Choosing malaria chemoprophylaxis when the patient is pregnant and the itinerary hits a resistance border. Featuring Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale. Interactive infectious d...

Invasive pneumococcal disease as the first clue to an acquired immunodeficiency. Featuring Streptococcus pneumoniae. Interactive infectious diseases case from IDHub.

A lung transplant recipient's rising CMV viral load despite ganciclovir leads through resistance genotyping, foscarnet toxicity, and ultimately to maribavir. Featuring Cytomegalovirus, CMV. Interactiv...

A veterinary technician with steak tartare, two cats, and three weeks of fever and posterior cervical lymphadenopathy. Featuring Toxoplasma gondii. Interactive infectious diseases case from IDHub.

A leukemia patient with cleared candidemia on micafungin develops meningitis with a negative cryptococcal antigen — and a sanctuary-site drug failure. Featuring Candida tropicalis, Candida. Interactiv...

Progressive foot drop and hand weakness in an immigrant with no skin lesions — and a diagnosis hiding in the nerves. Featuring Mycobacterium leprae. Interactive infectious diseases case from IDHub.

Edmond Nocard was a French veterinarian at Pasteur's institute when he isolated a branching filament from a dying cow in 1888. The genus that bears his name turned out to live in soil worldwide, cause...

Diffuse lymphadenopathy, a hyperinflammatory state, and plasmablasts in an HIV-positive patient with an enhancing retroperitoneal mass. Featuring Human herpesvirus 8, HHV-8, KSHV. Interactive infectio...

Three organisms, three kingdoms, and three antibiotic mechanisms of action tested in a single case of polymicrobial bacteremia from bowel perforation. Featuring Escherichia coli, Enterococcus faecium,...

In 1964, Anthony Epstein, Yvonne Barr, and Bert Achong found the first human cancer virus — after a fog-diverted flight accidentally solved the cell culture problem that had stalled them for years.

An Amazon traveler returns with a dengue-like illness and a vector most clinicians do not think to ask about. Featuring Oropouche virus. Interactive infectious diseases case from IDHub.

A safari traveler returns with fever, regional nodes, and multiple eschars on the legs. Featuring Rickettsia africae. Interactive infectious diseases case from IDHub.

Culture-negative endocarditis, chronic arthralgias, and PAS-positive macrophages on valve tissue. Featuring Tropheryma whipplei. Interactive infectious diseases case from IDHub.

Subacute endocarditis caused by Streptococcus gallolyticus subsp. gallolyticus leading to discovery of colorectal neoplasia — the strongest organism-disease association in clinical infectious diseases...

Fusarium means 'spindle' in Latin, named for the canoe-shaped spores of a soil fungus that destroyed the banana industry in Panama and reshaped the political economy of Central America.

Necrotizing fasciitis with hemorrhagic bullae in a fisherman with hemochromatosis after a minor saltwater laceration — curved gram-negative rods and septic shock within 48 hours. Featuring Vibrio vuln...

Pinta means 'painted' in Spanish. It is the name of a skin disease caused by Treponema carateum, a spirochete indistinguishable from syphilis under a microscope but radically different in what it does...

Eosinophilic appendicitis caused by a nematode with pathognomonic lateral alae, discovered on pathology after appendectomy in a young woman. Featuring Enterobius vermicularis. Interactive infectious d...

Pseudomonas means 'false unit' in Greek and 'verdigris' in Latin. Neither name captures what actually makes this bacterium dangerous: it can eat crude oil. And anything that can eat oil can eat almost...

A gram-positive coccobacillus dismissed as a diphtheroid contaminant in a patient with advanced HIV and a cavitary lung lesion. Featuring Rhodococcus equi. Interactive infectious diseases case from ID...

In 1892, a 22-year-old Argentine medical student saw a round body under his microscope and thought it was a protozoan parasite. He named it Coccidioides — 'resembles Coccidia.' He was wrong about the ...

A previously healthy young man in Texas develops fulminant meningoencephalitis days after swimming in a warm lake, with anosmia and motile trophozoites on CSF wet mount. Featuring Naegleria fowleri. I...

A kidney transplant recipient with recent rejection therapy develops cavitary pulmonary nodules and ring-enhancing brain lesions. Featuring Aspergillus fumigatus. Interactive infectious diseases case ...

Aspergillus is Latin for 'little sprinkler.' The name was coined in 1729 by a Catholic priest who looked at a mold under his microscope and saw the holy water wand he used every morning at Mass.

In 1950, the U.S. Navy sprayed a bright red bacterium over San Francisco to see how a biological weapon would spread through a city. The military thought the microbe was harmless. Eleven people ended ...

A destructive native-valve endocarditis caused by a coagulase-negative staphylococcus that should never be dismissed as a contaminant. Featuring Staphylococcus lugdunensis. Interactive infectious dise...

Most people assume West Nile virus is named after the Nile River. It isn't. It's named after a colonial district in northwestern Uganda — a place most of the world had never heard of until a fever in ...

A 17-year-old with summer encephalitis, temporal PLEDs, hyponatremia, and a negative routine CSF panel. Featuring La Crosse virus. Interactive infectious diseases case from IDHub.

Persistent urethritis in a young man after standard GC/CT treatment, with questions on microbiology, NAAT methodology, and resistance-driven sequential therapy. Featuring Mycoplasma genitalium. Intera...

Hepatitis A, B, C, D, and E sound like a natural sequence — but the alphabetical naming system was an accident of history, not a plan. It started when a British physician replaced misleading names wit...

Severe influenza A after allogeneic HSCT, with questions on viral entry, oseltamivir, and prevention. Featuring Influenza A virus. Interactive infectious diseases case from IDHub.

Before influenza was a virus, it was an astrological event. The word means 'influence of the stars' — a Renaissance belief that outlasted germ theory by 400 years and is still spoken in every clinic d...

A genus feared in CF clinics and listed as a potential bioweapon started with a plant pathologist and a rotting onion in upstate New York. Both the man and the vegetable are still in the name.

Ring-enhancing brain lesions in an HIV patient from Bolivia that fail empiric toxoplasmosis therapy. Featuring Trypanosoma cruzi. Interactive infectious diseases case from IDHub.

In 1905, a pathologist in Panama found a microorganism with a halo, named it for the capsule, and called it a protozoan. Both assumptions were wrong — and both errors are still printed in the name.

A progressive granular nasal ulcer in a Venezuelan coffee farmer. Featuring Paracoccidioides brasiliensis. Interactive infectious diseases case from IDHub.

Before 1973, most severe childhood diarrhea had no visible cause. Then a Melbourne team looked at duodenal tissue from sick children under an electron microscope and found a virus shaped like a wheel.

A hemodialysis patient with MRSA bacteremia who fails to clear blood cultures on vancomycin — and the mechanism behind it. Featuring Staphylococcus aureus, MRSA, VISA. Interactive infectious diseases ...

A rituximab-treated adult in Vietnam with brainstem encephalitis, myoclonus, and a characteristic MRI pattern after contact with hand-foot-and-mouth disease. Featuring Enterovirus A71, EV-A71. Interac...

The HPV vaccine did not need whole virus. Once high-risk HPV was tied to cervical cancer, the crucial trick was getting Saccharomyces cerevisiae to make L1 proteins that self-assembled into virus-like...

A retired gold miner with progressive massive fibrosis develops constitutional symptoms and a new right upper lobe cavitary lesion on CT. Featuring Mycobacterium kansasii. Interactive infectious disea...

Before it became a pathogen board answer, a molecular biology workhorse, and a food-safety headline, Escherichia coli was Theodor Escherich's common colon bacillus in infant studies, and its later nam...

Mycobacterium leprae sounds like clean laboratory Latin, but the second half of the name is far older than bacteriology. Lepra began as a word for rough, scaly skin, and the bacillus that Hansen found...

A man from the Peruvian Amazon develops abrupt fever, painful nodular crops, neuritis, and orchitis several months after completing multidrug therapy for multibacillary leprosy. Featuring Mycobacteriu...

In 1884, Hans Christian Gram was not trying to build a grand bacterial classification system. He was trying to make tiny cocci visible in pneumonic lung tissue, and the method he devised became one of...

A deer hunter from rural Missouri presents with four days of fever, leukopenia, thrombocytopenia, and transaminitis after removing ticks from his legs. Featuring Ehrlichia chaffeensis. Interactive inf...

Before vaccination, Lady Mary Wortley Montagu watched Ottoman smallpox variolation, chose it for her own child, and then pushed the practice into British medicine at a time when the disease still disf...

A humanitarian aid worker presents with cyclical fevers six months after returning from Papua New Guinea despite completing her malaria prophylaxis correctly. Featuring Plasmodium vivax. Interactive i...

In Hammurabi's Babylon, a physician who cut into a dangerous swelling and killed the patient could lose his hands, a sharp reminder of how risky source control was before antisepsis, anesthesia, and a...