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Table 2 Parameters used for modelling the age distribution of infection, and the distribution of high intensity infections

From: Global numbers of infection and disease burden of soil transmitted helminth infections in 2010

Species

Age class (in years)

Age weight for prevalence

Aggregation parameter ( k)

Morbidity threshold1

 

Light intensity2

Medium intensity

High intensity

Hookworms

0-5

0.75

f(prevalence)3

1

2000

4000

 

5-10

1.2

f(prevalence)3

1

2000

4000

 

10-15

1.2

f(prevalence)3

1

2000

4000

 

15 plus

1.0

f(prevalence)3

1

2000

4000

A. lumbricoides

0-5

0.75

0.54

-

90

250

 

5-10

1.2

0.54

-

130

375

 

10-15

1.2

0.54

-

180

500

 

15 plus

1.0

0.54

-

180

500

T. trichiura

0-5

0.5

0.23

-

50

105

 

5-10

0.75

0.23

-

75

160

 

10-15

0.9

0.23

-

100

210

 

15 plus

1.0

0.23

-

100

210

  1. 1Intensity of infection for hookworm is expressed in terms of eggs per gram of faeces, for A. lumricoides and T. trichiura in worm burden. 2There is insufficient evidence to quantify the impacts of light intensity infection for A. lumbricoides and T. trichiura, and as such no disability weighting is applied to this group. 3Aggregation parameter is estimated as a function of prevalence (p) : k = 0.12p + 0.175p2 + 0.0008.