The clinical characteristics and outcomes of patients with human granulocytic anaplasmosis in China.

OBJECTIVES

The incidence of human granulocytic anaplasmosis (HGA), a tick-borne disease caused by the obligate intracellular bacterium Anaplasma phagocytophilum, has increased across the world. However, information on HGA is lacking in China. The purpose of this study was to investigate the clinical features and outcomes of HGA patients in China.

METHODS

A total of 83 patients with HGA from the provinces of Hubei and Henan in China, who were admitted to Union Hospital between March 2009 and September 2010, were included in this study. We investigated the epidemiology, clinical features, laboratory markers, and therapeutic effects in these patients. We also analyzed life-threatening complications such as systemic inflammatory response syndrome (SIRS)/multiple organ dysfunction syndrome (MODS) following HGA and assessed the risk factors for a poor clinical outcome.

RESULTS

In our study, an HGA outbreak peak was observed for the months May to August. The highest age-specific incidence occurred among the group of patients aged 50-59 years. With regard to patient occupation and pathological origin, we found that 73 of the 83 patients with HGA had a peasant occupation. With respect to symptoms, 45 patients had no complications and 38 patients diagnosed with HGA met SIRS criteria, of whom 25 rapidly developed MODS. The mortality for the entire cohort was 26.5%. The factors predictive of patients developing MODS and an adverse outcome were advanced age, disturbance of consciousness, highly elevated lactate dehydrogenase, creatinine, and aspartate aminotransferase levels, and the presence of SIRS. Moreover, MODS was found to be an independent predictor of death.

CONCLUSIONS

In China, HGA patients had severe clinical symptoms and high rates of complications and mortality. These findings may provide useful information so that physicians will be on the alert for severe complications after a diagnosis of HGA; they will also be useful for optimizing supportive care for HGA-related critical illness. Prompt treatment and close monitoring of severe complications such as SIRS and MODS are of great importance in saving patient lives.