DISEASE
Infectious Mononucleosis
Alternate names: I.M., human herpesvirus 4 (HHV-4), glandular fever, Pfeiffer’s disease, Epstein-Barr infection, “mono.”

AUTHOR
Erica Rome, BIOL 230, Spring 2009

CAUSATIVE AGENTS
The Epstein-Barr virus (EBV) measures between 180 and 200nm long and has an envelope. Its genome consists of double-stranded, linear DNA with an icosahedral capsid measuring between 95 and 105nm in diameter. A herpesvirus (Herpesviridae), EBV belongs to the subfamily Gammaherpesvirinae, the Lymphocryptovirus genus and the human herpesvirus 4 (HHV-4) species.

EPIDEMIOLOGY
Since there is no vaccine or preventative treatment, most people have been exposed to EBV, making it one of the most common viruses in humans. Often, exposure does not result in a serious illness or symptoms: the immune system manufactures EBV antibodies and the patient has no awareness of having been infected.

Post-symptomatically, the Epstein-Barr virus stays dormant in the blood cells and throat for the remainder of the life of the patient. This makes it possible for the virus to reactivate. It is usually asymptomatic upon reactivation, but the reactivated virus can be detected in the saliva.

It has been suggested that multiple sclerosis (def) patients have significantly high levels of anti-EBV antibodies years before showing any symptoms of MS, but it is also believed that MS is a complex illness with more than one complicating factor, and perhaps even more than one infection.

Studies suggest EBV's involvement in several other diseases, including Burkitt's lymphoma (def), non-Hodgkin’s lymphoma in AIDS patients, nasopharyngeal (def) cancer, certain inflammatory diseases of the mouth (irreversible pulpitis (def) and apical (def) periodontitis (def), some post-transplant diseases, leiomyomas (def) and leiomyosarcomas (def) of children with AIDS. (EBV seems to have no association with smooth-muscle tumors in HIV-negative patients.)

TRANSMISSION
Infectious mononucleosis is transmitted via saliva and can be transmitted by a person who is or is not symptomatic, making transmission nearly impossible to prevent. All ages are susceptible, but when a teenager is exposed to the virus, there is a higher likelihood (35% -50%) of advancement to I.M. (thus mono’s affectionate name, “the kissing disease”).


SIGNS AND SYMPTOMS
Common symptoms are fever, sore throat, lymphadenopathy (def). Less common are hepatosplenomegaly (def), problems of the heart and nervous system are observed. Fatigue and muscle aches may continue for several months after infection resolution.

An initial diagnosis of I.M. is conferred when fever, sore throat and swollen lymph nodes present simultaneously. A confirmed diagnosis will include a positive “mono spot” (def) test, elevated white count (including a high level of atypical lymphocytes), and/or a positive Paul-Bunnell heterophile antibody (def) test result.

False negatives are possible (up to 15%), and are more common early in the infection’s course. If the patient has another infection (toxoplasmosis, streptococcus, cytomegalovirus, etc.), this may skew the heterophile test causing a false negative for EBV.


PREVENTION AND TREATMENT
There is currently no treatment for the Epstein-Barr infection. Symptoms often resolve in less than 4 months. If symptoms last longer than 6 months, some clinicans use the term “chronic EBV infection” while others search for non-EBV causes for the malaise.

Symptomatic treatment includes hydration, pain relievers, drugs that reduce fever, warm salt water gargles and rest. Corticosteroids may be helpful for EBV-infected patients with respiratory or pharyngeal issues. Antiviral drugs and antihistamines are not recommended.

Athletes are advised not to participate in contact or collision sports for four or more weeks after experiencing initial symptoms.

BIBLIOGRAPHY

CDC. National Center for Infectious Diseases. Epstein-Barr Virus and Infectious Mononucleosis. Retrieved March 14, 2009 from
http://cdc.gov/ncidod/diseases/ebv.htm

Medline Plus. Infectious Mononucleosis. Retrieved March 2009 from http://vsearch.nlm.nih.gov/vivisimo/cgi-bin/query-meta?v%3Aproject=medlineplus&query=EBV&x=0&y=0

NIH X-Plain Tutorial: Epstein-Barr Virus, ibid.
http://www.nlm.nih.gov/medlineplus/tutorials/epsteinbarrvirusmono/htm/index.htm

Boyles, Salynn (rev. Chang, Louise). Epstein-Barr Virus May Trigger Multiple Sclerosis; Elevated Antibodies Could Predict Disease. WebMD. Retrieved March 14, 2009 from
http://www.webmd.com/multiple-sclerosis/news/20060410/epstein-barr-virus-may-trigger-ms

Ebell, ML. Things Ko Know About Infectious Mononucleosis. American Family Physician, October 4, 2004, 70 (7) : 1279-87. Retrieved March 14, 2009 from http://www.ncbi.nlm.nih.gov/pubmed/15508538

Science Daily. Epstein-Barr Virus Associated With Inflammatory Diseases Of The Mouth. November 13, 2008. Retrieved March 14, 2009 from
http://www.sciencedaily.com/releases/2008/11/081110171344.htm

Kaiser, Gary. The role of viruses in tumor production. Lecture E-Text for Community College of Baltimore County(Catonsville, Maryland)’s Microbiology Course (BIOL 230). Unit 3, Section IV/F/5.
http://student.ccbcmd.edu/courses/bio141/lecguide/unit3/viruses/tumor.html

McClain, Kenneth; Leach, Charles; Jenson, Hal; Joshi, Vijay; Pollock, Brad; Parmley, Richard; DiCarlo, Frederick; Chadwick, Ellen; Murphy, Sharon; “Association of Epstein-Barr Virus with Leiomyosarcomas in Young People with AIDS.” New England Journal of Medicine, January 5, 1995, Volume 332: 12-18. Retrieved March 14, 2009 from http://content.nejm.org/cgi/content/abstract/332/1/12

Carilion Clinic (Virginia), Infectious Mononucleosis. Retrieved March 14, 2009 from
http://www.carilionclinic.org/Carilion/P02530

MicrobiologyBytes: Herpesviruses. Retrieved March 14, 2009 from
http://www.microbiologybytes.com/virology/Herpesviruses.html

Bennett, Nicholas, Domachowske, Joseph, Rothschild, Bruce, Mononucleosis and Epstein-Barr Infection. Emedicine/webMD. Retrieved March 14, 2009 from http://emedicine.medscape.com/article/963894-overview