Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory and hypercytokinemic syndrome associated with high morbidity and mortality that was first described by Scott and Robb-Smith in 1939 [1]. HLH is categorized into primary and secondary types based on different triggers. The diagnostic criteria were described by the Histiocyte Society (HLH-2004) [2]. Persistently activated CTLs and NK cells lead to cytokine storms, resulting in enhanced activation of macrophages and dendritic cells [1]. Secondary HLH (sHLH) is associated with infection, inflammation, and malignancy [3]. Triggering of HLH by intracellular pathogens is one of the most common forms of sHLH [3,4].

Human brucellosis is the most common bacterial zoonosis and is caused by Brucella spp. [5]. Brucella species can infect a host through various pathways. The pathogen penetrates and replicates within phagocytic cells, evades intracellular degradation, and overcomes the host immune system [6]. Clinical diagnosis of a patient is based on detailed patient interviews and epidemiological information. Laboratory diagnosis of brucellosis provides valuable information for clinicians to implement individualized treatment regimens and prognostic evaluations.

In this report, we present the case of an adult patient who was diagnosed with HLH which was associated with brucellosis. This case revealed that sHLH can occur in developing countries with intracellular pathogen infection. Early identification of the etiology of HLH should prompt clinicians to consider the therapeutic schedule and restraining the likelihood of infectious pathogen transmission.