Name
PARVOVIRUS B 19 INFECTION
DESCRIPTION
DETAIL
CAUSES β’ Small (22-24 nm), nonenveloped, single stranded DNA virus. It is the only known parvovirus to infect humans and belongs to the family Parvoviridae and was discovered in 1975. β’ In EI, the period of viral shedding precedes the development of the rash, suggesting the pathogenesis of the rash is immune related β’ In fetal infection, maternal viremia with transplacental passage is the source of infection. Respiratory secretions and rarely blood products are sources of human spread of virus. -------------------------------------------------------------------------- DIFFERENTIAL DIAGNOSIS β’ Rubella β’ Enteroviral disease β’ Systemic lupus erythematosus β’ Drug reaction β’ Lyme disease β’ Rheumatoid arthritisLABORATORY β’ Anemia, neutropenia and agranulocytosis may be noted β’ Serum IgM antibody to B19 is usual method of confirming diagnosis. During acute infection B19 IgM persists for 1-2 months (less in neonates). β’ To exclude congenital B19 in infants with negative B19 IgM, one must follow an infantβs B19 IgG serology in the first year of life β’ Maternal serum alpha-fetoprotein may be increased in fetuses with hydrops fetalis β’ The most reliable technique, less commonly used, is detection of viral DNA in fetal blood SPECIAL TESTS β’ Antigen detection in tissue or fluids by nucleic acid hybridization or polymerase chain reaction is available on an investigational basis in many academic centers β’ B19 cannot be grown in traditional tissue culture systems, but can be detected by enzyme immunoassays, immune fluorescence and Western blot assays IMAGING Maternal infection - fetal ultrasound DIAGNOSTIC PROCEDURES Amniotic fluid and chorionic villus sampling may be useful diagnostically in investigation of some maternal infections
TYPENOTES
RISK FACTORS: Aplastic crisis - increased RBC turnover (e.g., sickle cell anemia), Chronic anemia - immunodefi cient individuals, Intrauterine infection - pregnant, nonimmune womanAPPROPRIATE HEALTH CARE β’ Outpatient management for EI β’ Inpatient for aplastic crisis, other severe manifestations β’ Intrauterine transfusion lowers mortality risk in severely hydropic fetuses ACTIVITY β’ Unrestricted for EI β’ Arthritis patients may require physical therapy/exercise program DIET No special diet PATIENT EDUCATION β’ Patients with chronic hemolytic diseases should be aware of risks for aplastic crisis if exposed to EI β’ Pregnant women should avoid exposure to patients with active or chronic infections. However, most adults have already had inapparent infection are therefore not at risk. Exclusion of pregnant women from the workplace where EI is occurring is not recommended. β’ Children with symptoms are not infectious and may attend child care or school (e.g., transmission of virus occurs in the asymptomatic interval between infection and symptom expression) β’ Immunocompromised patients (eg, receiving chemotherapy) are at increased risk of infection Parvovirus B19 infection DRUG(S) OF CHOICE β’ No therapy needed usually β’ Immune globulin (IVIG) IV has been used successfully for refractory anemias, especially with AIDS β’ Cessation of immunosuppressive therapy has allowed some patients to clear chronic infections β’ Red blood cell transfusions may be required for aplastic crisis β’ Anti-inflammatory agents may alleviate arthritic symptoms ALTERNATIVE DRUGS None PATIENT MONITORING Periodic blood counts for anemic patients PREVENTION/AVOIDANCE β’ Standard hygienic practices can minimize spread β’ Because EI is so common, it is not possible to avoid exposure completely. Also, period of contagion is before clinical illness (rash) appears. β’ Pregnant health care workers should avoid caring for patients with aplastic crises β’ Pregnant child care workers are at some increased risk; however, exclusion from the work place will not eliminate this risk, and therefore is not recommended POSSIBLE COMPLICATIONS Rare, but more commonly seen in adults than children β’ Arthritis β’ Persistent anemia β’ Hemophagocytic syndrome β’ Pneumonitis β’ Encephalopathy β’ Stroke β’ Reports of congenital anomalies and chronic fatigue syndrome, but no clear-cut association β’ Glomerulonephritis and other renal diseases have been reported in both immunocompromised and immunocompetent patients β’ Nephrotic syndrome β’ Hepatitis β’ Neuropathies β’ Rarely associated temporally in Henoch-Schonlein purpura (HSP) or vasculitis diseases in children β’ Myocarditis/pericarditis β’ Lupus-like presentation β’ Left ventricular dysfunction EXPECTED COURSE/PROGNOSIS β’ Usually self-limited β’ Joint symptoms subside in weeks (often by 2 weeks) β’ About 20% of infections result in delayed virus elimination and viremia persisting for several months to years β’ Full recovery from aplastic crisis in 2-3 weeks
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
SERUM IGG, SERUM IGM, COMPLETE BLOOD COUNT, ULTRA SOUND EXAM