Your question leads me believe that you know how to write avro messages into a Kafka topic. Once your avro message is in a Kafka topic, you will need to write a Consumer which can retrieve the avro message from the topic. The nature of the message doesn’t really matter in terms of retrieving the message. The Spark Streaming documentation provides an example of how to setup a consumer to retrieve events from Kafka topics. You could expand the example to process the avro message.
https://spark.apache.org/docs/latest/streaming-kafka-0-10-integration.html