Climate Change and the Spread of Tropical Disease in Northern California

Reinette Senum
6 min readApr 15, 2017


Originally published at

Last week I was visiting my local veterinarian in Nevada City, CA because of my sick kitty, a Hurricane Katrina survivor named Katrina. While there I met a local resident, Allison Rivers Samson, who walked into the lobby with her cheery Dog, Zoe, shortly after I had arrived.

Zoe, a rescued pitbull/boxer mix, was the picture of health and had a smile on her face as she was most interested in my cat, Katrina. Katrina, however, didn’t demonstrate the same enthusiasm.

Allison and I began talking while we watched our pets react to one another. I had seen Allison around town, but didn’t know her by name so it was lovely to get to know her. I inquired about Zoe and that’s when Allison told me she was on death’s door only a short time before.

“Really?” I responded, “She looks so healthy and fairly young.”

That is when Allison began to inform me how Zoe had contracted a bacterium called Leptospirosis, or Lepto for short. While Lepto is thousands of years old until recently it was only found in the tropics, but because of climate change and all the unprecedented rain we have been receiving this deadly illness has expanded into Northern California.

I asked Allison if she could send me as much information as possible on this. She shared with me in an email that, “Lepto is passed through urine, so when dogs go sniffing urine on walks and/or drink stagnant water from those puddles pups love to lap they can be exposed if a wild rodent, deer, or horse who is contaminated with Lepto has urinated in the water.”


Leptospirosis is a very contagious and potentially fatal bacterial disease. There are a variety of animals including livestock such as buffaloes, horses, sheep, goat, and pigs, and wildlife such as raccoons, deer, skunks, and rodents that are common carriers of leptospires.

Rats in particular can harbor Lepto. Included on this list are dogs and cats, however, cats are more likely carriers and unlikely to fall ill due to a natural immune resistance.

It’s nearly impossible to avoid Leptospirosis: There are 200 different strains of Leptospirosis and depending on the strain it can affect the liver, kidneys, lungs, spleen, eyes, and genital tract.

Originally, Allison’s dog, Zoe, was having heart issues and showed no known signs of Lepto except for her lethargy. Zoe’s saving grace, however, was that she was taken to a vet in Roseville that had recently experienced 8 emergency cases of Lepto in the area motivating the Vet to regularly test for it. The vets were surprised by the positive test result from Zoe and as soon as they discovered this they immediately put Zoe onto antibiotics.


Allison continued in her email to me, “Lepto is zoonotic which means that humans can get it, so all three of us got tested. False negatives can occur so they recommend a second test in two weeks since our first test came back negative. Treatment is usually with tetracycline. We choose to limit our use of those so we are preventatively treating with natural antibiotics for the time being.

Zoe looking healthy!

Zoe is already on antibiotics, which immediately stops the shedding of the bacteria through urine, so we are no longer being exposed to it. The reason we got tested is that we don’t know how long she had it before the test.”

The majority of human infection is caused from contaminated water and generally this is through occupational cases where rice farmers, cane growers, sewage workers, and pest control workers are exposed to rodents. Included in this high-risk group are farmers, pet shop workers, veterinarians, sewer workers, slaughterhouse workers, meat handlers, and the military.

In the developed world one in five wild rats are Lepto carriers. The good news is that as soon as rat urine that contains the Lepto bacterium dries up it becomes inactive. Lepto bacterium is highly sensitive; it needs a moist environment in order to survive.

Swimmers and anglers are also at a greater risk particularly in stagnant or pooled waters. Lepto is not found in saltwater or moving water.

It may also mimic many other diseases, e.g. dengue fever, typhoid, viral hepatitis and other viral hemorrhagic diseases.

One of the largest human risks occurs when cats or dogs bring in dead rodents that have become infected. This is hard to avoid. A carrier, particularly in rodents and cats, can host Lepto and show no signs for an entire lifetime.

Infection can only happen if one comes in contact with body fluids. Skin to skin transfer and airborne is almost impossible. Leptospires can gain entry into humans through cuts and abrasions in the skin, through intact mucous membranes (nose, mouth, eyes) and perhaps through waterlogged skin. They may occasionally enter the human body via the inhalation of droplets of urine or via drinking-water.

During an animal’s treatment of Lepto great care must be taken to disinfect and clean any body fluids. Infected animals should also be kept separate from all other ranch or domesticated animals.


Symptoms to watch for in dogs:

  • Fever
  • Shivering
  • Muscle tenderness
  • Lethargy
  • Increased thirst
  • Changes in the frequency or amount of urination
  • Dehydration
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Jaundice
  • Inflammation of the eyes

In humans it shows up as flu-like symptoms.

“The clinical manifestations are highly variable. In general, the disease present in four broad clinical categories:

  • A mild, influenza-like illness
  • Weil’s syndrome characterized by jaundice, renal failure, hemorrhage and myocarditis with arrhythmias
  • Meningitis/meningoencephalitis
  • Pulmonary hemorrhage with respiratory failure

(Source: World Health Organization)


“The diagnosis of leptospirosis should be considered in any patient presenting with an abrupt onset of fever, chills, conjunctival suffusion, headache, myalgia and jaundice. The diagnosis is more difficult when patients present with symptoms of cough, dyspnea, nausea, vomiting, abdominal pain, diarrhea, arthralgias and a skin rash.

Conjunctival suffusion and muscle tenderness, most notable in the calf and lumbar areas, are the most distinguishing physical findings.

Suspicion is further increased if there is a history of occupational or recreational exposure to infected animals or to an environment potentially contaminated with animal urine. Once the possibility of leptospirosis has been considered, appropriate diagnostic tests and clinical management should be instituted.” (Source; World Health Organization)

While there is a vaccination for Lepto it only covers 4 of the 200 strains and it has its own serious side effects as well as possible risk of death.

Leptospirosis bacteria

What is most disturbing about what Allison had to say was how most local veterinarians and medical industry have not yet caught up to the spread of Lepto in our region.

I’m writing this not to scare anyone, but to alert pet owners and residents as well as the local medical and veterinary industry to this rising health risk. The best defense is knowledge. If you or any family members show any signs of Lepto seek medical assistance as soon as possible and inform your medical practitioner about Lepto just in case they have yet to learn about it. The same holds true if you see any signs with your own pets or ranch animals.

Again, education and public outreach are our best defense. So spread the word.

For further information on preventing infection, hygiene and cleaning, and frequently asked questions go to

and here for further canine information:



Reinette Senum

Blogger, storyteller, human-foghorn; I’m a community curator & activist determined to find and share the truth