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Dr Catherine Conlon Respiratory illness clusters in China - what is it and what are the risks?

The public health doctor looks at the concerns over an increase in respiratory illness in children in northern China.

SINCE MID-OCTOBER THE World Health Organization (WHO) has been monitoring reports of an increase in respiratory illness in children in northern China.

In mid-November, China’s National Health Commission reported a nationwide increase in the incidence of respiratory diseases predominantly affecting young children. Health authorities attributed this increase to the lifting of Covid-19 restrictions, the arrival of the cold season and circulating known pathogens such as respiratory syncytial virus (RSV), SARS-CoV-2, influenza and mycoplasma pneumonia. Both RSV and mycoplasma pneumonia are more common in children.

On 22 November, following reports of clusters of undiagnosed pneumonia in children’s hospitals in Beijing, Liaoning and other places in China, the WHO made an official request to China to provide additional information including laboratory results from these reported cases and data about recent trends in circulating respiratory pathogens. WHO was keen to know if the ‘clusters of undiagnosed pneumonia’ were separate events or part of the known general increase reported in the community.

The following day on 23 November, WHO held a teleconference with Chinese health authorities from the Centre for Disease Control (CDC) in China and the Beijing Children’s Hospital.

Increase in cases

The data provided indicated an increase in outpatient consultations and hospital admissions of children due to mycoplasma pneumonia since May and RSV, adenovirus and influenza virus since October. The WHO report that some of these increases are earlier in the season than normal but not unexpected given the lifting of Covid-19 restrictions, as has similarly occurred in other countries.

Chinese authorities reported no unusual disease presentation and no detection of any unusual or novel pathogens including in Beijing and Liaoning and the rise in respiratory illness had not exceeded hospital capacities. Surveillance for respiratory illness has increased in both inpatient and outpatient settings since mid-October.

This covers a broad spectrum of viruses and bacteria including for the first time mycoplasma pneumonia and the suggestion is that this may have contributed to increased detection and reporting of respiratory illness in children.

WHO says it is monitoring the situation closely and recommends that based on the available information the usual measures to reduce the risk of respiratory illness should be taken. This includes vaccination against influenza and Covid-19, staying at home when ill, getting appropriate medical attention, ensuring good ventilation, appropriate mask-wearing and hand hygiene. There are no recommendations for travel or trade restrictions based on the current information, nor specific measures for travellers to China advised.

What is causing this?

Mycoplasma pneumonia are bacteria that cause illness by damaging the lining of the respiratory system (throat, lungs, windpipe). Infection is spread by coughing or sneezing causing the release of small respiratory droplets containing the bacteria that can infect other people if they breathe in those droplets. People who spend a lot of time together are most at risk of infection.

Outbreaks of mycoplasma pneumonia mostly occur in crowded settings such as schools, college residential settings, long-term care facilities and hospitals.

Symptoms are generally mild including sore throat, tiredness, fever, slowly worsening cough that lasts for weeks or months or headache. Children under the age of five can present with sneezing, stuffy or runny nose, sore throat, watery eyes, vomiting or diarrhoea.

Pneumonia can occur presenting with fever and chills, cough, tiredness or shortness of breath. Once someone is infected with mycoplasma pneumonia, symptoms may take one to four weeks to occur.

Most people recover from infection without antibiotics. More severe infections may require antibiotics and there are several types to treat pneumonia caused by mycoplasma pneumonia.

While the infection is usually mild, complications can occur including serious pneumonia, asthma attacks, encephalitis (swelling of the brain), haemolytic anaemia (too few red blood cells which means fewer cells to deliver oxygen in the body), kidney problems or skin disorders. People at increased risk for serious infections include those recovering from a respiratory illness or those with a weakened immune system.

 

Could this happen here?

The Health Protection Surveillance Centre (HPSC) has said that an outbreak of mycoplasma pneumonia was notified to the HPSC in October and was the first in ‘a number of years.’ The situation is being monitored. Flu and Covid-19 levels remain relatively low at present while RSV cases are high with almost 300 patients hospitalised with RSV earlier this month: almost all infants and very young children.

Single cases of mycoplasma pneumonia are not notifiable in Ireland or in most European countries but outbreaks (more than one case that are epidemiologically linked) are notifiable.

Such a community outbreak was notified in October for the first time in a number of years. Otherwise, there is a small increase in detections this year by GPs with six cases notified in October and nine in November. In total, 19 cases have been reported in the community this year, compared to one case in 2022. The HPSC confirm that ‘these are just small numbers.’

Hospital detections also remain low with 13 cases this year compared to 77 in 2022. Cases of mycoplasma pneumonia are more common in summer and early autumn and peak cyclically every three to seven years.

‘Currently, the numbers of community mycoplasma pneumonia cases identified by the National Viral Reference Laboratory are higher than those seen last year but as infection follows a cyclical pattern, it is to be expected,’ the HPSC told the Irish Times, adding that they will continue to monitor infection trends.

The European Centre for Disease Control (ECDC) confirmed last week that an increase in respiratory infections in children is not unexpected in winter months in temperate regions of the world due to seasonal pathogens such as RSV, influenza, SARS-CoV-2 and mycoplasma pneumonia. EU/EEA countries and the UK are currently reporting increases in respiratory infections in children.

New strains

The concern over these cases is that the emergence of new flu strains or other viruses capable of triggering pandemics typically starts with undiagnosed clusters of respiratory illness with both SARS and Covid-19 first reported as unusual types of pneumonia.

However, the Chinese health ministry has concluded that the surge in respiratory illnesses across China is caused by flu and other known pathogens and not by a novel virus.

A local media outlet, Sixth Tone stated recently that the number of infected children in several provinces appears to have fallen. The Deputy Director of China’s Centre for Disease Control and Prevention, Professor Quanyi Wang reported on 20 November that mycoplasma pneumonia was no longer among the top three respiratory infections among children in Beijing.

‘The three years of zero-Covid restrictions may have lowered people’s normal levels of immunity to influenza-like viruses which could lead to a wave of infections in winter months,’ Prof Wang said.

Epidemiologist and medical statistician at Hong Kong University, Professor Ben Cowling agrees.

‘It’s just a relatively large seasonal surge, perhaps partly due to chance and partly because there’s a bit of ‘immunity debt’ from the lesser winter surges in the last three years,’

For now, the WHO and European and national health authorities agree – watch this space.

Dr Catherine Conlon is a public health doctor in Cork and former director of human health and nutrition, safefood.

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Dr Catherine Conlon
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