Dermatology MCQ - Viral Infections - Ebola Haemorrhagic Fever

A 32-year-old aid worker returns from the Democratic Republic of the Congo with a sudden onset of high fever, severe headache, myalgia, and fatigue. On day 3, he develops vomiting, diarrhea, and a maculopapular rash. By day 5, he has evidence of mucosal bleeding and petechiae. Laboratory studies show leukopenia, thrombocytopenia, and elevated transaminases. Which of the following is the most likely causative agent and its natural reservoir?

A) Lassa virus; multimammate rat
B) Ebola virus; fruit bats
C) Crimean-Congo hemorrhagic fever virus; ticks
D) Marburg virus; African fruit bats
E) Dengue virus; mosquitoes

Correct Answer: B) Ebola virus; fruit bats

Explanation

This presentation is classic for Ebola virus disease (EVD), a severe and often fatal hemorrhagic fever.

Key Clinical Features of Ebola Virus Disease:

• Initial Phase (Days 1-3): Sudden onset of high fever, severe headache, myalgia, and fatigue.

• Gastrointestinal Phase (Days 3-5): Vomiting, diarrhea, abdominal pain.

• Hemorrhagic Phase (Days 5-7): Mucosal bleeding, petechiae, ecchymoses, and sometimes internal bleeding.

• Rash: A maculopapular rash can appear around day 5, often overlooked in dark-skinned patients.

• Laboratory Findings: Leukopenia, thrombocytopenia, elevated transaminases (AST > ALT), and coagulopathy.

Virologic Features:

• Causative Agent: Ebola virus (species Zaire ebolavirus is most common and virulent).

• Natural Reservoir: Fruit bats (particularly species of the genera Hypsignathus monstrosus, Epomops franqueti, and Myonycteris torquata) are the presumed natural hosts. Humans are infected through contact with bat secretions or through intermediate hosts (e.g., primates, forest antelope).

• Transmission: Human-to-human transmission occurs via direct contact with bodily fluids (blood, vomit, feces) of infected individuals.

Why Not the Other Options?

• (A) Lassa virus: Causes Lassa fever (fever, petechiae, retrosternal pain) but is endemic to West Africa (not DRC). Reservoir is the multimammate rat (Mastomys natalensis).

• (C) Crimean-Congo hemorrhagic fever virus: Causes hemorrhagic fever with similar symptoms but is transmitted by ticks (especially Hyalomma species) and found in wider regions (Africa, Balkans, Middle East, Asia).

• (D) Marburg virus: Causes a disease clinically indistinguishable from EVD (Marburg virus disease). However, the natural reservoir for Marburg is also African fruit bats (especially Rousettus aegyptiacus). While this is a possible answer, the question specifies the Democratic Republic of the Congo, which is a classic region for Ebola outbreaks (e.g., 2018-2020 Kivu outbreak). Marburg is less common in DRC.

• (E) Dengue virus: Causes dengue fever (fever, rash, myalgia) but rarely causes significant hemorrhage or petechiae except in severe dengue ( DSS), and it is transmitted by mosquitoes (Aedes aegypti). It is not associated with bat reservoirs.

Management:

• Supportive care: Aggressive fluid resuscitation, electrolyte management, and symptomatic treatment.

• Isolation: Strict infection control measures (PPE, isolation units) to prevent nosocomial spread.

• Specific therapies: Monoclonal antibodies (e.g., Inmazeb, Ebanga) are approved for Ebola virus disease.

Prognosis:
Case fatality rate for Ebola Zaire is ~50-90% without treatment. Early supportive care and specific therapies improve survival.

Note: Both Ebola and Marburg viruses are filoviruses and cause clinically similar diseases. Geographic context (Ebola in DRC vs. Marburg in Uganda/Angola) and specific virologic testing are needed for definitive diagnosis.