– People with malaria parasites produce specific smells on the skin. We have found that dogs that have a sensitive nose can be trained to detect these smells. It also applies to clothing worn by infected people, said Steven Lindsay of the Department of Biosciences at the University of Durham in the United Kingdom and principal investigator of a new study on malaria.
Recently, he presented his findings at the annual meeting of the American Society for Tropical Medicine and Hygiene.
Smelled in stockings
Several hundred children from Gambia participated in the new survey. First, they went through a general health check, then they were tested for malaria parasites. After that, they got a pair of socks to wear during the night. The next day, the researchers collected the socks and divided them into malaria child infection status. They only collected socks for malaria-infested children without the symptoms and socks of young children. The socks were shipped to England. There they were frozen while the sniffer dogs were trained.
The sniff test was about to distinguish between socks for healthy and saturated malaria children. They should sniff each pair of socks and freeze if they think they have found malaria mites. If they do not smell something, they should move on.
The test results showed that dogs were able to identify 70% of the socks of malaria infested children and 90% of healthy ones.
Mutation of the malaria parasite
Researchers say the accuracy of the impact is impressive and that dogs have been able to identify socks for children with lower infection levels than required by the World Health Organization (WHO) rapid tests.
In general, the diagnosis of malaria is made using blood samples and microscopy. It can be time consuming and special skills are needed. You can also use rapid blood tests, but these are very expensive. They have a high level of accuracy.
The researchers were aware that this was a concept proofstudy, to demonstrate that malaria can be diagnosed by dogs. They also believe that the accuracy of sniffer dogs can be as good as blood tests. Lindsey justifies this because malaria parasites in children are not always the same type that go through different stages of the disease. The scent they create on human skin changes.
He points out that the tests used today may also be short because the malaria parasites are transformed. Thus, parasites may not have the specific protein required for clinical testing to show infection
In addition, researchers believe that the ability of sniffing dogs to detect certain odors associated with malaria can be an inspiration in the development of emerging and artificial electronic noses that can smell disease.
Border guard dogs
Lindsey believes that sniffer dogs can be useful when health officials want to check villages for malaria sufferers who have no visible symptoms. By being a carrier, you can transfer malaria parasites to the local mosquitoes. The only way to prevent the spread today is to test or cure everyone in a village.
The researchers behind the research, therefore, believe that sniffer dogs would work well at border crossings, to countries where malaria is almost eradicated. Lindsey designs on the island of Zanzibar, in East Africa, where elimination of the malaria parasite has been difficult due to a steady stream of immigrants.
Very little accurate
Gunnar Hasle is an infectious disease specialist and operates the Reiseklinikken in Oslo. He says the preliminary hit rate of 70% is very low.
"This means that the method is useless to find out if a person with a fever has malaria because it is not acceptable to complete the errors by 30%.
It also points out 90% of those who are healthy and 10% get an incorrect message about malaria.
"It's an unacceptably high number if the method is used to smell a large number of healthy people," he says.
Blood examination at the clinic, dogs at the border
Hasle also claims that odor indications have been used for hundreds of years. It is possible, among other things, to succeed in diabetes, by acetone inhalation or enamel remover. In addition, it is possible to smell liver failure because the spirit smells sweet.
"It has also been tried to get dogs to diagnose lung cancer," said Hasle, referring to a 2012 survey. The result was almost the same as in the malaria trial.
He believes it is totally impossible to use dogs to diagnose clinics and that, however, it will be difficult to train enough dogs to meet the need.
– Any health facility in the tropics should have access to the malaria diagnosis. So it is much easier to get quick tests that you can use after minimal training than trained dogs.
He, however, believes that they can help in some cases, and support the researchers' thinking of using sniff dogs as malaria guards.
"Sniffing dogs can be used for mass screening on immigration to an area that has eradicated malaria," he concluded.