The Nile crocodile of the Okavango Delta in health and disease

Thesis (MSc)-- University of Stellenbosch, 2007.ENGLISH ABSTRACT: Crocodile farming has become an important industry in Southern Africa over the last three decades. The diseases occurring in farmed crocodiles have been well researched, which has contributed to the success of modern crocodile farming operations. However, very little research has been done on diseases in wild crocodiles, and the normal physiology and disease prevalence of wild crocodiles remains largely unknown. In this study Nile crocodiles were captured in the Okavango Delta, Botswana. Blood was collected and normal haematological and blood biochemical ranges were established for a subsample of the population (haematology n=38, biochemistry n=35). The ranges obtained were generally in line with those reported for other species and farmed Nile crocodiles, except for mean haematocrit and total protein, which were relatively low. Parameters were also compared between males and females, as well as between size classes. Females had significantly greater mean red cell cotmt, eosinophils, total protein and potassium than males. Subadults had significantly greater mean haematocrit, haemoglobin, eosinophils, basoph.ils, total protein, globulin, sodium and potassium than yearlings and juveniles. Yearlings had significantly higher blood glucose than juveniles. Cloacal swabs were collected (n=29), which were cultured to establish the normal intestinal flora of these crocodiles. The intestinal flora was found to be diverse, with a mean of 2.7 bacterial species per crocodile. No Salmonella were cultured. Approximately half the crocodiles (48.3 %) also had a fungal component to their intestinal flora. A probiotic was produced based on the normal intestinal flora of the wild crocodiles. The potential for this probiotic to reduce mortalities and improve growth in farmed hatchlings was tested in a controlled experiment. No significant beneficial effect was obtained. A disease survey was carried out on the wild crocodiles by (i) a general clinical examination (n=144), (ii) serological testing for mycoplasmosis (n=30), and (iii) bloodsmear examination for blood parasites (n=38). No clinically apparent sick crocodiles were observed. No antibodies to Mycoplasma crocodyli were detected. The prevalence of hepatozoonosis was 55.3 %. There was no significant difference in the h.aematological parameters of Hepatozooninfected and un-infected crocodiles.AFRIKAANSE OPSOMMING: Oor die afgelope drie dekades het krokodil boerdery in Suiderlike Afrika gegroei tot 'n groat industrie. Baie navorsing is al op die siektes van krokodille onder boerdery omstandighede gedoen, wat tot die sukses van moderne krokodil boerdery bygedra het. Baie min navorsing is al oor die siektes van wilde krokodille gedoen, en die siektes en nonnale fisiologie van wilde Nyl krokodille bly hoofsaaklik onbekend. In hierdie studie was Nyl krokodille in die Okavango Delta, Botswana, gevang. Bloed was getrek en die normale waardes vir 'n sub-seksie van die bevolking se hematolgie (n=38) en bloed biochemie (n=35) was vasgestel. Die waardes was vergelykbaar met die van Nyl krokodille onder boerdery omstandighede, sowel as waardes wat al van ander spesies geraporteer is, behalwe vir gemiddelde hematokrit en totale proteme, wat laag was. Parameters was tussen mannetjies en wyfies sowel as tussen verskillende groottes vergelyk. Wyfies het merkwaardig hoer gemiddelde rooiseltelling, eosinofiele, totale protein, en kalium as ma1metjies gehad. Sub-volwassenes het merkwaardig hoer gemiddelde hematokrit, hemoglobin, eosinofiele, basofiele, totale protern, globulien, natrium en kalium as jaar-oud en jong krokodille gehad. Jaar-oud krokodille het merkwaardige hoer bloed glukose as jong krokodille gehad. Kloak deppers was versamel (n=29), en kwekings gedoen om die normale dermkanaal flora vas te stel. Daar was 'n bree spektrum van dermkanaal flora, met 'n gemiddeld van 2. 7 bakterie spesies per krokodil. Geen Salmonella was gei"soleer nie. Daar was een of meer ftmgi van 48 .3 %van die deppers geYsloeer. 'n Probiotikum was gemaak, gebaseer op die normale dermkanaal flora van die wilde krokodille. Die vermoe van die probiotikum om sterftes te verminder, en groei te verbeter, was op klein krokodile onder intensiewe omstandighede getoets. Daar was geen voordeel daarin gevind. 'n Siekte opname was op wilde krokodille gedoen deur (i) 'n algemene kliniese ondersoek (n=l44), (ii) serologiese toetse vir mikoplasmose (n=30), en (iii) bloedsmeer ondersoek vir bloedparasite (n=38). Geen ooglopend siek krokodille was tydens bemonstering gevind, en daar is geen teenliggame teen Mycoplasma crocodyli gevind. Die voorkoms van Hepatozoon pettiti was 55.3 %. Daar was geen betekenisvolle verskil tussen die hematologie van die Hepatozoon-besmette en nie-besmette krokodille nie

The use of an inactivated vaccine in farmed Nile Crocodiles (Crocodylus Niloticus) for the control of Mycoplasma Crocodyli infection

Since the first report of Mycoplasma-associated polyarthritis in farmed Nile crocodiles in 1995, the disease has spread across Zimbabwe and South Africa and has resulted in significant economic losses on infected farms. Due to poor response to antimicrobial treatment and frequent relapses, the use of an autogenous vaccine to manage disease outbreaks was evaluated. Two previous trials had been performed with a similar vaccine and the results suggested that the vaccine could be effective in alleviating disease, although the numbers of animals were limited in both. This trial aimed to evaluate an inactivated, alum-adjuvanted M. crocodyli whole-cell vaccine in a large group of yearling crocodiles under field conditions on a farm in Zimbabwe where repeated M. crocodyli outbreaks have been reported. The safety of the vaccine was assessed by administrating the vaccine intraperitoneally to a subset of crocodiles. No adverse clinical reactions were observed in any of these crocodiles. A group of two thousand two hundred crocodiles received two intramuscular vaccinations four weeks apart in the autumn of 2011, while another group of two thousand two hundred crocodiles served as unvaccinated controls. Serum was collected from a subset of the vaccinated and unvaccinated crocodiles at different time-points before and after vaccination to evaluate the humoral response to vaccination. Latex slide agglutination tests (LAT) were performed on all samples and positive samples were titrated with the latex slide agglutination test and metabolism inhibition assay. A low percentage of sera were positive with serological tests done prior to vaccination, suggesting either circulating Mycoplasma or maternal immunity. Statistically significant increase in sero-positivity was detected with LAT four weeks after primary vaccination, although the titre remained low. Six weeks after the booster vaccination the percentage seropositive vaccinated crocodiles had decreased and there were no statistically significant difference between the percentage seropositive vaccinated and unvaccinated crocodiles. A significant outbreak of Mycoplasma-like polyarthritis was encountered 6 months after vaccination, in October 2011. Both vaccinated and unvaccinated crocodiles were affected. Serum samples from different subsets of crocodiles were collected and evaluated similar to the vaccine trial. The results indicated that a similar rate of sero-positivity was present in all crocodiles, irrespective of vaccination- or disease status Sera collected during this trial was used to evaluate the performance of the latex slide agglutination assay compared to the metabolism inhibition assay (“Gold standard” assay), as the performance of the LAT had not been evaluated previously. The calculated diagnostic sensitivity was 72%, diagnostic specificity was 32%, the predictive value of the positive test was 36% while the predictive value of the negative test was 69%. This trial indicated that the autogenous, inactivated, alum-adjuvanted, whole-cell vaccine against M. crocodyli was not able to protect farmed Nile crocodiles on an infected farm against clinical Mycoplasma-associated polyarthritis. It was also found that the latex slide agglutination assay could be useful as a robust, pen-side assay to evaluate exposure to M. crocodyli, although other assays, such as PCR, bacterial culture or growth inhibition assays, has to be performed to confirm the presence of disease.Dissertation (MSc)--University of Pretoria, 2012.Veterinary Tropical Diseasesunrestricte

Lymphohistiocytic Proliferative Syndrome of Alligators (Alligator mississippiensis): a cutaneous manifestation of West Nile virus

ABSTRACT In 1999, there were reports of a new type of lesion in the hides of captive reared alligators from Florida. Similar lesions were first reported from alligator hides in Louisiana in 2001; however, it wasn’t until 2002 that small epizootics became apparent. In 2002, the Louisiana Department of Wildlife and Fisheries began a collaborative effort with the Louisiana State University School of Veterinary Medicine (LSU SVM) to help elucidate the etiology of “PIX” disease, later renamed Lymphohistiocytic Proliferative Syndrome of Alligators (LPSA). Preliminary work concluded that LPSA was a systemic disease affecting multiple tissues. Based on the results of this preliminary study, particularly the histopathologic evaluation of LPSA tissues, a viral etiology was established as the top differential for LPSA. Further work revealed that LPSA positive alligators were 476 (95% CI: 79.6, 2845.2) times more likely to be seropositive for WNV than LPSA negative alligators. At that point it was also becoming clear that the occurrence of LPSA matched the occurrence of WNV in alligator farms. Another project was performed to further elucidate the association between WNV and LPSA based on results of WNV serology, WNV RT-PCR, and histopathologic evaluation of animals with (treatment) and without (control) LPSA lesions. Results from this study revealed that in the treatment group, 97.5% (95%CI: 92.7-102.3 %) of the LPSA skin lesions (TxA) were positive for WNV via RT-PCR. Of the skins within the treatment group that had no LPSA lesions (TxB), 8% (95%CI: 0-16.9%) were positive for WNV. In the control group, all of the skin samples (CxS) were negative for WNV. All alligators in TxA were significantly (p=0.07-20) more likely to have RT-PCR WNV positive skin than those in CxS, and TxB (p=0.08-16). There was no significant difference in the recovery of WNV from the skins of alligators from TxB and CxS (p=0.24). The results of this work support the theory that LPSA is a cutaneous manifestation of chronic WNV exposure/infection in captive reared alligators. Therefore the epidemiology of LPSA follows the epidemiology of WNV and prevention, surveillance and control methods used for WNV should effectively decrease the occurrence of LPSA

呼吸器症状を示すフトアゴヒゲトカゲの病原体解析に関する研究

岐阜大学(Gifu University)博士(獣医学)博士論文 (Doctoral dissertation)doctoral thesi

Global Changes in Mycoplasma gallisepticum Phase-variable Lipoprotein (vlhA) Gene Expression in the Natural Host

Mycoplasma gallisepticum is the primary etiologic agent of chronic respiratory disease (CRD) in poultry, a disease largely affecting the respiratory tract of poultry, and causing significant economic losses world-wide. Proteins of the variable lipoprotein and hemagglutinin (vlhA) gene family are thought to be important for host interaction, pathogenesis and immune evasion, but the exact role and mechanisms are not well understood. To better understand the phase variation of vlhA genes, we have conducted large scale, next generation sequencing analysis of M. gallisepticum sampled directly from the tracheal mucosa of experimentally infected chickens and those recovered and passaged in-vitro. In the first study, M. gallisepticum was recovered from the tracheal mucosa over a seven day infection. Of note, the data indicated that, at given time points, specific vlhAs were similarly dominant in multiple independent hosts, suggesting a non-stochastic temporal progression of dominant vlhA expression. Additionally we found that vlhA expression was not dependent on the presence of 12 GAA repeats, suggesting a previously unrecognized mechanism may be responsible, at least in part, for vlhA expression. In the second study, we report the vlhA profile of M. gallisepticum recovered from the trachea of experimentally infected chickens when the input culture expressed an alternate dominant vlhA. Here we report that even when the culture is dominantly expressing vlhA 2.02, there is an immediate shift at one day post infection to the dominant expression of vlhA 3.03, suggesting the expression of this gene many be essential in the earliest stages of the infection process

Role of Mycoplasma gallisepticum and Host Airway Epithelial Cell Interaction in Inflammation

Mycoplasma gallisepticum infection in chickens is associated with severe inflammation of the trachea, air sacs and lungs. M. gallisepticum cytadheres to the tracheal epithelium and mediates infiltration of macrophages, heterophils and lymphocytes to the tracheal submucosa but the molecular mechanisms underpinning the severe inflammatory response is not well understood. This research focuses on identifying how M. galisepticum and chicken tracheal epithelial cell (TEC) interaction might contribute to this response. The first study identified that M. gallisepticum lipid associated membrane proteins (LAMP) from both virulent and non-virulent strains were able to up-regulate several inflammatory genes from tracheal epithelial cells both in vitro and ex vivo including, but not limited to IL-1β, IL-6, IL-8, IL-12p40, CCL-20 and NOS-2. However live virulent strains were significantly more efficient in not only up-regulating these genes to a greater extent but also differentially regulating several unique genes in TECs. The study also identified that M. gallisepticum LAMPs mediate the inflammatory gene up-regulation via TLR-2 ligation in an NF-κB dependent pathway. The second study identified, that interaction of a virulent strain with TECs leads to significantly more macrophage chemotaxis than a non-virulent strain. Macrophages upon co-culture with M. gallisepticum exposed TECs up-regulated expression of IL-1β, IL-6, IL-8, MIP-1β, CXCL-13, CCL-20 and RANTES. Interaction of Rlow ­with TECs enabled more efficient gene up-regulation from macrophages compared to Rhigh. Kinetic analysis of these genes identified the peak of expression of cytokine genes to be 6 hours reducing significantly thereafter, whereas expression of chemokine genes remained significantly above control level until 24 hours. These results further our understanding of molecular mechanisms leading to the severe inflammatory response observed during M. gallisepticum infection and suggest that interaction of M. gallisepticum with chicken tracheal epithelial cells play significant role in this process

A comparison of methods used to measure the in vitro antimicrobial susceptibilities of Mycoplasma species of animal origin

Antimicrobials are commonly used to treat mycoplasmosis in animals. In spite of this and the fact that antimicrobial resistance has been recorded for this group of bacteria there are no universally accepted in vitro means of testing for this resistance, nor is resistance testing for mycoplasmas a routine in most veterinary laboratories. So prior to testing for resistance to a number of mycoplasmas isolated from animals in South Africa it was necessary to compare different tests including broth and agar microdilution tests to find out which one would perform best. Using the field strains M. bovis, M. crocodyli, M. felis, M. gallisepticum and M. synoviae, and the reference strains M. gallisepticum 56USDA, M. gallisepticum VaxSafe MG vaccine strain, M. mycoides T1/44 vaccine strain, and M. mycoides Ygoat (11706) broth- and agar-microdilution minimum inhibitory concentration (MIC)tests were performed using either modified Hayflicks or Mycoplasma synoviae media. Two different metabolism indicator systems were compared in the broth microdilution test (BrMIC) namely sugar fermentation (glucose or pyruvate) with phenol red (SFS) and evidence of reduction with resazurin (AlamurBlue®). It was also tested whether amoxicillin and clavulanic acid (ACA) could be used in the tests to reduce problems associated with contamination. Statistical analyses of the tests (repeatability and linear association) indicated that the BrMIC with SFS was the most reproducible method (pooled standard deviation = 0.14). The antimicrobial ACA was found to not to affect the MIC values (R2= 0.976 to 0.996). Furthermore one hundred forty two field strains including 93 M. bovis, 5 M. synoviae, 21 M. gallisepticum, 13 M. bovirhinis, 8 M. crocodyli and 6 M. felis were tested using the BrMIC+SFS with ACA method. Generally the mycoplasmas originating from poultry were resistant to commonly used antimicrobials and had higher MIC50 and MIC90 values than isolates originating from cattle, crocodiles and cats. It was found that most of the mycoplasmas were susceptible to doxycycline (tetracycline) and enrofloxacin with the exception of M. gallisepticum where 17.9% of strains were resistant to both. Resistance to tiamulin (100%) and tylosin (20 to 64%) was high for the poultry mycoplasmas. Most field isolates tested were resistant to erythromycin, nalidixic acid, florfenicol, norfloxacin, neomycin, sulphamethoxazole, trimethoprim and sulphamethoxazole/ trimethoprim combination, mostly resistant to norfloxacin and florfenicol. It is concluded that BrMIC+SFS with ACA method is a reproducible method that reduces any problems with bacterial contamination. As observed with the poultry strains, it is quite clear that antimicrobial resistance is developing to commonly used antimicrobials such as tylosin, the related pleuromutilins, fluoroquinolones and tetracyclines. In species where antimicrobial therapy is applied routinely such as poultry and possibly feedlot cattle, it is recommended that MIC testing is done prior to any therapeutic interventions.Dissertation (MSc)--University of Pretoria, 2010.Veterinary Tropical Diseasesunrestricte

Investigating the epidemiology of adenoviruses in free-ranging turtles in Illinois

Adenoviruses (AdV) were first reported as a disease threat in chelonians during a mortality event in 2007 caused by a Siadenovirus later named Sulawesi tortoise adenovirus (STADV). Adenoviruses of another lineage, Testadenovirus, have been detected in multiple managed and free-ranging turtles in North America and Europe with variable or unknown relationships to clinical disease. This leaves a large gap in understanding the prevalence and impact of AdV in many turtle species. Therefore, a multi-species investigation to detect novel or existing adenoviruses in Blanding’s turtles (Emydoidea blandingii), painted turtles (Chrysemys picta) and red-eared sliders (Trachemys scripta elegans) using conventional PCR across four counties in Illinois from 2016-2022 was performed. Ten AdV were identified across the three species, with STADV being the most common virus species detected. Subsequently, a highly sensitive and specific TaqMan quantitative PCR assay targeting the DNA polymerase gene of STADV was developed. The newly developed and validated qPCR assay was used to test oral cloacal samples from Blanding’s turtles, painted turtles and red-eared sliders sampled across three Illinois counties from 2017-2022. The prevalence of STADV was 2.4% for Blanding’s turtle samples (n=14), 14.9% for painted turtle samples (n=24), and 45.1% for red-eared slider samples (n=37). Clinical signs associated with STADV detection included quiet, alert, responsive (QAR) mentation (p=0.002), pink mucous membranes (p<0.001), carapacial abnormalities (p=0.036), and plastron abnormalities (p=0.003). These results provide a baseline for the presence and diversity of AdV in free-ranging turtles in Illinois, including evidence that freshwater emydid turtles, such as red-eared sliders or painted turtles, may be the North American reservoir for STADV.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2024-09-16 without embargo termsThe student, Zachary Ready, accepted the attached license on 2024-03-06 at 16:55.The student, Zachary Ready, submitted this Thesis for approval on 2024-03-06 at 17:03.This Thesis was approved for publication on 2024-03-25 at 15:16.DSpace SAF Submission Ingestion Package generated from Vireo submission #20246 on 2024-09-16 at 00:33:2

Investigating the epidemiology of adenoviruses in free-ranging turtles in Illinois

Adenoviruses (AdV) were first reported as a disease threat in chelonians during a mortality event in 2007 caused by a Siadenovirus later named Sulawesi tortoise adenovirus (STADV). Adenoviruses of another lineage, Testadenovirus, have been detected in multiple managed and free-ranging turtles in North America and Europe with variable or unknown relationships to clinical disease. This leaves a large gap in understanding the prevalence and impact of AdV in many turtle species. Therefore, a multi-species investigation to detect novel or existing adenoviruses in Blanding’s turtles (Emydoidea blandingii), painted turtles (Chrysemys picta) and red-eared sliders (Trachemys scripta elegans) using conventional PCR across four counties in Illinois from 2016-2022 was performed. Ten AdV were identified across the three species, with STADV being the most common virus species detected. Subsequently, a highly sensitive and specific TaqMan quantitative PCR assay targeting the DNA polymerase gene of STADV was developed. The newly developed and validated qPCR assay was used to test oral cloacal samples from Blanding’s turtles, painted turtles and red-eared sliders sampled across three Illinois counties from 2017-2022. The prevalence of STADV was 2.4% for Blanding’s turtle samples (n=14), 14.9% for painted turtle samples (n=24), and 45.1% for red-eared slider samples (n=37). Clinical signs associated with STADV detection included quiet, alert, responsive (QAR) mentation (p=0.002), pink mucous membranes (p<0.001), carapacial abnormalities (p=0.036), and plastron abnormalities (p=0.003). These results provide a baseline for the presence and diversity of AdV in free-ranging turtles in Illinois, including evidence that freshwater emydid turtles, such as red-eared sliders or painted turtles, may be the North American reservoir for STADV.Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2024-09-16 without embargo termsThe student, Zachary Ready, accepted the attached license on 2024-03-06 at 16:55.The student, Zachary Ready, submitted this Thesis for approval on 2024-03-06 at 17:03.This Thesis was approved for publication on 2024-03-25 at 15:16.DSpace SAF Submission Ingestion Package generated from Vireo submission #20246 on 2024-09-16 at 00:33:2