Human T-cell lymphotropic virus (HTLV-1)



 A Human T-cell lymphotropic virus (HTLV-1) a significant pathologic human retrovirus.


HTLV-1 infection immortalizes CD4 T cells.


HTLV-1 is estimated to affect 5 million to 10 million people worldwide.


Highly endemic areas include Japan, sub-Saharan Africa, the Caribbean islands, and South America, especially Brazil, Colombia, Chile, and Peru.


HTLV-1 is predominantly spread through prolonged breastfeeding, unprotected sexual intercourse, and contamination of blood products.


It maybe the most oncogenic virus.


Most carriers are asymptomatic


It can cause two fatal diseases, Adult T cell leukemia/lymphoma (ATL)  and HTLV-1 associated myelopathy/tropical spastic paraparesis/TSP.


Adult T cell leukemia/lymphoma (ATL) is a peripheral T-cell neoplasm associated with HTLV-1, and it is seen in 2% to 4% of those infected with the virus.


Adult T cell leukemia/lymphoma (ATL) symptoms include abdominal pain, ascites, diarrhea, jaundice, pleural effusion, cough, sputum, fever, unconsciousness, and opportunistic infections. 


ATL findings include: lymphadenopathy, splenomegaly, hepatomegaly, hypercalcemia, skin lesions, and pulmonary lesions. 


ATL classifications are acute, lymphoma, chronic, and smoldering. 


Acute leukemia and lymphoma have median survival rates of 8.3 and 10.6 months, respectively, while chronic and smoldering have median survival rate of 31.5 and 55.0 months, respectively.


ATL usually develops after a 3- to 5-decade latency period and is rarely seen in those infected during adulthood.


The  risk of ATL from perinatal HTLV-1 infection has been estimated to be as high as 25%.


HTLV-1 associated myelopathy/tropical spastic paraparesis/TSP (HAM/TSP) primarily affects the spinal cord and presents similarly to primary progressive multiple sclerosis (PPMS). 


Initial symptoms of HAM/TSP are usually gait disturbance, falling, lower-extremity weakness, back pain, bowel and bladder dysfunction, hyperreflexia, and/or sexual dysfunction.


There is usually preservation of upper-extremity strength.


Unlike ATL, HAM/TSP usually develops after an infection in adulthood secondary to blood transfusion or organ transplantation.


Many countries, including the United States, do not screen organ donors for HTLV-1. 


The  risk of HAM/TSP is close to 10% in posttransplant cases.


HAM/TSP usually manifests over several decades in perinatal infections, and can  lead to morbidity in less than 5 years in posttransplant cases.


Physical examination findings   in HAM/TSP  can include spastic gait, lower-extremity weakness, usually worse proximally, and hyperreflexia.


Diagnosing HAM/TSP: a 4-step process. 


clinical signs 


serologic confirmation of HTLV-1 


cerebrospinal fluid (CSF) detection of anti–HTLV-1 antibodies 


Exclusion of other disorders that present similarly.


The differential diagnosis for HAM/TSP: includes MS, neuromyelitis optica, spinal cord compression, transverse myelitis, collagen vascular disease, Sjogren’s syndrome, hereditary spastic paraparesis, primary lateral sclerosis, vitamin B12 and folate deficiency, HIV-associated vacuolar myelopathy, neurosyphilis, and Lyme disease.


Numerous other inflammatory disorders occur as a result of HTLV-1 infection: uveitis, conjunctivitis, sicca syndrome, interstitial keratitis, pulmonary diseases, infective dermatitis, arthritis, myositis, Sjögren syndrome, Hashimoto thyroiditis, Graves disease, and polyneuropathies.


HTLV-1 associated dermatitis is the most common manifestation in children. 


Patients with ATL may develop opportunistic infections or infestations such as with Strongyloides stercoralis, scabies, tuberculosis, and leprosy.


Treatment of ATL remains an active area of research, and  should be referred for clinical trials when possible. 


In CD30-positive cases the A+CHP regimen has been shown to provide median progression-free survival of 48.2 months.


Dose-adjusted EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) is recommended in CD30-negativ cases.


The combination of zidovudine and interferon-alfa has been used with some success in various subtypes of ATL.


Other regimens include CHOEP (cyclophosphamide, doxorubicin, vincristine, etoposide, and prednisone), and hyper-CVAD (cyclophosphamide, vincristine, doxorubicin, and dexamethasone) alternating with high-dose methotrexate and cytarabine. 


Second-line treatment options include single-agent brentuximab vedotin, lenalidomide, or mogamulizumab regimens.


HAM/TSP treatment is predominantly symptomatic. 


Corticosteroids have been reported to decelerate progression of the disease.



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