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Understanding the population genetics of genes which shape resistance to antimalarial drugs can help in devising novel control strategies. The high spread of the resistant strains of the malaria parasite Plasmodium falciparum pose a greater challenge than before to the control programs across the world. Specific mutations in the P. falciparum chloroquine resistant transporter gene “ Pfcrt ” have been associated with resistance to not only chloroquine, but also to amodiaquine, one of the artemisinin partners used in Cameroon for the treatment of uncomplicated malaria. We here present data on genetic variation at the Single Nucleotide Polymorphisms (SNPs) level in the Pfcrt gene in five distinct geographical settings of the Southern-Cameroon (the most malaria endemic part), i.e. Ebolowa, Yaounde, Bertoua, Douala and Kye-ossi (a city bordering Cameroon and two others African countries). Two novel mutations, hitherto unreported (in Cameroon) were found in the Pfcrt gene and variable genetic diversity was observed across the populations. High linkage disequilibrium was found between few SNPs including one of the novel mutations suggesting a synergistic work for conferring/maintaining a higher level of resistance. The inference of evolutionary pattern of this gene in Cameroon based on the genetic diversity data depicts a signature of Darwinian positive natural selection on these loci. Observation of novel mutations might traduce new variants in chloroquine/or amodiaquine resistance (proposal awaiting an experimental verification) and signal of positive selection can be the result of drug pressure exerted by misuse of chloroquine (though officially banned from the country) and/or amodiaquine. Our findings thus, provide a baseline understanding of the evolution of a malaria drug resistant gene in Cameroon and suggest a successful establishment of chloroquine-resistant strains which requires urgent attention of the malaria control program in Cameroon. [ABSTRACT FROM AUTHOR]

The malaria parasite Plasmodium vivax is known to be majorly endemic to Asian and Latin American countries with no or very few reports of Africans infected with this parasite. Since the human Duffy antigens act as receptors for P. vivax to invade human RBCs and Africans are generally Duffy-negative, non-endemicity of P. vivax in Africa has been attributed to this fact. However, recent reports describing P. vivax infections in Duffy-negative Africans from West and Central parts of Africa have been surfaced including a recent report on P. vivax infection in native Cameroonians. In order to know if Cameroonians living in the southern regions are also susceptible to P. vivax infection, we collected finger-prick blood samples from 485 malarial symptomatic patients in five locations and followed PCR diagnostic assays with DNA sequencing of the 18S ribosomal RNA gene. Out of the 201 malaria positive cases detected, 193 were pure P. falciparum, six pure P. vivax and two mixed parasite infections (P. falciparum + P. vivax). The eight P. vivax infected samples (six single + two mixed) were further subjected to DNA sequencing of the P. vivax multidrug resistance 1 (pvmdr1) and the P.vivax circumsporozoite (pvcsp) genes. Alignment of the eight Cameroonian pvmdr1 sequences with the reference sequence showed high sequence similarities, reconfirming P. vivax infection in all the eight patients. DNA sequencing of the pvcsp gene indicated all the eight P. vivax to be of VK247 type. Interestingly, DNA sequencing of a part of the human Duffy gene covering the promoter region in the eight P. vivax-infected Cameroonians to identify the T-33C mutation revealed all these patients as Duffy-negative. The results provide evidence of single P. vivax as well as mixed malaria parasite infection in native Cameroonians and add knowledge to the growing evidences of P. vivax infection in Duffy-negative Africans.

Objectives: The main objective of this study was to unravel the distribution of different Pfcrt genotypes in the central, littoral, eastern and southern regions of Cameroon and also in locations bordering Gabon and Equatorial Guinea. This is because (i) the chloroquine-resistant malaria parasite Plasmodium falciparum shows a wide occurrence in Cameroon, (ii) mutations in the 72nd to 76th amino acid positions of the Pfcrt gene are known to confer resistance to chloroquine, and (iii) only a single chloroquine-resistant haplotype (C72V73I74E75T76) has so far been reported in Cameroon., Methods: We followed a molecular approach with DNA sequencing of the second exon of the Pfcrt gene to identify single nucleotide polymorphisms in 180 P. falciparum field isolates sampled in five different locations in Cameroon., Results: The chloroquine-resistant Pfcrt CVIET haplotype was most abundant, followed by the wild-type CVMNK haplotype. Five hitherto unreported chloroquine-resistant Pfcrt haplotypes were detected for the first time in Cameroonian P. falciparum, including the surprise appearance of the S(agt)VMNT haplotype., Conclusions: The high observed haplotype diversity of the chloroquine-resistant Pfcrt gene and the appearance of the S(agt)VMNT haplotype are daunting and can be attributed to drug pressure and/or the misuse of chloroquine and/or amodiaquine in Cameroon.