Malaria is transmitted by mosquito bites, usually between dusk and dawn. The main symptom is high spiking fevers, which may be accompanied by chills, sweats, headache, body aches, weakness, vomiting or diarrhea. Severe cases may involve the central nervous system and lead to seizures, confusion, coma and death.
Taking malaria pills is recommended for travel to rural areas along the borders with Bolivia (lowlands of Salta and Jujuy provinces) and Paraguay (lowlands of Misiones and Corrientes provinces).
Yellow fever is a life-threatening viral infection transmitted by mosquitoes in forested areas. The illness begins with flu-like symptoms, which may include fever, chills, headache, muscle aches, backache, loss of appetite, nausea and vomiting. These symptoms usually subside in a few days, but one person in six enters a second, toxic phase characterized by recurrent fever, vomiting, listlessness, jaundice, kidney failure and hemorrhage, leading to death in up to half of the cases. There is no treatment except for supportive care.
The yellow fever vaccine is recommended for all travelers greater than nine months of age who visit the northeastern forest areas near the border with Brazil and Paraguay.