Human bocavirus (HBoV) is one of many types of viruses that cause the common cold, respiratory infections, and gastroenteritis in humans. There are four genotypes in the genus Bocavirus that medical researchers have identified in the past several years since discovery of this virus in human specimens: HBoV1, HBoV2, HBoV3, and HBoV4. The researchers first isolated HBoV1 from respiratory secretions; they found the other strains primarily in stool samples.
HBoV is a small single-stranded DNA virus in the Parvoviridae family of viruses. Health care professionals discovered HBoV in 2005 in nasal washing specimens from children with respiratory infection of unclear cause. About 3% of the specimens contained a bocavirus now called HBoV1. This discovery was made possible by new laboratory techniques, including PCR (polymerase chain reaction) testing to detect viral DNA.
Health care providers have found human bocavirus throughout the world, mostly in pediatric cases, but it is not clear how significant or common a role it plays in human disease. Physicians often find HBoV along with another respiratory virus in sick individuals, there are no known HBoV infections in animals that health researchers can study, and it is very difficult to grow HBoV in the laboratory. Like parvoviruses, young children may shed HBoV for several weeks. It may be an "innocent bystander" in many individuals, it may cause infections by itself, or it may add to or worsen other viral infections. Recent cases suggest that it is capable of causing disease on its own, most often in individuals with underlying lung abnormalities or weak immunity.
Most bocavirus infections are respiratory and associated with HBoV1. Symptomatic disease affects the very young, between ages 6 and 24 months. Bocaviruses can infect adults, but adults seem much less likely to have symptoms. Transmission probably occurs from respiratory secretions from a person's nose, throat, and mouth. Bocaviruses that cause gastrointestinal infection shed in stool but seem less common.
It is not clear what the incubation period for bocavirus infections may be. It may be shed for several weeks by asymptomatic children, and over 70% of HBoV respiratory infections involve another virus, as well. It is not possible as yet to pinpoint when a sick person became infected with HBoV, so it impossible to determine a typical time frame between infection and start of symptoms.
It is not clear what the contagious period for bocavirus infections may be, but healthy or sick people can shed bocavirus in respiratory secretions, off and on, for many weeks.
One study detected bocavirus in nasal swab samples of 20 out of 45 healthy asymptomatic children at one day care center, and the infected children shed the virus for a very long time. It's reasonable to assume that young children in group child care may develop an HBoV infection at some point. A study by the U.S. Centers for Disease Control and Prevention (CDC) of children from birth to age 13 monitored HBoV1 antibody levels and found that bocavirus infected all of the 109 healthy children by age 6, one as young as 3.7 months. Adults exposed to young children and child care situations are probably at risk for HBoV infection. Premature babies and children with lung problems may be at risk for more serious disease. People with weakened immune systems seem to be at risk for more symptomatic or severe infection. HBoV can cause serious or life-threatening infections on its own in people with weak immunity.
Human bocavirus infections have been associated with colds and upper respiratory infections, as well as gastroenteritis. Symptoms most often appear as a cold, with fever, runny nose, and cough. Diarrhea may occur with gastroenteritis.
Patients also reported wheezing and bronchiolitis, and this can progress to pneumonia (lower respiratory infection). Signs include shortness of breath (dyspnea), wheezing of the lungs on examination, blue lips (cyanosis), and low oxygen (hypoxia) in more serious disease. Medical professionals may see mild inflammation changes with bronchopneumonia on X-rays of the lungs.
Many other viruses may cause wheezing and bronchiolitis, and testing for even common respiratory viruses is not routinely available, so it is not clear how often bocaviruses may cause serious disease. Some cases of serious disease where testing for HBoV is available and performed are more likely to be reported in the medical literature. Many cases may go undetected at this time.
Health professionals diagnose HBoV by testing for it by PCR in nose or throat secretions, phlegm that is coughed up, or diarrhea specimens. Most often, health professionals do this only for research purposes.
PCR testing for respiratory viruses is not commonly available in health care clinics, nor even in many well-equipped hospitals. Many screening tests for respiratory virus PCR only test for common viruses like rhinovirus and influenza but do not yet include HBoV. Detecting respiratory viruses other than influenza does not typically change how these infections are treated. The tests are often extremely expensive, so health professionals may not order testing except in very serious cases in which the diagnosis is not clear.
The treatment for human bocavirus infections is supportive at this time. There is no antiviral treatment known to be helpful at this time. People may use over-the-counter medications to lower fever and relieve sore throat, such as acetaminophen (Tylenol). Doctors recommend drinking plenty of fluids, getting plenty of rest, and staying home away from others until the symptoms go away.
The only home remedies for bocavirus infections include over-the-counter and supportive therapy as mentioned above.
There is not enough research information on human bocavirus infections to determine how long these infections last. Symptoms may last about as long as a typical respiratory viral infection lasts, or about a week. The infection itself may for several weeks
The prognosis for most bocavirus infections is probably quite good for most individuals. Not enough is known about these viruses to determine who may have a worse prognosis than another individual. In general, people with weakened immunity or chronic lung problems are more likely to have complications from any respiratory virus, including HBoV. Reports of cases with severe or life-threatening infection that appears to be due to HBoV range from fair to poor.
It is probably difficult to prevent bocavirus infections in young children, especially if they are in group child care. General good hygiene helps limit HBoV and many other types of infections in babies, children, and caregivers, whether in day care, at school, or at home. Teaching children to sneeze and cough into their elbow or a disposable tissue is an excellent habit, as well as teaching them to use hand sanitizer frequently or wash hands with soap and water. Avoid sharing eating and drinking utensils in group settings. Keeping children or yourself at home and away from others when sick is also important.
There is no vaccine for bocavirus infections.
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