Transmission Of Ebola Virus On Animal And Humans
Abstract
Ebola virus (EBV) is a deadly virus that has resulted in a number of deaths during its outbreaks in Africa in 2014–2016 and 2018–2019. This virus causes a hemorrhagic fever like other pathogenic viruses of the Filoviridae family with high mortality rate. The Ebola virus disease (EVD) occurred in a small town near the ebola river from which it intakes its name. EVD first found in 1976 in simultaneous out breaks one is Nzara South Sudan and second one is yambuku, DRC.It can be spared to the population via wild animals and after then if a healthy individual come in contact with ebola infected person so then healthy one is also infected and this cycle runs without precaution so that a large number of population get infected. Ebola virus (EBV) belongs to the Filoviridae family and it is specialized hemorrhagic fever and it is rare but fatal illness in human. According to world health organization average rate of fatality is about 50% cases and it varied from past outbreak from 25% to 90%. This particular virus humiliate a lot cells primarily it attacks on macrophages and dendritic cells and after that primary immune system start attacking against virus by using of cytokines a lots of cytokines attacks on virus at that time it look like whirlwind, But Filoviridae family particularly lethal because it affect wide range if organs. Ebola virus can affect spleen lung and kidneys and this particular virus affect cells of these organs those cells who are helping for chemical balance and some protein which is responsible for blood clotting.EVD can be rule out if preventive community get engagement. In community must have case namely management, infection prevention, control practices patient surveillance and good laboratory practice.
Chapter One
Introduction
Background Information
Transboundary animal diseases may be defined as those epidemic diseases which are highly contagious or transmissible and have the potential for very rapid spread irrespective of national borders, causing serious socio economic and possible health consequences (FAO, 2004). They constitute only a small minority of the infectious diseases that affect livestock but are dreaded for their suddenness, acuteness, and the wide spread nature of the losses they can produce (Chris et al.,1999).
There are two major types of transboundary animal diseases- the emerging diseases and the zoonoses (OIE, 2012). According to Morens and Fauci 2013, Emerging diseases can be classified into newly emerging diseases and reemerging diseases. Reemerging and newly emerging diseases can be defined respectively as those diseases that are able to expand their epidemiological spectrum appearing in new geographical area, affecting new susceptible species which is usually associated with the acquisition of new genes by an existing microbe; and referring to a completely unknown pathogen which is detected for the first time. Newly emerging infectious agents do not arise spontaneously they must recently have come from somewhere, usually from animal infections, as occurred with HIV infection, Ebola, influenza and Severe Acute Respiratory Syndrome (SARS) (Morens and Fauci 2013). Zoonoses on the other hand are diseases or infections which are naturally transmissible from animals to humans. According to the National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) 2013, approximately 75% of recently emerging infectious diseases affecting humans are diseases of animal origin and approximately 60% of all human pathogens are zoonotic.
Transboundary animal disease outbreaks can be attributed to increasing globalization due to better sea, land and air transport of people, animals and goods; normadism, transhumance and movement of refugees and their animals away from wars and civil disturbances. Outbreaks are also attributed to changes in livestock production systems due to intensification and commercialization of livestock farming leading to the spread of livestock farming into new ecosystems such as tropical rain forests placing human communities and their farm animals into close contact with a completely new range of infectious diseases which may have previously only circulated in wild life reservoirs and may be completely unknown. Global warming and the decline in government veterinary services and other infrastructures are also factors that contribute to the increased outbreaks of transboundary animal diseases (Chris et al 1999).
According to World Health Organization (WHO) 2014, the Ebola virus outbreak was first recorded in Zaire (The Democratic Republic of Congo of Central Africa) in the year 1976. Outbreaks of Ebola virus disease with the exception of the Reston Ebola virus have mainly been restricted to Africa and its recent outbreak is classified as the largest ever in nearly four decades of history of the disease in terms of numbers of cases and deaths. The virus is highly virulent and contagious often consuming the population but government and individuals’ quick response to quarantine areas may help to contain an outbreak (WHO, 2014).
TABLE 1: SHOWING SOME EMERGING/REEMERGING ZOONOTIC TRANSBOUNDARY ANIMAL DISEASES (NCEZID, 2014)
DISEASES INFORMATION Middle East Respiratory Syndrome (MERS-Cov) It is caused by Novel Corona Viruses. First identified in April 2012 and has since been seen in 9 countries- France, Germany, Italy, Jordan, Qatar, Saudi Arabia, Tunisia, United Arab Emirates and United Kingdom with all cases having some connection with the Middle East either directly or indirectly. Basic information such as the natural host, route of entry and mechanism of transmission remains unknown and about half of the human cases resulted in deaths. Nipah virus encephalitis Emerged from bats and caused epizootic in herds of intensively bred pigs which then served as animal reservoir from which the virus was transferred to humans. Severe Acute Respiratory Syndrome (SARS) Caused by Corona viruses. Emerged from bats and spread into human population through person to person transmission then human movement. Influenza
H5NI Virus
H791 Virus
H6N1 Virus
Transmitted from wild birds to domestic poultry then humans.
First reported in poultry in China in 2013. Human infection occurs after exposure to infected poultry or contaminated environments. 137 cases with 45 deaths have been reported. No cases outside China have been reported.
Commonly isolated from wild and domestic avian species with no human cases previously reported until May 2013 when the virus was isolated from a symptomatic 20-year old woman.
Objectives
The objectives of this study are therefore:
To understand the nature etiology of the diseases and how it is manifested in both man and susceptible animals.
To review the various implications of the emerging/reemerging Ebola virus on livestock and human population.
To assess the possible ways by which the transboundary animal disease (Ebola) can be controlled.
Research Questions
The following research questions guide this study:
What is the nature etiology of the diseases and how it is manifested in both man and susceptible animals?
What are the various implications of the emerging/reemerging Ebola virus on livestock and human population?
What are the possible ways by which the transboundary animal disease (Ebola) can be controlled?
Scope of the Study
This study focuses on examining the transmission of ebola virus on animal and humans. The study seeks to understand the nature etiology of the diseases and how it is manifested in both man and susceptible animals. This study will also review the various implications of the emerging/reemerging Ebola virus on livestock and human population. Finally, this study will assess the possible ways by which the transboundary animal disease (Ebola) can be controlled. This study shall use secondary sources of data collection.
Definition of Terms
Transmission:
Transmission is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected.
Ebola Virus:
Ebola virus disease (EVD) is a deadly disease with occasional outbreaks that occur mostly on the African continent. EVD most commonly affects people and nonhuman primates (such as monkeys, gorillas, and chimpanzees).
Animal:
A living organism that feeds on organic matter, typically having specialized sense organs and nervous system and able to respond rapidly to stimuli.
Chapter Five
Conclusion and Recommendations
Conclusion
Ebola can be fatal. Those in close contact with an infected person’s body fluids are at high risk of contracting the virus themselves.
EBOV is a highly pathogenic virus that has caused an increasing number of outbreaks in central Africa with largest outbreak ever documented in 2014. Because of its high fatality rate and potential use as a bioweapon, it is very important to understand its mechanisms of pathogenesis and, ultimately, to develop vaccines and therapeutics. The current model for EBOV pathogenesis is that, after entering the host, EBOV targets macrophages and DCs, thereby inducing an inflammatory state with high levels of proinflammatory cytokines. At the same time, the virus evades the immune response by several mechanisms including IFN antagonism, depletion of NK cells and lymphocytes and impairment of DC function. The produced cytokines and the direct infection of macrophages trigger the expression of TF, thus provoking a pro-coagulant state, which in turn further enhances inflammation. The procoagulant state develops into DIC and the released cytokines impair endothelial barrier function, which together might lead to severe shock and death. Although there are currently no approved vaccines or treatments for EHF, rNAPc2 and at least two recombinant virus vaccine approaches have shown promise in the NHP model. Further research into the molecular details of the viral life cycle and virus–host interactions will help develop further approaches to counter EHF. Of special interest will be to understand the pathogenic mechanisms that underlie vascular instability, coagulopathy and immunosupression (e.g. depletion of lymphocytes and impairment of DCs).
Washing hands properly, putting on and removing personal protective equipment safely, and other measures are essential. Because Ebola has the potential to spread across borders, it is important for all countries to be prepared in relevant infection prevention and control measures.
In Africa, fruit bats are considered natural hosts and reservoirs of the Ebola virus, while the involvement of other species in the EBOV transmission cycle is still unclear, especially for domesticated animals.
Ebola outbreaks have been observed in chimpanzees, gorillas, macaque monkeys and in some pigs in the Philippines and China. These latter animals, like human beings, have been considered as “accidental hosts” and not reservoirs of the Ebola virus.
Dogs and pigs are so far the only domestic animals identified as species that can be infected with EBOV. While infections in dogs appear to be asymptomatic, pigs experimentally infected with EBOV can develop clinical disease, depending on the virus species and possibly the age of the infected animals.
In the experimental settings, pigs can transmit Zaire-Ebola virus to naive pigs and macaques monkeys; however, their role during Ebola outbreaks in Africa needs to be clarified.
The risk of infection among humans from animals may be reduced by avoiding contact with fruit bats or monkeys etc. avoiding consumption of their raw meat and ensuring that all animal products are thoroughly cooked before consumption. Animal handlers are advised to wear gloves and other protective clothing.
Recommendations
The following precautions can help prevent infection and spread of Ebola and Marburg
Avoid areas of known outbreaks. Before traveling to Africa, find out about current epidemics by checking the Centers for Disease Control and Prevention website. •
Wash your hands frequently. As with other infectious diseases, one of the most important preventive measures is frequent handwashing. Use soap and water, or use alcoholbased hand rubs containing at least 60 percent alcohol when soap and water aren’t available.•
Avoid bush meat. In developing countries, avoid buying or eating the wild animals, including nonhuman primates, sold in local markets•
Avoid contact with infected people. In particular, caregivers should avoid contact with an infected person’s body fluids and tissues, including blood, semen, vaginal secretions and saliva. People with Ebola or Marburg are most contagious in the later stages of the disease. •
Follow infection-control procedures. If you’re a health care worker, wear protective clothing, such as gloves, masks, gowns and eye shields. Keep infected people isolated from others. Dispose of needles and sterilize other instruments. •
Don’t handle remains. The bodies of people who have died of Ebola or Marburg disease are still contagious. Specially organized and trained teams should bury the remains, using appropriate safety equipment. •
Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or monkeys/apes and the consumption of their raw meat. Animals should be handled with •
Gloves and other appropriate protective clothing. Animal products (blood and meat) should be thoroughly cooked before consumption.
Reducing the risk of human-to-human transmission from direct or close contact with people with Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective equipment should be worn when taking care of ill patients at home. Regular hand washing is required after visiting patients in hospital, as well as after taking care of patients at home.
Reducing the risk of possible sexual transmission, based on further analysis of ongoing research and consideration by the WHO Advisory Group on the Ebola Virus Disease Response, WHO recommends that male survivors of Ebola virus disease practice safe sex and hygiene for 12 months from onset of symptoms or until their semen tests negative twice for Ebola virus. Contact with body fluids should be avoided and washing with soap and water is recommended. WHO does not recommend isolation of male or female convalescent patients whose blood has been tested negative for Ebola virus. •
Outbreak containment measures, including prompt and safe burial of the dead, identifying people who may have been in contact with someone infected with Ebola and monitoring their health for 21 days, the importance of separating the healthy from the sick to prevent further spread, and the importance of good hygiene and maintaining a clean environment.
