Snapshot A 50-year-old healthcare worker presents to the emergency room after a month-long trip to India. He reports having fevers, abdominal pain, and a 5-lb weight loss over the past week. He recalls being bit by multiple types of bugs during his summer month in India. His past medical history includes gonorrheal urethritis. His social history includes having several different male sexual partners over the past year often without protection. On physical exam, there is hepatosplenomegaly. He is treated for a presumed parasitic infection, given his clinical risk factors, and tested for HIV. (Visceral leishmaniasis) Introduction Protozoa single-celled eukaryotes, often parasitic, that feed on organic tissues Infections of Protozoa Central Nervous System Gastrointestinal Visceral Infections Hematologic Infections Sexually Transmitted Diseases Toxoplasma gondii Naegleria fowleri Trypanosoma brucei Acanthamoeba Giardia lamblia Entamoeba histolytica Cryptosporidium Trypanosoma cruzi Leishmania donovani Plasmodium Babesia Trichomonas vaginalis Trypanosoma cruzi Introduction clinical syndrome Chagas disease transmission via triatomine, a type of reduviid bug (“kissing bug”) painless bite that deposits feces demographics South America risk factors poor sanitation tropical areas immunosuppression Presentation acute infection Romaña sign is a characteristic sign unilateral periorbital swelling chagoma on the skin at the site of inoculation chronic infection dilated cardiomyopathy apical atrophy megacolon megaesophagus Imaging chest radiograph cardiomegaly barium swallow or barium enema dilated esophagus dilated megacolon Studies peripheral blood smear trypomastigotes (motile flagellated form) detection of antibodies via serology detection of DNA via polymerase chain reaction (PCR) Treatment benznidazole or nifurtimox first-line Leishmania donovani Introduction clinical syndrome visceral leishmaniasis (also known as kala-azar or black fever) cutaneous leishmaniasis transmission via sandfly bites demographics younger children mostly found in India, Bangladesh, Sudan, Ethiopia, and Brazil risk factors HIV/AIDS prognosis visceral leishmaniasis is fatal without treatment Presentation visceral leishmaniasis (kala-azar) spiking fevers weight loss hepatosplenomegaly abdominal pain cutaneous leishmaniasis skin papules that progress to nodule or ulcer Studies pancytopenia biopsy or needle aspiration of bone marrow or skin lesions macrophages with ingested amastigotes (flagella-lacking form) urine antigen testing Treatment amphotericin B or sodium stibogluconate first-line miltefosine second-line Complications post-kala-azar dermal leishmaniasis chronic skin rash with onset months to years after treatment erythematous or hypopigmented polymorphic lesions throughout the body