Final answer:
Considering the presented symptoms and travel history of Peru, the most likely causes of the illness are a bacterial, viral, or protozoan infection. Laboratory tests would be pivotal in pinpointing the specific pathogen to determine the appropriate treatment.
Step-by-step explanation:
The most likely cause of Peru's symptoms would be a bacterial infection, a viral infection, or a protozoan infection. These are all common causes of foodborne illnesses that typically present with gastrointestinal symptoms. Since the patient is experiencing symptoms such as fever and diarrhea, which can be associated with bacterial pathogens like Vibrio cholerae or Campylobacter jejuni, viral pathogens like norovirus, or protozoan infections like Giardia lamblia, it is critical to obtain more information and possibly perform laboratory tests to identify the specific pathogen.
The fact that this condition developed following travel suggests that the patient may have consumed contaminated food or water, which is a common source for these infections. Treatment will depend on the final diagnosis, which may involve antibiotics for bacterial infections, supportive care for viral infections, and specific anti-parasitic treatment for protozoan infections.