Emerging Pathogens: A Look Toward 2024

The National Institute of Allergy and Infectious Diseases defines emerging infectious diseases/pathogens as those “that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range.” As the world takes a collective breath after four years of the COVID-19 pandemic caused by SARS-CoV-2 and a global mpox (formerly known as monkeypox) emergency, the ongoing danger from emerging and reemerging pathogens remains very real.

The making of modern-day pandemics

Pandemics create societal disruptions, and there are five consistent, reoccurring themes—1) distrust of government and public health measures, 2) blaming others, 3) fraying of society, 4) conspiracy theories, and 5) rise of the worker. The current and ongoing pandemic is no exception—the modern world has repeated these past patterns and behaviors across its populations.

"The ongoing danger from emerging and reemerging pathogens remains very real."

Today, rapid international travel, ongoing geopolitical disruptions that dissolve borders and result in mass migrations, misinformation and disinformation of public health and healthcare information, climate change and natural disasters (e.g., earthquakes, floods, etc.), and technological advances (e.g., artificial intelligence) all have the potential to compound the ongoing and emerging threat of many pathogens.

Climate-related disasters, such as heat waves, droughts, wildfires, coastal storms, and inland flooding, have the potential to disrupt regional economies, foster health crises like disease outbreaks, and expand the geographical range of vector-borne and neglected tropical diseases.

What will 2024 bring to our shores, our cities, and our homes?

Here is a brief look at possible pathogens—old and new alike:

The respiratory cycle will continue

On December 14, 2023, the Centers for Disease Control and Prevention (CDC) Health Alert Network issued Health Advisory [CDCHAN-00503] for an “Urgent Need to Increase Immunization Coverage for Influenza, COVID-19, and Respiratory Syncytial Virus (RSV) and Use of Authorized/Approved Therapeutics in the Setting of Increased Respiratory Disease Activity During the 2023–2024 Winter Season.”

The world appears to be indifferent as we sleepwalk into a another dangerous respiratory flu/COVID-19/RSV season in the US. In the past four weeks, hospitalizations among all age groups have increased by 200 percent for influenza, 51 percent for COVID-19, and 60 percent for RSV. 

It’s not too late to get your updated vaccinations.

Flu vaccination rates are down a bit from last year. COVID-19 vaccination is severely lagging: more than 60 percent of people over 60 years old are not vaccinated with this year’s monovalent vaccine. And only 16 percent of people over 60 have gotten the RSV vaccine, a new and effective way to prevent hospitalizations.

RNA viruses, like influenza (flu), SARS-CoV-2, and RSV, are notorious for their high rates of mutation, with the ability to “drift and shift” annually, creating a parade of ongoing variants. Flu and SARS-CoV-2 can also “hide” in animal reservoirs like bats, fowl, swine, and other animals.

That said, the 2023–2024 respiratory virus season has already been different, with new or updated vaccines for all three of these pathogens, as well as treatments, such as the game-changing monoclonal antibody treatment nirsevimab (Beyfortus™), which helps protect young children from RSV for up to five months.

The global threat of antimicrobial resistance

The CDC reports that 1 in 31 patients will acquire at least one healthcare-associated infection (HAI) while being treated for something completely unrelated. HAIs include the rapidly growing global problem of antimicrobial resistance (AMR) of all microbial pathogens. In the bigger picture, the World Health Organization (WHO) predicts that by 2050, AMR will result in approximately 10 million deaths annually, surpassing cancer, while the World Bank estimates that AMR will cost an additional USD$1 trillion healthcare dollars globally.

Every few years, the CDC releases its Report on Antibiotic Resistance Threats (2013 and updated in 2019). While there are numerous AMR pathogens from every group of microbes, according to CDC, the current top urgent threats are Clostridioides difficile, Carbapenem-resistant Enterobacteriaceae, drug-resistant Neisseria gonorrhoeae, Candida auris, and carbapenem-resistant Acinetobacter species.

In 2015, the US government released the National Action Plan for Combating Antibiotic-Resistant Bacteria, which was updated in October 2020, building on the framework from 2015 to prioritize infection prevention and control and reduce the need for antibiotic use. The US government also partnered with other nations for the WHO Global action plan on antimicrobial resistance.

"The COVID-19 pandemic has made it clear—prevention is preparedness.”

The alarming geographic expansion of AMR continues to burn like a wildfire across the world. The COVID-19 pandemic disrupted initiatives and efforts to curb AMR, and the US saw a 15 percent increase in resistant hospital-onset infections and deaths during the first year of the pandemic. This was fueled in part by increased prescription of unnecessary antimicrobials, coupled with a lack of AMR tracking and reporting.

Don’t visit the ZOOnosis

Infectious diseases that can be transmitted between animals and humans are called zoonoses. According to the CDC, roughly 60 percent of all known human infectious disease agents originate in animals, including Brucella, HIV, Salmonella, and rabies virus. Most new or emerging infectious diseases in humans are zoonotic in origin (e.g., COVID-19, Ebola, and highly pathogenic avian influenza), with about 80 percent of potential bioterrorism threats being zoonotic (e.g., anthrax and plague). Ultimately, these types of threats require a One Health approach for effective prevention, detection, and response.

The emergence and reemergence of zoonotic agents in 2023 paints a dangerous portrait for 2024 and beyond. The world should continue to be watchful for ongoing outbreaks and expansion of Marburg, Nipah, mpox, Crimean-Congo hemorrhagic fever, and locally-acquired malaria in the US. 

Furthermore, the current explosion of vector-borne (insect vectors) infections continue to expand across the world with diseases like dengue, chikungunya, Rocky Mountain spotted fever, and others.

Current setbacks must be temporary

As the CDC COVID-19: U.S. Impact on Antimicrobial Resistance, Special Report 2022 emphasizes, recent setbacks in combatting AMR and infectious diseases “must be temporary. The COVID-19 pandemic has made it clear—prevention is preparedness.”

As we enter 2024 and beyond, emerging pathogens and infectious diseases and preventing outbreaks must remain top of mind.