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Table 1 Individual exposure of villagers to S. damnosum s.l. in the rain forest and savannah.

From: Individual exposure to Simulium bites and intensity of Onchocerca volvulus infection

  

SAVANNAH

RAINFOREST

Age/Gender

Row

50/m

54/f

35/m

60/m

11/m

19/f

63/m

  

S.K.

N.A.

O.S.

C.K.

J.D.

P.D.

S.T.

Occupation

 

nightwatch

farmer

farmer

farmer

school boy

farming

farmer

Clothing1

 

lss, lt

sk, lss

lss, lt

lss, lt, sh, so

sh

sk, sss

lt, sss

Protection by clothing1 (estimate)

 

60%

30%

60%

100%

40%

30%

60%

Microfilarial load at iliac crest (mf/mg)

 

10

16

25

1

49

149

44

Number Simulium landing per day

a

8

4

25

0

269

82

114

proportion of flies that -

        

   - flew away unfed

b

.33

.33

.55

.0

.64

.15

.16

   - sucked successfully

c

.44

.07

.11

.0

.31

.12

.53

   - were killed before sucking

d

.0

.0

.10

-

n.d.

n.d.

n.d.

   - were killed after feeding

e

.23

.60

.24

-

n.d.

n.d.

n.d.

Flies per day on standard fly collector

        

   - caught near the "test-person"

f

10

9

21

222

141

157

175

   - caught at the river banc

g

172

40

89

158

202

183

237

Standard daily biting rate (at river)2

h

328

435

Standard daily transmission potential2

I

6,6

27,8

Actual Index of Exposure 3 (AIE)

j

3%

6%

10%

0%

89%

22%

25%

Effective Annual Transmission Potential 4

365ij

72

144

239

0

9031

2232

2537

  1. Results from three days of observation per "test-person".
  2. 1: Clothing (estimate degree of protection; from [4]): lss - long sleeved shirt (5%); sss - short sleeved shirt (0%); lt - long trousers (30%); sh - shoes (30%); so - socks (30%); sk - skirt (20%);
  3. 2: Standard ABR and ATP, measured by the fly-collector at the river banc; data from [6] and [7].
  4. 3: Proportion of the biting rate on the person as compared to the biting rate on the fly collector at the river: j = a (c+e)/g in the savannah and a (c+k)/g in the rainforest; k: average of e (from savannah) = .36.
  5. 4: O. volvulus infective larvae per person and year i