Viruses – parvovirus

What are the key principles of preventing viruses – parvovirus?

The key principles of preventing parvovirus B19 (B19) infections include:

• The virus is relatively resistant to heat and chemical inactivation.

• Transmission of the virus occurs primarily via contact with respiratory droplets so droplet precautions are indicated in addition to contact precautions.

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• Viral infection manifests in a variety of different clinical presentations, three of which (transient aplastic crisis, papular-purpuric “gloves and sock syndrome”, and chronic anemia in immunocompromised patients) are infectious at the time of presentation and should be placed on isolation precautions upon admission.

• Isolation is maintained for the duration of hospitalization for immunocompromised patients with proven B19 infection as they can excrete the virus for prolonged periods. For patients with transient aplastic crisis (e.g., sickle cell anemia), precautions are continued for 7 days.

The human parvovirus B19 is a small, non-enveloped, single-stranded DNA virus with an icosahedral-shaped protein capsid. Its protein capsid and absence of an envelope make it relatively resistant to heat and solvents, features that likely contribute to its transmission.

Transmission occurs primarily via contact with respiratory droplets. This was clinically suspected and later confirmed by experimental infection of human volunteers: intranasal inoculation with virus led to clinical infection with excretion of virus in respiratory secretions that correlated with viremia. Fomite transmission is also highly suspected but has never been documented. The infection can also be transmitted in transfused blood products, especially pooled clotting factors.

Clinical infections with B19 manifest as different clinical syndromes depending on the immune status of the host. The degree and timing of infectivity varies among the different clinical manifestations. The most common clinical manifestation is erythema infectiosum (EI); also known as “fifth disease”, a benign generalized rash illness of childhood.

Patients with EI are only viremic for a brief time during a mild prodromal phase of illness before developing the characteristic rash; the rash occurs after the viremia resolves, coincident with the production of specific antibodies. These patients are not considered infectious after the rash appears. This pattern of infectivity occurring and resolving prior to the clinical manifestations of infection is also true for the polyarthropathy syndrome that can be seen in immunologically normal adults.

The “papular-purpuric gloves and socks” syndrome (PPGSS) is another exanthematous illness that can be seen in normal adolescents and adults, characterized by a petechial/purpuric rash in a distinct acral distribution. These patients are often viremic at the onset of this rash and so are also considered infectious when they present.

In patients with conditions of accelerated hematopoiesis, B19 can cause transient arrest of red cell production or so-called “transient aplastic crisis” (TAC). This is most commonly seen in patients with sickle hemoglobinopathies but has been described in many other hemolytic conditions.

B19 infections in other immunocompromised patients can lead to chronic infections manifesting as chronic anemia or frank red cell aplasia. This includes patients with congenital immunodeficiency states, chemotherapy-induced immunosuppression, and transplant patients, etc.

In contrast to patients with EI, patients with TAC or chronic red cell aplasia are usually viremic and infectious when they present with symptoms. Patients with TAC are considered infectious for a week after their presentation while immunocompromised patients with chronic anemia can have a more prolonged period of viral shedding and are considered infectious for a longer period.

What are the key conclusions for available clinical trials and meta-analyses that inform control of viruses – parvovirus?

No clinical trials or meta-analyses have been conducted to evaluate the impact of isolation measures on the prevention of nosocomial B19 infections.

What are the consequences of ignoring key concepts related to control of viruses – parvovirus?

Failure to recognize potentially infectious syndromes associated with parvovirus B19 infections and lack of isolation precautions can lead to a risk of transmission of the infection to health care personnel and to other patients. Both of these circumstances have been reported.

While the majority of B19 infections in immunocompetent adults are self-limited and uncomplicated, certain groups are at risk for more serious complications of infection. Primary infection in a pregnant woman can lead to intrauterine infection and risk of fetal death. Infection of a health care worker who is on immunosuppressive medication or has an unrecognized immunocompromising condition could lead to a chronic and possible severe B19 infection such as red cell aplasia or aplastic crisis.

What other information supports the key conclusions of studies of viruses – parvovirus e.g., case-control studies and case series?

Transmission from an infected patient to health care workers has been documented and reported, both as individual cases and as larger outbreaks among several health care providers. Secondary transmission from one health care worker to others has been reported (see references).

Summary of current controversies.

The risk to a female health care worker of child-bearing age caring for patients with suspected parvovirus B19 infection has been a controversial issue in the past. The potential consequences of a female of child-bearing age acquiring a primary B19 infection include not only the risk of illness in the female health care worker and possible transmission to patients, but also the additional risk of intrauterine transmission to the fetus.

This issue has been largely settled now as it is generally thought that the risk of acquiring a B19 infection while working in a hospital setting is no greater than the risk of acquiring the infection from other community sources. Several studies, including studies of community outbreaks and a prospective epidemiologic study, have identified contact with elementary school-aged children, either at home or at work, as the most important risk factor for the acquisition of B19 infection.

The risk to a woman of developing a B19 infection is increased if she has young, school-aged children at home or works with such children. In a large, prospective study, elementary school teachers and day care workers had higher annual rates of B19 seroconversion than nurses during non-epidemic periods, with elementary school teachers having the highest rate.

The risk to the health care worker can be further reduced if the immune status is known – those who are B19 IgG positive are immune. Adherence to hospital isolation policies likely provides further risk reduction though this has not been formally tested.

Overview of important clinical trials, meta-analyses, case control studies, case series, and individual case reports related to infection control and viruses – parvovirus.

There have been no clinical trials or meta-analyses. There are several case series and reports describing B19 infection in health care settings and at least one case-control study.

What national and international guidelines exist related to viruses – parvovirus?

Current recommendations of the Healthcare Infection Control Practices Advisory Committee (HICPAC) were published in the 2007 Guideline for Isolation Precautions:

Droplet precautions are recommended. “Maintain precautions for the duration of hospitalization when chronic disease occurs in an immunocompromised patient. For patients with transient aplastic crisis or red-cell crisis, maintain precautions for 7 days. The duration of precautions for immunosuppressed patients with persistently positive PCR [is] not defined, but transmission has occurred.”

The Communicable Diseases Surveillance Centre in London published “Guidance for the control of parvovirus B19 infection in healthcare settings and the community” in the Journal of Public Health Medicine in 1999.

What other consensus group statements exist and what do key leaders advise?

The 2012 Report of the Committee on Infectious Diseases, published by the American Academy of Pediatrics, makes a recommendation for isolation of the hospitalized patient with B19 infection to include droplet precautions. They further recommend informing any pregnant health care professionals of any potential risks to the fetus from parvovirus B19 infections and about preventive measures that may decrease the risk.

References

Siegel, JD, Rhinehart, E, Jackson, M. “Chiarello L, and the Hospital Infection Control Practices Advisory Committee. 2007 Guidelines for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings”. HICPAC. 2007. pp. 107

Pickering, LC, Baker, CJ, Kimberlin, DW, Long, SS. “American Academy of Pediatrics. Parvovirus B19 (Erythema Infectiosum, Fifth Disease)”. . 2012. pp. 539-41.

Crowcroft, NS, Roth, CE, Cohen, BJ, Miller, E. “Guidance for control of parvovirus B19 infection in healthcare settings and the community”. J Public Health Med. vol. 21. 1999. pp. 439-46.

Chen, YC, Chen, MY, Lu, CY. “Cluster of parvovirus infection among hospital staff working in coronary care units”. J Formos Med Assoc. vol. 109. 2010. pp. 886-94.

Lui, SL, Luk, WK, Cheung, CY. “Nosocomial outbreak of parvovirus B19 infection in a renal transplant unit”. Transplantation. vol. 71. 2001. pp. 59-64.

Miyamoto, K, Ogami, M, Takahashi, Y. “Outbreak of human parvovirus B19 in hospital workers”. J Hosp Infect. vol. 45. 2000. pp. 238-41.

Ray, SM, Erdman, DD, Bershling, JD. “Nosocomial exposure to parvovirus B19: low risk of transmission to healthcare workers”. Infect Control Hosp Edidemiol. vol. 18. 1997. pp. 109-14.

Dowell, SF, Torok, TJ, Thorp, JA. “Parvovirus B19 infection in hospital workers: community or hospital acquisition?”. J Infect Dis. vol. 172. 1995. pp. 1076-9.

Sneg, C, Watkins, P, Morse, D. “Parvovirus B19 outbreak on an adult ward”. Epidemiol Infect. vol. 113. 1994. pp. 345-53.

Adler, SP, Manganello, AMA, Koch, WC. “Risk of human parvovirus B19 infections among school and hospital emplyees during endemic periods”. J Infect Dis. vol. 168. 1993. pp. 361-68.

Koziol, DE, Kurtzman, G, Ayub, J. “Nosocomial human parvovirus B19 infection: lack of transmission from a chronically infected patient to hospital staff”. Infect Control Hosp Epidemiol. vol. 13. 1992. pp. 343-8.

Pillay, D, Patou, G, Hurt, S. “Parvovirus outbreak in a children's ward”. Lancet. vol. 339. 1992. pp. 107-9.

Bell, LM, Naides, SJ, Stoffman, P. “Human Parvovirus B19 infection among hospital staff members after contact with infected patients”. N Engl J Med. vol. 321. 1989. pp. 485-91.

Gillespie, SM, Cartter, ML, Asch, S. “Occupational risk of human parvovirus B19 infection for school and day-care personnel during an outbreak of erythema infectiosum”. JAMA. vol. 263. 1990. pp. 2061

Heegaard, ED, Brown, KE. “Human Parvovirus B19”. Clin Microbial Rev. vol. 15. 2002. pp. 485-505.

Anderson, MJ, Higgins, PG, Davis, LR. “Experimental parvovirus infection in man”. J Infect Dis. vol. 152. 1985. pp. 257-65.

Cherry, JD, Schulte, DJ, Feign, RD, Cherry, JD, Demmler-Harrison, GJ, Kaplan, SL. “Human Parvovirus B19”. . 2009. pp. 1902-20.

Harger, JH, Adler, SP, Koch, WC, Harger, GF. “Prospective evaluation of 618 pregnant women exposed to parvovirus B19: risks and symptoms”. Obstet Gynecol. vol. 91. 1998. pp. 413-20.

Kho, KA, Eisinger, K, Chen, KT. “Management of an obstetric healthcare provider with acute parvovirus B19 infection”. AM J Obstet Gynecol. vol. 198. 2008. pp. e33-4.

Adler, SP, Koch, WC, Remington, JS, Klein, JO, Wilson, CB, Baker, CJ. “Human Parvovirus”. . 2011. pp. 834-60.

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