In this review, we describe the current knowledge on the systematics, ecology and epidemiology of Trichinella and trichinellosis, and the impact of recent research discoveries on the understanding of this zoonosis The epidemiology of this zoonosis has experienced important changes over the past two decades, especially with regard to the importance of the sylvatic cycle and the sylvatic species Outbreaks of trichinellosis due to Trichinella spiralis from domestic swine, while still frequent, increasingly are caused by other Trichinella spp infecting hosts such as horses, dogs, wild boars, bears and walruses The latter revelations have occurred as a result of a series of discoveries on the systematics of Trichinella spp, facilitated by new molecular tools As a consequence, the genus is now composed of two clades, an encapsulated group (five species and three genotypes) and a non-encapsulated one (three species) This has sparked renewed investigations on the host range of these parasites and their epidemiological features Most dramatic, perhaps, is the recognition that reptiles may also serve as hosts for certain species This new knowledge base, in addition to having an important relevance for food safety policies and protection measures, is raising important questions on the phylogeny of Trichinella spp, the ecological characteristics of the species and their geographic histories Answers to these questions may have great value for the understanding of the evolutionary biology for other parasitic helminths, and may increase the value of this genus as models for research on parasitism in general

Systematics and epidemiology of trichinella.

Genetic characterization and phylogenetic position of Echinococcus felidis (Cestoda: Taeniidae) from the African lion.

hyperoxia greatly reduces the incidence of phenytoin-induced cleft lip and palate in A/J mice. Science 212: 671–672 10. Moerman P, Fryns J P, Goddeeris P, Lauweryns J M, van Assche A 1983 Aberrant twinning (diprosopus) associated with anencephaly. Clinical Genetics 24: 252–256 11. Ramadan R O 1996 A dicephalic goat with other defects. Zentralblatt fur Veterinarmedizin Reihe A 43: 337–343 12. Saini S S, Khehra R S, Kwatra M S 1993 A diprosopus in a domestic chicken embryo. Avian Diseases 37: 898–899 13. Tiessen R G, van Elsacker-Niele A M, Vermeij-Keers C, Oepkes D, van Roosmalen J, Gorsira M C 1994 A fetus with a parvovirus B19 infection and congenital anomalies. Prenatal Diagnosis 14: 173–176 14. Verdi G D, Hersh J H, Russell L J 1991 Partial duplication of the face: case report and review. Plastic and Reconstructive Surgery 87: 759–762 15. Wei X, Sulik K K 1993 Pathogenesis of craniofacial and body wall malformations induced by ochratoxin A in mice. American Journal of Medical Genetics 47: 862–871 16. Yoneda T, Pratt R M 1982 Vitamin B6 reduces cortisone-induced cleft palate in the mouse. Teratology 26: 255–258

http://jsava.co.za/index.php/jsava/article/download/343/330

WHO/FAO/OIE guidelines for the surveillance, prevention and control of taeniosis/cysticercosis

Lymphatic filariasis: new insights into an old disease

Publisher Summary This chapter summarizes all significant matters concerning Taenia saginata (T. saginata) taeniasis and cysticercosis—that is, nomenclature, host relationships, structure and biology, clinical and therapeutic features, epidemiology and epizootiology, and prevention of infection. It considers some taxonomic problems and the hosts of T. saginata. The structure and biology of the adult worm, egg, onchosphere, and cysticercus is discussed. The clinical aspects of taeniasis are dealt in terms of symptomatology, clinical pathology, diagnosis, and treatment. Yomesan is the drug of choice for T. saginata infection in Man at present, and some suggestions are made for treatment with this and other drugs. The chapter discusses epidemiology, epizootiological, and losses due to taeniasis and cysticercosis. Losses are difficult to estimate, because infection is rarely fatal, but some figures are available for European, African, and American areas. Meat inspection is dealt with as a means of prevention, likewise serological diagnosis and the immunization of cattle. Sanitation is a matter discussed, its improvement, expensive but connected with higher standards of living.

Taeniasis and cysticercosis (Taenia saginata).

A glass chamber method of counting living microfilariae in 20–100 c.mm. samples of freshly haemolyzed blood proved to be substantially more sensitive than, and as reliable as, the use of standard wet or stained dry films. The method has the further advantages of simplicity and brevity. The results showed that with the “normal” thick smear technique between 30 and 40% of microfilariae are lost during processing of the slide. It is suggested that the chamber counting method has practical field and laboratory utility.

Comparison of a counting chamber and thick smear methods of counting microfilariae

The significance of wild animals in the transmission of cestodes of medical importance in Kenya.

Comparative studies on geographical strains of Trichinella spiralis.

Previous studies have shown that when cattle are exposed to cercariae of Schistosoma mansoni they develop considerable resistance to subsequent challenge with S. mattheei. The present study showed that when sheep are immunized with S. mansoni cercariae they too develop a marked resistance to subsequent challenge with S. mattheei. A small proportion of the immunizing cercariae reached maturity and a few viable S. mansoni eggs were found in the faeces of the sheep. The results of this experiment provide further evidence that heterologous immunity may be of significance in limiting the severity of schistosomiasis in both man and domestic animals in areas where animal and human schistosomes occur together.

Studies on heterologous immunity in schistosomiasis: 4. Heterologous schistosome immunity in cattle

1. 1) In this preliminary note the results are given of the examination of 537 animals from the area in Kenya where Forrester et al. (1961) described an outbreak of human trichinosis. 2. 2) T. spiralis larvae were found in a dog (Canis familiaris) and a leopard (Felis pardus) collected near Kerugoya on the lower slopes of Mount Kenya. The dog had eaten part of a wild pig (Potamochoerus porcus) which was believed to be the source of the human infections. It is known that leopards also eat wild pigs. 3. 3) Four hundred and thirty-seven rodents and more than 50 carnivores which are known to eat rodents were examined; none was infected. 4. 4) T. spiralis larvae were found in a hyaena (Crocuta crocuta) from the Masai plains more than 100 miles from Kerugoya. 5. 5) Trichinosis is believed to be rare in the tropics. There are no previous records of infections in wild animals in Africa. Man probably contracts trichinosis in Africa when he intrudes into a cycle confined to wild animals. The incidence and distribution of the infection in animals is not yet known.

G.S. Nelson

Papers

Comparison of a counting chamber and thick smear methods of counting microfilariae

The significance of wild animals in the transmission of cestodes of medical importance in Kenya.

Comparative studies on geographical strains of Trichinella spiralis.

Studies on heterologous immunity in schistosomiasis: 4. Heterologous schistosome immunity in cattle

Feral trichinosis in Africa