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BrianGroen/sandbox
DateOutbreak 5 December 2015 - ongoing[1]
Casualties
  • Note: Current figures are derived from various WHO sources. No exact data is available.
Country Cases Deaths Last update
Angola Angola 2,420 298 20 May 2016[1]
Democratic Republic of the Congo DRC 453 45 20 May 2016[1][2]
Kenya Kenya 2 1 20 May 2016[1][3]
China China 11 - 20 May 2016[1]
Total 2,886 344 As of 20 May 2016

The World Health Organization(WHO) has issued a warning of a deadly outbreak of Yellow fever on 19 May 2016. The WHO confirmed that it does not warrant a Public Health Emergency of International Concern(PHEIC) warning but reiterated the need for a national and international concern and action to stop the spread of the deadly disease.[4]

Overview

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Yellow fever virus
Virus classification
Group:
Group IV ((+)ssRNA)
Order:
Unassigned
Family:
Flaviviridae
Genus:
Flavivirus
Species:
Yellow fever virus

Yellow fever is an acute viral disease.[5] In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches.[5] Symptoms typically improve within five days.[5] In some people within a day of improving, the fever comes back, abdominal pain occurs, and liver damage begins causing yellow skin.[5] If this occurs, the risk of bleeding and kidney problems is also increased.[5]

The disease is caused by the yellow fever virus and is spread by the bite of an infected female mosquito.[5] It infects only humans, other primates, and several species of mosquitoes.[5] In cities, it is spread primarily by mosquitoes of the Aedes aegypti species.[5] The virus is an RNA virus of the genus Flavivirus.[6] The disease may be difficult to tell apart from other illnesses, especially in the early stages.[5] To confirm a suspected case, blood sample testing with polymerase chain reaction is required.[7]

A safe and effective vaccine against yellow fever exists and some countries require vaccinations for travelers.[5] Other efforts to prevent infection include reducing the population of the transmitting mosquito.[5] In areas where yellow fever is common and vaccination is uncommon, early diagnosis of cases and immunization of large parts of the population is important to prevent outbreaks.[5] Once infected, management is symptomatic with no specific measures effective against the virus.[5] The second and more severe phase results in death in up to half of people without treatment.[5][8]

Angolan outbreak and subsequent spread

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Index case

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Aedes aegypti feeding

The first case was reported in 21 January 2016 to the WHO by the National IHR Focal Point, a division of the organization in Angola. The index case was a patient in the Viana municipality of the Luanda Province in Angola. The onset date was reported as 5 December 2016.[9]

Angolan outbreak

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The first cases was reported in December 2015 in Luanda, the capital city of Angola.[10] The "potential for explosive spread in urban settings with high mortality and also the risk of international spread" is of particular note according to Bruce Aylward, the WHO chief on health emergencies.[10].On 20 May 2016, the WHO confirmed 298 patients succumbed to the deadly outbreak and a total of 2,420 patients have been infected. Of these 763 were laboratory confirmed. Cases have been reported in 7 districts in Angola.[1]

African Transmission

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It has also been confirmed that the disease spread to the Democratic Republic of Congo(DRC) and Kenya. Some of these cases have been link back to the Angolan outbreak.[11]

On 22 March 2016 the National IHR Focal Point in the DRC informed the WHO of 453 possiple cases of yellow fever and 45 deaths. A further investigation by a virologist from Cameroon confirmed a high presence of the Aedes aegypti mosquito larvae and the possibility of increased local transmission of the disease in the country. By 23 April the DRC declared an outbreak of yellow fewer.[2]

On 20 May 2016 the WHO confirmed 44 laboratory cases and five possible cases in the DRC and two cases in Kenya.The WHO is also following up the possibility that 8 of these cases were locally transmitted in the DRC. The cases are mostly in the capital Kinshasa and the Kongo province. Of those infected 42 cases have been link to recent travel to Angola.[1]

In Kenya the two case were also returning workers from Luanda. The WHO was informed of the cases by the National IHR Focal Point of Kenya by 18 March 2016. Both patient presented with symptoms before traveling back to Kenya and subsequently sought medical attention. Of the two patients one passed away from multi organ failure in hospital.[3]

International Transmission

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The first case to be reported outside of Africa was reported on 13 March 2016 by the National IHR Focal Point of China. The index case was a Chinese citizen, working in Angola, who fell ill after his return to China.[12] By 20 May the WHO confirmed 11 imported cases of the virus in China. This transmission is linked to the Angolan outbreak.[11][1]

Separate Ugandan outbreak

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On 8 April 2016 the WHO National IHR Focal Point of Uganda also reported a second outbreak in Uganda in the Masaka district, south of Kampala.[13] The outbreak spread to three provinces namely Masaka, Rukungiri and Kalangala. This outbreak is not linked to the Angolan outbreak. A total of up to 60 cases have been reported of which 7 cases are laboratory confirmed.[1][14] In mid April the WHO reported 21 deaths due to the disease.[15]

Responses

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On 19 May 2016 Bruce Aylward from the WHO stated that 11.7 million doses of vaccines have been sent to Angola in an effort to stem the spread of the disease. The WHO plans to sent an additional 2.2 million doses of the vaccine the DRC to prevent the disease from spreading.[10] The WHO have warned that there are currently only 5 million dosage of the vaccine in stockpile but efforts are on the way to increase this to 7 million by end May 2016 and a further increase of the stockpile to 17 million by end August 2016.[10] To date 7 million people have been vaccinated in Angola. The WHO have issued the international alert due to the low stockpiles of vaccines and the fear that it may spread to neighboring countries.[14][10] The WHO highlighted a particular concern to the spread of this disease given the fact that despite vaccination the disease continues to spread and in densely populated areas.[1]

Leading the effort to prevent the spread of the disease the National Red Cross societies in Angola, DRC and Uganda identified breeding grounds for mosquitoes and efforts are in place to eliminate these areas. Public awareness of the disease as to how to prevent the disease are also being raised.[11]

Prevention

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Main article: Yellow fever

Personal prevention of yellow fever includes vaccination, as well as avoidance of mosquito bites in areas where yellow fever is endemic. Institutional measures for prevention of yellow fever include vaccination programmes and measures of controlling mosquitoes. Programmes for distribution of mosquito nets for use in homes are providing reductions in cases of both malaria and yellow fever.

Vaccination

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Main article: Yellow fever vaccine

Vaccination is recommended for those traveling to affected areas, because non-native people tend to suffer more severe illness when infected. Protection begins by the 10th day after vaccine administration in 95% of people,[16] and lasts for at least 10 years. About 81% of people are still immune after 30 years. The attenuated live vaccine stem 17D was developed in 1937 by Max Theiler.[16] The World Health Organization (WHO) recommends routine vaccinations for people living in affected areas between the ninth and 12th month after birth.[7] Up to one in four people experience fever, aches, and local soreness and redness at the site of injection.[17]

In 2013, the WHO stated, "a single dose of vaccination is sufficient to confer life-long immunity against yellow fever disease."[18]

Treatment

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Main article: Yellow fever

As for other flavivirus infections, no cure is known for yellow fever. Hospitalization is advisable and intensive care may be necessary because of rapid deterioration in some cases. Different methods for acute treatment of the disease have been shown to not be very successful; passive immunisation after emergence of symptoms is probably without effect. Ribavirin and other antiviral drugs, as well as treatment with interferons, do not have a positive effect in patients.[19] A symptomatic treatment includes rehydration and pain relief with drugs such as paracetamol (acetaminophen in the United States). Acetylsalicylic acid (aspirin) should not be given because of its anticoagulant effect, which can be devastating in the case of internal bleeding that can occur with yellow fever.[19] In severe epidemics, the mortality may exceed 50%.[20]

References

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  1. ^ a b c d e f g h i j "Yellow fever situation report". WHO. 20 May 2016. Retrieved 21 May 2016.
  2. ^ a b "Yellow fever – Democratic Republic of the Congo". WHO. 2 May 2016. Retrieved 21 May 2016.
  3. ^ a b "Yellow Fever – Kenya". WHO. 6 April 2016. Retrieved 21 May 2016.
  4. ^ "Meeting of the Emergency Committee under the International Health Regulations (2005) concerning Yellow Fever". World Health Organization. 19 May 2016. Retrieved 21 May 2016.
  5. ^ a b c d e f g h i j k l m n "Yellow fever Fact sheet N°100". World Health Organization. May 2013. Retrieved 23 February 2014.
  6. ^ Lindenbach, B. D.; et al. (2007). "Flaviviridae: The Viruses and Their Replication". In Knipe, D. M. and P. M. Howley. (eds.) (ed.). Fields Virology (5th ed.). Philadelphia, PA: Lippincott Williams & Wilkins. p. 1101. ISBN 0-7817606-0-7. {{cite book}}: |editor= has generic name (help)
  7. ^ a b Tolle MA (April 2009). "Mosquito-borne diseases". Curr Probl Pediatr Adolesc Health Care. 39 (4): 97–140. doi:10.1016/j.cppeds.2009.01.001. PMID 19327647.
  8. ^ "Frequently Asked Questions About Yellow Fever". CDC. 21 August 2015. Retrieved 18 March 2016.
  9. ^ "Yellow fever – Angola". WHO. 13 April 2016. Retrieved 21 May 2016.
  10. ^ a b c d e "Yellow fever outbreak 'serious' but not global health crisis: WHO". Yahoo News. 19 May 2016. Retrieved 21 May 2016.
  11. ^ a b c "Angola yellow fever outbreak could spark 'global crisis'". News 24. 19 May 2016. Retrieved 21 May 2016.
  12. ^ "Yellow Fever – China". WHO. 29 March 2016. Retrieved 21 May 2016.
  13. ^ "Yellow fever – Uganda". WHO. 2 May 2016. Retrieved 21 May 2016.
  14. ^ a b "Angola: Deadly Yellow Fever Is Spreading Unabated". AllAfrica. 20 May 2016. Retrieved 21 May 2016.
  15. ^ "YELLOW FEVER OUTBREAK KILLS 21 IN CONGO". EYEWITNESS NEWS. 13 April 2016. Retrieved 21 May 2016.
  16. ^ a b Barrett AD, Teuwen DE (June 2009). "Yellow fever vaccine – how does it work and why do rare cases of serious adverse events take place?". Current Opinion in Immunology. 21 (3): 308–13. doi:10.1016/j.coi.2009.05.018. PMID 19520559.
  17. ^ Yellow Fever Vaccine Information Statement. Centers for Disease Control and Prevention. March 30, 2011.
  18. ^ WHO | Yellow fever vaccination booster not needed. Who.int (2013-05-17). Retrieved on 2014-05-12.
  19. ^ a b Monath TP (April 2008). "Treatment of yellow fever". Antiviral Res. 78 (1): 116–24. doi:10.1016/j.antiviral.2007.10.009. PMID 18061688.
  20. ^ Tomori O (2004). "Yellow fever: the recurring plague". Crit Rev Clin Lab Sci. 41 (4): 391–427. doi:10.1080/10408360490497474. PMID 15487593.


* Category:Flaviviruses Category:Insect-borne diseases

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