Figure 1. Mechanism of immune modulation caused by helminth infections affecting immune responses and susceptibility to TB.

Exposure to helminth infection occurs early in areas of endemicity, with early mixed Th1/Th2 responses eventually leading to expansion of Th2 and Treg responses with establishment of chronic infection. This in turn can alter the phenotype and functionality of antigen-presenting cells as shown. The immune skewing that occurs as a result alters immune responses to Mtb and might affect susceptibility to TB. In utero sensitization to helminth antigens that leads to a similar skewing of the neonatal immune system can occur and thereby alter the immunogenicity of Mtb-specific vaccines.