Rickettsiosis Caused by Rickettsia conorii in Uruguay

Abstract

The first three human cases of rickettsiosis caused by Rickettsia conorii in Montevideo, Uruguay were described in 1990. All of them showed an initial papulosquamous lesion on the scalp from a canine tick bite (Amblyomma triste). At the same time, fever and regional adenopathies were observed. Serological diagnosis was made by the indirect IgM immunofluorescent technique on glass smears of R. conorii (Biomerieux Laboratories, France). All patients had a benign disease course after been treated with oral tetracyclines. Other authors later developed clinical and serological studies for R. conorii rickettsiosis in a nearby county, confirming our original findings. The tache noir and a light exanthema were also noticed. We have seen several similar cases since that date. Most of them were from rural areas, and two presented with the classical tache noir and a maculopapular rash with severe symptomatology. A. triste, a South American tick with deep anthropophilia, appears as the usual transmitting vector of the disease in the country. A review of the literature reveals a very intriguing absence of similar cases in the Americas including the USA. New studies are necessary to resolve this issue. The possibility that a new species of rickettsia responsible for the disease in Uruguay is also considered.

Tick-Borne Rickettsioses around the World: Emerging Diseases Challenging Old Concepts

“…Preliminary studies also suggest that A. cajennense will support the growth and survival of R. parkeri (303), and a recent investigation has demonstrated DNA of R. parkeri in Amblyomma triste (formerly A. maculatum) ticks collected from humans and animals in Uruguay (347). These findings, coupled with other reports of escharassociated spotted fever rickettsioses in patients following bites of A. triste in Uruguay (73,87), suggests that R. parkeri rickettsiosis also occurs in areas of South America. In Uruguay, it is likely that rickettsiosis caused by R. parkeri has been diagnosed as infection with R. conorii based on nonspecific serologic tests (87).…”

“…These findings, coupled with other reports of escharassociated spotted fever rickettsioses in patients following bites of A. triste in Uruguay (73,87), suggests that R. parkeri rickettsiosis also occurs in areas of South America. In Uruguay, it is likely that rickettsiosis caused by R. parkeri has been diagnosed as infection with R. conorii based on nonspecific serologic tests (87).…”

“…During 1993During -1994 patients with a previous history of tick bite, including some with exanthems and inoculation eschars were identified from rural areas of Canelones County, Uruguay. These patients were also found to have titers reactive with R. conorii when tested by MIF; however, R. conorii was again the only antigen used in the assay (87). Amblyomma triste, a tick commonly found on dogs with a larval cycle on wild rodents, has been involved in these cases, and recently, R. parkeri has been isolated from this tick (347).…”

Rickettsia parkeriinAmblyomma tristefrom Uruguay

“…Neither rickettsial isolation nor polymerase chain reaction (PCR) amplification from human blood samples from patients from Uruguay have been performed. However, as has been suggested (8), other tick-transmitted rickettsiae could be present in Uruguay.…”

Tick-borne rickettsioses in America: Unanswered questions and emerging diseases

“…Therefore, serology should be considered as an initial, but not the sole, method to recognize and diagnose rickettsial diseases, particularly if no rickettsiae have been isolated or detected previously in the considered area. For example, several cases of SFG rickettsioses were described in Uruguay in the 1990s [50,51]. MIF serology using R. conorii as the sole antigen was used, and these infections were presumptively identifi ed as spotted fever caused by R. conorii.…”