Association of West Nile Virus with Lymphohistiocytic Proliferative Cutaneous Lesions in American Alligators (Alligator mississippiensis) Detected by RT-PCR

Abstract

West Nile virus (WNV) is known to affect captive populations of alligators and, in some instances, cause significant mortalities. Alligators have been shown to amplify the virus, serve as a reservoir host, and even represent a source of infection for humans. This study describes a cutaneous manifestation of WNV in captive-reared American alligators (Alligator mississippiensis), previously described as lymphohistiocytic proliferative syndrome of alligators (LPSA), based on the findings of gross examination, histopathologic evaluation, WNV antibody testing, and WNV reverse transcriptase polymerase chain reaction (RT-PCR). Forty alligators with LPSA and 41 controls were examined. There was a significant difference (P = 0.01(-21)) in the WNV serostatus between the treatment group (100%) and the control group (0%, 95% CI: 0-7.3%). In the treatment group, 97.5% (39/40) (95% CI: 92.7-102.3%) of the LPSA skin lesions were positive for WNV via RT-PCR. Of the skin sections within the treatment group that had no LPSA lesions, 7.5% (3/40) (95% CI: 0-15.7%) were positive for WNV. In the control group, all of the skin samples were negative for WNV (41/41) (0%; 95% CI: 0-7.3%). The LPSA skin lesions were significantly more likely to be WNV positive by RT-PCR when compared to control animals (P = 0.07(-20)) and normal skin sections from affected animals (P = 0.08(-16)). There was no significant difference in the WNV RT-PCR results between control animals and normal skin sections from affected animals (P = 0.24). These findings suggest that LPSA is a cutaneous manifestation of WNV in alligators.

Diagnostic investigation of new disease syndromes in farmed Australian saltwater crocodiles (Crocodylus porosus) reveals associations with herpesviral infection

“…In American alligators, proliferative lymphohistiocytic cutaneous lesions have been associated with West Nile virus infection. 26 In addition to the LNS cases, there were 4 cases in the nonsyndrome control cases that had erosive and/or ulcerative skin lesions. Although a detailed description of these cases was beyond the scope of this study, they bear mention because herpesvirus was detected in skin from all cases.…”

Viruses Infecting Reptiles

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Applications of Different Weighting Schemes to Improve Pathway-Based Analysis

“…The associations of these new identified significant pathways to the cancer-related disease are also reported in several papers [39, 40, 40]. The names, ranks, and P values of those pathways under absT scheme are compared to those under uniform weight in Table 6.…”