Summertime Blues - No Dogs Allowed
Well, my kids finished school this week, and in my house, that is the official start of summer. For many of you, summer means beaches, lakes, and walking barefoot to feel sand and dirt squishing between your toes. Now, I love nothing better than walking down the beach, too, but the longer I practice medicine, the more my perspective on diseases changes. So, I want to give you a word of caution about those waterfront walks.
Have you seen those signs posted, “No Dogs Allowed”? At first, they will make you angry. However, the reason is worms! Common intestinal parasites. Hookworms and roundworms. Crazy, huh?! Let me explain.
Hookworms are common in puppies and kittens. They are voracious blood suckers, and they can cause such severe anemia in puppies and kittens that the infection is fatal. Puppies can be infected with hookworms before birth (kittens cannot), and both puppies and kittens can be infected from contaminated soil or by eating infected prey. Once the worms mature, they begin shedding eggs, which contaminate the environment. The eggs hatch, and the baby worms (larvae) begin maturing. As you run barefoot along the beach or in the park, those infective larvae penetrate your skin, and they begin burrowing through it – YUCK! This is called cutaneous larva migrans. This causes intense itching. Rarely, the worms will reach the GI tract of people, and if so, they will voraciously suck your blood and cause anemia. If you want to be totally grossed out, the CDC estimates that between 576 and 740 million people worldwide are infected with hookworms! The good news is that once diagnosed, hookworm infection is treatable!
Roundworms are also common in puppies and kittens. In fact, this is probably the most common parasite seen. Unlike hookworms, roundworms are less likely to cause anemia, but they can cause significant GI upset. They are also the reason for the “pot-bellied” appearance in young animals with high worm burdens because the worms are so large. Puppies can be infected in their dam’s uterus before they are born. They can be infected while nursing. They can also be infected from contaminated soil or from eating infected prey. One huge difference between hookworms and roundworms is that roundworm eggs take about 30 days in the environment before becoming infectious to people or animals.
Now, the biggest problem with roundworms is the public health risk. Most infections occur in people under 20 years of age, and children are at greatest risk of exposure. Most infections are mild. However, roundworm larvae can migrate through the liver, lungs, and central nervous system of people, causing fever, coughing, liver enlargement, or pneumonia. This condition is known as visceral larva migrans. The larvae can also migrate to the eye, and when they die, they cause tremendous inflammation. Vision loss occurs over days to weeks, and permanent blindness can results. This condition is known as ocular larva migrans. In the US, there are approximately 1,000 cases of ocular larva migrans annually, and about 700 result in permanent blindness in the affected eye!
The take home message is prevention. Wash your hands before cooking and eating. Be careful where you walk barefoot, or wear sandals/flip flops. Clean up your dogs’ feces. Cover your sandbox so that it isn’t used as a litterbox for the neighborhood cats, and stay away from places where dog feces are not cleaned regularly. Check fecals regularly, especially if your pet likes to hunt, and deworm them. Monthly heartworm preventives can be helpful. Ivermectin at heartworm preventive doses will not kill hookworms and roundworms, but ivermectin products that contain pyrantel pamoate will (check your label). Milbemycin and moxidectin will kill hookworms and roundworms at monthly heartworm doses.
Hopefully, you won’t be filled with summertime blues where no pets are allowed. For your safety, please protect yourself from hookworm and roundworm exposure, and have a fantastic summer!
