Epidemiology

The Trichinella genus includes eight species and three genotypes (Table 1),[2,3] which can only be distinguished through biochemical or molecular analysis.[4]

Both a sylvatic and a domestic cycle of Trichinella have been documented.[2,5,6] The sylvatic cycle has been observed for all Trichinella species, and it is maintained in nature by animals with cannibalistic and scavenger behavior (Table 1), although omnivores (e.g., wild boar) can also act as a reservoir. Human infections related to the sylvatic cycle are mainly caused by the consumption of game meat (e.g., bear, walrus, fox, cougar, wild boar, and warthog).[5] The domestic cycle is only established as a result of improper practices in animal rearing, mainly pig rearing[2] (e.g., the use of raw or uncontrolled pig scraps or the carcasses of sylvatic carnivores as food for pigs). In nearly all cases, the domestic cycle has involved Trichinella spiralis, although in particular epidemiolog-ical situations, Trichinella britovi and Trichinella pseu-dospiralis have also been transmitted between pigs and from pigs to humans.[2,6] A high prevalence of Trichinella infection in pigs has also been shown to be associated with the transmission to unusual hosts, such as herbivores. For example, in France and Italy, about 3500 human infections were caused by the consumption of raw horse meat imported from countries with a high prevalence of T. spiralis infection in pigs.[2] In China, where the prevalence of Trichinella infection in pigs is very high, hundreds of human infections were attributed to the consumption of mutton.[2] Whether or not rodents constitute a reservoir of T. spiralis in the domestic cycle has been a topic of debate, especially with regard to rats, although it is more likely that these animals act as a vector of Trichinella infection, as opposed to a reservoir.[2,6]

The countries reported to have the highest prevalence of trichinellosis in humans are Argentina, Byelorussia, Bulgaria, Chile, China, Croatia, Georgia, Latvia, Lithuania, Malaysia, Mexico, Moldova, Myanmar, Romania, Russia, Serbia, Thailand, and Ukraine. In the European Union, in the past 25 years, more than 6800 human infections, 5 of which resulted in death, have been documented, with the cause of infection reported to be the consumption of horse meat, pork, and game meat.[5] In the United States, in the past 10 years, about 40 human infections per year have been reported, including some deaths.[5] In Canada, about 20 persons per year acquire infection for the consumption of game meat, prevalently walrus meat consumed by Inuit populations in the Arctic.[5] A few human infections have also been documented in Africa (i.e., Ethiopia, Kenya, Senegal, and Tanzania) and in the Australian Region (New Zealand and Papua New Guinea).[2]

Table 1 Geographical distribution, hosts, and main biological and clinical features of Trichinella species and genotypes

Species Geographical distribution Cycle Hosts Biological features Clinical features

Table 1 Geographical distribution, hosts, and main biological and clinical features of Trichinella species and genotypes

Species Geographical distribution Cycle Hosts Biological features Clinical features

T. spiralis

Cosmopolitan

Domestic

Pig, wild boar,

Encapsulated; no resistance

Highly pathogenic;

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Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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