342 articles
Varicella without complication
Varicella without complication (ICD-11 1E90.0) is uncomplicated chickenpox, primary varicella-zoster virus infection with an itchy vesicular rash of 250–500 lesions crusting over 4–7 days, managed with isolation rather than antivirals.
Venezuelan hemorrhagic fever
Venezuelan hemorrhagic fever (VHF), caused by Guanarito virus (GTOV), a New World arenavirus; rodent-borne disease endemic to western Venezuela since 1989, with thrombocytopenia, leukopenia, hemorrhage, and 23.1% case fatality.
West Nile fever
West Nile fever, the febrile illness from West Nile virus (WNV), a mosquito-borne flavivirus; 80% asymptomatic, under 1% neuroinvasive, no human vaccine; first isolated Uganda 1937, spread to Americas in 1999.
Western equine encephalitis
Western equine encephalitis is a mosquito-borne viral disease of the Americas causing brain inflammation in humans and horses; after decades of decline it reemerged in Argentina and Uruguay in 2023.
White piedra
White piedra is an asymptomatic superficial fungal infection of hair shafts caused by Trichosporon species, mainly T. inkin, forming soft white nodules; treated by shaving plus 2% ketoconazole shampoo, distinguished from black piedra caused by Piedraia hortae.
Withering abalone syndrome
Withering abalone syndrome is a fatal bacterial disease of abalone caused by Candidatus Xenohaliotis californiensis, first seen in California in the mid-1980s and promoted by warm water.
Wound myiasis
Wound myiasis, or traumatic myiasis, is infestation of open wounds or ulcers by dipterous fly larvae, mainly screwworms (Cochliomyia hominivorax, Chrysomya bezziana) and blowflies; treated by larval removal and debridement.
Yaws
Yaws (framboesia, pian) is a chronic childhood treponemal infection caused by Treponema pallidum subspecies pertenue, spread by skin contact, curable with single-dose azithromycin, and targeted for eradication; India is the only certified yaws-free country.
Yellow fever
Yellow fever is a mosquito-borne viral hemorrhagic disease of Africa and South America, spread by Aedes, Haemagogus, and Sabethes mosquitoes. The 17D vaccine (Theiler, 1936) gives lifelong protection with one dose; there is no specific treatment.
Yersinia pseudotuberculosis infection
Yersinia pseudotuberculosis infection (yersiniosis, pseudotuberculosis): zoonotic foodborne gastroenteritis with mesenteric lymphadenitis mimicking appendicitis; caused by the gram-negative ancestor of Yersinia pestis; complications include reactive arthritis and Far East scarlet-like fever.
Yersiniosis enterocolitica
Yersiniosis enterocolitica is the common name for infection with Yersinia enterocolitica, a Gram-negative foodborne bacterium from swine that causes yersiniosis, typically enterocolitis with diarrhea and fever.
Zoster without complications
Zoster without complications (ICD-11 1E91.0) is uncomplicated shingles: reactivated VZV causing a painful single-dermatome vesicular rash that heals in 2 to 4 weeks without eye, nervous-system, disseminated, or postherpetic-neuralgia involvement.