Bats are Likely Source of Ebola Virus Infection

After thousands of people died from the raging ebola virus infection, we had better be prepared. We’d better know where it comes from and where it hides out, in order to help prevent a new outbreak. Here we’ll discuss the most likely vectors for ebola.

Sporadic outbreaks

Ebola is a strange virus because outbreaks have occurred sporadically over the last four decades. The first occurred in 1976 and killed 280 people in Zaire. The second one didn’t occur until 1994 in Gabon where it killed 31 people. Then the next year it killed over 300 people in Zaire and Gabon.

In 2001 through 2003, Ebola virus killed 253 people between Gabon and the Republic of the Congo. Between 2007 and 2009 the virus emerged again in the Republic of the Congo and killed another 201 people.

Then between 2013 and 2015, Ebola virus has killed over 11,200 people.

Similar filovirus outbreaks have also occurred in between these – such as the Sudan virus. Nevertheless, it seems that the deadly Zaire ebolavirus will occur often many years apart.

Where does Ebola hideout in between outbreaks?

Since the Ebola outbreak of Africa has calmed down, researchers have been searching for two important factors of Ebola transmission: First, how is Ebola transmitted to humans? And secondly, where Ebola does go between outbreaks?

Both of these are considered vectors: A vector is a source of transmission as well as a reservoir.

Researchers have combed the environment of Africa and Asia to discover the possible vectors and reservoirs.

What have they found?

These scientists have found that Ebola – like a number of other viruses – seems to be transmitted through certain species of bats.

This spring a team of international researchers from around the world, in association with the University of Zambia, reported Ebola among fruit bats – species name Eidolon helvum. They took 748 blood samples from live bats, and found that 71 of the blood samples contained antibodies to several species of ebolaviruses – notably the Zaire ebolavirus that killed thousands of people last year.

They also found antibodies to the Reston ebolavirus – another variety of Ebola virus – found in pigs in Asia.

They also found that the recent Ebola outbreak was timed with bats being infected with a new family of viruses:

“Interestingly, the transition of filovirus species causing outbreaks in Central and West Africa during 2005-2014 seemed to be synchronized with the change of the serologically dominant virus species in these bats.”

More recently, an international team of researchers affiliated with the United Nations most recently sampled 464 bats of 21 species. They found that multiple species had genetic evidence of harboring the Reston Ebola virus.

These included the species, Miniopterus schreibersii, M. australis, C. brachyotis and Acerodon jubatus. They found the later bat contained antibodies to Ebola.

Many people in rural West Africa come into contact with bats. Some are bitten, but nearly half of those surveyed in rural Ghana by a team of researchers had eaten bat meat.

Bats can also harbor other dangerous viruses

Furthermore, bats have also been known to be vectors of other dangerous viruses, including Marburg, SARS, MERS and others.

While not many people are bitten, many animals are bitten by bats. Then the meats of these animals are eaten.

Ebola relies upon a unique weakening of the immune system in order to have its way. This means the first vector will typically have to have a weakened immune system in order to contract the virus. While many animals – including bats – will not typically show any symptoms, should their immunity weaken, the virus can take over, and increase in strength.

Once it is strengthened, the virus can then infect others, killing many as was shown in West Africa.

Of course, the research continues, but we can conclude that thus far, the most likely vector of Ebola is the eating of bat meat or the eating of bush meat from animals that the bats have bitten. The reason why eating infected bush meat or bats is the most likely vector – more likely than being bitten by a fruit bat – is because the Ebola virus needs a perfect storm-like combination of circumstances: The animal’s or human’s immunity must be weakened to the point where the virus can become stronger and infect the body.

The least likely, but also a possible vector – is from the being bitten by a bat. Still, this is quite possible.

The bottom line: To avoid further outbreaks of Ebola, people need to refrain from eating bats or animals that could have been bitten by fruit bats.

This conclusion was furthered by the researchers from the University of Zambia:

“These data suggest the introduction of multiple species of filoviruses in the migratory bat population and point to the need for continued surveillance of filovirus infection of wild animals in sub-Saharan Africa, including hitherto nonendemic countries.”

This doesn’t mean we have to get paranoid about all bats or anything. Only a few species of fruit bats are carriers.  And bats are important pollinators that help plants produce fruits.

Staying away from bat meat and meats from animals that may be exposed to bats provides a measure of safety, however. So does keeping a strong and vibrant immune system.

REFERENCES

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The World Health Organization Ebola Factsheet.

Centers for Disease Control. 2014 Ebola Outbreak in West Africa – Case Counts