Comparison of Plasmodium ovale curtisi and Plasmodium ovale wallikeri infections by a meta-analysis approach

Abstract

Malaria caused by Plasmodium ovale species is considered a neglected tropical disease with limited information about its characteristics. It also remains unclear whether the two distinct species P. ovale curtisi and P. ovale wallikeri exhibit differences in their prevalence, geographic distribution, clinical characteristics, or laboratory parameters. Therefore, this study was conducted to clarify these differences to support global malaria control and eradication programs. Studies reporting the occurrence of P. ovale curtisi and P. ovale wallikeri were explored in databases. Differences in proportion, clinical data, and laboratory parameters between the two species were estimated using a random-effects model and expressed as pooled odds ratios (ORs), mean difference (MD), or standardized MD depending on the types of extracted data. The difference in geographical distribution was visualized by mapping the origin of the two species. A total of 1453 P. ovale cases extracted from 35 studies were included in the meta-analysis. The p-value in the meta-analyses provided evidence favoring a real difference between P. ovale curtisi malaria cases (809/1453, 55.7%) and P. ovale wallikeri malaria cases (644/1453, 44.3%) (p: 0.01, OR 1.61, 95% CI 0.71–3.63, I2: 77%). Subgroup analyses established evidence favoring a real difference between P. ovale curtisi and P. ovale wallikeri malaria cases among the imported cases (p: 0.02, 1135 cases). The p value in the meta-analyses provided evidence favoring a real difference in the mean latency period between P. ovale curtisi (289 cases) and P. ovale wallikeri malaria (266 cases) (p: 0.03, MD: 27.59, 95% CI 1.99–53.2, I2: 94%), total leukocyte count (p < 0.0001, MD: 840, 95% CI 610–1070, I2: 0%, two studies) and platelet count (p < 0.0001, MD: 44,750, 95% CI 2900–60,500, I2: 32%, three studies). Four continents were found to have reports of P. ovale spp., among which Africa had the highest number of reports for both P. ovale spp. in its 37 countries, with a global proportion of 94.46%, and an almost equal distribution of both P. ovale spp., where P. ovale curtisi and P. ovale wallikeri reflected 53.09% and 46.90% of the continent’s proportion, respectively. This is the first systematic review and meta-analysis to demonstrate the differences in the characteristics of the two distinct P. ovale species. Malaria caused by P. ovale curtisi was found in higher proportions among imported cases and had longer latency periods, higher platelet counts, and higher total leukocyte counts than malaria caused by P. ovale wallikeri. Further studies with a larger sample size are required to confirm the differences or similarities between these two species to promote malaria control and effective eradication programs.

Malaria parasite species composition of Plasmodium infections among asymptomatic and symptomatic school-age children in rural and urban areas of Kinshasa, Democratic Republic of Congo

“…Among children infected with P. ovale spp., we found 75%, 24% and 1% children harboured P.ovale curtisi , P. ovale wallikeri and mixed P.ovale curtisi + P. ovale wallikeri . This finding highlights the fact that P. ovale curtisi appears to be more prevalent than P. ovale wallikeri [ 72 ]. This is the first report of P. ovale curtisi in DRC; prior to this study only P. ovale wallikeri has been reported [ 24 ].…”

Malaria Infection and Risk for Endemic Burkitt Lymphoma: A Systematic Review and Meta-Analysis

“…Random-effects meta-analysis was used to summarize (1) the association between malaria infection and the odds of eBL, and (2) the association between the increased titer of IgGs to malarial antigens and the odds of eBL. The level of heterogeneity among the odds of each study was assessed using Cochran's Q statistic and I 2 .…”

“…Malaria is caused by one of the six Plasmodium spp. including P. falciparum , P. vivax , P. malariae , P. ovale curtisi , P. ovale wallikeri , and P. knowlesi [ 1 ]. Malaria and its mortality mostly occur in children aged below 5 years from 31 African countries [ 2 ].…”

Prevalence of malaria and scrub typhus co-infection in febrile patients: a systematic review and meta-analysis

“…Blood-feeding Anopheles mosquitoes transmit malaria by one of the six Plasmodium species, P. falciparum , P. vivax , P. malariae , P. ovale curtisi , P. ovale wallikeri , and P. knowlesi ; however, some zoonotic Plasmodium species, such as P. cynomolgi and P. simium , have been associated with human cases of malaria [ 1 – 5 ]. In a high transmission area, malaria is a major cause of death in children under 5 years because they lack immunity against malaria parasites; malaria is less common in older children and adults because of partial immunity [ 6 ].…”