Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America

Abstract Background Human babesiosis, caused by intraerythrocytic protozoa of the genus Babesia (Piroplasmida, Babesiidae), is a globally emerging zoonosis transmitted primarily through Ixodes spp. ticks. Babesia microti, which is endemic particularly in the northeastern and midwestern United States...

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Main Authors: Xin-An Huang, Rong Xiang, Ru-He Liao, Yu-Bo Luan, Yi-Lin Zhao, Ji-Hu Yang, Chun-Feng Luo, Lin Huang, Luo-Yuan Xia, Dai-Yun Zhu, Yi Sun, Lei Wang, Jia-Fu Jiang
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Language:English
Published: BMC 2025-06-01
Series:Infectious Diseases of Poverty
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Online Access:https://doi.org/10.1186/s40249-025-01311-x
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author Xin-An Huang
Rong Xiang
Ru-He Liao
Yu-Bo Luan
Yi-Lin Zhao
Ji-Hu Yang
Chun-Feng Luo
Lin Huang
Luo-Yuan Xia
Dai-Yun Zhu
Yi Sun
Lei Wang
Jia-Fu Jiang
author_facet Xin-An Huang
Rong Xiang
Ru-He Liao
Yu-Bo Luan
Yi-Lin Zhao
Ji-Hu Yang
Chun-Feng Luo
Lin Huang
Luo-Yuan Xia
Dai-Yun Zhu
Yi Sun
Lei Wang
Jia-Fu Jiang
author_sort Xin-An Huang
collection DOAJ
description Abstract Background Human babesiosis, caused by intraerythrocytic protozoa of the genus Babesia (Piroplasmida, Babesiidae), is a globally emerging zoonosis transmitted primarily through Ixodes spp. ticks. Babesia microti, which is endemic particularly in the northeastern and midwestern United States, accounts for the majority of globally reported human cases. Recent studies highlight its spread to non-traditional regions and cross-border transmission, driven by climate change, blood transfusions and increased human mobility. Despite increasing reports of autochthonous B. microti infections in certain areas of China, imported cases remain critically underrecognized due to overlapping clinical manifestations with malaria and limited diagnostic awareness. Case presentation We report a diagnostically challenging case of acute B. microti infection in a 52-year-old Chinese woman, presenting with a sudden recurrent fever (39.0–41.0 °C), hemolytic anemia (hemoglobin 104 g/L), thrombocytopenia (platelet 78 × 109 /L) and splenic hypodense lesions on July 11, 2023, seven days after returning from a 14-day visit to rural Wisconsin, United States. Peripheral blood smears demonstrated characteristic intraerythrocytic ring forms (parasitemia: 7800 organisms/μl) and pathognomonic "Maltese cross" tetrads. Polymerase chain reaction (PCR) targeting the 18S rRNA gene confirmed B. microti infection (GenBank No. PP087232), showing 99.8% identity with the US-type strain Gray (AY693840) and the sequence obtained from a US travel-acquired case in Singapore (MK609547). The patient received intravenous clindamycin (600 mg twice daily), oral dihydroartemisinin (80 mg twice daily), packed red blood cell transfusions, and supportive care, ultimately achieving full recovery after 17 days. Conclusions This study documented the first imported cases of human babesiosis in China, emphasizing the need for heightened clinical and public health vigilance. Screening travelers from endemic areas presenting with fever or hemolytic anemia for Babesia, bolstering molecular diagnosis, improving transfusion safety, and intensifying regional surveillance are crucial in reducing underdiagnosis and preventing transmission. These measures are essential for controlling babesiosis in China. Graphical Abstract
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spelling doaj-art-d09ac5d595894765bb1e2e902fb994fc2025-08-20T03:21:05ZengBMCInfectious Diseases of Poverty2049-99572025-06-011411610.1186/s40249-025-01311-xBabesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of AmericaXin-An Huang0Rong Xiang1Ru-He Liao2Yu-Bo Luan3Yi-Lin Zhao4Ji-Hu Yang5Chun-Feng Luo6Lin Huang7Luo-Yuan Xia8Dai-Yun Zhu9Yi Sun10Lei Wang11Jia-Fu Jiang12Artemisinin Research Center, Guangzhou University of Chinese MedicineState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesArtemisinin Research Center, Guangzhou University of Chinese MedicineInternal Medicine, Beijing United Family HospitalState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesState Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical SciencesBeijing Institute of Tropical Medicine, Beijing Friendship Hospital, Capital Medical UniversityArtemisinin Research Center, Guangzhou University of Chinese MedicineAbstract Background Human babesiosis, caused by intraerythrocytic protozoa of the genus Babesia (Piroplasmida, Babesiidae), is a globally emerging zoonosis transmitted primarily through Ixodes spp. ticks. Babesia microti, which is endemic particularly in the northeastern and midwestern United States, accounts for the majority of globally reported human cases. Recent studies highlight its spread to non-traditional regions and cross-border transmission, driven by climate change, blood transfusions and increased human mobility. Despite increasing reports of autochthonous B. microti infections in certain areas of China, imported cases remain critically underrecognized due to overlapping clinical manifestations with malaria and limited diagnostic awareness. Case presentation We report a diagnostically challenging case of acute B. microti infection in a 52-year-old Chinese woman, presenting with a sudden recurrent fever (39.0–41.0 °C), hemolytic anemia (hemoglobin 104 g/L), thrombocytopenia (platelet 78 × 109 /L) and splenic hypodense lesions on July 11, 2023, seven days after returning from a 14-day visit to rural Wisconsin, United States. Peripheral blood smears demonstrated characteristic intraerythrocytic ring forms (parasitemia: 7800 organisms/μl) and pathognomonic "Maltese cross" tetrads. Polymerase chain reaction (PCR) targeting the 18S rRNA gene confirmed B. microti infection (GenBank No. PP087232), showing 99.8% identity with the US-type strain Gray (AY693840) and the sequence obtained from a US travel-acquired case in Singapore (MK609547). The patient received intravenous clindamycin (600 mg twice daily), oral dihydroartemisinin (80 mg twice daily), packed red blood cell transfusions, and supportive care, ultimately achieving full recovery after 17 days. Conclusions This study documented the first imported cases of human babesiosis in China, emphasizing the need for heightened clinical and public health vigilance. Screening travelers from endemic areas presenting with fever or hemolytic anemia for Babesia, bolstering molecular diagnosis, improving transfusion safety, and intensifying regional surveillance are crucial in reducing underdiagnosis and preventing transmission. These measures are essential for controlling babesiosis in China. Graphical Abstracthttps://doi.org/10.1186/s40249-025-01311-xHuman babesiosisBabesia microtiHemophagocytosisTravel-related diseases
spellingShingle Xin-An Huang
Rong Xiang
Ru-He Liao
Yu-Bo Luan
Yi-Lin Zhao
Ji-Hu Yang
Chun-Feng Luo
Lin Huang
Luo-Yuan Xia
Dai-Yun Zhu
Yi Sun
Lei Wang
Jia-Fu Jiang
Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
Infectious Diseases of Poverty
Human babesiosis
Babesia microti
Hemophagocytosis
Travel-related diseases
title Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
title_full Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
title_fullStr Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
title_full_unstemmed Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
title_short Babesia microti (Babesiidae, Piroplasmida) infection in a Chinese traveler returning from the United States of America
title_sort babesia microti babesiidae piroplasmida infection in a chinese traveler returning from the united states of america
topic Human babesiosis
Babesia microti
Hemophagocytosis
Travel-related diseases
url https://doi.org/10.1186/s40249-025-01311-x
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