Unsuspected Rickettsioses among Patients with Acute Febrile Illness, Sri Lanka, 2007 - Vol. 18 No. 5 - May 2012 - Emerging Infectious Disease journal - CDC
Volume 18, Number 5—May 2012
Unsuspected Rickettsioses among Patients with Acute Febrile Illness, Sri Lanka, 2007
Suggested citation for this article
Globally, rickettsioses are increasingly recognized as causes of undifferentiated fever. Paired serum samples are infrequently obtained, but testing acute-phase serum alone is insensitive (IgG is initially absent) and nonspecific (IgG can persist for years, and IgM results represent cross-reactions).
AbstractWe studied rickettsioses in southern Sri Lanka. Of 883 febrile patients with paired serum samples, 156 (17.7%) had acute rickettsioses; rickettsioses were unsuspected at presentation. Additionally, 342 (38.7%) had exposure to spotted fever and/or typhus group rickettsioses and 121 (13.7%) scrub typhus. Increased awareness of rickettsioses and better tests are needed.
Sentinel studies in Malaysia (1), Thailand (2), India (3), Laos (4), and Nepal (5) suggest that scrub and murine typhus are frequent and that misdiagnosis as enteric fever results in ineffective therapy (5). Unrecognized rickettsial species are likely present in Sri Lanka, an island connected to the southern tip of India by an underwater 30-km land bridge. Kularatne reported acute rickettsioses diagnosed by using only acute-phase serum IgM in 56 of 118 patients who had fever in hilly central Sri Lanka (6); another study in the Western Province confirmed few (5/31cases) of suspected rickettsioses (7). Both studies were limited by selective enrollment. To characterize rickettsioses among undifferentiated febrile illnesses in southern Sri Lanka, we prospectively studied patients who came to a large hospital.