– People with malaria parasites produce specific odors in the skin. We have found that dogs who have a sensitive sense of smell can be trained to detect these odors. This also applies to clothing used by infected people, said Steven Lindsay of the Department of Biosciences at the University of Durham in the United Kingdom and the chief investigator responsible for the new study on malaria.
Recently, he presented his findings at the annual meeting of the American Society of Tropical Medicine and Hygiene.
He pulled on his socks
Several hundred students from Gambia participated in the new survey. First, they were subjected to an overall assessment of health, and then examined for malaria parasites. Then they got a pair of socks that you can use for the night. The next day, scientists collected socks and divided them into malaria infection status in children. They collected socks only for children infected with malaria without the symptoms and socks of fresh children. The socks were then sent to England. Here they were frozen, while the smelling dogs were trained.
The sniffing test was to distinguish between socks for malaria and healthy children. They should smell each pair of socks and freeze if they think they have found malaria mites. If they do not feel something, they should go on.
The result of the test showed that dogs were able to identify 70 percent of socks of children infected with malaria and 90 percent of healthy socks.
Malaria parasites mutate
Researchers say the impact accuracy is impressive and that dogs were able to identify socks for children with a lower infection status than required by the rapid tests of the World Health Organization (WHO).
Generally, the diagnosis of malaria is made using blood samples and microscopy. This can be time-consuming and special skills are needed. You can also use quick blood tests, but they are quite expensive. They have a high level of accuracy.
The researchers were aware that this is so-called proof of conceptto show that malaria can be diagnosed by dogs. In addition, they believe that the accuracy of sniffing dogs may be as good as blood tests. Lindsey justifies this because malarial parasites in children are not always of the same type as the different stages of the disease. The smell that forms in human skin changes.
He indicates that tests used today can also be short because malaria parasites mutate. Therefore, parasites may not have the specific protein necessary to show infection in clinical trials
What's more, the researchers believe that the ability to smell dogs to detect certain malaria-related odors can be an inspiration for developing emerging and artificial electronic noses that can sense disease.
Dogs guard malaria on borders
Lindsey believes that sniffing dogs can be helpful when health authorities want to check villages for malaria carriers that have no visible symptoms. Being a carrier, you can transfer malaria parasites to local mosquitoes. The only way to prevent the spread today is to test or treat all the villagers.
Researchers responsible for the study therefore believe that smelling dogs will do well at border crossings, in countries where malaria is almost eliminated. Lindsey draws from the East African island of Zanzibar, where the elimination of the malaria parasite was difficult due to the constant influx of immigrants.
Too little accurate
Gunnar Hasle is a specialist in infectious diseases and operates Reiseklinikken in Oslo. He says the initial hit rate of 70 percent is too low.
"This means that the method is useless to find out if a person with fever has malaria, because it is unacceptable to find errors at the level of 30 percent.
It also indicates 90 percent of healthy, and 10 percent gets an incorrect malaria message.
"This is an unacceptably large number if the method is to be used to detect many healthy people," he says.
Blood test in the clinic, dogs on the borders
Hasle also claims that odor indications have been used for hundreds of years. Among other things, it is possible to achieve success in diabetes by breathing the smell of acetone or nail polish remover. What's more, you can sense liver failure because the ghost has a sweet smell.
"It was also tried to get the dogs to diagnose lung cancer," said Hasle, referring to the 2012 survey. The result was more or less the same as in the malaria study.
He believes that it is completely impossible to use dogs to diagnose clinics, and yet it will be difficult to train enough dogs to meet their needs.
– Every healthcare unit in the tropics should have access to diagnosing malaria. Then it is much easier to get quick tests that can be used after minimal training than after trained dogs.
He believes, however, that they can help in some cases, and support the thought of scientists to use sniffing dogs as guards of malaria.
"Sniff dogs can be used for mass selection on immigration to an area that has eradicated malaria," he concluded.