At least 79 infants born in Rome’s Gemelli Hospital have tested positive for tuberculosis (TB). A nurse in the neonatal ward recently tested positive, and all 1,271 infants born at the hospital between March and July are now being screened. More cases may be identified as this process continues.
Prosecutors have reportedly launched an investigation and local media have raised the question of “blatant negligence,” but it is not yet clear if the hospital failed to test the nurse before hiring or if the individual acquired TB once employed there. A hospital official stated the nurse had been previously vaccinated.
When exposed to a person with TB disease, healthy adults are not easily infected, but children under the age of 2 are considered to be at greater risk due to their weaker immune systems. TB is a curable disease, especially when an individual starts medication before becoming sick.
WHO data states 1.7 million people died from tuberculosis in 2009, with the greatest number of deaths in Africa and South-East Asia. Roughly one third of the world’s population is infected with TB.
What’s the difference between being infected with TB and having TB disease?
Among healthy adults who become infected with TB, only 5-10% will immediately become sick with “primary tuberculosis.” The other 90-95% have immune systems that will successfully contain the tuberculosis bacteria. This means they are infected by the TB organism, but it is walled off and not causing illness. These individuals have “latent TB”; they are not sick, and cannot transmit TB to anyone else. Occasionally the immune system of someone with latent TB will stop containing the TB, and they will develop active illness (“reactivation” of tuberculosis). Due to this possibility, people with latent TB are treated so that they cannot become sick and transmit TB in the future.
If it’s so hard to get, then why is it so common?
As mentioned above, only 5-10% of healthy individuals become sick if infected with TB. Among HIV+ individuals who are infected with tuberculosis, roughly 40% develop active disease within several months. This is due, in part, to the weakened immune system of an HIV+ person. Tuberculosis cases had been on the decline in many parts of the world before the HIV/AIDS epidemic essentially made TB more common. Other diseases, malnutrition, and stress have all been suggested as risk factors for becoming infected with TB and progressing to disease.
Although tuberculosis is an ancient disease, its spread beyond the Mediterranean and Europe is more recent. Tuberculosis was rare in Africa in the early 1900s with Europeans spreading the disease slowly with colonialism. Tuberculosis spread to Asia in the 1900s as well. The parts of the world that have most recently been infected are the areas with the highest number of cases.
The nurse was vaccinated. Why didn’t that prevent TB? And why don’t Americans get vaccinated?
The Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis is widely used throughout the world, but its efficacy is variable. A review of previous studies indicated the BCG vaccine reduces the risk of tuberculosis by only half. A difficulty with the vaccine is that it can cause people without TB infection to test positive for TB on the standard skin test used in the United States. A consequence of widespread vaccination would be a large decrease in the reliability of the standard test for TB. Because the US has relatively few TB cases, many specialists feel widespread vaccination could actually make it harder to identify and treat cases of latent TB, which could ultimately lead to more cases.