Herpetic Whitlow

Herpetic whitlow is infection of the distal finger or thumb with herpes simplex virus, either HSV-1 (more common in children, often from autoinoculation with oral HSV, or in healthcare workers from occupational exposure to oral or genital secretions before universal glove use became standard practice) or HSV-2 (more common in adults, typically from autoinoculation from genital lesions).

A prodrome of tingling or burning pain in the affected digit precedes the appearance of grouped, clear vesicles on an erythematous base, which may coalesce, and can be mistaken for a bacterial felon or paronychia, an important distinction given the very different management (incision and drainage is harmful in herpetic whitlow, discussed below).

Associated lymphangitic streaking and tender epitrochlear or axillary lymphadenopathy are common.

Systemic symptoms (fever, malaise) may accompany a primary episode.

Lesions typically resolve over 2 to 3 weeks even without treatment, but recurrence from viral latency in the local sensory ganglion is common.

Primarily clinical, based on the characteristic vesicular appearance and prodrome.

Where confirmation is needed, PCR of vesicle fluid is the most sensitive test; viral culture and direct fluorescent antibody testing are alternatives.

Distinguishing from a bacterial felon is essential: herpetic whitlow lesions are typically grouped vesicles rather than a single area of purulent fluctuance, and Tzanck smear (though largely superseded by PCR where available) can show multinucleated giant cells supporting a herpetic cause.

Aciclovir 400 mg PO tds for 7 to 10 days, or valaciclovir 1 g PO bd for 7 to 10 days, most effective if started within 48 hours of symptom onset, particularly for a primary episode; benefit is more modest for recurrent episodes given their typically shorter, self-limiting course
Incision and drainage should be avoided, since this does not shorten the disease course, risks secondary bacterial infection, and can facilitate viral spread or, rarely, herpetic encephalitis via disruption of normal tissue barriers
Keep the lesion covered to reduce autoinoculation risk to other sites (particularly the eye, given the risk of herpetic keratitis) and to reduce transmission to others
Frequent recurrence (more than 4 to 6 episodes per year) may warrant suppressive therapy (aciclovir 400 mg PO bd, or valaciclovir 500 mg PO od, continued long term), following similar principles to suppressive therapy for genital herpes

Referral: dermatology or infectious disease for diagnostic uncertainty or frequent recurrence; occupational health assessment for healthcare workers with occupationally acquired disease.

Rift Valley Fever

Also known as: RVF

Rift Valley fever is a viral hemorrhagic fever caused by a phlebovirus, endemic to parts of sub-Saharan Africa and the Arabian Peninsula, primarily affecting livestock (with associated significant agricultural and economic impact during outbreaks) but capable of causing human infection and, periodically, significant human outbreaks.

Transmission occurs through mosquito bites, or, more commonly in human cases during livestock outbreaks, through direct contact with the blood, body fluids, or tissues of infected animals, which is why abattoir workers, veterinarians, and herders are at particularly elevated risk during epizootic periods.

The large majority of human infections are asymptomatic or cause a mild, self limiting febrile illness, and it is this mild presentation that accounts for most cases, with severe disease occurring in only a small minority.

The typical mild illness presents with fever, headache, myalgia, and malaise, generally resolving within a week without specific treatment.
A small proportion of patients progress to more severe complications, which define the clinically important minority of cases: ocular disease, with retinal lesions that can cause permanent visual impairment, typically becoming apparent one to three weeks after the initial illness; hemorrhagic fever, with jaundice, bleeding manifestations, and hepatic involvement, carrying significant mortality; and encephalitis, presenting with confusion, seizures, or focal neurological deficit, typically occurring somewhat later in the illness course than the hemorrhagic complications.

Diagnosis is confirmed through RT-PCR detection of viral RNA, most sensitive early in the illness during the viremic phase.
Serology (IgM and IgG) supports diagnosis, particularly useful once the acute viremic window has passed, with IgM indicating recent infection.
FBC and LFTs support assessment of severity, particularly relevant in suspected hemorrhagic presentations, where thrombocytopenia and deranged liver function may be present alongside coagulopathy.
A relevant epidemiological context, livestock exposure, residence in or travel to an endemic or outbreak affected area, is an essential part of the diagnostic picture given the non-specific nature of the illness in isolation.

Differentials include other viral hemorrhagic fevers, malaria, and other causes of an acute febrile illness, with the specific epidemiological exposure context helping to narrow this differential considerably.

No specific antiviral treatment is established, and management is entirely supportive.

Mild disease requires only symptomatic treatment: rest, hydration, and antipyretics or analgesics, avoiding NSAIDs and aspirin where a hemorrhagic complication cannot yet be excluded, given the bleeding risk these agents carry.
Severe hemorrhagic disease requires the same principles of supportive care applied to other viral hemorrhagic fevers: careful fluid and electrolyte management, blood product support for significant bleeding or coagulopathy, and close monitoring for progression, generally in a higher level care setting.
Ocular involvement requires ophthalmological assessment and follow up, given the risk of permanent visual impairment from retinal lesions.
Encephalitis is managed supportively, following general principles applicable to viral encephalitis of other causes.
Prevention centers on vector control, personal protective measures against mosquito bites in endemic and outbreak affected areas, and, critically, appropriate protective equipment and precautions for those handling livestock or animal tissues during outbreak periods, alongside livestock vaccination programs (used in animals rather than routinely in humans, given that human vaccines remain primarily investigational or reserved for specific high risk occupational groups in some settings) as part of broader One Health outbreak control efforts.

Referral: infectious disease or tropical medicine input for confirmed or suspected cases, particularly severe presentations; ophthalmology for any suspected ocular involvement; public health notification given the outbreak potential and the need for coordinated human and veterinary public health response.

Herpetic Whitlow

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management