Disease threat from climate change must be addressed

By The Editorial Board

January 17, 2024 70

PUBLIC health experts are becoming increasingly alarmed at the spread of tropical diseases driven by climate change, both in terms of their appearance in new regions and their increase in occurrences in tropical regions where they are already prevalent. The reports from data collected for 2023 are disturbing and strongly suggest that our own health authorities must take a more proactive approach to identifying and preventing diseases such as dengue fever and infections from bacteria.

The problem is getting the most attention from countries such as the US simply because cases of diseases associated with tropical conditions are beginning to appear in numbers there. In October, two cases of locally transmitted dengue infection were recorded for the first time ever in California; prior to that, all cases of dengue that appeared in the US were in people who had been infected in other countries. There have been numerous cases of infection in the US from the Vibrio vulnificus bacteria, a pathogen that thrives in warm water and is sometimes associated with so-called red tide algal blooms; at least 17 deaths were recorded in 2023, with a couple of those occurring as far north as New York and Connecticut.

There have also been increases in the number of heretofore exceedingly rare tropical infections, such as the nearly always fatal Naegleria fowleri, also known as the "brain-eating amoeba"; coccidioidomycosis, also known as "Valley fever," a fungal respiratory infection; and infections from the lone star tick. The latter is at least one dangerous pest that we do not have to fear here in the Philippines as of now, as it is endemic to warm areas of the southern US and Central America, but we should be cautious about preventing it from arriving here accidentally, such as in cargo shipments; the most common lasting health effect it inflicts on its victims is a lifelong allergy to red meat.

Elsewhere, in South and Southeast Asia, most of Africa, and Central and South America, health authorities have also reported what seems to be a steady rise in the incidence of diseases associated with warmer climate conditions, some of the ones described above as well as other dangerous infections such as malaria. There is also some evidence to suggest that warmer conditions are contributing to a rise in cases of tuberculosis in many tropical countries, including the Philippines.

Researchers have explained that the warming climate is helping diseases thrive and spread to new areas for two main reasons. The first is obvious; most pathogens and their vectors (such as mosquitoes) thrive in warm conditions. The second reason is the changes in patterns of human movement and habits due to hotter conditions. People are simply more likely to expose themselves to diseases, especially waterborne infections, by seeking to keep cool in hot weather or through unintentional means such as being exposed to floodwaters.

Despite their understandable concern, researchers have said that the trend in the increasing numbers and geographical spread of tropical infections is not surprising. Since the problem is being driven by global warming, it is expected to become progressively worse. That is certainly not at all an encouraging outlook, but awareness of the problem does suggest a way in which public health authorities can manage it effectively. However, it will require a substantial shift in the approach to addressing disease incidence, from responding to outbreaks to anticipating them.

Put another way, health officials cannot simply wait for diseases to appear but should apply effort in seeking out the potential infectious agents and the conditions that allow them to thrive. This is already done in some ways, such as the occasional campaigns to educate the public and clean up stagnant bodies of water that can harbor disease-carrying mosquitoes, but these types of initiatives must be expanded and carried out even in the absence of any actual cases of infection.

At the same time, the monitoring and treatment of tropical disease cases should be reviewed and strengthened. The public health system will need to be able to effectively handle the inevitable increase in disease cases, as well as to ensure prompt identification of potential new problem areas that might be revealed by cases of infection, even if there are only one or two victims.