Mortality of captive whooping cranes caused by eastern equine encephalitis virus

Of 39 captive whooping cranes (Grus americana), 7 died during a 7-week period (Sept 17 through Nov 4, 1984) at the Patuxent Wildlife Research Center, Laurel, Md. Before their deaths, 4 cranes did not develop clinical signs, whereas the other 3 cranes were lethargic and ataxic, with high aspartate transaminase, gamma-glutamyl transferase, and lactic acid dehydrogenase activities, and high uric acid concentrations. Necropsies indicated that the birds had ascites, intestinal mucosal discoloration, fat depletion, hepatomegaly, splenomegaly, and visceral gout. Microscopically, extensive necrosis and inflammation were seen in many visceral organs; the CNS was not affected. Eastern equine encephalitis (EEE) virus was isolated from specimens of the livers, kidneys, lungs, brains, and intestines of 4 of the 7 birds that died, and EEE virus-neutralizing antibody was detected in 14 (44%) of the 32 surviving birds. Other infectious or toxic agents were not found. Morbidity or mortality was not detected in 240 sandhill cranes (Grus canadensis) interspersed among the whooping cranes; however, 13 of the 32 sandhill cranes evaluated had EEE virus-neutralizing antibody. Of the 41 wild birds evaluated in the area, 3 (4%) had EEE virus-neutralizing antibody. Immature Culiseta melanura (the most probable mosquito vector) were found in scattered foci 5 km from the research center.     

Naturally occurring eastern equine encephalitis in a Hampshire wether.

Eastern equine encephalitis (EEE) was diagnosed (postmortem) in a sheep with clinical signs attributable to a central nervous system disease. The sheep was febrile and initially had front limb incoordination, which progressed to paralysis of both front and hind limbs during a course of 2 days. The sheep maintained an alert attitude with the ability to eat up to the time of euthanasia. The only clinical pathologic abnormalities were neutrophilia and lymphopenia without appreciable leukocytosis, a moderate hyperglycemia, and an elevated creatine kinase. Treatment included hydrotherapy for lowering body temperature, intravenous fluids, thiamine hydrochloride, tetanus antitoxin, antibiotics, and corticosteroids. The only gross lesion at the time of necropsy was a wet glistening surface of the brain (leptomeninges). Microscopically, there was severe nonsuppurative meningoencephalitis, poliomyelitis, and polyradiculoneuritis with mild multifocal neutrophilic infiltration. The EEE virus was isolated from the brain, and subsequent fluorescent antibody testing for EEE was positive on cell culture.     

A survey of helminth parasites in backyard flocks in Michigan by litter examination

The prevalence of parasitic infections in backyard flocks was surveyed using litter samples from 74 pens located on 12 farms in central lower Michigan. Eight species of birds were represented. Two methods of litter examination (a sucrose flotation technique and a multiple washing/ZnCl2 flotation) were compared; the sucrose flotation technique was found to be more useful and was used in the survey. The following parasites eggs/oocysts were observed; ascarid-type eggs (in 34 pens from nine farms), Capillaria eggs (in 30 pens from nine farms), Strongyloides eggs (in nine pens from five farms), Syngamus eggs (in five pens from four farms), and coccidial oocysts (in 40 pens from 10 farms). Contamination of litter with ascarid-type eggs, Capillaria eggs, and coccidial oocysts was commonly found, irrespective of bird species. The contamination level in pens with more than one bird species was lower than in pens with a single species. The relatively high contamination rate may be an indication of the risk of parasitic disease in birds that are not raised under controlled conditions in confinement.     

Detection of eastern equine encephalomyelitis virus antigen in equine brain tissue by enzyme-linked immunosorbent assay

Sensitivity and specificity of an antigen-capture ELISA vs virus isolation in cell culture were evaluated for the detection of eastern equine encephalomyelitis (EEE) virus in the brain tissue of naturally infected equids. Brain specimens from 16 equids with neurologic disease were examined by ELISA and by inoculation onto baby hamster kidney cell cultures. Of 10 brain samples from which virus was isolated in the cell culture bioassay, all were correctly identified as containing EEE virus antigen by ELISA. None of the remaining 6 specimens, without detectable infectious EEE virus, contained detectable antigen. Sensitivity and specificity of the ELISA were 100% with no false-positive or false-negative results. The antigen-capture ELISA was a rapid, sensitive, specific, and simple alternative to a traditional bioassay for the detection of EEE virus.     

抗东方马脑炎病毒结构蛋白E2单克隆抗体的制备及其抗原表位的鉴定

为制备抗东方马脑炎病毒(EEEV)结构蛋白E2的单克隆抗体(MAb)并鉴定其抗原表位,本研究以Bac-to-Bac真核表达系统表达EEEV E2蛋白,纯化后作为免疫原免疫BALB/c小鼠,取其脾淋巴细胞与小鼠骨髓瘤细胞SP2/0进行融合.以原核表达载体pET-30a表达并纯化的EEEV E2蛋白作为包被抗原建立间接ELISA方法筛选杂交瘤细胞,获得4株稳定分泌抗EEEV E2蛋白MAbs的杂交瘤细胞株,分别命名为6F3、6F11、7C11、8B11.Western blot与间接免疫荧光试验结果表明,获得的4株MAbs均与EEEV呈阳性反应,而与西方马脑炎病毒、乙型脑炎病毒以及登革热病毒1型～4型呈阴性反应.利用部分重叠的原核表达的短肽对E2蛋白抗原表位进行鉴定,初步确定MAb 6F11、7C11和8B11识别的抗原表位均为E-33 (321EGLEYTWGNHPPKRVW336),而MAb 6F3无短肽与其反应,推测可能为构象表位.本研究结果为建立EEEV型特异性检测方法、研究E2蛋白结构功能及该病的进一步防制奠定了基础.     

Diagnosis by polymerase chain reaction of Erysipelas septicemia in a flock of ring-necked pheasants

A flock of 810 pheasants experienced 6.2% mortality over 6 days. Affected birds were weak and lethargic for up to 24 hr before death. Examined birds were thin, and gross lesions consisted of thick opaque crops and cecal cores. Histologically, there was capillariasis of the crop and multifocal ulcerative typhlitis with Heterakis spp. infection, and numerous systemic intravascular monocytes were filled with clusters of blue rod-shaped organisms. The organisms were gram-positive bacilli by Brown and Brenn staining and ultrastructural analysis. Liver bacterial cultures were negative for pathogenic bacteria. Erysipelas septicemia was diagnosed by an Erysipelothrix species-specific polymerase chain reaction method with the substrate DNA isolated from formalin-fixed, paraffin-embedded liver.     

Eastern equine encephalitis in 9 South American camelids

BACKGROUND: Eastern equine encephalitis (EEE) virus is a mosquito-borne togavirus (alphavirus) that causes severe (often fatal) encephalitis in many mammalian species, but it has not been reported previously in South American camelids. Hypothesis: South American camelids can become naturally infected with EEE virus and show encephalitic signs similar to those observed in other affected species. ANIMALS: Nine cases (8 alpacas and 1 llama, aged 3.5 weeks to 12 years) were identified; 4 of 9 were 510 weeks old. All cases were from the East Coast of the United States and presented in late summer and fall. METHODS: A retrospective study was performed to include confirmed cases of EEE in camelids in North America before 2006. RESULTS: Eight of nine (89%) camelids died or were euthanized in extremis, with the mean time to death of 2 days. Clinical signs were consistent with encephalitis and included fever, lethargy, ataxia, seizures, recumbency, torticollis, opisthotonus, and vestibular signs. No consistent hematologic abnormalities were identified, and cerebrospinal fluid contained an increased protein concentration in the single camelid analyzed. No successful therapy was identified. EEE was confirmed by alphavirus detection by using immunohistochemistry (IHC) and polymerase chain reaction (PCR) in the central nervous system (CNS) and by serology. Findings included polioencephalitis with lymphocytic perivascular cuffing; neutrophil infiltration; gliosis; neuron satellitosis; necrosis; and edema, with intracytoplasmic alphavirus within neurons and glial cells. No virus was detected in extraneural tissues. CONCLUSIONS AND CLINICAL IMPORTANCE: In endemic areas, EEE should be considered a differential diagnosis for young and adult camelids with CNS disease. Brain histopathology with indirect IHC or PCR is diagnostic.     

Furazolidone-associated cardiomyopathy in two Indiana flocks of ducklings

Furazolidone (FZ)-induced congestive cardiomyopathy was diagnosed as the cause of high mortality and unthriftiness in two flocks of white pekin ducklings. Cumulative mortality at 7 weeks of age was 10.0-14.4%. Samples of FZ-supplemented feeds fed to flocks 1 and 2 from day 1 to day 14 had 140 and 150 mg FZ/kg, respectively. Both flocks had various degrees of water restriction. Clinically, the ducklings had dyspnea, incoordination, and abdominal distention. Necropsy findings included pulmonary edema and congestion, ascites, atrophic congested livers covered with sheets of fibrin, and cardiac enlargement with biventricular dilatation. Cardiac alterations were minimal by light microscopy. Ultrastructurally, scattered myocytes had myofibrillar lysis. These outbreaks occurred following intake of FZ at therapeutic dosages and emphasize the high susceptibility of young ducklings to FZ cardiotoxicity.     

Tunicamycin enhances neuroinvasion and encephalitis in mice infected with Venezuelan equine encephalitis virus

Venezuelan equine encephalitis (VEE) viruses cause natural outbreaks in humans and horses and represent a significant biothreat agent. The effect of tunicamycin on the course of the disease in mice with VEE was investigated, and the combined effects of these agents was characterized. CD-1 mice given 2.5 microg of tunicamycin had >1,000-fold more virus in the brain 48 hours after infection with the virulent VEE strain V3000 and > or =100-fold of the attenuated strain V3034 at all tested times than did untreated mice, indicating enhanced neuroinvasion. Tunicamycin did not alter the viremia profiles of these viruses nor the replication of V3000 in the brain itself. Tunicamycin alone caused ultrastructural blood-brain barrier damage, yet neuroinvasion by V3000 in treated mice appeared to occur via the olfactory system rather than the blood-brain barrier. Tunicamycin-treated, V3000-infected mice also exhibited earlier and more severe weight loss, neurological signs, neuronal infection, neuronal necrosis and apoptosis, and inflammation than untreated, V3000-infected mice. The mean survival time of tunicamycin-treated, V3000-infected mice was 7.3 days versus 9.9 days for untreated, V3000-infected mice. These studies imply that animals that ingest toxins similar to tunicamycin, including the agent of annual ryegrass toxicity in livestock, are conceivably at greater risk from infections by encephalitis viruses and that humans and horses exposed to agents acting similar to tunicamycin may be more susceptible to encephalitis caused by VEE viruses. The exact mechanism of tunicamycin-enhanced neuroinvasion by VEE viruses requires further study.