Eradicating Ebola1.docx

1、Eradicating Ebola1Eradicating EbolaAbstractEbola virus is a type of virus which has posed a large scale of epidemic situation due to its extreme infectivity. To control the epidemic situation and even eliminate the virus, we initiated our investigation with samples selected in typical epidemic areas

2、, including Guinea, Sierra Leone and Liberia. Additionally, we formulated three elementary mathematical models for convenience in medicine supplement, medicine production and medicine delivery.Given fixed epidemic areas, we established our first model based on SIR model (transmission model of infect

3、ious disease), to address problems of medicine supplement. For simplicity, we ruled out other confounding factors such as birth, natural death and divided local residents into three categories. Then we analyzed the relations of the quantity proportion among these groups. Utilizing algorithms of SIR

4、model, we carried out medicine supplement in numerous areas.In terms of medicine production, the major issues we were confronted with were expense of production and expense of storage. Through discussion, we concluded that both two types of expenses are directly proportional to the amount of medicin

5、e produced, and thus established the production scheme model. After compromising medicine demand and the actual production rate, we optimized the production configuration at the least expense.On top of issues of supplement and production scheme, to enhance the efficiency of controlling epidemic situ

6、ation, we took into account the delivery scheme from two aspects: the amount of medicine demanded and the most efficient route for delivery. We considered these two problems according to the number as well as the proportion of patients and finally established the medicine delivery scheme model. Afte

7、r arranging medicine storage, we achieved a strategic plan for medicine delivery.Eventually, to examine the effectiveness of our models, we compared these data to the results on the Internet. And the comparison indicates that our models can be applied in practical utility.In brief, we did comprehens

8、ive analysis and adjustment on the three models and reached optimal configuration for the issues. Finally we prepared a 1-2 page letter that explains our results and mathematical models that staffs in WHO can comprehend.Keywords: medicine supplement, medicine production scheme and medicine delivery

9、scheme, elementary modelContentsAbstract1Contents2.Introduction31.1Background21.2Genus Ebola virus21.3Source of human infection21.4Evidence of human-to-human transmission21.5Signs and symptoms21.6Diagnosis and treatments21.7Ebola virus breaking out in West Africa2.Analysis for the issues3.The basic

10、assumptions3.Nomenclature3.Our model 135.1 Model analysis25.2 Model establishing25.3 Model solution25.4 Test of models application2.Our model 13.IntroductionEbola virus,a particularly fatal virus which leads to Ebola haemorrhagic fever, first appeared in 1976 with two simultaneous outbreaks in Nzara

11、, Sudan, and in Yambuku, Democratic Republic of Congo (formerly Zaire) has raised great concern about medical field since then. Ebola virus is contagious both to mankind and non-human primates. Its symptoms include fever, shock and multiple organ failure which exhaust people to death. So far, accord

12、ing to the data given by World Health Organization (WHO), the fatality rate of Ebola virus has been recorded to be as high as ninety percent.1.1 BackgroundThe name Ebola originated from a river in the north of Democratic Republic of Congo. In 1976, a scarce virus appeared there, attacking fifty-five

13、 villages nearby and caused thousands of death. Ebola was taken as the name this severe virus ever since. Three years later, Ebola came back and swept Sudan. After these two cruel plagues, Ebola vanished for fifteen years.1.2 Genus Ebola virusGenus Ebola virus is one of three members of the Filoviri

14、dae family (filovirus), along with genus Marburg virusand genusCueva virus. So far human has specified five distinct species: Zaire Ebola virus (EBOV) Bundibugyo Ebola virus (BDBV) Sudan Ebola virus (SUDV) Tai Forest Ebola virus (TAFV) Reston Ebola virus (RESTV)BDBV, EBOV, and SUDV have been related

15、 to large Ebola virus outbreaks in Africa, whereas RESTV and TAFV have not.Those species differ in pathology. EBOV and SUDV are founded fatal both to mankind and non-human primates, while BDBV has no obvious influence on mankind but is still fatal to non-human primates. The RESTV species, found in P

16、hilippines and the Peoples Republic of China, can infect humans, but no illness or death in humans from this species has been reported to date(death?).1.3 Source of human infectionFruit bats are suspected as the natural host for Ebola virus. According to the reports from Cable News Network (CNN) and

17、 Daily Mail, the Ebola virus disease recently spreading in West Africa may outbreak from 2-year-old child bitten by a fruit bat. They said, the child was bitten by a fruit bat and then died four days later, on 6 December 2013. After his death, his mother initiated bleeding symptom and died on 13 Dec

18、ember 2013. Then it came to those who had attended their funeral. After that were the villages nearby. Thereafter, the plague expanded to the whole West Africa. Non-human primates have been considered as a source of Ebola virus. However, a decade ago they were substantiated to be an accidental host

19、just like human beings.1.4 Evidence of human-to-human transmissionEbola virus infests wild animals. Via close contact with infected animals such as the blood, secretions and other bodily fluids, Ebola virus is brought into human community. And then, through direct contacts (broken skin, mucous membr

20、anes with the blood, secretions etc.) and indirect contacts (environments contaminated with fluids), Ebola virus continues its transmission among humans.And the virus equips no infectiousness during the incubation period (varying from 2to 20 days) and becomes contagious once a host presents with sym

21、ptoms.The virus remains in the semen of persons who have recovered from the disease for three months after rehabilitation.1.5 Signs and symptomsDuring the incubation period, infected persons dont feel sick until onset of symptoms.Ebola virus usually comes with sudden onset of fever, intense weakness

22、, muscle pain, headache, nausea and sore throat. Then the following symptoms like vomiting, diarrhea arise. Finally patients will die due to organ impairment.1.6 Diagnosis and treatmentsDefinitive diagnosis of EVD is made through laboratory testing because of infection risk. Laboratory findings freq

23、uently include low white blood cell and platelet counts and elevated liver enzymes.Up to now, there are no licensed Ebola vaccines but 2 potential candidates are undergoing evaluation.Early supportive care with rehydration, symptomatic treatment improves survival. There is as yet no licensed treatme

24、nt testified to annihilate the virus but a range of blood, immunological and drug therapies are under development.1.7 Ebola virusbreaking out in West AfricaEbola virus breaks out in West Africa in Feb 2015. Till now, based on the reports on Ebola from WHO, it has almost swept the whole West Africa,

25、especially in countries like Guinea, Sierra Leone and Liberia. Even distant countries such as USA, Spain and UK have been involved in this disaster. As is reported to date, Ebola has posed 22495 cases of Ebola virus disease and 8981 deaths cumulatively.Figure1. Map of Ebola cases over the worldFigur

26、e2. Distribution of Ebola case over the world.Analysisfor the issues2.1 Spots selected for experiment Ebola virus transmits endemically, and usually it is restricted in the tropical rainforests of central Africa and the steppes of southeast Africa by specific environmental conditions. Those years th

27、is kind of virus has spread from the initiate Sudan and Congo to other countries nearby such as Central African, Libya and Gabon.Nevertheless, in countries distant from Africa such as USA and Spain, cases of Ebola virus disease occur accidentally but are all attributed to import infection. To some e

28、xtent, it shows the virus transmits in specific regions. In other words, the virus transmits endemically and will not find any other area suitable for its breed because it is restricted by space. Therefore we select three countries Guinea, Sierra Leone and Liberia, where the Ebola virus cases occur

29、most frequently, as a sample.And here is a survey on populations of distinct regions in these three countries.Figure3. Population distributions of distinct regions in Guinea, Sierra Leone and LiberiaGuineaPopulationSierra LeonePopulationLiberiaPopulationG1289,000S1274,118L1276,863G2165,000S2452,095L

30、2127,076G3284,000S3549,924L383,388G482,000S4256,686L484,119G5131,000S51,345,142L51,118,241G6156,000S6418,184L6333,481G7286,000S7352,048L7462,026G8136,000S8570,283L8209,923G9421,000S9404,036L9221,693G10246,000S10151,979L1071,509G11156,000S11156,388L11102,391G12114,000S12537,864L12125,258G13160,000S13

31、387,824L1366,789G14244,000L1457,913G15167,000L15135,938G16744,000G17235,000G18188,000G19296,000G20278,000G2187,000G22124,000Total4,989,000 5,856,5713,476,608 List1. Populations of corresponding regions.The basic assumptions.Nomenclature. Medicine supplement model5.1 Model analysisWith the deterioration of Ebola disease, people in infected area demand more medicine.Thus we assume medicine quantity demanded keeps two times the quantity of infected cases (except the deaths).As for the popu