California health officials reported Thursday that the state is on track to break a 55-year record for whooping cough infections in an epidemic that has already claimed the lives of nine infants.
At least 4,017 cases of the highly contagious illness have been reported in California. Data from the Centers for Disease Prevention and Control show 11,466 cases nationwide, though the federal numbers are known to lag behind local reporting.
Whooping cough is a cyclical illness that peaks in number of infections every five years. Symptoms are similar to the common cold, making it a challenge to diagnose, which in turn makes it difficult for officials to determine if the worst has passed, said Dr. Gil Chavez, an epidemiologist for the California Department of Public Health.
A persistent cough that lasts weeks is the tell-tale symptom of the illness, which is also known as pertussis.
The state is on track to exceed the record 4,949 cases reported in 1955.