Sex ratio in outbreaks of parvovirus B19 infection

Infection Control Measures for Human Parvovirus Bl9 in the Hospital Setting

A human parvovirus was first discovered serendipitously in blood from asymptomatic donors in 1975' and designated B19 because of the location of the original positive serum in a test panel. Subsequently, the newly discovered virus was determined to be the etiologic agent of most cases of transient aplastic crisis in the setting of chronic hemolytic anemia and of the childhood exanthem erythema infectiosum, or fifth disease. While erythema infectiosum with its classic “slapped-cheek” rash is a childhood illness, “fifth disease” in the adult should not be overlooked. At least 40% of adults lack serological evidence of past human parvovirus B19 infection and are at risk. Adults tend to have a more subtle rash, often lacking the “slapped cheeks,” and tend to have a more severe constitutional, flu-like illness with prominent joint symptoms. While the arthralgia and arthritis of adult “fifth disease” are often self-limiting, they may become chronic and lead to an arthropathy that meets American College of Kheumatology criteria for a diagnosis of rheumatoid arthritis. The arthropathy has been reported to persist up to five years, the longest follow-up now available (A. Wolf; MD, personal communication, August 27, 1987).

Persistent adeno-associated virus 2 and parvovirus B19 sequences in post-mortem human cerebellum

We previously reported in a large cohort (N = 104) of post-mortem tissues the detection of both the non-pathogenic adeno-associated virus (AAV2) in approximately 13% and the pathogenic human parvovirus B19 (B19) in approximately 42% of human brains, particularly the dorsolateral prefrontal cortex. Multiple animal parvoviruses target the developing cerebellum (CBLM) resulting in hypoplasia and ataxia, but very little is known about the human parvoviruses and their ability to infect or cause disease in the CBLM. We have now confirmed in the above cohort the presence of AAV2 and B19 sequences in the CBLM. Our results show that approximately 27% and approximately 70% of human CBLM are positive by nested polymerase chain reaction for AAV2 and B19 sequences, respectively. We also document in a second cohort (N = 10) the presence of AAV2 (50%) and B19 (100%) sequences in the CBLM and correlate our results for B19 with studies from matched sera. Eighty percent (80%) of this cohort was positive for anti-B19 IgG, while none were IgM+, suggesting that most individuals had been previously infected with B19 but none acutely. To our knowledge, this study is the first to demonstrate that both AAV2 and B19 sequences are present at relatively high frequencies in the CBLM and are likely due to persistent rather than acute infection. Further studies will lead to insights into AAV2- and/or B19-CBLM interactions including mechanisms of infection, persistence, and possibly neuropathology, including cerebellar hypoplasia and ataxia.

Parvovirus B19 infection in medical students during a hospital outbreak

From March to May 2002, a parvovirus B19 (B19) outbreak was identified at a general hospital that serves as a teaching facility for the Universidad Autónoma de San Luis Potosí, Mexico. Medical students attending the hospital presented with symptoms suggestive of B19 infection. Previous studies have suggested that apparent hospital-related B19 outbreaks may be a reflection of B19 infection in the community. A study was undertaken to assess whether exposure to the hospital was a risk factor for B19 infection and to determine to what extent medical students were infected during this outbreak. The incidence of B19 infection in medical students attending the teaching hospital during the outbreak (n = 211) was determined and compared to students not attending the hospital (n = 96). To assess if a community-wide outbreak had occurred, 80 blood donors were also evaluated for the presence of B19 antibodies. Acute B19 infection was identified in 40 of 119 (33.6 %) susceptible students attending the hospital and in 20 of 47 (42.6 %) susceptible students not attending the hospital. The frequency of acute infection among susceptible blood donors was lower (9.5 %) than in students, but higher than the rate expected during non-epidemic periods. Most infections (68.3 %) were asymptomatic. Symptoms reported by infected subjects were not specific for B19 infection. Only 11.7 % of subjects with acute infection fulfilled the clinical surveillance definition used to detect cases during the outbreak. In conclusion, hospital exposure was not associated to increased risk of B19 infection among medical students. Medical students may be at increased risk for acquiring and transmitting B19 infection during outbreaks.

The 1994 human parvovirus B19 epidemic in Denmark: diagnostic and epidemiological experience

In 1994 the first human parvovirus B19 (B19) epidemic to be documented in Denmark was recorded from February 2 to September 30. In total, 10,333 serum samples were tested for specific B19 IgM and IgG antibodies, using IDEIA Parvovirus B19 IgM and IgG kits. The prevalence of B19 IgM positivity was 11% for the whole period and 29% at the peak of the epidemic in week 14, declining from week 39 and onwards to 1-3%. The prevalence of B19 IgG (IgM-negative samples) was 60%, indicating an earlier infection, and the same for men and women. The gender distribution of tested patients was the same at the beginning of the epidemic as at the end of the epidemic and a year after its peak, i.e. 86% of samples were from women and only 14% from men. Age distribution for women was the same for the three periods (median age 34 years). For men the median age was 32 years, 39 years and 31 years, respectively. Only a few samples from children were tested. No change in test pattern was observed during the three periods. Approximately 75% of all samples tested were from women of childbearing age (18-45 years old), suggesting a fear of fetal complications in an actual or future pregnancy, rather than a serological verification of clinical symptoms. From the sparse clinical information that accompanied the serum sample we were not able to demonstrate that women were more likely than men to have a symptomatic B19 infection. With reservations we estimate that 14% of adverse pregnancy outcome is correlated with a B19 infection.

The incidence of, and factors leading to, parvovirus B19-related hydrops fetalis following maternal infection; report of 10 cases and meta-analysis

OBJECTIVES

to clarify the approximation of the frequency of B19-related nonimmune hydrops fetalis (NIHF), and to know the critical period during which maternal infection led to NIHF.

METHODS

we investigated the characteristics of 10 cases of antenatal B19 infection diagnosed over the past 10 years in Miyagi prefecture, Japan, and performed a meta-analysis of these cases and those previously reported in the literature.

RESULTS

NIHF caused by intrauterine B19 infection was diagnosed between 11 and 23 weeks of gestation in 10 women over the past 10 years in Miyagi prefecture, Japan. The source of infection was the mother's older child in six out of 10 cases, and children at a kindergarten where the mothers worked in two cases. The interval between the onset of infection and the diagnosis of NIHF ranged from 2 to 6 weeks. B19 infection was responsible for 10 (15.2%) in 66 cases of aetiology unknown NIHF in this study, and for 57 (19.1%) of 299 cases of non-malformed or aetiology-unknown NIHF by meta-analysis of the literature. Meta-analysis of the 165 reported cases of antenatal B19 infection, including the 10 cases described above, showed that there was a 10.2% excess risk of fetal death in women infected with B19 during pregnancy and a 12.40% excess risk in women infected during the first 20 weeks of pregnancy. Transplacental transmission was confirmed in 69 (24.1%) of 286 cases. The mean gestational age at diagnosis of NIHF was 22.8 +/- 5.1 weeks. The mean interval between the onset of maternal infection and diagnosis of NIHF was 6.2 +/- 3.7 weeks.

CONCLUSIONS

these approximations will be useful for counselling and management for pregnant women. The critical period during which maternal infection led to NIHF correlated with the hepatic period of hematopoietic activity. These findings suggest that parvovirus B19 may have an affinity for erythroid lineage cells at the hepatic stage of hematopoiesis, which may strongly influence the clinical features of feto-maternal B19 infection.

Parvovirus B19 outbreak in a children's ward

Parvovirus B19 infection can cause severe complications in pregnant women, individuals with haemolytic anaemia, and those who are immunocompromised. In a hospital outbreak of this infection, a balance should be struck between protection of these individuals and the maintenance of medical services. The index case of an outbreak of parvovirus B19 infection among staff and patients of a paediatric ward was not identified. 58 members of staff were screened for B19 markers and 4 of the 6 susceptible men and 6 of the 24 susceptible women became infected (p = 0.05) as defined by serum IgM and viraemia. 1 of the 11 adults (10 members of staff and 1 parent) infected remained symptom-free. 12 immunocompromised patients were also assessed, and symptom-free infection developed in 2 of these. During the outbreak staff with symptoms were put on sick leave, immunocompromised patients (there were none with haemolytic anaemia) were given normal human immunoglobulin and nursed in single rooms by B19 IgG-positive, IgM-negative staff, and the ward was closed to B19 IgG-negative pregnant women. However, the limitation of spread of infection cannot be attributed with certainty to the measures taken.

Human parvovirus B19 infection among hospital staff members after contact with infected patients

In the spring and summer of 1988, two separate outbreaks of an illness with a rash resembling erythema infectiosum occurred among members of the nursing staff of the Children's Hospital of Philadelphia. The sources were two adolescent patients with sickle cell disease and aplastic crisis who had unsuspected parvovirus infection. Tests for IgM and IgG antibodies to parvovirus B19 were positive in both patients, and electron microscopical examination showed parvovirus-like particles in the early serum samples. Of 40 health care workers exposed to infected patients, 12 (30 percent) were infected, 2 (5 percent) were possibly infected, 8 (20 percent) had evidence of a past infection with B19, and 18 (45 percent) remained seronegative. Attack rates among the susceptible contacts were 36 percent in the first outbreak and at least 38 percent in the second. Clinical symptoms began a mean of 12.6 days after exposure and included malaise, rash, and joint pain. We conclude that hospital workers are at risk of contracting nosocomial erythema infectiosum from patients with parvovirus-associated aplastic crisis. We recommend that all patients with hereditary hemolytic anemias who are admitted with a febrile illness be evaluated for aplasia and promptly placed in respiratory and contact isolation if aplastic crisis is suspected.

Infection control measures for human parvovirus B19 in the hospital setting

A human parvovirus was first discovered serendipitously in blood from asymptomatic donors in 1975' and designated B19 because of the location of the original positive serum in a test panel. Subsequently, the newly discovered virus was determined to be the etiologic agent of most cases of transient aplastic crisis in the setting of chronic hemolytic anemia and of the childhood exanthem erythema infectiosum, or fifth disease. While erythema infectiosum with its classic “slapped-cheek” rash is a childhood illness, “fifth disease” in the adult should not be overlooked. At least 40% of adults lack serological evidence of past human parvovirus B19 infection and are at risk. Adults tend to have a more subtle rash, often lacking the “slapped cheeks,” and tend to have a more severe constitutional, flu-like illness with prominent joint symptoms. While the arthralgia and arthritis of adult “fifth disease” are often self-limiting, they may become chronic and lead to an arthropathy that meets American College of Kheumatology criteria for a diagnosis of rheumatoid arthritis. The arthropathy has been reported to persist up to five years, the longest follow-up now available (A. Wolf; MD, personal communication, August 27, 1987).