Choice of sample size in parasitological experiments

One of the most awkward practical problems confronting a research worker setting up an experiment is to decide how big the experiment should be. The larger the number of subjects then the smaller is the degree of uncertainty in the conclusions; but large trials are costly and may have to be of long duration, so there is every incentive to keep trials as small as possible. Statistics is the science of coping; with uncertainty, and in this article Michael Healy explains the statistical basis that helps to decide how big a sample size should be - how to balance minimum error rates with optimal cost efficiency.     

Main parasitological problems of Italian fish farms

The speaker commented on the chief problems of parasitology found in Italian fresh water fish farms (troutfarming) and warm water pond farms (eel-, catfish-, cyprinids-, lagoo-fishfarmings). He discussed the most common fish losses connected in Italy with the diseases due to protozoans, worms, and crustaceans. The not yet solved and serious uncertainities which need priority in the research are, according to the speaker, the control of the amebiasis of hatchery rainbow trout, the incysted icthyophtiriasis of various fresh water fishes, the rainbow trout myxosomiasis (Whirling disease), and the argulosis of eel reared in brackish water lagoons. He concluded by emphasizing the need of a larger interest by Italian scientists on parasitic diseases of farmed fish. Without knowing and controlling them, it will be hard to program viable acquaculture industries.     

Prevalence of viral, bacterial and parasitological diseases in rats and mice used in research environments in Australasia over a 5-y period

Viral, bacterial and parasitological infections in rats and mice used in biomedical research continue to occur despite improved housing and biosurveillance. The presence of disease in laboratory animals can lead to spurious results for research undertaken in universities, research institutes and the pharmaceutical industry. Here the authors report the results of serological, microbiological, parasitological and molecular tests done on mice and rats from Australasia submitted to a rodent health monitoring laboratory (Cerberus Sciences) from 2004 to 2009. In tested mice, norovirus was the most prevalent virus and ectromelia virus was the least prevalent virus. In tested rats, pneumonia virus of mice was the most prevalent virus and adenoviruses 1 and 2 were the least prevalent viruses. In mice, Helicobacter hepaticus was the most prevalent bacterium, and in rats, Proteus spp. were the most prevalent bacteria. The most common positive helminthological finding in mice and rats was the presence of all pinworms (including Aspicularis spp. and Syphacia spp.). The most common positive protozoan findings in mice and rats were Chilomastix spp. and Trichomonads.     

Cryptosporidiosis in children and adults: parasitological and clinico-epidemiological features

By using the elective diagnosis methodology for Cryptosporidium (modified Ziehl-Neelsen and Heine stainings), 481 faeces samples from patients--children and adults--presenting acute or prolonged gastroenteritis and also from asymptomatic ones, but with professional, immunological or pharmacological risk for infection, were studied. Twelve Cryptosporidium positive cases were identified, meaning a general prevalence of 2.48% Cryptosporidium infection was detected in all investigated epidemiological groups: children, animal handlers, immunodeficient patients, immunocompetent adults with acute gastroenteritis. The risk factors hierarchy elicited the role of children collectivities attending, for acquiring the parasite in infantile cryptosporidiosis, while the opportunistic and zoonotic feature of the disease was especially present in adults' cryptosporidiosis. The assessment of cryptosporidiosis evolution, according to patients' immune status, has not allowed an obvious clinical discrepancy, since the immunocompetent subjects with professional risk had presented a prolonged oocysts excretion. The different clinico-epidemiological and parasitological features of Cryptosporidium infection are commented and the importance of applying Cryptosporidium methodology in current diagnosis practice is emphasized.     

The concept of the parasitological typing of lakes

The parasitological typology of lakes is proposed (with example of the Karelia-Kola limnological region). The characteristics of the main types of lakes with allowance of the parasitological data are given. The parasitological typology of lakes is based on studies of the parasite fauna diversity and differs from the trophical classification for lakes proposed by S. V. Gerd (1949).     

医学检验专业医学寄生虫学与检验课程教学改革初探

目的改革医学寄生虫学与检验理论与实践教学方法,提高教学质量。方法框架式讲授理论与实验内容后,引入案例,通过启发式教学方法引发学生兴趣;以问题为导向,进行探究式学习,以专业需求为目标,设专题实验室,以实践性和综合性实验为主导,改革课程知识安排顺序和考核评价方法。结果学生学习主动性提高,专业重点清晰。结论教学改革取得满意的效果。     

Lessepsian fish migration: genetic bottlenecks and parasitological evidence

As a rule, non‐indigenous species (NIS) populations derived from biological invasion events represent a subset of the genetic diversity of the source population. In biological invasions, host–parasite interactions play an important role, and parasitological data for NIS populations can provide useful information such as their area of origin, mechanism of invasion and prospects of success in the new habitat. When both genetic and parasitological data are available, and they suggest the same scenario, the history of an invasion can be inferred with no discrepancy, but when data cannot be reconciled an alternative model should be considered. In this study a comparison of genetic and parasitological data for the Lessepsian migrant the bluespotted cornetfish, Fistularia commersonii, in the Mediterranean Sea presents the opportunity to evaluate the compatibility of information of this nature, and to propose possible invasion scenarios consistent with evidence provided by both criteria.     

Serological and parasitological prevalence of Toxoplasma gondii in wild birds from Colorado

Ground-feeding birds are considered important in the epidemiology of Toxoplasma gondii because they serve as indicators of soil contamination by oocysts, and birds of prey are indicators of T. gondii prevalence in rodents and other small mammals. Cats excrete environmentally resistant oocysts after consuming tissues of T. gondii -infected birds. In the present study, sera and tissues from 382 wild birds from Colorado were tested for T. gondii infection. Antibodies to T. gondii were found in 38 birds with the use of the modified agglutination test (MAT, 1∶25 titer). Tissues (brains, hearts) of 84 birds were bioassayed in mice. Viable T. gondii was isolated from 1 of 1 barn owl (Tyto alba), 1 of 5 American kestrels (Falco sparverius), 1 of 7 ferruginous hawks (Buteo regalis), 1 of 4 rough-legged hawks (Buteo lagopus), 2 of 13 Swainson's hawks (Buteo swainsoni), and 1 of 25 red-tailed hawks (Buteo jamaicensis). This is the first time T. gondii has been isolated from the barn owl, ferruginous hawk, rough-legged hawk, and Swainson's hawk.