Human-to-Cattle Mycobacterium tuberculosis Complex Transmission in the United States

Abstract

The Mycobacterium tuberculosis complex (MTBC) species includes both M. tuberculosis, the primary cause of human tuberculosis (TB), and M. bovis, the primary cause of bovine tuberculosis (bTB), as well as other closely related Mycobacterium species. Zoonotic transmission of M. bovis from cattle to humans was recognized more than a century ago, but transmission of MTBC species from humans to cattle is less often recognized. Within the last decade, multiple published reports from around the world describe human-to-cattle transmission of MTBC. Three probable cases of human-to-cattle MTBC transmission have occurred in the United States since 2013. In the first case, detection of active TB disease (M. bovis) in a dairy employee in North Dakota prompted testing and ultimate detection of bTB infection in the dairy herd. Whole genome sequencing (WGS) demonstrated a match between the bTB strain in the employee and an infected cow. North Dakota animal and public health officials concluded that the employee's infection was the most likely source of disease introduction in the dairy. The second case involved a Wisconsin dairy herd with an employee diagnosed with TB disease in 2015. Subsequently, the herd was tested twice with no disease detected. Three years later, a cow originating from this herd was detected with bTB at slaughter. The strain in the slaughter case matched that of the past employee based on WGS. The third case was a 4-month-old heifer calf born in New Mexico and transported to Texas. The calf was TB tested per Texas entry requirements and found to have M. tuberculosis. Humans are the suspected source of M. tuberculosis in cattle; however, public health authorities were not able to identify an infected human associated with the cattle operation. These three cases provide strong evidence of human-to-cattle transmission of MTBC organisms and highlight human infection as a potential source of introduction of MTBC into dairy herds in the United States. To better understand and address the issue, a multisectoral One Health approach is needed, where industry, public health, and animal health work together to better understand the epidemiology and identify preventive measures to protect human and animal health.

Mycobacterium bovis Transmission between Cattle and a Farmer in Central Poland

“…Other symptoms might occur depending on the part of the body affected by the disease [ 34 ]. In the course of tuberculosis in the described case, the man experienced night sweats, fever, and cough, which are the same as those in the case described by Lombard et al [ 35 ]. The subject of this research was a man who worked in a dairy from January to March 2015 in the USA.…”

Factors associated with zoonosis and reverse zoonosis of mycobacterium tuberculosis and mycobacterium bovis in Ethiopia

“…Reverse zoonosis caused by Mycobacterium TB has been linked to the male gender, with an odds ratio of (OR 4.89; 95% CI: 1.79-9.36). This involvement could be attributed to infected males urinating on livestock feed, which is then ingested by cattle (Lombard et al, 2021). Furthermore, tobacco chewing and injecting into cattle's mouths is a uniquely Ethiopian cultural habit, performed almost exclusively by male Ethiopian farmers.…”

Zoonotic Tuberculosis: A Neglected Disease in the Middle East and North Africa (MENA) Region

“…Furthermore, uncontrolled animal migrations and trade within and across countries were noted as key drivers for BTB transmission [ 26 ]. People working closely with livestock, particularly dairy cattle (e.g., farmers, veterinarians, slaughterhouse workers) or with wildlife were more susceptible to M. bovis infections [ 27 ].…”