How can ectoparasites transmit diseases in addition to causing skin irritation?

Ectoparasites, such as fleas, lice, mites, and ticks, transmit diseases primarily by acting as vectors for infectious pathogens.1

When these organisms feed on a host, they can facilitate the spread of bacteria and other disease-causing agents in several ways:

• Direct Injection: Many blood-sucking ectoparasites, such as mosquitoes, inject saliva into the host while feeding. If the parasite is carrying a pathogen, it can be introduced directly into the host's bloodstream during this process.2
• Contamination: Some parasites, like the kissing bug, transmit pathogens through their excrement. When deposited on the skin near a bite site, the pathogen can enter the host's body through the bite wound or other breaks in the skin, often aided by the host scratching the area.3
• Pathogen Transfer: By biting an infected host and subsequently biting a healthy one, ectoparasites effectively transport and transmit serious illnesses, including Lyme disease, plague, malaria, and Chagas disease.123