Objective: Brucellosis is still endemic in Iraq and the main source of public health risk; this study was performed to investigate the clinical signs and symptoms of Brucellosis and determine the hematological changes in the patients infected with Brucella which may assist in the rapid diagnosis of the disease.
Subjects and Methods: The study was performed in a period extending from (the first of January -2021to to the Third of June-2021). The data and blood samples were collected from (184) outpatients from a big hospital (Al-Sadder) in Missan Province infected with brucellosis aged between (10 - 65) years. the patients were diagnosed with brucellosis according to case history and clinical laboratory examination. The blood sample from each patient was divided into two test tubes, the first (2ml) for serological examination through separated the serum from the blood components and stored at (-18 °C) until analysis by using the Rose Bengal test. The hematological assessment was performed in the laboratory for each sample of blood (3 ml with EDTA) obtained from the patients infected with brucellosis. Complete blood counts were shown from the collected blood samples by automatic methods (System X kx-21n automated hematology analyzer; JAPAN CARE CO., LTD) including Hemoglobin (Hb), Leukocytes or white blood cells (WBCs), Platelets, Lymphocytes, and Neutrophiles.  Results: The disease was diagnosed in the patients by using the Rose Bengal test. the results observed a strong positive reaction for the patients infected with brucellosis, the majority and more than half of brucellosis cases were recorded in females (58.3%), and males (41.7%) of all cases. High incidence of brucellosis in the ages between (41-50) years (33.6%) cases, followed by the ages between (31 -40) years (31.1%) cases, while the lowest percentage infected with the disease was reported in ages between (10 -20) years in (8.1%) cases. The most common symptoms observed were fatigue (85.3%), fever (77.7%), arthritis (73.3%), sweats (69%), and headache (64.1%). The hematological analysis for the blood samples observed significant changes in (P<0.05) in leukocytes, leukocytosis (23.8%), leucopenia (12.2%), Anemia reported in (42.7%), Platelets also reported in abnormal value, thrombocytosis (15.1%), thrombocytopenia (11.1%) of all cases of brucellosis. lymphocytosis (32.7%), lymphocytopenia (15.5%)  ,while the neutrophils reported in abnormal ranges , neutrophilia (15.5%),neutropenia (11.6%) .Conclusions: the brucellosis prevalence as a zoonotic disease in rural areas in Missan and direct contact and handling of livestock make the females highly exposed to the risk of infection. The blood picture reveals hemolytic anemia, leukopenia, lymphocytosis, lymphocytopenia, and Neutrophils with neutropenia particularly when the disease is epidemiologically suspected.
Recommendations: Some of the population tend to rear animals inside the houses, which demanded specific authorities to take care control of the disease, especially in the animals that consider the main source of the disease.