Two new studies have now backed the hygiene hypothesis, which shows rising rates of diabetes and asthma are linked to obsession with cleanliness. 

One of the studies says Finland's rising rates of Type-1 diabetes is linked with the country's high levels of sanitation. The second study from Germany, conducted on rodents, shows the mechanism by which Salmonella infection can mitigate asthma severity.

Note that the study exclusively highlighted the incidence of Type -1 diabetes to cleanliness.

Hygiene Hypothesis

Recently, there has been a lot of interest in the "hygiene hypothesis". The idea is that people who aren't exposed to common germs have poor immune system, which in turn leads to several other health problems. Recently, Cambridge University researchers and their colleagues had found a link between sanitation and higher incidence of Alzheimer's disease. However, their study didn't show a cause-and-effect relation. Also, diseases such as dementia, asthma, eczema and diabetes have several risk factors, which is why it is difficult to independently link sanitation with these conditions.

Cleanliness and Diabetes

The study on diabetes type-1 and sanitation was conducted by researchers at the University of Helsinki. The team, led by Mikael Knip, collected blood samples from 3,500 children - from Finland, Estonia and Karelia, which was once part of Finland, according to South China Morning Post.

Researchers found that although children from the three regions shared same genes and language, the rate of diabetes type-1 was different. Data analysis showed that Finland's diabetes rate is about six times higher than Karelia's. Knip and team believe that the higher rate might be linked with higher sanitation in Finland, SCMP reported.

Salmonella and Asthma

Salmonella is the quintessential "eek germ" and is a common cause of food poisoning. The bacteria live in human and animal intestine and are shed along with feces. Food or water contaminated with this bug can cause severe diarrhea and fever. Healthy individuals recover within 4-7 days after infection.

Previous research has shown that children who've had salmonella infection have lower risk of asthma.

In the present study, researchers led by Venkateswaran Ganesh, wanted to find the mechanism behind this reduced risk.

Ganesh and team had earlier found that Salmonella infection correlated with low levels of inflammation in the airway.

Now, Ganesh and colleagues found that the reduction in asthma severity was linked with low levels of interleukin-4 in the body. Interleukin-4 is an inflammatory compound produced by T helper-2 cells.

Ganesh also found that a type of cells in the bone marrow were responsible for the T helper-2 cells producing less Interleukin-4.

"By performing cell culture assays and studies in rodents, we could determine the influence of myeloid cells on Th2 cells," he explained in a news release.

The study is published in the journal Infection and Immunity.