2025 – PAGE 312 – INFECTIOUS DISEASES

COXSACKIE VIRUS & ENTEROVIRUS

Coxsackie virus is a subtype of the Enterovirus family, and BOTH can cause HAND, FOOT, AND MOUTH disease. Look for a fever, sore throat, and a maculopapular and vesicular rash on the palms and soles. Also look for small white lesions at the posterior oropharynx or ulcers on the tongue. Some patients ONLY have oral lesions. The skin lesions can be VERY tender. Self-limited. Can give steroids for severe pain.

• PEARL: If present, the oral lesions actually appear FIRST! Maybe it should be called MOUTH, HAND, AND FOOT DISEASE!
• IMAGE: www.pbrlinks.com/COXSACKIEVIRUS1
• IMAGE: www.pbrlinks.com/COXSACKIEVIRUS2
• IMAGE: www.pbrlinks.com/COXSACKIEVIRUS3
• MNEMONIC: MOUTH, HAND, AND FOOT DISEASE! Imagine the hands and feet being fine until the kid sticks them in his INFECTIOUS MOUTH!
• COXSACKIE VIRUS: Coxsackie virus also causes HERPANGINA. Look for high fever and oral lesions in the oropharynx.
  • PEARL: It may be difficult to distinguish between the two Coxsackie syndromes. Keep in mind that herpangina has NO associated skin lesions and may be associated with a HIGH fever and possibly a headache.
• ENTEROVIRUS: A different enterovirus serotype can cause high fevers, a rash, and even “aseptic” or “viral” meningitis. Look for it in the SUMMERTIME.

ADENOVIRUS

Adenoviruses can cause pharyngitis, URIs, conjunctivitis, otitis, and gastroenteritis (diarrhea, nausea, vomiting). Usually no rash; often occurs in the SUMMER.

PEARL: Pharyngitis can be exudative and look like Strep. If you’re presented with a patient who has flu-like symptoms (or conjunctivitis, or a pharyngitis) and then gets GI symptoms, this could be your diagnosis! H1N1 can do that too, but you probably will not see that on the boards. If you do, look for very high fevers.

ARBOVIRUS ENCEPHALITIS

The encephalitic clinical picture (confusion, lethargy) of arbovirus encephalitis will likely be tied to a mention of mosquitoes (California, St. Louis). Diagnose by getting virus-specific “acute and convalescent” antibody titers. That means you draw titers now and then again later to compare. PCR is NOT available.

PEARL: This is probably the ONLY condition on the exam where “acute and convalescent” titers is the correct answer.

MNEMONIC: Imagine sitting under a TREE (ARBO) that grows NOW & LATER candies, which are falling on your HEAD and causing ENCEPHALITIS.

MNEMONIC: (image) www.pbrlinks.com/ARBOVIRUS1

RESPIRATORY SYNCYTIAL VIRUS (RSV)

The chest X-ray of RESPIRATORY SYNCYTIAL VIRUS (RSV) BRONCHIOLITIS will show HYPER­IN­FLATED LUNGS and DIFFUSE infiltrates. Diagnose with PCR or direct immunofluorescence testing on naso­pha­ryn­geal aspirates. Routine use of albuterol should be avoided as the wheezing is related to mucous plugging of the bronchioles and not bronchoconstriction caused by asthma in most cases. Nebulized hypertonic saline can be used in patients that are hospitalized but is not recommended for the emergency room setting. Avoid the use of racemic epinephrine, systemic steroids, chest physiotherapy, and continuous oxygen monitoring in patients hospitalized for RSV. Patients frequently need hospitalization due to the severity of symptoms, comorbidities, and possibly their social situation (family reliability).

• SEVERE BRONCHIOLITIS: Refers to pO2 <65 or pCO2 >40 on ABG, respiratory rate >70 or pulse oximetry with saturations <90%. This is associated with future asthma in about half of patients.
• PEARL: Regarding the causes of bronchiolitis, RSV is first, rhinovirus is second and influenza is 3rd. Other causes include adenovirus, parainfluenza, human metapneumovirus.