Review of the role of food and the food system in the transmission and spread of ebola virus
Summary of research1
Location: West Africa
What we know: The current outbreak of ebola virus disease (EVD) centred in West Africa is the largest in history. The full role of food in EVD spread is not well studied.
What this article adds: A recent literature review investigated how food may transmit ebola viruses and how the food system contributes to EVD outbreak and spread. Harvesting and consumption of ‘bushmeat’ is a high-risk activity; food insecurity may lead to more bush-meat harvesting and increase outbreak risk. There is evidence linking ebola to pigs; an outbreak amongst swine would have economic and potential outbreak implications. There is no published literature on the risk of plant food products transferring ebola virus; this would have implications for local and global food systems. Food and the food system may be more implicated in ebola virus transmission than expected; further research is urgently needed.
The current outbreak of ebola virus disease (EVD) centred in West Africa is the largest in history, with nearly ten times more individuals contracting the disease than all previous outbreaks combined. Active transmission was occurring in three countries (Guinea, Liberia and Sierra Leone), and seven additional countries experienced isolated cases. With food systems an integral part of a globalised world, this article investigates the connections that exist between EVD outbreaks and food, describes what is currently known about how food can transmit ebola viruses, and how the food system contributes to EVD outbreak and spread.
The details of human-to-human and zoonotic ebola virus transmission have justifiably received the largest share of research attention and much information exists on these topics. However, although food processing – in the form of slaughtering and preparing wildlife for consumption (referred to as bushmeat) – has been implicated in EVD outbreaks, the full role of food in EVD spread is poorly understood and has been little studied.
The authors conducted a literature review using keyword searches in online databases to assess the current state of knowledge regarding how food can or may transmit ebola viruses and how the food system contributes to EVD outbreak and spread. The authors categorised results of the search into various topics, outlined below. Figure 1 outlines the ways in which food is connected to EVD outbreaks.
Figure 1: Ebola virus, EVD outbreaks and food
Animal food products and ebola virus transmission
Although the exact nature of animal-to-human transmission of ebola viruses is not often known, the harvesting of bushmeat (including rodents, bats, shrews, duikers and non-human primates) is directly related to ebola virus transmission. The hunting and butchering of bushmeat exposes humans to blood and other fluids of potentially infected animals. In 2014, the Centers for Disease Control and Prevention (CDC) noted that human ebola virus infections have been associated with handling and eating infected animals, with evidence of previous outbreaks of EVD beginning after humans handled infected carcasses of primates and duikers (Rouquet et al, 2005).
While bushmeat harvesting and consumption is a proven high-risk activity, it is an important source of cash income and a food source in West Africa, particularly during times of economic hardship (Leroy et al, 2009). The public health risk from zoonotic pathogens entering countries via infected bushmeat is estimated to be substantial due to widespread smuggling, including into the US and Europe, where demand is high, although exact figures and associated risk are very difficult to establish (European Food Safety Authority, 2014).
It has been hypothesized that livestock could be a possible ebola virus reservoir, but studies to date on horses, sheep, goats, cattle and chickens have been inconclusive. There is, however, evidence linking ebola viruses and pigs, specifically the ‘Reston virus’ (an ebola virus not pathogenic to humans) (e.g. Pan et al, 2014). Recent studies have shown that swine can become infected with ebola virus, develop clinical symptoms and transmit the virus to healthy pigs (Kobinger et al, 2011). In 2012, Weingartl et al determined that infected pigs could transmit the virus to non-human primates. Additional studies in Uganda and the Democratic Republic of the Congo (DRC) have suggested that EVD outbreaks have occurred in areas with high densities of swine (Weingartl et al, 2013) or following large mortality events of swine (Katayi, 2014). If swine are contributing to EVD aetiology, it is a cause for concern in sub-Saharan Africa where swine production is growing, often in areas near to the habitat of bats, who are increasingly being identified as the key ebola virus reservoir (Olival & Hayman, 2014).
Plant food products and ebola virus transmission
Consumption of contaminated plant food products
There is concern that ebola virus may be transmitted to humans via bat saliva or faeces on fruit such as mangoes or guava. This mechanism has been experimentally verified for the Marburg virus (a member of the Filoviridae family with ebola viruses) (Amman et al, 2015) and the Nipah virus, whose reservoir is also in fruit bats (Luby et al, 2009). It is plausible, therefore, that this mode of transmission may either start or aid the spread of EVD during outbreaks, although the current lack of knowledge and data make it impossible to quantify the risk (European Food Safety Authority, 2014).
Fomite transmission involving plant food products
Fomite transmission (transmission of infectious disease by objects) of EVD is possible, although the risks during food harvesting and production are not well understood. There is no published literature on the risk of plant food products serving as fomites in ebola virus transmission, although other viruses are known to be transmitted via food contaminated by food preparers that can subsequently infect individuals after they consume or handle the food, such as hepatitis A (Boone & Gerba, 2007) and Lassa fever, which is closely related to EVD (WHO, 2015).
Fomite transmission depends on virus survival in the environment and studies have shown that the ebola virus is able to survive outside the host (especially at lower temperatures) between several days and over three weeks (Sagripanti et al, 2010). It should be noted that fomite transmission involving raw food products has not been documented and warrants further research.
Other ebola virus and food considerations
Pubic health consequences of landscape changes caused by food production
Food systems may indirectly contribute to EVD transmission, particularly the consequences of environmental conditions such as deforestation that lead to increased human interaction with wildlife species that carry ebola viruses (Muyembe-Tamfum et al, 2012). Experts have begun exploring the connections between the latest EVD outbreak and ecological disruptions, including those related to agriculture (Bausch & Schwarz, 2014).
Additional swine concerns
This article suggests that an EVD outbreak among farmed swine would pose a number of concerns, including: significant animal loss with severe economic consequences; fear and panic among consumers regarding EVD as a food-borne illness leading to severe market disruption; and the considerable risk of ebola virus becoming endemic in wild pigs, which are known to carry numerous human disease-causing pathogens already (Bevins et al, 2014). There is an additional concern that swine could potentially serve as sites for new, more harmful strains of the virus to arise (MacNeil & Rollin, 2012).
Harvest, transport and trade
If ebola viruses do remain infectious on fomites for several weeks in a real-world environment, there are implications for the global food system from harvest to the end-consumer which could have major implications for the economies and labour forces of affected nations. A scenario is described in the paper where potential transmission involves an enclosed, refrigerated shipping container on a cargo ship transporting food products and the possible routes of contamination.
Food insecurity in West Africa
The EVD outbreak in West Africa has led to increases in food insecurity in the three affected countries. The authors summarise a UN Food and Agriculture Organization report from September 2014 of severe disruptions in food availability due to: quarantine-imposed travel restrictions on sellers and consumers; panic buying; dramatic price increases; and reduced food production and harvests (including income from cash-cropping) caused by farm labour shortages and restrictions on movement. Increasing food insecurity could potentially lead to more bushmeat harvesting and associated risks of further outbreaks.
Conclusions and research needs
While much remains unknown about ebola virus transmission (Osterholm et al, 2015), this literature reveals surprising preliminary evidence that food and the food system may be more implicated in ebola virus transmission than expected. Further research is urgently needed.
1 Mann E, Streng S, Bergeron J, Kircher A, 2015. A Review of the Role of Food and the Food System in the Transmission and Spread of Ebolavirus. PLoS Neg lTrop Dis 9(12):e0004160. doi:10.1371/journal.pntd.0004160
Amman BR, Jones ME, Sealy TK, Uebelhoer LS, Schuh AJ, Bird BH, et al. Oral shedding of Marburg virus in experimentally infected Egyptian fruit bats (Rousettus Aegyptiacus). J Wildl Dis. 2015; 51 (1):113–24. doi: 10.7589/2014-08-198 PMID:25375951 PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.0004160 December 3, 2015 9 / 11
Bausch DG, Schwarz L. Outbreak of Ebola Virus Disease in Guinea: Where Ecology Meets Economy. PLoS Negl Trop Dis. 2014; 8: e3056. doi: 10.1371/journal.pntd.0003056 PMID: 25079231 PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.0004160 December 3, 2015 10 / 11
Bevins SN, Pedersen K, Lutman MW, Gidlewski T, Deliberto TJ. Consequences Associated with the Recent Range Expansion of Nonnative Feral Swine. BioScience. 2014; 64: 291–299. doi: 10.1093/biosci/biu015
Boone SA & Gerba CP. Significance of Fomites in the Spread of Respiratory and Enteric Viral Disease. Appl Environ Microbiol. 2007; 73: 1687–1696. doi: 10.1128/AEM.02051-06 PMID: 17220247
Chaber A-L, Allebone-Webb S, Lignereux Y, Cunningham AA, Marcus Rowcliffe J. The scale of illegal meat importation from Africa to Europe via Paris. Conserv Lett. 2010; 3: 317-321. doi: 10.1111/j.1755-263X.2010.00121.x
European Food Safety Authority. An update on the risk of transmission of Ebola virus (EBOV) via the food chain Part 2. EFSA J. 2015; 13: 4042-4058. doi: 10.2903/j.efsa.2015.4042
Katayi, K. Ebola sleuths scour DR Congo jungle for source of outbreak (L’Agence France-Press). Yahoo News. 23 Oct 2014. Accessed 3 Aug 2015.
Kobinger GP, Leung A, Neufeld J, Richardson JS, Falzarano D, Smith G, et al. Replication, Pathogenicity, Shedding, and Transmission of Zaire ebolavirus in Pigs. J Infect Dis. 2011; 204(2):200-8. doi: 10.1093/infdis/jir077 PMID: 21571728
Leroy EM, Epelboin A, Mondonge V, Pourrut X, Gonzalez J-P, Muyembe-Tamfum J-J, et al. Human Ebola Outbreak Resulting from Direct Exposure to Fruit Bats in Luebo, Democratic Republic of Congo, 2007. Vector-Borne Zoonotic Dis. 2009; 9: 723-728. doi: 10.1089/vbz.2008.0167 PMID: 19323614
Luby SP, Gurley ES, Hossain MJ. Transmission of human infection with Nipah virus. Clin Infect Dis Off Publ Infect Dis Soc Am. 2009; 49: 1743–1748. doi: 10.1086/647951
MacNeil A & Rollin PE. Ebola and Marburg Hemorrhagic Fevers: Neglected Tropical Diseases? PLoS Negl Trop Dis. 2012; 6: e1546. doi: 10.1371/journal.pntd.0001546 PMID: 22761967
Muyembe-Tamfum JJ, Mulangu S, Masumu J, Kayembe JM, Kemp A, Paweska JT. Ebola virus outbreaks in Africa: past and present. Onderstepoort J Vet Res. 2012; 79: 451. doi: 10.4102/ojvr.v79i2.451 PMID: 23327370
Olival KJ, Hayman DTS. Filoviruses in Bats: Current Knowledge and Future Directions. Viruses. 2014; 6: 1759–1788. doi: 10.3390/v6041759 PMID: 24747773
Osterholm MT, Moore KA, Kelley NS, Brosseau LM, Wong G, Murphy FA, et al. Transmission of Ebola Viruses: What We Know and What We Do Not Know. mBio. 2015; 6: e00137–15. doi: 10.1128/mBio.00137-15 PMID: 25698835
Pan Y, Zhang W, Cui L, Hua X, Wang M, Zeng Q. Reston virus in domestic pigs in China. Arch Virol. 2014; 159: 1129–1132. doi: 10.1007/s00705-012-1477-6 PMID: 22996641
Rouquet P, Froment J-M, Bermejo M, Kilbourn A, KareshW, Reed P, et al. Wild animal mortality monitoring and human Ebola outbreaks, Gabon and Republic of Congo, 2001-2003. Emerg Infect Dis. 2005; 11: 283–290. doi: 10.3201/eid1102.040533 PMID: 15752448
Sagripanti J-L, Rom AM & Holland, LE. Persistence in darkness of virulent alphaviruses, Ebola virus, and Lassa virus deposited on solid surfaces. Arch Virol. 2010; 155: 2035–2039. doi: 10.1007/s00705-010-0791-0 PMID: 20842393
Weingartl HM, Embury-Hyatt C, Nfon C, Leung A, Smith G, Kobinger G. Transmission of Ebola virus from pigs to non-human primates. Sci Rep. 2012; 2: 811. doi: 10.1038/srep00811 PMID: 23155478
Weingartl HM, Nfon C, Kobinger G. Review of Ebola virus infections in domestic animals. Dev Biol Basel. 2013; 135: 211–218. doi: 10.1159/000178495 PMID: 23689899
WHO. Lassa fever. WHO [Internet]. 2015 [cited 23 Jul 2015].
More like this
Dear ENN, If there is one thing that we have learnt from the current Ebola virus disease (EVD) outbreak it is that regardless of infection status, Ebola comes bringing bad...
Posted on behalf of Fabienne Rousseau, ACF I have a question related to infant feeding in the context of the Ebola outbreak in West Africa. Our teams are engaged...
FEX: Experiences of the Sustainable Nutrition and Agriculture Promotion (SNAP) programme in the Ebola response in Sierra Leone
By Sibida George and Georgia Beans Sibida George is Team Leader with International Medical Corps/ SNAP and is based in Sierra Leone. Georgia Beans is the Chief Of Party with...
Research snapshot This Q&A with Peter Salama, Executive Director of the World Health Organization (WHO) Health Emergencies Programme, explores how the new initiative is...
en-net: What should be the nutritional support to adult patients with Ebola Virus Disease (EVD) in treatment centres in West Africa?
Dear experts, I would appreciate your help in this. I drafted the following text but you might have ideas and other suggestions. Please help me on this one... This question...
FEX: En-net update
By Tamsin Walters, en-net moderator Over the past four months1, 32 questions have been posted on en-net, generating 69 responses. Two upcoming trainings have been advertised...
In 2014, WHO launched interim guidelines on Nutritional care of children and adults with Ebola Virus Disease. I would like to know whether...
Resource: WHO/UNICEF/WFP Interim guideline: Nutritional Care of Children and Adults with Ebola Virus Disease in Treatment Centres
This interim guideline provides recommendations on nutritional support to adults and paediatric patients in Ebola treatment unit (ETUs). It highlights the key clinical problems...
Hi everyone, I was wondering if there was any definitive information on how long someone / their body fluids are infectious for once their blood tests come back clear of Ebola...
FEX: Research snapshots
Factors influencing pastoral and agropastoral household vulnerability to food insecurity in Kenya Kenya has a population of more than 38 million, 10% of whom are classified as...
Summary of research1 Location: Global What we know: Optimising SAM management is an important strategy for reducing malnutrition-related mortality. What this article adds: A...
Research snapshot1 Undernutrition increases the frequency, severity and fatality of many infections, including tuberculosis (TB), while infections, in turn, worsen...
What are the risks of hepatitis virus infection through breastfeeding? And prevention method for Hepatitis mothers and any medical prophylaxis for breastfeeding mother? A...
We are looking for: AN EXPERT EPIDEMIOLOGIST Country: Based in LIBERIA - Monrovia (Montserrado County with frequent trip to Bomi County) on Ebola emergency and base opening...
Summary of research1 Location: Global What we know: Rapid data sharing is critical for decision-makers in public health emergencies, but may prejudice subsequent journal...
By Tanya Doherty (pictured), Mickey Chopra and Mike Colvin Tanya is currently a senior scientist at the Health Systems Trust and Medical Research Council in Capetown, South...
FEX: Simplifying the response to childhood malnutrition: MSF’s experience with MUAC-based (and oedema) programming
By Kevin P.Q. Phelan, Candelaria Lanusse, Saskia van der Kam, Pascale Delchevalerie, Nathalie Avril and Kerstin Hanson Kevin P.Q. Phelan was the Nutrition Working Group Leader...
Summary of research* Location: Global What we know: Diarrhoea is commonly associated with SAM; carbohydrate malabsorption may be a contributing factor. What this article...
FEX: Complementary food hygiene: An overlooked opportunity in the WASH, nutrition and health sectors
Summary of research1 Location: Global What we know: Poor food hygiene may account for a substantial proportion of diarrhoeal diseases and contribute to malnutrition among...
en-net: Medair seeks Health Manager (s) - (Supervising Nurse or Doctor) for its programme in Sierra Leone
Role and Responsibilities Contribute to the mitigation of the overall ebola outbreak through the provision of quality health services to suspected and confirmed ebola...
Reference this page
Review of the role of food and the food system in the transmission and spread of ebola virus. Field Exchange 52, June 2016. p20. www.ennonline.net/fex/52/foodsystemebolavirus