Given the task definition and input, reply with output. In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Which childhood disease starts with a d?, Context: The top three single agent/disease killers are HIV/AIDS, TB and malaria. While the number of deaths due to nearly every disease have decreased, deaths due to HIV/AIDS have increased fourfold. Childhood diseases include pertussis, poliomyelitis, diphtheria, measles and tetanus. Children also make up a large percentage of lower respiratory and diarrheal deaths. In 2012, approximately 3.1 million people have died due to lower respiratory infections, making it the number 4 leading cause of death in the world.
diphtheria