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2014年西非埃博拉病毒爆发或与太阳黑子活动有关
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An ever-present threat of a major new influenza pandemic of devastating proportions haunts us, and despite
diligent monitoring of circulating viruses has been impossible to predict. On a more local scale outbreaks of Ebola
Hemorrhagic Fever (EHF) in West Africa have posed a serious public health threat because of its high fatality risk.
Research on the environmental factors underlying both EHF and influenza epidemiology may provide useful insights
into the occurrence of future pandemic outbreaks. This study suggests that sunspot activity in extremum or ± one
year was associated with influenza pandemics and severe EHF outbreaks in Africa from 1976 to 2014. Potential
mechanisms by which sunspot activity may influence viral outbreaks are discussed. Current and future surveillance
efforts should be supported to construct a comprehensive early warning system involving virus monitoring and
epidemioilogy on the ground, sunspot activity as well as stratospheric sampling for forecasting future pandemics.
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为什么埃博拉爆发与太阳黑子活动有关？
Multiple factors may contribute to EHF outbreaks in humans in the era of globalization. These diverse factors include environmental destruction, widespread deforestation,bushmeat consumption, climate change, economic underdevelopment, lack ofmedical resources, microbial genetic mutation, and so on.1,2 However, severe Ebola outbreaks onlyemerged in some special years, so some special unusual factors must haveemerged and played decisive roles on the occurrence of Ebola outbreak in those years.
This study showedthat sunspot activityin extremum or ±one year was likely to be one of the most important factors inthe development of severe Ebola outbreaks.Sunspot numbers are strongly correlated with solar activity, such as X-rayflares and total irradiance of the sun. Increased numbers of solar flares andcoronal mass ejections produce numerous high-energy solar particles during thesolar maximum period.3,4 Furthermore, cosmic rays reach amaximum intensity when the sun is least active and fall at minimum intensityduring the solar maximum period.3 Our resultsalso indicated that the coefficientof correlation between the relative sunspot number and cosmic ray data was−0.90. Point mutations, gene recombination,and gene reassortment are thought to be the three basic mechanisms of viralemergence.5Solar radiation and cosmic rays are physical mutagens of naturalpoint mutation, and can lead to the emergence of severe Ebola outbreaks.Recombination and reassortment occur at highly variable frequencies in viruseswith RNA as their genetic material. Multiplicity reactivation and crossreactivation have been proven to be important mechanisms of geneticrecombination. Reactivation has been observed in influenza viruses irradiatedby all types of radiations, such as ultraviolet light and gamma ray, inlaboratories during the 1950s to the 1960s. The Ebola virus is a non-segmentedRNA virus, and high mutation rates allow RNA viruses to cross species barriersand adapt to new hosts. The viral strains involved in all Ebola outbreaks carrydistinctive genetic variations, and genetic mutations may be a crucial factor influencingthe severity of Ebola outbreaks. For example, the human outbreaks in Gabon andthe Republic of Congo during 2001 to 2004 consisted of multiple simultaneousepidemics caused by different viral strains.6A related study revealed that the Zaire Ebola virus isolated from wild apes inthe Gabon/Congo region were recombinants, and the recombination event probablyoccurred between 1996 and 2001 and resulted in a group of recombinant virusesthat were responsible for a series of outbreaks in 2001–2003.7 Genetic data also suggested that the current Ebola outbreak inSierra Leone was caused by a newstrain evolving from two viral lineages from neighboring Guinea, and it was caused by a single interaction between humans and aviral reservoir in animals.8,9The viral genome is changing at very rapid rates, and itsunique mutations might influence the severity of the 2014 outbreak.9
Sunspot activity in the maximum or minimumphase can significantly impact the Earth’s climate, thereby causing extremeclimate events, such as drought, hurricane, and severe cold.10–13 The International Food Policy ResearchInstitute released a report in 2013, which stated that climate change leads toseasonal droughts, high winds, thunderstorms, landslides, heat waves, floods,and changing rainfall patterns in Sierra Leone. Increasingly frequent extremeweather events can alter the migration, stopover time, fitness, andinterspecies mixing of migratory animals. Regarding the current outbreak, thefirst case of EHF in Guinea occurred in December 2013 at the beginning of thedrought season; this finding was consistent with observations from othercountries that outbreaks often begin during the transition from the rainyseason to drought season.6, 14–17 Sharply drier conditions at the end ofrainy seasons have been thought to be one triggering event of EHF outbreaks.15 Strong scientific evidence points to the fruit bats, which are present in large parts of WestAfrica as the host species for the Ebola virus.18These bats are highly mobile andseasonally nomadic in response to local food availability, and they probablyshift habitats or territories because of changes in food availability orhabitat suitability that may be influenced by drought weather. These bats maymigrate from the depths of the rainforest and live closer to local villages inpursuit of food, sometimes amongst human populations. Fruit bats, a majorsource of protein, are widely eaten in rural West Africa. Presumably, localvillagers might have contacted with bats or their secretions and then becameinfected with the Ebola virus through various human activities, such as huntingor handling of Ebola-infected bats. Dry conditions can also cause fires andrainforest fragmentation. The latter increases the likelihood that bats willattempt to find other places to live. A prior outbreak investigation pointed tothe coincident timing of an annual influx of migratory fruit bats in theDemocratic Republic of Congo and the start of human Ebola outbreaks in localvillages during 2007, and the first human case was linked to migratory batsthat stayed in the area during the migratory season.19 In addition, the new viral sequences alsorevealed that last year’s outbreak likely spread from Middle Africa throughfruit bats within the last decade.20 The lack of food resources caused bydroughts can also increase interspecies contacts to compete for limited foodsources available between the fruit bats and intermediate hosts, includingchimpanzees and other primates, and these contacts may facilitate genetic recombinationof any circulating Ebola virus in different species by sunspot activity.Finally, some Ebola viruses have successfully acquired the ability to spreadfrom animal hosts to humans, triggering the outbreaks in humans.
Predictingthe behavior of a sunspot cycle is fairly reliable once a cycle has reachedabout three years after the minimum sunspot number occurs.21 Thus, we can use the sunspot data toprovide early warning information for epidemiological and virologicalsurveillance of future severe EHF outbreaks. In the future, a comprehensive earlywarning system, including sunspot activity, climatic factors, fruit batmigration, animal mortality, and serological and virological surveillance,should be established so that severe EHF outbreaks can be detected as early aspossible.
References
1. Bausch DG, Schwarz L (2014) Outbreak of ebola virusdisease in Guinea: where ecology meets economy. PLoS Negl Trop Dis8:e3056.
2. Ng S, Basta NE, Cowling BJ. (2014)Association betweentemperature, humidity and ebolavirus disease outbreaks in Africa, 1976 to 2014.Euro surveillance 19:1–11.
3. O'Sullivan D. (2007) Exposure to galactic cosmicradiation and solar energetic particles. Radiat Prot Dosim 125:407–411.
4.Hathaway DH, Wilson RM. (2004)What the sunspot record tells us about space climate. Solar Phys 224:5–19.
5. Domingo E. (2010)Mechanisms of viral emergence. VetRes 41:38.
6. LeroyEM, et al. (2004) Multiple Ebola virus transmission events and rapid decline of centralAfrican wildlife. Science 303:387–390.
7.Wittmann TJ, et al. (2007) Isolates of Zaire ebolavirus from wild apes reveal genetic lineage andrecombinants. Proc Natl Acad Sci USA104:17123–17127.
8. Baize S, et al. (2014)Emergence of Zaire Ebolavirus disease in Guinea. N Engl J Med 371:1418–1425.
9. Gire SK, et al. (2014) Genomic surveillanceelucidates Ebola virus origin and transmission during the 2014 outbreak. Science 345:1369–1372.
10. Ineson S, et al. (2011)Solar forcing of winter climate variabilityin the Northern Hemisphere.Nat Geosci 4:753–757.
11. Stager JC, Ryves D, Cumming BF, Meeker LD, Beer J (2005)Solar variability and the levels of LakeVictoria, East Africa, during the last millennium.J Paleolimnol33:243–251.
12. Stager JC, Ruzmaikin A, Conway D, Verburg P,Mason PJ (2007) Sunspots, El Niño, and the levels of Lake Victoria, East Africa.J Geophys Res112:15.
13. Gachari F, Mulati DM,Mutuku JN.(2014)Sunspot numbers: Implications on EasternAfrican rainfall. S. Afr. j. sci 110:1–5.
14. Lahm SA, Kombila M, Swanepoel R, Barnes RF. (2007)Morbidity and mortality ofwild animals in relation to outbreaks of Ebola haemorrhagic fever in Gabon,1994-2003. Trans R Soc Trop Med Hyg101:64–78.
15. Bermejo M, et al. (2006)Ebola outbreak killed 5000gorillas. Science 314:1564.
16. Pinzon JE, et al. (2004) Trigger events:enviroclimatic coupling of Ebola hemorrhagic fever outbreaks. Am J Trop Med Hyg 71:664–674.
18. Leroy EM, et al. Fruit bats as reservoirs ofEbola virus. Nature 2005;438:575-576.
19. Leroy EM, et al. (2009)Human Ebola outbreak resultingfrom direct exposure to fruit bats in Luebo, Democratic Republic of Congo,2007. Vector Borne Zoonotic Dis9:723–728.
20. Vogel G (2014) Genomes reveal start ofEbola outbreak. Science 345:989-990.
21. Hathaway DH, Wilson MR, Reichmann JE (1999)A synthesis of solar cycle predictiontechniques. J Geophys Res 104:22375–22388.
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