Human Trichinellosis From Laos

Abstract

There are biblical references to an illness that could have been trichinellosis and which was associated with consumption of pork, but the nematode Trichinella spiralis was first described in 1835. The genus Trichenella contains at least seven species: T spiralis , Trichenella nativa , Trichenella britovi , Trichenella pseudospiralis , Trichenella murrelli , Trichenella nelsoni , and Trichenella papuae. 1 The geographical distribution of the different species is related to ecology, climate, and host behavior.2 The host range of Trichinella is wider than previously believed. New species are being continuously recognized. Three classes of vertebrates are known to act as hosts (ie, mammals, birds, and reptiles). Mammals represent the most important hosts, and all Trichinella species are able to develop in this class. The nonencapsulated species T pseudospiralis , detected in both mammals and birds, show a cosmopolitan distribution. They tend to have a more prolonged clinical course. Three cases of trichinellosis, after a saltwater turtle dinner, were reported from Songkhla, Thailand, 14 years ago. The species of the turtle and of the Trichinella were not identified. Two additional nonencapsulated species, T papuae , detected in wild pigs and saltwater crocodiles of Papua, New Guinea, and Trichenella zimbabwensis , found in farmed Nile crocodiles and in sylvatic monitor lizards of Zimbabwe, have been reported.3,4 The life cycle of Trichinella is completed when first‐stage larvae mature in striated muscle. Such larvae are immunogenic, as evidenced by sustained antibody production against larval glycans. In contrast to a vigorous systemic immune response, local inflammation is limited. Nonencapsulating species of Trichinella such as T pseudospiralis induce little to no local inflammatory responses in reptilian, avian, and mammalian hosts. They also appear to remain viable longer. Encapsulated species induce limited local inflammation in a variety of mammalian hosts, which contributes to isolation and …