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RML scientists research tick-borne diseases in West Africa


Dr. Dave Safronetz, seated at the head of the table, and colleagues inspect rodents in Mali for Lassa fever virus.

By Carlotta Grandstaff

Dr. Tom Schwan preparing to work in the Mali lab. NIAID photos.

As a young man, Dr. Tom Schwan spent two years in Kenya, serving in the Peace Corps. Like many travelers and expatriates who live and work far from home, Schwan developed an affinity for his host country.

He eventually went on to earn a doctoral degree at UC Berkeley, and is now chief of the Laboratory of Zoonotic Pathogens at Rocky Mountain Laboratories in Hamilton, where he focuses his research on tick-borne diseases, such as relapsing fever.

In 2001, with decades of research experience behind him, and with a desire to bring his expertise to Africa, Schwan traveled to the West African country of Togo with a team of Swedish scientists to look for evidence of relapsing fever. But with no reliable roads or infrastructure, Schwan found Togo a near-impossible place in which to establish a field laboratory. Seeking an African venue in which he could share his experience, he learned that the National Institute of Allergy and Infectious Diseases (NIAID), the parent agency of RML, had established a laboratory in the landlocked West African country of Mali. The Malaria Research and Training Center, located in the Malian capital city of Bamako, is considered a model for research centers in developing countries in that its research of malaria and tropical medicine is planned, directed and executed by NIAID and local scientists. In 2007, the British medical journal, The Lancet, reported that relapsing fever was evident in Senegal. “That just reinforced that we needed to get something going,” said Schwan.

He made the first of his seven trips to Mali in December 2007, bringing a project that focused on twin goals: using the infrastructure that his NIAID colleagues had established in Mali to determine whether relapsing fever occurs there; and if so, figuring how to train Malian public health workers to place relapsing fever on the diagnostic radar along with malaria.

Relapsing fever is a bacterial infection transmitted by a soft-bodied tick; malaria is caused by the Plasmodium parasite, carried by the Anopheles mosquito, and both share similar symptoms of high fever, shaking chills, muscle aches and general flu-like misery.

The treatments for each disease are vastly different, however. Relapsing fever is treated with antibiotics, malaria with various quinine derivatives.

Schwan believes that there well may be people suffering from relapsing fever who are mistakenly diagnosed with, and treated for malaria, a disease that is rife in Africa. Treating patients for malaria if they are actually suffering from misdiagnosed relapsing fever will do nothing to eliminate the infection.

Tick-borne relapsing fever is caused by the Borrelia crocidurae spirochete, a flexible, spiral-shaped bacterium transmitted by the Ornithodoros sonrai tick. In Africa, the tick’s blood hosts are rodents and shrews that are so common and widespread they can be found living alongside humans in their homes.

As Schwan and his colleagues were busy trapping rodents to test their blood for evidence of infection from the disease-carrying ticks, another RML scientist, Dr. Dave Safronetz, was preparing his own trip to Mali. In 2009, a British engineer and aid worker was taken ill and evacuated from Mali to London, where he subsequently died of the Lassa virus which he likely had contracted in Mali – though the virus had never been isolated in that country.

Lassa virus was first described in the late 1960s. Between a quarter and a half million cases are reported annually in Africa, most of which – 80% – are asymptomatic. The remainder progress to severe illness and about 1% of those – about 5,000 cases annually – are fatal.

With a research background in hanta viruses, with an NIAID lab already in place, and with his colleague having established connections in Mali, Safronetz, who earned his doctorate at the University of Manitoba and now works in RML’s Laboratory of Virology, was well placed to launch a research project to find evidence of Lassa virus in Mali.

Like tick-born relapsing fever, Lassa virus also is carried by Mastomys rodents – although transmitted to humans by an entirely different mechanism. Where relapsing fever is transmitted by a tick bite, Lassa is transmitted in much the same manner as hanta viruses: via the aerosolized feces and urine of infected rodents, though it also can be transmitted by direct contact and by eating a contaminated rodent.

Lassa virus is characterized by a set of varied and non-specific symptoms, including back, throat and abdominal pain, vomiting and diarrhea, making clinical diagnosis difficult.

The collaborative research projects established by Schwan and Safronetz yielded hundreds of rodents, trapped by colleagues in villages and tested for both diseases. Schwan and his team took blood samples; Safronetz and his group took tissue samples. Of the rodents tested, one-fourth tested positive for Lassa virus, which enabled Safronetz to prove that Lassa virus did, in fact, exist in southern Mali where they had set up surveillance. Schwan’s group, meanwhile, had determined that 17% of the ticks they examined carried active infection, and 40% of the rodents in one area were shown to have prior infection. Schwan’s research group also needed to identify the genus and species of the infected rodents. They captured 14 distinct species of small mammals, and confirmed evidence of infection in five species.

In January of this year, Schwan made his seventh trip to Mali, with plans to make one or two more to finish up his research. Safronetz made his fourth trip last March. All was going well. Both scientists were making measurable progress in a country that, on the surface at least, appeared stable and democratic, and which benefited from a significant NIAID presence and research investment.

Then, on March 22, days after Safronetz departed from Africa, junior officers in Mali President Amadou Toumani Toure’s military seized control of the capital city and ousted the two-term, democratically elected leader as he was completing the final weeks of his last term in office.

According to news agencies Reuters and the BBC, the unrest, which came as a surprise to some, had its roots in the dictatorship of former Libyan leader Moammar Qadaffi.

Mali is a huge, sprawling, puzzle-piece of a country, oddly right-angled. It’s northern half – roughly twice the size of Texas – is home to the Tuaregs, a nomadic ethnic group who, largely neglected by the central government in Bamako since independence from France in 1960, joined military forces with Qadaffi in the early 1970s. After Qadaffi’s regime collapsed, the heavily-armed Tuaregs began returning home to agitate for an independent northern homeland. The Tuareg uprisings began last January and were largely concentrated in the Tuareg’s Saharan homeland. In the far-off capital of Bamako, President Toure’s junior officers and low-ranking soldiers, angry at his failure to deal with the uprising, seized control and ousted the leader.

Armed unrest in an African country is not likely to have registered on anyone’s radar in the Bitterroot Valley, except, of course, for Schwan, and Safronetz, and their RML colleagues, whose research projects are now somewhat in limbo. The Mali situation is chaotic. Despite his email communications, it’s impossible to ascertain from Schwan’s neat and sunny office on South Fourth Street exactly what is happening to the project, his colleagues and his friends on the other side of the world. He checks his email regularly, but since coups tend not to unfold on a predictable schedule, all he’s learned is that last week the American embassy in Bamako was closed, but on the day of this interview, May 7, it was open.

What Malian political chaos means to the RML researchers and their projects is, of course, unclear. Both scientists say that if they cannot return to Mali now or anytime soon, they can probably wrap up their projects with the information they’ve gleaned in a combined total of eight years of Malian fieldwork. But that doesn’t prevent them from worrying about the friends and contacts they’ve made over the years.

The infrastructure NIAID established in Mali remains in place, he says. “The concern now is trying to get hold of the people. All those folks have families. I hope all our friends and colleagues are OK.”

Schwan has been in email contact with one local colleague in particular. Since the March 22 coup, Ousmane Maiga has replied to Schwan’s emails, though his responses are a bit cryptic and Schwan is not sure why. It worries him a bit.

For now, Schwan has plenty of work to keep his research group busy. They are breeding Ornithodoros sonrai ticks at RML that scientists collected and shipped back from Mali. Safronetz and his team also collected and shipped back samples of Lassa virus collected in the field.

“Everyone’s hands are tied right now,” says Schwan. Safronetz adds, “I think we certainly raised awareness that Lassa is in Mali. If everything stopped right now, at least the message is out.”

Schwan hasn’t given up on the idea of returning to Mali someday. Though in one sense, his team could finish the project with the evidence they’ve gathered to date, in another, the work remains unfinished. “I still have a fantasy of being able to train Malian scientists to identify spirochetes so that people getting relapsing fever can be diagnosed and given the proper medical treatment.”

One Response to RML scientists research tick-borne diseases in West Africa
  1. Ousmane
    August 7, 2012 | 5:05 pm

    Ticks will suffer

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