Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 18 3 2023 09 22 324 330 Fahimeh Kooshki Department of Pediatric Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran Amal Khudair Khalaf Department of Microbiology, College of Medicine, University of Thi-Qar, Nasiriyah, Iraq Hossein Mahmoudvand Hepatitis Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran Parastoo Baharvand Hepatitis Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran Faezeh Gandomi Rouzbahani Student Research Committee, Lorestan University of Medical Sciences, Khorramabad, Iran Behnoush Selahbarzin 1. Hepatitis Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran 2. Department of Pediatric Dentistry, School of Dentistry, Lorestan University of Medical Sciences, Khorramabad, Iran 2022 06 04 2023 01 22 Background: This survey was designed to study the molecular epidemiology and risk factors of Entamoeba gingivalis and Trichomonas tenax in children with underlying malignancies and those on chemotherapy in Lorestan province, West of Iran. Methods: The present cross-sectional descriptive study was performed on children who suffering from different types of malignancies or receiving treatment by chemotherapy referring to oncology section of hospitals of Lorestan Province, Iran during May 2021 to April 2022. The frequency of oral cavity protozoa was investigated using microscopic and conventional polymerase chain reaction (PCR). Results: E. gingivalis and T. tenax parasites were found in 23 (25.5%) by microscopic method and 28 (31.1%) using PCR in children with malignancy. Among positive samples, 20 (71.4%) were infected with E. gingivalis; whereas 8 (28.6%) of the participants were positive for T. tenax. In the multivariate model, living in rural regions (OR= 3.437; 95% CI= 1.22-9.63; p=0.019) and using mouthwash (OR= 0.082; 95% CI= 0.018-0.37; p<0.001) were significantly related with the frequency of oral cavity parasites. Conclusion: Our results showed the high frequency of oral cavity parasites in children who suffering malignancies or receiving treatment by chemotherapy in Lorestan province, Iran. The awareness of the main risk factors for oral cavity parasites particularly using mouthwash is necessary in improving public and oral health strategies in children with cancer. Consequently, oncologist and dental practitioners must be aware to identify and manage oral health concerns in in children who suffering from different types of malignancies to prevent the oral diseases and infections. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/3640 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/3640/1305