FURTHER OBSERVATIONS O N HYPERENDEMIC ONCHOCERCIASIS IN T H E UPPER TARABA RIVER VALLEY, NIGERIA
AKOGUN O. B.* & RENZ A.**
Keywords : Onchocerca volvulus- blinding onchocerciasis. Taraba river valley.
Nigeria.
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o l l o w i n g an earlier report o f s e v e r e o c u l a r o n c h o c e r c i a s i s in t h e m i d d l e T a r a b a r i v e r v a l l e y , N i g e r i a ( A k o g u n 1 9 9 2 ) a n d t h e n e e d t o identify all c o m m u n i t i e s w h i c h m a y benefit from ivermectin treatment, an e p i d e m i o logical survey o f the less easily a c c e s s i b l e c o m m u n i t i e s o f the u p p e r T a r a b a river valley w a s carried out.O f the 2 . 1 7 6 p e o p l e from 12 c o m m u n i t i e s that w e r e e x a m i n e d for the p r e s e n c e o f the microfilariae o f Onchocerca vol
vulus a n d t h e clinical s y m p t o m s o f o n c h o c e r c i a s i s , 6 1 . 8 % w e r e microfilaria] positive a n d the intensity o f infection w a s 7 8 . 9 m i c r o f i l a r i a e / s k i n - s n i p . Infection rates e x c e e d e d 6 0 % in n i n e c o m m u n i t i e s (with 1 0 0 % in o n e c o m m u n i t y a n d 9 8 . 5 % in a n o t h e r ) . T w o c o m m u n i t i e s h a d 4 5 . 4 % a n d 3 2 . 2 % w h i l e the r e m a i n i n g c o m m u n i t y h a d 9.1 %. As the rate a n d intensity o f infection i n c r e a s e s s o d o e s the preva
l e n c e o f l e o p a r d skin a n d n o d u l e carriage.
E y e l e s i o n s a n d b l i n d n e s s w e r e b r o a d l y d e f i n e d as a n y visible circular or l o c a l i s e d c o r n e a l ~snowflak.es' or o c c l u s i o n o f the pupil a n d inability to read the 6 / 6 0 VE ' c a r d at 3 m respectively. E y e l e s i o n s w e r e e s p e c i a l l y high ( 2 7 . 1 % ) a n d r e a c h e d 5 6 . 7 % in o n e c o m m u n i t y . In six c o m m u n i t i e s the p r o p o r t i o n o f the p o p u l a t i o n with e y e lesions e x c e e d e d 3 0 %. B l i n d n e s s as r e c o r d e d in all but o n e c o m m u n i t y a n d its p r e v a l e n c e r a n g e d b e t w e e n 3.2 % a n d 6 2 . 5 % with an overall a v e r a g e o f 19-7 %. E y e l e s i o n s w e r e rare b e f o r e the a g e o f 2 0 years but b l i n d n e s s i n c r e a s e d from 1 7 . 4 % in a g e 2 0 - 2 9 y e a r s to 5 4 . 6 % at a g e 5 0 y e a r s (N = 9 7 2 ) . T h e s e surveys indicate that the u p p e r T a r a b a valley is w o r s e t h a n the mid-valley area a n d that the T a r a b a h a s the worst blin
ding o n c h o c e r c i a s i s in Nigeria.
T h e transmission o f O. volvulus at t h r e e sites o f the T a r a b a valley is currently b e e n a s s e s s e d .
* Federal University o f T e c h n o l o g y , Department o f Biological Sciences . Yola. Nigeria
**Universität Hohenheim, Fachgebiet Parasitologic (Institut für Zoologie). 70599 Stuttgart, Germany
E P I D E M I O L O G Y O F F I L A R I A S I S
Parasite, 1994, 1, I S 13
Article available athttp://www.parasite-journal.orgorhttp://dx.doi.org/10.1051/parasite/199401s1013
