Table 2 Characteristics and alternative diagnoses of Rift Valley Fever manifestations

Influenza-like syndrome

2 to 6 days of incubation

50–90% of infected people

–

Prolonged asthenia

Arboviruses, influenza virus, HIV (primary infection)

Rickettsia spp., Coxiella burnetii, Salmonella spp., bacterial sepsis

Malarial parasites

Acute hepatitis

Day 2–21

1–2% of symptomatic cases

High in icteric hepatitis

None

EBV, CMV, HIV, hepatitis viruses A, B, C, D, E, arboviruses (yellow fever, dengue, chikungunya)

Mycoplasma, Leptospirosa spp., Coxiella burnetii, Brucella, Bartonella, Babesia, Pneumococcus, Clostridium perfringens

Malarial parasites

Hemorrhagic fever

Day 2–14 (day 2–4)

1–25% of symptomatic cases

25–65%

None

Hemorrhagic viral fevers, Leptospira spp.

Ocular signs

Day 4–20

0.5–15% of symptomatic cases

–

Reduced or lost vision

Measles, rubella, influenza, CMV, HSV, VZV, West Nile, chikungunya, dengue and various encephalitis viruses

Rickettsia spp., Borrelia burgdorferi, Treponema pallidum

Acute encephalitis

Day 2–10

< 1% of symptomatic cases

50%

Neurologic disorders

Enteroviruses, measles, mumps, rubella, influenza, rabies viruses, arboviruses (West-Nile, dengue, regional encephalitis), HIV

Listeria, Rickettsia, Treponema pallidum, Brucella, Borrelia, Leptospirosa spp., Chlamydia, Mycoplasma, ±bacterial meningitis (meningococcal, pneumococcal)

Plasmodium falciparum, Trypanosoma spp., Toxoplasma gondii, Echinococcus, Cryptococcus, Histoplasma capsulatum

Delayed encephalitis

Day 4– 60

1–5% of symptomatic cases

< 50%

Neurologic disorders