White blood cell count in birds: evaluation of a commercially available method.

BACKGROUND: To conduct a hematological analysis of avian blood samples, standard automated cell counting is unreliable because all avian blood cells are nucleated. Therefore, quantitative white blood cell counting in birds is still performed manually, whereby the Natt-Herrick method is widely used in veterinary laboratories. The aim of this study was to evaluate a new commercially available single test system for avian white blood cell counting, the Natt-Herricks-Tic®, which would allow easy in-house analysis by clinicians or technicians. A total of 40 avian ethylenediaminetetraacetic acid (EDTA) blood samples from 24 different species were included in the study. To assess method agreement, each blood sample was analyzed for total white blood cell count with the test method and the Natt-Herrick reference method. To determine the imprecision of the reference method and the Natt-Herricks-Tic® method, the noncorrected white blood cell count was determined ten consecutive times from one avian EDTA blood sample for each method. RESULTS: The Natt-Herricks-Tic® method performed well concerning staining quality and countability of the granulocytes by the hemocytometer. In the agreement study, the Natt-Herricks-Tic® method showed a small proportional systematic error with a small positive mean bias of 282 white blood cells/µL but had wide 95% limits of agreement (- 4683 cells/µL to 5227 cells/µL), indicating random error. The precision study resulted in a coefficient of variation of 16% for the Natt-Herricks-Tic® method (the mean ± standard deviation: 9.7 ×  103/µL ± 1.5 × 103/µL) and 23% (the mean ± standard deviation: 7.9 × 103/µL ± 1.8 × 103/µL) for the reference method. CONCLUSIONS: The Natt-Herricks-Tic® method showed acceptable precision for a manual method and demonstrated good agreement with the reference method. It can be recommended as a reliable and suitable method for determining white blood cell counts in avian EDTA blood if nonstatistical quality control measures are used in the daily routine. The application of individual reference intervals for the interpretation of white blood cell counts in birds may improve the diagnostic performance of this important analyte in a clinical setting.

TRANSMISSION OF PTERYGODERMATITES NYCTICEBI IN A COLONY OF GOELDI'S MONKEYS ( CALLIMICO GOELDII) AND EVALUATION OF TREATMENT AND CONTROL.

Over a 2-yr period, four Goeldi's monkeys ( Callimico goeldii) died in a private zoo due to infections with the spirurid nematode Pterygodermatites nycticebi. Therapeutic measures with different anthelmintics were not successful. Due to the severe consequences caused by these infections, different actions were initiated, including sanitation measures and controlling of potential intermediate hosts (coprophagous arthropods). To identify possible intermediate hosts, arthropod species detected in the enclosure-parasite-free German cockroaches ( Blattella germanica), European earwigs ( Forficula auricularia), and rough woodlice ( Porcellio scaber)-were experimentally fed with feces of monkeys with patent P. nycticebi infections, resulting in established infections with third-stage larvae (L3) in roaches and earwigs. Furthermore, spiruroid L3 were detectable in 43% of the roaches and 30% of earwigs caught at the zoo. Polymerase chain reaction and sequence analysis of eggs, larval, and adult stages resulted in identical results, confirming the establishment of the parasite's life cycle in the zoo. This is the first documentation of the vector capacity of the European earwigs for P. nycticebi. As a measure of sanitation, a large part of the enclosure was emptied and cleaned. The Goeldi's monkeys were quarantined and treated with levamisole (7.5 mg/kg sc twice in intervals of 2 wk). Repeated coprologic examinations by zinc chloride flotation were undertaken. After the levamisole therapy, eggs were not found in the feces for 3 mo. However, shortly after resettling the monkeys into the sanitized enclosure, reshedding of small amounts of spirurid eggs was observed, whereupon deworming with levamisole was prescribed several times per year. The sanitation measures and the elimination of the intermediate hosts in a natural enclosure are presented as an example of the long-term controlling of the parasites.

In vivo viability of Echinococcus multilocularis eggs in a rodent model after different thermo-treatments.

Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a serious and emerging zoonotic disease in many parts of the northern hemisphere. Humans but also primates and other accidental hosts can acquire the infection by the ingestion of eggs excreted by the carnivore definitive hosts, e.g. after hand contact with egg-contaminated environments or by consumption of contaminated food or beverages. The goal of this study was to develop a sensitive in vivo method to determine the viability of E. multilocularis eggs and to establish suitable conditions (optimal temperature, exposure time and humidity) for their (prophylactic) inactivation. The sensitivity of a rodent model was evaluated and, conclusively, C57Bl/6 mice were most susceptible to subcutaneous inoculation of small numbers of sodium hypochlorite-resistant oncospheres, even more than to oral inoculation of mature eggs. In the second part of the study, various combinations of exposure temperature (between 45 °C and 80 °C), times (between 30 min and 180 min) and relative humidity (70% vs. suspended in water) were tested. After heat treatment in an incubator, the sodium hypochlorite resistance test was used to assess in vitro egg viability at the time of inoculation. Subsequently, the infectivity of the oncospheres was evaluated by subcutaneous inoculation in mice. Eggs exposed to increasing temperatures were more resistant to heat if suspended in water as compared to eggs exposed on a filter paper at 70% relative humidity. As survival of eggs in water droplets on the vegetables cannot be excluded, further experiments were performed with eggs suspended in water only. Eggs were infectious after heat exposure at 65 °C for up to 120 min, however, no echinococcosis developed after treatment of the eggs at 65 °C for 180 min or at 70, 75 and 80 °C for 7.5, 15 or 30 min.

Detection of taeniid (Taenia spp., Echinococcus spp.) eggs contaminating vegetables and fruits sold in European markets and the risk for metacestode infections in captive primates.

Due to frequent cases of alveolar echinococcosis (AE) in captive primates in Europe, 141 samples of food, which consisting of vegetables and fruits, were investigated for contamination with egg-DNA of taeniids. Each sample consisted of at least 40 heads of lettuce as well as various vegetables and fruits. The samples were purchased at different times of the year: either from September to November (autumn), originating from greenhouses or fields in the Basel region in the North of Switzerland, or in April and May (spring) when fruit and vegetables are sourced from throughout Europe from various wholesalers. Each sample was washed, and the washing water sieved through mesh apertures of 50 µm and 21 µm, respectively. The debris, including taeniid eggs, collected on the 21 µm sieve were investigated by a multiplex PCR-analysis followed by direct sequencing. In 17 (18%) of the 95 samples collected in autumn, taeniid-DNA was detected (Taenia hydatigena in four, Taenia ovis in three, Taenia polyacantha in two and Hydatigera (Taenia) taeniaeformis in five cases). Similarly, in 13 (28%) of the 46 samples collected during spring taeniid-DNA was detected (Echinococcus granulosus s.l. in two, Taenia crassiceps in one, T. hydatigena in two, Taenia multiceps/Taenia serialis in two, Taenia saginata in one and H. taeniaeformis in five cases). Although DNA of Echinococcus multilocularis was not found specifically in this study, the detection of other fox taeniids reveals that vegetables and fruit fed to the primates at the Zoo Basel at different times of the year and from different origin are contaminated with carnivore's faeces and therefore act as a potential source of AE infections.