Earlier this week, health officials in Arizona reported a death due to pneumonia, specifically that Plague – responsible for decimating nearly half of Europe’s population during the 14th century, historically known as the Black Death.
At the same time, the US is grappling with its largest measles outbreak in 20 years, with over 1,300 cases confirmed according to the CDC.
The resurgence of numerous infectious diseases, once thought to be under control, raises important questions: how common is the reappearance of disease?
We consulted Professor Paul Hunter, a medical expert from the Norwich School of Medicine at UEA. He discusses the reasons for this resurgence of diseases, the alarming truth behind their persistence, and what it would take for society to face another catastrophic outbreak akin to the Black Death.
How normal is it for infectious diseases believed to be eradicated to return?
The real question is whether they ever truly disappeared. Many infectious diseases that were once common are still circulating and may resurge with vigor. On a global scale, we typically observe one or two significant outbreaks or reappearances annually.
For many of the classic infectious diseases that seem to be re-emerging, they likely never vanished entirely; rather, their reoccurrences can be more localized. For instance, cholera might flare up in areas that haven’t experienced outbreaks for decades.
Is it feasible to eradicate a disease completely?
In theory, it might be possible to eradicate certain diseases. Initially, I believed polio could be eradicated, but it doesn’t seem likely now. Generally, we don’t anticipate the complete eradication of most infectious diseases. While global control and management of infections is achievable, complete eradication remains nearly impossible.
In the case of polio, the vaccine was highly effective, public health initiatives were strong, and it was relatively easy to diagnose outbreaks swiftly.
Today’s landscape presents unique challenges. Many infectious agents can spread before individuals exhibit any symptoms. As demonstrated during the Covid pandemic, it’s nearly impossible to eradicate a disease when transmission is often undetectable.
Compounding this is the difficulty in managing outbreaks in conflict zones. While a vaccine for Ebola exists, controlling outbreaks in the Democratic Republic of the Congo remains a challenge.
What triggers the return of diseases?
The primary factor is viral evolution. This is evident with the flu virus, which adapts over time. Occasionally, significant evolutionary changes lead to faster-spreading variants known as “escaped mutations,” as observed with various Covid variants.
Another factor is how diseases can be transmitted to humans. Some illnesses, like the plague, persist in nature. The “Silvatic plague” infects rodents, and environmental changes can lead to increased human contact with these animals.
In the US, sporadic plague cases have been noted among hunters or individuals who come close to rodent populations.
A major plague outbreak occurred in Madagascar decades ago, largely driven by environmental degradation that put humans in closer contact with infected rodents.
Climate change is also reshaping the distribution of many infectious diseases, introducing them to areas where they were previously uncommon. For instance, small outbreaks of dengue fever are beginning to appear along the Mediterranean coast, a region typically not associated with this disease due to warming temperatures.
A significant contributor to the resurgence of diseases is the decline in vaccination rates. This is particularly evident with the current measles situation in the UK.
I contracted measles as a child, and most people from my generation did as well. However, younger individuals may never have seen a case, leading to reduced urgency surrounding vaccination. When vaccination rates drop, diseases like measles can re-emerge.
What factors contribute to the resurgence of diseases like the bubonic plague?
In essence, there is little difference between modern and historical bacterial infections. The plague remains as virulent as ever, but due to antibiotics, it can be treated in ways that were not available in the Middle Ages.
While the plague remains a serious threat, proper treatment means that few should die from it today, even if infected.
Societal collapse occurs when these diseases become uncontrollable. This phenomenon has been observed in Madagascar, where conflicts, environmental degradation, and economic downturns led to closer interactions between humans and animals, facilitating disease transmission.
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Which infectious disease poses the greatest risk of resurfacing?
Cholera poses a significant threat in certain regions, particularly in Ukraine and Gaza. While cholera is not currently present in either conflict zone, should it appear, it could spread rapidly and result in devastating fatalities.
Currently, there is a cholera vaccine shortage, partly due to the shift in focus toward Covid vaccine production and pandemic disruptions, as well as the recent uptick in cholera infections.
Typically, there would be ample reserves of cholera vaccines, but stockpiles are now depleted, with any upcoming supply already allocated to high-risk countries.
Perhaps the most dangerous threat is the potential for another major flu pandemic, similar to the Spanish flu of 1918. While Covid primarily affected older individuals, the Spanish flu led to agonizing deaths, with severe pulmonary complications. It could cause higher mortality rates than many other infectious diseases.
Another concern is international travel, as evidenced by Covid. What other risks can come from overseas?
Travel poses significant risks, especially from antibiotic-resistant organisms, which some might consider emerging infectious diseases. These viruses have existed for some time but have now developed resistance to multiple treatment options.
Much of this issue arises from practices such as sex tourism, leading to the spread of drug-resistant sexually transmitted infections.
Medical tourism also contributes to this risk, as individuals traveling for affordable cosmetic or dental procedures might inadvertently foster the spread of these resistant strains.
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About our expert
Professor Paul Hunter specializes in the epidemiology of emerging infectious diseases at the Norwich School of Medicine, University of East Anglia (UEA). His research focuses on diseases influenced by environmental factors and has been published in journals such as PLOS 1, Lancet Public Health, and British Medical Journal (BMJ).
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Source: www.sciencefocus.com
