DENVER – Dr. Michelle Barron, medical director of infection prevention and control at the University of Colorado UCHealth Hospital, received an unusual call last month from the microbiology lab: confirmation of the third case of trench fever this year, a condition rare transmitted by body lice that tormented soldiers during World War I
Barron’s epidemiological training began.
“Two is always an outbreak, and then when we find a third, that’s fine, we clearly have something to do,” Barron recalled.
Barron, who said he had never seen a case in his 20 years here before, contacted state public health officials, who issued a notice Thursday and said a fourth person had been identified with a suspicious case. They asked doctors to be on the lookout for additional cases.
Trench fever is characterized by recurrent fever, bone pain (particularly in the shins), headache, nausea, vomiting, and general malaise. Some of those infected may develop skin lesions or a life-threatening infection of the heart valves.
The condition is caused by the Bartonella quintana bacteria, a close relative of the insect that causes cat scratch fever. Their colonies live in the digestive systems of body lice and are excreted in their feces. Insects can enter the body through a scratch on the skin or through the eyes or nose. Dry lice feces can be infectious for up to 12 months.
Trench fever is most often diagnosed among people who are homeless or who live in conditions where good hygiene is difficult. Those with compromised immune systems are particularly at risk.
Public health officials are trying to find a common thread among the four cases identified so far in Colorado. They happened months apart, and patients seem to have no connection other than homeless people in the Denver area.
Other cases of the disease may have been overlooked. This outbreak occurs, after all, at a time when much attention is diverted to the coronavirus pandemic. But the economic consequences of that crisis could be fueling the outbreak of a disease that thrives on difficulties.
Trench fever can be an easy diagnosis to miss, Barron said. Patients often have other health problems that could explain their symptoms, and doctors will try to rule out the most common causes before considering a rare one.
Also, bacteria grow very slowly in laboratory cultures – it can take up to 21 days, and laboratories generally discard cultures after seven days. Barron said the bacteria in two of the confirmed cases grew just before the cell cultures were discarded.
Doctors often treat the symptoms of a disease like trench fever with antibiotics. If the patient is cured, tests may not be done to determine the organism causing the disease, said Dr. Kristy Murray, an infectious disease specialist at Baylor College of Medicine and Texas Children’s Hospital in Houston.
“With this particular disease, unless you work in an environment where you are with homeless people all the time, you are not thinking about it or looking for it,” he said. “It’s very weird.”
However, in recent years, outbreaks have occurred in the homeless camps in San Francisco and Seattle.
Barry Pittendrigh, an entomologist at Michigan State University who was part of an international collaboration studying lice that causes trench fever, said that lice can also transmit the bacteria, but his immune system is strong enough to keep it down. control. Body lice live on clothing and turn on and off to feed on the body. His immune system is not that strong, he said, so bacteria can flourish.
“We see scenarios in which social crises occur (wars, economic recession, displacement of people), when there is the possibility that we have hygiene problems that, in turn, these lice populations take off and contract these diseases,” he said. Pittendrigh. said.
An increase in body lice occurred during the 2008 recession, he said, and before that, during the Great Depression and the two world wars. The current economic and health disruption caused by the COVID-19 pandemic could lead to yet another increase.
As public health agencies struggle with the coronavirus, fewer resources remain to locate outbreaks of other infectious diseases.
Colorado is committed to fighting both problems, said state health department spokeswoman Deanna Herbert. “We continue to increase COVID-19 response personnel, allowing us to balance other outbreaks and needs with the response to the global pandemic,” she wrote in an email. “Climbing to the size we have is a tremendous task, but we have a staff that is absolutely committed to being as responsive as possible to the needs of all of Colorado.”
Murray said an outbreak can often be interrupted by disclosure to homeless shelters and other groups that provide services to those living on the street. Mobile showers or the offer to wash or replace your clothes can help. Body lice can be killed by washing and drying clothes at high temperatures, at least 130 degrees Fahrenheit.
The pesticide permethrin can also be used to treat clothing, bedding, and backpacks to prevent lice infestation. However, most people don’t need to worry: According to the Federal Centers for Disease Control and Prevention, the infestation is unlikely to persist in anyone who bathes regularly and changes to clean clothes and bedding every night. weeks.
Still, trench fever has been considered a reemerging disease since the 1990s.
“Old infectious diseases always have the potential to come back,” Barron said. “Although we live in a society that we consider to be very modern and very safe on many levels, these organisms, at the end of the day, have been here longer than us and plan to survive.”
