Ophidiomycosis surveillance of snakes in Georgia, USA reveals new host species and taxonomic associations with disease

Abstract

Ophidiomycosis (snake fungal disease) is caused by the fungus Ophidiomyces ophiodiicola and threatens snake health worldwide. It has been documented throughout the eastern United States and severe cases have recently been reported in Georgia, USA. To evaluate disease distribution and prevalence in this state, 786 free-ranging snakes were examined for skin lesions consistent with ophidiomycosis and swabbed to detect O. ophiodiicola DNA using qPCR. Sampled snakes represented 34 species and 4 families; 27.5% had skin lesions, 13.3% were positive for O. ophiodiicola DNA, and 77.8% of the qPCR positive individuals had skin lesions. This is the first report of O. ophiodiicola in five of the 22 species that were qPCR positive. Multinomial logistic regression modeling indicated that Drymarchon couperi had a higher relative risk of apparent ophidiomycosis (lesions present and qPCR positive), and the best models predicting qPCR result and ophidiomycosis category included individual factors and excluded temporal and spatial factors. Phylogeny-based bipartite network analysis showed that Nerodia erythrogaster, Nerodia taxispilota, and D. couperi had the highest prevalence of apparent ophidiomycosis; this category was more prevalent in the subfamily Colubrinae and less prevalent in Natricinae. These results provide important information about ophidiomycosis epidemiology, which has implications for snake conservation.

Comparative host-pathogen dynamics of Snake Fungal Disease in sympatric species of water snakes (Nerodia)

“…Consistent with our observations, other studies have shown that Oo prevalence differs intra-generically among Nerodia 44 . In our study, N. h. harteri exhibited higher Oo prevalence compared to N. rhombifer , which is concerning owing to the conservation status and rarity of N. h. harteri .…”

“…Factors that contribute to the probability of Oo infection and mortality among individuals and species vary considerably, although some studies have shown climate and season are associated with incidence and severity of infection 12,17,18,[41][42][43] . However, interspecific 44 and demographic factors 18 associated with pathogen prevalence are still understudied. One study presented evidence of interspecific Oo prevalence differences in Georgia (USA) 44 , and another documented vertical transmission of Oo from infected mothers to neonates among viviparous and oviparous snakes 45 .…”

“…The copyright holder for this preprint this version posted March 9, 2022. ; https://doi.org/10.1101/2022.03.08.483470 doi: bioRxiv preprint demographic factors 18 associated with pathogen prevalence are still understudied. One study presented evidence of interspecific Oo prevalence differences in Georgia (USA) 44 , and another documented vertical transmission of Oo from infected mothers to neonates among viviparous and oviparous snakes 45 . However, there are no published studies assessing the role of interspecific and demographic factors in the distribution of Oo in Texas snake populations.…”

Infection with Nannizziopsis guarroi and Ophidiomyces ophiodiicola in reptiles in Taiwan

“…Snake infections by O. ophiodiicola have been reported in the US, Canada, the UK, Germany, the Czech Republic and Australia (Franklinos et al., 2017; Lorch et al., 2016), and this snake fungal disease (SFD) has been found in more than 30 species of wild and captive individuals belonging to six different families (Haynes et al., 2020; Lorch et al., 2016). The red‐banded snake and Chinese cobra are mainly distributed in Asian countries and are native to Taiwan.…”

Population genetic analysis of Ophidiomyces ophidiicola, the causative agent of snake fungal disease, indicates recent introductions to the USA

“…Hybridization between lineages is also expected to occur more frequently in regions with high Oo prevalence (i.e., more opportunities for co-infections). Thus far, in-depth studies of Oo prevalence in snake communities have been very limited in their geographic scope (e.g., [20,38,39]). Future work would be beneficial to understand the relationship between prevalence and the abundance of hybrid strains.…”