person

Answer 31

no or very low level infection - normal immune response

Question 32

what type of effects does filariasis cause?

Answer 32

trans-generational effects

Question 33

where are the endosymbiotic bacterium?

Answer 33

in insect-transmitted filarial worms

Question 34

how are most species of filarial worms?

Answer 34

harbour bacterial and endosymbionts

Question 35

what family do endosymbiotic bacterium belong to?

Answer 35

members of the Wolbachia family, related to rickettsia

Question 36

how can Wolbachia DNA be detected?

Answer 36

by chemotherapy

Question 37

what is Wolbachia appears to be essential for?

Answer 37

for worm fertility/viability/survival

Question 38

what happens to the worm if you kill the Wolbachia?

Answer 38

it sterilises the worm

Question 39

what is wolbachia involved in in riverblindness?

Answer 39

appears to have a role in pathogenesis particularly after death of microfilariae

Question 40

drugs for killing adult filarial worms?

Answer 40

1. Albendazole (anthelmintic) combined with ivermectin 2. a combination of diethylcarbamazine (DEC) and albendazole is also effective 3. tertacyclines against endosymbiotic bacterium - Wolbachia --> azithromycin for treatment of lymphatic filariasis

Question 41

what is the vector for river blindness (onchocerciasis)?

Answer 41

stimulium damnosum or Dipteran fly (insect vector)

Question 42

what does the stimulium damnosum requires for its larvae?

Answer 42

oxygenated water

Question 43

do mosquitos need oxgenate water for its larvae?

Answer 43

No

Question 44

the onchocerca vulvus (causative agent for river blindness) life cycle

Answer 44

1. blackfly takes blood meal (L3 lavae enter the wound) 2. subcutanenous tissues 3. adults in subcutaneous nodule 4. adults produce unsheathed microfilariae that typically ate found in skin ad in lymphatics of connective tissues, but also occasionally in peripheral blood, urine and sputum 5. blackfly takes a blood meal (ingests microfilariae) 6. microfilariae penetrate blackfly's midgut and migrate to thoracic muscles 7. L1 larvae 8. L3 larvae 9. migrate to head and blackfly's probscis

Question 45

what does river blindness cause in the head of infected people?

Answer 45

protuberances

Question 46

what are other skin manifestations of onchocerciasis?

Answer 46

1. sowda 2. leopard skin 3. elephant skin

Question 47

what is sowda?

Answer 47

a cutaneous condition, a localised type of onchocerciasis

Question 48

what is leopard skin?

Answer 48

a term referring to the spotted depigmentation of the skin that may occur with onchocerciasis

Question 49

what is elephant skin?

Answer 49

when the skin eventually loses elasticity in onchocerciasis

Question 50

what are the main objectives in the OCP (Onchocerciasis control programm(, now the APOC (African programme onchocerciasis control)?

Answer 50

1. vector control 2. screening and drugs: - diethylcarbamazine (DEC) and the Mazzotti reaction - ivermectin: diminish Mazzotti reaction - tetracyline: sterilises adult females

Question 51

what is the Mazzotti reaction?

Answer 51

Mazzotti reactions can be life-threatening, and are characterized by fever, urticaria, swollen and tender lymph nodes, tachycardia, hypotension, arthralgias, oedema, and abdominal pain that occur within seven days of treatment of microfilariasis.

Question 52

loa loa infection cycle

Answer 52

1. fly takes blood meal (L3 larvae enter the wound) 2. adult in subcutaneous tissue 3. adults produce sheathed microfilariae that are found in the spinal fluid, urine, sputum, peripheral blood and in the lungs 4. fly takes a blood meal (ingests microfilariae) 5. microfilarae shed sheaths, penetrate fly's midgut, and migrate to thoracic muscles 6. L1 larvae 7. L3 larvae 8. migrate to head and fly's sproboscis