Rickettsia slovaca and R. raoultii in tick-borne Rickettsioses

Abstract

Tick-borne lymphadenopathy (TIBOLA), also called Dermacentor-borne necrosis erythema and lymphadenopathy (DEBONEL), is defined as the association of a tick bite, an inoculation eschar on the scalp, and cervical adenopathies. We identified the etiologic agent for 65% of 86 patients with TIBOLA/DEBONEL as either Rickettsia slovaca (49/86, 57%) or R. raoultii (7/86, 8%).

Figure 1

Dermacentor reticulatus, the ornate dog tick (A) (female, left; male, right), and D. marginatus, the ornate sheep tick (B) (engorged female, left; unfed female, center; male, right; scale bar = 1 cm), and their distribution. D. marginatus is most frequently found in Mediterranean areas of Europe with dense bush and tree cover and is common under oak and pine vegetation. It also has a restricted distribution in North Africa, in the cooler and more humid areas associated with the Atlas Mountains. Adults infest large mammals such as sheep, cattle, goats, and wild boars. Larvae and nymphs feed mostly on small mammals and medium sized carnivores. D. reticulatus is most frequently found in colder northern areas of western Europe and the former Soviet Union, with high humidity and mild winters. D. reticulatus is primarily a tick of dogs and carnivores, but it can be found on ungulates such as sheep, cattle, and horses (9). D. marginatus and D. reticulatus have been suggested as reservoirs of R. slovaca and R. raoultii, which are maintained in ticks through transstadial and transovarial transmission. Therefore, the geographic distribution of these rickettsiae likely parallels that of Dermacentor ticks (C).

Figure 2

Typical signs of TIBOLA (tick-borne lymphadenopathy)/DEBONEL (Dermacentor-borne necrosis erythema and lymphadenophy). Here, infections were caused by Rickettsia slovaca , resulting in cervical lymphadenopathy (left panel, arrow), inoculation on the scalp (middle panel), and residual alopecia 4 weeks later (right panel).