Tuberculosis - An Old Disease with a New FaceTuberculosis transmission routes and unexpected sources of infection
Be careful of poorly ventilated locations
The bacterium that causes tuberculosis (TB), mycobacterium tuberculosis, is spread through the air when people who have active tuberculosis cough or sneeze, and other people then breathe in the bacteria (Airborne Infection、Droplet Nuclei Infection). The disease is not spread by holding hands with someone who is infected, or by using the same tableware etc.
Because TB germs released into the air can linger for an extended period in locations with poor air conditioning or ventilation, there have been cases of the disease spreading even when the infected person is no longer present.
Large cities where many people live and work together in close quarters have high risks of infection due to their very nature. Moreover, with the recent increase in homelessness, and the lack of healthcare that accompanies it, combined with an increase in the number of foreign workers from countries with high rates of TB infection, we see a difference in the spread of TB in large cities compared with rural areas (figure 4).
Figure 4 - Trends in Tuberculosis Infection Rates in Several Cities
Factors Which Increase the Risk of Becoming Infected
- Infancy and pubescent children
Infants, with their weaker immune systems, can easily succumb to TB if they become infected. These children are at a greater risk of suffering serious complications and thus require special attention.
It is believed that stress and irregular lifestyle patterns can also make one more susceptible to TB.
- Gender Differences
Women are more susceptible to the disease before middle age, and men become more susceptible after reaching middle age.
- Diabetes, Stomach Ulcers, and Other Conditions
People with diabetes or stomach ulcers, or those who have had a gastrectomy, are known to be more susceptible to TB. In addition, those with pneumoconiosis, those who have undergone intestinal bypass operations, those undergoing dialysis, or those with hemophilia are also said to be vulnerable.
- Adrenocortical Hormone Agents, Biological Drugs
Anti-cancer drugs and adrenocortical hormone agents (steroids) used to treat asthma, collagen disease, cancer, and other disorders can weaken the immune system and increase the user's risk of contracting TB. People using TNFα inhibitors (biological drugs), currently receiving attention as a treatment for rheumatoid arthritis and other disorders, have also been recognized worldwide as being more susceptible to the disease.
- AIDS, HIV Infection
In Africa and some Asian countries, the presence of populations with weakened immune systems due to HIV, has led to increases in the number of TB infections, and become a serious issue.
- Hereditary Predisposition
Science is gradually uncovering information indicating that resistance to TB is genetically determined.
- Tobacco and Other Factors
Smokers, people who have contracted tuberculosis in the past, people who have not received the BCG vaccination and received positive results from tuberculin tests, people with others close to them who have recently contracted TB, and individuals in similar circumstances are also at a higher risk of contracting the disease.