Tuberculosis (TB) continues to be a significant problem and a major cause of morbidity and mortality in the developing world despite decades of intensive efforts to combat the disease. The poverty in these endemic areas is associated with an increased incidence of tropical helminthic infections. The purpose of this review is to bring to the fore, the urgent need to unravel the potential consequences of helminth coinfection to tuberculosis disease pathogenesis and transmission.
There is now strong experimental evidence that helminth-induced T helper (Th)2 and T regulatory (Treg) responses impinge on host resistance against Mycobacterium tuberculosis (Mtb) infection. Several studies show that Th1 response is reduced in helminth coinfected hosts. Emerging studies also indicate that helminth-induced alternatively activated macrophages contribute to enhanced susceptibility to TB. Despite studies showing an association between helminthes and diminished Th1 immunity, maternal antihelminthic treatment had no effect on an infant's response to bacille Calmette-Guerin vaccination.
Whether helminthes affect tuberculosis (TB) disease is still an open question and clinical trials are warranted to determine at the population level whether helminthes enhance TB incidence and transmission and diminish the protective immune response to vaccines. Consequently, mass deworming of infected individuals could contribute toward overall improvement of global public health.
aDepartment of Medicine, Centre for Emerging Pathogens, UMDNJ-New Jersey Medical School, Newark, New Jersey, USA
bNúcleo de Doenças Infecciosas, Universidade Federal do Espírito Santo – UFES
cSection of Infectious Diseases, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts, USA
Correspondence to Jerrold J. Ellner, Section of Infectious Diseases, Boston Medical Centre, Boston, MA 02118, USA. Tel: +1 617 414 3510; e-mail: Jerrold.Ellner@bmc.org