Traveler's Diarrhea: This is the most common diagnosis for someone returning from a trip to Punta Cana with diarrhea. Traveler's diarrhea is often caused by bacterial pathogens such as Escherichia coli (E. coli), but it can also be viral or parasitic in origin. The symptoms typically start within a week of arrival in a new country and can be attributed to consuming contaminated food or water.

Viral Gastroenteritis: Viruses like norovirus and rotavirus can cause diarrhea and are commonly spread through contaminated food, water, or close contact with infected individuals.
Food Poisoning: Consuming spoiled or contaminated food can lead to food poisoning, which presents with symptoms like diarrhea, vomiting, and abdominal cramps.
Parasitic Infections: Parasites such as Giardia lamblia can cause diarrhea in travelers, especially if they have consumed untreated water or have been exposed to contaminated food.

Cholera: Although less common, cholera is a serious bacterial infection that can cause severe diarrhea and dehydration. It's crucial to consider this diagnosis, especially if the patient has consumed untreated water or undercooked seafood.
Inflammatory Bowel Disease (IBD) Exacerbation: If the patient has a pre-existing condition like Crohn's disease or ulcerative colitis, travel could potentially exacerbate their symptoms.
Intestinal Parasites with Systemic Involvement: Certain parasites can cause systemic infections that are life-threatening if not treated promptly, such as amoebiasis or strongyloidiasis.

Cyclosporiasis: This is a parasitic infection caused by Cyclospora cayetanensis, which can lead to prolonged diarrhea. Outbreaks have been associated with imported produce.
Brainerd Diarrhea: A rare condition characterized by chronic diarrhea with an unknown cause, potentially related to infectious agents.
Microsporidiosis: A rare parasitic infection that can cause diarrhea, particularly in immunocompromised individuals.