Distributed via the CDC Health Alert Network
August 13, 2024, 2:30 PM ET
CDCHAN-00514
Introduction
The Centers for Disease Control and Prevention (CDC) has issued a Health Alert Network (HAN) Health Advisory to inform healthcare providers, public health authorities, and the general public about a significant increase in human parvovirus B19 activity in the United States. Parvovirus B19, a seasonal respiratory virus, is commonly transmitted through respiratory droplets by individuals who may either show symptoms or remain asymptomatic. The unusual surge in parvovirus B19 cases was first observed in 14 European countries during the first quarter of 2024. Although the United States does not conduct routine surveillance for parvovirus B19, recent reports indicate a worrying rise in its activity within the country.
This advisory aims to provide comprehensive information about the current situation, the nature of parvovirus B19, its transmission, symptoms, and recommended actions for healthcare providers, health departments, and the public. It is crucial that all stakeholders are aware of the risks and take appropriate measures to mitigate the spread of this virus.
Background
Understanding Parvovirus B19
Parvovirus B19 is highly contagious and primarily spreads through respiratory droplets. Household exposure can result in a 50% infection rate among susceptible individuals, while school outbreaks can infect 20-50% of students and staff. Historically, individuals working in educational settings and those in close contact with children, such as daycare workers and teachers, have faced a higher occupational risk of infection.
- Transmission: The virus can also be transmitted from mother to fetus during pregnancy and through the transfusion of blood components and certain plasma derivatives. The Food and Drug Administration (FDA) advises testing plasma-derived products and plasma units for parvovirus B19 using nucleic acid tests. However, whole blood is not screened for the virus in the United States.
- Symptoms: Many infected individuals are asymptomatic. Immunocompetent children and adults with symptoms usually experience a biphasic illness. The first phase, occurring about 7 days after infection, is marked by fever, myalgia, and malaise and lasts approximately 5 days. The second phase, occurring 7-10 days later, often includes a characteristic facial rash in children and joint pain in adults.
- Risk Groups: People without pre-existing immunity who are pregnant, immunocompromised, or have chronic hemolytic disorders are at higher risk of adverse health outcomes.
Recent Trends and Data
The CDC has received multiple reports indicating a spike in parvovirus B19 activity in the United States. This includes increased test positivity in clinical specimens and pooled plasma from large commercial laboratories. Notably, there is a rise in clusters of parvovirus B19-associated complications among pregnant individuals and those with sickle cell disease.
- IgM Antibodies: The proportion of people with IgM antibodies, an indicator of recent infection, has risen among all age groups from less than 3% during 2022-2024 to 10% in June 2024. The most significant increase was noted among children aged 5-9 years, from 15% during 2022-2024 to 40% in June 2024.
- Plasma Donors: Among plasma donors, the prevalence of pooled samples with parvovirus B19 DNA levels greater than 10^4 IU/mL surged from 1.5% in December 2023 to 19.9% in June 2024.
Transmission and Risk Factors
Methods of Transmission
Parvovirus B19 is primarily spread through respiratory droplets. However, it can also be transmitted through other means:
- Household Exposure: Around 50% of susceptible individuals get infected after close contact with an infected household member.
- School Outbreaks: School settings can see 20-50% infection rates among students and staff during outbreaks.
- Occupational Exposure: People working in close contact with children, such as teachers and daycare workers, face a higher risk.
Special Considerations for Pregnant Women
Parvovirus B19 infection during pregnancy can potentially lead to adverse outcomes:
- Fetal Risks: Although most fetal infections resolve spontaneously, there is a 5-10% risk of adverse outcomes like fetal anemia, non-immune hydrops, or fetal loss, particularly when infection occurs between gestational weeks 9-20.
- Management: Treatment for acute infection in pregnant individuals is primarily supportive, focusing on monitoring and treating severe fetal anemia.
Symptoms and Clinical Presentation
Biphasic Illness
Parvovirus B19 infection typically manifests in two phases:
- First Phase: This occurs approximately 7 days after infection and includes symptoms like fever, myalgia, and malaise. This phase lasts about 5 days and is when individuals are most contagious.
- Second Phase: Occurring 7-10 days later, this phase is marked by a characteristic facial rash in children (often described as a “slapped cheek” appearance) and joint pain in adults. A reticulated body rash may also appear.
Laboratory Findings
During the acute phase of illness, certain laboratory findings can aid in diagnosis:
- Reticulocyte Counts: A transient decrease in absolute reticulocyte counts lasting about 10 days.
- Anemia: Mild anemia may be observed.
- Thrombocytopenia and Leukopenia: These conditions may also be present.
Most individuals only require supportive care during the acute phase and will recover completely. Severe outcomes, such as myocarditis, hepatitis, or encephalitis, are rare, and there is no vaccine or specific treatment for parvovirus B19 infection.
Recommendations
For Healthcare Providers
Healthcare providers should be vigilant and consider parvovirus B19 as a potential diagnosis, particularly in patients presenting with typical symptoms or complications. Key recommendations include:
- Testing: Utilize nucleic acid amplification tests and serology to confirm diagnosis.
- Supportive Care: Most patients will require only supportive care. Monitor patients with severe symptoms or complications closely.
- Patient Education: Inform patients about the nature of the virus, its transmission, and preventive measures.
For Health Departments
Health departments should take proactive steps to monitor and control the spread of parvovirus B19:
- Surveillance: Implement surveillance systems to track parvovirus B19 activity and identify outbreaks promptly.
- Public Health Campaigns: Conduct awareness campaigns to educate the public about the virus and preventive measures.
- Resource Allocation: Ensure healthcare facilities have the necessary resources to manage and treat cases effectively.
For the Public
The general public can take several steps to reduce the risk of infection:
- Hygiene Practices: Maintain good hygiene, including regular handwashing and using tissues when coughing or sneezing.
- Avoid Close Contact: Limit close contact with infected individuals, especially in household and school settings.
- Seek Medical Advice: Pregnant women and individuals with chronic conditions should seek medical advice if they suspect exposure to parvovirus B19.
FAQs
What is parvovirus B19?
Parvovirus B19 is a highly contagious respiratory virus that spreads through respiratory droplets and can cause a range of symptoms, from mild fever to severe complications in certain risk groups.
How is parvovirus B19 transmitted?
The virus is primarily spread through respiratory droplets but can also be transmitted from mother to fetus during pregnancy and through blood transfusions.
What are the symptoms of parvovirus B19 infection?
Symptoms include a biphasic illness with fever, myalgia, and malaise in the first phase, followed by a characteristic facial rash in children and joint pain in adults during the second phase.
Who is at higher risk for severe outcomes?
Pregnant women, immunocompromised individuals, and those with chronic hemolytic disorders are at higher risk for severe outcomes from parvovirus B19 infection.
Is there a vaccine for parvovirus B19?
Currently, there is no vaccine or specific treatment for parvovirus B19 infection. Management is primarily supportive.
Conclusion
The recent increase in parvovirus B19 activity in the United States is a cause for concern, particularly for vulnerable populations such as pregnant women and individuals with chronic conditions. Awareness and proactive measures are essential to mitigate the spread of the virus and manage its impact. Healthcare providers, health departments, and the public must work together to address this emerging public health issue effectively. By following the recommended guidelines and maintaining good hygiene practices, we can reduce the risk of infection and protect the health and safety of our communities.