Q: My daughter returned from a trip to the Dominican Republic and several of the people on the trip began having flu-like symptoms. One of the girls was evaluated for leptospirosis. What is this, and should I be concerned?
A: Leptospirosis is a bacterial infection caused by one of nine of the 21 subtypes of the bacteria Leptospira (only nine of these cause disease in humans). This bacteria infects many different types of animals (domesticated animals like sheep, swine, cattle, horses, goats and dogs as well as certain wild animals including certain rodents), which may have no symptoms from it or which may develop illness (it is estimated that up to 10 percent of infected dogs die from the disease). The bacteria is excreted in the animal’s urine, where it can then contaminate water or soil.
Humans may be exposed to the disease when they come in contact with the bacteria, either directly by contact with the animal’s urine or indirectly by contact with water or soil that has been contaminated (the bacteria can live in the contaminated water/soil for days to months), usually through cuts or abrasions compromising the person’s skin barrier, by contact with the person’s mucous membranes or eyes, or rarely by ingesting contaminated water. Given the method of transmission of this illness it is not surprising that risk factors for developing it include occupational exposure (such as to farmers, veterinarians, etc.) or exposure in adventurous people who spend time outdoors where infected animals may have spread the bacteria (such as hikers, people swimming in fresh water like ponds in the wilderness, etc.). The World Health Organization estimates that there are almost a million humans infected with Leptospira per year, and that it causes up to 50,000 deaths worldwide.
The initial symptoms of leptospirosis start a few days to a several weeks after exposure to the bacteria, and include ‘flu-like’ symptoms such as fever, shaking chills, muscle aches, headaches, cough, and sometimes gastrointestinal symptoms such as nausea/vomiting, diarrhea. Some patients develop eye symptoms (redness of the conjunctiva called conjunctival suffusion, which in this setting is very suspicious for leptospirosis). Over 90 percent of patient’s get better on their own, with resolution of symptoms and often not ever knowing that they had leptospirosis. However, a second phase of the illness, called Weil’s disease, may occur where the infection becomes severe and potentially compromises the function of the patient’s kidneys, liver, lungs or other body organs.
The diagnosis of leptospirosis is based on clinical suspicion (because of risk of exposure), and is very high when there is a local outbreak of the disease. When a patient presents with the initial flu-like symptoms, either no testing or non-specific testing (such as a complete blood count, urine test, etc.) may be done. More specialized blood tests (such as a microscopic agglutination test, blood cultures, enzyme-linked immunosorbent assay/ELISA, others) exist for this condition, but are limited in their accuracy and availability (they may need to be sent to specialized testing centers).
Leptospirosis is treated with appropriate (for the condition) antibiotics, although as noted above most cases resolve on their own and hence do not require treatment (some research shows antibiotics for the milder form of leptospirosis may shorten the duration of symptoms). The severe form of leptospirosis (Weil’s disease) requires aggressive supportive care (for example dialysis for kidney compromise, breathing support for severe pneumonia, etc.) as well as intravenous antibiotic therapy and other supportive treatments.
Leptospirosis is very uncommon in the U.S. (about 100 to 200 cases per year), with most cases being in people who have traveled to places where it is more common. However, this is a concerning condition worldwide, and because of that a vaccine to prevent this disease (not available in the U.S.) has been developed.
If leptospirosis is considered a reasonably likely diagnosis, antibiotics are usually begun (even though it is typically a self-limiting condition the possibility of shortening the duration of the illness is a reason many infectious disease specialists often recommend treatment). If you have traveled outside the country and then become ill, be sure to let your healthcare provider know about your travels, as there are many conditions that may be considered because of possible exposures during those travels even if you did not become ill until you returned home.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com