Man who caught virus from a monkey in a critical condition – B virus explained

A 37-year-old man wounded by a wild monkey in Hong Kong is in intensive care suffering from infection with B virus.

Although this is the first reported case of a B virus infection in a human in Hong Kong, it is not the first in the world. The US Centers for Disease Control and Prevention has recorded 50 cases of human infection since 1932, when the virus was first identified. Twenty-one of those infected died.

The first person – as far as we know – to catch B virus was a young doctor called William Brebner. He was bitten by a macaque monkey while researching poliovirus. The bite wound healed, but neurological illness eventually ensued, leading to respiratory failure. Brebner died at Bellevue Hospital, New York, in November 1932.

After his death, his brain tissues were found to cause neurological damage when injected into rabbits. Brebner’s colleagues Albert Sabin and Arthur Wright labelled this agent “B”.

We now know that the virus belongs to the herpes family, hence its other moniker: “herpes virus B”. It is a biosafety category 4 virus, the highest level – the same as Ebola and unknown new pathogens.

Prompt treatment with antiviral drugs can be lifesaving, but B virus remains a deadly pathogen. If not treated promptly, it has a mortality rate of 70%. There is no vaccine against this virus.

Most cases of B virus infection have involved laboratory workers handling captive animals or monkey tissues, rather than those living alongside these excitable, toothy animals in the wild.

Old World primates

In this most recent case, the 37-year-old man was attacked by macaques at Hong Kong’s Kam Shan Country Park – known locally as Monkey Hill. There are about 1,800 wild monkeys in Hong Kong, including two different macaque species. The authorities are warning people not to approach these creatures.

Macaques are a particularly adaptable group of old world primates with a wide global distribution. They live in towns, villages and temples across Asia and have been introduced elsewhere. They include the Barbary apes of Gibraltar, which were provided with rations by the British army after the second world war.

Macaques can harbour B virus, without symptoms.
Panther Media GmbH / Alamy Stock Photo

They are eaten as a delicacy in Indonesia and sold elsewhere as bush meat. Indonesian folklore through the centuries provides detailed observations of these creatures, but reassuringly no evidence that macaques caused harm to humans.

Despite lots of contact with many humans, there are remarkably few recorded episodes of spill-over of B virus outside laboratories. The virus does not spread easily.

A few cases show that bites and scratches from a macaque, or contact with the monkey’s mouth, nose or body fluids can transfer B virus that may be on the animal’s skin or in its mouth. (Most macaque populations harbour B virus, but without symptoms.)

Signs of infection in a human usually develop within two to 30 days. There may be blisters around the contact point or wound, together with a flu-like illness.

The virus can spread to lymph nodes and the nervous system. This causes agitation, confusion, double vision, trouble with coordination and muscle weakness.

Patients can develop hiccups if this inflammation involves the brain stem. If it reaches the lungs, they may need to be admitted to an intensive care unit.

No immediate fear

Spread of this virus between humans is highly unlikely. Only one account describes the spread of B virus from one human to another. The contact case was linked to the use of a cream previously used on a patient.

There is no evidence of a new B virus strain in the primates on Monkey Hill, so this case of herpes B has no features of a new zoonosis. However, it should raise our awareness of the potential risks posed by viruses carried by animals. Läs mer…

Strep A: cases of rare fatal infection hit record levels in Japan – here’s what risk these bacteria pose to global health

There has been a sharp increase in the number of people in Japan suffering with the rare but dangerous bacterial condition, streptococcal toxic shock syndrome (STSS). According to reports, cases of this potentially fatal strep A illness have more than tripled in Tokyo compared with this time last year.

While experts aren’t entirely certain why cases have risen so sharply to record levels, many believe it could be due to people being less vigilant about protecting themselves from infection after COVID measures were dropped.

Many countries, including the UK, have seen a similar increase in illnesses caused by strep A bacteria in the post-lockdown period – highlighting the continued burden that these bacteria have on public health.

Group A strep

STSS is caused by group A streptococcal bacteria, whch are quite common. Between 5% and 20% of healthy adults have these bacteria living inside them without any symptoms. But even when they don’t cause illness, group A streptococcal bacteria can still be spread to other people unknowingly through touch, coughs and sneezes.

Strep A bacteria are commonly spread through close contact with an infected person. This means that people who spend time in crowded places – such as schools or dormitories – may be at greater risk of catching these bacteria. Even people who aren’t ill can be colonised by them, as they are well adapted to grow in healthy human hosts.

But strep A bacteria can shift gears from being symptom-free and harmless into the source of numerous diseases. Infection may be triggered by larger numbers of the bacteria, mutation to a more aggressive strain, or perhaps some reduction in host defences. Most often, this will cause localised, short-lived infections – such as strep throat, tonsillitis or impetigo on the skin.

However, strep A bacteria can also ambush patients a few weeks after these milder infections, causing severe, lifelong complications – including rheumatic heart fever or inflammation of the kidneys. These complications are more common in certain populations, such as those who are homeless or living in poverty, or people with drug and alcohol use problems.

Strep A bacteria can also cause more severe illnesses, including scarlet fever, sinusitis, pneumonia, cellulitis, bone and blood infections.

In rare cases, strep A bacteria can spread from cuts and wounds deep into soft tissues and muscle, leading to necrotising fasciitis or “flesh-eating disease”. And streptococci can in some situations release immune-activating toxins that activate the immune cells in tissues, triggering STSS.

Toxic shock

STSS patients often complain initially of fevers, muscle aches and nausea, before becoming confused or drowsy. Low blood pressure follows, leading to cold hands and feet, a rapid heart rate and breathing too. Without the blood pressure they need to function, organs then begin to fail, usually 24 to 48 hours after the symptoms emerged.

STSS has a high mortality rate – ranging from 5% in younger patients who have been admitted quickly to intensive care, to up to 70% in the elderly.

Patients need to be treated as soon as possible.
goodbishop/ Shutterstock

Treatment for suspected STSS should be delivered as rapidly as possible. Patients will require oxygen, intravenous fluids and even cardiac support, alongside antibiotics and intravenous immune antibodies to deactivate strep A toxins. Even if referral and treatment is given quickly, it may still take patients many weeks to recover from the physical effects.

STSS is more common in people who have a poor immune system– including the elderly, people taking steroid medications, people recovering from a recent illness (particularly chickenpox), those with type 2 diabetes, and people with drug and alcohol problems. The elderly are a large and growing component of Japan’s population, which may explain why cases of STSS are particularly high there.

The rise in STSS cases is probably also a consequence of fewer COVID restrictions in this post-lockdown period. Public health measures such as mask wearing, washing and disinfecting hands and social distancing all helped to reduce the spread of strep A bacteria. People were exposed to larger numbers of bacteria when these controls were lifted.

Fortunately, strep A bacteria remain responsive to penicillin, although resistance has been identified in some strains. This means that strep A – and STSS – remain treatable.

Researchers are also working on developing a protective vaccine against strep A bacteria. If successful, this would not only protect against milder illnesses caused by streptococci, but also against rheumatic fever and perhaps the more acute severe illnesses such as STSS.

Strep A bacteria are estimated to contribute to more than half a million deaths globally each year. While relatively few of these are the consequence of STSS, this number highlights a need to better monitor group A streptococci, their evolution and the diseases they cause.

Protecting yourself against strep A bacteria remains relatively simple. Many of the practices we followed during the height of the pandemic – such as wearing masks, washing hands and avoiding crowds – can help us avoid strep A too. Läs mer…