A death can be from a virus.Logical formLearned from16 sentences. A strain of a virus may mutate into a form.Logical formLearned from16 sentences. A virus may undergo a monitoring.Logical formLearned from16 sentences. Risk can be for a spread of a virus.Logical formLearned from16 sentences. (Test results) can be for a virus.Logical formLearned from16 sentences. A bird may be infected with a virus.Logical formLearned from16 sentences. A spread may pertain-to a (polio virus).Logical formLearned from16 sentences. Tests may confirm presence of cases of a (bird flu virus).Logical formLearned from16 sentences. A virus may be detected in poultry.Logical formLearned from16 sentences. An outbreak may pertain-to a (polio virus).Logical formLearned from16 sentences. Viruses can be defective.Logical formLearned from16 sentences. Virus can be in birds.Logical formLearned from16 sentences. Contrast can be to viruses.Logical formLearned from16 sentences. Resistance can be to a virus.Logical formLearned from16 sentences. A virus may cause severe illness.Logical formLearned from15 sentences.