ABSTRACT
Following the detection of an Ebola-like virus in cynomolgus macaques recently imported into the United States from The Philippines, studies were initiated to document transmission at export facilities located in the latter country. At one export facility, 52.8% of 161 monkeys that died over a 2.5-month period were shown to be infected with this virus using an enzyme-linked immunosorbent assay to detect antigen in liver homogenates. A case fatality rate of 82.4% was documented for the infected monkeys. The initial anti-viral antibody prevalence among the captive macaques at this facility was 25.9% (indirect fluorescent antibody titer greater than or equal to 1:16). Followup documented infection of 24.4% of initially seronegative animals and 8.7% of initially seropositive monkeys. Being held in a gang cage versus a single cage was found to be a significant risk factor for subsequent virus infection, and the presence of IFA antibody was shown to predict protection. This study documents unequivocally for the first time the presence of an Ebola-related filovirus in Asia.
Subject(s)
Disease Outbreaks/veterinary , Ebolavirus/immunology , Hemorrhagic Fevers, Viral/veterinary , Macaca fascicularis , Monkey Diseases/epidemiology , Animals , Antibodies, Viral/blood , Antigens, Viral/analysis , Antigens, Viral/blood , Diarrhea/epidemiology , Diarrhea/veterinary , Ebolavirus/isolation & purification , Enzyme-Linked Immunosorbent Assay , Female , Fluorescent Antibody Technique , Follow-Up Studies , Hemorrhagic Fevers, Viral/epidemiology , Hemorrhagic Fevers, Viral/mortality , Housing, Animal , Liver/microbiology , Male , Monkey Diseases/microbiology , Philippines/epidemiology , Prevalence , Regression Analysis , Respiratory Tract Diseases/epidemiology , Risk FactorsABSTRACT
Diagnosis of rabies in dogs was performed in microplates which had been coated with immunoglobulin G previously sensitized to purified rabies virus antinucleocapsids. Homogenized brain suspensions were incubated in the plates and the specific binding rabies antigen was revealed by the use of the same IgG conjugated with horseradish peroxidase. Samples from the same specimens were subjected to standard rabies diagnostic tests--the direct microscopic examination (DME) or Sellers staining for Negri bodies and the fluorescent antibody test (FAT). FAT was used as the reference test or gold standard because of its proven sensitivity and accuracy. The concordance of FAT with RREID was 98.89% while that with DME was 96.67%. Sensitivity of both DME and RREID compared with FAT in this study was 100% while specificity of RREID versus FAT was 98.46% as compared with 95.38% DME versus FAT. The positive predictive value of RREID versus FAT was 96.15% while that of DME versus FAT was 89.29% although the negative predictive value of both RREID and DME compared with FAT was 100%. In the overall assessment, RREID results were demonstrated to approximate closely those of FAT. It is therefore concluded that RREID can be used in diagnostic laboratories to corroborate DME and where MIT and FAT cannot be done. RREID would also be useful in epidemiological studies where large samples are tested.