Monkeypox is causing encephalitis in some patients 

Monkeypox is causing encephalitis in some patients 
© iStock/gorodenkoff

A new study by University College London (UCL) has found that monkeypox can sometimes cause neurological complications such as encephalitis, confusion or seizures. 

Monkeypox is a rare infection commonly found in west or central Africa. It is passed on from person to person through close contact with monkeypox blisters or scabs, touching clothing, bedding or towels by someone with monkeypox, or the coughs and sneezes of a person with monkeypox. 

Several studies have illuminated that muscle aches, fatigue, headache, anxiety and depression are common symptoms of monkeypox; however, UCL researchers have also found that encephalitis (brain inflammation), confusion or seizures could be additional possible symptoms. 

The findings were published in eClinicalMedicine. 

Studying data from previous outbreaks

The researchers carried out a systematic review and meta-analysis of evidence and found that 2-3% of patients had severe complications such as seizures or encephalitis, although those studies mainly involved hospitalised patients from previous years. The researchers note that there is still not enough evidence to estimate neurological complication prevalence in the current outbreak. 

To conduct their study, the researchers searched for studies that reported neurological or psychiatric symptoms of monkeypox that had been reported up until May 2022, before the global outbreak. 

Lead author Dr Jonathan Rogers (UCL Institute of Mental Health, UCL Psychiatry, and South London & Maudsley NHS Foundation Trust) said: “We found that severe neurological complications such as encephalitis and seizures, while rare, have been seen in enough monkeypox cases to warrant concern, so our study highlights a need for further investigation. 

“There is also evidence that mood disorders such as depression and anxiety are relatively common for people with monkeypox.” 

The UCL review collated 19 studies, with a total of 1,512 participants (1,031 of whom had a confirmed infection) in the US, Nigeria, Democratic Republic of Congo, Republic of Congo, and the UK.  

Discovering severe monkeypox complications

The researchers estimated that 2.7% of monkeypox patients experienced at least one seizure, 2.4% experienced confusion, and 2% had encephalitis, a brain inflammation that can cause long-term disability. However, there is very limited evidence for the occurrence of these symptoms – the review only identified two cases of seizures, five cases of encephalitis and six cases of confusion. Other preliminary evidence has reported more cases of these symptoms, which highlighted the need for larger studies to confirm the prevalence. Furthermore, the researchers said that further studies are needed to determine how monkeypox can impact the brain. 

The researchers were unable to pool data for psychosocial symptoms due to incomplete evidence. In some studies, they found half of the patients experienced at least one symptom of muscle aches, fatigue, headache, anxiety or depression. Moreover, monkeypox may also cause higher rates of mental ill health than other illnesses due to the sometimes disfiguring lesions and the stigma linked to how transmission is typically from close or sexual contact. 

The studies employed also did not have long enough follow-up with patients to know whether any symptoms lasted longer than the acute stage of the illness. The researchers also noted that participants were hospitalised, therefore, the neurological impact may not extend to mild monkeypox cases. 

Co-author Dr James Badenoch (Barts Health NHS Trust) said: “As there is still limited evidence into neurological and psychiatric symptoms in the current monkeypox outbreak, there is a need to set up coordinated surveillance for such symptoms. 

“We suggest that clinicians should be watchful of psychiatric symptoms such as depression and anxiety and ensure that patients have access to psychological and psychiatric care if needed.” 



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