Dictionary:
encephalitis le·thar·gi·ca (lə-thär'jĭ-kə)  |
[New Latin encephalītis lēthargica : encephalītis, encephalitis + Latin lēthargica, feminine of lēthargicus, sleepy.]
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Neurological Disorder:
Encephalitis lethargica |
Definition
Encephalitis lethargica is an inflammation of the brain caused by two trypanosomes (microscopic protozoan parasites). The illness, which can be fatal, is transmitted from one infected person to another by the tsetse fly. While it can occur globally, encephalitis lethargica is especially prevalent in Africa.
Description
Encephalitis lethargica is a vector-borne disease, meaning it is transmitted to a susceptible person by a living creature. The tsetse fly lives in moist vegetation near lakes and rivers and in grassy areas. People living near these regions are most susceptible the bite of a tsetse fly infected with the trypasosomes that cause encephalitis lethargica. The disease is also known as African trypanosomiasis, sleeping sickness, sleepy sickness, and von Economo's disease. Another form of the trypanosome-borne disease that occurs in North, Central, and South America is called Chagas disease.
Other subspecies of the trypanosome parasite can infect animals such as cattle, who can also harbor the trypanosomes that are infectious to humans.
Demographics
The form of encephalitis lethargica known as African trypanosomiasis occurs only in the sub-Saharan area of Africa. Tsetse flies are endemic in this region. However, for as yet unknown reasons, there are regions where tsetse flies are found, but the disease is absent. There have been several epidemics in Africa in the nineteenth and twentieth centuries. From 1896–1906, Uganda and the Congo basin were affected. A more wide-ranging epidemic occurred in 1920. Finally, an epidemic that began in 1970 is still occurring.
The latest epidemic is a result of the relaxed surveillance for the disease that happened with the near-eradication of the disease in the 1960s. As of 2004, the disease is a threat to more than 60 million people in 36 sub-Saharan African countries. In 1999, nearly 45,000 cases were reported, according to the World Health Organization (WHO). These cases represent individuals who were able to seek treatment and receive a definitive diagnosis at local health care centers. The actual number of cases was likely much higher, with estimates ranging from 300,000–500,000 cases actually occurring. In Africa, the disease occurs primarily in rural areas, where health care is least available. Poverty and encephalitis lethargica are associated with one another.
Causes and symptoms
The disease is caused by Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. The first species is found in central and West Africa. The infection is chronic; it persists for months or years with no display of symptoms. When they do emerge, the disease is at an advanced stage and the symptoms are more severe. T. brucei rhodesiense is found primarily in southern and eastern Africa. It causes an infection whose symptoms appear quickly (acute infection). This disease is more severe. Fortunately, the rapid appearance of symptoms offers more of a chance for quick detection.
Both trypanosomes are transferred to the tsetse fly when the fly obtains a blood meal from an infected person. The trypanosomes then multiply in the blood of the fly, and can be transferred to a susceptible person on whom the fly subsequently feeds.
The early symptoms of the disease include fever, severe headache, joint pain, and swelling of the lymph nodes. These symptoms can disappear and reoccur. Later, symptoms of what is called the neurological phase emerge and often include the characteristic symptoms of the disease: extreme weakness, paralysis of eye muscles, sleepiness, disruption of the sleep cycle, and a lapse into a deep and fatal coma. Transmission of the trypanosomes across the placenta from a pregnant woman to the fetus can occur. Typically this causes spontaneous abortion or death of the fetus.
Diagnosis
The most useful diagnostic sign is swollen cervical glands. This indicates the presence of the parasite. Populations can be screened for clinical signs of the disease (the early phase symptoms) and the use of tests that detect antibodies to the parasite in the blood. An early diagnostic sign of the bite of the tsetse fly is the appearance of a painful red sore (chancre) at the site of the bite.
A type of diagnosis called phase diagnosis can be used to help determine the level of advancement of the disease. Cerebro-spinal fluid is obtained by the technique of lumbar puncture and analyzed. Phase diagnosis requires medical and laboratory staff, and is typically done in a clinic. The long period, symptom-free period of a Trypanosoma brucei gambiense infection can complicate and delay diagnosis.
Treatment team
Physicians and nurses are the primary team involved in treating encephalitis lethargica. Additionally, public health workers in Africa and other areas affected with the tsetse fly receive help from health agencies throughout the world, who provide aid and strategies to reduce populations of the fly, educate local peoples to bite prevention methods, and treat affected individuals. Warring factions, with resulting political instability and hunger in the Sub-Saharan region of Africa have led to difficulty in controlling the spread of the tsetse fly and the disease.
Treatment
The choice of treatment depends on whether the disease is detected earlier or later in the infection. Early-stage infections can be treated using two drugs; suramine and pentamidine. An agreement between the World Health Organization and the drug's manufacturer (Aventis) has guaranteed continued production of the compounds.
Treatment of the later, neurological symptoms requires a drug that can cross the blood-brain barrier to reach the parasite. Currently only one drug (melarsoprol) is commercially available. The drug causes harsh side effects and itself has a fatal complication rate approaching 10%. As well, resistance of the trypanosomes to the drug is increasing. A second drug (eflornithine) exists, but is not commercially available. It is active only against Trypanosoma brucei gambiense. There is no vaccine for the disease.
Recovery and rehabilitation
Recovery from the early stage of the disease can be complete. Recovery from the neurological stage is typically incomplete, with varying degrees of impaired brain function often resulting. Once the person reaches the stage of coma, the disease is invariably fatal.
Clinical trials
As of early 2004, there were no clinical trials in progress for the study of encephalitis lethargica. Rather, efforts to increase screening of susceptible populations and to increase the supply of drugs is the identified priority for scientists working with the disease.
Prognosis
If treated early, a person with encephalitis lethargica can be cured. If not treated early, the prognosis is much less favorable due to resulting brain damage. Encephalitis lethargica is fatal if untreated.
Resources
BOOKS
Dumas, Michel, et. al. Progress in Human African Trypanosomiasis, Sleeping Sickness. New York: Springer Verlag, 1999.
Ramen, Fred. Sleeping Sickness and Other Parasitic Tropical Diseases (Epidemics). New York: Rosen Publishing Group, 2002.
OTHER
African Trypanosomiasis or Sleeping Sickness. World Health Organization. (January 27 2004). http://www.who.int/int-fs/en/fact259.html
East African Trypanosomiasis. Centers for Disease Control and Prevention. (January 27 2004). http://www.cdc.gov/ncidod/dpd/parasites/…osomisasis/factsht_ea_trypanosomiasis.htm
ORGANIZATIONS
Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311 or (800) 311-3435. http://www.cdc.gov.
World Health Organization (WHO). Avenue Appia 20, 1211 Geneva, Geneva, Switzerland. +41 22 791 21 11; Fax: +41 22 791-3111. info@who.int. http://www.who.int.
Brian Douglas Hoyle, PhD
| Medical Dictionary: encephalitis le·thar·gi·ca |
A viral epidemic encephalitis characterized by apathy, paralysis of an eye muscle, and extreme muscular weakness. Also called sleeping sickness, von Economo's disease.
| WordNet: encephalitis lethargica |
The noun has one meaning:
Meaning #1:
an encephalitis that was epidemic between 1915 and 1926; symptoms include paralysis of the extrinsic eye muscle and extreme muscular weakness
Synonyms: sleeping sickness, sleepy sickness, epidemic encephalitis, lethargic encephalitis
| Wikipedia: Encephalitis lethargica |
| Encephalitis lethargica | |
|---|---|
| Classification and external resources | |
 First described by Constantin von Economo. |
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| ICD-10 | A85.8 |
| ICD-9 | 049.8 |
| DiseasesDB | 32498 |
Encephalitis lethargica (EL) or von Economo disease is an atypical form of encephalitis. Also known as "sleepy sickness" or as "sleeping sickness" (though different from the sleeping sickness transmitted by the tsetse fly), EL was first described by the neurologist Constantin von Economo (1876-1931) in 1917,[1][2] EL attacks the brain, leaving some victims in a statue-like condition, speechless and motionless.[3] Between 1915 and 1926,[4] an epidemic of encephalitis lethargica spread around the world; no recurrence of the epidemic has since been reported, though isolated cases continue to occur.[5][6]
Contents |
Encephalitis lethargica is characterized by high fever, sore throat, headache, double vision, delayed physical and mental response, sleep inversion, catatonia and lethargy.[3] In acute cases, patients may enter a coma-like state (akinetic mutism). Patients may also experience abnormal eye movements ("oculogyric crises"),[7] parkinsonism, upper body weakness, muscular pains, tremors, neck rigidity, and behavioral changes including psychosis.
Postencephalitic Parkinsons' disease may develop after a bout of encephalitis, sometimes as long as a year after the start of the illness.
The cause of encephalitis lethargica is not known for certain.[8]
Research in 2004 suggested that the disease is due to an immune reaction. In this study, many of the people with encephalitis lethargica had experienced recent pharyngitis and the authors found some evidence linking the reaction to prior strep throat. They hypothesised that encephalitis lethargica, Sydenham's chorea and PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) are mediated by variations of the post-streptococcal immune response.[3]
There is also some evidence of an autoimmune origin with antibodies (IgG) from patients with EL binding to neurons in the basal ganglia and mid-brain. Western immunoblotting showed that 95% of EL patients had autoantibodies reactive against human basal ganglia antigens. By contrast, antibodies reactive against the basal ganglia were found in only 2-4% of child and adult controls (n = 173, P < 0.0001).[3][citation needed]
Some researchers believe that new data supports the influenza hypothesis,[9] while others consider this less likely.[3]
Haeman et al. (2009) at St. Jude Children's Research Hospital, USA, discovered that a H5N1 Bird Flu infection in mice causes severe loss of dopaminergic neurons 60 days after infection by provoking a destructive autoimmune response, thus suggesting the infection by certain strains of flu might increase the risk of Parkinson's disease in humans.[10] While Haeman et al. (2009) acknowledge research that shows the 1918 virus unlike H5N1 Bird Flu could not infect the brain, they propose that a distal infection might have provoked autoimmune mediated destruction of dopaminergic neurons while leaving no direct evidence of brain infection.[10] Thus, the 1918 Flu might have caused EL.
Treatment for encephalitis lethargica in the early stages is patient stabilization, which may be very difficult. There is little evidence so far of a consistent effective treatment for the initial stages, though some patients given steroids have seen improvement.[11] Other patients have been less fortunate, and the disease then becomes progressive, with evidence of brain damage similar to Parkinson's disease. Treatment is then symptomatic. Levodopa (L-DOPA) and other anti-parkinson drugs often produce dramatic responses. However in most of the patients who were given L-DOPA in the 1960s, the amelioration of the disease was short lived.
The course of encephalitis lethargica varies depending upon complications or accompanying disorders.
The discovery that L-DOPA could relieve some symptoms was described in the book Awakenings by Oliver Sacks in 1973. The book was used by Harold Pinter as the basis of his one-act play A Kind of Alaska, performed in 1982 starring Judi Dench. Awakenings is also the title of a 1990 movie starring Robin Williams and Robert De Niro based on the book. References to the disease are made in The Sandman: Preludes and Nocturnes, as cited in interviews with author Neil Gaiman, although the specific disease is unnamed within the work of fiction itself.
The disease is researched and mentioned in the Canadian television show ReGenesis, in the last few episodes of the second series.
It is also thought by some that encephalitis lethargica is the explanation for the symptoms of the afflicted in New England during the 1600s, which ultimately resulted in the Salem Witch Trials. The symptoms are consistent, and indeed "a similar epidemic with nearly exact symptoms (to those exhibited in Salem) swept the world from 1916 to 1930. This world-wide pandemic...encephalitis..."
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Neurological Disorder. Gale Encyclopedia of Neurological Disorders. Copyright © 2005 by The Gale Group, Inc. All rights reserved. Read more |
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| Medical Dictionary. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Read more |
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| WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. Read more |
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| Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Encephalitis lethargica". Read more |
