Snakes, like all animals, host a diverse range of parasitic organisms both externally and internally. While parasite loads are often manageable in wild snakes, the confined conditions of captivity can allow these parasites to multiply rapidly, turning a mild infection into a serious health crisis. Understanding these organisms is important for anyone involved with snake care, whether in conservation or keeping a pet.
External Parasites: Mites and Ticks
The most frequently encountered external parasite is the snake mite, Ophionyssus natricis, a tiny, blood-feeding arachnid often described as looking like a speck of moving black or reddish-black pepper. Mites congregate in areas where scales meet, such as around the eyes, in the heat pits, or near the vent. They pierce the snake’s skin to feed, and a single engorged female can lay up to 80 eggs.
The mite life cycle is short, sometimes completing in as little as 13 to 19 days, allowing infestations to quickly overwhelm a host. Eggs are sticky and often laid in dark, humid crevices of the enclosure. After hatching, the larval stage does not feed, but the subsequent nymph stages are highly mobile and must feed on blood to develop. A snake with mites may exhibit unusual behavior, such as spending excessive time soaking in its water bowl in an attempt to drown the parasites.
Ticks are another common ectoparasite, particularly on wild-caught or outdoor-kept snakes. Unlike mites, ticks embed their mouthparts deeply into the snake’s skin, requiring delicate removal to prevent leaving the head embedded. Heavy infestations can lead to significant blood loss, resulting in anemia. Furthermore, these external parasites may also act as mechanical vectors, potentially transmitting other disease-causing agents.
Internal Parasites: Worms and Protozoa
Snakes are susceptible to a wide variety of internal parasites (endoparasites), which fall primarily into two groups: multicellular worms (helminths) and single-celled organisms (protozoa). Helminths include nematodes (roundworms), frequently found in the gastrointestinal tract, lungs, or under the skin. Species like Kalicephalus (hookworms) or Ophidascaris can cause inflammation and ulceration in the digestive system.
Lungworms, such as Rhabdias species, inhabit the respiratory system and can cause breathing difficulties, while other nematodes have larvae capable of penetrating the snake’s skin directly. Internal parasites are often acquired when a snake ingests an infected prey animal (an intermediate host) or by consuming eggs or larvae from a contaminated environment. Cestodes (tapeworms) and trematodes (flukes) are also sometimes seen, though less commonly in captive-bred snakes because their life cycles usually require an intermediate host.
Protozoa are microscopic, single-celled parasites that can be highly pathogenic, with Cryptosporidium and Entamoeba invadens being particularly significant. Cryptosporidium serpentis primarily infects the stomach, causing the lining to thicken and impairing digestion. This infection is highly contagious, and the oocysts, the infective form of the parasite, are extremely hardy, surviving for long periods in the environment. Entamoeba invadens causes amoebiasis, leading to severe gastrointestinal distress and often rapid death in susceptible snake species.
Recognizing the Impact on Snake Health
A parasitic burden places a significant strain on a snake’s body, often manifesting in recognizable clinical signs. One common symptom of gut-dwelling parasites is regurgitation, where the snake brings up partially digested food due to irritation or obstruction. This inability to properly digest and absorb nutrients leads to progressive weight loss and a general state of emaciation.
External parasites cause anemia through continuous blood loss, contributing to lethargy and general weakness. Infestations also interfere with proper skin shedding, resulting in dysecdysis (retained patches of old skin). Wounds created by external parasites and damage caused by internal worms serve as entry points for bacteria, leading to secondary infections. This overall health decline is often driven by the parasites weakening the snake’s immune system, making it vulnerable to other diseases.
Zoonotic Risk and Prevention
A frequent concern for snake owners involves the possibility of parasites transferring from their reptile to themselves or other household pets, a phenomenon known as zoonotic risk. Most snake parasites are species-specific, meaning they pose a low risk to humans or mammals. For instance, the Cryptosporidium species that infects snakes is generally not the same one that infects humans.
Some snake parasites do carry zoonotic potential, most notably pentastomids (tongue worms), which are primitive arthropods inhabiting various snake tissues. Human infection, or pentastomiasis, usually occurs through the ingestion of undercooked snake meat, though transmission via contact with nasal secretions or feces has been described. Similarly, some helminths, especially larval roundworms, can be transmitted if humans accidentally ingest parasite eggs from a contaminated environment.
Preventing parasitic infection relies heavily on consistent hygiene and observation. Strict quarantine of any new snake for several months is a cornerstone of prevention. Regular veterinary check-ups and fecal screenings are necessary to detect internal parasites before they cause severe disease. Fastidious cleaning practices, including the immediate removal of feces and the use of appropriate disinfectants, minimize environmental contamination and break the parasites’ life cycles.