Table 1.
No of subjects in each category and the prevalence (%) of the four species of helminths by age, sex, region and year
| No Subjects | Hookworms | T. trichiura | A. lumbricoides | H. nana | Combined | ||
|---|---|---|---|---|---|---|---|
| Age class Age (years) | |||||||
| 1 | 0-1 | 140 | 0 | 0 | 0 | 0 | 0 |
| 2 | 1.1 - 1.9 | 575 | 0 | 0 | 0.2 | 0 | 0.2 |
| 3 | 2.0 - 4.9 | 1084 | 0.1 | 0 | 0.1 | 0.1 | 0.3 |
| 4 | 5.0 - 9.9 | 903 | 0 | 0.1 | 0 | 0 | 0.1 |
| 5 | 10.0 - 14.9 | 423 | 0.2 | 0 | 0 | 0 | 0.2 |
| 6 | 15.0 - 19.9 | 297 | 1.0 | 0.3 | 0 | 0.7 | 1.7 |
| 7 | 20.0 - 29.9 | 1377 | 7.0* | 1.7 | 0.9 | 0.3 | 8.6 |
| 8 | 30.0 - 39.9 | 1345 | 4.6 | 0.6 | 0.7 | 0.1 | 5.3 |
| 9 | 40.0 - 49.9 | 1259 | 1.4 | 0.6 | 0.6 | 0 | 2.3 |
| 10 | 50.0 - 59.9 | 835 | 0.5 | 0.4 | 0 | 0.1 | 1.0 |
| 11 | 60.0 - 69.9 | 521 | 0.6 | 0.4 | 0 | 0 | 0.8 |
| 12 | 70.0 - 79.9 | 336 | 0.3 | 0 | 0 | 0 | 0.3 |
| 13 | > 79.9 | 113 | 0 | 0 | 0 | 0 | 0 |
| χ2 | 158.6 | 32.6 | 24.3 | - | ** | ||
| P | < 0.001 | 0.001 | 0.018 | NS | |||
| Sex | |||||||
| Males | 5327 | 3.4 | 0.7 | 0.5 | 0.1 | 4.2 | |
| Females | 3881 | 0.2 | 0.2 | 0.1 | 0.1 | 0.4 | |
| χ2 | 54.0 | - | - | - | ** | ||
| P | < 0.001 | NS | NS | NS | |||
| Region | |||||||
| Africa | 1299 | 0.2 | 0.1 | 0.1 | 0.2 | 0.5 | |
| Arabian Pen. | 511 | 0 | 0 | 0 | 0.2 | 0.2 | |
| Asia | 3214 | 5.7 | 1.4 | 0.9 | 0.2 | 7.2 | |
| Eastern Med. | 874 | 0 | 0 | 0 | 0 | 0 | |
| Qatar | 3310 | 0.1 | 0 | 0 | 0 | ||
| χ2 | 154.5 | 62.0 | 40.4 | 10.4 | 192.4 | ||
| P | < 0.001 | < 0.001 | < 0.001 | 0.035 | < 0.001 | ||
| Year | |||||||
| 2005 | 2559 | 1.0 | 0.3 | 0.2 | < 0.1+ | 1.3 | |
| 2006 | 2120 | 1.3 | 0.2 | 0.3 | < 0.1+ | 1.7 | |
| 2007 | 2220 | 3.1 | 0.7 | 0.5 | 0 | 3.7 | |
| 2008 | 2309 | 3.0 | 0.8 | 0.3 | 0.3 | 4 | |
| χ2 | 38.8 | 8.7 | - | 11.7 | 48.1 | ||
| P | < 0.001 | 0.034 | NS | 0.008 | < 0.001 | ||
*The highest prevalence in each category is in italics for emphasis.
+ In these cases there was just one infected subject.
** In this case see text for significant interactions between sex and age.
The statistical outputs were derived from minimum sufficient models, after first fitting all factors into a single full factorial model, and the degrees of freedom can be calculated from the number of levels within each factor minus 1. χ2 values are not shown for non -significant terms because these had been removed from the model during backward elimination in the derivation of the minimum sufficient model. The χ2 values for goodness of fit of the minimum sufficient models for hookworms, T. trichiura, A. lumbricoides and H. nana was as follows: 399.1 (dof = 838, P = 1), 368.9 (dof = 839, P = 1), 369.1 (dof = 842, P = 1) and 368.3 (dof = 851, P = 1), respectively. Additional terms in the final models, that did not incorporate the presence/absence of parasites are not shown, but can be made available on request from the authors.