Vector Type
Vector Species Name
Ixodes pacificus
Vector Common Name
Western blacklegged tick
Transmitted Diseases

Vector Information

Western blacklegged ticks are found along the Pacific coast, particularly in northern California. These ticks are able to transmit diseases to humans and are very similar in appearance to the Ixodes scapularis. These ticks transmit anaplasmosis and Lyme disease to humans. The normal hosts for these ticks are lizards and other small animals, resulting in low rates of human infections. The adult females and nymphs are the most common stages to bite humans. Western blacklegged ticks have a similar appearance to Ixodes scapularis. They are approximately 3mm in length, adult females have black legs, head and scutum. The abdomen is reddish. The nymphs are colored in a similar manner, but are about half the size of the adults. These ticks can be found in deciduous forests, high brush, and open grasslands. They are present year-round.

Found In

*Disease transmission varies locally. This map depicts where vectors can be found geographically and provides information about diseases these vectors might carry. Vectors might be present in a state or locality, however, and not be carriers of any particular disease. In addition, identified vectors may have a presence in a state, but may not be found throughout that state.