Question

The route through which developmental stages of Ascaris serially pass in man is
A. Outside \[ \to \] Intestine \[ \to \] Liver \[ \to \] Heart \[ \to \] Lung \[ \to \] Intestine \[ \to \] Outside
B. Outside \[ \to \] Esophagus \[ \to \] Stomach \[ \to \] Heart \[ \to \] Lung \[ \to \] Liver \[ \to \] Intestine \[ \to \] Outside
C. Esophagus \[ \to \] Mouth \[ \to \] Intestine \[ \to \] Liver \[ \to \] Lung \[ \to \] Heart \[ \to \] Trachea
D. Outside \[ \to \] Trachea \[ \to \] Lung \[ \to \] Heart \[ \to \] Liver \[ \to \] Intestine \[ \to \] Outside

Answer 1

Hint: Ascaris are parasitic worms also known as small intestinal roundworms and belong to the genus of parasitic nematodes. The disease caused due to the infection of these parasitic worms is known as Ascariasis.

Complete answer :
The infection by the parasite starts when the larval worms from the eggs laid in the soil enters into the human body. Within the human body, the first target of the parasite is the duodenal part of the small intestine. From the duodenum, the larvae enters into the circulating bloodstream. Through the blood, it enters into the liver by means of portal circulation. From the liver it reaches the heart, and subsequently the lungs by means of the circulatory system. The larvae start moulting within the lungs. And later it is again transported into the small intestine where the development into adult worms takes place. These worms are taken out of the human body through the digestive system and expelled along with the feces.
Considering the other given options:
B. The option is not the right one since the developmental process of the larvae into the adult worms does not happen in the esophagus or stomach. And also the passage of the larvae is from liver to heart and the lungs and not from heart and lungs to liver.
C. The option is not the right one since the developmental process of the larvae into the adult worms does not happen in the esophagus, mouth or trachea.
D. The option is not the right one since the developmental process of the larvae into the adult worms do not happen in the trachea. And also the passage of the larvae is from liver to heart and the lungs and not from heart and lungs to liver.

Hence the most appropriate answer is option A.

Note:
Ascariasis can cause major health problems in human beings. The most serious effect of the infection is the compromised nutritional status of the human host. It can also cause obstruction in the intestine and can also affect cognition. This disease is most commonly observed in children.