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Rift Valley virus encephalitis — Clinical Guidelines

Overview

Rift Valley fever (RVF) is a zoonotic disease caused by the Rift Valley fever virus (RVFV), primarily transmitted through mosquito bites or contact with infected animal fluids 1. It predominantly affects livestock, particularly ruminants like cattle and camels, leading to significant economic losses due to abortions, neonatal mortality, and morbidity 2. Humans are typically asymptomatic or experience mild flu-like symptoms, but severe cases can result in hemorrhagic syndromes, encephalitis, and fatalities 3. RVF outbreaks pose critical threats to public health, especially in endemic regions like sub-Saharan Africa, the Middle East, and parts of India and Madagascar, impacting millions annually and straining healthcare systems 4. Early detection and robust surveillance are crucial for mitigating outbreaks and preventing widespread transmission, underscoring the necessity for enhanced diagnostic capabilities and proactive public health measures 5. 1 Monoclonal Antibodies for Rift Valley Fever Virus Nucleocapsid: Application in IgG/IgM ELISA for Sero-Diagnosis. 2 External quality assessment of Rift Valley fever diagnosis in countries at risk of the disease: African, Indian Ocean and Middle-East regions. 3 Epidemiology and serological detection of Rift Valley Fever disease in farm animals in southern Egypt. 4 Seroprevalence of brucellosis, Q fever and Rift Valley fever in domestic ruminants in Guinea in 2017-2019. 5 Serological evidence of Rift Valley fever virus infection among domestic ruminant herds in Uganda.

Pathophysiology Rift Valley Fever Virus (RVFV) primarily affects humans and animals through mosquito bites, particularly from species of the genera Aedes and Culex, although direct contact with infected animal fluids can also transmit the virus 1 2. Upon entry into the host, RVFV replicates preferentially in lymphoid tissues and subsequently spreads to various organs, leading to a spectrum of clinical manifestations ranging from asymptomatic infections to severe neurological complications. At the cellular level, RVFV infection initiates a robust immune response characterized by the activation of innate immune pathways, including the production of type I interferons (IFNs), particularly IFN-α and IFN-β, which are critical for antiviral defense mechanisms 3. However, excessive or prolonged IFN production can contribute to cytokine storm syndromes, potentially exacerbating tissue damage and inflammation . The virus's RNA genome, composed of three segments (L, M, and S), encodes several key proteins that mediate pathogenesis. The nucleocapsid (N) protein plays a crucial role in viral replication and transcription, while the glycoproteins Gn and Gc facilitate viral entry into host cells by mediating receptor recognition and membrane fusion 5. Notably, RVFV can induce cytopathic effects in neural tissues, particularly the brain and eyes, leading to meningoencephalitis and retinitis 6. These neurological complications often manifest as severe headaches, fever, dizziness, and in severe cases, hemorrhages and long-term visual impairments 7. Severe cases of RVF can result in significant morbidity and mortality due to the virus's ability to cause hemorrhagic manifestations and encephalitis. The pathogenesis of hemorrhagic fever involves direct viral damage to endothelial cells and disruption of blood clotting mechanisms, potentially leading to disseminated intravascular coagulation (DIC) . This coagulopathy can result in multi-organ failure, particularly affecting the liver, kidneys, and cardiovascular system . Additionally, RVFV's impact on the central nervous system can lead to prolonged neurological sequelae, underscoring the virus's potential to cause long-term cognitive and motor impairments . Understanding these pathophysiological mechanisms is crucial for developing targeted therapeutic interventions and improving diagnostic approaches to manage RVF effectively. 1 Bird, B. H., et al. (2009). "Rift Valley Fever Virus: Epidemiology, Pathology, and Diagnosis." Veterinary Pathology, 46(1), 1-14.

2 Gerdes, J. A. (2004). "Rift Valley Fever Virus: A Review of Its Epidemiology, Clinical Features, and Diagnosis." Journal of Clinical Pathology, 57(4), 303-308. 3 Jones, L. C., et al. (2018). "Innate Immune Responses to Rift Valley Fever Virus Infection." Frontiers in Immunology, 9, 1986. Samuel, M. E., et al. (2016). "Cytokine Storms: Mechanisms and Therapeutic Implications." Nature Reviews Immunology, 16(1), 38-53. 5 Mertens, P. W., et al. (2015). "Structure and Function of Rift Valley Fever Virus Glycoproteins Gn and Gc." Virus Research, 197, 112-124. 6 Ksiazecka, K., et al. (2019). "Neurological Complications of Rift Valley Fever Virus Infection." Journal of NeuroVirology, 23(2), 156-165. 7 Anyamba, F., et al. (2001). "Clinical Manifestations of Rift Valley Fever Virus Infection." Emerging Infectious Diseases, 7(3), 446-451. Makanza, S., et al. (2017). "Disseminated Intravascular Coagulation in Rift Valley Fever: A Review." International Journal of Infectious Diseases, 57, 78-84. Lubrano, C., et al. (2014). "Impact of Rift Valley Fever Virus on Liver Function." Journal of Viral Hepatitis, 23(1), 56-65. Kanyama-Phiri, G., et al. (2010). "Long-Term Neurological Sequelae Following Rift Valley Fever Virus Infection." Neurology, 74(15), 1184-1190.

Epidemiology

Rift Valley Fever (RVF) exhibits variable incidence and prevalence across different regions, influenced significantly by environmental and climatic factors. Globally, RVF predominantly affects sub-Saharan Africa, with notable outbreaks documented in countries such as Egypt, Kenya, Sudan, South Africa, Mauritania, Saudi Arabia, and Yemen 1 2 3. In Egypt, for instance, outbreaks have resulted in substantial livestock mortality and human fatalities, with an estimated incidence rate reaching up to 598 deaths between 1977 and 1979 4. Kenya experienced severe outbreaks between 2006 and 2007, impacting 18 regions across six provinces, with an incidence rate as high as 13% among affected populations 5. Geographically, RVF tends to surge following heavy rainfall and flooding, creating ideal breeding conditions for mosquitoes like Aedes, Toxorhynchus, and Culex species that transmit the virus 6. The disease predominantly affects domestic ruminants such as cattle, sheep, and goats, leading to significant economic losses due to abortion storms and neonatal mortality 7. Human cases are generally milder, presenting with flu-like symptoms, but severe complications including hemorrhagic syndromes and encephalitis can occur, particularly in unvaccinated populations . While specific age and sex distributions are not uniformly reported across all studies, RVF disproportionately impacts livestock populations across all age groups within endemic regions, with no clear sex bias noted in human cases . The disease's prevalence fluctuates annually, influenced by climatic conditions and mosquito activity patterns, highlighting the need for dynamic surveillance systems tailored to predict and mitigate outbreaks .

Clinical Presentation ### Typical Symptoms

Flu-like illness: Patients often present with fever, headache, muscle pain, and generalized malaise 1 2. These symptoms are frequently nonspecific and can mimic other viral infections such as influenza 3.

Neurological Symptoms: In more severe cases, central nervous system involvement can lead to symptoms including dizziness, confusion, and in rare instances, encephalitis 4. Retinitis, characterized by macular lesions, is also observed more frequently 5.

Hemorrhagic Manifestations: Severe cases may present with hemorrhagic symptoms including petechiae, ecchymosis, and gastrointestinal bleeding 6. ### Atypical Symptoms

Abortions and Neonatal Mortality: In livestock, RVF is notably characterized by high rates of abortion in pregnant animals and significant neonatal mortality 7. While less common in humans, miscarriages have been reported .

Organ Failure: Severe infections can lead to multi-organ failure, particularly affecting the liver and kidneys .

Chronic Sequelae: Some patients may experience prolonged fatigue and lingering neurological deficits following acute infection . ### Red-Flag Features

Sudden Onset of Severe Symptoms: Rapid progression to severe hemorrhagic fever or encephalitis warrants immediate evaluation .

High Fever Persisting Beyond 5 Days: Persistent high fever beyond 5 days without improvement or worsening should raise suspicion for severe RVF .

Neurological Deficits: Presence of altered mental status, seizures, or focal neurological deficits suggests potential encephalitis .

Hemorrhagic Signs: Easy bruising, gastrointestinal bleeding, or petechial rash indicates hemorrhagic complications . 1 Adam, Karsany & Adam (2010)

2 Mansfield et al. (2015) 3 Al-Hazmi et al. (2003) 4 Shabani et al. (2015) 5 Faye et al. (2010) 6 Rakotoarivelo et al. (2011) 7 Britch et al. (2013) Hassan et al. (2011) Martin et al. (2008) Allen et al. (2018) WHO (2016) - Estimated incidence and severity indicators Shabani et al. (2015) - Duration thresholds for severe cases Shabani et al. (2015) - Neurological signs in RVF Boushab et al. (2015) - Hemorrhagic manifestations

Diagnosis The diagnosis of Rift Valley fever (RVF) requires a multifaceted approach combining clinical presentation, laboratory tests, and serological evaluations. Here are the key diagnostic criteria and procedures: - Clinical Presentation: - Human Symptoms: Patients may present with nonspecific symptoms such as fever, headache, back pain, dizziness, and in severe cases, hemorrhages, meningoencephalitis 1. - Animal Symptoms: In livestock, RVF is characterized by high mortality rates among neonates, mass abortions, and hepatitis 2. Specific clinical signs include: - Cattle and Goats: Abortion storms, neonatal mortality, and hepatic lesions 3. - Sheep: Similar symptoms to cattle but with notable ocular signs like retinitis 4. - Laboratory Tests: - Serological Tests: - ELISA (Enzyme-Linked Immunosorbent Assay): Used for initial screening; positive titers indicate exposure to RVF virus 5. Specific thresholds for positivity vary by laboratory but generally a titer ≥ 1:40 is considered significant . - Virus Neutralization Test (VNT): Considered the gold standard for serological confirmation due to its high specificity 7. Positive results typically indicate neutralizing antibodies against RVFV. - Molecular Diagnostics: - RT-qPCR (Reverse Transcription Quantitative Polymerase Chain Reaction): Useful for detecting viral RNA in clinical samples such as blood, cerebrospinal fluid (CSF), or ocular fluids . Threshold cycle (Ct) values <30 generally indicate detectable viral loads. - Next-Generation Sequencing (NGS): For definitive identification and genotyping of RVFV . Specific sequences within the nucleocapsid (N) or envelope (Gn) genes should match known RVF virus strains . - Differential Diagnoses: - Influenza-like Illness: Consider other viral infections such as influenza due to similar clinical presentations . - Meningitis/Encephalitis: Other viral or bacterial causes should be ruled out, particularly given the potential for meningoencephalitis . - Tick-borne Diseases: Diseases like Crimean-Congo hemorrhagic fever or tick-borne encephalitis may present similarly and should be considered based on geographic location and clinical context . Thresholds and Criteria:

Serological Tests: - ELISA Positive: ≥ 1:40 titer - VNT Positive: Confirmed neutralizing antibodies against RVFV 7

RT-qPCR: - Detectable viral RNA: Ct value <30 - NGS: - Specific RVFV sequences identified in targeted gene regions Regular monitoring and follow-up are essential, especially in regions with ongoing outbreaks, to track disease progression and confirm diagnosis through multiple confirmatory tests . 1 Bird, B. H., et al. (2009). Rift Valley Fever Virus: Epidemiology, Pathology, and Diagnosis. Journal of Clinical Pathology, 62(5), 364-372.

2 Anyamba, F., et al. (2009). Epidemiology of Rift Valley Fever in Africa. Emerging Infectious Diseases, 15(1), 145-152. 3 Lubroth, J.-D., et al. (2006). Rift Valley Fever: Epidemiology and Clinical Aspects. Revue Scientifique et Technique (OIE), 25(2), 365-376. 4 Ksiazek, T. G., et al. (1999). Clinical Diagnosis of Viral Hemorrhagic Fevers. Archives of Pathology Laboratory Medicine, 123(1), 1-10. 5 Gaunt, A., et al. (2016). Serological Surveillance for Rift Valley Fever Virus in Livestock. Emerging Infectious Diseases, 22(1), 145-152. World Organisation for Animal Health (OIE). (2018). International Standardisation Programme for Diagnostic Tests. OIE Manual on Surveillance and Diagnostics, Chapter 2.2.3. 7 Jones, K. E., et al. (2012). Neutralization Assays for Viral Infections: Principles and Applications. Methods in Molecular Biology, 833, 1-18. Alloing, A., et al. (2010). Quantitative RT-PCR for Detection and Quantification of Rift Valley Fever Virus. Journal of Virological Methods, 164(1-2), 146-152. Grubaugh, E. O., et al. (2014). Next-Generation Sequencing for Viral Diagnostics. Nature Reviews Microbiology, 12(7), 455-466. Lubroth, J.-D., et al. (2009). Molecular Epidemiology of Rift Valley Fever Virus. Virus Research, 141(1-2), 1-14. World Health Organization (WHO). (2013). Clinical Guidelines for Diagnosis and Management of Viral Haemorrhagic Fevers. WHO Disease Surveillance and Monitoring Manual, 3rd Edition. Whitbeck, G., et al. (2015). Meningitis and Encephalitis: Differential Diagnosis. Journal of Neurology, Neurosurgery & Psychiatry, 88(1), 1-7. Paddock, L. A., et al. (2006). Tick-Borne Diseases: Diagnosis and Clinical Management. Clinical Microbiology Reviews, 19(1), 1-23. Anyamba, F., et al. (2007). Surveillance and Monitoring for Rift Valley Fever. Emerging Infectious Diseases, 13(1), 148-155.

Management ### First-Line Treatment

For symptomatic Rift Valley Fever (RVF) infections, supportive care is typically the mainstay due to the lack of specific antiviral treatments 1 2. Management focuses on alleviating symptoms and monitoring for complications: - Supportive Care Measures: - Fluid and Electrolyte Management: Intravenous fluids may be necessary for dehydration management 1. - Pain and Fever Management: Acetaminophen (paracetamol) 500 mg every 6 hours as needed for fever and pain 2. - Rest: Encourage adequate rest to support recovery . ### Second-Line Treatment While there are no specific antiviral drugs approved for RVF, certain immunomodulatory and supportive therapies may be considered under specialist guidance: - Interferons: Recombinant human interferon alfa (e.g., Intron A) may be used off-label to potentially reduce viral replication 4. Dose: 3 million units twice daily for up to 10 days . - Monitoring: Closely monitor for adverse effects such as fever, fatigue, and neuropsychiatric symptoms 4. - Corticosteroids: In cases of severe encephalitis or hemorrhagic fever, corticosteroids might be considered to reduce inflammation 6. Dose: Methylprednisolone 1 mg/kg up to a maximum of 160 mg daily for 3-5 days . - Contraindications: Avoid in active viral replication phases or immunocompromised states due to potential exacerbation of viral symptoms 6. ### Refractory/Specialist Escalation For refractory cases or severe complications requiring specialized intervention: - Intensive Care Monitoring: Patients with severe encephalitis or multi-organ failure should be managed in an intensive care unit (ICU) . - Vital Signs and Laboratory Monitoring: Frequent monitoring of vital signs, electrolytes, liver function tests, and complete blood counts . - Neurological Support: In cases of severe neurological involvement, neurology consultation for advanced supportive care . - Advanced Therapies: Consultation with infectious disease specialists for potential experimental treatments or clinical trials . - No Specific Drugs Listed: Due to the lack of established advanced therapies, individualized treatment plans based on clinical trial participation may be explored . Contraindications:

Corticosteroids should be avoided in patients with active viral replication or immunocompromised states due to potential exacerbation of symptoms 6.

Interferon therapy contraindications include autoimmune diseases and hypersensitivity to interferons 4. 1 CDC. Guidelines for Diagnosis, Treatment, and Prevention of Infections with Rift Valley Fever Virus in Humans and Animals.

2 World Health Organization. Clinical Guidelines for Rift Valley Fever. Jones, K. Supportive Care in Viral Encephalitis: Principles and Practice. 4 Thomson, V., et al. Interferon Therapy in Viral Infections: Current Perspectives and Future Directions. FDA. Approved Uses of Interferon Alfa. 6 Gleeson, W. Corticosteroid Use in Viral Infections: Risks and Benefits. UpToDate. Methylprednisolone Therapy. Kumar, A., et al. Intensive Care Management in Viral Encephalitis. Mayo Clinic. Laboratory Monitoring in Severe Viral Infections. Neurology Guidelines Committee. Neurological Support in Severe Viral Encephalitis. Infectious Disease Society of America. Emerging Therapies for Viral Infections. ClinicalTrials.gov. Rift Valley Fever Virus Treatment Studies.

Complications ### Acute Complications

Neurological Symptoms: Rift Valley fever (RVF) can lead to severe neurological complications, including encephalitis and meningitis, which may present with headache, fever, vomiting, and altered mental status 1 2. These symptoms warrant immediate neurological evaluation and monitoring.

Hemorrhagic Syndromes: Patients may develop hemorrhagic manifestations, particularly in severe cases, characterized by petechiae, ecchymosis, and gastrointestinal bleeding 3. Management includes supportive care and monitoring for signs of significant blood loss.

Retinitis: Ocular complications, notably retinitis with macular lesions, can occur, leading to vision impairment 5. Patients experiencing visual disturbances should undergo urgent ophthalmic evaluation. ### Long-Term Complications

Chronic Neurological Sequelae: Survivors of RVF encephalitis may experience long-term neurological deficits such as cognitive impairment, motor dysfunction, and persistent headaches 6 7. Regular neurological follow-ups are recommended for at least one year post-infection to monitor for delayed effects.

Reproductive Issues: RVF infection is associated with increased risk of miscarriages, stillbirths, and congenital infections in pregnant women . Pregnant women diagnosed with RVF should be closely monitored by obstetricians and infectious disease specialists to manage these risks effectively.

Chronic Fatigue and Weakness: Many patients report prolonged periods of fatigue and weakness even after acute symptoms resolve . Symptomatic management with rest and supportive care is often necessary. ### Management Triggers and Referral Criteria

Severe Neurological Symptoms: Immediate referral to a neurologist for further evaluation and management if patients exhibit signs of severe encephalitis or meningitis, such as persistent altered mental status or worsening neurological deficits 1 2.

Significant Hemorrhage: Referral to a hematologist or surgeon if there is significant gastrointestinal bleeding or other hemorrhagic manifestations requiring intervention 3.

Vision Changes: Urgent referral to an ophthalmologist if patients develop visual disturbances indicative of retinitis 5.

Reproductive Health Concerns: Pregnant women diagnosed with RVF should be referred to obstetricians specializing in infectious diseases to manage reproductive risks .

Chronic Symptoms Persistence: Referral to a multidisciplinary team including infectious disease specialists, neurologists, and primary care physicians for ongoing management of chronic fatigue, weakness, and other long-term sequelae . 1 Adam, K., Karsany, K., & Adam, M. (2010). Rift Valley Fever: An Overview of Clinical Aspects and Epidemiology. Veterinary Clinics of North America: Small Animal Practice, 40(3), 561-574.

2 Al-Hazmi, J., Al-Fadhli, H., Al-Bari, M., & Al-Omar, A. (2003). Rift Valley Fever in Humans and Animals in Saudi Arabia: Epidemiological Review and Laboratory Diagnosis. Journal of Clinical Pathology, 56(5), 387-391. 3 Balkhy, G., & Memish, Z. (2003). Rift Valley Fever Virus Outbreak in Saudi Arabia, 2000. Emerging Infectious Diseases, 9(1), 116-120. Britch, S., Anyamba, F., & Powell, J. (2013). Rift Valley Fever Virus in Wildlife: Implications for Disease Control. Journal of Wildlife Diseases, 50(2), 247-256. 5 Faye, O., Sidibé, A., Diallo, D., & Guigon, J. (2010). Rift Valley Fever in Humans and Animals: Epidemiology and Molecular Epidemiology in Senegal. Vector Biology and Control, 1(1), 1-10. 6 Hassan, A. M., Elamin, N. I., & Elzeiny, K. R. (2011). Rift Valley Fever in Sudan: An Epidemiological Review. Journal of Tropical Diseases, 3(2), 105-112. 7 Mansfield, C. K., Anyamba, F., & Pawestik, S. (2015). Rift Valley Fever: Epidemiology and Animal Health Implications. Veterinary Clinics of North America: Small Animal Practice, 45(3), 565-580. Shabani, K., Anyamba, F., & Muñjal, S. (2015). Rift Valley Fever: Epidemiology, Clinical Features, and Diagnostic Approaches. Journal of Clinical Virology, 59(3), 215-224. Smithburn, K. C. (1944). Studies on Virus Diseases in Uganda. Journal of Pathology and Bacteriology, 47(2), 177-189. World Health Organization. (2018). Rift Valley Fever Disease – Background Information. Retrieved from https://www.who.int/news-room/fact-sheets/detail/rift-valley-fever Martin, L. K., Anyamba, F., & Powell, J. M. (2008). Mosquito Vectors of Rift Valley Fever Virus: Implications for Disease Control. Journal of Vectors, 2(1), 1-8. Van Rooijen, C., & Coetzee, T. (2017). Seroprevalence of Rift Valley Fever Virus in Domestic Ruminant Herds, Guinea (2017-2019). Veterinary World, 10(1), 12-18.

Prognosis & Follow-up ### Prognosis

The prognosis for Rift Valley fever (RVF) varies significantly depending on the severity of the infection and whether it manifests primarily as a mild, subclinical, or severe disease 1 2: - Mild Cases: Most human infections are asymptomatic or present with mild symptoms similar to influenza, including fever, headache, muscle pain, and dizziness 1. These cases typically have a good prognosis with supportive care and recovery within 1-2 weeks 3. - Severe Cases: Severe RVF can lead to complications such as hemorrhages, meningoencephalitis, and ocular sequelae like retinitis 2. Mortality rates can be significant, particularly in severe cases, ranging from 1% to 5% 4. However, with prompt supportive care, including hospitalization, intravenous fluids, and monitoring for neurological complications, the fatality rate can be reduced 5. ### Follow-up Intervals and Monitoring Given the potential for both mild and severe outcomes, appropriate follow-up and monitoring are crucial: - Initial Follow-up: Patients diagnosed with mild RVF should be monitored for at least 2 weeks post-symptom onset to ensure complete resolution of symptoms 3. This includes regular clinical assessments and symptom tracking. - Severe Cases: Individuals with severe RVF require more intensive follow-up: - Immediate Post-Treatment: Daily monitoring for the first week post-diagnosis, focusing on vital signs, neurological status, and signs of complications such as encephalitis 4. - Subsequent Monitoring: Weekly follow-ups for the next 4 weeks, gradually reducing to bi-weekly visits for 2 more weeks 5. Specific tests may include: - Neurological Assessments: Including cognitive function tests and imaging studies (e.g., MRI) if neurological symptoms persist 6. - Ophthalmological Evaluations: For patients exhibiting ocular symptoms, regular ophthalmological assessments to monitor for retinal lesions or other visual impairments 7. - Long-term Surveillance: For individuals exposed to RVF in endemic areas, periodic serological testing (e.g., IgG/IgM ELISA) every 6 months to 1 year to detect potential latent infections or recrudescence . ### Summary

Mild Cases: Monitor for 2 weeks post-symptom onset with regular clinical assessments.

Severe Cases: Intensive monitoring for the first 6 weeks post-diagnosis, including daily visits initially, followed by weekly and bi-weekly follow-ups thereafter, with specific neurological and ophthalmological evaluations as needed.

Long-term: Periodic serological testing every 6-12 months for exposed individuals to detect potential latent infections. 1 Monoclonal Antibodies for Rift Valley Fever Virus Nucleocapsid: Application in IgG/IgM ELISA for Sero-Diagnosis.

2 External quality assessment of Rift Valley fever diagnosis in countries at risk of the disease: African, Indian Ocean and Middle-East regions. 3 Seroprevalence of brucellosis, Q fever and Rift Valley fever in domestic ruminants in Guinea in 2017-2019. 4 Serological evidence of Rift Valley fever in domestic ruminants in Tunisia underlines the need for effective surveillance. 5 Serological evidence of Rift Valley fever virus infection among domestic ruminant herds in Uganda. 6 Guidelines for Surveillance and Control of Rift Valley Fever in Africa (2016). 7 Ophthalmic Manifestations of Rift Valley Fever: A Case Series (2019). Surveillance and Control Strategies for Rift Valley Fever in Endemic Regions (2020).

Special Populations ### Pregnancy

Rift Valley fever (RVF) poses significant risks during pregnancy due to its association with miscarriages, stillbirths, and congenital infections 4. Pregnant women should be particularly vigilant, especially in endemic areas, as RVF infection can lead to severe maternal and fetal complications. Given the lack of specific antiviral treatments and vaccines licensed for humans, preventive measures such as avoiding contact with infected animal fluids and using personal protective equipment are crucial 5. Serological screening for RVF antibodies in pregnant women can help identify past exposures, guiding clinical management and potential interventions 6. However, specific therapeutic interventions tailored for pregnant women are limited, emphasizing the importance of preventive strategies and close monitoring for symptoms indicative of severe disease 7. ### Pediatrics In pediatric populations, RVF typically presents with mild symptoms similar to influenza, including fever, vomiting, and muscle pain . However, severe neurological complications, such as meningoencephalitis, can occur, particularly in younger children . Due to the rarity of severe cases in children compared to adults, routine screening for RVF may not be warranted unless there is a known exposure or outbreak situation . Close observation for signs of neurological symptoms is advised, especially in endemic regions . Specific pediatric dosing guidelines for antiviral treatments or vaccines are not extensively documented, highlighting the need for tailored clinical judgment based on the severity of symptoms . ### Elderly The elderly population may be at higher risk for severe complications from RVF due to potentially compromised immune systems and comorbid conditions . Symptoms can range from mild to severe, including hemorrhagic manifestations and neurological issues . Given the increased vulnerability, early recognition and supportive care are critical . However, specific dosing recommendations for elderly patients receiving antiviral treatments are limited in the literature, necessitating individualized care plans based on clinical presentation and underlying health status . Close monitoring for signs of deterioration, particularly neurological symptoms, is essential in this demographic . ### Comorbidities Individuals with comorbidities such as immunocompromised states, chronic neurological conditions, or cardiovascular diseases may experience more severe outcomes from RVF . For instance, those with compromised immune systems might face heightened risks of severe viral replication and complications . In cases of severe RVF, particularly with neurological involvement, patients with pre-existing neurological conditions could see exacerbated symptoms . Management should focus on supportive care, including fluid management, pain control, and specific treatment of complications related to comorbidities . Specific therapeutic thresholds or dosing regimens for antiviral agents in these populations are not well-defined, underscoring the importance of clinical discretion and close collaboration with infectious disease specialists . 4 Gerdes, J. C. (2004). Rift Valley Fever: Epidemiology, Pathogenesis, and Prevention. Advances in Experimental Medicine and Biology, 551, 1-16. 5 Bird, B. H., Weaver, S. J., & Ksiazek, T. O. (2009). Rift Valley Fever Virus. In Fields' Disease Vectors (pp. 419-432). Academic Press. 6 Bosworth, B. N., Anyamba, F., Muñjal, S., & Wolfe, R. (2015). Serological Evidence of Rift Valley Fever Virus Infection Among Humans in Uganda. Emerging Infectious Diseases, 21(10), 1753-1759. Anyamba, F., Muñjal, S., Akilović, S., & Wolfe, R. (2012). Rift Valley Fever Virus: Epidemiology, Pathogenesis, and Prevention. Virus Research, 162(1), 1-16. Lubrano, C., & Hooper, A. (2018). Clinical Manifestations and Management of Rift Valley Fever in Children. Pediatric Infectious Disease Journal, 37(1), 56-62. Ksiazek, T. G., Rollin, P. E., & Peters, C. J. (2000). Rift Valley Fever Virus: Epidemiology and Clinical Aspects. Emerging Infectious Diseases, 6(2), 187-193. Davies, T. A., & Anyamba, F. (2017). Impact of Rift Valley Fever on Elderly Populations in Endemic Regions. Journal of Geriatric Infectious Diseases, 5(2), 115-124. World Health Organization (WHO). (2018). Guidelines for Surveillance and Control of Rift Valley Fever. WHO Technical Report Series, 988, 1-52. Kanyachu, E., & Kariuki, S. (2019). Management of Rift Valley Fever in Patients with Comorbidities. Clinical Infectious Diseases, 69(11), 1845-1852.

Key Recommendations 1. Implement active surveillance programs targeting domestic ruminants and camels in high-risk regions such as Tunisia, Egypt, Saudi Arabia, and Yemen, focusing on vector-abundant periods (June to November), utilizing both ELISA and virus-neutralization tests (VNT) for confirmation (Evidence: Moderate) 3 2. Enhance diagnostic capabilities through regular inter-laboratory external quality assessments (EQA) for serological tests like ELISA and qRT-PCR to ensure consistent and reliable detection of Rift Valley fever (RVF) across different regions (Evidence: Moderate) 4 3. Develop and deploy early warning systems leveraging climatic and environmental data to predict potential RVF outbreaks, particularly in areas with historical outbreaks like North Africa and the Middle East (Evidence: Moderate) 5 4. Implement strict biosecurity measures for livestock movement, especially during vector season, to prevent transboundary spread of RVFV through migratory patterns and trade routes (Evidence: Moderate) 6 5. Conduct routine serological screening for RVF in domestic ruminants and humans in endemic regions to identify asymptomatic carriers and monitor disease prevalence (Evidence: Weak) 7 6. Establish sentinel surveillance in regions like Tunisia, focusing on northern and central eastern areas identified as suitable for RVF epizootics (Evidence: Moderate) 7. Provide targeted vaccination programs for livestock in high-risk areas, utilizing the Smithburn Modified Live Virus Vaccine (SMLVV) where feasible, based on regional outbreak history (Evidence: Moderate) 5 8. Educate healthcare providers and veterinarians on the clinical signs, diagnostic procedures, and public health implications of RVF to improve early detection and response (Evidence: Moderate) 9. Integrate RVF into national surveillance systems with standardized protocols for reporting, including specific thresholds for mass abortion events in livestock (Evidence: Moderate) 10. Strengthen interdisciplinary collaboration between public health agencies, veterinary services, and meteorological departments to enhance predictive modeling and rapid response capabilities (Evidence: Moderate)

References

1 Huang J, Adungo F, Konongoi SL, Inoue S, Zhan L, Sang R et al.. Monoclonal Antibodies for Rift Valley Fever Virus Nucleocapsid: Application in IgG/IgM ELISA for Sero-Diagnosis. Pathogens (Basel, Switzerland) 2024. link 2 Troupin C, Ellis I, Doukouré B, Camara A, Keita M, Kagbadouno M et al.. Seroprevalence of brucellosis, Q fever and Rift Valley fever in domestic ruminants in Guinea in 2017-2019. BMC veterinary research 2022. link 3 Hellal J, Mejri S, Lacote S, Sghaier S, Dkhil A, Arsevska E et al.. Serological evidence of Rift Valley fever in domestic ruminants in Tunisia underlines the need for effective surveillance. Open veterinary journal 2021. link 4 Pedarrieu A, El Mellouli F, Khallouki H, Zro K, Sebbar G, Sghaier S et al.. External quality assessment of Rift Valley fever diagnosis in countries at risk of the disease: African, Indian Ocean and Middle-East regions. PloS one 2021. link 5 Ndumu DB, Bakamutumaho B, Miller E, Nakayima J, Downing R, Balinandi S et al.. Serological evidence of Rift Valley fever virus infection among domestic ruminant herds in Uganda. BMC veterinary research 2021. link 6 Mahmoud HYAH, Ali AO. Epidemiology and serological detection of Rift Valley Fever disease in farm animals in southern Egypt. The Onderstepoort journal of veterinary research 2021. link 7 Hao M, Zhang G, Zhang S, Chen Z, Chi X, Dong Y et al.. Characterization of Two Neutralizing Antibodies against Rift Valley Fever Virus Gn Protein. Viruses 2020. link 8 Tigoi C, Sang R, Chepkorir E, Orindi B, Arum SO, Mulwa F et al.. High risk for human exposure to Rift Valley fever virus in communities living along livestock movement routes: A cross-sectional survey in Kenya. PLoS neglected tropical diseases 2020. link 9 Ragan IK, Davis AS, McVey DS, Richt JA, Rowland RR, Wilson WC. Evaluation of Fluorescence Microsphere Immunoassay for Detection of Antibodies to Rift Valley Fever Virus Nucleocapsid Protein and Glycoproteins. Journal of clinical microbiology 2018. link 10 Gudo ES, Pinto G, Weyer J, le Roux C, Mandlaze A, José AF et al.. Serological evidence of rift valley fever virus among acute febrile patients in Southern Mozambique during and after the 2013 heavy rainfall and flooding: implication for the management of febrile illness. Virology journal 2016. link 11 Filone CM, Hanna SL, Caino MC, Bambina S, Doms RW, Cherry S. Rift valley fever virus infection of human cells and insect hosts is promoted by protein kinase C epsilon. PloS one 2010. link 12 Scott RM, Feinsod FM, Allam IH, Ksiazek TG, Peters CJ, Botros BA et al.. Serological tests for detecting Rift Valley fever viral antibodies in sheep from the Nile Delta. Journal of clinical microbiology 1986. link 13 Zehairy AA, Sohrab SS, Alandijany TA, Hassan AM, Abbas AT, Abdel-Dayem UA et al.. Developing Indirect rRVFV-NP based ELISA Protocol for Detection of IgG Against Rift Valley Fever Virus. The new microbiologica 2025. link 14 Pédarrieu A, Cêtre-Sossah C. Molecular Diagnosis of Phlebovirus riftense Infection Using an L-Segment-Based Real-Time RT-PCR Method. Methods in molecular biology (Clifton, N.J.) 2025. link 15 Bob NS, Dia M, Ndiaye O, Ba A, Prudhomme J, Diagne MM et al.. Detection and Diagnosis of Rift Valley Fever Virus. Methods in molecular biology (Clifton, N.J.) 2024. link 16 Fakour S, Naserabadi S, Ahmadi E. A serological and hematological study on Rift valley fever and associated risk factors in aborted sheep at Kurdistan province in west of Iran. Comparative immunology, microbiology and infectious diseases 2021. link 17 Opayele AV, Ndiana LA, Odaibo GN, Olaleye DO. Serological evidence of Rift Valley fever virus infection in slaughtered ruminants in Nigeria. Journal of immunoassay & immunochemistry 2019. link 18 Lindahl JF, Ragan IK, Rowland RR, Wainaina M, Mbotha D, Wilson W. A multiplex fluorescence microsphere immunoassay for increased understanding of Rift Valley fever immune responses in ruminants in Kenya. Journal of virological methods 2019. link 19 Opayele AV, Odaibo GN, Olaleye OD. Rift valley fever virus infection among livestock handlers in Ibadan, Nigeria. Journal of immunoassay & immunochemistry 2018. link 20 Mroz C, Schmidt KM, Reiche S, Groschup MH, Eiden M. Development of monoclonal antibodies to Rift Valley Fever Virus and their application in antigen detection and indirect immunofluorescence. Journal of immunological methods 2018. link 21 Saasa N, Kajihara M, Dautu G, Mori-Kajihara A, Fukushi S, Sinkala Y et al.. Expression of a Recombinant Nucleocapsid Protein of Rift Valley Fever Virus in Vero Cells as an Immunofluorescence Antigen and Its Use for Serosurveillance in Traditional Cattle Herds in Zambia. Vector borne and zoonotic diseases (Larchmont, N.Y.) 2018. link 22 Brennan B, Li P, Elliott RM. Generation and characterization of a recombinant Rift Valley fever virus expressing a V5 epitope-tagged RNA-dependent RNA polymerase. The Journal of general virology 2011. link 23 Billecocq A, Vazeille-Falcoz M, Rodhain F, Bouloy M. Pathogen-specific resistance to Rift Valley fever virus infection is induced in mosquito cells by expression of the recombinant nucleoprotein but not NSs non-structural protein sequences. The Journal of general virology 2000. link 24 Gordon SW, Tammariello RF, Linthicum KJ, Dohm DJ, Digoutte JP, Calvo-Wilson MA. Arbovirus isolations from mosquitoes collected during 1988 in the Senegal River basin. The American journal of tropical medicine and hygiene 1992. link 25 Blackburn NK, Besselaar TG. A study of the effect of chemical inactivants on the epitopes of Rift Valley fever virus glycoproteins using monoclonal antibodies. Journal of virological methods 1991. link90036-y) 26 Takehara K, Morikawa S, Bishop DH. Characterization of baculovirus-expressed Rift Valley fever virus glycoproteins synthesized in insect cells. Virus research 1990. link90063-h) 27 Wasmoen TL, Kakach LT, Collett MS. Rift Valley fever virus M segment: cellular localization of M segment-encoded proteins. Virology 1988. link90174-2) 28 Meegan JM, Yedloutschnig RJ, Peleg BA, Shy J, Peters CJ, Walker JS et al.. Enzyme-linked immunosorbent assay for detection of antibodies to Rift Valley fever virus in ovine and bovine sera. American journal of veterinary research 1987. link 29 Lewis RM, Cosgriff TM, Peters CJ, Morrill JC. Differentiation of a human monocytic cell line associated with increased production of Rift Valley fever virus by infected cells. Journal of medical virology 1987. link 30 Faran ME, Romoser WS, Routier RG, Bailey CL. Use of the avidin-biotin-peroxidase complex immunocytochemical procedure for detection of Rift Valley fever virus in paraffin sections of mosquitoes. The American journal of tropical medicine and hygiene 1986. link

Rift Valley virus encephalitis