Conditions & Diseases: Brain & Nervous System

Encephalitis

See Also:
Encephalitis: Introduction
Encephalitis: Types
Encephalitis: Causes & Risk Factors
Encephalitis: Signs & Symptoms
Encephalitis: Medical Tests & Diagnosis Methods
Encephalitis: Treatment & Prevention Options

Causes & Risk Factors

Viral infection spread due to insect bites (mosquito or tick bite), or human-to-human contact or animal bite causes encephalitis. The viruses that spread encephalitis are as follows:

• Herpes Simplex Virus (the cold sore virus)
• Rubeola (measles)
• Varicella (chicken pox)
• Influenza
• Rubella (german measles)
• Polioviruses
• Enteroviruses (tummy bugs)
• Epstein-Barr virus (EBV) (glandular fever)
• Mumps (4)
• Cytomegalovirus
• HIV
• Herpes zoster (shingles)
• Herpes B
• Rabies
• Mosquito-borne viruses (arboviruses) (5).

Insects bite mammals, domestic animals and birds, leading to spreading of the infection and causing encephalitis. Some examples are as follows:

• West Nile encephalitis (or West Nile fever)
• Japanese Encephalitis
• Tick Borne Encephalitis
• Murray Valley Encephalitis
• California encephalitis
• St Louis encephalitis
• Western equine encephalitis
• Eastern equine encephalitis
• Colorado tick fever (4).

Bacterial causes include Mycobacterium tuberculosis (TB) and Bartonella henselae (cat scratch). Rarely, encephalitis is also be triggered by a brain injury, brain tumor, drug reactions, lead poisoning or vaccine reaction (6).

Some of the risk factors of encephalitis are as follows:

• Age: Certain types of encephalitis are prevalent or severe in young children or older adults.
• Weakened Immune System: People suffering from AIDS/HIV and undergoing cancer therapies or organ transplantation are susceptible to encephalitis.
• Geographic Regions: People visiting or living in areas prevalent with mosquito-borne viruses are at increased risk being infected with encephalitis.
• Outdoor Activities: People with hobbies of gardening, jogging, playing golf or bird watching need to exercise extra care during an encephalitis outbreak.
• Season: Mosquito-borne diseases are more prevalent during summer months in the US since it is the prime mating time for birds and mosquitoes, thus the risk of getting infected is more during this season (7).

See Also:
Encephalitis: Introduction
Encephalitis: Types
Encephalitis: Causes & Risk Factors
Encephalitis: Signs & Symptoms
Encephalitis: Medical Tests & Diagnosis Methods
Encephalitis: Treatment & Prevention Options

Article by Kona Vishnu, MS
Medical Writer,
OmniMedicalSearch.com