title: Malaria elimination challenges in Mesoamerica: evidence of submicroscopic malaria reservoirs in Guatemala.
abstract: Even though malaria incidence has decreased substantially in Guatemala since 2000, Guatemala remains one of the countries with the highest malaria transmission in Mesoamerica. Guatemala is committed to eliminating malaria as part of the initiative 'Elimination of Malaria in Mesoamerica and the Island of Hispaniola' (EMMIE); however, it is still in the control phase. During the past decade, the government strengthened malaria control activities including mass distribution of long-lasting insecticide-impregnated bed nets, early diagnosis and prompt treatment. This study aimed to determine the prevalence of malaria, including gametocytes, in three areas of Guatemala using active case detection (ACD) and quantitative polymerase chain reaction (qPCR).
  
  
  
  Cross-sectional surveys were conducted in three departments with varying transmission intensities: Escuintla, Alta Verapaz and Zacapa. Blood samples from 706 volunteers were screened for malaria using microscopy and qPCR which was also used to determine the prevalence of gametocytes among infected individuals. Results were collected and analysed using REDCap and R Project, respectively.
  
  
  
  Malaria was diagnosed by microscopy in only 2.8 % (4/141) of the volunteers from Escuintla. By contrast, qPCR detected a prevalence of 7.1 % (10/141) in the same volunteers, 8.4 % (36/429) in Alta Verapaz, and 5.9 % (8/136) in Zacapa. Overall, 7.6 % (54/706) of the screened individuals were positive, with an average parasitaemia level of 40.2 parasites/μL (range 1-1133 parasites/μL) and 27.8 % carried mature gametocytes. Fifty-seven percent (31/54) of qPCR positive volunteers were asymptomatic and out of the 42.6 % of symptomatic individuals, only one had a positive microscopy result.
  
  
  
  This study found a considerable number of asymptomatic P. vivax infections that were mostly submicroscopic, of which, approximately one-quarter harboured mature gametocytes. This pattern is likely to contribute to maintaining transmission across the region. Robust surveillance systems, molecular diagnostic tests and tailored malaria detection activities for each endemic site may prove to be imperative in accelerating malaria elimination in Guatemala and possibly across all of Mesoamerica.
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors: Shirley Evelyn
authors: SE
authors: Lennon
authors: Centro Nacional de Epidemiología (CNE), Guatemala City, Guatemala.
authors: Adolfo
authors: A
authors: Miranda
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors: Juliana
authors: J
authors: Henao
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors: Andres F
authors: AF
authors: Vallejo
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors: Julianh
authors: J
authors: Perez
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors: Alvaro
authors: A
authors: Alvarez
authors: Caucaseco Scientific Research Center (CSRC)/Centro Latino Americano de Investigación en Malaria (CLAIM), Cali, Colombia.|Facultad de Salud, Universidad del Valle, Cali, Colombia.
authors: Myriam
authors: M
authors: Arévalo-Herrera
authors: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia. sherrera@inmuno.org.|Caucaseco Scientific Research Center (CSRC)/Centro Latino Americano de Investigación en Malaria (CLAIM), Cali, Colombia. sherrera@inmuno.org.
authors: Sócrates
authors: 0000-0002-4688-0598
authors: S
authors: Herrera
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000962:Antimalarials / Q000627:therapeutic use; D001769:Blood / Q000469:parasitology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D060740:Disease Eradication; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D042241:Early Diagnosis; D005260:Female; D006166:Guatemala / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D009032:Mosquito Control / Q000379:methods; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D014838:Volunteers; D055815:Young Adult
chemical_list: D000962:Antimalarials
keywords: Asymptomatic; Gametocytes; Guatemala; Malaria; Mesoamerica; Plasmodium vivax; Prevalence; Submicroscopic