The Ticking Time Bomb of Latent TB Infection Among Sub-Saharan Refugees in Minnesota

Extraordinarily high levels of latent TB infection among Sub-Saharan refugees who have arrived in Minnesota during the past decade appear to be the ticking time bomb that has exploded into 296 cases of active TB diagnosed in the state among refugees in the past five years.

The majority of those cases of active TB among refugees, 161, are Somali-born.

Between 2004, when the Minnesota Department of Health (MDH) first began publicly reporting this data, and 2010, the latent TB infection (LTBI) rate among the more than 11,000 refugees from Sub-Saharan Africa (almost all from Somalia) resettled in Minnesota during those seven years ranged from 55 percent in 2004, to 40 percent in 2010, according to MDH. In 2014, the LTBI rate for Somali refugees declined to 30 percent, which still remains a very high rate, even among resettled refugees.

The rates of LTBI among Somali refugees who arrived in Minnesota during this seven year period are significantly higher than LTBI rates for refugees reported in other states, which range from 12 percent in California to 35 percent in Vermont.

In 2004, 34 percent of all arriving refugees in Minnesota tested positive for LTBI. In 2014, 22 percent of all arriving refugees in the state tested positive for LTBI.

As a point of comparison, only four percent of the general population in the United States tests positive for latent TB infection. Five to ten percent of the general population that tests positive for LTBI develops active TB at some point in life, according to the Centers for Disease Control.

The 296 cases of active TB diagnosed in Minnesota in the past five years among refugees is at a level that is ten times higher than any of the fourteen other states for which Breitbart News has been able to obtain data. (Thirty-six states have not made this data publicly available.)

MDH confirmed the data Breitbart News reported, but blamed the ten times greater rate of active TB cases among refugees in the state on “the American diet and lifestyle,” as well as the state’s superior tuberculosis reporting information system.

“Oftentimes the reason that Minnesota reports TB and other infectious diseases at higher rates than other states is because we have a stellar system of surveillance and screening,” the MDH said in a statement provided to Breitbart News. In other words, it may be nearly as bad in other states; they just aren’t tracking it.

But extraodordinarily high rates of latent TB infection among arriving refugees, and Somali refugees in particular, combined with relatively low completion of treatment for LTBI among those refugees who arrived in the state between 1990 and 2010, may be a more plausible explanation for why Minnesota’s rate of active TB among refugees is ten times greater than any other state.

As Breitbart News reported, a landmark 2013 study from the University of California at San Diego “analyzed data from LTBI [latent tuberculosis infection] screening results of 4,280 refugees resettled in San Diego County between January 2010 and October 2012,” and concluded that “[t]he prevalence of LTBI was highest among refugees from sub-Saharan Africa (43 percent) and was associated with current smoking and having a clinical comorbidity that increases the risk for active tuberculosis.”

Despite compelling evidence to the contrary that high rates of latent TB infection among arriving Somali refugees is the primary cause of heightened rates of active TB among the refugee communities in Minnesota, MDH remains unpersuaded of causality.

Breitbart News asked MDH if it considers “the American diet and lifestyle” the most significant cause of other medical conditions that cause latent TB to activate among refugees, or if their pre-existing health conditions prior to arrival, such as high rates of latent TB infection, were a more significant cause.

“We do not have sufficient data or information to assess whether development of risk factors for activation of latent TB occurred before or after U.S. arrival for Minnesota’s foreign-born TB cases,” MDH responded.

“This statement by MDH seems to be an answer to an irrelevant question,” Dr. Jane Orient, executive director of the Association of American Physicians and Surgeons, told Breitbart News, adding, “The relevant facts are: TB was acquired in Somalia. The ‘risk factor’ for having active TB is the tubercle bacillus. People with latent TB have the tubercle bacillus. Anything that weakens the immune system can activate the TB. I know of no evidence that the American diet or lifestyle has anything to do with it. Malnutrition, immune-suppressing drugs, some other infection can do it. Maybe cold weather can.”

“People with latent TB are a public health risk. They need a full course of treatment and periodic monitoring, as with chest x-rays. One case of active TB requires a huge investment of public health resources to find and test all contacts,” Orient added.

The entire MDH response states (emphasis added):

The sentence you referenced in MDH’s initial statement refers to the phenomenon described in peer-reviewed public health literature as the “healthy immigrant paradox.” In general measures of population health, such as infant mortality, infant birth weight, and life-expectancy, immigrants overall tend to be healthier than those who were born in the United States. This is also true for prevalence of chronic diseases. This health advantage dissipates the longer immigrant groups have been in the United States. There are, of course, variations within sub-groups of immigrants, but this phenomenon is observed both in the United States and in other industrialized countries. While the phenomenon is well-defined, explanations for what causes it are varied. This article by Uretsky and Mathiesen (2007) provides a good explanation of the healthy immigrant paradox.

Regarding tuberculosis, risk factors for activation of latent TB include several chronic diseases such as diabetes, cancer, end-stage renal disease, and other immunocompromising conditions. We do not have sufficient data or information to assess whether development of risk factors for activation of latent TB occurred before or after U.S. arrival for Minnesota’s foreign-born TB cases. The data MDH collects are on conditions present at or around the time of TB diagnosis.

Please note about the study you cited: [Chronic Disease Prevalance of a Refugee Population in Dayton, OH]

The study was not peer-reviewed literature, but was someone’s thesis project from a university library archive and is specific to one geographic area, Dayton, OH. It is not representative of Minnesota’s refugee population.

Despite MDH’s unwillingness to admit what common sense confirms, untreated LTBI among Minnesota’s refugee population is a ticking TB time bomb that has been exploding in the state since 1993, and it may not be done causing damage. The potential that many of the thousands of refugees who arrived in Minnesota with LTBI since 1990 and have never been treated will develop into active TB cases remains a significant health concern for all Minnesotans.

While the number of active TB cases reported in the United States declined for 22 consecutive years between 1993 until 2014, “the incidence of TB in Minnesota increased throughout much of the 1990s and peaked at 239 TB cases (4.8 cases per 100,000 population) in 2001,” MDH reported in 2005:

The most distinguishing characteristic of the epidemiology of TB disease in Minnesota is the very large proportion of TB cases reported among foreign-born persons, which has averaged 81% over the past 5 years. In 2005, 173 (87%) new TB cases in Minnesota occurred in persons born outside the United States. This exceptionally high percentage of foreign-born TB cases reported in 2005 represents the largest proportion of foreign-born cases reported in Minnesota since 1992, when MDH began collecting data on TB case-patients’ countries of birth. In contrast, 54% of TB cases reported nationwide in 2005 were foreign-born.

The 173 foreign-born TB case-patients reported in Minnesota during 2005 represent 31 different countries of birth. The most common region of birth among foreign-born TB cases reported in 2005 was sub-Saharan Africa (58%), followed by South/Southeast Asia (24%)

In a 2009 article published in Bildhaan: An International Journal of Somali Studies, author Amin Mohamed wrote:

Minnesota’s foreign-born population has increased significantly as refugees around the world are choosing to reside in the state. According to the Center for Immigration Studies report in December 2005, Minnesota’s immigrant population increased from 261,000 in 2000 to 374,000 in 2005 (a 43.3% increase).

The state also has one of the highest percentages of tuberculosis cases among foreign-born residents in the United States. The percentage of foreign-born persons’ TB cases in Minnesota increased from 50% in 1995 to 87% in 2005.

…

Among the foreign-born patients in Minnesota from 2001 through 2005, the largest percentage (34%) was born in Somalia.

Though the foreign-born TB problem in Minnesota began around 1990, MDH did not begin publicly reporting LTBI rates among arriving refugees until 2004.

An additional reason cited by the 2013 University of California at San Diego study for the risk of active TB posed by high rates of latent TB infection within the refugee community is the very low rates of completion of latent TB treatment programs among that group.

The problem is particularly severe among refugees arriving from Sub-Saharan Africa, the study reports:

In this study of LTBI prevalence based on interferon γ release assays and LTBI treatment among refugees resettling in San Diego County between 2010 and 2012, refugees from sub-Saharan Africa had the highest prevalence of LTBI (43.1%) compared with refugees from the Middle East (18.3%) and Asia (19.0%). Despite the significantly higher odds of LTBI among refugees from sub-Saharan Africa, LTBI treatment initiation was significantly lower among these refugees than among refugees from the Middle East (60.5% and 78.6%, respectively; P ≤ .001). This is concerning because it reveals a missed opportunity to decrease the risk of progression to active TB among this high-risk group of refugees resettling in the United States. Treatment completion analysis was limited by small numbers but suggested that refugees from sub-Saharan Africa may also have lower treatment completion rates than refugees from the Middle East (71.4% and 86.2%, respectively; P = .51), although this was not statistically significant.

…

The low treatment initiation among refugees from sub-Saharan Africa in this study is particularly alarming because refugees from this region of the world have been resettling in the United States since 1980. Although there is likely no single factor that accounts for the low treatment rates among this group of refugees, future research using focus groups among African refugees with LTBI could help understand the reasons for this disparity.

MDH says that the treatment completion rate among all refugees has improved in recent years.

The Minnesota Refugee Health Report for 2011 published by MDH reported that 90 percent of the 610 refugees who arrived in 2010, or 548, in need of LTBI therapy were placed on such therapy.

Of those, 82 percent, or 451 out of 548, completed latent TB infection therapy. All told, 152 refugees who arrived in Minnesota in 2010 who tested positive for LTBI, however, received no treatment.

The percentage of refugees who tested positive for LTBI and successfully completed latent TB infection therapy after being placed on it increased to 86 percent in 2014.

Prior to 2010, however, the percentage of refugees who tested positive for LTBI who successfully completed therapy was apparently much lower. The objective for 2011 was only 55 percent, indicating that was a goal above what had been accomplished in the previous years.

That suggests a fairly large population of refugees who arrived in the six year period between 2004 and 2009 for which we have data were never treated for LTBI and remain at risk for activation.

A total of 8,056 refugees tested positive for LTBI in Minnesota during those six years.

Assuming 90 percent of those initiated LTBI therapy, and 50 percent of those completed LTBI therapy, as many as 4,431 refugees who arrived in Minnesota between 2004 and 2009 have LTBI and remain at risk for developing active TB.

Added to that are decades of refugees who arrived before Minnesota began reporting this data in 2004.

In its statement to Breitbart News, MDH admitted:

The data you are referring to, showing 50% of the 593 foreign born residents of Minnesota diagnosed with TB arrived as refugees, represents years 2010 – 2014. The majority of those refugees actually developed TB disease after being in Minnesota at least five years, and many had been in the US at least 10 years, so these are not new arrivals to the US.

In other words, the majority of the 296 refugees diagnosed with active TB in Minnesota between 2010 and 2014 arrived in Minnesota prior to 2009, during the period when the state experienced very high rates of LTBI among arriving refugees, combined with much lower treatment rates for those refugees.

Presumably, many of those refugees with LTBI still reside in Minnesota.

Here’s a summary of LTBI infection rates among refugees arriving in Minnesota between 2004 and 2014, as provided by MDH:

In 2004, 34 percent of arriving refugees tested positive for LTBI in Minnesota. Fifty-five percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2005, 40 percent of arriving refugees tested positive for LTBI in Minnesota. Fifty-one percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2006, 46 percent of arriving refugees tested positive for LTBI in Minnesota. Forty-nine percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2007, 45 percent of arriving refugees tested positive for LTBI in Minnesota. Fifty percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2008, 30 percent of arriving refugees tested positive for LTBI in Minnesota. Forty-five percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2009, 30 percent of arriving refugees tested positive for LTBI in Minnesota. Forty-two percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2010, 28 percent of arriving refugees tested positive for LTBI in Minnesota. Forty percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2011, 22 percent of arriving refugees tested positive for LTBI in Minnesota. Thirty-six percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2012, 22 percent of arriving refugees tested positive for LTBI in Minnesota. Thirty percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2013, 22 percent of arriving refugees tested positive for LTBI in Minnesota. Thirty percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In 2014, 22 percent of arriving refugees tested positive for LTBI in Minnesota. Thirty percent of refugees arriving in Minnesota whose country of origin was in Sub-Saharan Africa tested positive for LTBI.

In a 2015 study, several researchers at the Centers for Disease Control recommended that “implementing LTBI [latent tuberculosis infection] screening and treatment for United States bound refugees from countries with high or moderate LTBI prevalence would potentially save millions of dollars and contribute to United States TB elimination goals.”

“These estimates are conservative since secondary transmission from tuberculosis cases in the United States was not considered in the model,” the authors note.