Spotted fever group rickettsiae in ticks feeding on humans in northwestern Spain: is Rickettsia conorii vanishing?
During a 7-year study, we identified and analyzed by PCR 4,049 ticks removed from 3,685 asymptomatic patients in Castilla y León (northwestern Spain). A total of 320 ticks (belonging to 10 species) were PCR-positive for rickettsiae. Comparison of amplicon sequences in databases enabled us to identify eight different spotted fever group (SFG) rickettsiae: Rickettsia slovaca, Rickettsia sp. IRS3/IRS4, R. massiliae/Bar29, R. aeschlimannii, Rickettsia sp. RpA4/DnS14, R. helvetica, Rickettsia sp. DmS1, and R. conorii. Although Mediterranean spotted fever (MSF) is an endemic disease in Castilla y León, R. conorii was found in only one Rhipicephalus sanguineus tick, whereas other pathogenic SFG rickettsiae were much more prevalent in the same area. Our data suggest that in Castilla y León, many MSF or MSF-like cases attributed to R. conorii could have been actually caused by other SFG rickettsiae present in ticks biting people in this region of Spain.
Fernández-Soto
Pedro
P
Laboratorio de Parasitología, Facultad de Farmacia, Universidad de Salamanca, Avenida Campo Charro s/n. 37007, Salamanca, Spain. pfsoto@usal.es
Pérez-Sánchez
Ricardo
R
Alamo-Sanz
Rufino
R
Encinas-Grandes
Antonio
A
D000818:Animals; D006801:Humans; D007299:Insect Bites and Stings / Q000382:microbiology*; D011156:Population Density; D012281:Rickettsia / Q000145:classification / Q000302:isolation & purification*; D012282:Rickettsia Infections / Q000453:epidemiology*; D013030:Spain; D013987:Ticks / Q000382:microbiology*