In this latter case, the virion is transported to the plasma membrane via microtubules. Some orthopoxviruses, including the monkeypox, cowpox, and buffalopox viruses, have the ability to infect non-reservoir species. Others, such as ectromelia and camelpox viruses, are highly host-specific. Vaccinia virus, maintained in vaccine institutes and research laboratories, has a very wide host range. Vaccine-derived vaccinia has been found replicating in the wild in Brazil, where it has caused infections in rodents, cattle, and even humans. Following the eradication of variola virus, camelpox has become one of the most economically important "Orthopoxvirus" infections due to the dependence of many subsistence-level nomadic communities on camels. Following the eradication of the human-specific variola virus (smallpox), all human "Orthopoxvirus" infections are zoonoses. Monkeypox occurs naturally only in Africa, particularly in the Democratic Republic of the Congo. However, human and prairie dog cases have occurred in the US due to contact with animals imported from Ghana. Cowpox only occurs in Europe and adjacent Russian states, and despite its name, occurs only rarely in cattle. One common host is the domestic cat, from which human infections are most often acquired. Cowpox virus has also infected a variety of animals in European zoos, such as elephants, resulting in human infection. Aerosols of concentrated virus may result in" Orthopoxvirus" infection, especially in unimmunized individuals. In addition, needle sticks with concentrated virus or scratches from infected animals may result in local infection of the skin even in immunized individuals. Cowpox infection in Europe is an occupational hazard for veterinary workers, and to a lesser extent, farm workers. The initial symptoms of" Orthopoxvirus "infection include fever, malaise, head and body aches, and occasionally vomiting. With the exception of monkeypox infection, one lesion is the norm, although satellite lesions may be produced by accidental autoinoculation. Individual lesions, surrounded by inflammatory tissue, develop and progress through macules, papules, vesicles, and pustules, and eventually become dry crusts. (Lesions alone are not diagnostic for "Orthopoxvirus "infection and may be mistaken for zoonotic "Parapoxvirus" infections, anthrax or "Herpesvirus" infections.)