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Question
................... in the life cycle of Wuchereria bancrofti causes infection in humans
................... in the life cycle of Wuchereria bancrofti causes infection in humans
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Solution
The correct option is D 3rd stage larva
Once male and female nematodes mate the female viviparously produces microfilariae (first stage larvae or L1) which then move through the circulatory system and collect in arterioles of the lung during the day and emerge at night (if nocturnally periodic) when night biting mosquitoes are most active. Once, the microfilariae have entered an appropriate mosquito host through its blood meal they penetrate the insect's gut wall and move to the thoracic muscles where they mature (through two life stages) into third-stage infective larvae. Following infection with third stage larvae there is usually a period of vigorous immune response to the invading larvae. If the larvae are not cleared from the body during this period then the various pathologies associated with filarial infection can develop. Most of these conditions do not appear to arise from the effects of the nematodes themselves but from immune reactions to their presence. The most pronounced of these is the damage to the lymphatic vessels which is mediated by the immune system's response to the adult worms living in them. These immune responses (Lymphangitis) are characterized by inflammation of the affected area (which are usually extremities) and fever.
Once male and female nematodes mate the female viviparously produces microfilariae (first stage larvae or L1) which then move through the circulatory system and collect in arterioles of the lung during the day and emerge at night (if nocturnally periodic) when night biting mosquitoes are most active. Once, the microfilariae have entered an appropriate mosquito host through its blood meal they penetrate the insect's gut wall and move to the thoracic muscles where they mature (through two life stages) into third-stage infective larvae. Following infection with third stage larvae there is usually a period of vigorous immune response to the invading larvae. If the larvae are not cleared from the body during this period then the various pathologies associated with filarial infection can develop. Most of these conditions do not appear to arise from the effects of the nematodes themselves but from immune reactions to their presence. The most pronounced of these is the damage to the lymphatic vessels which is mediated by the immune system's response to the adult worms living in them. These immune responses (Lymphangitis) are characterized by inflammation of the affected area (which are usually extremities) and fever.
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