Non-Random Distribution of Plasmodium Species Infections and Associated Clinical Features in Children in The Lake Victoria Region, Kenya, 2012-2018

Abstract

Background While Plasmodium falciparum (Pf) stands out as the most lethal malaria parasite species in humans, the impact of other species should not be dismissed. Moreover, there is a notable lack of understanding of mixed-species infections and their clinical implications.

Methods We conducted eight school-based cross-sectional malariometric surveys in the Lake Victoria region of western Kenya between 2012 and 2018. Plasmodium infection was determined by microscopy and nested polymerase chain reaction (PCR). The multiple-kind lottery (MKL) model calculated the expected distribution of Plasmodium infections in the population and compared it to observed values using a chi-squared test (χ2).

Results The Plasmodium prevalence by PCR was 51.1% (4969/9724). Among all infections, Pf, P. malariae (Pm), and P. ovale (Po) mono-infections were 58.6%, 3.0%, and 1.7%, respectively. Pf/Pm, Pf/Po, Pm/Po, and Pf/Pm/Po co-infections were 23.5%, 4.3%, 0.1%, and 8.6%, respectively. MKL modelling revealed non-random distributions with frequencies of Pf/Pm and Pf/Pm/Po co-infections higher than expected (χ2 = 3385.60, p < 0.001). Pf co-infections with Pm and Po were associated with a decreased risk of fever (aOR 0.64, 95% CI 0.46–0.83; p = 0.01) and increased risks of splenomegaly (aOR 12.79, 95% CI 9.69–16.9; p < 0.001) and anaemia (aOR 2.57, 95% CI 2.09–3.15; p < 0.001), compared to single-species infections.

Conclusion This study sheds light on the potential interaction between Pf and Pm and/or Po. Given the clinical significance of mixed-species infections, improved diagnostics, and case management of Pm and Po are urgently needed.