Authorities confirm ongoing transmission of Ebola Reston Virus in Bulacan, northern Philippines

Bureau of Animal Industry director Dave Catbagan and Agriculture Secretary Arthur Yap explain the hows and whys of depopulation

From a joint press release of the health and agriculture departments, dated Feb 23 2009:
Of 160 pig blood samples that were positive for antibodies, 133 came from Bulacan and 27 from Pangasinan as reported by RITM. Those from Bulacan were traced to pigs at different age groups while those in Pangasinan were found in sows and just one piglet.
This means that there is on going viral transmission in Bulacan but past infection with recovery was the case in Pangasinan.
Of the 19 pigs with tissue samples positive for ERV (Ebola Reston Virus) by real time RT-PCR, none came from Pangasinan since all were traced to Bulacan. This now confirms the earlier tests done by RITM that Bulacan has ongoing viral transmission.
“From the time of the collection of the samples up to the present, none of the pigs in both farms showed signs of any illness. Quarantine can now be lifted in the Pangasinan farm. However, as a precautionary measure, depopulation will be carried out in the Bulacan farm,” DA Secretary Arthur Yap said.
Experts explained that depopulation is done to prevent further spread of the Ebola Reston in pigs within and outside the farm. The Joint Mission recommended this management imperative considering that there was possible pig-to-human transmission and ERV comes from the Ebola family of viruses known to be highly pathogenic to humans. So far, the Reston virus remains to be the only strain not to cause significant illness in humans.
The RITM and US CDC tested about 147 human samples for Ebola Reston Antigens and Antibodies (either IgG or IgM). These came from the affected farms (Bulacan and Pangasinan) and from slaughterhouses in Pangasinan and Cabanatuan. Of these, six human blood samples were found to be positive for IgG antibodies.
“The additional positive human sample (five were previously reported) was traced to a slaughterhouse worker in Cabanatuan. This worker is male and was not sick during visits by the investigation team. He does not recall any direct contact with sick pigs but remembers having flu-like illness himself in the past 12 months. There is no evidence however that the flu-like symptoms can be attributed to ERV infection,” DOH Secretary Francisco Duque III said.
“To date, all close contacts of humans with positive antibodies who were tested have remained antibody-free signifying absence of illness in affected humans that can lead to possible human-to-human transmission. Ebola Reston poses a low risk to human health at this time,” Duque said.
“Pork is still safe to eat when properly handled and cooked adequately (no pink parts and juices run clear). Consumers are advised to source meat that has the National Meat Inspection Service (NMIS) seal,” Yap said.
The DA will expand surveillance to other farms in other areas as well. The DOH will carry out surveillance in those farms or areas where Ebola Reston will be detected. Both the DA and the DOH together with international and national agencies and partners will carry out further scientific studies to determine the source of Ebola Reston in pigs, characterize pig-to-pig and pig-to-human transmission and also infection or possible illness in pigs and humans.”

Meanwhile, the DOH and the DA are asking the public, livestock breeders and authorities to: report unusual occurrence of herds with sick or dying pigs; cautiously handle and dispose of sick and dying pigs; prohibit and confiscate double dead meat; cook pork thoroughly, with adequate heat.

This particular press release is more technical than the earlier ones. Basically, what it means is that: they found evidence of infection (through the presence of antibodies) in pigs that did not appear to be sick; this infection appears to be ongoing in Bulacan but not in Pangasinan; because of this, the herd in Pandi, Bulacan will have to be killed (some 6,000 pigs in all).

Also, right now authorities do not know how the virus is transmitted from one pig to another, or from pigs to humans. This is the first time that the virus has been found in pigs. The concern stems from the fact that while the Reston strain here in the Philippines do not appear to be that harmful to humans, they still belong to that Ebola family of viruses “known to be highly pathogenic to humans.”

BUT: the humans who have been infected so far are all well, and have not reported any signs of illness, except one. It is not sure if the flu-like illness reported by one man in the past 12 months was caused by the Ebola Reston Virus. That man, also, does not remember having handled pigs that appeared to be sick (dovetails with the observation that pigs with Ebola may appear to be healthy).