title: Evaluation of Plasmodium falciparum gametocyte detection in different patient material.
abstract: BACKGROUND
  For future eradication strategies of malaria it is important to control the transmission of gametocytes from humans to the anopheline vector which causes the spread of the disease. Sensitive, non-invasive methods to detect gametocytes under field conditions can play a role in monitoring transmission potential.
  
  
  METHODS
  Microscopically Plasmodium falciparum-positive patients from Jimma, Ethiopia donated finger-prick blood, venous blood, saliva, oral mucosa and urine samples that were spotted on filter paper or swabs. All samples were taken and stored under equal, standardized conditions. RNA was extracted from the filter paper and detected by real-time QT-NASBA. Pfs16-mRNA and Pfs25-mRNA were measured with a time to positivity to detect gametocyte specific mRNA in different gametocyte stages. They were compared to 18S-rRNA, which is expressed in all parasite stages. Results were quantified via a known dilution series of artificial RNA copies.
  
  
  RESULTS
  Ninety-six samples of 16 uncomplicated malaria patients were investigated. 10 (66.7%) of the slides showed gametocyte densities between 0.3-2.9 gametocytes/μl. For all RNA-targets, molecular detection in blood samples was most sensitive; finger-prick sampling required significantly smaller amounts of blood than venous blood collection. Detection of asexual 18S-rRNA in saliva and urine showed sensitivities of 80 and 67%, respectively. Non-invasive methods to count gametocytes proved insensitive. Pfs16-mRNA was detectable in 20% of urine samples, sensitivities for other materials were lower. Pfs25-mRNA was not detectable in any sample.
  
  
  CONCLUSIONS
  The sensitivity of non-invasively collected material such as urine, saliva or mucosa seems unsuitable for the detection of gametocyte-specific mRNA. Sensitivity in asymptomatic carriers might be generally even lower. Finger-prick testing revealed the highest absolute count of RNA copies per μL, especially for Pfs25-mRNA copies. The method proved to be the most effective and should preferably be applied in future transmission control and eradication plans. A rapid test for gametocyte targets would simplify efforts.
authors.forename: Katharina
authors.initials: K
authors.lastname: Kast
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Medical Centre of the University of Munich (LMU), Leopoldstrasse 5, 80802 Munich, Germany. berens@lrz.uni-muenchen.de.
authors.forename: Nicole
authors.initials: N
authors.lastname: Berens-Riha
authors.forename: Ahmed
authors.initials: A
authors.lastname: Zeynudin
authors.forename: Nuredin
authors.initials: N
authors.lastname: Abduselam
authors.forename: Teferi
authors.initials: T
authors.lastname: Eshetu
authors.forename: Thomas
authors.initials: T
authors.lastname: Löscher
authors.forename: Andreas
authors.initials: A
authors.lastname: Wieser
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shock
authors.forename: Michael
authors.initials: M
authors.lastname: Pritsch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008018:Life Cycle Stages / Q000235:genetics* / Q000502:physiology; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology; D015800:Protozoan Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
chemical_list: D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan