Diseases & National Health Programme
Which of the following is the infective form of Ancylostoma duodenale?
|A||Rhabditiform larva after molting twice|
|B||Freshly hatched rhabditiform larva|
a. Hookworm infection is defined as any infection caused by Ancylostoma duodenale or Necator americanus.
b. Hookworm infection is widely prevalent in India. Necator americanus is predominant in South India, and Ancylostoma duodenale in North India.
c. Chandler's index is used irr epidemiological studies of the hookworm disease. Adult worms live in the small intestine, mainly jejunum where they attach themselves to the villi. Eggs are passed in the feces in thousands.
d. When deposited on warm, moist soil a larva rapidly develops in the egg and hatches after 1-2 days.
e. This rhabditiform larva moults twice in the soil and becomes a skin-penetrating 3rd stage infective larva within 5-10 days. Infection occurs when the larva enters the body through the skin, most commonly through the feet.
f. Once inside the body, they migrate via lymphatics and bloodstream to the lungs. They break into the alveoli, ascend the bronchi and trachea and are coughed up and swallowed to reach the small intestine where they mature.