Historical overview and update on relapsing fever group Borrelia in Latin America

Abstract

Relapsing fever group Borrelia (RFGB) are motile spirochetes transmitted to mammalian or avian hosts through the bite of hematophagous arthropods, such as soft ticks (Argasidae), hard ticks (Ixodidae) and the human clothing lice. RFGB can infect pets such as dogs and cats, as well as birds, cattle and humans. Borrelia recurrentis, B. anserina and B. theileri are considered to have worldwide distribution, affecting humans, domestic birds and ruminants, respectively. Borrelia spp. associated with soft ticks are transmitted mainly by Ornithodoros ticks and thrive in endemic foci in tropical and subtropical latitudes. Nowadays, human cases of soft tick-borne relapsing fever remain neglected diseases in several countries, and the impact these spirochetes have on the health of wild and domestic animals is largely understudied. Human infection with RFGB is difficult to diagnose, given the lack of distinguishing clinical features (undifferentiated febrile illness). Clinically, soft tick or louse-borne relapsing fever is often confused with other etiologies, such as malaria, typhoid or dengue. In Latin America, during the first half of the twentieth century historical documents elaborated by enlightened physicians were seminal, and resulted in the identification of RFGB and their associated vectors in countries such as Mexico, Panama, Colombia, Venezuela, Peru and Argentina. Almost 80 years later, research on relapsing fever spirochetes is emerging once again in Latin America, with molecular characterizations and isolations of novel RFGB members in Panama, Bolivia, Brazil and Chile. In this review we summarize historical aspects of RFGB in Latin America and provide an update on the current scenario regarding these pathogens in the region. To accomplish this, we conducted an exhaustive search of all the published literature for the region, including old medical theses deposited in libraries of medical academies. RFGB were once common pathogens in Latin America, and although unnoticed for many years, they are currently the focus of interest among the scientific community. A One Health perspective should be adopted to tackle the diseases caused by RFGB, since these spirochetes have never disappeared and the maladies they cause may be confused with etiologies with similar symptoms that prevail in the region. Graphical Abstract

A Novel Relapsing Fever Group Borrelia Isolated from Ornithodoros Ticks of the Brazilian Caatinga

“…Although tick-borne relapsing fever was first reported during the 19th century, it remains neglected as a human disease and little is known on its maintenance in ticks and vertebrates [ 7 , 8 ]. In South America, only two Ornithodoros -associated Borrelia species have been described, Borrelia brasiliensis and Borrelia venezuelensis ; the latter was associated with clinical cases of human relapsing fever in Colombia and Venezuela during the first half of the 20th century [ 11 ].…”

“…Subsequently, this isolate (designated as B. venezuelensis RMA01) was cultured in vitro and its genome sequenced [ 14 ]. Borrelia venezuelensis RMA01 constitutes to date the sole isolate of a RFG borreliae transmitted by an Ornithodoros tick in South America [ 11 ]. In a recent study, Muñoz-Leal et al [ 15 ] reported by molecular methods four novel RFG Borrelia genotypes in human-biting Ornithodoros ticks from Brazil: Borrelia sp.…”

Is Borrelia burgdorferi Sensu Stricto in South America? First Molecular Evidence of Its Presence in Colombia

“…The genus Borrelia (Spirochaetales: Borreliaceae) comprises about 43 recognized species of gram-negative motile spirochetes, ranging in length from 10-40 µm and 0.2-0.5 µm in diameter [1][2][3][4]. Borrelia are obligate vector-borne parasites that infect a wide diversity of vertebrate hosts, such as birds, reptiles, and mammals, including human as an accidental host [5][6][7][8].…”

“…Similarly, relapsing fevers (RF) are infectious, neglected, and emerging diseases in the Americas and in some African countries, caused by 21 recognized species [4,25,26]. Vectors involved in the transmission cycle of relapsing fevers are mainly soft ticks of the genus Ornithodoros (Argasidae), hard ticks of the genera Amblyomma, Dermacentor, Ixodes, and Rhipicephalus, the human body louse or clothing louse Pediculus humanus humanus, the latter vector of Borrelia recurrentis [4,5,[27][28][29][30][31][32]. Borrelia of the RFG exhibit transovarial and transstadial transmission in ticks, highlighting the importance of these vectors in the enzootic and epizootic cycles of the disease [4,29,32].…”

“…Vectors involved in the transmission cycle of relapsing fevers are mainly soft ticks of the genus Ornithodoros (Argasidae), hard ticks of the genera Amblyomma, Dermacentor, Ixodes, and Rhipicephalus, the human body louse or clothing louse Pediculus humanus humanus, the latter vector of Borrelia recurrentis [4,5,[27][28][29][30][31][32]. Borrelia of the RFG exhibit transovarial and transstadial transmission in ticks, highlighting the importance of these vectors in the enzootic and epizootic cycles of the disease [4,29,32]. In addition, hosts and reservoirs of Borrelia of the RFG include rodents, opossums, and bats [30,32]; except for Borrelia duttoni, which is only known in humans as natural hosts [27].…”