G. William Gary

Management and outcomes of pregnancies complicated by human B19 parvovirus infection: A prospective study

During a large statewide outbreak of fifth disease in Connecticut in 1988, 39 pregnant women were identified who had serologic evidence of recent human B19 parvovirus infection. The patients were followed up prospectively with targeted fetal ultrasonographic examinations to detect signs of fetal hydrops. Of these 39 pregnant women, 37 had healthy infants and two patients had miscarriages. None of the fetuses developed hydrops. We propose that pregnant women exposed to B19 parvovirus be tested for evidence of IgG and IgM B19-specific antibodies and that targeted fetal ultrasonography be considered when IgM antibodies are found. Percutaneous umbilical blood sampling and intrauterine transfusion can be considered in cases of B19 parvovirus-associated hydrops and anemia. The overall fetal loss rate in this prospective follow-up group was 5%.

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.

Diarrheal illness among infants and toddlers in day care centers. II. Comparison with day care homes and households

During the second year of a prospective study of diarrheal illness among 0- to 36-month-old children in day care centers in Maricopa County, Arizona, we concurrently studied children of the same age in 30 day care homes and 102 households not using day care. The seasonal pattern of diarrhea, frequency of pathogen isolation, and relative frequency of individual pathogens were similar in the three settings. Giardia lamblia and rotavirus were the most common enteropathogens. Asymptomatic infection was identified in 14% to 21% of infant-toddler contacts of pathogen-positive cases of diarrhea. We compared rates of diarrhea in the three settings using five serial biweekly family-based surveys during the period of highest diarrhea rates. The incidence in infants and toddlers in DCCs (42 cases per 100 child months) was significantly higher than in DCHs (23 cases per 100 child-months) and in households not using day care (27 cases per 100 child-months); the DCH rate did not differ significantly from that in households not using day care. Among household sample children who began using day care during the survey period, the incidence of diarrhea was significantly higher than in household sample children not using day care.

Diarrheal illness among infants and toddlers in day care centers. I. Epidemiology and pathogens

We conducted a 2-year prospective study of diarrheal illness in children ages 0 to 36 months in 22 day care centers in Maricopa County, Arizona. In 7464 child-months of observation, 465 sporadic cases and 170 outbreak-associated cases of diarrhea were identified. Enteric pathogens were identified in 20% of diarrhea episodes. Giardia lamblia, rotavirus, and Campylobacter jejuni were the most common pathogens. Giardia was significantly more common in toddlers than in infants and was found in 19% of asymptomatic child contacts of symptomatic infected children. Rotavirus was significantly more common in infants than in toddlers. In outbreaks, shorter duration of child enrollment was associated with illness. Comparison of day care center characteristics revealed that only a lower score in standardized observations of hygiene and child-handling practices was associated with greater risk of diarrhea. Infectious diarrhea appears to be common in diaper-age children in day care centers, but the patterns of disease differ for different pathogens and for the infant and toddler age groups.

A WATERBORNE OUTBREAK OF GASTROENTERITIS WITH SECONDARY PERSON-TO-PERSON SPREAD: Association with a Viral Agent

In December, 1976, an outbreak of gastroenteritis occurred at a resort camp in Colorado. Data obtained by questionnaire from 760 persons indicated that 418 (55%) had had gastroenteritis at the camp or within a week of leaving it, with peak onset within a two-day period. Symptoms included vomiting (81%), diarrhoea (65%), and fever (49%); median duration of illness was twenty-four hours. The attack-rate increased with consumption of water or ice-containing beverages. The camp water supply was found to be inadequately chlorinated and contaminated by a leaking septic tank. Although routine laboratory tests did not reveal bacterial, viral, or parasitic pathogens, immune electron microscopy detected virus-like particles in two of five diarrhoeal stool filtrates. Oral administration of one of these bacteria-free filtrates to two volunteers induced a gastrointestinal illness similar to that observed in the camp visitors.

Severe Anemia Caused by Human Parvovirus in a Leukemia Patient on Maintenance Chemotherapy

A 6-year-old boy on maintenance chemotherapy for acute lymphocytic leukemia developed severe hypoplastic anemia during chemotherapy previously well tolerated. The hypoplastic episode persisted for approximately 30 days. Human parvovirus (B19), the etiologic agent of aplastic crisis in persons with underlying hemolytic syndromes, was detected in the patients serum 25-30 days after onset of hemoglobin decrease, and B19 IgM seroconversion occurred 1 week later. The patients hypoplastic anemia was presumably caused by prolonged B19 infection resulting from a blunted immune response. An immune response to the B19 infection and resolution of the illness were temporally associated with brief cessation of chemotherapy.

Characterization of Nodamura virus, an arthropod transmissible picornavirus

Abstract Nodamura virus, an arthropod-transmissible virus which is resistant to ether and chloroform, was characterized by electron microscopic, physical, and additional immunological studies. Examination of thin sections of limb muscles of infected infant mice revealed extremely large numbers of virus particles (28 nm in diameter) dispersed and in crystalline array within sarcoplasm. Two kinds of viroplasmic inclusions and severe destruction of skeletal muscle cell architecture were associated with the presence of virus. Kupffer cells in the liver of these animals also contained large aggregates of virus particles. Negative contrast preparations contained virus particles 29 nm in diameter with cubic symmetry. The virus was morphologically indistinguishable from picornaviruses. The density of infectious virus was 1.34 g/ml; it was insensitive to pH 3.7, and its sensitivity to heat (50 °) was not stabilized by molar MgCl 2 . Since serum neutralization tests against 10 swine enteroviruses were negative, as were previously reported attempts at serological identification, Nodamura virus remains a picornavirus unrelated to any known virus, but with a demonstrated capacity for transmission by and multiplication in arthropods.

Colorado tick fever virus: An electron microscopic study

Abstract Colorado tick fever (CTF) virus was observed by ultrathin section and negative contrast electron microscopy. In sections of infected cultured cells and of mouse brain, virus particles (75 mμ in diameter) with electron dense cores were associated with intracytoplasmic granular matrices, arrays of intracytoplasmic filaments, and fine kinky threads. Occasionally, virus particles were enveloped by membranes of cytoplasmic organelles. Intranuclear filaments in dense arrays were frequently found in infected cells. In negative contrast preparations the virus was round, 80 mμ in diameter, with regularly spaced surface projections suggestive of cubic symmetry. Partial removal of surface components permitted the observation of an inner capsid 50 mμ in diameter. CTF virus was directly compared with reoviruses, which in several ultrastructural characteristics it resembles.

Waterborne Gastroenteritis due to the Norwalk Agent: Clinical and Epidemiologic Investigation

An outbreak of gastroenteritis occurred at a Pennsylvania summer camp in July 1978. Symptoms included abdominal pain (81 per cent), nausea (72 per cent), and vomiting (53 per cent); upper respiratory infection symptoms occurred in 35 per cent of the campers. Illness was associated with consumption of five or more glasses of water or water-containing beverages. Stool cultures from affected persons were negative for bacterial pathogens; however, a fourfold or greater rise to the Norwalk agent was demonstrated in serum samples of three of three ill persons tested and in none of eight controls (p < .02). Campers ill during the first session who were also present during the second session did not become ill during the second session (p < .001). (Am J Public Health 1982; 72:72-74.)

The ultrastructure of disrupted herpesvirus nucleocapsids

Abstract Nucleocapsids prepared by treating herpes simplex or varicella-zoster virions with Nonidet P-40 were found to be degraded by EDTA-trypsin. Initial action of the enzyme appeared to be to degrade the pentameric capsomeres located on the vertices of the icosahedron and thus cause the capsid to flatten and the capsomeres to align in a characteristic radial array. Examination of hexagonal clusterings of capsomeres showed that they were linked by strands approximately 2 nm wide which originated from edges of the hexagonal prisms. A tri-membered arrangement for these intercapsomeric linkages was proposed in which one strand linked adjacent capsomeres and the central capsomere of the cluster.