Jakarta Post: Imminent risk of disease from live animal markets

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Imminent risk of disease from live animal markets

 

Karmele Llano Sanchez, Jakarta

 

An article published last July in Emerging Infectious Diseases reports on

the significant impact that the wildlife trade and live animal markets are

having on human health worldwide, in particular Asia.

 

The large population on this continent arguably increases the likelihood of

a pandemic occurring. It is in this continent also where the population is

at higher risk of contracting animal-borne diseases due to the encroachment

of humans into wildlife habitats, and the presence of animal markets where

animal products and live animals are on sale.

 

 

Presently, an outbreak of H5N1 type A influenza virus (bird flu) has alerted

human health authorities in Indonesia. This zoonosis (an animal disease

capable of being transmitted to humans) has already cost the lives of dozens

of people. However, the most threatening aspect is the possibility that many

other zoonotic pathogens could be covertly infecting people basically

because they are difficult to diagnose by physicians.

 

 

This highlights the question of where these emerging pathogens are hidden

and what causes them to emerge. According to Lonnie King et al,

three-quarters of emerging human diseases over the past two to three decades

have been animal-borne, and the future will probably bring many more such

outbreaks.

 

 

In addition, the threat of these diseases spreading quickly worldwide is

reasonably high due to contemporary global transport patterns: planes,

ships, people and animals carry infections in every direction.

 

 

Animal health has broad implications, ranging from the health of individual

animals, human health and global security. Animal diseases have implications

not only for the global food supply but also for human health directly due

to the existence of animal borne diseases transmissible to humans

(zoonoses).

 

 

The pool of infectious pathogens shared between animals in a market will not

stay confined to these locations. To the contrary, these animals and their

pathogens will be transported to other areas, locally and nationally, and

even internationally when animals are smuggled outside of the country.

 

 

This not only threatens people but also wildlife, when, for instance, they

are eventually released by the owners because they are no longer wanted, or

when they escape and become a threat to local wildlife.

 

 

The likelihood of disease transmission is also increased when animals are

submitted to unnatural conditions causing high stress levels.

 

 

Wild animals suffer much stress when they are captured and transported, then

forced into a completely unknown environment, surrounded by their most

dangerous predator: humans. They are also offered for sale in cramped cages

with no space to even stretch their bodies.

 

 

At the same time, this stress renders their immune system less effective,

making them more prone to infections for which they are not a natural host.

 

 

Pathogens for which humans become new hosts are more hazardous while human

immunity does not yet posses the ability to fight them.

 

 

Some estimations of the numbers of wild animals traded annually worldwide

includes approximately 40,000 live primates, 4 million live birds, 640,000

live reptiles, and 350 million live tropical fish. According to one report,

in a single market in North Sulawesi up to 90,000 mammals are sold per year.

 

 

 

Over the last 25 years, more than 35 diseases have emerged. In a list of

1,415 human pathogens, 61 percent are known to be zoonotic, and

multiple-host pathogens are twice as likely to be associated with emerging

infectious diseases in humans. As much as 77 percent of pathogens found in

livestock are shared with other host species.

 

 

The rash of emerging or reemerging livestock disease outbreaks around the

world since the mid 1990s, including bovine spongiform encephalopathy,

foot-and-mouth disease, avian influenza, swine fever, and other diseases,

has cost the world economy $80 billion.

 

 

Efforts to control the spread of avian influenza in Asian countries since

2003 has required the killing of about 140 million chickens. In order to

keep up with an increasing population and growth in demand for protein,

countries such as Indonesia will have to increase livestock production which

will increase the risk of livestock disease outbreaks. Following this

tendency, it is very likely that these infections will be linked to wild

animals.

 

 

In July of this year, studies reported the first case of simian foamy virus

(SFV) infection, a non-human primate-borne disease, in a person with known

exposure to free-ranging Indonesian macaques in an eco-tourism monkey

attraction in Bali.

 

 

Alarm warns foreign tourists not to have close contact with macaques in

these kinds of premises. However, no risk awareness is raised for local

people who keep these monkeys as pets, or who sell them in markets. In all

the animal markets of Jakarta and in other large cities in Java and other

islands, macaques are commonly seen on sale either as pets or for human

consumption. No animal disease control is carried out and no authority warns

people of the risk of transmission of diseases.

 

 

The poor hygienic conditions in these markets means a risk for sellers,

buyers, visitors and the entire environment. The close contact between

people and animals and their diseases in the context of any animal market

is, arguably, a potential risk for zoonoses to emerge.

 

 

All these wild animals harboring pathogens would not be a hazard to human

beings at all if they were left alone in their natural habitats far away

from humans. It's only when humans cross the barrier and stand in the way of

these pathogens that the risk of new disease emerges.

 

 

Emerging Infectious Disease reports that some studies have shown that

closing down retail poultry markets in Hong Kong for one day per month

reduced the rate of H9N2 avian influenza virus in market birds. In the same

terms, it seems reasonable to think that closing down animal markets would

have an analogous effect in the Indonesian context.