WORLD HEALTH ORGANIZATION
ORGANISATION MONDIALE DE LA SANTÉ
MEETING OF DIRECTORS OF WHO COLLABORATING CENTRES FOR VIRUS REFERENCE AND RESEARCH
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IN.
Geneva, 2 - 6 November 1 9 8 1 D r a f t agenda item 7 . 1
ARBOVIRUSES IN AFRICA by
M. Kalunda, V i r u s Research I n s t i t u t e , Entebbe, Uganda
I w i l l d i s c u s s arboviruses i n A f r i c a i n three c a t e g o r i e s , namely, t h o s e w h i c h a r e of i n t e r n a t i o n a l s i g n i f i c a n c e , those which are associated with f e v e r s o f undetermined o r i g i n and those which might p a r t i c i p a t e i n the e t i o l o g y of B u r k i t t ' s lymphoma.
A f r i c a i s the home of a l a r g e number of arboviruses w h i c h pose a g r e a t danger t o t h e world i n general and to A f r i c a i n p a r t i c u l a r . These v i r u s e s i n c l u d e y e l l o w f e v e r . L a s s a , Marburg, E b o l a , R i f t V a l l e y f e v e r and to a l e s s e r extent Congo-Crimean haemorrhagic f e v e r . These diseases have occurred mainly i n t r o p i c a l A f r i c a n c o u n t r i e s w i t h a l a r g e number of mammalian fauna and arthropods.
Yellow f e v e r
Outbreaks of y e l l o w f e v e r v i r u s i n f e c t i o n s have occurred i n West A f r i c a since 1977 and i n Ghana alone since 1 9 6 9 . 1 8 , 1 9 A large epidemic occurred a l s o i n Senegal i n 1965 with s e v e r a l
thousand cases and s e v e r a l hundred d e a t h s . ^ In Eastern A f r i c a the recent epidemics of y e l l o w f e v e r occurred i n the Sudan and western E t h i o p i a i n 1959^ and again i n south-west E t h i o p i a i n 1 9 6 0 - 1 9 6 2 producing enormous numbers of cases and between 15 000 and 30 000 d e a t h s . 1 0 , 1 1 These epidemics show that yellow f e v e r s t i l l e x i s t s i n most t r o p i c a l A f r i c a n c o u n t r i e s and t h e r e f o r e demand a continued s u r v e i l l a n c e .
The Table below i n d i c a t e s the o f f i c i a l n o t i f i c a t i o n s of t h i s disease i n A f r i c a since 1 9 7 7 . I t shows an increase i n both the number of cases and deaths, as w e l l as the spread to three other c o u n t r i e s between 1 9 7 7 and 1 9 7 9 . However, these o f f i c i a l n o t i f i c a t i o n s seem to underestimate the true f i g u r e s . For instance 3 0 cases, a l l of them f a t a l , were n o t i f i e d i n the Gambia i n 1 9 7 8 , but r e t r o s p e c t i v e c l i n i c a l survey revealed 271 suspected cases and 63 deaths. The r e t r o s p e c t i v e s e r o l o g i c a l survey increased these f i g u r e s to 5000-8000 cases and 1 0 0 0 - 1 7 0 0 d e a t h s . 1 8 > 1 9 xhe d i f f e r e n c e i n these f i g u r e s i s accounted f o r by d i f f i c u l t i e s i n i d e n t i f y i n g a t y p i c a l forms of y e l l o w f e v e r by c l i n i c a l examination without laboratory t e s t s . A l s o , some people, e s p e c i a l l y those l i v i n g i n r u r a l a r e a s , do not always seek medical treatment or r e p o r t a l l i l l n e s s e s and deaths. Hence, the e f f e c t of yellow f e v e r , l i k e that of other diseases discussed i n t h i s r e p o r t , i s by f a r greater than that determined from o f f i c i a l n o t i f i c a t i o n s .
L a s s a , Marburg and Ebola
These three diseases are some of the most important v i r a l diseases i n A f r i c a because o f the severe epidemics they have produced and the p o t e n t i a l threat of s i m i l a r epidemics
appearing outside A f r i c a .
Lassa v i r u s , an a r e n a v i r u s , caused an epidemic i n N i g e r i a i n 1969.'^ S i n c e t h e n , s e r o - e p i d e m i o l o g i c a l surveys have e s t a b l i s h e d that t h i s v i r u s i s a c t i v e i n a l l West A f r i c a n
c o u n t r i e s between Senegal and Z a i r e . In S i e r r a Leone alone t h i s disease accounts f o r 107» o f a l l f e b r i l e i l l n e s s e s and f o r 1.7% of the general death r a t e . ^ Recent s e r o l o g i c a l surveys
The issue of this document does not constitute Ce document ne constitue pas une publication, formal publication. It should not be reviewed. II ne doit faire l'objet d'aucun compte rendu ou abstracted or quoted without the agreement of résumé ni d'aucune citation sans l'autorisation de the World Health Organization. Authors alone l'Organisation Mondiale de la Santé. Les opinions are responsible for views expressed in signed exprimées dans les articles signés n'engagent articles. que leurs auteurs.
have e s t a b l i s h e d L a s s a v i r u s a n t i b o d i e s i n 4.81 o f 433 human samples f r o m L i b e r i a . More r e c e n t l y , 27.37, o f 44 s p e c i m e n s f r o m Sudanese m i l i t a r y p e r s o n n e l were f o u n d t o h a v e I F A a n t i b o d i e s t o p o l y v a l e n t US-MBG-EBO a n t i g e n s . I n S i e r r a Leone and G u i n e a , L a s s a f e v e r w a s f o u n d a s a d i s e a s e o f f o r e s t and savanna a r e a s . However, no e v i d e n c e o f t h i s d i s e a s e was f o u n d i n man i n the C e n t r a l A f r i c a n R e p u b l i c o r n o r t h e r n Z a i r e .6 Mastomys n a t a l e n s i s h a s been i d e n t i f i e d a s the r o d e n t r e s e r v o i r h o s t o f L a s s a v i r u s . I t s u f f e r s no i l l e f f e c t a n d d e v e l o p s no immune r e s p o n s e . ^
M a r b u r g v i r u s was f i r s t r e p o r t e d i n 1967 i n West Germany f r o m an o u t b r e a k o f a f a t a l h a e m o r r h a g i c d i s e a s e among l a b o r a t o r y w o r k e r s who h a d c o n t a c t w i t h t i s s u e s o f t h e A f r i c a n g r e e n monkey ( C e r c o p i t h e c u s a e t h i o p s ) f r o m Uganda. R e t r o s p e c t i v e f i e l d and l a b o r a t o r y s t u d i e s c o n d u c t e d i n Uganda f a i l e d t o show any c l i n i c a l e v i d e n c e o f a s i m i l a r d i s e a s e i n monkeys or.humans. However, HI a n t i b o d i e s were d e m o n s t r a t e d i n monkeys, i n d i c a t i n g t h a t M a r b u r g o r a c l o s e l y r e l a t e d v i r u s was a c t i v e i n Ugandan monkeys, some o f w h i c h were s e n t t o West Germany.'' S u b s e q u e n t l y , M a r b u r g v i r u s r e a p p e a r e d i n S o u t h A f r i c a i n 1975 a n d i n K e n y a
i n 1980.6 S e r o l o g i c a l s u r v e y s i n t h e human p o p u l a t i o n h a v e d e m o n s t r a t e d s p e c i f i c a n t i b o d i e s i n 1.4X o f 499 samples f r o m t h e C e n t r a l A f r i c a n R e p u b l i c and i n 27o o f 433 samples f r o m
L i b e r i a . More r e c e n t l y , 4.67. o f 237 human serum s a m p l e s f r o m Kenya h a d a n t i b o d i e s t o t h i s v i r u s . 6
E b o l a v i r u s c a u s e d two e p i d e m i c s o f h a e m o r r h a g i c d i s e a s e t n Z a i r e and t h e Sudan i n 1976 w i t h a t o t a l o f 537 n o t i f i e d c a s e s and 362 d e a t h s .^ ^ > , 17 xhe d i s e a s e r e a p p e a r e d i n t h e Sudan i n 1979 p r o d u c i n g 34 c o n f i r m e d c a s e s and 22 d e a t h s . ^ S e r o l o g i c a l s u r v e y s h a v e e s t a b - l i s h e d the p r e s e n c e o f E b o l a v i r u s i n 11% o f 433 p e r s o n s i n L i b e r i a and i n 67o o f S u d a n e s e . More r e c e n t l y , 8.47» o f 237 p e r s o n s i n Kenya were f o u n d t o be i n f e c t e d . However, e v i d e n c e o f t h i s v i r u s was n o t f o u n d i n Z a i r e a n monkeys, s q u i r r e l s , A f r i c a n p o r c u p i n e s , b a t s o r r o d e n t s .6
In summary, s e r o l o g i c a l s u r v e y s f o u n d E b o l a v i r u s i n r a i n f o r e s t s i n West and C e n t r a l A f r i c a and M a r b u r g v i r u s i n C e n t r a l , E a s t and S o u t h e r n A f r i c a . The p r e s e n c e o f a n t i b o d i e s t o
t h e s e t h r e e v i r u s e s i n many p e r s o n s who gave no h i s t o r y o f i l l n e s s o r c o n t a c t w i t h known c a s e s s u g g e s t s t h a t t h e s e v i r u s e s u s u a l l y c a u s e m i l d o r even a s y m p t o m a t i c i n f e c t i o n i n man. Once t h e s e v i r u s e s have been t r a n s m i t t e d t o man t h r o u g h c o n t a c t w i t h t h e i r r e s e r v o i r h o s t s , t h e y become c a p a b l e o f a d a p t i n g t o man-to-man t r a n s m i s s i o n , hence t h e g r e a t d a n g e r o f e p i s o d e s o f t h e s e d i s e a s e s i n non-endemic c o u n t r i e s
R i f t V a l l e y f e v e r
U n t i l r e c e n t l y . R i v e r V a l l e y f e v e r has n o t been an i m p o r t a n t human d i s e a s e b e c a u s e m o s t o u t b r e a k s a f f e c t e d d o m e s t i c a n i m a l s and a s m a l l number o f p e o p l e w o r k i n g c l o s e l y w i t h t h e s e a n i m a l s . ^ ' ^ Human d e a t h had n e v e r been d i r e c t l y a s c r i b e d t o R i f t V a l l e y f e v e r . H o w e v e r , t h e f i r s t s e v e r e human e p i d e m i c o f R i f t V a l l e y f e v e r o c c u r r e d i n South A f r i c a i n t h e e p i z o o t i c o f 1 9 5 0 - 1 9 5 1 , where R i f t V a l l e y f e v e r v i r u s was i s o l a t e d f r o m f i v e p e r s o n s . A s u b s e q u e n t e p i d e m i o l o g i c a l s u r v e y e s t i m a t e d 2 0 0 0 0 human c a s e s . ^ A g a i n , i n 1 9 7 5 , a n o t h e r e p i d e m i c o f R i f t V a l l e y f e v e r a p p e a r e d i n S o u t h A f r i c a i n w h i c h a t l e a s t f o u r p e r s o n s d i e d . ^ ^
The e p i d e m i c i n E g y p t i n 1977 was t h e l a r g e s t and the most f a t a l human e p i d e m i c o f R i f t V a l l e y f e v e r . The o f f i c i a l n o t i f i c a t i o n gave 18 0 0 0 human c a s e s a n d 598 d e a t h s . However, e s t i m a t e s o f c l i n i c a l c a s e s range between 2 0 0 0 0 and 2 0 0 0 0 0 . 8 The h i g h number o f human c a s e s and d e a t h s were a t t r i b u t e d t o t h e i n c r e a s e d v i r u l e n c e o f t h e v i r u s and p e r h a p s t h e h i g h s u s c e p t i b i l i t y o f the human p o p u l a t i o n i n E g y p t due t o endemic l i v e r d i s e a s e s , s u c h a s s c h i s t o s o m i a s i s. 8
A l t h o u g h t h e s o u r c e o f t h i s e p i d e m i c was n o t e s t a b l i s h e d , t h e o c c u r r e n c e o f a R i f t V a l l e y f e v e r e p i z o o t i c i n the Sudan i n 1976 s t r o n g l y s u g g e s t s t h a t t h e v i r u s was i n t r o d u c e d i n t o E g y p t f r o m t h e Sudan by i n f e c t e d c a m e l s . E g y p t i m p o r t s 50 0 0 0 - 1 0 0 0 0 0 Sudanese c a m e l s e v e r y y e a r .5 The a p p e a r a n c e o f R i f t V a l l e y f e v e r i n E g y p t i n 1977 and i t s r e a p p e a r a n c e i n 1978 and 1979 a s w e l l a s t h e p o t e n t i a l c o n t i n u e d s p r e a d i n E g y p t and o t h e r M e d i t e r r a n e a n c o u n t r i e s , r a i s e s c o n c e r n f o r p u b l i c h e a l t h i n t h i s r e g i o n and the w o r l d a t l a r g e .
A r b o v i r u s e s a s s o c i a t e d w i t h f e v e r s o f u n d e t e r m i n e d o r i g i n
The r o l e o f a r b o v i r u s e s i n f e v e r s o f u n d e t e r m i n e d o r i g i n i s n o t w e l l e s t a b l i s h e d i n
A f r i c a b e c a u s e some o f t h e e f f e c t s o f t h e s e v i r u s e s a r e a t t r i b u t e d t o m a l a r i a . Most f e b r i l e p a t i e n t s a r e t h e r e f o r e t r e a t e d f o r m a l a r i a b e f o r e t h e d i a g n o s i s i s c o n f i r m e d by l a b o r a t o r y t e s t s , w h i c h a r e n o t a l w a y s c o n d u c t e d due t o l a c k o f f a c i l i t i e s o r manpower. V i r a l i n f e c - t i o n s a r e t h e r e f o r e s u s p e c t e d o n l y a f t e r t h e f e v e r s f a i l t o r e s p o n d t o a n t i b i o t i c s and a n t i m a l a r i a l d r u g s . Specimens t a k e n f o r v i r u s i s o l a t i o n a t t h i s l a t e s t a g e u s u a l l y y i e l d n e g a t i v e r e s u l t s . H e n c e , v i r a l I n f e c t i o n s , p a r t i c u l a r l y t h o s e c a u s i n g s p o r a d i c c a s e s , a r e n o t n o r m a l l y c a t e r e d f o r i n p u b l i c h e a l t h .
The i m p o r t a n c e o f a r b o v i r u s e s i n p u b l i c h e a l t h c a n be shown by s t u d i e s c o n d u c t e d i n my I n s t i t u t e . A t t e m p t e d v i r u s i s o l a t i o n i s c o n d u c t e d on a c u t e b l o o d s a m p l e s f r o m f e b r i l e p a t i e n t s w i t h s u s p e c t e d v i r a l i n f e c t i o n s by s u c k l i n g m i c e i n o c u l a t i o n . I n t h e p a s t t h r e e y e a r s , 1 0 4 6 s p e c i m e n s were examined and t h e s e y i e l d e d 2 0 ( 1 . 9 7 o ) v i r a l i s o l a t e s . T h e s e i s o l a t e s h a v e b e e n i d e n t i f i e d a s f o l l o w s : 7 CHIK, 3 Congo, 2 Z i k a , 1 Dugbe and 1 WSL.
S i x r e m a i n i n g i s o l a t e s a r e i n t e r r e l a t e d and a r e a l s o d i s t a n t l y r e l a t e d t o Yogue v i r u s f r o m S e n e g a l . The i m p o r t a n c e o f a r b o v i r u s e s i n p u b l i c h e a l t h c a n a l s o be e m p h a s i z e d by t h e f i n d i n g g i v e n above t h a t L a s s a f e v e r a c c o u n t s f o r 1 0 7 o o f a l l f e b r i l e i l l n e s s e s i n S i e r r a L e o n e .
The r o l e o f a r b o v i r u s e s i n t h e p r o d u c t i o n o f B u r k i t t ' s lymphoma , .
B u r k i t t ' s lymphoma i s s u s p e c t e d t o be c a u s e d by an i n t e r a c t i o n b e t w e e n E p s t e i n - B a r r v i r u s and o t h e r a g e n t s . T h i s s u g g e s t i o n was made a f t e r f i n d i n g t h a t , a l t h o u g h E p s t e i n - B a r r v i r u s i s c o s m o p o l i t a n , B u r k i t t ' s lymphoma c a s e s a r e c o n f i n e d t o t r o p i c a l A f r i c a where m a l a r i a i s p r e v a l e n t . T h i s o b s e r v a t i o n prompted r e s e a r c h e r s t o c o n d u c t an e x p e r i m e n t i n T a n z a n i a t o f i n d o u t w h e t h e r c h e m o t h e r a p e u t i c s u p p r e s s i o n o f m a l a r i a r e s u l t s i n a r e d u c t i o n o f B u r k i t t ' s lymphoma c a s e s .2 The r e s u l t s a r e n o t y e t known. S i n c e c l i m a t i c c o n d i t i o n s f a v o u r a b l e t o v e c t o r s o f m a l a r i a a r e a l s o f a v o u r a b l e t o v e c t o r s o f a r b o v i r u s e s , t h e e t i o l o g y o f B u r k i t t ' s lymphoma c a n b e s t be e s t a b l i s h e d by c o n d u c t i n g s t u d i e s on t h e B u r k i t t ' s lymphoma t r i a d : E p s t e i n - B a r r v i r u s , m a l a r i a and a r b o v i r u s e s .
RECOMMENDATIONS Y e l l o w f e v e r
1 . V i r u s and s e r o e p i d e m i o l o g i c a l s t u d i e s s h o u l d be s t a r t e d o r c o n t i n u e d i n monkeys a n d r o d e n t s t o d e t e r m i n e t h e a c t i v i t i e s o f j u n g l e y e l l o w f e v e r i n endemic c o u n t r i e s so t h a t a p p r o p r i a t e p r e v e n t i v e m e a s u r e s c a n be t a k e n t o a v e r t e p i d e m i c s .
2 . The r o l e o f v a r i o u s s p e c i e s o f m o s q u i t o s , p a r t i c u l a r l y A e . a e g y p t i , A e . a f r i c a n u s and Ae. s i m p s o n i , f o u n d i n v a r i o u s endemic r e g i o n s s h o u l d be d e f i n e d i n r e l a t i o n s h i p t o e r u p t i o n s o f e p i d e m i c s by c o n d u c t i n g s t u d i e s s u c h as p o p u l a t i o n d e n s i t i e s , f e e d i n g h a b i t s and s u s c e p t i - b i l i t y t o y e l l o w f e v e r v i r u s .
3 . T h e r e i s a need t o d e t e r m i n e f a c t o r s w h i c h h a v e p r e v e n t e d t h e o c c u r r e n c e o f y e l l o w f e v e r e p i d e m i c s i n most E a s t e r n and C e n t r a l A f r i c a n c o u n t r i e s f o r many y e a r s d e s p i t e t h e f a c t t h a t y e l l o w f e v e r i s endemic i n t h e s e c o u n t r i e s and v a c c i n a t i o n h a s b e e n l i m i t e d t o i n f a n t s and o v e r s e a s t r a v e l l e r s .
4 . P r e c a u t i o n a r y measures a g a i n s t e p i s o d e s o f y e l l o w f e v e r s h o u l d i n c l u d e v a c c i n a t i o n c a m p a i g n s e v e r y 1 0 y e a r s i n a l l c o u n t r i e s v ^ e r e y e l l o w f e v e r i s e n d e m i c . F u r t h e r , p e r s o n s who a r e a t h i g h r i s k , n a m e l y , t h o s e w o r k i n g i n f o r e s t s as w e l l as m e d i c a l and l a b o r a t o r y p e r s o n n e l i n v o l v e d i n y e l l o w f e v e r s t u d i e s , s h o u l d r e c e i v e b o o s t e r d o s e s o f y e l l o w f e v e r v a c c i n e whenever n e c e s s a r y .
5. V i s i t o r s f r o m non-endemic c o u n t r i e s t o be v a c c i n a t e d a g a i n s t y e l l o w f e v e r r e g a r d l e s s o f the p e r i o d o f t h e i r s t a y i n y e l l o w f e v e r endemic c o u n t r i e s .
!
R i f t V a l l e y f e v e r
1 . S e r o e p i d e m i o l o g i c a l s u r v e y s t o b e c o n d u c t e d i n a l l A f r i c a n S t a t e s t o d e t e r m i n e t h e d i s t r i b u t i o n o f R i f t V a l l e y f e v e r i n man and l o w e r a n i m a l s .
2. S u r v e i l l a n c e o f R i f t V a l l e y f e v e r v i r u s c o n d u c t e d i n e n d e m i c c o u n t r i e s t o i n c l u d e t h e t r a c i n g o f t h e s o u r c e o f i n f e c t i o n a n d t h e s u r v e i l l a n c e o f i m p o r t e d a n i m a l s a n d a n i m a l p r o d u c t s o f a l l t y p e s .
3. The r o l e p l a y e d by i m p o r t e d and smuggled a n i m a l s and a n i m a l p r o d u c t s i s t o b e d e f i n e d i n r e l a t i o n s h i p t o the d i s s e m i n a t i o n o f R i f t V a l l e y f e v e r .
4. L a r g e q u a n t i t i e s o f R i f t V a l l e y f e v e r v a c c i n e o f r e c o g n i z e d q u a l i t y , s a f e t y and e f f i c a c y t o be p r e p a r e d and made a v a i l a b l e f o r emergency use i n man and d o m e s t i c a n i m a l s .
O t h e r a r b o v i r u s e s
1 . The i m p o r t a n c e o f a r b o v i r u s e s , p a r t i c u l a r l y t h o s e c a u s i n g v i r a l h a e m o r r h a g i c f e v e r ( V H F ) t o be e m p h a s i z e d by e n c o u r a g i n g s p e c i m e n c o l l e c t i o n f r o m a c u t e c a s e s o f s u s p e c t e d v i r a l
i n f e c t i o n s .
2. WHO t o c o l l a b o r a t e w i t h n a t i o n a l g o v e r n m e n t s t o c i r c u l a t e g u i d e l i n e s t o m e d i c a l
p r a c t i t i o n e r s and v e t e r i n a r i a n s on t h e c l i n i c a l and e p i d e m i o l o g i c a l m a n i f e s t a t i o n s o f v i r a l d i s e a s e s , s p e c i m e n s t o be t a k e n and a s e t o f a c t i o n s to be f o l l o w e d i n f u t u r e e p i s o d e s , s i m i l a r
t o what was g i v e n f o r E b o l a - l i k e d i s e a s e s . 1 6
3. WHO t o recommend c e r t a i n l a b o r a t o r y t e c h n i q u e s t o be u s e d i n c o l l a b o r a t i n g c e n t r e s f o r e f f i c i e n t v i r u s i s o l a t i o n and r a p i d i d e n t i f i c a t i o n . New s e r o l o g i c a l t e s t s such a s i n d i r e c t i m m u n o f l u o r e s c e n c e , r a d i o i m m u n o a s s a y and e n z y m e - l i n k e d immunoadsorbent a s s a y t o be a p p r a i s e d f o r u s e i n c o l l a b o r a t i n g c e n t r e s . Where n e c e s s a r y , an a d e q u a t e s u p p l y o f d i a g n o s t i c
s u b s t a n c e s t o be p r o v i d e d f o r i m p l e m e n t a t i o n o f t h e s e r e c o m m e n d a t i o n s .
4. To t r a i n r e s e a r c h e r s who a r e d i r e c t l y engaged i n a r b o v i r u s s t u d i e s i n the u s e o f t h e recommended p r o c e d u r e s t o e n s u r e r a p i d d i a g n o s i s o f v i r a l i n f e c t i o n s and p r o p e r e v a l u a t i o n o f e p i d e m i o l o g i c a l d a t a f r o m v a r i o u s l a b o r a t o r i e s . S i m i l a r l y , w o r k s h o p s t o be o r g a n i z e d f o r t h i s p u r p o s e .
5. WHO t o i n c r e a s e the number o f c o l l a b o r a t i n g c e n t r e s i n A f r i c a and s p o n s o r more r e s e a r c h p r o j e c t s on a r b o v i r u s d i s e a s e s .
6. WHO t o i n i t i a t e and promote j o i n t r e s e a r c h p r o j e c t s on v i r a l d i s e a s e s by a l l c o u n t r i e s i n e a c h r e g i o n f o r e c o n o m i c r e a s o n s and s c a r c i t y o f manpower and a l s o b e c a u s e the a c t i v i t i e s o f v i r u s e s and t h e i r v e c t o r s a r e n o t r e s t r i c t e d by g e o g r a p h i c a l b o u n d a r i e s . S i m i l a r l y , WHO
s h o u l d e n c o u r a g e i n d i v i d u a l c o u n t r i e s t o d i s s e m i n a t e t h e i r f i n d i n g s to o t h e r c o u n t r i e s i n t h e same o r d i f f e r e n t r e g i o n s f o r i n f o n n a t i o n and a c t i o n .
L a s s a , M a r b u r g and E b o l a
1 . A t e c h n i c a l team o f e x p e r t s t o be formed f o r w o r k i n g o u t a m u l t i d i s c i p l i n a r y a p p r o a c h i n p l a n n i n g r e s e a r c h p r o j e c t s and a d v i s i n g on c o n t r o l m e a s u r e s , i n c l u d i n g v a c c i n e p r o d u c t i o n a g a i n s t t h i s g r o u p o f d i s e a s e s .
2. A t h o r o u g h s e r o e p i d e m i o l o g i c a l s u r v e y t o be c o n d u c t e d i n a l l A f r i c a n S t a t e s to d e t e r m i n e t h e g e o g r a p h i c a l d i s t r i b u t i o n , r e s e r v o i r and a m p l i f y i n g h o s t s as w e l l as p o s s i b l e v e c t o r s i n v o l v e d . - ' 3. S a f e t y m a t e r i a l s and e q u i p m e n t , s u c h as gowns, g l o v e s , masks and c a p s and a l s o immune g l o b u l i n s a g a i n s t t h e s e v i r u s e s t o be s u p p l i e d t o c o l l a b o r a t i n g c e n t r e s as p r e c a u t i o n a r y
m e a s u r e s a g a i n s t a n o t h e r e p i d e m i c . \!
i
4. S p e c i a l c o n t a i n m e n t h o s p i t a l s and l a b o r a t o r i e s t o be s e t up i n each endemic r e g i o n t o m i n i m i z e r i s k s i n v o l v e d i n s e n d i n g o v e r s e a s s u s p e c t e d o r c o n f i r m e d c a s e s f o r t r e a t m e n t . 5. To p r e v e n t an a l a r m and t h e e x p e n s e s i n v o l v e d t n i n s t i t u t i n g p u b l i c h e a l t h measures a g a i n s t s u s p e c t e d VHF c a s e s , a l l o v e r s e a s p e r s o n s v i s i t i n g any s u b - S a h a r a n A f r i c a n c o u n t r y s h o u l d t a k e a d e q u a t e m a l a r i a p r o p h y l a x i s . 3
6. U n t i l a d e q u a t e i n f o r m a t i o n i s a v a i l a b l e on t h e r o l e o f v a r i o u s s p e c i e s o f mammals, b i r d s and r e p t i l e s i n t h e t r a n s m i s s i o n o f VHF, WHO s h o u l d o r d e r t h a t any o f t h e s e a n i m a l s be e x p o r t e d f r o m A f r i c a o n l y a f t e r b e i n g t e s t e d by s p e c i f i e d p r o c e d u r e s and f o u n d f r e e f r o m VHF v i r u s e s and a n t i b o d i e s .
YELLOW FEVER I N AFRICA: 19 7 7-1979
C o u n t r y
19 7 7 1978 1979
C o u n t r y
Case Death Case D e a t h Case Death
Gambia Ghana N i g e r i a S e n e g a l
110 33
30 219
30
40 494
11 1
120
T o t a l 110 33 249 70 506 120
Réf.: WHO Wkly e p i d e m . Rec. , 1980, _55 , 345-351
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