Enterococcus casseliflavus infection in a captive Southern Cassowary (Casuarius casuarius): clinical and post-mortem findings.

An adult 22-year-old, male southern cassowary (Casuarius casuarius) presented for lethargy, dysorexia and soft feces. Clinical findings under chemical immobilization were unremarkable except for heterophilic toxic changes on blood smear, reduced albumin/globulin ratio and potentially elevated liver parameters. The animal was treated for suspected hepatobiliary insufficiency and received supportive treatment with daily subcutaneous fluids and medication and was monitored with a quality-of-life assessment. It was eventually euthanized after further deterioration. Post-mortem examination revealed vegetative valvular endocarditis, bile duct obstruction, cholangiohepatitis and splenitis with intralesional Enterococcus casseliflavus isolated. This is a first documented case of E. casseliflavus infection in a bird with multiorgan involvement.

Fatal Chryseobacterium indologenes infection in a captive red-shanked Douc langur (Pygathrix nemaeus).

We report a case of fatal Chryseobacterium indologenes infection in a captive juvenile red-shanked Douc langur in Singapore Zoo. The animal was treated for suspected melioidosis but died within 48 h. Chryseobacterium indolegenes was isolated from the liver and should be included as a differential for bacterial infections in the tropics.

Management of Entamoeba histolytica in the non-human primates at the Singapore Zoo.

Amebic dysentery caused by Entamoeba histolytica accounts for significant morbidity in the non-human primates (NHP) at the Singapore Zoo. This includes the animals in the collection as well as a sizeable free-roaming wild crab-eating macaque (Macaca fascicularis) population. The disease is of great concern because of its zoonotic potential. Passive surveillance, both ante and post-mortem, of NHP displaying clinical symptoms and active surveillance of NHP assessed to be at a higher risk of infection were carried out via fecal real-time polymerase chain reaction (PCR) testing for 4 years. Treatment of the disease with 25 mg/kg metronidazole BID for 10 days followed by 15 mg/kg paromomycin BID for 7 days achieved good clinical resolution in most cases that tested positive. Three diseased NHP with severe clinical signs of weight loss, lethargy, and diarrhea were anesthetized for veterinary diagnostic investigation. Mesenteric lymphadenopathy was consistently seen on ultrasound examination in these severe cases of entamoebiasis. Two animals eventually died of severe chronic enteritis due to the disease. The eradication of entamoebiasis in the NHP at the Singapore Zoo may be complicated by the maintenance of a disease reservoir in wildlife, but a combination of timely treatment and efforts at maintaining biosecurity can help manage the disease in the collection.

Treatments and outcomes of severe hemorrhagic enteritis in three eastern bongos (Tragelpahus eurycerus isaacii) at the Singapore Zoo.

Three eastern bongos (Tragelaphus eurycerus isaaci) presented acutely with hemorrhagic diarrhea at the Singapore Zoo, thought to be caused by a mouldy batch of hay. Repeated fecal tests were negative of parasites and common gastrointestinal bacteria including salmonella and campylobacter. The diarrhea resolved for all individuals after a week of leaf-only diet. However, 2 individuals developed signs of colic. Both animals were anesthetized for examination including blood tests and imaging studies. The findings were consistent of gastrointestinal ileus and a possible impaction. With intensive treatment involving repeated sedations for fluid therapy administration and treatments for gastrointestinal impaction, one individual eventually made a full recovery, but the other individual died due to septic peritonitis secondary to a rupture in the spiral colon. Persistent supportive therapy may be vital in treating severe gastrointestinal disease in this species.

Fatal Septicemia and Mastitis in Wild Sunda Colugos (Sunda Flying Lemurs; Galeopterus variegates) in Singapore.

Two free-ranging female Sunda colugos (Sunda flying lemur; Galeopterus variegates) were found dead in Singapore in November 2018 and February 2019. Septicemia and mastitis were diagnosed in both animals on postmortem examination. Infectious diseases have not previously been established as a cause of death in wild Sunda colugos.

Detection and characterization of a novel marine birnavirus isolated from Asian seabass in Singapore.

BACKGROUND: Lates calcarifer, known as seabass in Asia and barramundi in Australia, is a widely farmed species internationally and in Southeast Asia and any disease outbreak will have a great economic impact on the aquaculture industry. Through disease investigation of Asian seabass from a coastal fish farm in 2015 in Singapore, a novel birnavirus named Lates calcarifer Birnavirus (LCBV) was detected and we sought to isolate and characterize the virus through molecular and biochemical methods. METHODS: In order to propagate the novel birnavirus LCBV, the virus was inoculated into the Bluegill Fry (BF-2) cell line and similar clinical signs of disease were reproduced in an experimental fish challenge study using the virus isolate. Virus morphology was visualized using transmission electron microscopy (TEM). Biochemical analysis using chloroform and 5-Bromo-2'-deoxyuridine (BUDR) sensitivity assays were employed to characterize the virus. Next-Generation Sequencing (NGS) was also used to obtain the virus genome for genetic and phylogenetic analyses. RESULTS: The LCBV-infected BF-2 cell line showed cytopathic effects such as rounding and granulation of cells, localized cell death and detachment of cells observed at 3 to 5 days' post-infection. The propagated virus, when injected intra-peritoneally into naïve Asian seabass under experimental conditions, induced lesions similar to fish naturally infected with LCBV. Morphology of LCBV, visualized under TEM, revealed icosahedral particles around 50 nm in diameter. Chloroform and BUDR sensitivity assays confirmed the virus to be a non-enveloped RNA virus. Further genome analysis using NGS identified the virus to be a birnavirus with two genome segments. Phylogenetic analyses revealed that LCBV is more closely related to the Blosnavirus genus than to the Aquabirnavirus genus within the Birnaviridae family. CONCLUSIONS: These findings revealed the presence of a novel birnavirus that could be linked to the disease observed in the Asian seabass from the coastal fish farms in Singapore. This calls for more studies on disease transmission and enhanced surveillance programs to be carried out to understand pathogenicity and epidemiology of this novel virus. The gene sequences data obtained from the study can also pave way to the development of PCR-based diagnostic test methods that will enable quick and specific identification of the virus in future disease investigations.

Characterization of Fowlpox virus in chickens and bird-biting mosquitoes: a molecular approach to investigating Avipoxvirus transmission.

Avian pox is a highly contagious avian disease, yet relatively little is known about the epidemiology and transmission of Avipoxviruses. Using a molecular approach, we report evidence for a potential link between birds and field-caught mosquitoes in the transmission of Fowlpox virus (FWPV) in Singapore. Comparison of fpv167 (P4b), fpv126 (VLTF-1), fpv175-176 (A11R-A12L) and fpv140 (H3L) gene sequences revealed close relatedness between FWPV strains obtained from cutaneous lesions of a chicken and four pools of Culex pseudovishnui, Culex spp. (vishnui group) and Coquellitidea crassipes caught in the vicinity of the study site. Chicken-derived viruses characterized during two separate infections two years later were also identical to those detected in the first event, suggesting repeated transmission of closely related FWPV strains in the locality. Since the study location is home to resident and migratory birds, we postulated that wild birds could be the source of FWPV and that bird-biting mosquitoes could act as bridging mechanical vectors. Therefore, we determined whether the FWPV-positive mosquito pools (n=4) were positive for avian DNA using a polymerase chain reaction-sequencing assay. Our findings confirmed the presence of avian host DNA in all mosquito pools, suggesting a role for Cx. pseudovishnui, Culex spp. (vishnui group) and Cq. crassipes mosquitoes in FWPV transmission. Our study exemplifies the utilization of molecular tools to understand transmission networks of pathogens affecting avian populations, which has important implications for the design of effective control measures to minimize disease burden and economic loss.