The Vaccine Blog
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The Vaccine Blog
youmevaccines@gmail.com
What are the emerging infectious diseases in 2024?
Epidemics (and certainly pandemics) are “a thief who steals the young and the old and gives no time to mourn.”
This was the description given when Valeria Gawron from New York asked her father about his experience of the 1918 influenza pandemic, caused by the highly infectious virus Influenza H1N1.
He also described how “it stole Joseph, my namesake after he helped his friend pull a wagon up the street. It stole Stanley who had just learned to throw a ball to the other side of the yard.”
Young Valeria queried why her grandfather couldn`t mourn
His response: “We were too busy burying our dead and keeping our families safe. We barely had time for a priest to bless your uncles’ bodies before we put them in the ground. We were so afraid someone else would get sick if we did not bury our dead within hours.”
When her grandfather took her to their graves the following year, she noted that there were no gravestones and asked her grandfather the reasoning behind this.
“We wanted to forget…”
This poignant story reflects an extremely crucial principle - any infectious bacteria or infectious virus, be it pandemic influenza, smallpox, polio, or any of the various others impact many people's lives in many different ways globally. One only needs to cast their mind back to the past few years to appreciate this. However, as with many principles related to this topic, what I discuss here will likely continue to be relevant into the next several years, decades, and possibly even further into the future. With that, in this post I`m going to discuss several important concepts. First, what is the definition of an emerging pathogen? What do we actually mean when we talk about that concept? What are the emerging infectious diseases in 2024? Some also ask - what is the difference between emerging and re-emerging diseases? I`ll discuss what the emerging infectious diseases posing the biggest threats are.Specifically I`ll talk about their case and fatality rates, their pathology (or how the disease develops) and finally how we can promote acceptance of vaccination and other public health interventions for such infectious diseases.
The first question to ask is important for grasping the fundamentals - what is the definition of an emerging pathogen? Further, what is the difference between emerging and re-emerging infectious diseases? The WHO (World Health Organization), and other healthcare authorities such as the Centre for Disease Control and Prevention (CDC) have offered several definitions of emerging infectious diseases. They are defined by both the WHO and also the CDC as “diseases that appear in a population for the first time, or that may have existed previously but are rapidly increasing in incidence or geographic range.” To address the second question - what is the difference between emerging and re-emerging infectious diseases - the name should be a strong indicator as to what the answer is. Although the specifics of the definition can vary among sources, re- emerging infectious diseases can generally be defined as diseases that are recurring after long periods where case rates were declining.This leads to a set of public health issues on a very large scale.
With this speed and scale of transmission, it is crucial to be as prepared as is practically possible. In order to achieve that, we need to ask an important question. What are the re-emerging infectious diseases in 2024, and indeed beyond?
The infectious virus H1N1
With that, what is an example of a re emerging infectious disease? One key example of these you have likely heard news reports about and also on online platforms. Namely, you may have heard about increased cases of the avian influenza virus, caused by the infectious virus A(H5N1),. This name is based on the fact that influenza viruses are subdivided into 4 major types; A, B, C, and D. H5 refers to the type 5 hemagglutinin protein present on the surface of the virus and N1 to the type 1 neuraminidase protein on the same. Subtypes A and B cause seasonal epidemics of disease in humans almost every winter, with influenza A viruses being the only strain known to cause pandemics such as the 1918 Spanish flu pandemic discussed above. With that, it makes sense to state that Influenza A viruses are not novel (new), or even recent. However, cases of avian influenza infection are re-emerging - meaning that they are increasing in incidence and geographic range. In fact, in the decade from 2013 to 14th July 2023, the World Health Organisation has documented 878 cases of H5N1 infection in humans, with 458 (or 52.16%) fatalities across 23 countries Other studies have described H5N1 cases in England, Spain, India and even Lesotho in Southern Africa.
According to the website of the World Health Organisation, symptoms of being infected with this highly pathogenic and infectious virus range from mild to severe. They may include an unusually high fever, (i.e >38 degrees), cough, general malaise, sore throat, and muscle aches. Earlier symptoms may include conjunctivitis, gastrointestinal symptoms, and various other non-respiratory symptoms. This infectious virus can also cause more severe symptoms such as pneumonia and severe systemic sepsis, both of which can be fatal. Fortunately, the majority of patients recover from such symptoms within a week. For H5N1 specifically, the incubation period (that is the time from being infected until symptoms develop) is typically 2 to 5 days on average, but can last up to 17 days. However, as with all disease, some subsets of the population are at increased risk of severe disease, hospitalization and even death from this infectious virus. These include elderly individuals, infants and young children, and those who are immunocompromised.
Measles
Being probably the most infectious virus known to man (or at least, one of the most infectious), it is unsurprising that measles cases are increasing in populations of unvaccinated and undervaccinated individuals. There are many multifaceted and complex reasons for this. However, according to the website of the World Health Organisation, failing to vaccinate and thus reach herd immunity is the key case of these outbreaks. They state that in 2018,close to 10 million cases and over 140,000 deaths were recorded globally from measles. Concerns in scientific and medical circles increased with time, as these case numbers had tripled by November 2019. Further, in 2017, measles caused the deaths of 110,000 people worldwide. These cases occurred mainly in children under the age of 5, and immunocompromised adults.
Measles, or rubeola, symptoms are caused by a highly infectious virus.The incubation period (or the time from when the person initially contracts the virus to when symptoms begin to develop)-can last from 1 to two weeks following contact with the virus. Symptoms presenting can include a fever, a runny nose (rhinitis), bloodshot eyes, and small white spots on the inside of the mouth known as Koplik spots, or Koplik`s sign. These appear between 10 and 12 days after infection The characteristic rash of measles typically develops on the face and neck 14 days following exposure to the infectious virus, as red spots on the skin. It typically spreads over 3 days, eventually to the hands and feet, and fades after 5 to 6 days. Further,more severe complications resulting from infection include subacute sclerosing panencephalitis (SSPE), , blindness, deafness, ear infections, and more severe respiratory symptoms including pneumonia. Patients may also develop complications in the central nervous system, including primary measles encephalitis, acute post-infectious measles encephalomyelitis, measles inclusion body encephalitis, and subacute sclerosing panencephalitis
Mycobacterium Tuberculosis
No list of re-emerging infectious diseases would be complete without at least mentioning tuberculosis disease; caused by infectious bacteria known as Mycobacterium Tuberculosis. One quarter of the world's population are latently infected with tuberculosis, with 10-20% of such cases resulting in secondary tuberculosis disease. According to the website of the World Health Organisation, every year 10 million people contract tuberculosis. Of these, 1.5 million die, making tuberculosis the most common cause of death by infection, surpassing even the death toll of COVID 19. It is also a leading cause of death in HIV-infected individuals, and in 2020, 862,000 incidences of TB occurred among HIV-infected persons globally. In the same year 1.8 million people initiated tuberculosis preventative treatment, a course of one or more anti-tuberculosis medications given to those at risk of developing tuberculosis disease. In 2022 alone, 8,331 tuberculosis cases were reported in the United States, a 5.9% increase in comparison to 2021. Other recent studies have suggested that pregnant women, children, the elderly, and even anaemic patients, are also at significantly increased risk of complications and death from these infectious bacteria compared to the general population.
According to the website of the World Health Organisation, common symptoms of contracting the infectious bacteria include prolonged coughing which may include blood (hemoptysis)/phlegm that lasts for over 2 weeks, chest pain, weakness, fatigue, chills, fever, night sweats,loss of appetite and unexplained weight loss. In exceedingly rare cases, tuberculosis aneurysm of the aorta occurs. This refers to a weakening, “ballooning” and, if left untreated, eventual rupture of a major blood vessel serving blood rich in oxygen to the rest of the body. Beyond the cardiovascular system, the central nervous system (CNS) among others can be affected by several mechanisms following transmission via the blood (bacteremia). In the case of the CNS, this can cause tuberculosis meningitis, the most fatal form of TB reported in approximately 1-5% of patients with tuberculosis disease
Whooping cough (Pertussis)
Pertussis (more commonly known as whooping cough) is a contagious, sometimes life-threatening re-emerging infectious respiratory disease. It is caused by the highly infectious bacteria Bordetella Pertussis. Before the 21st century, pertussis was a major cause of childhood mortality, with over 200,000 cases of the infectious bacteria reported annually. More recently, between 2005 and 2019, there were a total of 33,481 pertussis cases with the average annual incidence rate of 6.4 cases per 100,000 people, with the highest proportion of incidences in infants under one year of age. Further, according to the European Centre for Disease Control and Prevention,”in 2022, 2 623 cases of pertussis were reported by 29 EU/EEA countries. Two countries (Germany and Poland) accounted for 60% of all reported cases”
According to the website of the Centre for Disease Control and Prevention (CDC), pathogenesis (or the development of the disease) may start out similar to the common cold or another mild upper respiratory infection. Initial symptoms of the infectious bacteria include a fever, runny nose (rhinitis),and a cough, typically develop a week to 10 days following infection. However, in pertussis infections, this coughing may last for weeks or even months. In the first week to fortnight, episodes of coughing can become paroxysmal (meaning violent and unpredictable), and may increase in frequency and severity before resolving over a period of several weeks, or longer. Further, a 2020 literature review published by Victoria A. Jenkins and colleagues also found that “immunodeficiency and smoking have also been associated with worsened pertussis symptoms and an increased pertussis-related hospitalization rate. “
Clearly, emerging and re-emerging infectious diseases will continue to pose an ever-increasing set of threats into the next years and decades. Knowing this, the next natural question is, how do we approach prevention and control of re-emerging diseases? Or, at least, can we minimize threats to some degree? Thankfully, the answer to both questions is an overwhelming yes. Regardless of whether it is an infectious virus or infectious bacteria, many similar principles apply to approaching such emerging infectious bacteria and any emerging infectious virus. Such insights are valuable despite the fact that more tailored interventions are needed for certain ethnic groups and other subpopulations. I will focus on vaccine hesitancy mainly, however it is crucial to note that multiple interlinked strategies are needed to even start addressing such severe, global threats.
A 2024 seven-country study investigated strategies to “design interventions aimed at increasing awareness on the complexity of vaccine hesitancy among healthcare professionals involved in discussing childhood vaccines with parents.“ The authors found that including interventions to maximize sharing of social science insights to clinical settings, benefit healthcare practices and education, as well as developing resources relating to vaccine hesitancy, and providing evidence-based knowledge applicable for drafting health policies in many European countries. Other studies have found that presenting accurate information about the infectious virus or infectious bacteria in question in a positive way can favor open and positive attitudes and thus better communication. Further, surveillance and monitoring of any emerging infectious virus and bacteria is a strategy that has been consistently emphasized by many papers and health authorities, including the CDC.
In summary, any emerging infectious virus and/or infectious bacteria will continue to pose significant threats into the future. Reducing incidences, epidemics and pandemics of Avian influenza A H5N1, measles, and infectious bacteria such as tuberculosis and whooping cough, as well as many others will require multi pronged approaches. Research and statements from health authorities advise disease monitoring and surveillance, positive messaging and open communication, and developing accurate and reliable resources around vaccines and vaccine hesitancy. The key theme that can be tracked throughout the literature is trust between the public and health authorities. The mentioned goals are more likely to be achieved and maintained as a by-product of this, rather than through a more impersonal lens. Public health involves people, and that is the key principle I believe we need to keep in mind. Thanks for reading
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