Abstract
Blood-stage level Plasmodium falciparum infection (parasitemia density) is generally elevated prior to, or at the time of, clinical presentation of severe pediatric malaria episodes. Intensity of exposure to infective Anopheles mosquito bites is a suspected determinant of higher density parasitemia. Analyses of entomologic and parasitologic data collected in 1986-1987 were conducted to investigate whether the dose of infective bites predicted the incidence or degree of P. falciparum parasitemia in Kenyan children <6 years old. At 21 consecutive 30-day intervals, a new cohort (n ≃ 50 each) was enrolled, cured of malaria parasites, and monitored over 84 days for recurrent parasitemia. Outcomes included time to parasitemia, time to parasitemia ≤5,000/μl, and parasitemia density. Ecologic and individual- level analyses were conducted. The mean infective bite exposure experienced by each cohort was significantly associated with the incidence of parasitemia (age-adjusted r2 = 0.38, p = 0.022) and more strongly associated with the incidence of parasitemia ≤5,000/μl (age-adjusted r2 = 0.72, p < 0.001). The infective bite dose, analyzed as a time-dependent covariate, was associated with a 2.8 times higher rate of parasitemia ≤5,000/μl among children exposed to ≤1 infective bite per day as compared with the referent (rate ratio (RR) = 2.82, 95% confidence interval (CI) 2.24-3.56). Cumulative infective bite exposure, exposure duration, and age were significant predictors of recurrent parasitemia density in multiple linear regression analyses. The results support the contention that reductions in P. falciparum transmission intensity, in the absence of complete elimination, will reduce higher level parasitemia among African children.
| Original language | English |
|---|---|
| Pages (from-to) | 945-956 |
| Number of pages | 12 |
| Journal | American Journal of Epidemiology |
| Volume | 145 |
| Issue number | 10 |
| State | Published - May 15 1997 |
| Externally published | Yes |
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Keywords
- Anopheles
- Culicidae
- malaria
- Plasmodium falciparum
ASJC Scopus subject areas
- Epidemiology
Cite this
Dose- and time-dependent relations between infective Anopheles inoculation and outcomes of Plasmodium falciparum parasitemia among children in western Kenya. / McElroy, Peter D.; Beier, John C; Oster, Charles N.; Onyango, Fred K.; Oloo, Aggrey J.; Lin, Xihong; Beadle, Christine; Hoffman, Stephen L.
In: American Journal of Epidemiology, Vol. 145, No. 10, 15.05.1997, p. 945-956.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Dose- and time-dependent relations between infective Anopheles inoculation and outcomes of Plasmodium falciparum parasitemia among children in western Kenya
AU - McElroy, Peter D.
AU - Beier, John C
AU - Oster, Charles N.
AU - Onyango, Fred K.
AU - Oloo, Aggrey J.
AU - Lin, Xihong
AU - Beadle, Christine
AU - Hoffman, Stephen L.
PY - 1997/5/15
Y1 - 1997/5/15
N2 - Blood-stage level Plasmodium falciparum infection (parasitemia density) is generally elevated prior to, or at the time of, clinical presentation of severe pediatric malaria episodes. Intensity of exposure to infective Anopheles mosquito bites is a suspected determinant of higher density parasitemia. Analyses of entomologic and parasitologic data collected in 1986-1987 were conducted to investigate whether the dose of infective bites predicted the incidence or degree of P. falciparum parasitemia in Kenyan children <6 years old. At 21 consecutive 30-day intervals, a new cohort (n ≃ 50 each) was enrolled, cured of malaria parasites, and monitored over 84 days for recurrent parasitemia. Outcomes included time to parasitemia, time to parasitemia ≤5,000/μl, and parasitemia density. Ecologic and individual- level analyses were conducted. The mean infective bite exposure experienced by each cohort was significantly associated with the incidence of parasitemia (age-adjusted r2 = 0.38, p = 0.022) and more strongly associated with the incidence of parasitemia ≤5,000/μl (age-adjusted r2 = 0.72, p < 0.001). The infective bite dose, analyzed as a time-dependent covariate, was associated with a 2.8 times higher rate of parasitemia ≤5,000/μl among children exposed to ≤1 infective bite per day as compared with the referent (rate ratio (RR) = 2.82, 95% confidence interval (CI) 2.24-3.56). Cumulative infective bite exposure, exposure duration, and age were significant predictors of recurrent parasitemia density in multiple linear regression analyses. The results support the contention that reductions in P. falciparum transmission intensity, in the absence of complete elimination, will reduce higher level parasitemia among African children.
AB - Blood-stage level Plasmodium falciparum infection (parasitemia density) is generally elevated prior to, or at the time of, clinical presentation of severe pediatric malaria episodes. Intensity of exposure to infective Anopheles mosquito bites is a suspected determinant of higher density parasitemia. Analyses of entomologic and parasitologic data collected in 1986-1987 were conducted to investigate whether the dose of infective bites predicted the incidence or degree of P. falciparum parasitemia in Kenyan children <6 years old. At 21 consecutive 30-day intervals, a new cohort (n ≃ 50 each) was enrolled, cured of malaria parasites, and monitored over 84 days for recurrent parasitemia. Outcomes included time to parasitemia, time to parasitemia ≤5,000/μl, and parasitemia density. Ecologic and individual- level analyses were conducted. The mean infective bite exposure experienced by each cohort was significantly associated with the incidence of parasitemia (age-adjusted r2 = 0.38, p = 0.022) and more strongly associated with the incidence of parasitemia ≤5,000/μl (age-adjusted r2 = 0.72, p < 0.001). The infective bite dose, analyzed as a time-dependent covariate, was associated with a 2.8 times higher rate of parasitemia ≤5,000/μl among children exposed to ≤1 infective bite per day as compared with the referent (rate ratio (RR) = 2.82, 95% confidence interval (CI) 2.24-3.56). Cumulative infective bite exposure, exposure duration, and age were significant predictors of recurrent parasitemia density in multiple linear regression analyses. The results support the contention that reductions in P. falciparum transmission intensity, in the absence of complete elimination, will reduce higher level parasitemia among African children.
KW - Anopheles
KW - Culicidae
KW - malaria
KW - Plasmodium falciparum
UR - http://www.scopus.com/inward/record.url?scp=0030609547&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030609547&partnerID=8YFLogxK
M3 - Article
C2 - 9149666
AN - SCOPUS:0030609547
VL - 145
SP - 945
EP - 956
JO - American Journal of Epidemiology
JF - American Journal of Epidemiology
SN - 0002-9262
IS - 10
ER -