PubMed · 4207931
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C D Severson, N A Greazel, J S Thompson. 1974. Micro-capillary agglutination.. https://doi.org/10.1016/0022-1759(74)90078-7
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Diagnostic serology by use of elementary body agglutination is the most useful serologic method for diagnosis of chlamydiosis in birds, because it detects only IgM activity. A titer of 10 in budgerigars, cockatiels, and lovebirds and of > or = 20 in other types of birds is interpreted as being indicative of current infection. Latex agglutination, with detects IgM and IgG activity, may be useful in detecting large changes in titer. Direct complement fixation, detecting only IgG activity, is usable to detect past infection whenever elementary body agglutination and latex agglutination titers are < 10. Limitations of serologic results necessitating additional confirmatory testing are lack of titers in the acute phase of disease and diagnostic titers in clinically normal birds with low-grade chronic infections and in birds with prolonged maintenance of titers. Additional suggested examinations are chlamydial culture by use of choanal/oropharyngeal swab samples, WBC count, determination of hepatic-associated enzyme activity, chlamydial ELISA by use of the aforementioned swab samples, and additional serologic testing.
A comparison was made of the agglutination and lysis of three strains of Trypanosoma cruzi in gut extracts and hemolymph of Rhodnius prolixus and the results obtained were correlated with the success or failure of the parasite strain to infect the digestive tube or to survive in the hemocel after inoculation. Both T. cruzi strains Dm28c and Cl urine 35 days after feeding with parasites. Concomitantly, both of these strains were agglutinated but not lysed by the crop extracts. In contrast, T. cruzi Y strain parasites rapidly disappeared from the gut and showed no agglutination, but some lysis, in the crop extract. Following inoculation into the hemocel, only the Cl strain survived at high levels and was also the only strain agglutinated significantly in the hemolymph. Both Dm28c and Y strains rapidly disappeared from the hemocel with the former parasite being removed more slowly than the latter, probably due to clearance by the cellular defenses. The rapid clearance of the Y strain was correlated with the presence of a high titer lysin in the hemolymph. Subsequent experiments using FITC-labeled lectins and FACS to probe the carbohydrates on the parasite surfaces showed significant differences between the three strains. Thus, only Dm28c was stained strongly by Arachis hypogea (PNA) lectin, indicating the presence of galactose/N-acetylgalactosamine residues, and Dm28c and Y strains by Phytolacca lectin for N-acetyl glucosamine moieties. Finally, the fact that, in contrast to Dm28c and Y, the Cl strain strongly interacted with Triticum vulgaris (WGA) but not with Phytolacca lectin may be due to the presence of N-acetyl neuraminic acid residues on these organisms. These surface carbohydrate differences may be correlated both to the behavior and agglutination variations between the three strains recorded in this work.
A seroepidemiological survey of Toxoplasma gondii infection in sheep and goats was conducted in the Madrid region of Spain. Sera were collected from 60 herds, for which farming management information and other relevant data for their characterization were also obtained through a questionnaire. The seroprevalence was 11.8% (64 out of 541), using the modified (2-mercaptoethanol) direct agglutination technique with a 1:64 cut-off titre. The relationship between seropositivity and the variables in the questionnaire was assessed by multivariate analysis. Four variables were found to be significantly associated with seroprevalence. Two of them, the presence of cats and a previous history of abortion outbreaks in the farm, were factors known to be linked with toxoplasmosis, indicating the validity of the serological data. Seropositivity was also related to a lack of replacements in the preceding year. Proximity to other farms appeared to be a protective factor negatively associated with seropositivity, probably because it was an indicator of proximity to an urban area and the availability of local sanitary facilities.