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Rift Valley Fever

Rift valley fever is an infectious disease caused by rift valley fever virus, an RNA virus that causes hemorrhagic fever in humans and animals, similar to Ebola, Lassa, Marburg, dengue and yellow fever viruses. Humans become infected via aerosols or by ingesting unpasteurized animal milk or after exposure to infected animal blood, body fluids or tissue or following mosquito or other insect bites.


Presentation

Most infected individuals remain asymptomatic or develop a mild form of the disease, consisting of fever, muscle and joint pain, weakness, backache, and headache. The clinical picture may resemble meningitis with neck stiffness photophobia, anorexia, and vomiting. Still, symptoms may be difficult to recognize, especially if the epizootic context is unknown and diagnosis may depend on reliable laboratory techniques.

Severe illness consists of ocular disease, meningoencephalitis, and hemorrhagic fever. Ocular symptoms like blurred or decreased vision signify retinal or macular damage, that might spontaneously resolve or become permanent, leading to vision loss. Central nervous system disease manifests as an intense headache, hallucinations, confusion, seizures, lethargy, and coma, with persistence of neurologic deficit, whereas hemorrhagic fever signifies liver damage and manifests as jaundice, melena, hematemesis, menorrhagia, epistaxis or other mucosal hemorrhages, purpuric rash or ecchymosis. 50% of patients with hemorrhagic fever die within one week of symptom onset. Jaundice, neurologic and hemorrhagic forms have a higher incidence of mortality [1] [2]. Central nervous system disease may be followed by permanent neurologic deficits.

Although abortion is the most prominent trait of this disease in animals, pregnant women, newborns, and small children usually are spared from this infection. The reason for this might be that they usually are not exposed to diseased animals and more efforts are made to prevent their exposure to mosquitoes; if other reasons exist, they are yet to be reported.

Rift valley fever (RVF) induces life-long immunity.

Ocular disease becomes apparent 7-21 days after infection and resolves after 10-12 weeks. Encephalitis may be suspected 1-4 weeks after initial general symptoms of the disease appear, while hemorrhages occurring much sooner i.e. 2-4 days following exposure, entail a poor prognosis.

Fever
  • 24 November 2016 Rift Valley Fever in Niger 29 September 2016 Rift Valley fever in Niger 2 August 2016 Rift Valley fever in China 1 November 2012 Rift Valley fever in Mauritania 12 May 2010 Rift Valley fever in South Africa- update 2 4 May 2010 Rift[who.int]
  • fever virus infection had miscarriages compared with 12 (12%) of 102 women negative for Rift Valley fever virus (p INTERPRETATION: This study is the first to show an association between infection with Rift Valley fever virus and miscarriage in pregnant[ncbi.nlm.nih.gov]
  • Blood specimens collected from both patients were sent for testing for Marburg virus disease, Ebola virus disease, Rift Valley fever (RVF), and Crimean Congo Hemorrhagic fever at the Uganda Virus Research Institute, as part of the viral hemorrhagic fevers[ncbi.nlm.nih.gov]
  • Rift valley fever is an infectious disease caused by rift valley fever virus, an RNA virus that causes hemorrhagic fever in humans and animals, similar to Ebola, Lassa, Marburg, dengue and yellow fever viruses.[symptoma.com]
  • BACKGROUND: Human behavioral factors have been found to be central in the transmission of Rift Valley fever.[ncbi.nlm.nih.gov]
Anorexia
  • The clinical picture may resemble meningitis with neck stiffness photophobia, anorexia, and vomiting.[symptoma.com]
  • The outstanding symptoms were headache, backache, anorexia, prostration and fever. The duration of fever ranged from 2 to 6 days. All the patients recovered without exhibiting any permanent sequelae, but the rapidity of convalescence was variable.[jimmunol.org]
  • In young animals, peracute disease causes anorexia, listlessness, collapse and death. Humans develop malarial-like disease. High risk individuals include farmers, veterinarians and abattoir staff.[web.archive.org]
  • Spontaneous abortions are seen as the hallmark of RVF outbreaks. [4] Pregnant animals can abort at any stage often with 100% of stock aborting. [6] Newborn lambs and kids are highly susceptible to RVF, presenting with pyrexia and anorexia shortly followed[en.wikivet.net]
  • Other signs in livestock include vomiting and diarrhoea, respiratory disease, fever, lethargy, anorexia and sudden death in young animals. The virus belongs to the Bunyavirales order.[en.wikipedia.org]
Aspiration
  • METHODS: Resting mosquitoes were trapped during the rainy and the dry season using a Prokopack aspirator from vegetation, whereas general adult populations were trapped using CDC light traps.[ncbi.nlm.nih.gov]
Vomiting
  • The clinical picture may resemble meningitis with neck stiffness photophobia, anorexia, and vomiting.[symptoma.com]
  • With no specific treatment or effective human vaccine, Rift Valley fever can cause blindness and severe hemorrhaging, leading the victim to vomit blood or even bleed to death.[voanews.com]
  • Vomiting and diarrhoea may involve melaena and haematochezia. Tachycardia, cyanosis, petechiation, haemorrhage and clotting defects are haematological consequences of RVF.[web.archive.org]
  • Some patients develop neck stiffness, sensitivity to light, loss of appetite and vomiting; in these patients the disease, in its early stages, may be mistaken for meningitis.[web.archive.org]
  • Most cases are mild, and involve non-specific symptoms including fever, muscle and joint pain, and headache; neck stiffness and vomiting may also occur.[virology.ws]
Loss of Appetite
  • Some patients develop neck stiffness, sensitivity to light, loss of appetite and vomiting; in these patients the disease, in its early stages, may be mistaken for meningitis.[web.archive.org]
Abdominal Pain
  • pain, photosensitivity, anorexia, excessive salivation and decreased milk production.[en.wikivet.net]
Right Upper Quadrant Pain
  • Our data reveal an identifiable clinical syndrome suggestive of severe RVF, characterized by fever, large-joint arthralgia, and gastrointestinal complaints and later followed by jaundice, right upper-quadrant pain, and delirium, often coinciding with[ncbi.nlm.nih.gov]
Thrombosis
  • RVFV infection in humans usually causes a self-limiting, acute and febrile illness; however, a small number of cases progress to neurological disorders, partial or complete blindness, hemorrhagic fever, or thrombosis.[ncbi.nlm.nih.gov]
  • Malignant Aspergillus flavus Otitis Externa with Jugular Thrombosis. Emerg Infect Dis. 2019;25(4):830-832. Moniot M, Montava M, Ranque S, et al. Malignant Aspergillus flavus Otitis Externa with Jugular Thrombosis.[cdc.gov]
Tachycardia
  • Tachycardia, cyanosis, petechiation, haemorrhage and clotting defects are haematological consequences of RVF. The respiratory disease of RVF is non-specific: Purulent nasal discharge, epistaxis, tachypnoea and dyspnoea.[web.archive.org]
Jaundice
  • Jaundice, neurologic and hemorrhagic forms have a higher incidence of mortality. Central nervous system disease may be followed by permanent neurologic deficits.[symptoma.com]
  • Our data reveal an identifiable clinical syndrome suggestive of severe RVF, characterized by fever, large-joint arthralgia, and gastrointestinal complaints and later followed by jaundice, right upper-quadrant pain, and delirium, often coinciding with[ncbi.nlm.nih.gov]
  • In older animals, the liver is enlarged and inflamed, with many foci of necrosis which are bronzed and jaundiced. The gall bladder may also be distended and haemorrhagic.[web.archive.org]
  • Haemorrhagic fever form: The symptoms of this form of the disease appear two to four days after the onset of illness, and begin with evidence of severe liver impairment, such as jaundice.[web.archive.org]
Petechiae
  • On necropsy, in the viraemic stage, widespread petechiae and ecchymoses on serous surfaces and organs will be seen and extravasated blood present in the body cavities.[web.archive.org]
  • On post mortem during the viraemic stage, widespread petechiae and ecchymoses on serous surfaces and organs will be seen and present in the body cavities.[en.wikivet.net]
Myalgia
  • The usual presentation is of sudden onset fever, myalgia, biphasic behaviour and gastrointestinal disease.[web.archive.org]
  • The usual presentation is of sudden onset fever, myalgia, biphasic behaviour and gastrointestinal disease. [4] Diagnosis Following infection viraemia is often high (though short lived) so the virus can be easily detected in the blood shortly after.[en.wikivet.net]
Arthralgia
  • Our data reveal an identifiable clinical syndrome suggestive of severe RVF, characterized by fever, large-joint arthralgia, and gastrointestinal complaints and later followed by jaundice, right upper-quadrant pain, and delirium, often coinciding with[ncbi.nlm.nih.gov]
Epistaxis
  • […] disease manifests as an intense headache, hallucinations, confusion, seizures, lethargy, and coma, with persistence of neurologic deficit, whereas hemorrhagic fever signifies liver damage and manifests as jaundice, melena, hematemesis, menorrhagia, epistaxis[symptoma.com]
  • The respiratory disease of RVF is non-specific: Purulent nasal discharge, epistaxis, tachypnoea and dyspnoea. Fever, lymphadenopathy, depression and lethargy usually accompany infection. Hepatitis may cause consequent photosensitisation.[web.archive.org]
Headache
  • Most infected individuals remain asymptomatic or develop a mild form of the disease, consisting of fever, muscle and joint pain, weakness, backache, and headache.[symptoma.com]
  • On March 9, 2016, a male butcher from Kabale District, Uganda, aged 45 years, reported to the Kabale Regional Referral Hospital with fever, fatigue, and headache associated with black tarry stools and bleeding from the nose.[ncbi.nlm.nih.gov]
  • Mild symptoms include hemorrhagic fever, muscle pains and headaches whereas severe symptoms range from loss of sight within weeks of infection to brain inflammation, which can lead to headaches and seizures. ...[allafrica.com]
  • The mild symptoms may include: fever, muscle pains, and headaches which often last for up to a week.[en.wikipedia.org]
  • The virus also infects humans, commonly causing malaise, fever and headaches; in epidemics in North Africa, encephalitis and death have also occurred.[epi.ufl.edu]
Meningism
  • The clinical picture may resemble meningitis with neck stiffness photophobia, anorexia, and vomiting.[symptoma.com]
  • In the first four months of 2015, Niger reported more than 1500 cases of meningococcal meningitis, including 147 deaths. China has reported 20 cases of avian influenza A (H7N9) this year, including four deaths.[blogs.scientificamerican.com]
  • Some patients develop neck stiffness, sensitivity to light, loss of appetite and vomiting; in these patients the disease, in its early stages, may be mistaken for meningitis.[web.archive.org]
  • Using a population-based surveillance system for pneumonia, sepsis, and meningitis, we estimated S. aureus bacteremia incidence and the case-fatality ratio in children S. aureus .[cdc.gov]

Workup

Laboratory techniques used in order to establish the diagnosis include reverse transcriptase-polymerase chain reaction (RT-PCR) [3] [4], virus isolation in cell cultures [5], enzyme-linked immunoassay (ELISA) to detect viral antigens [6] [7], immunoglobulin IgM and IgG [8] and real-time reverse transcription-loop-mediated isothermal amplification assays (RT-LAMP) [9] [10], a new, highly specific and sensitive diagnostic test. Samples should be handled with caution and processed in specialized facilities, as they might be a bio- hazard. The virus is isolated from serum, liver, spleen or brain tissue. Rapid virus identification in severe cases is extremely important as patients need special management.

Immunological viral antigen detection methods include agar gel immunodiffusion and immunostaining on impression smears or on cryostat sections of liver, spleen, and brain, while histopathological examination reveals specific characteristics [11] [12]. Sandwich ELISA for antigen detection (sAg-ELISA) is a new technique to identify the disease and it is less dangerous to laboratory personnel [13] [14].

Antibody detection methods include hemagglutination-inhibition, complement fixation, indirect immunofluorescence which aim to prove seroconversion and virus neutralization test which is considered to be the gold standard [11] [8].

Treatment

  • The patient developed multiorgan dysfunction and gradually recovered with continuous renal replacement therapy and a short regimen of methylprednisolone treatment.[ncbi.nlm.nih.gov]
  • Currently, there are no treatments or fully licensed vaccines for this virus. Using high-throughput RNAi screening, we identified canonical Wnt signaling as an important host pathway regulating RVFV infection.[ncbi.nlm.nih.gov]
  • Treatment and vaccines As most human cases of RVF are relatively mild and of short duration, no specific treatment is required for these patients. For the more severe cases, the predominant treatment is general supportive therapy.[web.archive.org]
  • Treatment No treatment is available. Control Modified live and inactivated vaccines are available. Live vaccination is only recommended in non-pregnant animals due to its ability to cause abortion and neurological deficits in lambs.[web.archive.org]
  • With no specific treatment or effective human vaccine, Rift Valley fever can cause blindness and severe hemorrhaging, leading the victim to vomit blood or even bleed to death.[voanews.com]

Prognosis

  • Encephalitis may be suspected 1-4 weeks after initial general symptoms of the disease appear, while hemorrhages occurring much sooner i.e. 2-4 days following exposure, entail a poor prognosis.[symptoma.com]
  • D’Agati and Ibrahim Batal, Donor APOL1 high-risk genotypes are associated with increased risk and inferior prognosis of de novo collapsing glomerulopathy in renal allografts, Kidney International, 10.1016/j.kint.2018.06.024, (2018). Sanaa M.[doi.org]

Etiology

  • Suspected VHF in which the etiology is uncertain should be initially managed with the most cautious infection control measures.[ncbi.nlm.nih.gov]
  • By early December 2016, accumulating disease data suggested that the outbreak of Rift Valley Fever was of modest size, and plans to explore other etiologies were formulated. References: WHO: Disease Outbreak News, 29 September 2016.[cdc.gov]
  • That this “top 10” list of agricultural diseases on the move includes, exclusively, conditions of viral etiology is not coincidental.[doi.org]

Epidemiology

  • For the given (CDC) data set, Monte Carlo simulations indicate that only three parameters of the epidemiological model are practically identifiable when the immune model parameters are fixed.[ncbi.nlm.nih.gov]
  • Epidemiological information describing the methods and parameters of RVF transmission and its dependence on climatic factors are used to develop a new spatio-temporal mathematical model that simulates these dynamics and can predict the impact of changes[ncbi.nlm.nih.gov]
  • We review the history of RVF outbreaks in eastern Africa to identify the epidemiological factors that could have influenced its increasing severity in humans.[ncbi.nlm.nih.gov]
  • Author information 1 Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.[ncbi.nlm.nih.gov]
  • Gov't MeSH terms Animals Disease Outbreaks Endemic Diseases Humans Rift Valley Fever/epidemiology Rift Valley Fever/prevention & control* Rift Valley fever virus/immunology* Treatment Outcome United States/epidemiology Vaccines, Attenuated/administration[ncbi.nlm.nih.gov]
Sex distribution
Age distribution

Pathophysiology

  • Serial blood samples from these men were analyzed for a series of biomarkers specific for various aspects of human pathophysiology including inflammation, endothelial function and coagulopathy.[ncbi.nlm.nih.gov]

Prevention

  • Overall knowledge score on RVF was found to be a significant predictor of good preventive practice of the disease (OR 1.073, 95% CI 1.047-1.101).[ncbi.nlm.nih.gov]
  • KEYWORDS: Emerging Disease; Rift Valley fever; arboviruses; modelling; mosquitoes; prevention and control; vector biology[ncbi.nlm.nih.gov]
  • Author information 1 Faculty of Medicine, King Fahad Medical City, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Kingdom of Saudi Arabia. 2 United States Public Health Service (USPHS) at the Centers for Disease Control and Prevention[ncbi.nlm.nih.gov]
  • Author information 1 Viral Special Pathogens Branch, Division of High Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA; One Health Institute, School of Veterinary Medicine, University of California[ncbi.nlm.nih.gov]
  • Nairobi, Kenya. 2 Division of Infectious Diseases and Global Medicine, Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America. 3 Global Disease Detection Program, United States Center for Disease Control and Prevention[ncbi.nlm.nih.gov]

References

Article

  1. Laughlin L, Meegan J, Strausbaugh L. Epidemic Rift Valley fever in Egypt: Observations of the spectrum of human illness. Trans. R. Soc. Trop. Med. Hyg. 1979;73:630–633.
  2. Madani T, Al-Mazrou Y, Al-Jeffri M, et al. Rift Valley fever epidemic in Saudi Arabia: Epidemiological, clinical, and laboratory characteristics. Clin. Infect. Dis. 2003;37:1084–1092.
  3. Garcia S, Crance J, Billecocq A, et al. Quantitative real-time PCR detection of Rift Valley fever virus and its application to evaluation of antiviral compounds. J. Clin. Microbiol. 2001;39:4456–4461.
  4. Ibrahim M, Turell M, Knauert F, Lofts R. Detection of Rift Valley fever virus in mosquitoes by RT-PCR. Mol. Cell. Probes 1997;11:49–53.
  5. Anderson G, Saluzzo J, Ksiazek T, et al. Comparison of in vitro and in vivo systems for propagation of Rift Valley fever virus from clinical specimens. Res. Virol. 1989;140:129–138.
  6. Meegan J, Le Guenno B, Ksiazek T, et al. Rapid diagnosis of Rift Valley fever: A comparison of methods for the direct detection of viral antigen in human sera. Res. Virol. 1989;140:59–65.
  7. Niklasson B, Grandien M, Peters C, Gargan T. Detection of Rift Valley fever virus antigen by enzyme-linked immunosorbent assay. J. Clin. Microbiol. 1983;17:1026–1031.
  8. Swanepoel R, Struthers J, Erasmus M, et al. Comparison of techniques for demonstrating antibodies to Rift Valley fever virus. J. Hyg. 1986;97:317–329.
  9. Le Roux C, Kubo T, Grobbelaar A, van Vuren P, Weyer J, Nel L. Development and evaluation of a real-time reverse transcription-loop-mediated isothermal amplification assay for rapid detection of Rift Valley fever virus in clinical specimens. J. Clin. Microbiol. 2009;47:645–651.
  10. Peyrefitte C, Boubis L, Coudrier D, et al. Real-time reverse-transcription loop-mediated isothermal amplification for rapid detection of Rift Valley fever virus. J. Clin. Microbiol. 2008;46:3653–3659.
  11. Gerdes G. Rift Valley Fever. In: Manual of diagnostic yeasts and vaccines for terrestrial animals (mammals, birds and bees), Office International des Epizooties, Paris, 2004;185–194.
  12. Swanepoel R, Coetzer J. Rift Valley fever. In: Coetzer J, Tustin R.C. (Eds.), Infectious diseases of livestock, Oxford University Press Southern Africa, Cape Town, 2004;1037–1070.
  13. van Vuren P, Paweska J. Laboratory safe detection of nucleocapsid protein of Rift Valley fever virus in human and animal specimens by a sandwich ELISA. J. Virol. Meth. 2009;157:15–24.
  14. Pepin M, Bouloy M, Bird B, Kemp A, Paweska J. Rift valley fever virus (Bunyaviridae:Ohlebovirus): an update on pathogenesis, molecular epidemiology, vectors, diagnostics and prevention. Vet Res. 2010;41(6): 61.

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Last updated: 2019-07-11 21:34