The distribution of Trichinella spiralis larvae in the muscles of primates

Nowadays the examination of pig carcases for trichinellae by the use of Reissmann's method is the only legalized way of postmortem diagnosis of trichinellosis. Having in mind the need to find a procedure to obtain results of trichinoscopical examinations before the removal of the pigs head and viscera, N. E. Kosminkov undertook in 1954 comparative studies on 29 pigs infected with trichinellae on the intensity and extensity of the infestation in the muscles of the ears, tonque, neck, tail, fore legs, larynx, oesophagus and the mastication muscles with the view to establish which of these muscles are invaded as frequently as the crura diaphragmatica. The author demonstrated that as regards the incidence of infestation the crura diaphragmatica occupy the first place and are followed by the muscles of the oesophagus, tongue, neck, masseters, toes, ears and tail. As far as the intensity of the infestation is concerned the first place is occupied also by the crura diaphragmatica, followed by the tongue, oesophagus, ears, neck, toes, masseters and tail. On the basis of these data Kosminkov recommends that the oesophagus should be examined for trichinellosis instead of the crura diaphragmatica, despite the fact that the tongue is more intensively infested than the oesophagus (1.5:1). According to Dyakonov's (1939) comparative studies, conducted on 22 trichinous pigs on the extensity and intensity of infestation of the crura diaphragmatica, pars costalis, tongue, masseter, pharynx and the oesophagus, foremost in the incidence of infestation are the crura diaphragmatica, followed by pars costalis. tongue, pharynx and oesophagus, the tongue being 4.5 times more strongly invaded than the oesophagus. On the basis of the results obtained by Dyakonov and in the course of Kosminkov's investigations, according to whom the tongue. as far as the intensity of the infestation is concerned, follows in this respect the diaphragm and has a higher incidence than the oesophagus (1.5:1). Matoff (1960) is of the opinion that one should be careful in raking higher the oesophagus than the tongue in the examinations for trichinellosis. Matoff (1960) draws attention to the fact that the difference between the incidence of invasion of the crura diaphragmatica and other muscles of predilection is most markedly manifrsted in pigs with a mild infestation in the trichinoscopy of a standard number of preparations and that the trichinellae demonstrated in pigs affected with a mild infestation by the standard method is a matter of hazard, as has been established by Veelken (1913), Prost (1960) and earlier by Virchow (1864), Reissmann (1908) and others. In the case of pigs affected with very mild infestation the examination of the standard number of preparations obtained from the oesophagus under the existing sharp difference in the intensity of infestation between the crura diaphragmatica and the oesophagus (nearly eight times according to Dyakonov and two times according to Kosminkov no trichinellae may be found in the muscles). In conclusion Matoff stresses that the intensity of infestation of the various muscles is the feature of the greatest importance as regards the possibility of diagnosis of trichinellosis in slaughter houses. With the exception of Koryazhnov (1955), Kosminkov's suggestion has been supported by three other Soviet investigators: Merkoushev (1960), Portalimov (1960) and Mihnyuk (1960). Detailed investigations have been undertaken for the final elucidation of the problem of the infestation of muscles with trichinellae, the various types of muscles in 16 experimental pigs were examined. The results obtained are at variance with the claims of Merkoushev, Mihnyuk and Portalimow and their favourable attitude towards Kosminkov's recommendation for the examination of the oesophagus instead of the crura diaphragmatica and provide new proofs in favour of Matoff's (1960) opinion, expressed earlier. Investigatory data obtained by the use of the compressor method and 1 g. samples of 17 kinds of muscles show, as far as the intensity of infestation is concerned, the muscles can be arranged in the following order: the crura diaphragmatica, tongue, pars costalis, neck, masseters, pharynx, intercostal muscles, oesophagus, abdominal muscles etc. It shows that the tongue is second in order after the crura diaphragmatica, whereas the oesophagus occupies the eighth place. The ratio of infestation with trichinellae between the crura diaphragmatica and the tongue was 1.2:1 and that between the crura diaphragmatica and the oesophagus 3.7:1, between the tongue and the oesophagus 3.09;1. The generally accepted opinion is that the more massive invasion the difference in intensity between the separate kinds of muscles efface. Exact and careful count of trichinellae per 1 g. of each muscle studied has shown that the difference is preserved also in pigs of heavy infestation and that the tongue is affected with a much higher intrnsity of infestation than the oesophagus. On the basis of the present results the opinion is expressed that in the slaughter houses where it is necessary to supply the data of the examination for trichinellae prior to the dividing of the carcases and prior to the removal of the internal organs, it is the tongue and not the oesophagus that may replace the crura diaphragmatica. The important epidemiological and epizootiological problem of the risk taken in diagnosis is also analysed in cases where the tongue instead of the crura diaphragmatica is examined by trichinoscopy. On the basis of the results obtained by Veelken, Kosminkov and Prost, who have examined chiefly the crura diaphragmatica of weakly infested pigs it should be assumed that failures to prove the presence of trichinellae are possible also in the course of the examination of the tongue by the standard trichinoscopy method. The investigations conducted by Scahwartz (1940a, 1940b and 1960) and Prost (1961) provide sufficient data which show that when employing the standard method of trichinoscopy, as opposed to the artificial d'gestion method, no considerable number of trichinellae are found in pigs affected with trichinellosis and that slightly trithinous carcases are likely to be released for human consumption. Accordlng to Veelken, Gunther, Bongest, Kalyus and other workers, the inevitable omission of weakly infested pigs in slaughter houses presents no danger for the consumer, since the trichinellae are found in the diaphragrri only, whereas there were either no trichinellae or only single spacimens in other muscles. In the opinion of Matoff (1956, 1961), in a very mild infestation there are in fact no such cases where muscle trichinellae are found but in the crura diaphragmatica, while there are none in the skeletal muscles. The young trichinellae migrating via the blood stream, spread throughout all striated muscles, though unevenly, both among muscles and in each muscle, and their detection in muscles of weak infestation - with the exception of the crura diaphragmatica - is a matter of the examination of a larger number of preparations. Matoff and Vaptsarova (1937) have found as the result of examinations of the whole musculature (divided into 14 groups) of 7 mice infested with 2 muscle trichinellae each, that all muscle groups were affected with trichinellae and that the ratio between the number of the muscle trichinellae in the diaphragm and the total number of trichinellae in the remaining muscles was 1:10. Chance and inevitable omission of weakly trichinous meat under competent trichinella inspection carried out carefully is not dangerous for man, because (1) according to the data in the literature all cases of trichinellosis occur as the result of ingestion of strongly or medium infested pork and not weakly infested, and (2) because single trichinellae may cause only a latent and symptomfree invasion. If, on one hand, the possible omission in slaughter houses routine practice of pig carcases weakly infested with trichinellae conceal no danger to man, on the other hand, could be the source of a trichinellae spreading (kitchen and slaughter house offals) among pigs, dogs, cats. The danger in these cases, however, is lesser than in the case where no trichnoscopic examination has been conducted. In conclusion the authors believe that the standard method of examination using trichinoscopy, which at present is generally accepted and widespread, despite certain arguments against it and the fact thak weak invasions may remain undetected, is for the time being the sole most reliable method for detection of trichinellosis, as proved by slaughter houses statistics, particularly in Germany (Schonberg, 1956)

dal'nejjshie issledovanija problemy myshechnykh trikhinell vystupajushhikh v organakh lishennykh polosatykh myshc

The present paper sets forth the negative results obtained by the authors from further investigation by the digestive and biological methods of the viscera of 15 experimental trichinellized pigs for the presence of muscle trichinae. On the basis of the results of these investigations and the results of their earlier studies, undertaken with the aim of checking the veracity of Hill's findings of muscle trichinae in viscera of trichinous swine, the authours make an analysis of Lukashenko's findings of muscle trichinae in viscera of trichinous swine, cats, rabbits, guinea-pigs and rats and the findings by Ketz in the cardiac muscle and the kidneys of trichinous hamsters. Contrary to Lukashenko and Keiz, the authors confirm their initial standpoint (1963) that no muscle trichinae develop and are encountered in viscera devoid of striated muscle fibres of swine and other animals.Jest to dalsza seria ujemnych wyników, uzyskanych metodami wytrawiania i biologiczną, w poszukiwaniu włośni mięśniowych w narządach trzewiowych 15 doświadczalnie zarażonych świń. W oparciu o te wyniki i rezultaty poprzedniej pracy, podjętej dla potwierdzenia danych Hilla, który spotkał larwy pasożyta w trzewiach zarażonych świń, autorzy poddali analizie wyniki Łukaszenki. który także znajdował larwy w narządach świń, kotów, królików, świnek morskich i szczurów, oraz dane Ketza, opisującego włośnie w mięśniu serca i w nerkach zarażonych chomików. Wbrew danym Łukaszenki i Ketza autorzy tej pracy potwierdzają swój wcześniejszy pogląd (1963), że larwy mięśniowe nie rozwijają się ani też nie występują w narządach trzewiowych pozbawionych włókien mięśni prążkowanych świń lub innych zwierząt