A
Publication of
The University of Montana
Spring 2006
Going Global: UM's international efforts link Montana to the world
Speeding Glaciers: UM researchers study movement of ice rivers
Ranching Human Lice: This story will make you itch
An Angry Earth: Researcher delves into terrible Pakistan quake
Research View is published twice a year by the offices of the Vice President for Research and Development and University Relations at The University of Montana. Send questions, comments or suggestions to Rita Munzenrider, managing editor, 327 Brantly Hall, Missoula, MT 59812, or call (406) 243-4824. Production manager and designer is Cary Shimek. Contributing editors and writers are Brianne Burrowes, Patia Stephens, Shimek and Cory Walsh. The photographer is Todd Goodrich. For more information about UM research, call Judy Fredenberg in the Office of the Vice President for Research and Development at (406) 243-6670.
BIOLOGICAL SCIENCES
Ranching
Human Lice
Warning:
This story will make you itch
Feel that tiny prickle between your skin and clothes? Maybe it’s just leftover soap drying from your morning shower. Perhaps a stray thread is poking your skin.
Or maybe it’s a sesame seed-sized insect scuttling around on tiny clawed legs. This crawly critter, the body louse, loves the humid 86-degree environment under your shirt or beltline, and it wants to feed on your blood using its piercing mouthparts. It might even excrete dark red feces onto your skin before cementing its eggs -- called nits -- to your body hair or clothing.
And if you aren’t nitpicky about finding all the eggs and improving your personal hygiene, there will be more. Lots more. Probably a full-blown infestation.
Sound disgusting? Well, it gets worse. Body lice are known to carry three human diseases -- typhus, relapsing fever and trench fever. It’s said that during World War I, lice-borne disease killed more men than bullets. Only influenza killed more soldiers in the trenches.
These days in the Western World, head lice still prey upon children, while their slightly larger cousins, body lice, sometimes crop up among homeless alcoholics and AIDS patients. Besides inner-city environments, louse-transmitted trench fever also appears across wide swaths of Mexico and Africa.
UM Professor Mike Minnick, a medical microbiologist, runs one of three labs in the world to study body lice and the pathogens they can carry -- especially trench fever. He says the malady is caused by a bacterium called Bartonella quintana, one of a group of pathogens that he has studied for 15 years.
Characterized by high fever, forehead pain, general sluggishness and aching shins, trench fever can kill people living in unhealthy conditions or with compromised immune systems. A microscope reveals swarms of Bartonella in the blood of an infected person.
“This bacterium is able to live in both lice and people, which are two tremendously different environments,” Minnick says. “So we want to know why and how they can do this. We also want to see how the bacterium interacts with the louse, how the louse transmits the pathogen and where the bacterium lives inside the louse … those types of questions.”
Specifically, his lab studies a family of genes in the bacterium involved in acquiring iron from the environment, as well as the mechanisms that switch these genes on and off. Find a way to switch off the right genes at the right time, and you stop lice from transmitting trench fever or other louse-borne agents.
It’s a long way off, Minnick says, but unraveling the complexities of this gene family could lead to a trench fever vaccine.
But first one needs a fairly large sample of bacterial ribonucleic acid (RNA) from the guts of infected lice to study. This means growing human body lice in the lab, and that’s where Minnick’s postdoctoral student Jim Battisti comes in.
“I kind of feel like a louse rancher,” the soft-spoken Battisti says. “They are hard to keep going because you have to feed them six out of seven days a week, and every day it takes about an hour to feed them.”
The researchers use a strain of lice that was adapted in the 1940s to feed on rabbits instead of humans. The lice live in an incubator resembling a small refrigerator. Inside the device, warm and humid conditions mimic those found between human clothing and skin.
The insects spend their 40-day lives crawling, growing and molting on little pieces of corduroy cloth inside the incubator. The lice progress from nits (eggs) through three immature nymphal stages before finally crawling out of their old skins to become adults.
Battisti feeds the lice using two rabbits he has laboriously trained to lie still on their backs on a foam pillow while strapped firmly in an apparatus of his own design. He places the lice onto shaved areas on the rabbits’ stomachs, and he says the feedings are harmless.
One problem with the incubator is the smell, Battisti says. Collected lice smell horrible (which is why someone infested with lice often smells). They also defecate a lot of digested blood -- leaving dark reddish stains -- which can turn the cloth squares they live on into a bacterial soup that’s even bad for lice. Battisti has learned to pick up the cloth squares (he calls them “blankies”), dry them slightly and then shake the lice free when he does a cleaning.
It’s a dirty job that sometimes has consequences.
“They’ve gotten on me, and I’ve taken them home,” Battisti says. “At first I was really creeped out -- and the smell -- but if you find one on you, you just kill it.” Minnick agreed: “Yeah, I’ve been bitten.
Everyone that works with an insect model has been bitten by that insect.”
Battisti says it took a year and a half of hard work and trial and error to create the thousands-strong lice breeding population for the lab, but now he admits to a certain fondness for the tiny blood-sucking critters under his care.
“I thought about feeding them human blood for a while,” he says with a laugh. “I considered taking them home on the weekends and just giving them a little meal on me rather than having to drive up to campus. Didn’t of course.”
To study the interactions between Bartonella bacteria and lice, you need to get the microorganisms into the insects. This is usually done by injecting rabbits with Bartonella quintana and letting the lice feed on the infected animal.
“But that means this rabbit you’ve trained forever to lie on its back for feedings is infected and you can’t use it anymore,” Battisti said. So they have developed a system to feed the lice infected human blood through an artificial membrane.
It hasn’t been a total success. Newborn nymph lice will use a membrane, but older lice won’t go for it. They prefer rabbit.
“It’s these spoiled adults -- the ones we really want to drink a bellyful – that won’t use our artificial system,” Minnick says. “We have tried all kinds of different things for membranes. We even tried lambskin condoms, but so far no luck.”
Battisti says the nymphs they coaxed into drinking infected blood don’t provide a large enough sample for their experiments. “So what we are still working on is finding a way to get large amounts of bacteria into adult lice.”
Though the lice project grabs attention, it’s actually only part of the work funded by a prestigious National Institutes of Health grant. Minnick says they are studying how a gene family in Bartonella bacteria uses iron, an essential nutrient, and they are delving into the regulatory mechanisms of gene expression.
“We are taking a holistic approach,” he says. “If we can find how these genes are binding an essential nutrient, we may be able to block a receptor and find a cure for that particular disease.”
The seven people in Minnick’s lab also work on a biodefense project involving Q fever -- an illness that can make people extremely sick for weeks and can lead to hepatitis and even lethal inflammation of heart valves. Q fever is caused by a bacterium that could be weaponized by terrorists, so the lab is helping to develop diagnostic and therapeutic techniques and potentially a vaccine for the pathogen.
Minnick says their partners on the Q fever effort include scientists at Montana State University and Rocky Mountain Labs in Hamilton. The effort is funded by the NIH Rocky Mountain Regional Center of Excellence based at Colorado State University.
While delving into bacterial genes and studying biodefense measures, Minnick and Battisti never expected to become experts on caring for human body lice.
“It’s kind of odd, but I have a blast,” Battisti says. “We have become one of the few places to do louse studies.”
“And now investigators from other parts of the country want to use our lice colony here for their experiments,” Minnick adds. “It’s pretty exciting.”
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| A virulent strain of Bartonella quintana bacteria |
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| The bacteria are grown in petri dishes. |
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| The lice ranchers: Jim Battisti (left) and Mike Minnick. At their feet is the incubator where the human body lice are housed, and Battisti holds a tray of cloth squares crawling with hundreds of the tiny bloodsuckers. |