Chlamydia pneumoniae Polioencephalomyelitis and Ganglionitis in Captive Houston Toads (Anaxyrus houstonensis)

Abstract

Chlamydia pneumoniae is a ubiquitous pathogen causing disease in humans, mammals, birds, reptiles, and amphibians. Since 2012, C. pneumoniae infection has caused neurologic disease and mortality in a breeding colony of endangered Houston toads ( Anaxyrus houstonensis) at the Houston Zoo. The purpose of this report is to present the histopathologic and ultrastructural characteristics of C. pneumoniae infection in Houston toads. Fourteen cases were evaluated by histopathology and 1 case was evaluated by electron microscopy. The major histopathologic finding was necrotizing and histiocytic polioencephalomyelitis and ganglionitis. Bacteria formed intracytoplasmic inclusions within neurons but frequently extended into the surrounding tissue from necrotic cells. Ultrastructural evaluation showed the bacteria formed reticulate and elementary bodies characteristic of Chlamydia spp.

Chronic wasting associated with Chlamydia pneumoniae in three ex situ breeding facilities for tropical frogs

“…The majority of cases involves the major amphibian order of frogs (Anura), but salamanders (Urodela) are also susceptible (Martel et al 2012;Mutschmann 1998), whereas evidence in the order of caecilians (Gymnophiona) is still missing. Besides several acute mass mortality events with systemic infections, localised and chronic forms with involvement of central nervous system or lungs have been described (Berger et al 1999;Blumer et al 2007;Fratzke et al 2019). Some amphibian species were found to be asymptomatically infected with chlamydiae.…”

“…Staub and colleagues found their reptilian isolates of C. serpentis and C. poikilothermis being temperature-sensitive and in vitro susceptible to tetracycline and moxifloxacin, but intermediate to resistant to azithromycin (Staub et al 2018). Likewise, treatment was unsuccessful or associated with long-term neurologic deficits so that depopulation of tanks housing infected animals was used to control the disease (Fratzke et al 2019). Rüegg et al (2015) report treatment of seven snakes with chlamydiosis for up to 35 days with a daily intramuscular injection of marbofloxacin and could show on the one hand successful treatment confirmed by negative PCR, but on the other hand one loss and one therapy-resistant snake suggesting general need for implementation of safer and more efficient treatment protocols.…”

“…Clinical signs included ataxia, anisocoria, and decreased righting reflex. Necrotising and histiocytic polioencephalomyelitis and ganglionitis were the major pathological findings and chlamydial inclusions were found within and in the surrounding of neurons (Fratzke et al 2019). In addition, infections with members of the Parachlamydiaceae (genera Parachlamydia Bates et al 2018;Vajana et al 2019 and Neochlamydia Vajana et al In the present study, we have compiled clinical data on chlamydial infections in amphibians from the literature with those from own actual cases.…”

“…A complete overview of cases of amphibian chlamydioses from the literature is depicted in Table 1. Later, C. pneumoniae has been identified as causative agent of disease in amphibians (Berger et al 1999;Bodetti et al 2002;Fratzke et al 2019;Reed et al 2000) and confirmed by molecular methods (Berger et al 1999). An Australian giant barred frog (Mixophyes iteratus) suffering from a severe, chronic, mononuclear pneumonia, non-regenerative anaemia and pancytopenia represents the first chlamydiosis case from the wild.…”

“…Lastly, a retrospective case study from Switzerland had found other chlamydial species besides C. pneumoniae that were closely related to C. suis and C. abortus in a number of paraffin embedded tissue samples from native as well as exotic amphibians (Blumer et al 2007). Another case series describes an exclusively neurotropic form of fatal C. pneumoniae infections in a breeding colony of endangered Houston toads (Anaxyrus houstonensis) in a zoological collection (Fratzke et al 2019). Clinical signs included ataxia, anisocoria, and decreased righting reflex.…”