2025 – PAGE 317 – INFECTIOUS DISEASES
MUMPS VIRUS
For mumps, look for a PAROTIDITIS associated with a low-grade fever. It is difficult to make a mumps diagnosis if there is no fever to suggest infection, so also look for PANCREATITIS, ORCHITIS, or even MENINGITIS (rare). This is a self-limited disease and requires no treatment.
PEARL: Mumps is the most common etiology of parotiditis. It’s generally BILATERAL > unilateral. This is somewhat intuitive. MUMPS = Systemic illness = Bilateral parotiditis. Isolated parotiditis = obstruction of only one of Stensen’s ducts by a stone, or unilateral infection by Staph, etc.
ZIKA VIRUS
Zika virus is a flavivirus transmitted primarily by Aedes mosquitoes, mostly in tropical and subtropical areas with active outbreaks. Transmission can also occur vertically, sexually, or via blood transfusion. Most cases are asymptomatic, but symptoms can include fever, rash, arthralgia, myalgia, and headache.
Zika infection during pregnancy can lead to congenital Zika syndrome, featuring microcephaly, brain abnormalities, eye defects, and other complications. Adults may develop Guillain-Barré syndrome or other neurological issues. Diagnostics can help differentiate Zika from Dengue fever. No treatment exists.
IMAGE: www.pbrlinks.com/ZIKARASH
SARS (SEVERE ACUTE RESPIRATORY SYNDROME)
SARS (Severe Acute Respiratory Syndrome) is a viral disease caused by a type of coronavirus. It was responsible for several outbreaks worldwide in 2002-2004 but has not occurred since then. Outbreaks were characterized by person-to-person transmission most likely by droplets. As indicated by the “severe” in the name, infected individuals had a high likelihood of severe respiratory disease. The worldwide case-fatality rate was 9.6%. Children and adolescents were relatively unlikely to be affected and tended to have better outcomes. One feature that distinguished SARS from many other respiratory illnesses was the prolonged prodromal phase of 3–7 days with fever and malaise but no URI symptoms. No treatment (antivirals or steroids) were shown to be effective.
PEARL: Low yield, but could show up as a distractor within the answer choices.
PARASITES/PROTOZOA
ENTAMOEBA HISTOLYTICA (AKA AMEBIASIS)
For amebiasis, caused by Entamoeba histolytica, look for a history of travel to the Southwestern U.S. or to a Native American reservation. Patients will have abdominal pain associated with diarrhea, which can be watery, bloody, or mucoid. Patients often have TENESMUS. Obtain an ultrasound to look for liver abscesses. Diagnosis with STOOL PCR is preferred over stool smears. Stool examination for cysts is supportive, but it does not allow for definitive differentiation from several other parasites. Treat with metronidazole for any signs of colitis and liver abscess. If metronidazole is not an option, choose iodoquinol.
PEARL: Tenesmus is the feeling of incomplete stool evacuation. It can be associated with pain, straining, or cramping.
IMAGE: www.pbrlinks.com/AMEBIASIS1
MNEMONIC: Imagine a METRO train filled with AMOEBAS playing TENNIS (TENESMUS).
MNEMONIC IMAGE: www.pbrlinks.com/AMEBIASIS2