‘BREAKTHROUGH’ IN FIGHT TO END DISEASE CAMELS PASS TO HUMANS
The Central Veterinary Research Laboratory in Dubai finds reliable ways to test camels for brucellosis, writes Daniel Bardsley
Camels have provided milk, meat, labour and companionship to the people of the Gulf far back into history, helping the Bedouin survive in a region where nature can be harsh.
Given that the animals are woven into the fabric of the region’s history and identity, it is perhaps no surprise that many Emirati families preserve pastoral traditions by keeping small herds of them.
There are more than 20,000 small livestock holdings in Abu Dhabi and official figures show they hold about 3.4 million camels, sheep and goats.
But the small farms, often run partly for leisure, do bring health risks – diseases people can catch from the animals. One of these is brucellosis.
Human brucellosis infections cause symptoms similar to influenza and, while antibiotics can treat it, some cases lead to complications such as heart problems, arthritis and brain inflammation. Human brucellosis can, in extreme cases, be fatal. It can also become a chronic condition.
Brucellosis is found across the Middle East and parts of Asia, Africa, Central and South America, and other regions.
There were 480 cases in the UAE between 2010 and 2015, according to research published last year in the journal BMC Infectious Diseases.
Four researchers at UAE University in Al Ain and another doctor at Khasab Hospital in Oman used data from the electronic reporting system that was introduced in 2009, revealing a rate of 3.3 for every 100,000 people.
People can get brucellosis from unpasteurised milk or untreated dairy products, or even from having direct contact with infected animals.
In their paper, Nawal Al Shehhi, who is based in Oman, Faisal Aziz, Farida Al Hosani, Bashir Aden and Iain Blair wrote that the source is likely to be the small farms, where hygiene standards vary.
They found that Emiratis, of any age, were particularly at risk – because they often keep camels and other animals that carry brucellosis – as were expatriate men of working age in the Eastern Region.
In the capital, between 5 and 9 per cent of camels are thought to be infected, according to a 2009 study quoted in the paper.
And because person-to-person spread is rare, eliminating the disease from livestock would be a key step towards reducing infection rates in people.
One tactic to eliminate brucellosis is to test herds for it and cull those beasts that are infected. Typically such animals cannot be cured.
But tests tend to be optimised for animals other than the camel. This is where the Central Veterinary Research Laboratory can help.
The lab’s scientific director, Dr Ulrich Wernery, and a doctoral student, Nina Soellner, have recently completed a project to identify which among the myriad available brucellosis tests are the most reliable when used with camels.
It was a major undertaking involving thousands of samples from 40 camels donated by Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai. They were given a brucellosis infection, directly into their trachea or their noses, and kept at a quarantined site.
“The bacteria more or less went straight into the lungs,” Dr Wernery says. “It’s a normal infection route. Normally they inhale the bacteria. They developed the disease.”
Every two weeks for a year, blood samples were collected and checked for brucellosis using 15 different tests. Nine thousand samples were tested.
“Only two were reliable tests, so 13 failed. That was very interesting because you cannot use these 13 test kits for the diagnosis of camel brucellosis,” Dr Wernery says.
The two tests that worked involved an enzyme-linked immunosorbent assay test and a Rose bengal test.
“These were the most sensitive tests. Ten days after the infection the tests showed a positive reaction but not all were detected. A couple of days later all 40 animals were detected with these tests, whereas all the other tests failed,” Dr Wernery says.
“Some other tests detected the first animals only after 30 days; some only after 60 days. Some didn’t detect all of them, only 80 per cent of them.”
He says it was a “breakthrough” that “reliable, sensitive and specific” tests have been identified for the diagnosis of brucellosis in camels.
“Normally the positive animals are culled; there’s no treatment. They are killed and burnt. That’s very bad and there’s not really a good vaccine,” Dr Wernery says. “With these tests you can say 100 per cent, ‘These are negative and these are positive’, to avoid culling negative animals.”
Dr Wernery, who caught brucellosis three years ago and was treated for six months to ensure he was cured, says authorities would like to eliminate brucellosis from the UAE’s camels and livestock.
As long as it is found in animals, people will continue to catch the disease. Dr Wernery says elimination is achievable.
“We had brucellosis in western Europe 40 years ago,” he says. “We got rid of it by culling millions of animals. Now western Europe is free of brucellosis. You can only get rid of it when you have the right tests,” he said.