When it comes to coinfections between worms and malaria,
Ascaris lumbricoides has been the most cited worm. Eight studies found that
Ascaris was associated with a reduction of malaria (incidence, prevalence or reduction of parasitemia)[
1,
2,
6‐
11], two studies found that
Ascaris was associated with an increase in malaria prevalence [
12,
13], and two studies found no relation to malaria [
4,
14]. For cerebral malaria or renal failure, two studies identified
Ascaris lumbricoides as the only individual worm associated with protection from severe malaria in adults [
3,
15]. One study observed an increase of severe malaria in
Ascaris-infected children [
16]. This study is often cited as an example that worms are bad for malaria, but the use of vomiting - which can be caused by
Ascaris- as a definition criteria of severe malaria is problematic [
17]. To summarize in even broader strokes, for
Ascaris, 10 studies observed protection from malaria, three found an increase of malaria and two found no association at all with malaria. Another approach to the question compiled national ecologic data on worm prevalence, malaria incidence, climate, and GDP per capita, showed a ten-fold increase in malaria incidence in equatorial climates, low GDP, and
Ascaris lumbricoides prevalence < 25% relative to prevalence ≥ 25% (submitted).