Sweet berry leads to sour ordeal as SA records first karaka poisoning case

A woman who ate a tasty orange berry from a tree in her Cape Town garden went on to experience eight weeks of agony.

A doctor initially thought the 46-year-old was having a panic attack when she reported dizziness, a numb mouth and a racing heart, and prescribed lorazepam to calm her.

But she started experiencing tingling in her arms and intense headaches. After she told her GP about the berry, it was identified as the fruit of a karaka tree, native to New Zealand.

Even though the flesh of the karaka berry is sweet and delicious, the kernel is highly poisonous. Evidence of the toxin was found in the woman’s hair several weeks later.

Eight long weeks after eating the berry, she finally made a full recovery from what is believed to be the first case of karaka poisoning in SA.

The drama is reported in a SA Medical Journal article by Dr Daniel Watson and colleagues from the clinical pharmacology division in the health sciences faculty at the University of Cape Town.

It was here that high-resolution mass spectrometry techniques matched the toxin in the patient’s hair with the karaka kernel after a battery of other tests failed to diagnose her problem.

“Investigations including electrolytes, calcium, as well as her renal and liver function, were all normal. A computed tomography scan of her head showed no abnormalities. Despite symptomatic therapy her condition continued to worsen,” said Watson.

At this point, the GP decided the berry the woman had eaten needed further investigation.

“A cutting of the tree was identified by a horticulturist at Starke Ayres Garden Centre ... as the karaka tree,” said Watson.

The GP then asked the toxicology unit in Watson’s division for help and supplied urine, blood, saliva and hair samples for analysis, as well as a berry from the woman’s tree.

High-resolution mass spectrometry combined with the PubChem open chemistry database at the National Institutes of Health in the US showed the berry’s kernel and the woman’s hair contained karakin, a potent neurotoxin.

“Hair is an extremely useful matrix to analyse in toxicology as it has a larger surveillance window of days to weeks, compared to that of blood or urine, which is usually only a few hours to days,” said Watson.

A standard toxicology screen would not have detected karakin, he said, because there are no regular tests for it, “and to our knowledge it has never been previously reported in a poisoning case in SA”.

Prof Brian van Wilgen of the Centre for Invasion Biology at Stellenbosch University told TimesLIVE Premium the karaka tree is an alien species but is not listed in the environment department’s invasive and alien species regulations.

“There are several ‘mistakes’ in the regulations — for example, species listed but not recorded in SA, or species listed with incorrect names and so on — so we need each species to be thoroughly vetted before it goes on to the list,” he said.

Van Wilgen said his organisation and the SA National Biodiversity Institute are developing a comprehensive list of alien species. “It is early days, and the karaka tree is not on the list yet, but obviously it is here,” he said.

It joins several other poisonous alien plants, including oleanders, syringas and the parthenium weed and lantana. Van Wilgen said:

• “The oleander is from the Mediterranean region and has been widely planted in SA as a garden plant and along highways. Ingesting a single leaf can be fatal. It is listed in the regulations as category 1, so people are not allowed to own or sell it, and people are obliged to remove it if it is in their gardens or on their land. The problem is that ‘sterile cultivars or hybrids’ are exempt because they don’t produce seeds and are therefore not invasive, but they remain toxic.”
• “The ripe fruits of syringa trees are also highly toxic, and ingestion can be fatal. Syringas are from the Middle East and alien in SA but widely planted. They are listed as invasive aliens in the regulations, but specimens in gardens are exempt and may be retained.”
• “Parthenium weed from Central America is an alien herbaceous plant that is spreading rapidly in the east of SA. It is a listed species in the regulations and can cause serious allergic reactions in humans and animals.”
• “Lantana is another listed invader from South and Central America that has toxic fruits and is a skin irritant.”