Pigs Barking Blood
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As H5N1 was emerging in Hong Kong in 1997 more than ten million acres of virgin forest were burning in Borneo and Sumatra. The resulting haze is thought to have caused a mass migration of fruit bats searching for food. Forced out of the forests and into areas of human cultivation, some of these so-called flying foxes nested in mango trees overlying huge Malaysian pig farms. The flying foxes dribbled urine and half-eaten fruit slobbered with saliva into the pig pens.905 The bat urine and saliva were both later found to contain a virus906 —named the Nipah virus, after the village with the first human fatality. That virus was harmless to the fruit bats, but far from harmless to everyone else.907
The pigs developed an explosive cough that became known as the “one-mile cough,” because the violent hacking could be heard from far away. The disease was called “barking pig syndrome,” after the unusual, loud barking cough.908 Pigs started coughing blood909 and developing neurological symptoms. Sows pressed their heads against the walls, started twitching, became paralyzed, or seized into spasms. Many died within 24 hours.910
Using pigs as its conduit, the virus turned its attention to others. Almost every animal in the vicinity started falling ill—other farm animals like goats and sheep, companion animals like dogs, cats, and horses, and wild animals like deer fell into fatal respiratory distress.911 Human animals were no exception. People broke out in high fevers and headaches as their brains began to swell. Many started to convulse. Those who went into a coma never woke up.912 On autopsy, their brains and lungs were swollen with fluid.913
The disease erupted in the northern part of the Malaysian peninsula, but ultimately swept nationwide on a seven-month rampage thanks to long-distance animal transport.914 “A hundred years ago, the Nipah virus would have simply emerged and died out,” the Thai Minister of Public Health explained; “instead it was transmitted to pigs and amplified. With modern agriculture, the pigs are transported long distances to slaughter. And the virus goes with them.”915 A one-mile cough is still only a one-mile cough in a country that is almost 5,000 miles around.916
The Nipah virus was finally stamped out by stamping out much of the Malaysian pig population.917 Pig farmers started the cull, beating the animals to death with batons, but the Malaysian army needed to come in to finish the job, killing more than one million pigs.918
The virus turned out to be one of the deadliest of human pathogens, killing 40% of those infected, a toll that propelled it onto the U.S. list of potential bioterrorism agents.919 Nipah is also noted for its “intriguing ability” to cause relapsing brain infections in some survivors920 many months after initial exposure.921 Even more concerning, a 2004 resurgence of Nipah virus in Bangladesh showed a case fatality rate on par with Ebola—75%—and showed evidence of human-to-human transmission.922
The surfacing of the Nipah virus demonstrates how slash-and-burn deforestation may contribute to disease emergence in unexpected ways. Remote rainforest intrusions can bring humans into contact with viruses they had never before been in contact with, or, as in the case of Nipah, it can bring the new viruses out to us. One zoologist quipped “Nipah appears to be a case of the bats getting some payback.”923 This may not have been possible without collusion from the pig industry.
It is likely no coincidence that the Nipah outbreak began on one of the largest pig farms in the country.924 Raising pigs is not new in Malaysia, but intensive industrial production is. The Leong Seng Nam farm, where the epidemic broke out, confined more than 30,000 pigs. The Nipah virus, like all contagious respiratory diseases, is a density-dependent pathogen,925 requiring a certain threshold density of susceptible individuals to spread, persist, and erupt from within a population.926 Scientists suspect it may have taken more than a year of circulating in this unnaturally massive herd before it learned to fully adapt and mutate into a strain that explodes into other mammals.927 “Without these large, intensively managed pig farms in Malaysia,” the director of the Consortium for Conservation Medicine said, “it would have been extremely difficult for the virus to emerge.”928
China is the world’s largest producer of pork.929 Much of the pig production is concentrated in the Sichuan province, which in 2005 suffered an unprecedented outbreak in scope and lethality of Streptococcus suis, a newly emerging zoonotic pig pathogen.930 Strep. suis is a common cause of meningitis in intensively farmed pigs worldwide931 and presents most often as meningitis in people as well,932 particularly those who butcher infected pigs or later handle infected pork products.933 Due to involvement of the auditory nerves connecting the inner ears to the brain, half of the human survivors become deaf.934
The World Health Organization reported that it had never seen so virulent a strain935 and blamed intensive confinement conditions as a predisposing factor in its sudden emergence, given the stress-induced suppression of the pigs’ immune systems.936 The USDA explains that this bacteria can exist as a harmless component of a pig’s normal bacterial flora, but stress due to factors like crowding and poor ventilation can drop the animal’s defenses long enough for the bacteria to become invasive and cause disease.937 China’s Assistant Minister of Commerce admitted that the disease was “found to have direct links with the foul environment for raising pigs.”938 The disease can spread through respiratory droplets or directly via contact with contaminated blood on improperly sterilized castration scalpels, tooth-cutting pliers, or tail-docking knives.939 China boasts an estimated 14,000 confined animal feeding operations (CAFOs),940 colloquially known as factory farms, which have stocking densities conducive to the emergence and spread of disease.941
The United States is the world’s second-largest pork producer,942 and Strep. suis infection is also an emerging pathogen in North American pig production, especially in intensive confinement settings.943 According to the Journal of Swine Health and Production, human cases of meningitis in North America are likely underdiagnosed and mis-identified944 due to the lack of adequate surveillance.945 The WHO encourages careful pork preparation,946 and North American agriculture officials urge Strep. suis disease awareness for people “who work in pig barns, processing plants, as well as in the home kitchen….”947
The first human case of Strep. suis was not in Asia or in the United States, however, but in Europe. The Dutch pig belt, extending into parts of neighboring Belgium and Germany, has the densest population of pigs in the world, more than 20,000 per square mile. This region has been hit with major epidemics within recent years of hog cholera and foot and mouth disease, leading to the destruction of millions of animals. “With more and more pigs being raised intensively to satisfy Europe’s lust for cheap pork, epidemics are inevitable,” wrote New Scientist’s Europe Correspondent. “And the hogs may not be the only ones to get sick.”948
Even industry groups like the American Association of Swine Veterinarians blame “[e]merging livestock production systems, particularly where they involve increased intensification” as a main reason why zoonotic diseases are of increasing concern. These intensive systems, in addition to their high population density, “may also generate pathogen build-ups or impair the capacity of animals to withstand infectious agents.”949 Increasing consumer demand for animal products worldwide over the past few decades has led to a global explosion in massive animal agriculture operations which have come to play a key role in the Third Age of emerging human disease.950