SOUTH HADLEY — The number of positive tests for latent tuberculosis in South Hadley jumped significantly last fiscal year, though state and local health officials say there’s no cause for alarm at this time.
Town officials say the heightened number of cases — there were 16 confirmed and five suspected cases between July 1, 2016, and June 30, 2017, according to the town report — is not a result of an outbreak in the community, and that none of the patients tested has an active case of the disease. There were two latent cases in South Hadley the previous fiscal year.
“Most people don’t even get sick from latent TB infections,” said Andrew Tibbs, an epidemiologist with the state Department of Public Health. “There’s no risk of spreading the disease while it’s in the latent phase so we wouldn’t consider 16 cases of latent TB to be an outbreak or to be at all a public health concern.”
Tuberculosis in its active form is a contagious airborne disease that usually infects the lungs, but can also affect a person’s brain, kidneys and spine, according to the Centers for Disease Control and Prevention. Symptoms include persistent coughing, chest pain, night sweats, chills and weight loss.
Latent tuberculosis is not contagious and anyone who has it can take medication to cure it, according health experts.
A serious illness, traumatic event or physical accident could trigger the active form of the disease in someone with the latent form, according to Sloan Siegrist, an assistant professor of microbiology at the University of Massachusetts Amherst. Additionally, people living with HIV and elders have a heightened risk of developing tuberculosis due to their suppressed immune system.
“It’s not usually a problem unless you become immunocompromised in some way,” Siegrist said.
She estimates that 5 to 10 percent of latent tuberculosis patients develop active tuberculosis.
Those who tested positive for the latent form of the disease in South Hadley — no one has an active case — are neither contagious nor do they require immediate treatment, said Margaret Bernard, the town’s community health nurse.
“When you have been exposed to TB there’s bacteria that is hidden, for lack of a better word, in your body,” Bernard said. “It does not harm you, it does nothing to cause you any issue but at some point in the future it may.”
Bernard said 16 positive tests in one year is higher than average, and the cases were found across all age ranges and demographics.
Every municipality in the county reported cases of latent tuberculosis, between two and 105 cases, in that timeframe, according to state health officials, though the state does not track numbers for individual communities other than the top 25 cities and towns by population out of privacy concerns, Tibbs said. “The numbers are too small for TB disease to report on a municipality level since 2013 for any municipality in Hampshire County.”
Last year in Massachusetts, the DPH reported 210 cases of active tuberculosis, a 10.5 percent increase from the year prior.
In Hampshire County, five municipalities each reported fewer than five cases of active tuberculosis within the past five years, while 11 communities reported no cases, DPH said. South Hadley had none.
But since 2013, South Hadley has reported more than 50 confirmed and suspected latent cases, according to DPH.
State health officials aren’t able to definitively say why South Hadley has seen such an increase in the number of latent cases, but experts speculate that it could be the result of increased testing, a change in the consistency with which local physicians report positive tests, or a national push to target populations susceptible to the disease with early detection.
Recently, the U.S. Preventive Health Services Task Force made latent tuberculosis testing a grade B procedure, meaning it can be covered by insurance companies with no-out of pocket costs, according to the state Department of Public Health.
“I would guess that South Hadley has seen either a local increase in testing due to a policy change (schools, universities, etc.), which results in more cases being reported, and/or a new provider either moved into the community and/or learned about the requirement to report TB infection for the first time,” Tibbs said in an email. “These two things alone or in combination could yield an increase in the absolute number of reports.”
The only true tuberculosis outbreak in western Massachusetts in the last decade was in Springfield in 2009, when over 20 people fell ill to the disease, according to Tibbs. The majority of patients were from outside the U.S., according to data from the CDC’s Division of Tuberculosis Elimination.
Last year Siegrist received a $2.3 million grant from the National Institutes of Health to study the tuberculosis bacteria, how the disease grows and is treated with antibiotics.
A person’s skin or blood can be tested for the presence of the bacteria, mycobacterium tuberculosis, she explained. Three days after the test is administered, a raised and reddened area would indicate a person has come in contact with the bacteria at some point in their life.
When an active case of tuberculosis is detected, immediate steps are taken by local and state boards of health to identify everyone that individual may have come in contact with at home, work, school, or elsewhere in daily life. Those people are then encouraged to get tested and potentially seek treatment as well.
A person hospitalized for tuberculosis will stay in quarantine for about two weeks while receiving treatment, then continue taking medication after being discharged and no longer contagious, according to the CDC.
Every positive test for tuberculosis in the U.S. must be reported by the testing physician to the local and state public health departments. According to the CDC, delays in reporting suspected tuberculosis cases can increase the chance of an outbreak.
Tuberculosis is less common in North America than elsewhere in the world, and can make its way into the U.S. via international travelers.
Tibbs said specific subgroups of the Massachusetts population are at a greater risk of developing tuberculosis, and those populations are targeted with increased testing and preventative therapy, perhaps explaining the increased number of positive tests in certain communities.
“You have people coming in internationally for school, you have people immigrating from other countries,” said Bernard, South Hadley’s nurse. “A lot of people I have had experience with, they’re not U.S. born. Sometimes they have been here a while and sometimes they just arrived.”
About one-third of the world’s population is infected with tuberculosis bacteria, but only a small proportion of those infected will become sick with the disease, Siegrist said. According to the World Health Organization, there were 6.3 million cases of tuberculosis worldwide in 2016, with a treatment success rate of 83 percent.
“TB is not a public health concern but if you are interested in your own risk for TB you should speak with you provider and discuss the risk with them,” Tibbs said. “You may have had a risk of exposure in your lifetime.”
Sarah Robertson can be reached at srobertson@gazettenet.com.