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Could Rift Valley fever be a weapon of mass destruction? An insidious insect-animal-people infection loop explored

The Fifth Plague: Livestock Disease, woodcut by Gustave Doré, 1866 (public domain, via Wikimedia Commons).

Anthrax, bird flu , Ebola, HIV-AIDS, H1N1, H5N1, influenza, Rift Valley fever, SARS: What are the disease links between people, animals and environments? And what are we doing to protect ourselves against the next outbreak of a deadly infectious disease? A series being published in the Huffington Post is exploring such ‘living weapons’ and our preparedness, or lack thereof, in dealing with them. Keeping an eye on livestock diseases, experts agree, is a major way to prevent deadly outbreaks of human diseases. And these animal-human disease links, they say, are under-appreciated and under-funded.

Take Rift Valley fever, a disease transmitted between mosquitoes, livestock and people in Africa. Although considered by many experts to be a potential bioterrorist weapon, it remains underfunded.

As Lynne Peeples of the Huffington Post reports:

This emphasis on coordination among medical, veterinary and environmental health scientists, reflecting the global “One Health” movement, could also be employed in the development of vaccines and treatments for bioterror threats.

Rift Valley fever virus is a prime candidate for such collaboration, says BioProtection Systems’ [Ramond] Flick, an expert on emerging infectious disease, which can afflict both animals and humans. Creating a livestock vaccine would reduce the risk of human infection.

However, because the disease is not considered a priority human bioterrorism agent by the government, research funding is low. Jason McDonald, a CDC spokesperson, explains the agency’s exclusion of Rift Valley: humans typically contract the virus through bites of infected mosquitoes and just 1 percent of these victims die.

Flick disagrees.

The public’s current awareness of Rift Valley fever and its perception of the West Nile virus threat before 1999 are strikingly similar, he says. West Nile had not been given much thought before it cropped up in New York City. Within a few years it had spread across the country.

Flick warns of even more devastating consequences with the relatively unknown bug. More mosquito species can carry Rift Valley than West Nile. It is also more virulent. And according to research in Arabia and Africa, the fatality rate may actually be increasing, killing more than 30 percent of people infected during recent outbreaks. Further, there does appear to be potential for human-to-human transmission.’

Scientists at the International Livestock Research Institute (ILRI) have been working with partner organizations in eastern and southern Africa to better understand the spread of Rift Valley fever. They are developing a toolkit that will help decision-makers make timely and appropriate interventions to prevent the disease from jumping from cattle to the poor people who rear them. The toolkit includes advice on the conditions that suit the Rift Valley fever virus infecting cattle populations (e.g., following unusually heavy rains northern Kenya and other parts of the Horn’s drylands), at which point disease control agents should begin surveillance to diagnose and stop the spread disease in the infected animals before it has time to begin infecting human populations.

Efforts to better align the work of organizations researching Rift Valley fever were the focus this month (Feb 2012) of a workshop organized and hosted by ILRI at its Nairobi headquarters. Watch for a forthcoming post on the ILRI New Blog on that workshop and what it achieved.

The urgency of adopting a ‘one health’ approach to disease control is highlighted by the Huffington Post‘s Lynne Peeples.

‘. . . Biological weapons have a long and sordid history, from catapulting infected corpses to dropping bombs of plague-infected fleas. But what if a biological weapon were being developed and studied by scientists that had the potential to kill not a battalion or a city, but 150 million people? According to some public health and defense officials, that is exactly what we’re facing, following the cultivation of a highly contagious form of H5N1—a lethal bug better known as bird flu. The contagion, they fear, could escape the lab or its recipe could land in the wrong hands.

. . . A super flu is just one of a growing list of potential pandemics that could develop in the near future, either as a result of terrorism, of superbugs leaping from animals to humans, or both. In fact, nearly 80 percent of the bioterrorism agents recognized by the U.S. government started in animals. . . . And nature will spawn new agents continuously.’

‘This means a terrorist may need few tools, little training, minimal money and no published blueprint to harvest a superbug and then unleash it in food, water, air or via insect vectors such as fleas or mosquitos. . . .

The overlap of bioterrorism agents and emerging infectious disease also means that officials could defend against biological attacks and natural outbreaks in tandem.’

‘. . . Yet federal funding to prevent and respond to bioterrorism is plummeting. The U.S. Centers for Disease Control and Prevention’s biodefense budget peaked in 2005 at about $1.2 billion. The 2012 budget is down to $800 million, with state and local programs—the country’s first line of defense—absorbing some of the most significant cuts. . . . The U.S. “remains largely unprepared for a large-scale bioterrorism attack or deadly disease outbreak.”

. . . Meanwhile, nature knows no rules or regulations and continues to create new viruses and alter old ones. And because animal-borne diseases may need no help spilling over into humans, outbreak investigations could easily confuse intentional and natural outbreaks.

“The government spends a lot of money developing biosensors,” says Princeton’s Kahn, referring to air sampling surveillance and other sophisticated systems. “But I would argue the best ones are flying around,” or in this case, hanging out on farms.

Zoos can be particularly good sources of sentinels, she adds, as they house a wide array of animals from around the world with different levels of susceptibility. Most zoos are also located near densely populated urban centers, which tend to be terrorism “hot spots.”

“There’s a possibility that the high-tech tools are not even in the right place,” says Rabinowitz. “By being constantly aware of new events in animals as well as in humans and the environment, we’re more likely to pick up a new threat.”. . .

This emphasis on coordination among medical, veterinary and environmental health scientists, reflecting the global “One Health” movement, could also be employed in the development of vaccines and treatments for bioterror threats. . . .

Researchers have discovered an average of 15 to 20 previously unknown diseases in each of the past few decades, including incurable diseases like HIV/AIDS, ebola and SARS, with new pathogens likely to emerge and spread faster due to the global population’s increasing size and mobility.’

‘. . . The ability to detect and identify diseases as they initially emerge can go a long way in thwarting an outbreak, [Scott Lillibridge] says. It can provide the time to prepare, including upgrading quarantines at the border, researching a vaccine and identifying what drugs might successfully combat the infection.

‘”A couple weeks can be critical,” says Lillibridge. “It can make an administration look foolish or like they’re in control.”

‘Overall, the U.S. government spent approximately $60 billion on biodefense from 2001 to 2009. Only 2 percent of that was dedicated to preventive measures such as programs to discover and reduce biological threats overseas, according to Koblentz.

To protect Americans, we must look at what is going on in the rest of the world,” says Khan.

ANSER’s Gursky, recently returned from hosting a NATO meeting in Central Europe: “The most important strategy is to build up the capabilities that we share, which means reaching across borders and politics,” she says.’

‘Coalescing efforts might also allow the government to do more with less. “We’re looking at not only man being a terrorist, but nature can be a terrorist as well,” says Henderson. “The natural occurrence of a disease gives us similar problems, so whatever we’re doing to prepare for one, prepares us for the other.”‘

Read the whole article, by Lynne Peeples, in the Huffington Post: Bioterrorism funding withers as death germs thrive in labs, nature, 10 Feb 2012; this article is part of a series, ‘The Infection Loop,’ investigating the complex links between human, animal and environment.

Read more on ILRI’s News Blog and Clippings Blog about recent research advances in better control of Rift Valley fever.

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