Contributions to natural sources and methods of transmission of Gnathostoma spinigerum in Thailand
Daengsvang, S.
Southeast Asian Journal of Tropical Medicine and Public Health 1: 95-101
1976
ISSN/ISBN: 0125-1562 PMID: 1027116 Document Number: 103507
There are 43 spp. of vertebrates [fresh-water fish, frog, snake, monitor lizard, chicken, duck, bird, rat, mongoose, tree shrew] naturally infected with varying numbers of G. spinigerum advanced 3rd-stage larvae in any one host. They are the natural sources of the infection for the definitive host and man. More species of vertebrates and some invertebrates might harbor the larvae. Crabs are potential transmitting (paratenic) hosts of the worm. Some of the larvae in infected hosts may remain alive in the cyst wall and infective for at least 3 yr. Man could acquire an infection by ingestion of fully developed larvae in cyclops. Nonhuman primates and man may be infected by drinking contaminated water containing both stages, fully developed larvae in cyclops and the advanced 3rd-stage larvae after being removed from the infected hosts and placed in fresh water, because of the long period of infectivity. The definitive host would be infected only by drinking contaminated water containing the living advanced 3rd-stage larvae. Only the active advanced 3rd-stage larvae obtained from the infected host naturally penetrate through the intact skin of the definitive host and man, but not the fully developed larvae from cyclops. A natural method of transmission of the advanced 3rd-stage larvae may be expected in an infected pregnant definitive host or a pregnant woman. These natural sources of infection and experimental methods of transmission of G. spinigerum discovered in animals have provided knowledge for effective preventive measures against human and animal gnathostomiasis.