Angiostrongylus infections in rats and snails in northeast Thailand.

A survey of Angiostrongylus infections in rats and snails was carried out in the provinces of Ubon Ratchathani, Udon Thani. Kalasin, Chaiyaphum and Khon Kaen in northeast Thailand. Only two Rattus norvegicus (3.8%) and one Bandicota indica (1.4%) out of 151 R. rattus, 52 R. norvegicus and 69 B. indica examined were infected with adult lung worms. All worms recovered were A. cantonensis. Prevalence of infection in 423 Pila polita was 0.9% while all of 77 P. ampullacea were negative for larvae. In contrast to this 36.4% of 500 Achatina fulica harbored L3 of Angiostrongylus (with variations of between 29% and 46% in the five provinces). The average infection intensity in A. fulica was 13.6 L3 (1 to 441). Experimental infection of Wistar rats with L3 (isolated from A. fulica resulted in a recovery rate of 48.3% of adult worms of which 91.7% and 8.3% were identified as A. cantonensis and A. malaysiensis, respectively. This is the first proven finding of A. malaysiensis in northeast Thailand.

Studies on lophocercous cercariae from Bithynia siamensis goniomphalus (Prosobranchia: Bithyniidae).

Cercariae from Bithynia siamensis goniomphalus were studied in an area endemic for opisthorchiasis. Snails emitted different types of cercariae when shedding was induced by illumination. In addition to two lophocercous cercariae, a monostome cercaria (probably Notocotylus sp), two different furcocercariae and a xiphidiocercaria were found. Two similar types of lophocercous cercariae were distinguishable and one could be identified as Opisthorchis viverrini. To date the cercaria of O. viverrini has been regarded as the only lophocercous cercaria in the endemic area of opisthorchiasis. Therefore, differences between these cercariae were further characterized by scanning electron microscopy to enable us to avoid misinterpretations of O. viverrini in Bithynia.

Studies on metacercariae from naiads in northeast Thailand.

One hundred and eleven naiads from six different dragonfly species were investigated for the presence of metacercariae. Sixty-nine animals (62.2%) were infected with intensities up to more than 150 cysts per animal. The metacercarial cysts were characterized by light and scanning electron microscopy. Two types of metacercariae could be differentiated by morphological features of cyst surface, cyst wall and size.

Current status of food-borne parasitic zoonoses in West Germany.

The present status of food-borne parasitic zoonoses in West Germany is characterized by a relatively high frequency of toxoplasmosis, sarcocystosis and Taenia saginata infections. From empirical data it can be estimated that 4% of the German population become infected per year by Toxoplasma gondii as well as by Sarcocystis species (S. hominis, S. suihominis). The number of T. saginata infected persons is reckoned at 900,000, which is equal to an average prevalence of 1.5%. Due to meat inspection and to modern methods of breeding and keeping pigs trichinellosis and Taenia solium infections have become rare diseases. According to eating habits there are only sporadic cases of fascioliasis and anisakiasis. Whether Diphyllobothrium latum and Opisthorchis felineus are still endemic, is unknown; it seems that the influx of refugees from areas of high endemicity never created new foci in West Germany.

Trichinellosis and trichinellosis control in Germany.

In nineteenth century Germany, trichinellosis was a relatively frequent disease. From 1861 to 1890 more than 12,500 cases, with an average mortality rate of 5%, were reported. As a consequence, trichinoscopy was made compulsory for the kingdom of Prussia in 1877, and a respective law was issued on June 3, 1900, for Germany as a whole. This measure led to a considerable decrease in human trichinellosis, reaching a minimum of only 49 cases for the period 1931-1940. The decrease in human cases was correlated to a constant decline of prevalence in pigs. However, after World War II, ten epidemics of human trichinellosis occurred with a total of about 2,000 cases. Sources of infection were illicitly slaughtered pigs, minced pork and sausages of partly unknown origin, and uninspected wild boars (Sus scrofa). Today, besides pigs, wild boars can be regarded as main sources of human infections. During the last two decades, two positive wild boars have been detected every year, thus demonstrating that a sylvatic cycle still exists. Measures to control trichinellosis in Germany have been limited to meat inspection. Before 1978 the only method allowed was trichinoscopy of compressed muscle samples. Then the pooled sample digestion technique and the magnetic stirrer method were introduced, which was later improved and automatized by use of the Foss Electric Trichomatic 35 and of the GMP 50 as a sampling device.