Molecular Evidence for Flea-Borne Rickettsiosis in Febrile Patients from Madagascar.

Christian Keller,Denise Dekker,Gi Deok Pak,Florian Marks,Jürgen May,Ligia Maria Cruz Espinoza,Vera Von Kalckreuth,Jean Noël Heriniaina,Sven Poppert,Hagen Frickmann,Tsiry Razafindrabe,Raphaël Rakotozandrindrainy,Justin Im,Ralf Matthias Hagen,Jean Philibert Rakotondrainiarivelo,Norbert Georg Schwarz

doi:10.3390/pathogens10111482

Abstract

Rickettsiae may cause febrile infections in humans in tropical and subtropical regions. From Madagascar, no molecular data on the role of rickettsioses in febrile patients are available. Blood samples from patients presenting with fever in the area of the capital Antananarivo were screened for the presence of rickettsial DNA. EDTA (ethylenediaminetetraacetic acid) blood from 1020 patients presenting with pyrexia > 38.5 °C was analyzed by gltA-specific qPCR. Positive samples were confirmed by ompB-specific qPCR. From confirmed samples, the gltA amplicons were sequenced and subjected to phylogenetic analysis. From five gltA-reactive samples, two were confirmed by ompB-specific qPCR. The gltA sequence in the sample taken from a 38-year-old female showed 100% homology with R. typhi. The other sample taken from a 1.5-year-old infant was 100% homologous to R. felis. Tick-borne rickettsiae were not identified. The overall rate of febrile patients with molecular evidence for a rickettsial infection from the Madagascan study site was 0.2% (2/1020 patients). Flea-borne rickettsiosis is a rare but neglected cause of infection in Madagascar. Accurate diagnosis may prompt adequate antimicrobial treatment.

Highlights

Ct = cycle threshold, y = year, m = month, ID = identification number, temp. = temperature, R. = Rickettsia, Rick. = Rickettsia spp. These results provide a molecular confirmation of human-pathogenic rickettsiae for the first time in febrile patients from Madagascar
The present study shows for the first time, based on a real-time PCR screening for rickettsial DNA in febrile patients, that human-pathogenic, flea-borne rickettsiae are transmitted to humans in Madagascar
The present study found no evidence for spotted fever group rickettsiae in febrile patients

Summary

Introduction

Rickettsiae are arthropod-borne, obligate intracellular Gram-negative bacteria. They are divided into four groups: the largely tick-associated spotted fever creativecommons.org/licenses/by/ 4.0/). Group that encompasses >25 species (e.g., Rickettsia [R.] rickettsii, R. africae), the lice-/fleaassociated typhus group (e.g., R. typhi), the transitional group (e.g., R. felis, which is flea-associated) and the tick-associated ancestral group (e.g., R. bellii) [1,2]. But not all rickettsiae harbored by arthropods are well-known human pathogens, and their pathogenicity differs from species to species. Mountain spotted fever (RMSF), is endemic in the Americas and is transmitted by ticks of the genera Dermacentor and Rhipicephalus. RMSF is probably the most lethal rickettsiosis, with a case-fatality rate of >35% when treatment with doxycycline is delayed [3].

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