A phylogenetic hypothesis for the distribution of two genotypes of the pig tapeworm Taenia solium worldwide

M.  NAKAO  a1 , M.  OKAMOTO  a2 , Y.  SAKO  a1 , H.  YAMASAKI  a1 , K.  NAKAYA  a3 and A.  ITO  a1 c1
a1 Department of Parasitology, Asahikawa Medical College, Asahikawa, Japan
a2 Department of Laboratory Animal Science, School of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
a3 Animal Laboratory for Medical Research, Asahikawa Medical College, Asahikawa, Japan

Article author query
nakao m   [PubMed][Google Scholar] 
okamoto m   [PubMed][Google Scholar] 
sako y   [PubMed][Google Scholar] 
yamasaki h   [PubMed][Google Scholar] 
nakaya k   [PubMed][Google Scholar] 
ito a   [PubMed][Google Scholar] 


Genetic polymorphism was determined among 13 isolates of Taenia solium from various regions using PCR-amplified sequences of 2 mitochondrial genes: cytochrome c oxidase subunit 1 and cytochrome b. The 2 phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia (China, Thailand, Irian Jaya and India) formed a single cluster, whereas the isolates from Latin America (Mexico, Peru, Ecuador, Bolivia and Brazil) combined with those from Africa (Tanzania, Mozambique and Cameroon) to form an additional cluster. These results and historical data of swine domestication, distribution of pigs and colonization suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that the tapeworm of another origin independently spread in Asian countries.

(Received December 27 2001)
(Revised January 24 2002)
(Accepted January 24 2002)

Key Words: Taenia solium; distribution; phylogeny; DNA polymorphism.

c1 Corresponding author: Department of Parasitology, Asahikawa Medical College, Midorigaoka-Higashi 2-1-1-1, Asahikawa, Hokkaido 078-8510, Japan. Tel: +81 166 68 2420. Fax: +81 166 68 2429. E-mail: