Final answer:
Species differences exist in the chronic effects of flea saliva exposure, with pets often developing Flea Allergic Dermatitis (FAD), while humans may experience various allergic reactions. The nature and severity of these responses can vary widely.
Step-by-step explanation:
There are indeed species differences in the chronic effects of flea saliva exposure. When pets like dogs and cats are exposed to flea saliva repeatedly, they can develop a condition called Flea Allergic Dermatitis (FAD). This is a common allergic skin disease in pets, where even a small amount of flea saliva can lead to an intense allergic reaction characterized by itching, skin inflammation, and lesions. Humans can also exhibit allergic reactions to flea bites, although not commonly presenting as FAD. Instead, the reactions could range from mild irritation to more severe allergic manifestations similar to those seen in other Type I Hypersensitivities, such as allergies to dust mites, pollen, or food. Other types of immune responses, like contact dermatitis due to latex exposure or delayed hypersensitivity to substances like poison ivy or tuberculin, differ from the immediate reaction seen in FAD because they involve a different immune pathway and timeline of response.