Serological study of rickettsia in Mongolian population

Abstract

Background: Rickettsia species are small, Gram-negative bacilli that are obligate intracellular parasites of eukaryotic cells and cause tick-borne rickettsiosis, a naturally occurring infectious disease. Rickettsia species are transmitted by the bite of infected ticks. Clinical symptoms include fever, a vesicular rash, inflammation of the lymph nodes, inflammation at the site of the tick bite, and headache. Materials and Methods: Our study carried out from 2016 to 2020 year, this was a cross-sectional study with individuals. A total of 4,724 participants were included, and study data were collected through laboratory tests and questionnaires. Five ml of blood was taken from the elbow vein and antibodies were determined according to the manufacturer’s instructions using the Spotted Fever Rickettsia EIA IgG, IgM Antibody album from FULLER laboratories. Logistic regression analysis and statistical processing of risk factors for tick-borne rickettsiosis were performed using R software. Results: Serology detected Rickettsia IgM in 14.5% (685/4724) and Rickettsia IgG in 21.8% (1032/4724), respectively. According to logistic regression based on serum IgG, the prevalence of tick-borne ricketsia infection was 29.2% (95% CI: 27.4-31.2%) in women and 25.8% (95% CI: 23.6-28.1%, [OR: 1.13, 95% CI: 0.981.31]), respectively. The prevalence of rickettsial disease was 31.9% (95% CI: 29.0-34.9; P<0.001) at ages 5-9 years, 33.0% (95% CI: 28.1-38.2; P<0.022) at ages 10-14 years, and 35.1% at ages 25-29 years. (95 CI: 28.1-42.6; P < 0.006) revealed a statistically significant difference. Positive cases of IgG antibodies to rickettsiae were detected in 28.6% in Ulaanbaatar and Zavkhan provinces, and in 14.3% in Bayankhongor, Huvsgul and Dornogovi provinces. 21.8% (1032/4724) of the rickettsia were detected in the serum of all individuals who participated in the study. Conclusions: Age, occupation, and place of residence are risk factors for rickettsia infection. Residents of Bayan-Ulgii, Bayankhongor, Bulgan and Darkhan-Uul provinces were 3-5 times more likely to be infected with rickettsia than residents of 21 provinces of Mongolia.