Mixed Plasmodium malariae Infections Were Underdetected in a Malaria Endemic Area in the Amazon Region, Brazil

Abstract

Plasmodium malariae infections are often asymptomatic and long-lasting. Mixed infections are often underdetected in areas where P. malariae, P. vivax, and P. falciparum are coendemic. In this study, we described the occurrence of these species circulating as single or mixed infections in Pará state, Brazil, in the Amazon region, with the purpose of clarifying the impact of misidentification of parasite species based only on morphological description using thick blood smear. By using real-time polymerase chain reaction based on the amplification of the mitochondrial DNA, we detected a prevalence of 46% (58/126) mixed infections with 33.3% P. malariae/P. vivax which were read as P. vivax monoinfections by microscopy detection. Our findings confirmed the high circulation of P. malariae in a malaria endemic area in the Brazilian Amazon region.

Association of apoptosis-related variants to malaria infection and parasite density in individuals from the Brazilian Amazon

“…As previously reported by our group [ 5 ], the malaria patients were subdivided into: (i) 42 individuals were mono-infected with P. falciparum ; (ii) 26 mono-infected with P. vivax ; and (iii) 58 individuals with mixed species of Plasmodium infection (42 had mixed-infection with P. vivax and P. malariae , 12 had mixed-infection with P. vivax and P. falciparum , and four patients were infected by the three species simultaneously).…”

“…Environmental conditions of the Amazon region are favourable to the circulation of parasites and their vectors, contributing to malaria being almost restricted to the Northern region of Brazil, where it is possible to find a significant percentage of mixed-species malaria infections [ 3 , 5 ]. In addition to these environmental factors, host genetic profile may modulate the immune response and influence the susceptibility to Plasmodium infection, and in the outcome of malaria [ 37 – 40 ].…”

“…According to the World Health Organization (WHO), malaria is still among the most prevalent parasitic diseases, with 247 million infections, and accounting for more than 600,000 deaths worldwide in 2021 [ 2 ]. In Brazil, the highest malaria burden and frequency is concentrated in the Amazon region [ 2 – 4 ], with the transmission of Plasmodium falciparum , Plasmodium vivax and Plasmodium malariae by mono or mixed infection caused by multiple species of Plasmodium [ 5 ].…”

Structural organization and sequence diversity of the complete nucleotide sequence encoding the Plasmodium malariae merozoite surface protein-1

“…Like other human malaria parasites, P. malariae has been incriminated in transfusion-transmitted malaria in which the prevalence seems to vary across endemic areas 12 , 13 . Meanwhile, the low parasite density of P. malariae among infected individuals has hampered efficient detection by conventional microscopy, especially when it co-infects with other malaria species 14 – 16 . On the basis of microscopy diagnosis, P. malariae infection accounted for approximately 0.1% of all malaria cases in Thailand 17 whereas PCR could diagnose about five times higher than microscopic examination 15 , 18 – 20 .…”