You have been called to the scene of an? 83-year-old woman with a high fever who reports chills and shortness of breath. She is tachypneic and showing signs of pain upon inspiration. You talk with her a bit and she seems confused and unaware of where she? is, who she? is, or who you are. Based on this? presentation, the patient likely? has:

pertussis

croup

pneumonia

tuberculosis

The patient most likely has pneumonia.

The rationale is written below.

Step-by-step explanation

We are presented with an 83-year old woman with high grade fever, chills, shortness of breath, and tachypnea. The chest pain during breathing and the confusion are actually red flag signals for elderly patients in particular. Pneumonia is common in the elderly and clinical manifestations are frequently atypical. Pneumonia should be considered in any older person presenting with falls, confusion, incontinence, worsening comorbidities or a deterioration in functional status. The respiratory rate is the most reliable sign to alert the health provider to the presence of pneumonia. 

Tuberculosis is actually a close choice. Clinical symptoms are mostly constitutional, including malaise, fever, weight loss, sweats, anorexia. If the brain is involved, neurological symptoms may include headache, reduced consciousness and cranial nerve palsies. However, the symptoms are not acute such as in the case above wherein there is fever, chills, shortness of breath and tachypnea.

Croup, also known as laryngotracheobronchitis, is less likely in this case since the infection leads to swelling inside the trachea, which interferes with normal breathing and produces the classic symptoms of "barking" cough, stridor, and a hoarse voice.

This couldn't be pertussis as well sinced it is marked by a severe hacking cough followed by a high-pitched intake of breath that sounds like "whoop."