Hematological predictors of increased severe anemia in Kenyan children coinfected with Plasmodium falciparum and HIV-1

Abstract

Malaria and HIV-1 are coendemic in many developing countries, with anemia being the most common pediatric hematological manifestation of each disease. Anemia is also one of the primary causes of mortality in children monoinfected with either malaria or HIV-1. Although our previous results showed HIV-1(+) children with acute Plasmodium falciparum malaria [Pf(+)] have more profound anemia, potential causes of severe anemia in coinfected children remain unknown. As such, children with P. falciparum malaria (aged 3-36 months, n = 542) from a holoendemic malaria transmission area of western Kenya were stratified into three groups: HIV-1 negative [HIV-1(-)/Pf(+)]; HIV-1 exposed [HIV-1(exp)/Pf(+)]; and HIV-1 infected [HIV-1(+)/Pf(+)]. Comprehensive clinical, parasitological, and hematological measures were determined upon enrollment. Univariate, correlational, and hierarchical regression analyses were used to determine differences among the groups and to define predictors of worsening anemia. HIV-1(+)/Pf(+) children had significantly more malarial pigment-containing neutrophils (PCN), monocytosis, increased severe anemia (Hb < 6.0 g/dL), and nearly 10-fold greater mortality within 3 months of enrollment. Common causes of anemia in malaria-infected children, such as increased parasitemia or reduced erythropoiesis, did not account for worsening anemia in the HIV-1(+)/Pf(+) group nor did carriage of sickle cell trait or G6PD deficiency. Hierarchical multiple regression analysis revealed that more profound anemia was associated with elevated PCM, younger age, and increasing HIV-1 status ([HIV-1(-) --> HIV-1(exp) --> HIV-1(+)]. Thus, malaria/HIV-1 coinfection is characterized by more profound anemia and increased mortality, with acquisition of monocytic pigment having the most detrimental impact on Hb levels.

Figure 1. Increased Anemia and Mortality in HIV-1(+) Children

Bars represent percentage of children with SA (left y-axis), while lines depicts mortality percentage (right y-axis) in each HIV status. Differences in the proportion of individuals with SA (P=0.020) and those deceased (P<0.001) were compared using Pearson's χ² test. Pair-wise comparison revealed significant differences between proportions of children with SA and mortality in the HIV-1(−)/Pf(+) vs. HIV-1(exp)/Pf(+) groups (P=0.045 and P<0.001, respectively) and HIV-1(−)/Pf(+) vs. HIV-1(+)/Pf(+) groups (P=0.008 and P<0.001, respectively). There were 13 (3.2%) HIV-1(−)/Pf(+), 6 (5.4%) HIV-1(exp)/Pf(+), and 8 (33.3%) HIV-1(+)/Pf(+) children that died within the three-month follow-up period after enrollment. SA (Hb <6.0g/dL) cases were as follows: 137 (35.2%) HIV-1(−)/Pf(+); 44 (41.1%) HIV-1(exp)/Pf(+); and 14 (63.6%) HIV-1(+)/Pf(+).

Figure 2. Increased Intraleukocytic pfHz in HIV-1(+) Children

Bars represent mean PCN/μL (black) and PCM/μL (grey) concentrations and are associated with the left y-axis, while percentage of children with intraleukocytic pfHz are depicted with a broken line (PCN) and grey line (PCM) and associated with the right y-axis. Differences in the proportion of individuals with PCN [9.4% HIV-1(−)/Pf(+), 4.5% HIV-(exp)/Pf(+), 20.8% HIV-1(+)/Pf(+); P=0.029] and PCM [48.3% HIV-1(−)/Pf(+), 48.2% HIV-(exp)/Pf(+), 54.2% HIV-1(+)/Pf(+); P=0.852] were compared using Pearson's χ² test, while PCN [HIV-1(−)/Pf(+), 0.24/μL; HIV-1(exp)/Pf(+), 0.16/μL; HIV-1(+)/Pf(+), 0.54/μL; P=0.249] and PCM concentrations [HIV-1(−)/Pf(+), 3.09/μL; HIV-1(exp)/Pf(+), 2.75/μL; HIV-1(+)/Pf(+), 4.13/μL; P=0.456] were compared across the groups using the Kruskal-Wallis test. Pair-wise comparisons were performed using either Pearson's χ² test, for categorical variables, or Mann-Whitney U, for continuous variables. A total of 30 monocytes and 100 neutrophils were examined per slide and expressed as a percentage of the counted monocytes and neutrophils, and then PCM and PCN concentrations were derived by multiplying the percentages by the total absolute monocyte and neutrophil counts, respectively.