Welcome to the Rift Valley Fever Outbreak Toolbox

Key reference documents

Case definitions

• Any suspected or probable case with a laboratory positive result (detection of virus by RT-PCR, positive IgM or IgG seroconversion², or virus isolation).

• Any suspected or probable case with a negative laboratory result (showing no specific antibodies, RNA or specific detectable antigens).

Early disease: 

Acute febrile illness (axillary temperature >37.5 ºC or oral temperature of >38.0ºC) of more than 48 hours duration that does not respond to antibiotic or antimalarial therapy, and is associated with:

• Direct contact with sick or dead animals or its products
• Recent travel (during last week) to, or living in an area where, after heavy rains, livestock die or abort, and where RVF virus activity is suspected/confirmed
• Abrupt onset of any one or more of the following: exhaustion, backache, muscle pains, headache (often severe), discomfort when exposed to light, and nausea/vomiting
• Nausea/vomiting, diarrhoea or adnominal pain with one or more of the following: severe pallor (or Hb < 8 gm/dL); low platelets (thrombocytopenia) as evidence by presence of small skin and mucous membrane haemorrhages (petechiae) (or platelet count < 100x109/dL), or evidence of kidney failure (oedema, reduced urine output (or creatinine > 150 mol/L) OR
• Evidence of bleeding into skin, bleeding from puncture wounds, from mucous membranes or nose, from gastrointestinal tract and unnatural bleeding from vagina, OR
• Clinical jaundice (3-fold increase above normal of transaminases).

Late stages of diseases or complications (2-3 weeks after onset): 

Patients who have experienced, in the preceding month a flu-like illness, with clinical criteria, who additionally develop the following:

• CNS manifestations which resemble meningoencephalitis AND/OR:
• Unexplained visual loss, OR:
• Unexplained death following sudden onset of acute flu-like illness with haemorrhage, meningoencephalitis, or visual loss during the preceding month.

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_{1. Early signs and symptoms suggestive of RVF commonly include: suden onset of fever (>38°C) with headache, myalgia and/or arthralgia, and no other identified cause (e.g. malaria), or spontaneous miscarriage without other identified aetiologies.}

_{2. A rise in IgG antibody titers between two consecutive samples taken 2-weeks apart.}

Laboratory confirmation

• Rift Valley Fever: Diagnostic Techniques in OIE Terrestrial Manual page 615 (Paris: World Organisation for Animal Health; 2018).
• Rift Valley Fever Technical Disease Cards in OIE Terrestrial Manual page 4 (Paris: World Organisation for Animal Health; 2018).

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Response tools and resources

• Rift Valley Fever Technical Disease Cards (Paris: World Organisation for Animal Health Terrestrial Manual, 2018).

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Training

•  Rift Valley Fever: Introduction. Open WHO Outbreak channel (Geneva: World Health Organization; 2017).

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Other resources

• Standard precautions for the prevention and control of infections: aide-memoire (Geneva: World Health Organisation; 2022).

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