Animal and Veterinary Service (AVS) said it was notified of four confirmed cases of leptospirosis in pet dogs in the past two weeks from the Upper Thomson and Shunfu area (as reported in The Straits Times on 28 Jan 2024).
This marked increase in the number of cases is likely due to the rainy season.
AVS has sent out a circular to all veterinary clinics in Singapore regarding this notifiable zoonotic disease.
WHAT IS LEPTOSPIROSIS?
Leptospirosis is a zoonosis that occurs worldwide and is endemic in Singapore.
The pathogenic spirochaetes of the genus Leptospira is the perpetrator.
Pathogenic leptospires live in the kidneys of a large variety of mammalian species, including rats, and are excreted into the environment in the urine.
Leptospirosis is spread through the urine of these infected animals, which can get into water or soil and can survive there for weeks to months.
Pathogenic leptospires survive longer in warm and humid soil and stagnant water in environments.
Therefore, the disease is particularly prevalent in wet tropical and subtropical regions, like Singapore.
The bacterium can be destroyed in dry conditions, extreme temperature changes, and detergents.
More than 10 different serovars have been associated with disease in dogs worldwide, although the exact serovars responsible in specific geographic locations remain poorly understood due to the difficulties associated with the culture of leptospires.
HOW DOES IT SPREAD?
A study funded by the Ministry of Environment and Water Resources (Singapore), and the Future Systems and Technology Directorate, Ministry of Defence was conducted over a period of 2 years 2 months (published in Feb 2022), on 1143 live rodents obtained via opportunistic sampling conducted by pest control professionals registered with the Singapore Pest Management Association and from the trapping done by this particular research team throughout Singapore showed 42.4% were positive of Leptospira spp.
Humans and animals can become infected through contact with contaminated urine or other body fluids, (except saliva), water, or soil.
The bacteria enters the body through skin or mucous membranes (eyes, nose, or mouth), especially if the skin is broken from a cut or scratch.
Drinking contaminated water can also cause infection.
Your pets have a higher risk of becoming infected if they are allowed to explore contaminated areas, stagnant water, and soil.
Infected pets can pass the disease to each other and to their human owners when infected, but this happens very rarely.
The time between exposure to the bacteria and the development of symptoms is usually 5 to 14 days but can be as short as a few days or as long as 30 days or more.
HOW DO YOU KNOW?
Leptospira attaches to cells that line blood vessels and make it harder for blood to clot normally - resulting in spontaneous bleeding under the skin (petechiae and/or ecchymosis).
The bacteria can spread throughout the body and affect organs, often causing liver, kidneys, lungs, genital tract, and central nervous system issues.
Common signs seen:
Fever
Decreased appetite
Vomiting
Diarrhea
Increased thirst and urination
Lethargy or weakness
Stiffness and soreness
Dehydration
Jaundice
Breathing issues
Redness in the eyes
Death
Your veterinarian will recommend blood tests, such as baseline haematology and biochemistry, a PCR test to look for DNA of the Leptospira organism, testing for antibodies and urine tests.
HOW TO PREVENT?
NO RAT FRIENDS
Stay away from rodent-infested (rats, mice, or other animal pests) areas, e.g. rubbish chute areas, and areas behind food establishments.
Keep your environment clean and dispose of your garbage responsibly so there is no rodent infestation in your area.
NO WILDLIFE FRIENDS
Avoid contact with wildlife.
VACCINE
Vaccinate your dogs annually with the leptospirosis vaccine(s).
The vaccine does not provide 100% protection because there are many strains (types) of leptospires and the vaccine does not provide immunity against all strains.
It is important to get your pet vaccinated again even if it has had leptospirosis because it can still get infected with a different strain of leptospires.
If this is the first vaccine, your dog will need a booster after 3-4 weeks.
Your dog should then receive a booster once a year.
KEEP DRY
Avoid access to standing / stagnant puddles of water.
KEEP CLEAN
Wash your pets after outings.
Wash your hands diligently.
Lifestyle changes to prevent a potentially deadly disease are much simpler than wrestling with high medical fees and the risk of death.
Attribution:
Griffiths, J., Yeo, H.L., Yap, G. et al. Survey of rodent-borne pathogens in Singapore reveals the circulation of Leptospira spp., Seoul hantavirus, and Rickettsia typhi. Sci Rep 12, 2692 (2022). https://doi.org/10.1038/s41598-021-03954-w
Sykes, Jane E. Vaccination Overview: Leptospirosis, TVP, Vol 11 Number 4, Jul/Aug 2021. https://todaysveterinarypractice.com/preventive-medicine/vaccination-overview-leptospirosis/
Dr. Cohen, Aly. Canine Leptospirosis. https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/health-info/canine-leptospirosis#:~:text=There%20are%20multiple%20strains%20of,avoiding%20common%20sources%20of%20contamination.
https://www.cdc.gov/leptospirosis/index.html
https://www.msdvetmanual.com/generalized-conditions/leptospirosis/leptospirosis-in-animals-overview
LEPTOSPIROSIS + CATS
Almost every mammalian species can become a carrier for Leptospira after exposure, yet in the past, experts believed that cats were not susceptible to infection.
Although the literature on the clinical presentation of leptospirosis in cats is scarce, it has been demonstrated that cats are susceptible to infection and that Leptospira might play a role in the development of long-term kidney diseases in cats.
Healthy-looking cats, with leptospirosis, are likely underestimated owing to the lack of overt clinical signs commonly associated with this disease.
Studies showed the prevalence of anti-leptospiral antibodies in cats varies from 4% to 33.3% depending on the geographical location.
Urinary shedding of leptospires in naturally infected cats has also been reported, with a prevalence of up to 68%.
REALLY?
A study conducted in Malaysia (Johor and Selangor) to determine the presence of anti-Leptospira antibodies in healthy, adult cats from 4 different shelters between June 2017 and February 2018 showed that 20 of the 110 sheltered cats sampled were positive for Leptospira (various serovars).
Another similar study done in Thailand in 2019 detected anti-Leptospira antibodies in 14 of the 260 cats tested.
Although there are no studies available on the prevalence of leptospira infection in cats in Singapore, we have to assume that a higher risk exists within our community cats and roaming cats due to the association with the exposure/ hunting and/ or consumption of infected prey, especially rodents.
PROTECT THE CATS TOO
NO VACCINE
There is no commercial leptospirosis vaccine available for cats.
REDUCE EXPOSURE
Preventing exposure/ avoidance of contact with stagnant water, contaminated areas/ soil, and urine from infected animals is the best policy.
RODENT CONTROL
Keep your environment clean and dispose of your garbage responsibly so there is no rodent infestation in your area.
PPE
If you are a cat feeder, personal protective equipment (e.g. gloves) should be used when handling or associating with potentially infected community cats to prevent zoonosis.
Attribution:
Alashraf AR, Lau SF, Khairani-Bejo S, et al. First report of pathogenic Leptospira spp. isolated from urine and kidneys of naturally infected cats. PLoS One. 2020;15(3):e0230048. Published 2020 Mar 10. doi:10.1371/journal.pone.0230048
Sprißler F, Jongwattanapisan P, Luengyosluechakul S, Pusoonthornthum R, Prapasarakul N, Kurilung A, Goris M, Ahmed A, Reese S, Bergmann M, Dorsch R, Klaasen HLBM, Hartmann K. Leptospira infection and shedding in cats in Thailand. Transbound Emerg Dis. 2019 Mar;66(2):948-956. doi: 10.1111/tbed.13110. Epub 2019 Jan 7. PMID: 30580489.
Abdul Rahman Alashraf, Seng Fong Lau, Kuan Hua Khor, Siti Khairani-Bejo, Abdul Rani Bahaman, Mohd Azri Roslan, Mohd Sabri Abdul Rahman, Soon Heng Goh, Rozanaliza Radzi, Serological Detection of Anti-Leptospira Antibodies in Shelter Cats in Malaysia, Topics in Companion Animal Medicine, Volume 34, 2019, Pages 10-13, ISSN 1938-9736, https://doi.org/10.1053/j.tcam.2018.12.002.
Murillo A, Goris M, Ahmed A, Cuenca R, Pastor J. Leptospirosis in cats: Current literature review to guide diagnosis and management. Journal of Feline Medicine and Surgery. 2020;22(3):216-228. doi:10.1177/1098612X20903601