Serra et al.
Seropositivity to Midichloria mitochondrii (order Rickettsiales) as a marker to determine the exposure of humans to tick bite
Pathog Glob Health 2019, 113: 167-172
The bacterium Midichloria mitochondrii is a tick-borne intracellular bacterium of the order Rickettsiales and is found with high prevalence in all life stages of Ixodes ricinus ticks. In female ticks, this bacterium is present to 100% (see Snapshot week 36/2018). M. mitochondrii is transmitted to the host during the blood meal, where it may replicate and induce specific antibodies. e.g. to the protein FliD. A total of 274 sera from patients were collected with different probability to have had contact with ticks – e.g. Lyme disease patients: very high, seropositivity to at least one tick borne pathogen, but Lyme disease negative: medium high, negative healthy controls: very low. Having analyzed five groups of patient sera for antibodies to FliD, there was a trend seen that the increase in seropositivity to M. mitochondrii was highly correlated with an increase in seropositivity and presence of clinical signs/symptoms for tick borne pathogens. The highest prevalence was found in Lyme disease patients (47.30%). The symbiont prevalence became lower as evidence of a tick bites became uncertain/almost uncertain (memory of a bite, or just symptoms) and the lowest results were registered in the negative controls (2.00%). According to these results, M. mitochondrii can be regarded as a useful source of antigens with the potential to be used to assess the exposure of humans to I. ricinus ticks.