Human T-cell lymphotropic virus infection

Human T-cell lymphotropic virus infection causes Adult T-cell leukemia/lymphoma (ATL) and HTLV-associated myelopathy/tropical spastic paresis (HAM/TSP). HTLV-1 causes adult T-cell leukemia/lymphoma (ATL) or HTLV-1 associated myelopathy (HAM/TSP) in 5% to 10% of HTLV-1 infected individuals.

CASES/YEAR
105,000 (US); 7,500,000 (Global)
AGENT TYPE
Viruses
OTHER NAMES
HTLV-1 infection; HTLV-2 infection; Adult T-cell leukemia/lymphoma (ATL); HTLV-associated myelopathy/tropical spastic paresis (HAM/TSP);
ACUITY
Subacute/Chronic
INCUBATION
50-60 years for signs and symptoms of disease; [CCDM, p. 303] Most HAM/TSP cases occur in adults in the 30- to 50- year age group, but cases in children as young as 3 have been reported; [Cecil, p. 2204]
INITIAL SYMPTOMS
Asymptomatic;
PRECAUTIONS
There is a 30% to 40% risk of transmission in endemic areas by mother-to-child transmission or prolonged breastfeeding. Also transmitted by transfusions, sexual contact, and solid organ transplantation. [CCDM, p. 303]
COMMENTS
HTLV-1 causes adult T-cell leukemia/lymphoma (ATL) or HTLV-1 associated myelopathy (HAM/TSP) in 5% to 10% of HTLV-1 infected individuals. Disease risk is highest with proviral load >4% in Japan and >10% in the Caribbean. HAM/TSP resembles progressive multiple sclerosis. Other diseases caused by HTLV-1 are polymyositis, uveitis, and infective dermatitis. "HTLV-2, which targets CD8+ T-lymphocytes, is not associated with clinical disease." [CCDM, p. 302-3] HTLV-1 and HTLV-2 viruses are transmitted efficiently by sexual intercourse, breast feeding, transfusion, and injection drug use. Efficiency of transplacental transmission is thought to be low for HTLV-1 and probable for HTLV-2. There is strong evidence that HTLV-1 causes ATL, HAM, dermatitis, and uveitis in adults. There is strong evidence that HTLV-2 causes HAM in adults. "Surveys from the Ivory Coast, Ghana, Nigeria, Democratic Republic of Congo, Kenya, and Tanzania document that rates of HTLV-1 seropositivity are similar to those in the Caribbean region (5% to 14%), but more and better data from sub-Saharan Africa are needed." Similar rates exist in southern Japan and South America with foci of seropositivity in Brazil, Colombia, Peru, Chile, French Guiana, Guyana, and Surinam. HTLV-I/II antibody positive rates in the US are up to 0.3 to 0.4 per 1000 based on blood supply screening. HTLV-II is highly prevalent in intravenous drug users in the US and Italy and also in various Amerindian populations in the Western Hemisphere. [PPID, p. 2190-1] HTLV-2 infections occur in Native Americans and West Africans. Most HTLV-2 infections in the US occur in injection drug users. More than 1/2 of HTLV infections in blood donors are due to HTLV-2. Women are about twice as likely to develop HAM. [Cecil, p. 2204] "Infection with human T-lymphotropic virus (HTLV) 1 or 2 can cause T-cell leukemias and lymphomas, lymphadenopathy, hepatosplenomegaly, skin lesions, and immunocompromise. Some HTLV-infected patients develop infections similar to those that occur in HIV-infected patients. HTLV-1 can also cause myelopathy/tropical spastic paraparesis." TSP/HAM develops over several years with loss of proprioception, Achilles tendon reflexes, and bladder control. Diagnosis is likely if the ratio of antibody titers in CSF/serum is >1 or PCR of CSF is positive. TSP/HAM is most common among prostitutes, IV drug users, hemodialysis patients, and people from endemic areas. [Merck Manual, p. 1628; 2033] Patients infected with HTLV-1 have a lifetime risk of 5% for leukemia and 0.5-2% for spastic paraparesis. Leukemia patients may present with lymphadenopathy, skin plaques/nodules, or hypercalcemia. [ABX Guide]
DIAGNOSTIC
Confirmed by testing for antibodies to HTLV-1; PCR testing can detect infection and determine type; [Cecil, p. 2203-4]
SCOPE
Both HTLV-1 and ATL are endemic in southwestern Japan and the Caribbean; [Harrisons, p. 298] Endemic in central Africa, Caribbean, parts of S. America, Japan & other focal areas; [PPID, p. 2185]
SIGNS & SYMPTOMS
  • G hepatomegaly
  • H lymphadenopathy
  • H splenomegaly
  • N muscle weakness
  • N paresthesia
  • S papules or plaques
  • S skin or subcutaneous nodule
  • *cancer
  • *myelitis
  • *paralysis
  • *uveitis
ANTIMICROBIC

No

VACCINE

No

ENTRY
Needle (Includes Drug Abuse), Scalpel or Transfusion, Sexual Contact
SOURCE
Person-to-Person
RESERVOIR
Human
RISK FACTORS
  • Have a blood transfusion
  • Injection drug users
  • Travel to endemic area
TREATMENT
Treatment of asymptomatic HTLV carriers is not indicated. [PPID, p. 2198]
DRUG LINK
REFERENCES FOR CASES/YEAR
1. (US) Seropositive rates are up to 0.3 to 0.4 per 1000 based on large-scale blood supply screening. [PPID, p. 2190] Calculate: 0.35/1000 X 300 million = 105,000;
2. (Global) HTLV-1 infects 5-10 million people; 2-6% develop adult T-cell leukemia/lymphoma (ATL) and 1 to 2% develop HTLV-1-associiated myelopathy/tropical spastic paraparesis (HAM/TSP); [Cecil, p. 2202, 2204]