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Dogs are often carriers of disease - threatening miniature threadworm infections
Dogs are generally considered the best friend of humans and often live closely with their owners. Thus, pathogens from the four-legged can easily pass on humans. According to a recent study, this also applies to the miniature threadworm Strongyloides stercoralis, whose infections can be particularly dangerous for people with a weakened immune system.
Scientists at the Max Planck Institute for Developmental Biology in Tübingen, Germany, in collaboration with colleagues from the Swiss Tropical and Public Health Institute in Basel and the Cambodian Ministry of Health, investigated the number of miniature threadworm infections in dogs and humans. The molecular-biological analysis of the miniature threadworm Strongyloides stercoralis showed that the pathogens can be transmitted between humans and dogs. The researchers published their study results in the journal "PLOS Neglected Diseases".
Dogs can transmit various parasites to humans, including the miniature threadworm Strongyloides stercoralis. (Image: cristina_conti / fotolia.com) 300 million people worldwide infected
The nematode worm infections caused by the roundworms are on the WHO list of neglected tropical diseases, according to the researchers. The dwarfed worm Strongyloides stercoralis is especially common in humid regions of the world and affects both humans and animals. According to the researchers, about 300 million people worldwide are infected with miniature threadworms. The result is a so-called strongyloidasis, which can be dangerous especially for people with a weakened defense system, for example, after organ transplantation or immune system diseases.
People and pets share their parasites
Surely people and dogs share their parasites, according to the researchers, but it has remained unanswered whether the miniature threadworm infections are to be assessed as such zoonosis. Not least because the different pathogens of the species are so similar that they can only be distinguished from one another by a genetic analysis. In their recent study, the researchers used such a genetic analysis to investigate "whether humans and dogs in Cambodia are infected with the same species of the monkey threadworm Strongyloides stercoralis, or whether they are separate host-specific populations."
Genetic analysis of the miniature threadworms
According to the scientists, the close coexistence of humans and dogs in the rural areas of Cambodia, combined with the high Strongyloides occurrence, was particularly well-suited to determining "whether the miniature threadworms found in dogs are genetically identical to those of their owners." The researchers isolated worms from dog excrement and human stool samples and compared the specimens found using nuclear and mitochondrial DNA to sequence polymorphisms, according to the Max Planck Institute.
Dwarf threadworm infections are a zoonosis
In dogs, the researchers were able to detect two different worm populations, which are genetically clearly separated. The larger populations could only be detected in dogs, while the second Strongyloides population was genetically identical to the type of virus found in humans. Thus, the miniature threadworm infection is classified as a zoonosis. "The results of the current study show that because of the overlapping populations, dogs must be considered as a reservoir and therefore a source of infection for human strongyloides infections," reports the Max Planck Institute. This knowledge is important for the fight against Strongyloides infections in humans.