Pediatric emergency medicine trisk 2318 2318
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Chagas Disease
Chagas disease, an infection caused by the protozoan parasite T. cruzi, is seen in Mexico and central and South
America. The parasite is transmitted through feces of infected triatomine insects (kissing bugs) after a blood meal.
The global prevalence is 8 to 10 million. The common initial presentation is a painless red nodule known as a
chagoma that develops at the site of initial inoculation. Most develop low-grade fever, generalized
lymphadenopathy, and malaise. Rare acute presentations include myocarditis, hepatosplenomegaly, edema, and
meningoencephalitis. While most cases resolve over 1 to 3 months, in approximately 20% of patients, serious
sequelae such as dilated cardiomyopathy, megaesophagus, and megacolon may occur years to decades after the
initial infection. Cardiac manifestations include pericardial effusion which can lead to tamponade physiology, left
ventricular aneurysms, abnormal diastolic function, contractile anomalies, and characteristic EKG findings (right
bundle branch block, left anterior block, AV block, sinus bradycardia, and ST segment, T- and Q-wave
abnormalities). Mortality is due to ventricular arrhythmias, complete heart block, congestive heart failure, or
emboli. Diagnosis is made via Giemsa staining of blood specimens or by direct wet mount prep. Serologies,
available via the CDC, are used to diagnose chronic Chagas. Treatment is with antitrypanosomal medications such
as benznidazole (for 30 to 90 days) or nifurtimox (for 90 to 120 days). The latter can be obtained from the CDC
under a compassionate use protocol: (404) 718-4745. Expert consultation is strongly recommended. Travelers
should avoid contact with the triatomine bug by utilizing insecticide and bed netting and avoiding habitation in
buildings constructed of mud, palm thatch, or adobe brick. Standard precautions are recommended.
RESPIRATORY TRACT INFECTIONS
The most common respiratory infections in returned travelers will be simple viral infections. However, knowledge
of the region of travel can alert clinicians to either common viruses with different seasonality in other hemispheres
(e.g., influenza virus in the middle of the calendar year in subequatorial nations) or for pathogens more common in
other settings. The latter includes tuberculosis (described earlier in the chapter), some vaccine-preventable diseases
more common in developing nations (e.g., diphtheria), and emerging infections, such as the coronaviruses causing
Severe Acute Respiratory Syndrome (SARS) and Middle Eastern Respiratory Syndrome (MERS), which were first
reported in Asia and the Middle East, respectively.
Coronaviruses (SARS, MERS)
Coronaviruses are common causes of mild upper respiratory tract infections, and are known to cause lower
respiratory tract disease, primarily in young or immunocompromised children. In 2002, SARS caused a febrile
illness associated with ARDS and a mortality rate that exceeded 50% in older adults. Disease severity was milder
in young children. Laboratory findings included leukopenia, elevated LDH, and elevated creatinine kinase. In
2012, MERS was first described in a Saudi Arabian man who died of ARDS. Symptoms include fever, chills,
myalgias, and a minority of patients develop diarrhea. Acute kidney injury and multiorgan failure can be seen.
Treatment is supportive. Contact and droplet precautions should be used.
Diphtheria
Diphtheria, a bacterial infection caused by an exotoxin-producing gram-positive bacillus, Corynebacterium
diphtheriae, remains an important disease in resource-poor countries and has experienced resurgence in recent
years in Russia, Haiti, and other countries. Diphtheria is spread via contact with respiratory secretions (airborne,
droplet, or direct contact) or skin lesions. Infection may lead to an asymptomatic carrier state, respiratory disease,
or cutaneous disease. Faucial (nasopharyngeal) diphtheria is the most common form of the disease and is
characterized by the gradual onset of a moderate fever, malaise, and pharyngitis in 80% with a gray-white
pseudomembrane usually covering one or both tonsils. A characteristic odor is usually present. Extensive
membranous pharyngitis may ensue, causing significant swelling of the tonsils, uvula, anterior neck, and regional
lymph nodes causing a “bull neck” appearance. Stridor can be seen with laryngeal involvement. Fever, if present at
all, usually is low grade. Severe complications are seen in approximately 10% of patients and include myocarditis
with arrhythmias or heart failure, or neuritis of the palatal, bulbar, or skeletal muscles. Baseline EKGs should be
obtained in a patient with suspected diphtheria. Cutaneous diphtheria is now more common than nasopharyngeal
disease in the West, with recent resurgence seen in homeless persons in the United States. Chronic, painless
nonhealing scaly rashes with well-demarcated borders or ulcers with a gray membrane appearance characterize
skin involvement.
