The most common organs affected are the lungs and brain. Sick animals may appear thin, have respiratory difficulties due to pneumonia, and/or exhibit abnormal behavior. However, these signs are also present with other types of illness and are not specific to morbillivirus. When exposed to morbillivirus, some animals mount an antibody response, which usually protects against future infections and clinical disease. Other animals may not acquire this protection and can succumb to the disease or to secondary infections that arise as a result of immunosuppression from the infection. Dolphins, porpoises, and whales with clinical morbillivirus infection have exhibited the following symptoms:
- Skin lesions
- Pneumonia
- Brain infections