The hantavirus outbreak detected after a cruise has once again focused attention on a pathogen with an unusual paradox. It has very low transmission between humans, but high mortality, and researchers do not expect it to change in the current episode.
The warning also comes at a time when the scientific community is observing more factors that favor the emergence of new infections or the return of others already controlled. Climate change, human pressure on natural habitats, global mobility, and intensive antibiotic use appear in the same risk chain.
Enric Ollé places climate change and mobility among the drivers of risk
Enric Ollé, a veterinarian, biochemist, and researcher at the Department of Biochemistry and Biotechnology of the URV, maintains that hantavirus is not currently indicating a leap in its ability to spread between people.
"It is a virus with very low transmissibility between humans but with high mortality. It seems to have no mutation and will surely remain that way, in this outbreak" - Enric Ollé, veterinarian, biochemist, and researcher at the Department of Biochemistry and Biotechnology of the URV
Ollé frames this outbreak within a broader trend. The WHO has already identified factors that will push up the risks of infectious diseases, and among them, it highlights the effect of climate change on vectors such as bedbugs and ticks.
The URV researcher adds that global warming displaces species to areas where they were not previously present. This includes insects such as the mosquito that transmits dengue and zika, which can move towards higher latitudes.
"Climate change influences many disease vectors with transmission capacity. Any insect, such as bedbugs or ticks, by changing climatic conditions, modifies its habitat" - Enric Ollé, veterinarian, biochemist, and researcher at the Department of Biochemistry and Biotechnology of the URV
Furthermore, the URV is promoting the study Next Pandemics seeks drugs for future global pandemics and is paying attention to pathogens such as dengue and zika. The project starts from an idea of prevention rather than reaction to an already declared emergency.
Along with climate, Ollé points to other areas of exposure. The circulation of goods, human occupation of areas previously reserved for wildlife, and deforestation in developing countries multiply contacts between people and animals.
In this context, the researcher recalls that some diseases already eradicated in Spain remain active in other territories. He gives rabies as an example, absent here but not eliminated in Morocco, in a context of constant human mobility.
Javier Capilla links the cruise ship case to entering previously distant ecosystems
Javier Capilla, professor of virology in the area of microbiology and researcher of the Mycology and Environmental Microbiology team at the Faculty of Medicine of the URV, relates the cruise ship episode to increasing exposure to environments where infectious particles circulate.
"We have gained ground on the jungle, and we are more exposed now than before. We have destroyed natural environments. The recent cruise ship case and hantavirus did not surprise me excessively because it is very illustrative: we are increasingly accessing more inhospitable places and entering ecosystems with infectious particles. That is why it will become more and more normal for emerging viruses to cause problems or for contagion episodes to be more frequent" - Javier Capilla, professor of virology and researcher at the Faculty of Medicine of the URV
Capilla positively assesses the protocols applied during the hantavirus crisis. Nevertheless, he warns that it is not necessary to reach an epidemic to assume that these episodes will repeat more frequently.
Another added pressure comes from livestock production. Ollé points out that intensive farming and the use of antibiotics favor more resistant bacteria, capable of colonizing humans and remaining in the body without causing immediate harm.
Enric Ollé summarizes it with a specific effect of prolonged antibiotic use. "The use of antibiotics has made bacteria more resistant and when they colonize humans, even if they are not harming them, they remain longer."