Algorithm(s)
PDF algorithm(s) available at www.arupconsult.com.
Human T-Lymphotrophic Virus Types I and II Testing Algorithm
Clinical Background
HTLV-I is etiologically associated with adult T-cell leukemia/lymphoma (ATLL), a demyelinating neurological disorder termed tropical spastic paraparesis (TSP) and with HTLV-I associated myelopathy (HAM).
Epidemiology
- Prevalence - 15-20 million globally infected with HTLV-I
- Endemic in Japan, Caribbean countries and Sub-Saharan Africa
- Age - median age is 50s
- HAM/TSP - 4th to 5th decade
- Sex
Organism
- HTLV-I and HTLV-II are human type C retroviruses
- Several subtypes exist that are geographically specific
- Majority of human infections is caused by subtype 1
- HTLV and AIDS
- HTLV-I does not cause AIDS
- Antibodies of HTLV-I have no relationship to antibodies of HIV-I, and antibodies to HTLV-I do not imply excess risk for AIDS
- HTLV-I virus is only remotely related to AIDS virus, HIV-I
- HTLV-I and HTLV-II are transmitted similarly to HIV-I and HIV-II
- Individuals with HTLV-I or HTLV-II may be coinfected with HIV due to common risk factors (sexual contact, intravenous drug use)
Risk Factors
- Cellular blood products - most efficient mode of transmission
- Breast milk - 20% of children of infected mothers will also become infected
- Sexual contact - associated with unprotected sex, multiple partners, presence of genital sores, sex exchanged for drugs or money
- Sharing of contaminated needles and syringes (intravenous drug users)
- Suspicion of perinatal transmission
- Poverty
Clinical Presentation
- ATLL
- Life-time risk for ATLL in those with HTLV-I antibodies is low;
- Even in countries with a high prevalence of HTLV-I (eg, Japan), the risk for developing ATLL is only 1-2%
- 4 types of ATLL - acute, chronic, smoldering, lymphoma
- Acute ATLL most common
- Rapidly fatal without treatment
- Pulmonary complications, opportunistic infections, sepsis
- Uncontrolled hypercalcemia may occur
- HAM/TSP
- Slowly progressive spastic paraparesis
- Develops in up to 4% of infected patients
- Caused by immune response to HTLV-I
See Also
Algorithm(s)
PDF algorithm(s) available at www.arupconsult.com.
Human T-Lymphotrophic Virus Types I and II Testing Algorithm
Diagnosis
Diagnosis
- Indications for testing - clinical presentation of ATLL or HAM; patient with appropriate clinical features
- Laboratory testing
- HTLV-I antibody testing
- HTLV-II antibodies significantly cross-react to HTLV-I antigens
- Populations such as parenteral drug abusers infected with HTLV-II may test positive for HTLV-I antibodies due to antibody cross-reactivity
- Asymptomatic patients with HTLV-I antibodies
- May be infected and should not donate blood
- May not have ATLL or TSP and may not develop ATLL, HAM or TSP
- Proviral loads correlate with infectivity
Differential Diagnosis
- HAM/TSP
- ALS
- HIV
- Multiple sclerosis
- Myopathies
- Myositis
- Paraneoplastic Syndromes
- Polio
- ATLL
Algorithm(s)
PDF algorithm(s) available at www.arupconsult.com.
Human T-Lymphotrophic Virus Types I and II Testing Algorithm
Tests generally appear in the order most useful for common clinical situations
| Test name: Human T-Lymphotrophic Virus Types I/II Antibodies with Reflex to HTLV I/II Confirmation
|
| ARUP #: 0051164 |
| Methodology: Enzyme Immunoassay/Western Blot
|
| Use: Screen for antibodies to Human T-Lymphotropic Virus Types I and II |
| Test name: Human T-Lymphotrophic Virus Types I/II Antibodies, Western Blot
|
| ARUP #: 0020642 |
| Methodology: Western Blot
|
| Use: Confirm antibody test results for a positive screening test (HTLV Types I and II) performed in another lab |
| Follow-up: If results are untypable or indeterminate, repeat test in 3 months |
References
General References
Gallo RC. History of the discoveries of the first human retroviruses: HTLV-1 and HTLV-2. Oncogene.
2005;
24(
39):
5926-5930.
Lee TH, Chafets DM, Busch MP, Murphy EL. Quantitation of HTLV-I and II proviral load using real-time quantitative PCR with SYBR Green chemistry. J Clin Virol.
2004;
31(
4):
275-282.
Matutes E. Adult T-cell leukaemia/lymphoma. J Clin Pathol.
2007;
60(
12):
1373-1377.
Proietti FA, Carneiro-Proietti AB, Catalan-Soares BC, Murphy EL. Global epidemiology of HTLV-I infection and associated diseases. Oncogene.
2005;
24(
39):
6058-6068.
Roucoux DF, Murphy EL. The epidemiology and disease outcomes of human
T-lymphotropic virus type II. AIDS Rev.
2004;
6(
3):
144-154.
Shuh M, Beilke M. The human T-cell leukemia virus type 1 (HTLV-1): new insights into the clinical aspects and molecular pathogenesis of adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-associated myelopathy (TSP/HAM). Microsc Res Tech.
2005;
68(
3-4):
176-196.
Takenouchi N, Yamano Y, Usuku K, Osame M, Izumo S. Usefulness of proviral load measurement for monitoring of disease activity in individual patients with human T-lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis. J Neurovirol.
2003;
9(
1):
29-35.
Taylor G. Molecular aspects of HTLV-I infection and adult T-cell leukaemia/lymphoma. J Clin Pathol.
2007;
60(
12):
1392-1396.
Medical Reviewers
Slev, Patricia , Ph.D. Assistant Medical Director, Hepatitis and Retrovirus Serology and Special Chemistry at ARUP Laboratories
Comprehensive Review: September 2008
Last Update: September 2008
