Mpox, Chickenpox, and Smallpox
Understanding the Differences in Transmission, Treatment, and Prevention
As the world continues to respond to the mpox (formerly known as monkeypox) outbreak, it is essential to clarify the differences between mpox, chickenpox, and smallpox—three diseases that share similar names but differ significantly in their causative agents, transmission routes, and implications for public health. The World Health Organization (WHO) has recently updated its understanding and classification of how these pathogens transmit through the air, which is crucial for managing these diseases effectively.
WHO's Updated Understanding of Airborne Transmission
Airborne Transmission: A Unified Framework
The WHO has recently consolidated various terms such as "droplet" and "aerosol" under a unified category of "airborne transmission." This updated terminology reflects a broader understanding that pathogens can transmit through the air under specific conditions, and that these conditions dictate the necessary preventive measures. Here are the key aspects of this new framework:
Airborne Transmission: This term now encompasses all forms of transmission through the air, including both larger respiratory particles (previously referred to as droplets) and smaller particles that can remain suspended in the air for longer periods (formerly referred to as aerosols). This change simplifies the categorization and underscores that the size and behavior of these particles can vary depending on the environment and the activities involved (e.g., speaking, coughing, or medical procedures).
Transmission Routes for Mpox, Chickenpox, and Smallpox
Mpox
Causative Agent: Mpox is caused by the mpox virus, part of the Orthopoxvirus genus.
Transmission Routes:
Direct Contact: The primary transmission mode is through direct contact with lesions, bodily fluids, or contaminated materials such as bedding or clothing used by an infected person.
Airborne Transmission: Mpox can be transmitted through airborne particles, especially in environments where close, prolonged contact occurs, or in healthcare settings during certain medical procedures. This reinforces the need for appropriate ventilation and the use of personal protective equipment (PPE).
Chickenpox (Varicella)
Causative Agent: Chickenpox is caused by the varicella-zoster virus, part of the Herpesviridae family.
Transmission Routes:
Airborne Transmission: Chickenpox is highly contagious and spreads efficiently through airborne particles. These particles can remain in the air and infect individuals even after the infected person has left the room. This makes chickenpox highly contagious, particularly in enclosed spaces like homes or schools.
Direct Contact: The virus can also spread through direct contact with the fluid from chickenpox blisters, increasing the risk of transmission.
Smallpox
Causative Agent: Smallpox was caused by the variola virus, another member of the Orthopoxvirus genus.
Transmission Routes:
Airborne Transmission: Smallpox primarily spread through airborne particles, which could remain infectious over long distances and time, particularly in closed environments. This capability for airborne transmission was a significant factor in the rapid spread of smallpox outbreaks.
Fomite Transmission: Smallpox could also be spread through contact with contaminated objects or surfaces, such as bedding or clothing, making it a significant risk in household and healthcare settings.
Comparison Table
Treatment Options
Mpox:
Antiviral Treatment: Tecovirimat (Tpoxx) is approved for treating mpox. It’s most effective when administered early in the course of the disease.
Supportive Care: Symptom management is critical, including treating fever, pain, and dehydration. Secondary bacterial infections of skin lesions may require antibiotics.
Chickenpox:
Antiviral Treatment: Acyclovir is effective in reducing the severity of chickenpox, especially in adults, pregnant women, and immunocompromised individuals.
Supportive Care: Includes antihistamines for itching, fever reducers, and maintaining hydration.
Smallpox:
Eradicated: No treatment is currently needed as smallpox has been eradicated. Historically, treatment focused on symptom management.
Prevention Measures
Vaccination:
Mpox: Vaccination with JYNNEOS or ACAM2000 is available for high-risk individuals. These vaccines also offer some protection against smallpox due to the similarity between the viruses.
Chickenpox: The varicella vaccine is widely used to prevent chickenpox, usually administered in childhood. A booster (MMRV) may be given as part of routine immunization.
Smallpox: Routine vaccination ceased after eradication. However, smallpox vaccines are still maintained in stockpiles as a precaution against bioterrorism.
Infection Control:
Mpox: Isolation of infected individuals, use of PPE for healthcare workers, and contact tracing are essential to control outbreaks. Public awareness about avoiding contact with wild animals in endemic areas is also critical.
Chickenpox: Infected individuals should be isolated until all lesions have crusted over. Vaccination remains the primary preventive measure.
Smallpox: Not applicable due to eradication, but in historical contexts, strict isolation and quarantine were the primary methods of controlling outbreaks.
Diagnostics
Mpox:
Diagnostic Methods: Polymerase chain reaction (PCR) is the most reliable method for diagnosing mpox, typically using samples from skin lesions.
Clinical Diagnosis: Healthcare providers should consider travel history and exposure to animals or individuals in endemic areas.
Chickenpox:
Diagnostic Methods: Chickenpox is primarily diagnosed based on clinical presentation. PCR and serological tests can confirm the diagnosis in atypical cases or immunocompromised patients.
Clinical Diagnosis: The characteristic vesicular rash and its progression are key diagnostic features.
Smallpox:
Diagnostic Methods: Historical diagnosis relied on clinical features and laboratory confirmation via electron microscopy or viral culture. Since eradication, routine diagnostics are not applicable.
Clinical Diagnosis: In its time, smallpox diagnosis was based on the distinct rash and systemic symptoms.
Information for Healthcare Workers
Mpox:
Early Recognition: Be vigilant for patients presenting with fever and a vesicular or pustular rash, especially if they have a history of travel to endemic areas or contact with known cases.
PPE Use: Strict adherence to PPE protocols, including N95 respirators, is essential to prevent nosocomial transmission.
Vaccination: Healthcare workers at high risk may be offered the mpox vaccine.
Chickenpox:
Vaccination Advocacy: Ensure patients, especially children, are up-to-date with their varicella vaccinations.
Management of Complications: Be prepared to manage severe cases, particularly in immunocompromised patients.
Smallpox:
Knowledge Retention: While eradicated, healthcare workers should maintain an understanding of smallpox for historical knowledge and in the context of bioterrorism preparedness.
Information for the Public
Mpox: Understand that mpox is not the same as chickenpox or smallpox. It is less contagious than chickenpox but more serious than the typical case of chickenpox. Seek medical attention if you have symptoms, especially if you have been in contact with an infected person or animal.
Chickenpox: Ensure you and your children are vaccinated. While usually mild, chickenpox can be serious in adults and immunocompromised individuals.
Smallpox: There is no current risk of smallpox, as the disease was eradicated in 1980. However, vaccines are available in case of exposure due to bioterrorism.
Information for Journalists
Accurate Reporting: Emphasize the differences between mpox, chickenpox, and smallpox in your coverage. Avoid using terms interchangeably as this can lead to public confusion.
Sources: Rely on information from reputable sources such as WHO, CDC, and peer-reviewed medical journals to inform your reporting.
Information for Policymakers
Resource Allocation: Ensure that resources, including vaccines and antiviral treatments, are distributed equitably and that healthcare systems are supported to manage potential surges in cases.
Public Health Messaging: Support clear and consistent public health messaging to prevent misinformation and panic. Promote vaccination programs and preparedness plans.
Global Collaboration: Engage in international cooperation to manage cross-border transmission and share data on emerging cases.
Conclusion
The WHO’s updated understanding of airborne transmission emphasizes the importance of recognizing the specific conditions under which pathogens like mpox, chickenpox, and smallpox can spread through the air. This knowledge is crucial for implementing effective public health strategies, particularly in controlling outbreaks and protecting vulnerable populations. By staying informed and vigilant, healthcare providers, the public, journalists, and policymakers can work together to mitigate the impact of these diseases and prevent future outbreaks.