Filariasis (Philariasis) By: Hani Joseph

1. Filariasis (Philariasis) By: Hani Joseph

2. Definition • Is a parasitic disease, that is caused by thread-like filarial nematodes (roundworms) . • And considered as an infectioustropical disease.

3. Types of Filariasis • There are 9 known filarial nematodes which use humans as their definitive host. • These are divided into 3 groups according to the niche within the body that they occupy: • Lymphatic filariasis , • Subcutaneous filariasis , • and Serous cavity filariasis .

4. Lymphatic filariasis • Is caused by the worms Wuchereria bancrofti, Brugia malayi, and Brugia timori. • These worms occupy the lymphatic system, including the lymph nodes, and in chronic cases these worms lead to the disease Elephantiasis .

7. Transmission The disease is transmitted by mosquitoes that bite infected humans and pick up the microfilariae that develop inside the mosquito, into the infective stage in a process that usually takes 7-21 days.

8. Prevalence

9. How common is lymphatic filariasis? • At least 120 million people in 73 countries worldwide are estimated to be infected with filariasis parasites. • Almost 25 million men have genital disease (most commonly hydrocele) and almost 15 million, mostly women, have lymphoedema or elephantiasis of the leg.

10. Approximately 66% of those at risk of infection live in the South-East Asia Region and 33% in the African Region. • The most widespread is Wuchereria bancrofti, which affects about 100 million people in Africa, India, Southeast Asia, the Pacific islands, South America, and the Caribbean. The Brugia malayi and Brugia timori parasites affect about 12 million people in Southeast Asia.

11. Wuchereria bancrofti

12. Worm lifecycle

13. Symptoms • The most spectacular symptom of lymphatic filariasis is Elephantiasis—edema with thickening of the skin and underlying tissues which was the first disease discovered to be transmitted by mosquito bites . • Elephantiasis affects mainly the lower extremities, while the ears, mucus membranes, and amputation stumps are affected less frequently. • Note: Elephantiasis results when the parasites lodge in the lymphatic system.

14. Diagnosis • Filariasis is usually diagnosed by identifying microfilariae on Giemsa stained thin and thick blood film smears, using the "gold standard" known as the finger prick test. • Polymerase chain reaction (PCR) and antigenic assays, which detect circulating filarial antigens, are also available for making the diagnosis.

15. Treatment • Diethylecarbamacine: 100mg three times a day for 3 weeks & for 5 days every six months. • Albendazole (a broad spectrum anthelmintic) combined with Ivermectin. • A combination of Diethylcarbamacine (DEC) and Albendazole is also effective . • Note : All of these treatments are microfilaricides, they have no effect on the adult worms.

16. Strategy to eliminate lymphatic filariasis • The strategy to Eliminate Lymphatic Filariasis has two components: • First, to stop the spread of infection (i.e. interrupt transmission), and • Secondly, to alleviate the suffering of affected individuals (i.e. morbidity control).

17. Conclusion To alleviate the suffering caused by the disease, it will be necessary to implement community education programmes to raise awareness in affected patients. This would promote the benefits of intensive local hygiene and the possible improvement, both in the damage that has already occurred, and in preventing the debilitating and painful, acute episodes of inflammation.