Microbe mystery pt 1

​July 17, 2023

Therapeutic indication

• Beyfortus is indicated for the prevention of RSV lower respiratory tract disease in:

  • Neonates and infants during their first RSV season

  • Children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season

​This patient was infected with Trypanosoma cruzi while on his trip to the Amazon. Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted by the feces of an infected triatomine bug ("kissing bug").

Generally, transmission occurs after a triatomine bug bite is scratched, and the bite is infected with the bug's feces.

An indication that a person may be acutely ill withTrypanosoma cruzi is known as Romaña's sign - swelling of the eyelid caused by introduction of triatomine bug feces into the eye.

It is likely that this patient was exposed to triatomine bugs due to his accommodations while traveling (thatched roof homes) and his inconsistent bed net usage.

If untreated, acute Chagas disease can progress into a "chronic indeterminate" form marked by the absence of blood parasitemia. Individuals progressing to this chronic stage can remain asymptomatic for decades. However, 20-30% of asymptomatic individuals will experience a reactivation of disease and may develop life threatening medical issues, including heart rhythm abnormalities, a dilated heart, a dilated esophagus or a dilated colon. Additionally, immunosuppression can result in a reactivation of disease and parasitemia.

Infection with T. cruzi is diagnosed through preparation of thin and thick blood smears stained with Giemsa stain. Trypomastigotes can be seen on both smear types. On thin smears, the trypomastigotes are "C" shaped with a central nucleus and prominent, subterminal kinetoplast, as in the image above.

Treatment of T. cruzi infection is recommended for all infected individuals. Treatment options include Benznidazole or Nifurtimox.