Peter Chin-Hong has devoted his life to studying a hidden world — and how it can kill you.
He's a professor of medicine and infectious disease specialist at the University of California, San Francisco. Despite his encyclopedic knowledge of things that can make people sick, he said there isn't a lot that scares him.
But there's one big exception: climate change.
"That is something that's scary to me because I feel somewhat out of control," Chin-Hong said.
As human-driven actions change the climate, they're also changing the landscape for infectious diseases. Health officials are grappling with what that means for Hawaiʻi.
"We are way ahead of the game on thinking about planning, infrastructure, resilience and mitigation. But we haven't had health in the forefront of that conversation," said Dr. Diana Felton, the chief of the communicable disease and public health nursing division at Hawaiʻi State Department of Health.
"The truth of the matter is that climate change is going to impact everyone's health," Felton added.
Mosquitos and warmer temperatures
Felton pointed to a couple of ways climate change could impact the spread of disease across the islands. The first has to do with vectors, or living vessels that carry disease and transfer it to humans.
One of the most common vectors is mosquitos. While Hawaiʻi has mosquito populations capable of carrying dengue, Zika and chikungunya viruses, cases of mosquito-borne diseases in humans are relatively low compared to other tropical locations.
If Hawaiʻi's climate grows more hospitable to mosquitos, the islands may see more cases of these diseases. There's also the threat that new species of mosquitoes could be introduced and bring deadly pathogens with them.
"Theoretically, malaria could be possible in Hawaiʻi," Felton said.
Floodwater carrying bacteria
More frequent flooding and sea level rise may also increase the risks of communicable diseases. Floodwaters can carry bacteria like Leptospira, which causes leptospirosis. Rising sea levels may cause cesspools near shorelines to overflow, bringing residents in contact with a whole host of potentially dangerous pathogens.
Felton said that even going for a swim in the ocean may come with greater risks, as pathogens like Vibrio vulnificus, the infamous "flesh-eating" bacteria found in the Ala Wai Canal, become more abundant.
"Vibrio vulnificus really likes warmer water temperatures, so we expect as seawater temperatures increase, we're going to see more cases of Vibrio vulnificus," Felton said.
These changes will take place over time, said Felton, and local health officials are working on how best to prepare. The Department of Health is currently engaged in a vulnerability assessment to ascertain what communities are most at risk.
Crowding and spreading
But one of the more immediate concerns shared by experts like Chin-Hong and Felton is the impact of climate-related disasters on person-to-person transmission of disease.
As climate change makes Hawaiʻi's weather more volatile, people may need to stay inside to escape extreme heat, wildfire smoke or even crowd together in shelters during hurricanes. Those communal, indoor environments can stoke the spread of infectious diseases like COVID-19.
"This is something that we saw a little bit after the Maui fires," Felton said, adding that DOH deployed doctors, nurses and volunteers to provide masks and vaccines to displaced residents in Maui shelters.
Chin-Hong said while there's great work being done on these issues in different corners of the health system, it's time for broader recognition of climate change as a public health crisis.
"I think that there are not enough people who know about infectious diseases as part of this conversation. We really need to step it up," Chin-Hong said.
