Full Length Research Paper

Mutations within folate metabolising genes of Plasmodium falciparum in Cameroon

Wilfred Fon Mbacham¹*, Marie-Solange Bebandoue Evehe¹, Palmer Masumbe Netongo¹, Innocent Mbuli Ali.¹, Nfor Emmanuel Nfor³, Ateh Isabel Akaragwe², Patrice Nsangou Mimche¹, Akindeh Nji¹, Cyrille Finyom Djoko¹, Bantar Tawe¹, Bidla Gawa², Theresia Asongna¹, Gang Boniface Toh¹, Barbara Atogho-Tieudeu¹, Nabi Nge¹, Raymond Ebeng⁴, John Ahmadou Mokube⁴, Christopher Kuaban⁵, Jean Bickii⁶, Veronique Penlap¹, Vincent Pryde Titanji² and Njifutie Njikam³

¹The Biotechnology Center, University of Yaounde I, Cameroon, P. O. Box 8094, Yaounde, Cameroon

²Biotechnology Unit, University of Buea , Cameroon.

³Department of Animal Biology and Physiology, University of Yaounde I, Cameroon.

⁴Bota District Hospital, Limbe South West Province, Cameroon.

⁵Faculty of Medicine and Biomedical Sciences and Jamot Hospital, Yaounde, Cameroon.

⁶Institute for Medical and Medicinal Plant Research (IMPM), Ministry of Scientific Research and innovation, Yaounde, Cameroon.

*Corresponding author. E-mail: wfmbacham@yahoo.com. Tel.: 77579180.

Fax: 22019778.

Accepted 20 July, 2009

   Abstract

Sulfadoxine-Pyrimethamine (S-P) still used in some parts of the country was suggested as the second line drug to amodiaquine following widespread failure of chloroquine in Cameroon in 2002.  We investigated the efficacy of S-P and determined the baseline mutations on marker genes for folate metabolism (dhfr and dhps) in the forest and Guinea-Savanna ecozones of Cameroon, as a way of tracking resistance in patients aged between 0.5 and  10  years in Limbe (n=138),  Nkambe (n=103), Fontem (n=100 ) and Dschang (n=93 ).  Filter paper blood sample were collected prior to treatment and on clinical failure days to determine the prevalence of molecular markers of resistance and to assess  the mutation rates on the folate metabolising genes by restriction fragment length polymorphism assays or dot-blot assays with 32-P labeled mutation-specific probes. Sequencing using the dideoxy-chain termination method by PCR was conducted to confirm doubtful cases. Late parasitological failure (LPF) was higher in Limbe (30.6%) compared to Nkambe 10.3% (p=0.001).  The prevalence of the 437-Gly mutation though lower in Nkambe, 57.6%, than in Limbe, 60% were statistically not different (p=0.2).  All genotypes with the 108N mutation also carried the 51-Ile and 59-Arg mutations. All sensitive alleles (S108) also carried the amino acids, 51-Asn and 59-Cys. S-P is no longer efficacious in Limbe and Nkambe, Cameroon for treating uncomplicated malaria in children below 10 years.  Instead 437G rather than the 108 N of Plasmodium falciparum may be determinant as the marker for tracking the spread of S-P resistance in Cameroon.

Key words: Mutations, plasmodium, sulfadoxine-pyrimethamine, resistance, dhfr, dhps