Brian OL Duke, River Blindness Foundation, Lancaster, UK
Published online: April 2001
DOI: 10.1038/npg.els.0002247
Filarial diseases are caused by nematode worms that spend part of their life cycle in human hosts, and part in a blood-sucking insect vector. According to species, the adult worms live in the human lymphatic vessels, the subcutaneous tissue and deep connective tissues, or in serous cavities.
Keywords: filariasis; loiasis; onchocerciasis
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Figure 1. The life cycle of filarial worms. For the four genera Wuchereria, Brugia, Onchocerca and Loa, the figure shows the approximate range in size of the various stages in the life cycle (in the human host and in the vector), together with the approximate range in the duration of each stage.
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Figure 2. Elephantiasis of the right lower leg due to infection with Brugia malayi in an Asian patient.
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Figure 3. A female Simulium damnosum s.l. (the main black fly vector of Onchocerca volvulus in Africa), which has just taken a full blood-meal from a volunteer.
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Figure 4. Onchocerca volvulus nodule on the chest wall of an African man.
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Figure 5. ‘Sowda’ lesions of onchocerciasis in the skin of the left leg of an African woman.
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Figure 6. A female red fly (Chrysops silacea) from the Cameroon rainforest. This insect is one of the main vectors of Loa loa in Africa.
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Figure 7. Adult Loa loa worm crossing the eyeball of an African patient.
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Figure 8. A female midge (Culicoides grahamii) from a banana plantation in Cameroon, fully fed on blood from a volunteer. This insect is one of the main vectors of Mansonella streptocerca in Africa.
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| References | |
| Amaral F, Dreyer G, Figuerado-Silva J et al. (1994) Live adult worms detected by ultrasonography in human bancroftian filariasis. American Journal of Tropical Medicine and Hygiene 50: 753–757. | |
| Anderson J and Fuglsang H (1977) Ocular onchocerciasis. Tropical Diseases Bulletin 74: 257–272. | |
| Boussinesq M, Gardon J, Gardon-Wendel N et al. (1998) Three probable cases of Loa loa encephalopathy following ivermectin treatment for onchocerciasis. American Journal of Tropical Medicine and Hygiene 58(4): 461–469. | |
| Ottesen EA, Duke BOL, Karam M and Behbehani K (1997) Strategies and tools for the control/elimination of lymphatic filariasis. Bulletin of the World Health Organization 75(6): 491–503. | |
| Meyers WM, Connor DH, Harman LE et al. (1972) Human streptocerciasis. A clinico-pathologic study of 40 Africans (Zairians) including identification of the adult filaria. American Journal of Tropical Medicine and Hygiene 21: 1137–1147. | |
| Murdoch ME, Hay RJ, Mackenzie CD et al. (1993) A clinical classification and grading system of the cutaneous changes in onchocerciasis. British Journal of Dermatology 129: 260–269. | |
| Nutman TB, Kirk KD, Mulligan M et al. (1988) Diethylcarbamazine prophylaxis for human loiasis: results of a double-blind study. New England Journal of Medicine 319: 752–756. | |
| Taylor HR and Greene BM (1989) The status of ivermectin in the treatment of onchocerciasis. American Journal of Tropical Medicine and Hygiene 41: 460–466. | |
| Further Reading | |
| Boussinesq M and Gardon J (1998) Challenges for the future – loiasis. Annals of Tropical Medicine and Parasitology 92(supplement 1): S147–S151. | |
| Fain A (1978) Les problèmes actuels de la loase. Bulletin of the World Health Organization 56: 155–167. | |
| book Duke BOL (1996) "Filariasis". In: Weatherall DJ, Ledingham JGG and Warell DA (eds) Oxford Textbook of Medicine, 3rd edn, vol. 1, sec. 7.14.1, pp. 911–919. Oxford: Oxford University Press. | |
| Ottesen EA, Duke BOL, Karam M and Behbehani K (1997) Strategies and tools for the control/elimination of lymphatic filariasis. Bulletin of the World Health Organization 75(6): 491–503. | |
| book Sasa M (1976) Human Filariasis – A Global Survey of Epidemiology and Control, pp. 1–819. Baltimore, MD: University Park Press. | |
| book Southgate BA (1996) "Lymphatic filariasis". In: Weatherall DJ, Ledingham JGG and Warell DA (eds) Oxford Textbook of Medicine, 3rd edn, vol. 1 sec. 7.14.2, pp. 919–924. Oxford: Oxford University Press. | |
| book World Health Organization (1974) In: Buck AA (ed.) Onchocerciasis – Symptomatology, Pathology, Diagnosis, pp. 1–80. Geneva: World Health Organization | |
| report World Health Organization (1992) Lymphatic filariasis: the disease and its control. Fifth Report of the WHO Expert Committee on Filariasis, WHO Technical Report Series No. 821, pp. 18–71. Geneva: World Health Organization. | |
| report World Health Organization (1995) Onchocerciasis and its control. Report of a WHO Expert Committee on Onchocerciasis Control, WHO Technical Report Series 852, pp. 1–103. Geneva: World Health Organization. | |
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