Understanding The Factors Contributing To The Transmission Of Ebola Virus Disease

Role of causative agents and reservoirs

Question:

Discuss about the Ebola Virus Disease.

Ebola virus disease (EVD) or Ebola hemorrhagic fever is a fatal disease transmitted to humans from wild animals and transmitted to human population by human-to-human transmission. The virus was first observed in 1976 in South Sudan and Congo and the re-emergence of the Ebola outbreak in West Africa in 2014-2016 was among the most complex and largest outbreak since 1976. The first symptom of the Ebola virus disease is sudden onset of muscle pain, fever and headache followed by vomiting, kidney and liver impairment, internal and external bleeding (Ebola virus disease, 2017). One of the biggest threats is that sick patients mainly bleed and the blood and body fluids of such individual are very infectious increasing the risk of transmission in other people. As the 2014 Ebola outbreak in Western Africa was regarded as the most severe in history, the World Health Organization declared it as a public health emergency. Considering the high risk of intercontinental transmission of Ebola, it can be said that global threat of transmission is huge (Kalra et al. 2014). Several countries have recognized Ebola as public health threat and taken different measures and coordinated action to eliminate the risk of outbreak. To enhance the efficacy in the global and country wise efforts to prevent the Ebola outbreak, the main purpose of this essay is to present a critical literature review on the role of agent, host and environmental factors causing EVD and evaluate the policy response to prevent the epidemic in Australia.

As Ebola is communicable disease whose threat has been realized mainly in the period between 2014-2016, all research literature between 2014-2017 is reviewed to understand how difference factors shape patterns of communicable disease like EVD in affected countries and Australia. The first element that needs to be reviewed to understand the threat of Ebola virus disease is the role of agents in its diagnosis and transmission. Ebola virus is the main causative agent of Ebola Hemorrhagic fever and the virus belongs to the family of filoviridae. The virus is found to be fatal both for human and non-human primates resulting in high mortality rates. The virus got its name from a river in Democratic Republic of Congo in Africa where the virus was first discovered in 1976 (Profiles of Ebola, 2017). Research has mainly showed that natural reservoir of Ebola virus is not known, but it is predicted to be a native to Africa. New genomic technologies provided idea regarding the pathogen’s origin, transmission dynamics and evolution. People were found to be infected by the virus by handling infected primates. Human to human transmission occurred by direct contact with blood, saliva and the excretions of infected person. The chance of nosocomial infection is also a possibility. Variation in patterns in intrahost and interhost has given insight about transmission and epidemiology of the Ebola disease (Gire et al., 2014). 

Environmental factors in EVD transmission

Many studies have also been done to identify the main reservoir of Ebola virus. Although specific reservoir has not been clarified however evidence supports fruit bats as one of the reservoir of the virus (Oliva et al., 2013; Dixon & Schafer, (2014). Dixon & Schafer, (2014) gave detail regarding the modes of transmission of virus and the incubation period of 2-21 days. The first mode of transmission is the contact with infected wildlife and then spreading of the virus through person to person contact. The Ebola virus disease is also transmitted at different stages of the disease event at post mortem by coming in contact with the dead body after funeral preparation. The diagnosis of the disease is mainly done by the ELISA testing and PCR and detection of Ebola virus antibodies confirms the disease. In the context of the reservoir of Ebola virus in Australia, it can be said that till date there is evidence for the presence of Ebolavirus in Australians bats or native animal. No human Ebola virus disease cases have been found in Australia, however taking control measures to prevent transmission is necessary considering intercontinental risk of transmission (Department of Health, 2017).

Apart from the reservoirs or host of Ebola virus, there are certain environmental factors too that influence the spread of communicable diseases like Ebola. The role of environment factors in EVD transmission and outbreak is evident from studies done to evaluate the factors leading to emergence of Ebola in Africa. For instance, Alexander et al., (2015) explained human mediated environmental changes played a major role in the emergence of Ebola virus in outbreak zone. For example, the Guinean forest in Africa is a major biodiversity hotspot, however human encroachment in these areas resulted in directed exposure to infected bats. This eventually created direct transmission pathways to disease outbreak. In terms of major EVD outbreak specifically in West Africa, it can also be said that social conditions like population growth, poverty and poor health infrastructure increase the size of the EVD epidemic. The study regarding EVD outbreaks in Guinea showed that increase in population density had a critical impact on human-to-human transmission and environmental degradation (Baize et al., 2014). Hence, it can be said that certain social factors increased the length of exposure to virus and led to the development of many transmission chains which eventually increased the number of EVD cases.

In the year 2014, the confirmed and probable case of EVD was found in five countries such as Sierra Leone, Guinea, Liberia, Nigeria and Senegal and it resulted in about 4922 deaths. Considering the severity of the epidemic, it became evident that taking drastic control measures became essential both for Africa and other countries (Bickler, Lizardo & De Maio, 2015). The probability of risk and infection is high because only one or two viral particles is needed to infect a person. Bickler, Lizardo & De Maio, 2015) also pointed out that different environmental factors influences the physiology and susceptibility of any disease. This could be said because gene expression studies revealed that transcriptomes of peripheral blood leukocytes is differently expressed due to the effect of environmental geography. In recent years, the Niemann-Pick C1 (NPC1) protein, the receptor of Ebola virus was identified and study of NPC1 expression in urban and rural populations in Africa revealed that NPC1 is upregulated in rural population compared to urban population. This indicates that environmental condition has impact on the expression of these genes. These findings may play a key role in understanding the mechanism of infection and taking appropriate control measures.

Impact of social and psychological factors

Major countries worldwide are currently striving to prevent the emergence of Ebola. Considering the above explanations regarding the role of environment in contributing the epidemic, it can be said that better understanding of the environmental links to the disease can help countries to effectively fight against Ebola. For example, countries can get idea about the environmental links to transmission by the information regarding the Ebola virus in environment. The glycoprotein is the main mediating force responsible for attachment and infecting the host cell. Ebola virus is an enveloped virus mainly found in animal wastes and excretions and presence of such waste in the environment enables it to persist even outside host’s body (Cedrine et al., 2017). Hence, the main implication from the above finding is that sanitation should be a major emphasis for countries to manage the environment and prevent the transmission of EVD. The long term public health infrastructure needs to be developed so that safe drinking water, sanitation and hygiene conditions are available for all citizens (WASH and Ebola, 2017). 

Apart from the role of causative agent, reservoirs and environmental factors in Ebola virus transmission, another essential thing that must be a focus of public health attention is the behavior of common citizens. Ebola was a national epidemic crisis for Africa and the interaction of both socio-cultural and environmental factors contributed to certain negative behavioral response by public. A research done to investigate the relationship between spread of EVD, public attentions and community’s response to the epidemic revealed that psychological and socio-cultural factors of individual has adverse impact on the spread of disease. In epidemic zone, adverse effect of socio-cultural factors was realized by the rise in the number of cases of EVD. This finding also points out to a new area of focus for public health department which is to redirect negative psychological and socio-cultural behavior of public to reduce the Ebola outbreak (Sharareh et al., 2016). Many researchers proposed several unique strategies to reduce the transmission rate. Gimm & Nichols, (2015) suggested to identify people who are infected or at risk of infection and quarantine the symptomatic individuals. However, the limitation in this strategy is that no information related to change in public behavior has been proposed. Isolation of infected or at risk person can also be a solution to curb the transmission rates, however this may lead counterproductive reactions from the public due to the violation of human right (Calain & Poncin, 2015).

Evaluation of policy responses

Another research gave useful evidence regarding the role of fear related behavior in shaping outbreak and increasing the risk of future harm. Fear related behavior of people was found to have an impact on accelerating the rate of Ebola, restricting use of life saving treatment, increasing the risk of psychological distress and making available medical services ineffective. The study of fear related behavior in epidemic zone mainly revealed that due to fear, many families took EVD treatment and care secretly in home instead of going to Ebola treatment centers. This was the driver for the spread of the disease and decreased the chances of survival in such groups. Death in home setting was also the reason for high rate of Ebola virus transmission as no proper protection was taken for while handling beddings, utensils or corpses of affected individuals. Other fear related behavior witnessed in the study included migrating to new settings, avoiding life saving treatment and less availability of health care workers for hazardous duty (Shultz et al., 2016). Hence, many useful lessons can be taken from fear related response of public. To improve the preventive efforts for EVD in the future, countries like Australia can focus on modifying the fear related behaviors by recruiting disaster psychiatrist in the health promotion process. They may help mitigate fear related behavior and come in contact with people at the right point of time to reduce the casualty rate.

Based on the limitations and possible ethical implications in taking strategies to improve negative behavior of public in response to the Ebola crisis, it can be said that national government and public health staffs must focus on system dynamics approach to influence people’s perception and response to the outbreak. For example, Australia is also focused on addressing the risk of EVD transmission in their county by means of overseas travel. They can adapt future models for disease prevention by focusing on awareness of public to outbreak preparedness and collaborative taking part to follow disease prevention protocols and minimize the casualty associated with Ebola (Sharareh et al., 2016).

The above discussion mainly developed the understanding regarding the different factors that plays a role in transmission of EVD and increasing the risk of diagnosis in certain groups. The next critical step is to evaluate the policy responses implemented so far to curb the epidemic and find out weakness and strengths of those policies. The most significant policy related to outbreak prevention and control was the vaccination policy. Prophylactic vaccination and reaction vaccination strategies were  implemented to prevent early epidemic  transmissions. A research investigated the role of both these strategies to decide future policies related to vaccination. The review of data in affected countries showed prophylactic vaccination to be more effective in preventing early transmission compared to reactive vaccination. As fear related health behavior studies showed that health care workers avoid working in Ebola cases due to hazardous nature of task, their participation can be increases by considering long lasting immunity of health care workers by means of prophylactic vaccination campaigns (Coltart, Johnson & Whitty, 2015). Hence, effective implementation of prophylactic strategy can provide additional benefits to countries to mitigate the chains of early transmission.

In response to the Ebola outbreak, the first priority of the Australian government was to keep Australians safe and secure by increase in screening for Ebola (Department of Health | Ebola, 2017). Screening measures were mainly implemented at airports and seaports to identify passengers form EVD affected countries. They are still monitoring all people entering Australia from West Africa and monitoring all people who return from Ebola affected countries. The main advantage of the screening policy or strategies adapted by Australia was that they made sure to establish a system of monitoring till the 21 day incubation period. They also provided regular notifications to the World Health Organization’s Health Regulation Focal point to ensure that people at high risk could be identifies and appropriate protection measures could be taken on time (Department of Health | Downscaling of Ebola border screening measures, 2017). Hence, it can be said that Australian government mainly focuses on airport screening measures due to the high risk of intercontinental transmission of Ebola virus. The main advantage of such airport or traveler screening is that it is the best method that directly targets the risk of transmission in other countries just at the entry points. It curtails geographic spread of infections (Gostic, Kucharski & Lloyd-Smith, 2015). In addition, the effectiveness of such screening is also dependent on epidemiology and natural history of infection.

Another important policy response taken by Australia to curb the Ebola epidemic was to immediately implement the visa suspension policy. The study regarding countries response to WHO’s travel recommendation during the 2013-2016 Ebola outbreak gave idea regarding the implementation visa suspension policy by Australia. The Australian Department of Immigration announce temporary suspension of all visa application for citizens belonging to Ebola affected countries and cancellations for all those Australians who were is Ebola affected countries within the 21^st day (Rhymer & Speare, 2017). Although this was an appropriate response taken by the Australian government to fight against the epidemic, however this move resulted in resentment from countries like Sierra Leone. They also blamed that the visa suspension policy was counterproductive and discriminatory (BBC News, 2017). Australian government has to finally justify their action of suspension by explaining the immediate need for such move. However, despite resentment,  it can be rightly said that by taking this measure, Australia was not at all withdrawing support to affected countries. The advantage of this policy implemented by the Australian government was that by implementing these measures, they were reducing all the possible risk of transmission as well as supporting assistance to affected countries.

In response to the risk of transmission by travelling to affected countries, the Australian Department of Foreign Affairs and Travel took the step of advising Australians to reconsider their travel plans in Africa. A list of guideline were also prepared for Australian citizen in case they were travelling to Africa and this mainly included consideration about medical evaluation and the step needed if any person returns from affected countries and feel unwell. The Australian government has also developed a national protocol to ensure that public health staffs take immediate steps to respond to suspected or confirmed case of EVD. However, great limitations were found in the risk assessment process implemented in Australia following special guidelines for prevention. Firstly, delays were seen in the transport of specimens and patients to the hospital. The routine laboratory test was associated with many issues due to concern about laboratory safety. Due to these, it can be said intensive monitoring is necessary with special training of health care workers as well as proper education for health care staffs (Gilbert, 2016). Hence, the review of policy responses linked to Ebola makes it clear that certain measures like airport screening was effectives but lack of preparedness were seen in educating public and health care workers and improving their behavior to curb the epidemic. There is a need to take lessons from various environmental factors and other causes leading to epidemic in affected countries and adapt upgraded strategies for community health and well being.

The essay mainly summarized the global epidemic crisis caused due to the reemergence of Ebola. The discussion regarding the role of agents, reservoirs, transmission modes and environmental factors associated with the disease mainly gives the implication that the Ebola virus is highly infectious and extensive control measures is needed to curb the epidemic. The review of potential policy response to prevent Ebola outbreak in Australia gave idea about quarantine measures, visa suspension, airport screening and guideline for international travelers implemented in Australia. However, as certain measures were associated with public resentment, there is a need to analyze the fear related behavior of people and find the best strategies that save Australia from human rights issue as well as promote acceptance of the strategy by the common public and other countries.

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