Midichloriaceae (order Rickettsiales) is a recently described bacterial family named after Midichloria mitochondrii, the intracellular symbiont of the hard tick Ixodes ricinus (Sassera et al., 2006; Montagna et al., 2013). Midichloriaceae are comparable for variability and phylogenetic complexity to other two families of the order Rickettsiales: Rickettsiaceae and Anaplasmataceae, which include obligate intracellular bacteria causing various and important diseases in humans and other vertebrates (Parola and Raoult, 2001). However, in ecological terms, the family Midichloriaceae is possibly even more complex, since its hosts range from parasitic arthropods (ticks, fleas, bedbugs) to protist (ciliates and also pathogenic amoebae of the genus Acanthamoeba; Vannini et al., 2012; Schulz et al., 2015), also involving marine organisms such as Porifera and Cnidaria (Montagna et al., 2013). The association of Midichloriaceae with parasitic hosts suggests that bacteria of this family could be infectious to vertebrates and could be responsible for some medical and veterinary diseases. Direct and indirect evidence for the transmission of M. mitochondrii to humans and other mammals after the I. ricinus bite were indeed recently published: detection of M. mitochondrii DNA in vertebrate hosts and positivity in serological analysis using sera of parasitized humans and animals (Mariconti et al. 2012, Bazzocchi et al., 2013). M. mitochondrii, present in the ovary and in the salivary glands of I. ricinus females, might play a primary or secondary role in pathologies deriving from the tick bite. In addition, several lines of evidence suggest that other Midichloriaceae are infectious to vertebrates and that they could be responsible for disorders such as the red mark syndrome/strawberry disease in salmonids (Lloyd et al., 2008; Cafiso et al., 2015). However, the infectivity and pathogenicity of Midichloriaceae for humans/mammals has yet to be demonstrated, even if clinical cases compatible with rickettsiosis or ehrlichiosis in humans/animals parasitized by I. ricinus, but characterized by the absence of antibody titers for known pathogenic rickettsiae, could be re-investigated for the presence of signs of Midichloriaceae infections. In summary, several lines of evidence suggest the possibility that the family of Midichloriaceae could include infectious agents/pathogens for vertebrates.

Emerging pathogens in vertebrates: bacteria of the Midichloriaceae family (order Rickettsiales) / A. Cafiso, V. Serra, O. Plantard, D. Sassera, A.M. Floriano, C. Bazzocchi - In: Pathobiome: Pathogens in microbiotas in hosts : abstract book[s.l] : Muriel Vayssier Taussat, 2015. - pp. 1-1

Emerging pathogens in vertebrates: bacteria of the Midichloriaceae family (order Rickettsiales)

A. Cafiso
Primo
;
V. Serra
Secondo
;
D. Sassera;C. Bazzocchi
2015

Abstract

Midichloriaceae (order Rickettsiales) is a recently described bacterial family named after Midichloria mitochondrii, the intracellular symbiont of the hard tick Ixodes ricinus (Sassera et al., 2006; Montagna et al., 2013). Midichloriaceae are comparable for variability and phylogenetic complexity to other two families of the order Rickettsiales: Rickettsiaceae and Anaplasmataceae, which include obligate intracellular bacteria causing various and important diseases in humans and other vertebrates (Parola and Raoult, 2001). However, in ecological terms, the family Midichloriaceae is possibly even more complex, since its hosts range from parasitic arthropods (ticks, fleas, bedbugs) to protist (ciliates and also pathogenic amoebae of the genus Acanthamoeba; Vannini et al., 2012; Schulz et al., 2015), also involving marine organisms such as Porifera and Cnidaria (Montagna et al., 2013). The association of Midichloriaceae with parasitic hosts suggests that bacteria of this family could be infectious to vertebrates and could be responsible for some medical and veterinary diseases. Direct and indirect evidence for the transmission of M. mitochondrii to humans and other mammals after the I. ricinus bite were indeed recently published: detection of M. mitochondrii DNA in vertebrate hosts and positivity in serological analysis using sera of parasitized humans and animals (Mariconti et al. 2012, Bazzocchi et al., 2013). M. mitochondrii, present in the ovary and in the salivary glands of I. ricinus females, might play a primary or secondary role in pathologies deriving from the tick bite. In addition, several lines of evidence suggest that other Midichloriaceae are infectious to vertebrates and that they could be responsible for disorders such as the red mark syndrome/strawberry disease in salmonids (Lloyd et al., 2008; Cafiso et al., 2015). However, the infectivity and pathogenicity of Midichloriaceae for humans/mammals has yet to be demonstrated, even if clinical cases compatible with rickettsiosis or ehrlichiosis in humans/animals parasitized by I. ricinus, but characterized by the absence of antibody titers for known pathogenic rickettsiae, could be re-investigated for the presence of signs of Midichloriaceae infections. In summary, several lines of evidence suggest the possibility that the family of Midichloriaceae could include infectious agents/pathogens for vertebrates.
Settore VET/06 - Parassitologia e Malattie Parassitarie degli Animali
2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/510110
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