Camelpox is a disease of camels caused by the camelpox virus (CMPV) of the family Poxviridae, subfamily Chordopoxvirinae, and the genus Orthopoxvirus. It causes skin lesions and a generalized infection. Approximately 25% of young camels that become infected will die from the disease, while infection in older camels is generally more mild.[1] Although rare, the infection may spread to the hands of those that work closely with camels.[2]
The camelpox virus that causes camelpox is an orthopoxvirus that is very closely related to the variola virus that causes smallpox. It is a large, brick-shaped, enveloped virus that ranges in size from 265–295nm. The viral genetic material is contained in a linear double-stranded DNA consisting of 202,182 tightly packed base pairs.[3] The DNA is encased in the viral core. Two lateral bodies are found outside the viral core, and are believed to hold the enzymes required for viral reproduction.[4]
The camelpox virus most often affects members of family Camelidae. However, recent studies show that the disease can be transmitted to both humans and arthropods.[5]
Transmission
Camelpox virus can be transmitted through milk to calves
The camelpox virus is spread in three ways: direct contact, indirect contact, and insect vectors.[citation needed]
In direct contact infection, a camel becomes infected after direct contact with an infected camel.[citation needed]
In indirect contact infection, a camel becomes infected after contact with an infected environment. The virus is spread through milk, saliva, ocular secretions, and nasal secretions, and has been shown to remain virulent outside of a host for four months.[6]
The camelpox virus has been isolated from camel ticks (Hyalomma dromedarii) removed from infected animals. It is believed that the ticks can transmit the disease from camel to camel. This theory is supported by increases in Camelpox infections immediately following heavy rains, during which the camel tick population increases greatly.[7]
Transmission of camelpox to humans was confirmed in 2009 when camel herders in India presented with infections of the hands and fingers. Although other cases of human infection have been reported, no other cases have been verified. Due to the close contact between camels and their human handlers in much of the world, it is believed that camelpox is transmitted to humans via direct contact.[8]
Replication
The orthopox virus that causes camelpox behaves very similarly to the virus that causes smallpox. After the virus attaches to a host cell, it injects its viral core (the shell containing its DNA) into the cell's cytoplasm. The virus carries DNA polymerase which is used to transcribe its genes. Eventually, the viral core dissolves, and the genetic material is bare within the cytoplasm. When all of the structural proteins have been produced, viral assembly takes place. The newly formed virus particles can be released during cell lysis, or they can derive a host cell produced membrane and be released via budding.[9]
Signs and symptoms
Skin lesions observed in infected camels. (A) Skin lesions on the neck and (B) hip of the left rear leg of an infected camel. Enlargement of (C) stiff papules and (D) ulcerated papules with purulent secretion.
Camels
The incubation period of camelpox is between 3 and 15 days. The resulting infection can be classified as acute or generalized. Generalized infections are usually found in camels over the age of three, and are characterized by swollen lymph nodes, fever, and the development of skin lesions. The lesions begin as papules, but develop into pustules. These external symptoms usually begin on the head and neck, but eventually spread throughout the body, being especially concentrated on the limbs and genitalia. Without treatment, the animal will generally recover from the infection in 4 to 6 weeks.[6]
Acute infections are usually found in camels under the age of three, and result in mild to severe systemic infections. In addition to the symptoms that accompany a generalized infection, these animals experience internal lesions along the lining of the mouth, and respiratory and digestive tracts. They also experience loss of appetite and diarrhea. A large proportion of camels acutely infected with camelpox die, although death is often attributed to a secondary infection.[10]
Humans
Camelpox infections in humans result in mild skin lesions on the hands and fingers. Reports have been made that the lesions can be found on the mouth and lips if the patient drank milk from an infected camel, but these symptoms have not been confirmed.[8]
Diagnosis and treatment
Camelpox diagnosis can be based on symptoms. However, both Camel Contagious Ecthyma and Camel Papillomatosis cause indistinguishable symptoms under similar conditions.[11] Therefore, the best way to diagnose Camelpox is via Transmission Electron Microscopy evaluation of skin samples from infected animals. The camelpox virus has a unique shape that is readily identifiable using this method. In cases where TEM technology is not available, serological tests are available to identify camelpox as the causative agent for infection.[6] Additionally, researchers in India are working on a diagnostic polymerase chain reaction to quickly and effectively identify the camelpox virus.[12]
When the camelpox virus is identified as the causative agent, the disease can be treated with anti-viral medications. The most common medication used to treat camelpox is Cidofovir, a broad spectrum anti-viral that acts by inhibiting the viral DNA polymerase. Cidofovir has proven to be 100% effective at preventing death in infected camels.[13]
Prevention
Camelpox outbreaks have a negative effect on the local economies. Outbreaks often lead to the loss of young camels, and render older camels useless in terms of milk and meat production, and transportation. As such, attempts are often made to prevent transmission of the disease. An attenuated vaccine is currently available that provides long term protection against camelpox if administered when the camel is at least 9 months old. An inactivated vaccine is also available, but must be administered yearly to maintain protection.[6]
The camelpox virus is sensitive to a number of common disinfectants. It can also be destroyed by autoclaving, short term exposure to UV light, and boiling for at least 10 minutes. These methods may be used by camel herders to minimize risk of environmental contamination.[6]
Society and culture
In 1995 Saddam Hussein admitted to having a number of top Iraqi scientists working to turn camelpox into a biological weapon. Camelpox was chosen for two main reasons: the theory that the local population would be largely immune, and its relation to smallpox. It is believed that the reported cases of camelpox infection in humans is low due to an immunity gained from exposure to camels during early childhood. Therefore, a significant proportion of Iraq's population would be immune to camelpox, while troops from non-camel herding countries would be susceptible.[14] It is not believed that the research process was successful, or that the virus was ever produced in any great quantities.[15]
Notes and references
↑ Fenner, Frank J.; Gibbs, E. Paul J.; Murphy, Frederick A.; Rott, Rudolph; Studdert, Michael J.; White, David O. (1993). Veterinary Virology (2nd ed.). Academic Press, Inc. ISBN978-0-12-253056-2.
↑ Carter, G.R.; Wise, D.J. (2006). "Poxviridae". A Concise Review of Veterinary Virology. Archived from the original on 26 June 2005. Retrieved 10 June 2006.
↑ Jezek, Z; Kriz, B (1983). "Camelpox and its risk to the human population". Journal of Hygiene, Epidemiology, Microbiology, and Immunology. 27 (1): 29–42. PMID6304186.
1 2 3 4 5 "Camelpox"(PDF). Terrestrial Animal Health Code. World Organization for Animal Health. Archived from the original(PDF) on 17 June 2012. Retrieved 31 March 2012.
↑ Wernery, U; Kaaden (1997). "Orthopox virus infections in dromedary camels in the United Arab Emirates (UAE) during winter season". Journal of Camel Practice and Research. 4 (1): 51–55.
↑ Khalafalla, A (1998). "Epizootiology of Camel Pox, Camel Contagious Ecthyma and Camel Papillomatosis in the Sudan". Animal Production Under Arid Conditions. 2: 115–131.
Cowpox is an infectious disease caused by the cowpox virus (CPXV). It presents with large blisters in the skin, a fever and swollen glands, historically typically following contact with an infected cow, though in the last several decades more often from infected cats. The hands and face are most frequently affected and the spots are generally very painful.
Mpox is an infectious viral disease that can occur in humans and other animals. Symptoms include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes. The illness is usually mild, and most of infected individuals recover within a few weeks without treatment. The time from exposure to the onset of symptoms ranges from three to seventeen days, and symptoms typically last from two to four weeks. However, cases may be severe, especially in children, pregnant women, or people with suppressed immune systems.
Orf is a farmyard pox, a type of zoonosis. It causes small pustules in the skin of primarily sheep and goats, but can also occur on the hands of humans. A pale halo forms around a red centre. It may persist for several weeks before crusting and then either resolves or leaves a hard lump. There is usually only one lesion, but there may be many, and they are not painful. Sometimes there are swollen lymph glands.
Parapoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Chordopoxvirinae. Like all members of the family Poxviridae, they are oval, relatively large, double-stranded DNA viruses. Parapoxviruses have a unique spiral coat that distinguishes them from other poxviruses. Parapoxviruses infect vertebrates, including a wide selection of mammals, and humans.
Orthopoxvirus is a genus of viruses in the family Poxviridae and subfamily Chordopoxvirinae. Vertebrates, including mammals and humans, and arthropods serve as natural hosts. There are 12 species in this genus. Diseases associated with this genus include smallpox, cowpox, horsepox, camelpox, and mpox. The most widely known member of the genus is Variola virus, which causes smallpox. It was eradicated globally by 1977, through the use of Vaccinia virus as a vaccine. The most recently described species is the Alaskapox virus, first isolated in 2015.
Buffalopox is caused by buffalopox virus (BPXV); it is a Poxviridae for which the natural host is buffalo. It mainly infects buffalo but has been known to infect cows and humans. It is classified in the Orthopoxvirus (OPV) genus and the subfamily Chordopoxvirinae. The appearance of buffalopox follows a pattern and is described as emerging and re-emerging, it commonly occurs in sporadic and epidemic forms in domestic and commercial farm settings.
Ectromelia virus (ECTV) is a virus of the family Poxviridae and the genus Orthopoxvirus that causes mousepox, a disease of mice. It has only been seen in mouse colonies kept for research purposes but believed that wild populations of mice and other rodents in Europe are naturally infected with ECTV. Mousepox causes skin lesions, a purulent rash on the body of mice, and generalized disease, which can be fatal. It is the only poxvirus to cause disease naturally in mice.
Molluscum contagiosum virus (MCV) is a species of DNA poxvirus that causes the human skin infection molluscum contagiosum. Molluscum contagiosum affects about 200,000 people a year, about 1% of all diagnosed skin diseases. Diagnosis is based on the size and shape of the skin lesions and can be confirmed with a biopsy, as the virus cannot be routinely cultured. Molluscum contagiosum virus is the only species in the genus Molluscipoxvirus. MCV is a member of the subfamily Chordopoxvirinae of family Poxviridae. Other commonly known viruses that reside in the subfamily Chordopoxvirinae are variola virus and monkeypox virus.
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Rabbitpox is a disease of rabbits caused by a virus of the genus Orthopoxvirus in the family Poxviridae, and closely related to vaccinia virus. Rabbitpox was first isolated at the Rockefeller Institute in New York in 1933, following a series of epidemics in the laboratory rabbits. It is an acute disease only known to infect laboratory rabbits as no cases have been reported in wild rabbits; it cannot infect humans.
Capripoxvirus is a genus of viruses in the subfamily Chordopoxvirinae and the family Poxviridae. Capripoxviruses are among the most serious of all animal poxviruses. All CaPV are notifiable diseases to the OIE. Sheep, goat, and cattle serve as natural hosts. These viruses cause negative economic consequences by damaging hides and wool and forcing the establishment of trade restrictions in response to an outbreak. The genus consists of three species: sheeppox virus (SPPV), goatpox virus (GTPV), and lumpy skin disease virus (LSDV). They share no serological relationship with camel pox, horse pox, or avian poxes. Capripoxviruses for sheeppox and goatpox infect only sheep and goat respectively. However, it is probable that North American relatives, the mountain goat and mountain sheep, may be susceptible to the strains but has not been experimentally proven. Lumpy skin disease virus affects primarily cattle, but studies have been shown that giraffes and impala are also susceptible to LSDV. Humans cannot be infected by Capripoxviruses.
The monkeypox virus is a species of double-stranded DNA virus that causes mpox disease in humans and other mammals. It is a zoonotic virus belonging to the Orthopoxvirus genus, making it closely related to the variola, cowpox, and vaccinia viruses. MPV is oval, with a lipoprotein outer membrane. The genome is approximately 190 kb. Smallpox and monkeypox viruses are both orthopoxviruses, and the smallpox vaccine is effective against mpox if given within 3–5 years before the disease is contracted. Symptoms of mpox in humans include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes. The virus is transmissible between animals and humans by direct contact to the lesions or bodily fluids. The virus was given the name monkeypox virus after being isolated from monkeys, but most of the carriers of this virus are smaller mammals.
An outbreak of human monkeypox began in May 2003 in the United States. By July, a total of 71 cases were found in six Midwestern states including Wisconsin, Indiana (16), Illinois (12), Kansas (1), Missouri (2), and Ohio (1). The cause of the outbreak was traced to three species of African rodents imported from Ghana on April 9, 2003, into the United States by an exotic animal importer in Texas. These were shipped from Texas to an Illinois distributor, who housed them with prairie dogs, which then became infected.
Suipoxvirus is a genus of viruses in the family Poxviridae and subfamily Chordopoxvirinae. Swine serve as natural hosts. There is only one species in this genus: Swinepox virus. Diseases associated with this genus include asymptomatic skin disease.
Pseudocowpox is a disease caused by the Paravaccinia virus or Pseudocowpox virus, a virus of the family Poxviridae and the genus Parapoxvirus. Humans can contract the virus from contact with livestock infected with Bovine papular stomatitis and the disease is common among ranchers, milkers, and veterinarians. Infection in humans will present with fever, fatigue, and lesion on the skin.
The 2022–2023 mpox outbreak in Switzerland is a part of the outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak started in Switzerland on 19 May 2022, with the country since then becoming one of the most affected in Europe.
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