Granuloma disease in flocks of productive layers caused by Tetratrichomonas gallinarum

Abstract

In 2013, seven outbreaks of granuloma disease occurred in Dutch flocks of productive layers housed on different farms. These outbreaks were characterized by increased mortality and high incidence of granulomas, mainly in caeca (340/408 hens = 83%) and livers (69/408 hens = 17%). Mortality started to increase between 21 and 35 weeks of age and reached 3.7% to 11.0% exceeding the breeder's norm in periods ranging from 9 to 48 weeks. Some flocks also showed decreased egg production and/or loss of mean egg weight. All affected flocks were linked to one rearing farm, which therefore seemed to be the source of the disease. However, no signs of disease had been observed at this rearing farm. Sentinel hens placed in one of the affected flocks to determine whether the disease had an infectious nature developed granulomas identical to those seen in the outbreaks. Next, by fulfilling Koch's postulates it was shown that Tetratrichomonas gallinarum was the aetiological agent of the granuloma disease. The condition was reproduced in mature specified pathogen free White Leghorn hens (GD - Animal Health, Deventer, the Netherlands) by inoculation via both an artificial and a natural route with a well-defined axenic T. gallinarum isolate obtained from one of the affected flocks. Other causes of granuloma disease were excluded.

Coligranulomatosis (Hjärre and Wramby’s disease) reconsidered

“…The disease outbreaks described in Table 1 closely resembled severe granuloma disease recently described in the Netherlands, which was caused by T. gallinarum (Landman et al, 2016). In our opinion the former outbreaks were possibly wrongly diagnosed and may have been caused by T. gallinarum.…”

“…The authors of the papers summarized in Table 1 did not report the presence of protozoal-like cells in their HE-stained tissue sections. However, this does not rule out T. gallinarum as the causative agent, as this parasite was not seen in named sections of granulomas in chickens (Landman et al, 2016).…”

“…The authors mentioned in the foregoing text of this section did not report the presence of protozoal-like cells other than coccidia. As already stated in the previous paragraph, this certainly does not mean that T. gallinarum can be ruled out as the aetiological agent (Landman et al, 2016).…”

“…The condition was reproduced in mature SPF White Leghorn hens by inoculation via both an artificial and a natural route with a well-defined axenic T. gallinarum isolate obtained from one of the affected flocks. Other causes of granuloma disease were excluded (Landman et al, 2016).…”

Do we really need to reconsider coligranulomatosis (Hjärre and Wramby’s disease) in poultry?

“…The authors conclude that the aetiology of coligranulomatosis in some published cases in chickens, turkeys and quails should be reconsidered due to the lack of successful reproduction, which does not satisfy the requirements of Koch's postulates. The clinical appearance was characterized by severe morbidity and mortality, and its similarity to that in a series of cases of layers, which showed granulomas in different organs, published by Landman et al (2016), supports reconsideration. In the same study the authors attributed seven outbreaks of the disease in layer flocks to infection with Tetratrichomonas gallinarum.…”