Plasmodium vivax malaria in Northwest Mexico

Background: In the last decade, around 80% of all cases of P. vivax transmission in Mexico had been reported in the southern states of Oaxaca and Chiapas. However, there is a transmission hotspot in northwestern part of the country, comprising the states of Chihuahua, Sinaloa, and Durango. In 2013, the state of Chihuahua Health Department reported that around 135,000 people from the municipalities of Batopilas, Chínipas, Guadalupe y Calvo, Guazapares, Morelos, Moris, Ocampo, Urique, and Uruachi lived in an area endemic of transmission. In addition, during that period, over 55,000 blood samples were collected, and 24,000 suspected cases were treated according to global guidelines. Despite these facts, little is known about overall P. vivax transmission in the Northern Pacific Coast including parasites genotypes and seroprevalence among the human population. Material and Methods: The aim of the proposal herein presented will focus on the efforts to locate, and evaluate the genotype of the parasites from the samples collected by the Health Department in the last five years. Moreover, we would like to evaluate by serology the presence of IgG antibodies against known malarial blood stage and sporozoite antigens such as MSP1, AMA-1 and CSP, in an effort to determine the prevalence of malaria transmission in the area. Results: Preliminary work used a limited number of P. vivax samples from the malaria focus comprising the state of Chihuahua. The genetic analysis by PCR / RFLP techniques and/or further sequencing of partial genes as csp, Pvs25, and SSU rRNA 18S, exposed P. vivax haplotypes distinct from those detected in southern Mexico. Conclusions: Back in the 1950s-70s, most of Mexico had malaria transmission, and it is possible that both parasites and humans moved freely across the Mexican territory. It wasn’t until the 1980s, where rationale efforts to control the disease were put onto practice, leaving residual malaria transmission foci, in which, differential parasite genotypes might prevailed and could be identified by polymorphic molecular markers.