Question

Tomas is going to Africa and he is worried about filarial worms of Africa. What are they and how can they be prevented?

Answer 1

Filarial worms are transmitted to human through mosquito bite and causes the infection lymphatic filariasis called as elephantiasis.

There are three types of filarial worms: Wuchereria bancrofti - responsible for 90% of the cases ,Brugia malayi ,Brugia timori

Causes and transmission: Mosquitoes are infected with microfilariae by ingesting blood when biting an infected host. Microfilariae mature into infective larvae within the mosquito. When infected mosquitoes bite people, mature parasite larvae can enter the body and then migrate to the lymphatic vessels where they develop into adult worms, thus continuing a cycle of transmission.

Lymphatic filariasis is transmitted by different types of mosquitoes for example - Culex mosquito, Anopheles and Aedes.

Symptoms: asymptomatic- no external signs of infection and cause damage to the lymphatic system and the kidneys, and alter the body's immune system.

Chronic - lymphoedema (tissue swelling) or elephantiasis (skin/tissue thickening) of limbs and hydrocele (scrotal swelling). Involvement of breasts and genital organs is common.

Acute - local inflammation involving skin, lymph nodes and lymphatic vessels often accompany chronic lymphoedema or elephantiasis

Prevention: WHO recommends preventive chemotherapy strategy as a mass drug administration for elimination of lymphatic filariasis. It includes ivermectin (200 mcg/kg) together with diethylcarbamazine citrate (DEC) (6 mg/kg) and albendazole (400 mg) and Salt fortified with DEC.

Vector control strategy to control carrier of disease and treatment with antifilarial medicine and use of insecticide treated mosquito nets.