What are dengue and malaria caused by?

The infections are different, although both can cause fever, chills and muscle aches. Dengue is spread by certain Aedes mosquitoes; malaria is spread by Anopheles mosquitoes carrying the parasite. A mosquito becomes infected after biting a person or animal carrying the infection, then can pass it on during a later bite. Neither illness is caused by cold weather, ordinary food, or simply being near someone who is unwell. Symptoms can overlap, so the illness cannot be identified reliably from symptoms alone.

Tell a clinician where you have travelled, when you returned, and when symptoms began. A [Blood Test](/treatments/diagnostics-and-screening/blood-test/) may help distinguish malaria, dengue and other causes of fever. Malaria needs prompt assessment because the parasite can worsen quickly. If travel is planned, a [Travel Health Consultation](/treatments/occupational-and-travel-medicine/travel-health-consultation/) can review mosquito precautions and whether [Malaria Prophylaxis](/treatments/occupational-and-travel-medicine/malaria-prophylaxis/) is suitable.

Seek urgent medical assessment for fever after travel to a malaria area, confusion, severe weakness, breathing trouble, repeated vomiting, fainting, bleeding, or inability to drink. A fever with [Chills](/symptoms/chills/) or marked [Muscle Aches](/symptoms/muscle-aches/) also deserves prompt clinical advice, particularly after mosquito exposure. Do not wait for symptoms to become severe before mentioning recent travel.

Ask which infections fit your travel history, whether testing should be repeated, how to manage fever safely, and which warning signs should prompt immediate return.