Thomas J. Török

Pediatric Hospitalizations for Croup (Laryngotracheobronchitis): Biennial Increases Associated with Human Parainfluenza Virus 1 Epidemics

Croup is a common manifestation of respiratory tract infection in children, and human parainfluenza virus 1 (HPIV-1) is the agent most commonly associated with croup. In the United States, HPIV-1 produces a distinctive pattern of biennial epidemics of respiratory illness during the autumn months of odd-numbered years. National Hospital Discharge Survey data for croup hospitalizations among patients <15 years old between 1979 and 1993 were examined along with laboratory-based surveillance data on HPIV-1 activity in the United States. The mean annual number of croup hospitalizations was 41,000 (range, 27,000-62,000/year). Ninety-one percent of hospitalizations occurred among children <5 years of age. Minor peaks in croup hospitalizations occurred each year in February, and major peaks occurred in October of odd-numbered years, coincident with peak HPIV-1 activity. Each biennial epidemic of HPIV-1 was associated with 18,000 excess croup hospitalizations nationwide.

Multiple primer pairs for polymerase chain reaction (PCR) amplification of human parvovirus B19 DNA

Human parvovirus B19 is the etiologic agent of erythema infectiosum and transient aplastic crisis in patients with hemolytic anemias and has been associated with fetal death, arthritis, and chronic anemia. Acute B19 infection is best diagnosed by detection of IgM antibodies, whereas the diagnosis of chronic infection often requires the sensitivity of PCR to demonstrate presence of virus over time. To improve our ability to detect B19 DNA by polymerase chain reaction (PCR), we evaluated 19 primers combined into 16 different primer pairs for their ability to detect temporally and geographically diverse B19 isolates. All 16 pairs reacted with all isolates tested but with different sensitivity. Sequence analysis showed few nucleotide changes compared with published sequences. These changes did not explain observed differences in sensitivity between primer pairs. The most sensitive primer pairs detected 350 to 3500 DNA copies after 35 cycles. A second amplification cycle with nested primers improved the sensitivity 100-fold. These 16 primer pairs provide the diagnostic virologist with multiple options for B19 PCR assays.

Visualizing geographic and temporal trends in rotavirus activity in the United States, 1991 to 1996

BACKGROUND Rotavirus is the leading cause of severe pediatric gastroenteritis worldwide. A vaccine may soon be licensed for use in the United States to prevent this disease. To characterize US geographic and temporal trends in rotavirus activity, we made contour maps showing the timing of peak rotavirus activity. METHODS From July, 1991, through June, 1996, 79 laboratories participating in the National Respiratory and Enteric Virus Surveillance System reported on a weekly basis the number of stool specimens that tested positive for rotavirus. The peak weeks in rotavirus detections from each laboratory were mapped using kriging, a modeling technique originally developed for geostatistics. RESULTS During the 5-year period 118,716 fecal specimens were examined, of which 27,616 (23%) were positive for rotavirus. Timing of rotavirus activity varied by geographic location in a characteristic pattern in which peak activity occurred first in the Southwest from October through December and last in the Northeast in April or May. The Northwest exhibited considerable year-to-year variability (range, December to May) in the timing of peak activity, whereas the temporal pattern in the remainder of the contiguous 48 states was relatively constant. CONCLUSION Kriging is a useful method for visualizing geographic and temporal trends in rotavirus activity in the United States. This analysis confirmed trends reported in previous years, and it also identified unexpected variability in the timing of peak rotavirus activity in the Northwest. The causes of the seasonal differences in rotavirus activity by region are unknown. Tracking of laboratory detections of rotavirus may provide an effective surveillance tool to assess the impact of a rotavirus vaccination campaign in the United States.

Progressive Multifocal Leukoencephalopathy in the United States, 1979–1994: Increased Mortality Associated with HIV Infection

To examine trends in progressive multifocal leukoencephalopathy (PML) mortality in the United States, we analyzed PML death rates and deaths for 1979 through 1994, using US multiple cause-of-death data. During the 16-year study period 3,894 PML deaths were reported. The age-adjusted death rate increased more than 20-fold, from less than 0.2 per million persons before 1984 to 3.3 per million persons in 1994. The increase was attributable to infection with human immunodeficiency virus (HIV) which was recorded on 2,267 (89.0%) of 2.546 death records from 1991 through 1994. PML age-adjusted death rates increased abruptly for all males beginning in 1984 and for black females in 1990. Only a small increase was observed for white females. In 1994, PML was reported in 2.1% of white males who died with HIV-associated disease compared with 1.2% of white females and 1.0% of black males and females who died of similar causes. The epidemic of PML deaths is increasing in parallel with the AIDS epidemic. The increase in HIV-associated PML deaths, first noted among males, has also become apparent among females and probably reflects the increasing importance of drug use and heterosexual transmission of HIV. The reason for the higher prevalence of PML among white males with HIV infection is unknown.

Discriminators between Hantavirus-Infected and -Uninfected Persons Enrolled in a Trial of Intravenous Ribavirin for Presumptive Hantavirus Pulmonary Syndrome

To provide a potentially therapeutic intervention and to collect clinical and laboratory data during an outbreak of hantavirus pulmonary syndrome (HPS), 140 patients from the United States with suspected HPS were enrolled for investigational intravenous ribavirin treatment. HPS was subsequently laboratory confirmed in 30 persons and not confirmed in 105 persons with adequate specimens. Patients with HPS were significantly more likely than were hantavirus-negative patients to report myalgias from onset of symptoms through hospitalization, nausea at outpatient presentation, and diarrhea and nausea at the time of hospitalization; they were significantly less likely to report respiratory symptoms early in the illness. The groups did not differ with regard to time from the onset of illness to the point at which they sought care; time from onset, hospitalization, or enrollment to death was significantly shorter for patients with HPS. At the time of hospitalization, patients with HPS more commonly had myelocytes, metamyelocytes, or promyelocytes on a peripheral blood smear, and significantly more of them had thrombocytopenia, hemoconcentration, and hypocapnia. Patterns of clinical symptoms, the pace of clinical evolution, and specific clinical laboratory parameters discriminated between these 2 groups.

Nosocomial exposure to parvovirus B19: low risk of transmission to healthcare workers.

OBJECTIVE To evaluate the risk of nosocomial transmission of parvovirus B19 (B19) infection to healthcare workers (HCWs) exposed to patients with transient aplastic crisis (TAC) caused by acute B19 infection. DESIGN Cohort study. SETTING 1,000-bed, urban teaching hospital in Atlanta, Georgia. PARTICIPANTS Eighty-seven exposed HCWs who cared for two patients with TAC prior to the time they were isolated and a comparison group of 88 unexposed HCWs from wards or clinics where the patients did not receive care. INTERVENTION Self-administered questionnaire on hospital contact with index patients, B19 community risk factors, and signs and symptoms suggestive of B19 disease. Serology for B19-specific IgM and IgG antibodies measured by antibody-capture enzyme-linked immunosorbent assay. RESULTS 1 (3.1%) of the 32 nonimmune exposed HCWs had serologic evidence of recent B19 infection compared to 3 (8.1%) of the 37 nonimmune HCWs in the comparison group (P = .6). In a subgroup analysis of exposed HCWs who cared for index patients during the time when the virus load was expected to be greatest, a recent infection rate of 5.8% (1/17) was found among nonimmune HCWs. CONCLUSIONS The finding of similar rates of recent infection in nonimmune exposed and unexposed HCWs suggests that transmission to HCWs did not occur, despite failure to place the patients in isolation at the onset of hospitalization.

Human Parvovirus B19 Antibodies in Infantile Autism

This case supports the hypothesis of Chugani et a1,12 that the pathophysiology of infantile spasms is an abnormal neuronal circuitry involving a functional interaction between an offending focal or diffuse cortical lesion and the brainstem raphe nuclei. Francesco Viani, MD Antonino Romeo, MD Massimo Mastrangelo, MD Hakam Asi, MD Epilepsy Center, Department of Pediatrics University of Milan Milan, Italy

Parvovirus B19 Quiescence during the Course of Human Immunodeficiency Virus Infection in Persons with Hemophilia

To detect and characterize parvovirus B19 infection during the course of progressive immune deficiency from human immunodeficiency virus (HIV), ten subjects enrolled in the Multicenter Hemophilia Cohort Study were followed for 6.4 to 15 years from HIV seroconversion through extreme immune deficiency. Four to five sera or plasma samples from each subject, collected at predetermined CD4+ lymphocyte levels, were tested for immunoglobulin G (IgG) and M (IgM) B19 antibodies and DNA. All 42 samples were positive for B19 IgG antibodies, and three were weakly positive for IgM antibodies. Only one sample, collected coincident with HIV seroconversion, was unequivocally positive for B19 DNA. No persistent hematologic adverse effects of B19 infection were observed. Thus, although B19 IgG antibodies are highly prevalent among HIV‐infected persons with hemophilia or related disorders, B19 viremia and its hematologic consequences were not detected, even with severe depletion of CD4+ lymphocytes. If primary B19 infection occurs after immune deficiency, however, the consequences may be more adverse. Am. J. Hematol. 56:248–251, 1997.