feed on the host's blood, and can cause hyperchromic anemia, emaciation, diarrhea, and possibly death. Toxocara canis, a hookworm known to infect wolf pups in the uterus, can cause intestinal irritation, bloating, vomiting, and diarrhea. Wolves may catch Dioctophyma renale from minks, which infects the kidneys, and can grow to lengths of . D. renale causes the complete destruction of the kidney's functional tissue and can be fatal if both kidneys are infected. Wolves can tolerate low levels of Dirofilaria immitis for many years without showing any ill effects, though high levels can kill wolves through cardiac enlargement and congestive hepatopathy. Wolves probably become infected with Trichinella spiralis by eating infected ungulates. Although T. spiralis is not known to produce clinical signs in wolves, it can cause emaciation, salivation, and crippling muscle pains in dogs. Thorny-headed worms rarely infect wolves, though three species have been identified in Russian wolves: Nicolla skrjabini, Macracanthorhynchus catulinus, and Moniliformis moniliformis. Status and conservation The global wild wolf population in 2003 was estimated at 300,000. Wolf population declines have been arrested since the 1970s. This has fostered recolonization and reintroduction in parts of its former range as a result of legal protection, changes in land use, and rural human population shifts to cities. Competition with humans for livestock and game species, concerns over the danger posed by wolves to people, and habitat fragmentation pose a continued threat to the wolf. Despite these threats, the IUCN classifies the wolf as Least Concern on its Red List due to its relatively widespread range and stable population. The species is listed under AppendixII of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning international trade in the species (including parts and derivatives) is regulated. However, populations of Bhutan, India, Nepal and Pakistan are listed in AppendixI which prohibits commercial international trade in wild-sourced specimens. North America In Canada, 50,000–60,000 wolves live in 80% of their historical range, making Canada an important stronghold for the species. Under Canadian law, First Nations people can hunt wolves without restrictions, but others must acquire licenses for the hunting and trapping seasons. As many as 4,000 wolves may be harvested in Canada each year. The wolf is a protected species in national parks under the Canada National Parks Act. In Alaska, 7,000–11,000 wolves are found on 85% of the state's area. Wolves may be hunted or trapped