Life cycles of nematode, ascarid, ancylostoma, Trichuris, Toxascaris leonina, Transtracheal migration
Nematode LC (10)
3. Vermiform Embryo
4. hatch to L1 (stage 1)
5. molt L2 (stage 2)
6. molt L3 (stage 3)
7. molt L4 (stage 4)
8. molt L5 (stage 5)
Ascarid LC (4)
1. Eggs/ L2 (infective stage) is
2. Larve penetrates the stomach and enters the hepatic portal circulation in the liver
3. the larva then goes to the lungs via the vena cava, right auricle, right atrium, tricuspid valve, right ventricle, pulmonary valve and pulmonary artery
4. larvae enter the alveoli, are coughed up into the trachea and mouth, are swallowed, molt once in the stomach and then go to the small intestines mature and reproduce.
1. Egg(passed in feces)
2. (hatch in 2-8days) L1
3. molt L2
4. molt L3(infective stage) swallowed
or penetrates skin, and matures to adult stage
5. molt L4
6. molt L5 à attaches to intestines.
Trichuris LC (6)
1. Eggs are passed in the feces
2. egg develops into 2 cells and then
into more cells
3. Cells form L1 larvae (infective)
4. Egg is then ingested by the host and
5. L1 develops in the small and large
intestines (molt to L5)
6. Adults migrate to the cecum and reproduce
Strongyloides LC (5)
1. Three forms exist – an asexual very pathogenic female (passes eggs that develop without being fertilized), and a sexual male and sexual female that are passed as a vermiform embryo. Sexual females and sexual males produce sexual males and sexual females only and the pathogenic female produces pathogenic females only, as far as we know.
2. After being passed, the larvae will go through two molts to the infective 3rd stage.
3. Infective 3rd stage larvae are consumed or penetrate the skin.
4. The 3rd stage larvae will migrate through the circulation to the lungs, where they are coughed up, swallowed, and make their way back to the intestines where they molt twice to the 4th and 5th stages.
5. The adult larvae reproduce and the eggs can be shed in the feces 7 to 20 days after infection.
HW LC (8)
1. dog 1 has adults(S5) and microfilaria(S1)
2. mosquito takes blood and picks up S1
3. S1 molts to S3 in mosquito (time depends on temp)
4. mosquito inserts S3&saliva into dog 2
5. S3 molts to S4 in subcutaneous tissue
6. S4 stays in SQ tissue for 100 days
7. S4 molts to S5(pre-adult) and moves to pulmonary artery
8. S5 stays in pulmonary artery for 80 days then molts to adult S5