Nipah Virus and the Potential for Bioterrorism

Introduction

Bioterrorism is considered to be one of the most talked about issues with regard to national security since the inception of the new millennium. On September 11, 2001 (9/11) terrorism struck the United States with the crashing and attempted crashing of airplanes into significant economic and political buildings. This “act of terror” was a significant beginning to fears of “what was next” from terrorist groups. Even though this was not the first, and definitely not the last, terrorist threat or attempt it was definitely the most profound and unquestionably caused fear, panic and social disruption much less economic issues globally.

Within days of the 9/11 attacks the awareness of American vulnerability became more evident with the media publicity of the Anthrax scares. This brought about international concerns with bioterrorism as envelopes that were filled with anthrax spores were sent to political and media sources throughout the United States and twenty-two people were infected and five deaths occurred (Ryan & Glarum, 2008).

Nipah is just one of many viruses that are available to terrorist groups for development as a bioweapon. In 1999 this virus was first found and noted to be very easily disseminated to humans through inhalation and ingestion. Even though there are many potential pathogens available, the Nipah virus has proven itself to be one of the most dangerous and advantageous .

As the Nipah virus progressed there was fear noted by workers, families and healthcare providers in southern Asia. With a mortality rate of 40% to 100% (Lam, 2002; World Health Organization [WHO], 2009) in infected areas, and an economic impact that cost several millions to Malaysia’s economy, this virus has potential for significant bioterrorism.

Natural History

The Nipah Virus (NiV), family paramyxoviridae, was first recognized in Malaysia, South Asia in late 1998 into Spring 1999. This disease was recognized when an outbreak of sickness and death occurred among pig farmers, it infected 265 people, with 105 deaths, a mortality rate of approximately 40% (Lam, 2002).

This virus was new to the scientific community and first thought to be Japanese Encephalitis (JE) which had occurred in approximately the same location years earlier. JE was also noted to infect people that were around domesticated pigs, just like the currently identified Nipah Virus (Center for Disease Control [CDC], 2001). The Nipah virus was found to also have similar symptoms as those of the Hendra Virus which caused respiratory disease and encephalitis in Australia in 1994 (Fraser, 2009). The Nipah virus is considered by the CDC as a “newly emerging pathogen” that could be engineered for mass dissemination (Ryan & Glarum, 2008; Center for Disease Control and Prevention [CDC], n.d.).

Since the onset of the Nipah virus in 1999, according to the World Health Organization (WHO), there have been twelve significant outbreaks since the initial, with 202 persons infected and a loss of life of 146 individuals, mortality of over 72%. Two of these outbreaks, one in India in 2007 and one in Bangladesh in 2008 had mortality rates of 100%, showing the devastating effects of this virus (WHO, 2009).

The initial investigation of the Nipah virus found that abattoir workers who dealt with pigs daily and those that were exposed through farming and transporting pigs were getting ill. As the investigation continued it found that the pigs were infecting the workers (zoonotic disease). After discovery, subsequently over 1.1 million pigs were disposed of to quell the transmission of the virus. This destruction of pigs was significantly devastating to the economy of Malaysia noting an estimated loss of $217 million dollars (Ryan & Glarum, 2008, p. 104).

Virus Transference

The Nipah virus host was found to be pteropid bats (flying foxes), located in Australia and the southern areas of Asia. During expansion of farms toward the rainforests and the destruction of the rainforest for manufacturing and industry, many animals including bats had to relocate to survive. Many pig farmers in Malaysia also had large fruit orchards situated next to the pig enclosures, as growth of pig farming continued and the loss of habitat for bats persisted to change bats started to forage the nearby orchards for food. As this progression continued there was an increased chance of disease contamination to domestic animals from wildlife, and as such a significant increase in contact between pigs and bats. Therefore, greater opportunity for transmission of the Nipah virus (“Dr. Jonathan Epstein Returns“, 2005).

As the Nipah virus was investigated it was believed to have been transmitted to pigs from bats through the saliva, urine and feces of the bats which feed and nest in local orchards (“Dr. Jonathan Epstein Returns“, 2005), near pig pens. This potential transmission probably occurred when bat secretions fell into the pig pens and were ingested by these domesticated animals.

The initial human virus outbreak in Malaysia and Singapore was believed to have been from direct contact with sick pigs or their meat products, and possibly could have come from the consumption of contaminated fruit or juices from the orchards. As the virus progressed and research was done there was an established link noting person-to-person contamination through close contact (World Health Organization [WHO], 2009)

Physiology of Exposure

The Nipah virus seems to have many different clinical manifestations in individual animals and humans. There is a broad range of clinic signs that can point to virus infection that cause researchers and healthcare providers to not recognize patterns of initial infection, therefore not recognizing potential disease outbreaks. According to the WHO (2009), “the incubation period (interval from infection to onset of symptoms) varies from four to 45 days”. This significant range makes it incredibly hard to follow the virus between initial exposure and medical treatment. Recognizing that the person is showing signs of a virus, and narrowing down the specific virus, then treating it appropriately for an individual is a challenge but feasible. But with such a wide incubation period there is a possibility that viable information could be lost or not noticed.

The physiological symptoms of this “virus” in humans is characterized by non-specific signs and symptoms to include severe headache, fever, vomiting, myalgia (muscular pain) disorientation, respiratory diseases, neurological deficits and encephalitis and in many cases may cause coma or death (Center for Infectious Disease Research & Policy [CIDRAP], 2009).

In pigs there is characterization of signs and symptoms depending on the age of the animal. The basic signs noted are fever, shortness of breath, muscle twitching, trembling, rear leg weakness, severe coughing, open-mouth breathing, abnormal posturing and convulsions (CIDRAP, 2009).

After initial exposure and treatment follow-up research was done and in this study it was noted that there were relapses in clinic symptoms to include encephalitis up to twenty-two months later, without re-exposure. The research and that an “estimated 160 patients who recovered from acute encephalitis and 89 patients who experienced asymptomatic infection received follow-up care for ‘late-onset’ encephalitis (neurological manifestations occurring for the first time at ten or more weeks after initial infection) or ‘relapsed encephalitis’ (neurological manifestations after recovery from acute encephalitis) (Halpin & Mungall, 2007, p. 290).

Host Sources

The Nipah Virus’ source comes from Pteropus fruit bats (AKA: Flying Foxes), which are found in Southern Asia and Australia. In 1997 fruit bats were noted to begin foraging on flowers and nectar in trees located near orchards contiguous to infected areas (Cobey, 2005). Fruit bats were found to be the natural source of this virus and caused the transfer of the virus to pigs and human beings. As domesticated pigs were sold for breeding and transferred to other farms the virus was quickly disseminated further throughout southern Asia (Cobey, 2005).

Possible Use in Biowarfare

Biowarfare, and in this day and age bioterrorism, is a threat that began before the birth of Christ. According to Dr. Michael D. Phillips, M.D. “one of the first recorded incidents [of bioterrorism]was in Mesopotamia. The Assyrians employed rye ergot, an element of the fungus Claviceps purpurea, which contains mycotoxins. Rye ergot was used by Assyria to poison the wells of their enemies, with limited success” (Phillips, 2005, p. 32). Use of pathogens to induce sickness, death or terror has continued until present time.

The Centers for Disease Control and Prevention (CDC) has listed the Nipah virus as a critical biological agent, Category C. Category C agents are emerging pathogens that could be engineered for mass dissemination in the future because of:

* Availability

* Ease of production and dissemination

* Potential for high morbidity and mortality rates and major health impact (Center for Disease Control and Prevention [CDC], n.d., ¶ 3; (Ryan & Glarum, 2008, p. 105))

With this categorization the virus is a living pathogen that can be developed as a bioweapon with the right knowledge, and equipment. For the virus to be weaponized it needs to be purified, stabilized and properly sized. Since this is a living virus the bioterrorist agent can be replicated once disseminated (Ryan & Glarum, 2008). At this time, there is no information about how this virus could be manufactured to become a bioterrorist agent, but with the right knowledge the potential is there.

Production Methods

Since the Nipah virus has proven to be disseminated through secretions from bats and pigs, and shown to cause severe infection and death it can potentially be used as a bioterrorist agent with little changes in its basic state. If the excretions from infected bats in palm juice can cause infection and death then there is ease in distribution with a significant amount of virus.

Even with these basic distribution methods there is information about the Nipah virus and its compounds being published. As knowledge continues be found about the virus and information availability of the compounds there is potential for virus manipulation for maximum threat to animals and humans to induce fear and panic. Information such as this is noted in an article by Medical News Today, (2005). This article states that UCLA scientists have revealed how the Nipah virus infiltrates human cells. The article further states the virus “exploits a protein that is essential to embryonic development to enter cells and attack”. The virus must infect a cell by binding to a viral-specific receptor and once that is done penetrates the cell. The article actually gives the receptor name as Ephrin-B2, and is found to be the key to unlocking these dangerous cells. If this information is so easily accessible and is available it allows terrorists groups with the knowledge and expertise to manipulate the virus for dissemination and extreme virulence.

The Nipah virus is still a relatively new virus and steps are slowly being made in understanding this infant virus. As of this time there is very little knowledge about how effective this virus would be or what would be needed to make it infective. With bioterrorist there is always a concern with the storage and stability of the virus for development and weaponization. As developments are made and intelligence is gathered with regard to potential agents there will be a concern with any viral pathogen.

Transmissibility

Animal-to-human

Animal (pig) to human transmissibility was the first noted issue with regard to the detection of the Nipah virus in 1999. As stated earlier the virus spread rapidly and was found to have started with pig farmers and abattoir workers that worked closely and handled these animals. As the virus progressed and workers died it was found that pigs in these farms had been coughing loudly (bark type of cough), and nerve damage was becoming prevalent. In a short amount of time approximately five percent of these animals died and the illness was spreading significantly (Pearl, 2006).

Also transmissibility has been noted from non-specific animal contact put through the ingestion of date palm juice taken from the trees that bats nest and feed. As the fruit tree workers and farmers gather the palm juice through clay pots bats drink from the pots and transfer saliva to the nectar (Pearl, 2006).

Person-to-person

Many of the articles written on the Nipah virus states that there is no evidence that there is transmissibility of the virus from person-to-person. In contrast, according to a research investigation done during a Bangladeshi outbreak in 2004, there is definitive evidence that the Nipah virus can be transmitted from person-to-person (Gurley et al., July 2007).

According to the research, subsequent investigations in India and Bangladesh have suggested that Nipah virus may have been transmitted from person-to-person. During an outbreak in 2001in India, 75% of the patients, including fourteen healthcare workers, had a history of hospital exposure to patients infected with Nipah virus (Gurley et al., July 2007), with no other exposure risks noted. The exposure, and subsequent virus, occurred with persons who lived with or cared for the patients, and persons who were in close contact for a significant amount of time.

According to a research article published by the CDC, the Nipah virus can be transmitted from person-to-person. The article states, in a densely populated area “a lethal virus could rapidly spread before effective interventions are implemented. This spread would provide the seed for a substantial regional or global public health problem” (Gurley et al., 2007, p. 1036).

According to Gurley et al., 2007 there is significant evidence that person-to-person contact will cause infection. The person-to-person transmissibility factors include having (1) touched or received a cough or sneeze in the face, (2) any contact with someone who later died, was febrile, unconscious, or had respiratory difficulty, and (3) visited the home, and possibly, the village an infected person.

The most significant evidence of person-to-person infections was with a religious leader where twenty-two persons who had became infected after close contact. The religious leader was moved to his home and eight members of his household became infected. Two brothers who lived a significant distance away were infected after only a six hour visitation, son-in-law and daughter who lived only about one hour away and eleven other followers of the leader contracted the disease after contact (Gurley et al., 2007) with no noted other infection means.

Surface-to-person

To this date there is no evidence of any transfer of the virus to persons from surface contact, in fact “how long the virus remains infectious on environmental surfaces is not known.” In an article written by (Gurley et al., 2007) collection of 468 environmental specimens were gathered through swabbing of potential surfaces that included walls, bed frames, mattresses, floors and utensils in hospital rooms and residences of infected individuals. Also collected were swabs from trees, fruits, excrement and other surfaces around possible bat foraging sites. With all of this gathered specimens the only information obtained was that the infected individuals shed the virus into the environment, showing potential for transmission, but no evidence was found that surfaces caused any positive infection to another person.

Potential for contagion and considerations relative to Biodefense

The Nipah virus has the potential to be a very detrimental bioweapon of choice for domestic or international terrorists. With the virus being zoonotic (disease which can be transmitted to humans from animals, [“Zoonosis“, 2009]), which effects animals and humans, and the ease of transmission from the saliva and urine of fruit bats to these two groups the potential for a

Potential for contagion and considerations relative to biodefense

According to Kortepeter and Parker (Kortepeter & Parker, 1999), for a biological agent to be used for a greatest plausible occurrence, an agent must have specific properties:

Conclusion

The Nipah virus should be a concern for any government as a potential for a bioterrorist attack. As with the 9/11 and the anthrax attacks in 2001 there could be significant fear, panic, economic issues and social disruption if this virus was used. With a mortality rate of 40% to 100% (Lam, 2002; WHO, 2009), and an incubation period of up to 45 days (WHO, 2009), this could definitely be a pathogen of choice for terrorists. The ease of access to the virus itself from fruit bats, to pigs and to humans, not to mention the transmissibility ease through inhalation and ingestion, makes this the perfect biological weapon.

The disease this virus manifests, from flu type symptoms to severe encephalitis, will cause significant fear to the public and will stress healthcare facilities if a large outbreak occurs. This virus also has no known cure as of this date, even though there are developments in that direction.

The Nipah virus needs to continue to be monitored and treatment options along with vaccine development needs to be continuous until this threat is diminished.

References

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