THE EBOLA Reston virus, which now threatens the local hog industry, is harmless to humans, for now.
The virus has struck hog farms and slaughter houses in the provinces of Bulacan, Pangasinan, and Nueva Ecija, and five people have tested positive for Ebola Reston antibodies.
The question is whether the virus has jumped to humans from pigs, and whether it was indeed transferred to pigs from monkeys.
Ebola virus is the viral agent of Ebola hemorrhagic fever, a disease characterized by internal and external bleeding, vomiting, and rashes. It can lead to death following an incubation period of 21 days upon exposure.
According to Dr. Joey Matro, a mycology and virology professor of the Faculty of Pharmacy, the Ebola virus can be transmitted through contact with body fluids. The mortality rate is 60 to 90 percent among victims.
“Once a person contracts the virus, the onset of illness is sudden, while the hemorrhagic phenomena will develop at its height,” he said.
Double dead
Owners of pig farms affected by the virus voluntarily sent samples to the Plum Island Animal Disease Center in New York. Some pigs died of porcine reproductive and respiratory syndrome, and were found to be positive for Ebola Reston. The Ebola virus was found in six out of 28 samples sent to the disease center in October.
Last Jan. 6, the health and agriculture departments announced the arrival of animal and human health experts from the World Health Organization, Food and Agriculture Organization, and the World Organization for Animal Health. Together with technical teams from the Department of Agriculture and the Department of Health, they conducted a 10-day mission to assess the extent of the spread of the Ebola Reston virus among pigs.
Dr. Lyndon Lee Suy, program manager for emerging infectious diseases at the Health department, said authorities wanted to find out if Ebola Reston alone can cause disease among swines.
“Upon inspection of the dead pigs, it appears that there were other diseases that afflicted them. Maybe the clinical manifestations are caused by those other diseases and since the swine has a depressed immune system, Ebola Reston is given a chance to penetrate the pig’s body,” he told the Varsitarian.
The mission was also tasked to determine the mode of transmission of the virus to pigs, or whether it came from monkeys or even humans, he said.
“We need to establish where it came from to know how to control the disease,” he said.
They took blood samples from pigs in affected farms and from workers who had direct contact with the pigs. Results of the study were still unavailable as of press time.
Last Jan. 16, Health Secretary Francisco Duque III said results of separate tests performed in the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia will come in a few weeks.
Pigs trump monkeys
The first Ebola Reston outbreak occured in 1989 at Reston, Virginia, along with simian immunodeficiency virus — a virus that affects primates and believed to be a precursor of the human immunodeficiency virus — which killed quarantined cynomolgus monkeys, also known as Philippine long-tailed monkeys.
In her honor’s thesis published online, Tara Waterman of Stanford University found that there were more deaths than usual among monkeys after the shipment to the US of 100 more of the same species, which were later discovered to have been infected with the virus from a primate export facility in Laguna. In 1990 and 1996, deaths of cynomolgus monkeys in Texas caused by the same virus from monkeys of the same Philippine exporter were also recorded.
CDC findings show that monkeys which have contracted the pathogen suffered from a three-day illness characterized by anorexia, leading to loss of appetite or avoidance of food, and lethargy.
There are still no concrete theories on how the virus was transmitted to swines although other animals such as bats can carry the virus, Lee Suy said. Health authorities want to know whether the virus can be transferred to humans from infected pigs, as was demonstrated by the findings released in Jan. 23 on one Ebola-positive farm worker.
“The probability will always be there. But will the virus manifest itself and cause an illness? If you observe the characteristics of the virus, it has a low level of pathogenicity which means that if you contracted the virus, it may not cause a disease,” he said.
Matro noted that in terms of the spread of other diseases such as influenza, pigs have already shown their capability to serve as “mixing vessels” where viruses can mutate to forms that can jump to humans.
“In terms of influenza, two strains may undergo reactions within the pig’s body which may result in another strain of virus that may affect humans,” he said.
While no human has died of Ebola Reston so far, Lee Suy advised consumers to cook food thoroughly and purchase meat products approved by the national meat inspection service.
