Ectromelia is a viral disease that primarily affects mice, presenting a significant concern in specific environments. Understanding this disease is important for those involved in mouse care and research.
What is Ectromelia?
Ectromelia is a viral disease caused by the Ectromelia virus (ECTV), also known as mousepox virus. This virus belongs to the Poxviridae family and is classified within the Orthopoxvirus genus. The natural and primary host for ECTV is mice, specifically species within the Mus genus, including both laboratory and wild mice.
The virus has a history in laboratory animal science, first discovered in 1930 in laboratory mouse colonies in England, coinciding with the initial use of mice as animal models. It later spread to various regions, including Europe, Japan, China, and the USA. Ectromelia virus is the only poxvirus known to naturally cause disease in mice.
Recognizing Ectromelia
Mice infected with ectromelia virus often display observable signs, particularly on their extremities. These include swelling, redness, and eventual ulceration, especially on the feet, tail, ears, and snout. Scab formation typically follows these lesions.
Systemic signs may also be present, such as lethargy, a ruffled coat appearance, and noticeable weight loss. In some cases, diarrhea can occur. The disease can manifest in different forms, including acute, subacute, and chronic presentations, with the severity and duration of symptoms varying depending on the mouse strain.
In susceptible mouse strains, such as A, CBA, C3H, BALB/c, and DBA/2, mortality rates can be as high as 80-90%, sometimes with rapid death occurring before other clinical signs become apparent. Mice that survive the acute phase may develop a generalized rash, and severe infection of the feet and tail can lead to necrosis and even amputation, which gives the disease its name. Internally, necropsy can reveal extensive necrosis in the spleen, liver, lymph nodes, and thymus, as well as mucosal erosions in the small intestine.
How Ectromelia Spreads
Ectromelia virus is highly contagious among mice, spreading through multiple routes. Direct contact between infected and susceptible animals is a primary mode of transmission, often occurring through skin lesions, feces, or urine. Skin abrasions are considered a main route of entry for the virus.
Indirect transmission is also common, involving contaminated inanimate objects, known as fomites, such as bedding, cages, water bottles, and other equipment. The virus is known for its ability to persist in the environment; for example, it can survive for 11 days at room temperature in blood, and has been found in scabs and feces for up to 16 weeks post-infection. Transmission can also occur through contaminated biological products, such as tumor cells or serum, from infected animals. While less common, aerosol transmission is also possible with large-droplet aerosols.
Ectromelia and Human Health
Ectromelia virus is not known to infect humans and is not classified as a zoonotic disease. The virus’s impact is confined to its natural host species.
Its primary significance lies within laboratory animal facilities, where it can disrupt research and lead to colony losses. The focus of control measures remains on animal welfare and research integrity within specific environments.
Controlling Ectromelia
Controlling ectromelia outbreaks in mouse colonies, particularly within research facilities, relies on stringent biosecurity measures. This includes quarantining all new animals before introducing them to existing colonies, allowing for comprehensive health screening through methods like serologic testing or PCR. Regular health monitoring and surveillance programs are implemented to identify early signs of disease, with immediate stringent quarantine measures instituted if mousepox is suspected.
Strict hygiene protocols, including thorough cleaning and disinfection of all facilities and equipment, are important to prevent environmental contamination. Specific disinfectants like gaseous formalin or vaporized hydrogen peroxide are often used, and materials may be discarded as hazardous waste or autoclaved. These methods, along with desiccation and detergents, effectively inactivate the virus.
Vaccination strategies are available and often employed for laboratory mouse colonies, providing protection against the virus. These vaccines help prevent disease and reduce the severity of infection.
References
1. [https://vertexaisearch.googleapis.com/v1/projects/1066734591783/locations/global/collections/default_collection/dataStores/ectromelia-virus/servingConfigs/default_serving_config:search?query=Ectromelia%20virus%20classification%20host%20historical%20significance&pageSize=3](https://vertexaisearch.googleapis.com/v1/projects/1066734591783/locations/global/collections/default_collection/dataStores/ectromelia-virus/servingConfigs/default_serving_config:search?query=Ectromelia%20virus%20classification%20host%20historical%20significance&pageSize=3)
2. [https://vertexaisearch.googleapis.com/v1/projects/1066734591783/locations/global/collections/default_collection/dataStores/ectromelia-virus/servingConfigs/default_serving_config:search?query=Ectromelia%20virus%20symptoms%20signs%20mice%20progression%20acute%20subacute%20chronic&pageSize=3](https://vertexaisearch.googleapis.com/v1/projects/1066734591783/locations/global/collections/default_collection/dataStores/ectromelia-virus/servingConfigs/default_serving_config:search?query=Ectromelia%20virus%20symptoms%20signs%20mice%20progression%20acute%20subacute%20chronic&pageSize=3)