Identify the incorrect organism combination.

The combination involving Balantidium coli as being common within the United States is deemed incorrect because, while Balantidium coli is the only ciliated protozoan known to infect humans and is associated with balantidiasis, its prevalence in the U.S. is relatively low. The organism is more commonly linked to areas with poor sanitary conditions and is often found in developing countries or regions where there is a higher prevalence of pigs, which are a primary reservoir for the parasite. In contrast, the first three options represent valid associations: Strongyloides stercoralis can cause internal autoinfection, Echinococcus granulosus is correctly linked with hydatid examinations in relation to its life cycle and pathology, and serological tests are indeed utilized for diagnosing Toxoplasma infections. Thus, the assertion regarding Balantidium coli does not reflect the current epidemiological data and typical occurrence in the United States.