- April IN -

-

a

WORLD HEALTH ORGAT.IIZATION ORGAI\IISATION MONDIALE DE T.A SANTE

ONCHOCERCIASIS CONTROL PROGRAMIIIE

IN

hIEST AFRICA

PROGRAMME DE LUTTE COT,ITRE LTONCHOCERCOSE EN AFRIQUE DE LIOUEST

EXPERT ADVISORY COMI,IITTEE

Eighth _session

15-19 June 1982

INFORMATION DOCIJMEI{T

EPIDEMIOLOGICAL EVALUATION .I,'NIT

Progress Report (June _1q86

- April

tqgTt

EPIDE}TIOIPGICAL EVALUAIION UIIIT

PROGRBSS REPORI (June 1986

- April

¹⁹⁸⁷⁾

fntrodrrct ion

fn order to

comply

with the

request

of the

EAC

Brain

storming session

that the

experts be more informed on OCP work we changed

the

format

of the

^EAC

report of this year.

fnstead

of a highlight of the Epi activities

and

results, the report will consist of all the

major

inEernal reports

from

the last

^EAC

to-date.

This

format, should

give a

beEter idea

of the

OCP working method and

of the

progress achieved

during the year.

The experts w111 decide

during

the meet,ing which reporEing formaE they

prefer or

^nhatever

other

adjustment they

feel j's _requlred to

improve communicat,ions.

Legend Summary

-

^{A note on}

^the latest

epidemiological

results ln the cert,ral

OCP area.

crit,eria for

selecEion

of Epi vilLages in the

sout,h-easEern zone.

- Quality

cont,rol

- Selection of villages -

^{Western zone}

-

Ophthalmological

activities

-

^Report on

the

mission

in

Pendie area.

Report on

the special studies

conducEed

in

Northern Ghana and Sout,hern

Burkina Faso

- Migration

st,udy

-

Xenodiagnostie.

a

a

Summarv

During 1986-87 working season

the

Epi

unit

has operat,ed

in the original

OCP zone,

the

SouEh-easE and West,ern

zones. fn addition, a

number

of

special

studies

were

carried

out.

Original

OCP zone

Routine evaluat,ions erere conducted

in

29

villages of the well

protecEed core

area,4 of

^which

in detail evaluations.

An overview

of

t,he resulEs

of this

area

is

^given

in

Appendix 1.

In the re-invasion

area

of Mali

we

are evaluating

11

villages.

Sout,h:East zone.

fn this

zone 18

vlllages

has been evaluated 11

of

^which

in detail

evaluation.

The

criteria of selection for

these

vlllages are given in

Annex 2.

West,ern zone

Quality ccnt.rol for

microscopy bet,ween OCP, Guinea and

Mali national

teams

has been

carried out

and

is

reported

in

Annex

3. Quality control

^between

OCP and

the

Senegal

national

t,eam

will

be execuE,ed before

the

end

of April.

fn order to define the

borders

of the

area

to

be

treated with larvicides

10

villages

were evaluat,ed

in

Guinea and 10

in Mali.

Since

the

emergence

of the

resisEance

crisis the

importance

of this

work has decreased.- The

selection of

lrestern

zone has

and

the

sampling 78

villages

from

to

be evaluaEed.

represenEat,ive

villages for the

epidemiological map

of

the been

completed. This

was

a

major undertaking

of

EPI/VCU/STAT

procedure

is

described

in detail in

Annex

4.

A

total of

Guinea,

Mali

and Senegal have been

or are in

E,he process ODhthalmology

-

^{A summary}

of the

ophthalmological

activities is

included

in

Annex 5.

Special

stu{ies

A survey

of the

area surr.ounding

the village of

Pendie was

carried

out.

in July

1986 and

is

report,ed

in

Annex 6.

A survey

of the

area surrounding

the village of

^{Goreba Somum has} been

carried out. This

survey was ext.ended

to

t,he Kulpawn,

l.lhite

Volr,a and

Sissili rlvers of

Northern Ghana and Southern Burkina Faso and

is

reported

in

Annex 7.

Surveys

of the

Yabo and

Suri

areas were conducted

folloring report of

presence

of biting flies linked to construction of a

^dam

or a bridge.

Ihe

results of the

^Yabo survey

are

reported

in the migration

study Annex 8

MigraLion study

of

NorEh,

East,

sout,h and west Burkina Faso has been

accomplished and

is

reporLed

in

Annex 8.

'...12

t

2

Xenodiagnostic study and comparison

of

^OCP standard method versus 24 hours

in saline

has been

carried

^ouE,.

PreparaEory survey

of the Bui

and Asubende areas have been conducted recenLly and

this information ls

incorporated

in the

respect,ive proposals.

The Farako study on

the effect of int,errupting

vect,or cont,rol

in

an area where

prevalence

and

intensity of infection in

man

are very

low because

of

^prolonged

vector control will

be undert,aken

this

summer.

r

^{Arlnexe 1}

EPIDEI{IOLOGICEL SITUATION IN TUE CEITTRAL OCP AREA

Sumary

of epldentological results

obtained betreen June 1986 and l{arch 1987.

BeEween June 1986 and March 1987, EPI has undertaken simple surveys

ln

²⁰

lndlcator vlllages ln

che cenEral OCP

area.

^FourEeen

of

these

vlllages

are

located ln

Burkina Faso

(3 fn the

Leraba/Comoe

trlangle, 2

along

the

upper Black

Volta

noE

far

frorn

the vllIage of

Pendle,

2

along che Bougourlba, 3

along

the

Red/tJhlEe

volta

and

4

along

the

Koulpeolgo) and

6 vlllages ln

Ghana

(4

_along Ehe sE,retch

of the

Black Volca whlch borders Burklna Faso

and

2

along Ehe

Otl

on

the

border wlch Togo).

t

I

2. Of the

2197

chlldren,

who were born

ln

^those

vlllages slnce the start of vector control

and exanlned

at least

once, none were found

to

be lnfect,ed,

agatnst

an expected number

of

355

lnfected chlldren

had

there

been no

vecEor

conErol.

The

total

^number

of chlldren ln the

124

lndlcator vlllages ln the

^cenEral OCP

area,

who were born

during the control perlod

and

for

whom O.volvulus

lnfectlon

has been demonsErat,ed

,

^stands

^therefore

^presenEly

stlll at 9 chi ren

compared

to

an expected number

of

^{about 800} lnfected

chlldren

(see

also table l).

3 The

longlcudinal _analysls of the

t,rends

ln

che ^CMFL has shown

that

the

results for

che trost, recenE surveys were

very satlsfacEory lndeed. In all the

terency

vlllages

t,he Ct'tFL has now

fallen

by more than 952, as can be

seen

for a

^group

of initially

holo-endemic

villages ln figure I

and

ln flgure 2 for a

group

of vlllages

from Ehe lower range

of

hyper-endemlclty.

The highesE CMFL recorded

during

che 1986/1987 surveys was

only 2.8

mfs.

Nearly

all

remainlng

skln snip poslt,lve

cases had

very

low

nfs

counts and

lC ls

^becomlng excepc,lonal

to find

patlenEs wlEh Eore than 30 mfs.

4

Figure I

and

flgure 2

demonsErate

also clearly

Ehe accelerated

decllne ln the

prevalence

in

cohorEs

of

adu1Es, and Ehe observed trends agree very

well with

t,hose predicted

with

Ehe host-parasiEe model

for

whlch che

quantiflcaEion

has

not

been

altered durlng

^Ehe lasE one and

a half

^year.

It is quite

remarkable

to find thls

uniform agreement, betrdeen observed and

predicced trends

for villages

from areas as wlde aparE as Ehe Leraba/Comoe

basin and t,he Red/WhlCe VolEa

baslns,

and

all the

laEest, Erends remaln

conslstent with the

assumpEion

of vlrt,ual lnterrupEion of

t,ransmlssion

during the control

perlod.

The

rapld decline ln the reservoir of lnfectlon ls

^now

also reflecced ln the cross-sectlonal

prevalences

of

rnfs

ln

Ehe

total populaElon.

Only Ehree

of the

twenEy

vlllages

had

a

prevalence

of

^more than 202 (1.e.21"11 281l and,

292

respectlvely).

BuE these

are vlllages

whlch were

lnlElally

holo-endemlc, wlEh

a pre-conrrol

CMFL

of

more than 50

mfs,

and

ihele

the prevalence

ls

^now

falllng very fast,

as shown

tf Flg.[.

6.

Noteworthy

are

Ehe good

resulcs for the

two

vlllages

along

the

Upper

Bougourlba

rlver. It

has been

long

suspecE.ed Ehat relnvasion had

rnalnt,alned an

signlflcanc

amount,

of

transmlsslon along

chls rlver

durlng

the flrst

^years

of control, whlle

uncerEalnty exlsEed abouc

the level of protectlon

achleved

ln thls

area

during the

subsequent perlod.

Epldemlologlcal

data for

prevlous surveys

(e.9. for

Nabere

ln Flg.l)

showed

a

delayed decrease

ln the

^CMFL whtch seemed Eo eonflrm chac slgnlflcanE transmlsslon had Eaken place

durlng

che

flrsc

^years

of control

along

thls rlver.

The maJor

fall ln

both

the

Ct"lFL and

the

prevalence over

the

lasc

three years ln

^Ehese two

vlllages ls therefore

beEter t,han expecced and Lc

would be

of speclal

lmport,ance

for long

term plannlng

of control ln

the

central

OCP area

lf

such favourable

results

would

also

be obtalned durlng

the

surveys planned

for the

Lower Bougourlba

lat,er thls

year.

5

L

7.

The epldemlologlcal nap

of

the OCP area has been modlfled

after taklng

Ehe

latest

epldemlologlcal

results lnto

accounE (see _aEtached

nap).

The major

nodlficatlon

concerns

the addltlon of

two

clusters with satisfactory

resulcs

along

the

Black

Volta

and

the

OEI

ln

Ghana,

but

Ehe general _pactern

for the

cent,ral OCP area remaLns

the

same as reported

ln

1986:

onchocerciasis dlsease and transmisslon appear

stl11 to

be under fu11

cont,rol

EhroughouE

the

area wlt,h Ehe exceptlon

of a

few

lsolated focl

^where

signlflcant resldual

Eransmlsslon has occurred.

8. Also the

epldemlologlcal

trends

conElnue st111 as predlcted and Ehe lagest

results

remaln conslst,ent

wlth

che hypothesis

of the vlrEual ellmlnatlon of

the reservolr of O.volvulus

infecElon

afcer

15 years

of vector control in

the central

oCp

aEil-

TABLE

I:

RESULTS OF SKIN-SNIP EKAI.{TNATIONS

IN

CHILDREN BORN SINCE THE START OF CONTROL a

RATIO OBS/EXP

(rn

z)

=g==== ===== === === == ==== = == == = ==== = ===== ===== =========== == ============== = ===

CENTRAL ^OCP

ooz ^L ooz 2

ooz ⁸ ooz ⁵

ZONE

NUMBER OF

VILLAGES WITH NUMBER

OF

^TNFECTED

VTLLAGES

CHILDREN

63 25 24

t2

I\ruMBER OF CHILDREN EXAMINED

4582 t777 2LL2 638

NUMBER OF

INFECTED CHILDREN

OBSERVED EXPECTED

4 0 4

I I

0 2

I

3r 20 2L 5

7.6 3.4 8.3 9.1

1.3 0.0

[.8

L.7 Subtotal t24

REINVADED OOZ-S IN THE UIEST

ooz

3

^1.3

ooz

4

^L2

9

4 7

4 9 r09

527 672

798. s

l.l

3 3

23.L I 10.5

l7 .3 6.3

Subtotal 25

REITIVADED OOZ.S IN THE EAST

0026

⁹

ooz

7

t3

6 I 199

tl

^{133. 6} 8.2

24 42 5

34 3

8

47r 679

20.5 7g.g

.3 .6

Subcocal 22 ll

¹¹⁵⁰

GRAT.ID TOTAL EXCLUDING INTERI'IEDIATE ZONE

39

100.3

^39.9

t7r

INTERMEDIATE ZONE

ooz

5

t3

GRAND TOTAL

2L I 1458

434

59 1032.4 5.7

3 49.6 6.0

3

184 24 I r892 62 108 2.0 5.7

Epidemiological tnends in the centnal ^0CP

^anea

Figure

1: Results fon holo-endemlc villages {pne-conEnol CMFL=65-75) 9

a x

a ^Eo I

E

Pnev a i ence XI

x

CMFL 100

90 80 70

v

60 50 40 30 20 r0 +to

E'f

lD

o

+tL .c.o o(J

c

Jll-

=

CJ EIc_(o x_c

o,C'

co, lo o,L o

(a

o Pnedtcted tnend:

-

(roll.l llnctl obsenved tnencl:

I

NIARBA

o

^TIERCOURA

X

NATIEOOUGOU

9

NABERE E

Pneva lence v

a

I a a v

a

I a 0 a

Figure

2:

Results fon hypenendemic

villages

(pnecontnol CMFL=20-301 100

\-- _<-o-

02458r01? 14 16 18

²⁰

Yeans

of

vecton contPol

-

PREDICTED TREND

v

o

OBSERVED TRENO

14 t6 t8

²⁰

Yeans

of

vecton contnol

+to

3e0

_(E

o80

IJL

.3

_o ⁷⁰

c,

c60 E50

J c, T'

840 5 E30 320

c

o,

gr0

c,L

o.o

024581012

B\\

\L. CMFL

\

a\

\

.\

\

b

t

a

,o _.cl 'r

o = o 7

,o _t. T .C(,

rn

T

ul ,TI

o

2 g

c)

o

D

:6'

m

t,

q z

cl

t,

g o :!

6 _z o

_'Yl

-

m

{

7t' m

z

c,ul

2

rfl

3 o

Tl

r

u

m C

r, vl

C

!

o i

! I, t-

(o

@

{ )

t

t

i

*0s0

i's r s * I

d6'o.I5P.

*[i';gg

9.-o A^

^o.

sEEeIt

flrro-Hg.

"ilgEE'd

3'dtireo

i.* - _H

_=.

i

o= t- ^I

oL

⁽⁾

= -o

g xf

-

_!J

.'E -

_o.

!-D_

a

r

C

l.E_rB

DE

e {@

n

ANNEX 2

Epr

vrif,fcEs

sELEcTEED FoR 1986-87 sEAsoN rN rHE SOUTH-EASTERN ZOI(E BY CRIIERIA _OF SNLECTION

CRITERIA

_{VILT,AGE NT,HBER}

To etudy

the effect of

drought on

the

transnlaelon and

fhe _ocular

_algns

of

onchocerclasla

in

an area

rlEhout vector

_control

ro

atudy

the

evolutron

of ocular

oncho under netural

condltl0n ln order to

complement

the

analyaia

of

the

.evaluatlon of

Oncho eye leeions.

To document

major dlfference in

^blindne sa

rate ln 2 vlllagea rlth

equal populatlon

slze,

prevalence _and CttFL

but dtfferent

vectorB.

To

compLete

the

geographlcal coverage

plus

document

the cllnlcal pattern of

^aquamqsum

transmlsslon in

^an

area where

vector control le

expected

to

be succesaful and

ln an

area shere

tt.is

expected

to

be

unauccessful.

To complete geograg,hlcal coverage

plus to

document

an area

of

extremely dangerous oncho

rrltt

Soubrenee

and

Sanctlpaull

slmullum speclee as vector.

To complete geographlcal

ior"..r" plus

lnvestigate

the aurprlslng flndlng of

very

hlgh

ATp and CUfl ulthouL bllndness

ln a

focue of.savanna vector epecles.

Geographlcal coverage

30-307-44L-306

442

tn detatl

+ 450

-

^L66

ln

almple.

30-307- 44t -306

442- 399-400-401 ln detall.

376

-

³⁷⁹

detall

14

detall

and 444 aimple

408 atmple

386 almple

Ner

vtllage ln the

^Daye

valley

^(Kurere) etrnple

During

thir ^rorking

^yerr

of rupervirlon of thc netionrl

teaos

rre rvailabte to drtc.

evrilrble for thc

^EAC oeeting.

EUALTTY CONTROL

qurllty _control rrl

^used

teal. 0nly recults of t Ihe resuylts of the

Seneg

Annex 3

thc llestern

eonc es 6ui nern and llal i tn nrt i

onal

teao ni I I

t

na be

in

he

rl

t ool

tional

fo!n3r ilrttonrl

tger

'Lrst ye.r

no

qurlity control test

H.s

carried out

betteen

the

Guinean

atcroscopists

end an ocP

technician.

Horevser

3 villages

evaluated

in

lggS

by

the 6uinean

table. xerc

llhereas re-evaluated by

the oicroscoPist

0cP

of staf{ in the

Guinean teara

1986. Ihe risults that

conducted

are

depicted

the

reading

in

Inein

the villages

Diaoorodou and Tere appears

to

be

a valid eleoent, the r,icroscopiit rorking in

Diaotadou

clearty is incornpetent. Also the visual aiurty

technician

operating in the village of

Tere appears

to

be

rather

useless.

"The rituation of the

6uinern

netionel

teaar eppearcd

critical et the

beginning of

the rorking

year _and

a

teea

of

one

professionalt

_one

oicroscopist

and one ophthataic

technicirn of

^OCP

ioined the

6uinean teao

at the

beginning

of its operation

io Noveober

1986. After

on-the-spot

supervision, it ras

decioeo

in collaboration...th the Chief o{ the

6uinean teao

to elioinate ₂

oeabers

of the

teara and

to train

ner

ones' After I

aonth

of collaborative effort, the results of the quality control

test

of gatisfyingr the 2 aicroscopiste

_see

Fig. t of

end

the 2.

Guinean

Further

teao versus supervision

the

_conducted OCp

technician are

by

the

saoe

certainly

0Cp teao

later.in the

year

confiroed the ioprorerent

achieved by

the

6uinean teao.

ir!_t_ Nr!!_eorl

-ter

ThiE teao nas tested year _one

of his

oicroscop

rrs

conducted betteen the

there is e

^good agreement

test, the

!lal i an reader d

Eecause an OCP versus OCp

resul

ts are

cl earl

y

super conc I ude

that

both l,lat i an

i

s

needed.

lrct

^year

rnd

denonetrated

satisfactory proficiency. _rhis ist las tested against

one 0cp

technician

and

later a

test

2

tlal i an ^rrri croscopi

sts.

rhe resul

ts

indi

cate that

rhereas betreen

the tro

r'ralian readers ^(see

Fig.3), in the

other oes oyerscore

the

OCp reader systeoatical I

y

^(See

_Fig.4).

quality control test ras also

done

at the

sane tirne and the

ior to that of the national _teao

^(See

Fig.S),

He can

readers

are at the

ooment over scoring _and

that retraining

F

@MPARISChI BEME.I GIEIIEn NATIoNAL

[E[]t

AIID ocp, C0H0R8 N[AtySrS

Dianaradou

-

Date

No.

^exam.

nev. (96)

o,rFL

Blintt f5)*

Sean

Gutnea

:

0cP

Gulnea 0cP

Guinea 0cP

o 0 25

25 85

86

65 65 85

86

0

9.4

44 85

e5

Diamad.ou

-

[6.r6

M

%.O g6.o

6?.I

84,,6

95.5

%.5

12.1 18.6

5.4 9.5

21.L

,7.4

0

0.9

a a

*

_The pranalence

of

^brindness

refer to

cross

sectional

d,ata and, the denoroinators

are d,lfferent.

Fig.1

Fig.2

A;r/fty cont"ol skln snp ?eadll brcltr

tor Onlane nrttcarl

t ta

{

aa

!a

I

o

,

i

aa

-,

rl

o

re tc

tt

l?

t!

t0 la

t! u tt

t0 c

t , t t

a

t I I

0

l0 t9

It

t

lc

t0 ta

It tt tt

r0 e

t , t

0 a

t t

t

o

0.0 r.0 a.0

^r.0

t.0 10.0

u.0

OGP

rrdc

ta.o tc.o lt.o

t0.0

Quallty control skln snp readl4g

&rultr lcr

Outsrt nttlosel

bra

a.e 10.0 tt o ta.o lt.o lt o

t0.0

Ocl

rrrdc

tr

g

tr tr tr

tr

tro

tr

tr

tr tr

tr

3r

tr otr

Ftr

tr

,. tr

tr tr

ll

E tr tr

tr o

o

t

_tr

ftr

tr

tr no@

trtr tr

t

tr

e.0 a0 cg

!.0

E

E] ii'l

Fig.

³

Fig .4

t

la

!

a a

I -

a

I

a

l0

a a

,

a 6 a

t

a

t

0

t

tr

Qualfty

controt skln snlp readl,g lrrsltr tc lrlt

leUsaet

brn

.C

Iell ndor I

Quallty

control sktn snp readl,E laulh

3or

ltll

Brttoa.l

t

rE

tr

€

_rtr

E

t

l0

2 0

E

t,

tr

tP

tr

o tr

tr

s

tr tr tc

ta

t

tc t0

1a

r!

l.l

It

l0 c a 7 a 0 a

t I I

0 ..

La

ta

-/ I

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I

ar0u

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rrdc

p

tr E

tr tr gtr

o

tr tr

Ei

tr D

o tr o

o tr

ooo

tr o

o tr

0tac ta ta tl

^r0

E

Fig.5

Quallty control skln snlp ?eadttg

&rul3r tor OGP

tmu

t0

!

! I B

u

tt It

1a

t8 t0 a c a

I

0

I

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t I

l, o

0 a

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a

E tr

f

tr

tr

gtr^OED

.vI t ry Annex 4

SELECTION OF VILLAGES

.

T{ESTERN ZONB

(\

Introductlon.

fhe eelectlon of the vlllages for

EPI

evaluatlon ln

the

llestem

zone Lg revlewed

taklng lnto

consideratlon

for the flret tlme the

conlng

of a drug,

Ivermect,ln,

eultable folnass treettrent.

The wldespread use

of thle drug, by

reduclng

nf

^loads

ln skln

and eyes w111

spoll

any

posetbtllty of longltudlnal

EPI

evaluatlon.

^The

prevlous systen

of selectlon

alned

at evaluatlng the

succesa

or fallure of

the

vector control effort,

becones obeolete and

a

new aysten based on

a

representative eaople alned

at

deecrlblng

the

conJolnt

effect of vector control

and oaee treatment u111 replace

Lt.

ObJecltve.'

-

^{To draw}

the epldenlologlcal

nap

of the

lleetern

2ine

baeed on

a

representatlve eaople

of vlllagee.

General ^S 1 Des llo

t. Stratlflcat,lon of

the Weatern Extenalon

ln

^zonee.

11. Betlnatlon of the rural

populatlon

of

each 2oo€.

llt.Mapplng of rlver stretches

and enpty arees

lnside

each zone.

lv.

Nurnberlng

of rlver

Btretcheo aod

""pty

^ER€8sr

vo

^Randon eelectr.on

of rlver

etretchee and enpty 8E€Eeo

vl. Dellmltatlon of

uhe area

allocated to a

aelected

rlver stretch or

enpty 8r€do

vll.Randon

eelectlon of vlllagee.

Detall

s'anpllng procedure.

I

^a

Stratlflcatlon of the llestern

extenslon

in

^zones.

The Western extenslon

ls

eubdlvlded

ln XVII

zonea by

ecologtcal,

entonologlcal and epldemlologlcal

crlterla,

6ee nap. The

caracterlstlcs of

each zone

ls

deplcted

ln table 1

and

2.

On

the

baee

of all

che

lnforuatlon avatlable

the

ecologlcal,

entomologlcal and

epldenlologlcal caracterletlce

coneldered are belleved

to

^be

largely unlforn

t

lthln 8

zon€o

11. Estlnatlon of the nrral

populatlon

of

each zoo€o

The

eetinatlon of the rural

populatlon

of

each zone

le

reported

ln table 3.

The

rural

populatlon

of a

zone

le

deflned aB

the total

populatlon

llvlng lnelde

a zone mlnus

the

populatlon

llvtng ln the dlstrlct capltala.

ll1.Mapplng

of rtvere

eectlone

lnalde

each zone.

The

rlvers of

each zone

are

dtvtded

ln

eectlone

of rlvers rlth hlgh

vector

productlon,

low

vector

productlon _and

ntl vector productlon. In addltlon

areaa rrlchout

rlvers

and

rlver

aectlons

slth nll vector

productlon

fora

eopty ar€ll8r

fhe dlfferentlatlon of vector

produclng and non

vector

^produclng

rlver

Bectlono

a

a

\ -2-

le

baeed on

the

_Presence

or

abeence

of

breedlng

eltes. the dlfferentlatlon of

vectoil ^produclng sectlons ae

hlgh

productlve _and low productlve

le

baeed on the Judgeoent and knonledge

of the 2

Eost experlenced entonologlsta

of the

l{estern

extentLon.

A ooq3 prectee

deflnlElon

could

not

be used becauee

of lneufflclent

daca.

lv.

Nuoberlng

of rlver

etretchee end eEpty erea8.

Rlver

eectlons

are

subdlvlded

ln

Btretchee

of

about,

5

koe

of lengih.

The exact

- dellaltatlon of the stretches ta

however lnfluenced

by the

need

of a clear

land

nark

such aB

the lneertlon of a trlbutary, or a

naJor bend

of the rlver.

Zonee

border.s, always

dellnlt a stretch;

country borders do

not.

Change

of

type

of stretch (hlgh' low, ntl vector

productlon) _alwaye

dellrall a atretch.

The atretchee

of

each zone

are

nuubered

starElng froo

one extreme

polnt

and

folloulng the rlvera flor.

Stretchee

are

nuubered by zone and

by

Lype

of atretch.

Eupty areas

are dlvlded ln

sectlong

of

about 6O

x

3o kms

or

45

x

45 kns dependlng

on

the

ehape and

are

numbered by

zone.

^Nunbered etretchee and enpty zonea are

vlsuatleed

on the nap.

vo

Randon eelect,ton

of rlver

etretchee and enpty 8r€B8r

The

rlver

sEretches and enpty areaa

are

eelecced uslng

a table of

randon numbers

and uelng alwaye

2 dlglte. _i

The

selectlon la

^done by zone and

the

nunber

of

Btretchee and eopty areas

eelect,ed

ls related to the slze of the rural

populatlon

of the

zones

as folloss:

Populatlon Stretches

Slze

Lese than 150.OOO

150.o00

-

^500.ooo

More than 500.000

hlgh

1 2 3

1 2 3

Etrptv areag 1i

I

2

(lf

presenE)

a

The zones

1 - 4,

12 and 16

are further

sub-dlvlded by

rtver baeln.

Zone

1 la dlvlded ln the 3 trlbutarlee of the

Senegal

rlver.

Zoae

4 le divlded tn

Faleme e

Gaoble

rlvers.

Zone L2

le dlvided ln

l{esc and East

alde.

Zone 16 1g

dlvlded ln westerly

bound

rlvers

and

the other.

The eelected etretchee and etrpty zones are

vlsuallsed

on Ehe oap.

vt. Dellultatlon of the

area

allocated to a

eelected

rlver

streEch

or

eEpty 8E€8o

Before proceedlng

to tire

choice

of vlllagee the

geographlcal areae allocat,ed ro each

stretch or

eEPty areaa

are ldentlfied

on 1/2OO.OOO nape ustng

the followlng rulee:

Stretcheg: The area

allocated to a

eelected

rlver etretch la

approxluaEely

rectangular in ahape.

The

2 longer

etdee

are traced paralle1 to the rtvei half ray

between

the

eelected

Btretch

and

the

nearest

one. fhe 2 ehort sldes

are

llolted by the

border

of

an empty area (10 kns

froo the laet

breedlng

etre)

and

or

an

other river. In the

case

of a

meetlng

of 2 rlvera

there

will

be an area

of 5

kns thaE can be asslgn

to both. Thls 5

koe area _{ehould be} asslgn

to the rlver stretch wlth hlgh vector

productLon

lf the 2

etretchee

dlffero

on

thls

^pa(aneter

or to the stretch of the

naJor

rlver lf

they

are

both

hlgh or both

low

v.ctor

produclng sEret,ches.

In

caee

of

conttguous Btretchee

of the

eane

type (hlgh

or

los

vect,or

productlon) _the

_{border between}

_the

gEretchee 1111 correepond

to

the border

of the

area

allocated to the seleited etretch.

3-

\

Enptv areaes EEPty areag

are llulted

by areas aeslgned

to rlver stretches

and

other

euPty

8r€8o Thelr etze ls

approxlnately 6O

x

30 kns

lf rectangular in

shape

or

⁴⁵

x

45 kus

lf equareo

^-

vll.Randou

eelectlon of vtllagee.

For

each

etretch of rlver 2 firet ltne

and

2 other

than

flret llne vlllages

are eelecEed uelng

a table of

randon

nuobers.

one

or tuo dlglta are

ueed accordlng

to the need. A flret llne vlllage le

deflned

as the vlllage closer to

^Ehe

rlver wlthln 5

kns

of lts banks.

Before selecLlon

all flrer llnI villagee

and

all other

than

firat

1lne

vlllagea are

separately numbered. The

villagee

eelected

are

reported

ln table

3.

Becauee

of

lnadequacy

of the

oape and ceneus data

a

number

of

amendoent

of

the eelected

vlllagee are foreeeen.

The aoendoenc ouat obey

the followlng ruleg.

Problea

1.

A

vlllage

haa changed naae

2.

A

vlllage

hae dleappeared

:

The

vlllage llsr

should be anended.

If the orher vllIage of the

BaEe caregory

(lst llne or other

than

flrst llne)

has a

populatlon

of

230

or

eore

inhabltants

the dlsappeared

village

should be dropped.

If

the

other vlllage

hae

a

populatlon

of lees

than 230 people

the

dlsappeared

vlllage

ehould be

replaced by

the

neareet

village of at

leaet

1OO people

of the

aaoe

caregory. If ln a rl- ver atretch

select,ed

there are only 2 villagee ln

one category both

are autonatlcally _:

eelected

but lf

one

of

theo hae dleappeared

it

cannot be replaced.

3 A

vlllage ta

unrepresentat,tve

Rule

o

4.

A

viUage

hae uneultable _elze

Vlllagee that are adnlnletrattve

cent,ers

(sous-prefecture)

or etth a

populatlon

of

oore than 800 people should

not

be parE

of

the

aaaple. If a village

presenta one

or

both these

caracterletlcs

ehould be dropped or replaced

followlng _the rules

expressed

ln

paragraph 2.

If a vlllage

hae

a

populatton

of

trore than ^4OO people

only a sectloo (quartlef)

_{should be}

eurveyed.

If a vlllage

hae

a

populatlon

of

^1OO

or

lese people an

extra vlllage

ahould be added, ae

secrlon (quartler), lf the

auo

of

the populatlons

of the 2 vlllagea origtnally

eelected

for the

category

la leee

than 23O

people.

_The

vlllage

added ehould be the neare8t one

to the eEall

aelected

vlllage

and

of the

aane calegory.

\

{ ^.,

?. J

\ -4-

If the

sun

of the

piipularton

of the 2 villages

aelected

ln the

category

is

230

or

Dore people no

addltlonal vlllage

ehould be

added. In

case

of

extreEe

results

(prevalence _)9OZ or

(52) a

popularlon

of

50

or

^Eore

lnhabltante le

coneldered

eufflclent

and no

extra vlllage

ehould be added.

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^Table. J

ZonePopula

I

550 000

u

100 @0

7ocr,o2

III

ZONE WEST

Selection of Villages

*

_{The nr.mbe}

_of

_v111a6es

_pres@t ln the rlver stretches ls

reported,

in

braket.

rr

River

stretches

Vector Size

of

village

ui$rtl

^row none

Iocatlon ln relation to

^breeding

site

Vl1lage naue Coordinates

2'

,9

10

26

,8

5

I

I

,

5

6 1

r(e)*

z

^(eo)

r

⁽⁺⁾

2 (te)

r ^(z)

z (t)

I ^(1r)

2

^(1e)

r ^(ro)

z ^(z) r(z) e (ra)

(ro)

( re)

KOUMUCOINI ttA}lAMBoucou

SEBEKORO

LI}IAKOLE MM,N[IAN

BAGA'IANEA l[A.I,IATAIA KOIITITOUGOIIN BADA

BAIANMUCOU 1[0U'10IINI KOUROI'NINKOIO BARANIAN

KOKOI'NKOI}TONDI KOKOIINKOIIIOBA FARABA NIAFAIA TINKO

DILIA KAIA DAIA

SAFINEBOUGOU KONKOU

UIBOIMOUIA FODBOUCOU DIOUCOUIITE KOBAMA.

TAMA NGANOU

12.19- g.rg

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DIAIAKA DIOI'NCOU DIAIAGA

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I.A ITA

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\

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ZONE

\

oPuls IV 240.000

.

VII

r50.000

VIII

296.000

Rtver

retc

^a _Locatlon

ln reiatton

to

breedlng

atte

^Vl1lage

name Coordlnatea Slze

of village

13 3

1

2

I

17 3

1

1

,

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