Argentina faces rising dengue epidemic risk as mosquitoes hatch early

Patients with suspected dengue symptoms wait for medical attention at a hospital as dengue cases spike during a major outbreak, in Buenos Aires, Argentina, April 5, 2024. REUTERS/Matias Bagli

Mosquitoes are hatching earlier in Argentina and reaching cooler regions than before, as rising temperatures drive the country's worst outbreak of dengue fever and raise the risk of more regular epidemics of the insect-borne virus, scientists said. 

So far in the 2023/24 season, the South American nation has recorded 232,996 cases of the disease sometime known as "break-bone fever" for the severe muscle and joint pain it can cause, along with high fever, headache, vomiting, and skin rash. 

That's well above the previous all-time high of 130,000, recorded last season, and five times the figure at the same point a year ago, the latest official data showed. Cases usually spike in late summer around March-April, but began far earlier this season. 

"The increase in the number of mosquitoes at the end of spring is getting earlier and earlier," said Sylvia Fischer, a doctor in biological sciences and researcher at the National Council for Scientific and Technical Research (CONICET). 

Scientists are seeing the disease more than before in cooler regions further to Argentina's south, Fischer added. 

"These are all places where a few years ago it could not be found," she said, adding that it reflected a wider regional trend where the season for mosquitoes was being extended by warmer weather in part linked to climate change. 

"If I had to extrapolate, I would say that we have the possibility of having dengue epidemics perhaps every year." 

In Argentina, the outbreak this year has strained hospitals and left shelves empty of insect repellent, with sellers hiking prices when they do have supply. The government has moved to ease imports of mosquito spray to meet demand. 

"I have a lot of patients hospitalized for dengue," said Leda Guzzi, an infectious disease doctor, who added that while most cases were not severe, the huge number of cases could lead to a more deadly outbreak next year as people get re-infected. 

"The disease has spread tremendously and we really think next year is going to be very difficult because there are going to be many second episodes of dengue."