Miami Beach's Cat Poop Map
Miami Beach officials, disturbed by reports of a hookworm outbreak, have taken a rather unique approach to the problem: they've created a cat and cat poop map.
This fall, several cases of cutaneous larval migrans were reported - and highly publicized - in the Miami Beach area, something that is of particular concern for a tourist city that doesn't want people thinking the city's beaches are biohazardous.
Cutaneous larval migrans is a skin condition caused by migration of hookworm larvae through the skin. Dogs and cats can be carries of hookworms and pass eggs in their feces. Larvae then hatch from these eggs and can penetrate the skin (of people and animals alike) after being in the environment for a few (usually 2-9) days. If someone has contact with infectious larvae, such as by stepping on them while bare foot on a beach, the larvae get into their skin and start migrating, causing this very itchy skin condition.
Feral (stray) cats are the main problem in Miami Beach. Stray cats and beaches are a bad combination, since stray cats tend to have high rates of hookworm carriage, they often defecate in sand on the beach, and of course people often have direct contact between bare skin and beach sand. Identifying where stray cats live (and poop) is important for disease control and public education. "We needed to identify where the cats are eating — and where they're pooping — to address this problem" stated a program organizer. To do this, city sanitation workers were given GPS devices and instructions to go find cats. Data were uploaded into a mapping system, and areas where cats tend to congregate were identified. Not surprisingly, certain areas of sane dunes are being used as industrial-sized litterboxes by the cats.
This type of information can be used in several ways. It can be useful for evaluating cat populations: where they are, where they go, and what happens to them over time. It can help identify areas where the cat population needs to be addressed through measures such as trap, neuter and release programs (as are being used in Miami Beach). It can also help with development of targeted education programs, by putting up warnings in heavily cat- and cat poop-infested areas. City health officials think that the combination of tracking, the increased spay/neuter program and targeted warnings to sunbathers have helped staunch the outbreak.
Image source: http://blogs.miaminewtimes.com
Seagulls, beaches and bad bugs
Just as I'm getting ready to go on vacation (that will hopefully involve some time on the beach), I read an article in the latest edition of Emerging Infectious Diseases about seagulls and beaches as reservoirs of multidrug-resistant E. coli (Simoes et al 2010). In this study, the researchers collected seagull poop from beaches in Porto, Portugal and tested them for the presence of extended spectrum beta-lactamase (ESBL) E. coli, a highly drug resistant form of this common bacterium. Thirty-two percent (32%) of the E. coli they isolated were ESBL, a pretty impressive rate in wild birds that would not be directly exposed to antibiotics. Various E. coli strains were present, including some that can cause severe disease.
In some respects this is pretty concerning, and in other respects not too surprising. We know that birds in various (including remote) regions can carry multidrug-resistant bacteria. The ability of wild birds to carry these bacteria, combined with the wide geographic range that some bird species have, raises concern about the role of birds in the spread of antibiotic-resistant bacteria, as well as the potential for contracting a nasty drug-resistant infection while on the beach. Birds certainly have the ability to help spread certain types of bacteria over wide ranges. However, their overall role is probably very limited compared to the role played by people and (domestic) animals. For birds to become carriers of these bacteria, they have to pick them up from somewhere, which presumably doesn't occur until the bacteria have built up to a good level in people and/or animals. I doubt that birds account for many human infections. Antibiotic exposure through antibiotic residues in water or food sources could also play a role in the presence of these bacteria in birds, but that's an area that's not well understood.
So, how does this influence my time on the beach? Not much. I wasn't really planning on having contact with seagull poop, and this paper just reinforces that basic precaution. Other basic measures such as keeping open sores covered, avoiding cuts by wearing shoes in rough areas or sand that might be contaminated with sharp objects, avoiding contamination of food with sand, avoiding areas with obvious bird poop contamination, and hand washing before eating and after leaving the beach are easy to do.
Banning Bowser from the beach
Many dog owners love to take their canine companions to the beach with them during the summer. Unfortunately, other people (particularly non-dog owners) sometimes take exception to having Bowser on the beach. These individuals often cite potential infectious disease risks as a reason to ban dogs from the beach.
While there are some potential infectious disease risks associated with having pet dogs at the beach, they are minimal. Also, some simple, common-sense steps can greatly reduce the risks that do exist. The infectious disease risks from feral (wild) dogs and wildlife defecating in the sand are much greater.
- The biggest health risk is actually probably from dog bites. Bites can be avoided through proper handling and training of dogs that are brought to public beaches.
- Many different bacteria (e.g. Salmonella, Campylobacter) can be passed in the stool of even healthy dogs. Some of these can be harmful to people, but only under certain circumstances, such as if they are swallowed or if they contaminate an open wound.
- Promptly picking up any stool passed by a dog greatly reduces the risk of significant contamination of the sand. Also, sunlight is an excellent “disinfectant” and will help kill any residual bacteria left behind.
- Dogs can also have different kinds of zoonotic parasites in their stool.
- Some of these parasites (e.g. roundworms, hookworms) are passed in a form that takes days to become infectious to people. So promptly removing dog stool from the beach minimizes the risk of transmission.
- Other parasites, such as Giardia, are immediately infectious when passed in the stool, but must be swallowed to cause infection. Prompt removal of dog stool, good hand hygiene with soap and water or an alcohol-based hand sanitizer before eating, and avoiding sand contamination of food and drink should largely eliminate this risk as well.
Overall, the risks of having dogs on beaches are very low if people behave responsibly, specifically properly restraining their dogs and promptly picking up stool.
More information about zoonotic diseases associated with contamination of sand and Sandboxes is available on the Worms & Germs Resources page.
