Emerging Trends in Respiratory Infectious Diseases: Stay Vigilant Ahead of Flu Season

Upper respiratory tract infections (upper RTIs), which affect the upper part of the respiratory system, including the nose, throat, sinuses and larynx, are among the most common illnesses worldwide. A recent analysis found that upper RTIs account for 43% of incident cases from all causes in the 2019 Global Burden of Diseases, Injuries and Risk Factors Study, with fatal consequences occurring mostly in the elderly and children under five years old [1]. Historically, most of those deaths are attributable to seasonal influenza which, according to the World Health Organization, sickens around a billion people annually, including three to five million cases of severe illness and 290,000-650,000 respiratory deaths [2].

Given the significant disease burden of upper RTIs, it is critical to stay aware of emerging trends regarding respiratory infections. Understanding these global trends is vital for the early detection of outbreaks and can help guide public health responses and campaigns. It also allows healthcare systems to update patient care management protocols, allocate resources effectively, and develop comprehensive strategies to address threats.

Emerging trends in respiratory infectious diseases

To help you stay vigilant about respiratory infectious diseases, especially during flu season, here are three emerging trends that we are keeping an eye on:

Bordetella pertussis cases are on the rise. The Pan American Health Organization/World Health Organization (PAHO/WHO) issued an epidemiological alert, encouraging member states to strengthen pertussis surveillance activities and maintain constant monitoring of vaccination coverage in children under five years of age [3]. As PAHO/WHO explains, the alert is in response to a decline in vaccination coverage, coupled with an increase in pertussis cases worldwide. Likewise, in the United States, the Centers for Disease Control and Prevention (CDC) is reporting a return to pre-pandemic levels of pertussis, when more than 10,000 cases are typically reported each year. Preliminary data show that more than three times as many cases (4,864) were reported in the United States as of June 24, 2024, compared to the same time in 2023 (1,746). That makes the number of reported cases this year close to what was seen at the same time in 2019, prior to the pandemic [4].
Avian flu detection is ongoing. While the current public health risk is low, public health officials around the world are monitoring avian flu carefully because of the potential for it to become a pandemic. Since April 2024, 14 human cases of avian influenza A(H5) infection have been reported in the United States. Four of these cases were associated with exposure to sick dairy cows and nine were associated with exposure to avian influenza A(H5N1)-infected poultry [5]. In response, Michigan health officials have launched a seroprevalence study among workers exposed to infected cows, aiming to identify asymptomatic H5N1 infections, assess antiviral effectiveness, understand infection dynamics and prepare for a potential outbreak [6]. The CDC has also issued an open call to industry for influenza A(H5) diagnostic test development and validation [7]. In June 2024, WHO reported the first-ever case of a human infection with H5N2, a different strain of avian influenza [8]. For more, see the WHO’s Avian influenza monthly risk assessment summaries.
Role of surveillance and genomic sequencing grows. As the preceding bullet points illustrate, there has been a significant increase in the surveillance and sequencing of respiratory pathogens. This helps in rapidly identifying new variants and understanding transmission patterns, particularly for viruses like seasonal influenza and SARS-CoV-2, which are known to produce variants with different transmission rates, vaccine efficacy and severity of illness. Surveillance methods for respiratory pathogens continue to evolve through advanced molecular techniques, real-time data collection (including wastewater and air sampling) and global collaboration. In addition, advancements such as genomic sequencing, digital health tools and AI-driven analytics are enhancing early detection and tracking to improve outbreak response.

The benefits of monitoring emerging trends in respiratory infectious diseases

From a patient perspective, staying aware of global trends regarding respiratory illness can help individuals make informed decisions about vaccinations, travel, personal hygiene, and other factors that could reduce their risk of infection. From a global health perspective, monitoring emerging trends provides insights into the global spread and mutation of respiratory pathogens. This information is essential for international collaboration and coordinated response efforts to prevent and control outbreaks. Moreover, early identification of circulating strains and associated symptoms can help healthcare providers and public health officials administer timely and appropriate medical interventions, improving patient outcomes and reducing complications.

To learn more about molecular testing for respiratory pathogens, click here.

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