Chile's Health Ministry has issued its first-ever preventive health alert for hantavirus across 13 of the country's 16 administrative regions.

SANTIAGO, Chile, July 30 (UPI) -- Chile's Health Ministry has issued its first-ever preventive health alert for hantavirus across 13 of the country's 16 administrative regions to strengthen the healthcare system's response to the disease's rising fatality rate and the simultaneous presence of other health risks, including dengue, yellow fever and avian influenza.

As of last week, authorities had recorded 46 infections and 18 deaths, representing a fatality rate of 39%. The figures contrast with 2025, when 44 infections and eight deaths were reported, equivalent to an 18% fatality rate.

"Hantavirus causes a disease that is endemic to Chile and is transmitted by the long-tailed pygmy rice rat, which lives in rural and semi-rural areas across most of the country," Deputy Health Minister for Public Health Dr. Alejandra Pizarro said.

She said the ministry is continuously monitoring the virus' behavior and the progression of the disease, emphasizing that it is not currently considered an epidemic.

"We are very concerned and actively addressing the situation because this year the virus' fatality rate has increased," she said.

The health alert will strengthen epidemiological surveillance, speed up resource management, allow the hiring of specialized personnel, reinforce health controls and facilitate the direct procurement of essential supplies.

The Pan American Health Organization has maintained an epidemiological alert since December 2025 because of an increase in hantavirus cases across the Southern Cone.

In May, hantavirus also raised international concern following an outbreak detected aboard the expedition cruise ship MV Hondius, which departed from Ushuaia, Argentina, bound for the Arctic.

Passengers had previously traveled through parts of Argentina and Chile, prompting an international investigation led by the World Health Organization. The outbreak resulted in three deaths.

Although the World Health Organization ruled out the risk of a pandemic, the episode once again drew global attention to hantavirus and the need to strengthen epidemiological surveillance.

María Luz Endeiza, an infectious disease specialist and professor at the University of the Andes School of Medicine, told UPI that declaring a preventive health alert is the right decision because it allows authorities to strengthen disease surveillance.

"Rather than indicating a widespread risk for the entire population, this alert highlights the need to increase prevention in areas where the virus is circulating and to reinforce clinical suspicion among both the public and healthcare teams," she said.

She explained that the increase in cases is the result of a combination of environmental factors and human exposure. The virus is transmitted by the long-tailed pygmy rice rat, which sheds the virus through its saliva, urine and feces, contaminating the environment.

"Environmental conditions can alter food availability and the behavior of these rodents, increasing their presence in certain areas," she said.

She added that although climate change could indirectly influence the disease by altering ecosystems and rodent population dynamics, the increase in cases is generally the result of multiple factors.

Allan Mix, director of the Emergency Medicine Specialty Program at Diego Portales University, agreed, saying that changes in rainfall patterns -- droughts followed by periods of intense rainfall -- alter the flowering cycle of native vegetation, the rodents' main food source.

"More food means a population boom for the virus' natural reservoir. Recreational activities in wilderness areas and the expansion of human settlements into areas that have historically been the rodents' habitat directly increase the risk of exposure," he said.

One of the main challenges posed by hantavirus is that there is no vaccine or specific treatment. In many cases, infected people do not seek medical care until the disease is already at an advanced stage.

Mix said hantavirus is endemic to the Southern Cone, but considered it unlikely that it would spread to other countries.

"The virus does not move from one country to another in the classical epidemiological sense. Person-to-person transmission has been documented only in very rare cases, so it is unlikely to spread to other countries. The Andes Mountains are a natural barrier that restricts the habitat of the rodent," he said.