No one ever imagined that the Ebola virus, once common among monkeys and other primates, will find its way among swines. How is this possible? At this point, experts are still mystified while trying to understand the implications and consequences of the virus both to human and animal health.
Ebola is the common term for a group of viruses belonging to genus Ebolavirus, family Filoviridae and for the disease that they cause, Ebola hemorrhagic fever.
The virus is named after the Ebola River Valley in the Democratic Republic of the Congo (formerly Zaire), which is near the site of the first recognized outbreak in 1976, in a mission hospital run by Flemish nuns.
The viruses are characterized by long filaments, and have a shape similar to that of the Marburg virus, also in the family Filoviridae, and possessing similar disease symptoms. Since its discovery, the Ebola virus has been responsible for a number of deaths.
Ebola is thought to be a zoonotic virus, as it is currently devastating the populations of Western Lowland gorillas in Central Africa. As of late 2005, three species of fruit bats have been identified as carrying the virus but are not showing the disease's symptoms, and they are now believed to be the natural host species, or reservoir, of the virus.
Although it has been nearly 30 years since the discovery of the virus and roughly 1500 infected patients, some scientists believed that no organism has shown the ability to successfully house the pathogen in its body. However, investigators have theorized that fruit bats in African caves are the natural carriers of the virus.
Five Strains of the Ebola Virus
- Ebola Zaire. The Zaire virus, formerly named Zaire Ebola Virus, has the highest case-fatality rate, up to 90% in some epidemics, with an average case fatality rate of approximately 83% over 27 years. There have been more outbreaks of Zaire Ebola virus than any other strain.
- Ebola Sudan. The Sudan Ebola virus is the second strain of Ebola first reported in 1976. The virus has an average case-fatality rate of 54%. The first case reported was a worker exposed to a potential natural reservoir at a cotton factory in Nzara, Sudan. The most recent outbreak of this strain was documented in May 2004 in Yambio County where 20 cases of Sudaneses were reported resulting in five deaths. Presently, as in all the other Ebola strains, the carrier and the natural reservoir of the virus is still unknown.
- Ebola Ivory Coast. The Ivory Coast, the third strain of the Ebola virus,was first discovered among chimpanzees of the Tai Forest in Côte d'lvoire, Africa a November 1994. Studies of tissues taken from two chimps found dead in a forest showed results similar to human cases during the 1976 Ebola outbreaks in Zaire and Sudan.
- Ebola Reston. The Ebola Reston strain, the only known filovirus ever to originate in Asia was first discovered in Hazleton Laboratories (now Covance) in 1989 when crab-eating macaques (Maraca fascicularis) imported from the Philippines became ill and eventually died after becoming infected with this particular strain.
Although the Ebola Reston virus (ERV) has been shown to infect humans (i.e. 26 documented human cases since 1989), it has not been shown to cause significant human illness or deaths and is a less deadly strain for monkeys with a lower case fatality rate than the other African strains.
There have been subsequent outbreaks of the Reston Ebola virus among Philippine monkeys in 1990, 1992, and 1996. During these instances, some animal handlers developed antibodies specific for the Ebola reston virus. Only one, however, exhibited very mild flu-like symptoms and eventually recovered.
When the recent discovery of ERV in the country broke news, it bewildered the international health community because this is the first time that the virus was found in pigs - a domestic animal used for food and known to be an effective mixing vessel for other human and animal diseases.
- Ebola Bundibugyo.The Bundibugyo Ebola virus, the newest species of Ebola, was only discovered in November 2007 after the Uganda Ministry of Health confirmed an outbreak of Ebola in the Bundibugyo District. After confirmation of samples tested by the United States National Reference Laboratories and the Centers for Disease Control, the World Health Organization confirmed the presence of this new strain.
Transmission of the Ebola viruses between humans, particularly the deadlier strains found in Africa, is believed to be due to the reuse of needles without sterilization in patients. The risk is also high among individuals who perform traditional burial preparation methods, which involves washing and cleansing of the gastrointestinal tract.
There have also been documented cases of Ebola being transmitted to hospital workers caring for sick patients because they did not observe universal precautions.
Four Lines of Defense
Secretary Duque currently endorses the four lines of defense to limit the animal and human health risks of the Ebola Reston Virus. He stressed that the local governments, the hog industry as well as the public must play a critical role in observing these four lines of defense.
- First, unusual occurrences of sick or dying pigs should be reported to local veterinary or agriculture authorities. The nearest Provincial/ City/ Municipal Veterinary Officers should be immediately notified of such occurrences. NMIS officers or Meat Inspectors should not allow the slaughtering of any sick or dead pigs.
- Second line of defense, bio-security measures to prevent and contain any future outbreaks must be implemented and enhanced in all pig farms nationwide.
- Third line of defense is to prevent the entry of double-dead meat into the market. BAI has already enhanced its pig movement and shipment control, and increased strategically located quarantine checkpoints to prevent transport of sick pigs.
- Last line of defense involves thorough cooking of pork and pork products. Pork cooked at high heat (70°C) destroys and kills disease-causing organisms. All meat should always be cooked properly until there is no pink part in the meat and juices are running clear. Good kitchen hygiene should always be used when handling raw meat.
- Donato Dennis B. Magat. Health Beat Magazine Issue no. 52. Department of Health of the Philippines. (Accessed on May 27, 2010).
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