By Joy Pape, FNP-C and Nicole Cerniello, DVM


Since it’s even hotter than most summers, Dr. Nicole Cerniello recommended we write about leptospirosis this month. Although I have been in the medical field for years, I have not personally known a patient who had leptospirosis. So, I communicated directly with the New York State Department of Health (NYS DOH) and The New York City Department of Health and Mental Hygiene (NYC DOHMH) to find out what we New Yorkers need to know.

Leptospirosis, also called “lepto,” is a zoonotic bacterial infectious disease. Zoonotic diseases are passed from non-humans to humans and even vice-versa. Lepto is mainly spread from non-humans to humans. It is not very common in humans.


NYC DOH reports that leptospirosis is a disease largely caused by bacteria in the urine of infected animals. In NYC, rats are the most common cause. Infections can also happen through contaminated water, soil or food. Bacteria can enter the body through the eyes, nose, mouth or an open wound. Leptospirosis is not usually spread from person to person and there is no vaccine.

Dr. Kara Mitchell, Ph.D., Research Scientist of Emerging Infectious Diseases, told me, “Although the numbers are low, there are many reasons for the increase in New York, such as climate change, rain, flooding and, commonly, the rats.”

NYC DOHMH reports that lepto is rarely found in NYC but the number of people diagnosed in the city has increased in recent years.


You can become sick between two days and four weeks after exposure. Some infected people may have no symptoms. Others may have a mild illness with:
• Fever
• Headache
• Chills
• Muscle aches
• Vomiting
• Diarrhea
• Red eyes
• Jaundice (yellow skin and eyes)

On rare occasions, severe illness can develop. Dr. Mitchell said, “It can occur in two phases. After getting over the milder symptoms, if a second phase occurs, the person can become ill again and develop kidney or liver failure.” Infectious disease specialists will look for causes of exposure such as the environment, work situation, etc.


Rats and small mammals are to blame for the spread of lepto throughout the city and, unfortunately, the West Village is no stranger to rats. Lepto is an incredibly hardy bacteria and can last in the environment for up to three weeks!

The best way to prevent leptospirosis is to avoid contact with rats by following these tips:
• Avoid places where rats may have urinated.
• If you are cleaning areas where rats have been, use a solution of one part bleach and ten parts water.
• Protect yourself from contact by wearing rubber gloves, especially if you have cuts or sores on your hands or arms.
• Wash your hands with soap and warm water after any contact with areas where rats may live.
• Always wear shoes when taking trash out.
• When traveling to tropical regions, do not swim or wade in water that might contain animal urine.


See a health care provider if you think you have leptospirosis. You may need to take blood tests or start antibiotics.


It is unlikely that your dog will contract lepto but, because of its zoonotic nature, it is incredibly important to talk about. Only a handful of cases are reported in NYC annually, mostly in Manhattan, but it may be underreported in dogs with mild infections.

Dogs typically show clinical signs one to two weeks after exposure that can range from vague symptoms such as lethargy, fever and lack of appetite to more severe symptoms of kidney and liver failure.

Despite the unlikelihood of your dog catching lepto, Dr. Cerniello encourages dog owners to vaccinate against lepto. While not considered a “core vaccine,” she treats it as such. She also discusses it with all puppy owners, as well as new patients without a lepto vaccine. The vaccine gives dogs immunity to the four most common subtypes. After an initial two booster protocols, this vaccine is given annually.

Lepto in cats is extremely rare as they seem to be much more immune than dogs. Even when cats are infected, they seem to show little to no symptoms.

Joy Pape, FNP-C, CDCES, CFCN is a board-certified family nurse practitioner who believes in and practices holistic health and healing. Dr. Nicole Cerniello, DVM is Medical Director for the Greenwich Village Animal Hospital.