Clustered Incidence of Leukocytoclastic Vasculitis and Purpura Fulminans: A Case Series of a Rare Dermatological Manifestation of Rickettsial Disease

Rickettsiae are a group of eukaryotic obligatory intracellular parasites with ticks and mites as vectors. Rickettsia conorii is the Indian counterpart of Rocky Mountain spotted fever causing the endemic variant - Indian tick typhus. This disease can cause severe illness in adults and children and can be missed despite the availability of serological tests. Initial screening for rickettsial diseases (RD) may include blood workup and a non-specific agglutination test, Weil-Felix (WF). In WF, agglutination against Proteus antigens is analyzed and can show false-negative results within the first week of presentation. Delayed immune reaction in patients with RD in the first week could also be responsible for negative specific IgM serology. The challenge for physicians is to differentiate between the two common diagnoses for fever with rash - viral exanthematous fever and rickettsial fever. By its endothelial cell tropism, RD rarely can lead to purpura fulminans, which is characterized by widespread progressive dermal vascular necrosis and hemorrhage. This case series demonstrates dermatologic presentations of rickettsial fever in three individuals from the same neighborhood within the same week. Based on serologic IgM levels, the patients were treated with doxycycline and made a full recovery. This case series aimed to highlight the need for awareness regarding the variable presentations of rickettsial fever including leukocytoclastic vasculitis and purpura fulminans.