Taenia solium cysticercosis of humans and pigs: a review of our contributions and perspectives in the research of its complexities

This is a brief account of some of the problems posed by Taenia solium cysticercosis that we have approached since the early 70's and a summary of our principal results and/or present position about each of them. In Human neurocysticercosis (NC): NC is a clinically pleomorphic disease in symptoms and severity that range from clinical silence to life threatening and sometimes deadly conditions. The rural population of Mexico shows higher NC prevalence (aprox 10%) than is generally recognized, but most of the cases are clinically silent. Serologic diagnosis is still unsatisfactory but immunodiagnosis in CSF of symptomatic NC performs somewhat better. The use of synthetic peptides derived from recombinant antigens open a new possibility to improve diagnosis. 90% of people with positive serology in Mexico do not cluster around the household, which speaks of far reaching mechanisms of transmission that operate in highly endemic situations in addition to the importance of living in close proximity with tapeworm carriers that operates in both high and low endemic situations. There are hints that severity associates with inflammation, gender and genetic background of the human host but not with level of exposure to infection. There are also indications that the TH1/TH2 balance of the immune response may be decisive for the outcome of an infection. In Pig-cysticercosis (PC): PC prevalence is alarmingly high (5 to 30%) in rural villages of Mexico. A synthetic peptide vaccine against PC was shown to reduce 50% the prevalence and 98% the intensity of PC in a realistic field trial of pigs exposed for one year to natural infection, enticing its application as an adjunct in transmission control. Antipeptide antibodies of vaccinated pigs cripple the ability of cysticerci to develop unto adult tapeworm parasites, a subtle yet important and applicable effect of antibodies otherwise considered inoperative. Castration and pregnancy of pigs double their expected prevalence from about 25 to 50%, an indication of hormonal involvement in susceptibility to infection. Experimental infections hint to genetic factors in controlling parasite establishment. In Taenia solium: Cysticerci collected from different donor pigs naturally infected in different geographic areas of Mexico show substantial antigenic diversity peaking out of a comparatively highly similar DNA background, an indication that the expression of antigens may be subject to circumstantial factors of the parasite, the host and/or the environment.