CDC Case Challenge: Four People With Cough and Dyspnea After Attending a Baseball Game

Christina A. Nelson, MD, MPH; Katharine M. Cooley, MPH; David W. McCormick, MD, MPH


October 07, 2021

Editorial Collaboration

Medscape &


The patients' presentations of severe dyspnea and hemoptysis after common exposure during a sporting event are most indicative of pneumonic plague caused by intentional release of Yersinia pestis. By the following day, media reports describe dozens of patients with a respiratory illness and hemoptysis in the Cincinnati area. They all had attended the same baseball game between the Pittsburgh Pirates and Cincinnati Reds. Five patients have died and 16 are in intensive care.

Plague is a zoonotic disease caused by Y pestis, a gram-negative coccobacillus transmitted to humans by flea bites, direct contact with infected materials, or inhalation.[1] It is often referred to as the "Black Death" due to high case fatality rates during historic pandemics and dark necrosis of the skin visible among dying patients.[2] Although rare, plague remains endemic in many countries, including the western United States,[3] with approximately 1000 cases occurring globally each year.[4] Recent outbreaks in Madagascar in 2017[5] and the Democratic Republic of the Congo in 2020[6] have demonstrated the continued importance of preparedness for this disease.

In addition to being a naturally occurring threat, Y pestis is a Tier 1 bioterrorism select agent, the highest risk category for threats to public health.[7] The patients described here all reported attending the same baseball game 2 days prior to their presentation, which, since the game was not in an area with known Y pestis endemicity, indicates an intentional release of Y pestis. The World Health Organization (WHO) has estimated that an airborne release of 50 kg of Y pestis bacteria over a city of 5 million people could result in 150,000 cases of pneumonic plague and 36,000 deaths.[8,9]

If multiple patients present with similar respiratory symptoms following a large public gathering, the differential diagnosis can be divided into two broad groups: bioterrorism-related and non–bioterrorism-related.

If a bioterrorism event is suspected, inhalational anthrax and pneumonic tularemia should also be considered because both diseases can have nonspecific symptoms, although fever and cough are prominent. In cases of inhalational anthrax, the classic finding on chest radiography is a widened mediastinum due to hilar adenopathy. This finding is not seen on patient 1's chest radiograph. Pneumonic tularemia is a severe illness but does not typically cause hemoptysis; chest radiography may show patchy infiltrates or pleural effusions.

If a bioterrorism event is not suspected, common diseases to consider are influenza, COVID-19, and community-acquired pneumonia. Since this event took place during the summer months, influenza is not likely, especially given that such a high number of patients who developed severe disease within 2 days of exposure. COVID-19 is a possible diagnosis; however, the lack of other clinical signs of COVID-19 in any of the patients (eg, loss of smell) and the fact that the severity of disease escalated to the point of hospitalization within 2 days makes COVID-19 less likely. Community-acquired pneumonia from a bacterial or viral pathogen is possible; however, the number of severely ill patients in this scenario, including those described by the media, is not consistent with community-acquired pneumonia because large outbreaks are not seen with this disease.

Hantavirus pulmonary syndrome, often caused by Sin Nombre virus, is unlikely since infections typically occur in the western United States among persons who had contact with rodents or nesting material. Additional diagnostic possibilities include leptospirosis, acute pulmonary histoplasmosis, blastomycosis, and coccidiomycosis.