title: High detection rate of Rickettsia africae in Amblyomma variegatum but low prevalence of anti-rickettsial antibodies in healthy pregnant women in Madagascar.
abstract: Tick-borne spotted fever group (SFG) rickettsioses are emerging infectious diseases in Sub-Saharan Africa. In Madagascar, the endemicity of tick-borne rickettsiae and their vectors has been incompletely studied. The first part of the present study was conducted in 2011 and 2012 to identify potential anthropophilic tick vectors for SFG rickettsiae on cattle from seven Malagasy regions, and to detect and characterize rickettsiae in these ticks. Amblyomma variegatum was the only anthropophilic tick species found on 262 cattle. Using a novel ompB-specific qPCR, screening for rickettsial DNA was performed on 111 A. variegatum ticks. Rickettsial DNA was detected in 96 of 111 ticks studied (86.5%). Rickettsia africae was identified as the only infecting rickettsia using phylogenetic analysis of ompA and ompB gene sequences and three variable intergenic spacers from 11 ticks. The second part of the study was a cross-sectional survey for antibodies against SFG rickettsiae in plasma samples taken from healthy, pregnant women at six locations in Madagascar, two at sea level and four between 450 and 1300m altitude. An indirect fluorescent antibody test with Rickettsia conorii as surrogate SFG rickettsial antigen was used. We found R. conorii-seropositives at all altitudes with prevalences between 0.5% and 3.1%. Our results suggest that A. variegatum ticks highly infected with R. africae are the most prevalent cattle-associated tick vectors for SFG rickettsiosis in Madagascar. Transmission of SFG rickettsiosis to humans occurs at different altitudes in Madagascar and should be considered as a relevant cause of febrile diseases.
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany; Institute for Virology, Philipps University, Marburg, Germany. Electronic address: christian.keller@staff.uni-marburg.de.
authors: Christian
authors: C
authors: Keller
authors: Military Hospital Hamburg, Hamburg, Germany.
authors: Andreas
authors: A
authors: Krüger
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Norbert Georg
authors: NG
authors: Schwarz
authors: University of Antananarivo, Antananarivo, Madagascar.
authors: Raphael
authors: R
authors: Rakotozandrindrainy
authors: University of Antananarivo, Antananarivo, Madagascar.
authors: Jean Philibert
authors: JP
authors: Rakotondrainiarivelo
authors: University of Antananarivo, Antananarivo, Madagascar.
authors: Tsiry
authors: T
authors: Razafindrabe
authors: Military Hospital Hamburg, Hamburg, Germany.
authors: Henri
authors: H
authors: Derschum
authors: Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Munich, Germany.
authors: Cornelia
authors: C
authors: Silaghi
authors: Comparative Tropical Medicine and Parasitology, Ludwig-Maximilians-Universität München, Munich, Germany.
authors: Daniela
authors: D
authors: Pothmann
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Alexandra
authors: A
authors: Veit
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Benedikt
authors: B
authors: Hogan
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Jürgen
authors: J
authors: May
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Mirko
authors: M
authors: Girmann
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Stefanie
authors: S
authors: Kramme
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors: Bernhard
authors: B
authors: Fleischer
authors: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany; Institute for Medical Microbiology, Justus Liebig University, Giessen, Germany.
authors: Sven
authors: S
authors: Poppert
mesh_terms: D000328:Adult; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D005260:Female; D006801:Humans; D026863:Ixodidae / Q000382:microbiology*; D008270:Madagascar / Q000453:epidemiology; D010802:Phylogeny; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood / Q000453:epidemiology / Q000382:microbiology*; D012281:Rickettsia / Q000235:genetics / Q000302:isolation & purification*; D012282:Rickettsia Infections / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial
keywords: Amblyomma variegatum; Madagascar; Rickettsia africae; Spotted fever group rickettsiae