Intestinal helminth infections are associated with increased incidence of Plasmodium falciparum malaria in Thailand.
In a prospective study of the total population of 5 hamlets on the western border of Thailand, all subjects were screened for helminth infections; during the following year, the incidence of malaria was recorded. Patients were not treated for helminth infections. Among 731 villagers, helminth-infected subjects were more likely to develop falciparum malaria during the following year (adjusted risk ratio 2.24, range 1.4-3.6; P = 0.001). The risk of developing falciparum malaria increased with the number of helminth species (P =0.036). Whereas in other studies helminths were associated with protection from severe complications of malaria, it seemed here that helminth-infected patients were more likely to develop malaria. It is suggested that a helminth-mediated Th2 shift may have complex consequences on malaria, decreasing antisporozoite immunity, but protecting against severe malaria.
Nacher
M
M
Unité INSERM 511, Immunobiologie Cellulaire et Moléculaire des Infections Parasitaires, CHU Pitié-Salpétrière, Paris, France. m_nacher@lycos.com
Singhasivanon
P
P
Yimsamran
S
S
Manibunyong
W
W
Thanyavanich
N
N
Wuthisen
R
R
Looareesuwan
S
S
D000293:Adolescent; D000328:Adult; D000818:Animals; D001200:Ascaris; D005260:Female; D006801:Humans; D015994:Incidence; D007411:Intestinal Diseases, Parasitic / Q000150:complications* / Q000469:parasitology; D016778:Malaria, Falciparum / Q000453:epidemiology*; D016780:Malaria, Vivax / Q000453:epidemiology; D008297:Male; D009348:Nematoda / Q000145:classification / Q000302:isolation & purification*; D009349:Nematode Infections / Q000150:complications* / Q000469:parasitology; D011446:Prospective Studies; D012307:Risk Factors; D012424:Rural Population; D013321:Strongyloides; D013785:Thailand / Q000453:epidemiology; D014258:Trichuris