South Africa has been advised to pay attention to the human metapneumovirus (HMPV) outbreak in China but there is currently no cause for concern as it is one of the normal seasonal respiratory viruses.
University of Cape Town, Division of Medical Virology Associate Professor Marvin Hsiao said:“The outbreak had occurred likely because the lockdown during the Covid-19 pandemic had massively reduced the spread of HMPV in recent years. This in turn had resulted in many children who had not been previously exposed to the virus becoming infected in a short period.
“In South Africa, we did not have a prolonged lockdown compared to China and we had seen HMPV at a low but steady level in the past few years. So, the smaller group of susceptible children in South Africa means less likelihood of large outbreaks,” explained Hsiao.
Available information shows the outbreak is not due to a particularly dangerous strain of HMPV, said Hsiao.
He explained that HMPV is circulating in South Africa so returning travellers are not likely to cause problems as they did in the early Covid-19 era.
“All respiratory infections (Covid-19, influenza, human metapneumovirus) spread similarly so the usual protective measures (avoid close contact with sick individuals, maintain good ventilation, good hand hygiene etc.) would reduce the transmission of HMPV,” said Hsiao.
In an interview with eNCA on Monday, Stellenbosch University Centre for Epidemic Response and Innovation director, Professor Tulio de Oliveira, said ‘we don’t have anything to be concerned about, at the moment in South Africa’.
“We are not in our respiratory season at the moment. For example, in South Africa, we will suffer a wave of respiratory infection in the winter as most of the countries. So, we are in the summer months...,” explained De Oliveira.
The National Institute for Communicable Diseases (NICD) Respiratory Diseases and Meningitis head, Professor Cheryl Cohen, said HMPV already circulates every year (and year-round) in South Africa, as it is one of the normal seasonal respiratory viruses.
“The NICD has robust surveillance systems across South Africa which will be able to detect an increase in respiratory pathogen circulation and our laboratory has the capability to test for HMPV and other respiratory viruses. Many private laboratories in South Africa can also test for HMPV and other respiratory viruses,” explained Cohen.
What is HMPV?
Hsiao said HMPV is a virus that affects the human respiratory tract (airways). Even though it can infect people of all ages, it typically causes more severe illness in children, particularly those under the age of 5. HMPV infection tends to be associated with milder symptoms such as the common cold in older children or adults.
He explained that younger children are more likely to be infected because they lack immunity against HMPV. However, even for adults who had been infected before, the immunity is not complete and thus infection can still occur. In this repeat infection scenario, the disease is generally milder.
Additionally, Cohen said the virus is in the same family of viruses as the respiratory syncytial virus (RSV).
She said generally, younger children (infants less than 6 months of age, specifically those who are born prematurely), older people, people with comorbidities such as chronic lung and heart disease, those with conditions that affect the immune system (such as HIV) and people with diabetes are at increased risk of developing severe illness.
She said vaccines for HMPV are in the late stages of development.
“HMPV virus was first identified in 2001 but there is evidence that the virus circulated for decades before that. Circulation of HMPV does not have a defined season and in South Africa, the virus is detected all year round. HMPV causes respiratory illness as does SARS-CoV-2, but they are not closely related viruses,” explained Cohen.
How is HMPV spread?
“The virus is shed in respiratory secretions so can be transmitted directly through inhalation of tiny droplets generated by coughing, sneezing or talking. So close proximity to an infected person increases the risk of transmission. Alternatively, the infection can also be spread by hand through touching contaminated surfaces or objects,” explained Hsiao.
Like RSV and influenza, Cohen said HMPV is transmitted through respiratory droplets.
Symptoms of HMPV?
“On the mild spectrum, it most commonly causes a runny nose, sore throat, fever and cough. However, in some cases, complications such as shortness of breath, bronchitis, pneumonia, wheezing and exacerbation of prior asthma/chronic lung disease can occur,” said Hsiao.
Cohen added that HMPV is mostly associated with mild upper respiratory tract symptoms such as cough, sore throat, runny nose, headache and possibly a fever.
“In most cases, these symptoms resolve within a few days. In some cases, HMPV may also cause infection in the lower respiratory tract (bronchitis/bronchiolitis or pneumonia),” said Cohen.
How is HMPV tested?
Hsiao said to test for HMPV, a nasal or throat swab needs to be taken from a person suspected of HMPV infection. Then there are lab tests that can be done to detect HMPV.