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ORIGINAL PAPER

Susceptibility of different turkey lines to Histomonas

meleagridis after experimental infection

Lotfi AbdulRahman & Hafez Mohamed Hafez

Received: 8 December 2008 /Accepted: 2 February 2009 /Published online: 17 February 2009# Springer-Verlag 2009

Abstract In the present investigation, three turkey lines,

namely wild Canadian turkeys (WCT), British United

turkey (BUT-Big6) and KellyBronze turkeys (KBT) were

compared for their susceptibility to infection with Histo-

monas meleagridis. All birds were kept on wood shaving as

litter from day 1 on during the entire observation period.

On day 28, 1820 birds per turkey line were infected with

H. meleagridis intracloacally. All birds were observed for

4 weeks after infection. The mortality rate was 95% in

WCT, 78% in BUT-Big6 and 75% in KBT. In WCT, the

first deaths occurred at day 6 and ended at day 13 post-

infection, whilst for BUT-Big6 and KBT, birds died from

days 10 to day 20. In KBT group, the mortality started at

day 10 and lasted until day 17 after infection. At necropsy,

all birds that died showed lesions typical for histomoniasis

in the caeca and liver. The obtained results demonstrate that

all tested turkey lines are susceptible to infection; however,

the mortality rate for the wild Canadian turkey is

statistically significantly higher compared to the other

tested two lines.

Introduction

Blackhead or histomoniasis is a protozoan disease primarily

of turkeys. However, several other species like chickens,

quail and peafowl are also susceptible. In the past,

histomoniasis has been controlled very well with

Dimetridazole as a treatment and/or Nifursol, which was

used as a feed additive. In the European Union, the last

therapeutic drug against histomoniasis was banned in 1995

and the last prophylactic drug in 2003. Since then, several

outbreaks of histomoniasis in turkey flocks caused consid-

erable economic losses. Cases in chickens and game birds

have occurred less frequently (Hafez et al. 2005a).

In turkeys, the disease is characterised by listlessness,

anorexia, droopy wings and yellow-sulfur-coloured faeces.

Infections with blackhead in turkeys are often fatal, with

high morbidity in survivors. It is the most fatal parasitic

disease of turkeys capable of causing mortality up to 100%.

Histomonas as parasite depends on complicated interactions

with caecal worms, earthworms, intestinal microflora and

coccidia to spread from flock to flock and to develop full

pathogenicity (McDougald 2003). Currently, the control of

histomoniasis is based on good hygienic measures at farm

level, on using drugs that reduce the presence of caecal

worms and other herbal products with variable results.

The genetics of resistance to disease is an area of great

interest in several animal species and poultry. Selective

breeding for resistan ce to pathogens in animals has

demonstrated that resistance and susceptibility to pathogens

are controlled by both genetic and environmental factors.

Genetic resistance to disease is a widespread phenome-

non in all animal species due to the genetic control of the

immune system. Especially in poultry, it is often possible to

find individual differences in susceptibility to most diseases

(Bumstead et al. 1991). Most of the investigations on

genetic resistance to disease in poultry have been carried

out in chickens and to less extent in turkeys. They focused

primarily on viral and/or bacterial diseases. However, some

studies have been on the genetic mechanisms involved in

resistance to coccidial infections and to Ascaridia galli in

chickens (Pinard-Van der Laan et al. 1998; Permin and

Parasitol Res (2009) 105:113116

DOI 10.1007/s00436-009-1369-1

L. AbdulRahman : H. M. Hafez (*)

Institute of Poultry Diseases, Faculty of Veterinary Medicine,

Free University Berlin,

Knigsweg. 63,

14163 Berlin, Germany

e-mail: hafez@vetmed.fu-berlin.de

7/27/2019 AbdulRahman & Hafez Mohamed Hafez

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Ranvig 2001). In addition, Curtice (1907) showed that

chickens are less susceptible to Histomoniasis than turkeys,

but more important in disseminating Histomonas melea-

gridis and Heterakis gallinarum. Furthermore, Al-Khateeb

and Hansen (1974) showed between chicken breeds some

differences in the susceptibility to histomoniasis after

intracloacal experimental infection. Recently, Reynaud et

al. (2005) compared the susceptibility of an industrial

heavyweight turkey strain with a traditional lightweight

strain to H. meleagridis infection. The response to infection

of the heavyweight strain was in every way comparable to

that of the traditional lightweight strain, with exception in

the course of the infection. The 100% mortality was

attained 7 days later in the industrial heavyweight turkey

strain compared to traditional light turkey strain.

The present investigation was carried out to compare the

pathogenicity of H. meleagridis in three different turkey

lines.

Materials and methods

Three turkey lines, namely British United turkey (BUT-

Big6), KellyBronze turkeys (KBT) and wild Canadian

turkeys (WCT), were used. WCT were bred in captivity for

about 30 inbred generations and not intentionally selected.

Eighteen to 20 birds per turkey line were used. The birds

were kept from the first day on wood shave as litter. On

day 28, the birds were infected with H. meleagridis strain

Turkey/Germany/GB 551/04, which was isolated from

naturally infected meat turkey flock and confirmed using

real-time polymerase chain reaction (PCR; Hafez et al.

2005b). The strain was proven to be free from Tetratricho-

monas gallinarum and Blastocytis sp. using PCR as

described by Grabensteiner and Hess (2006). Each bird

received 1 ml modified Dwyers medium (Van der Heijden

et al. 2005) containing 300,000 histomonads intracloacally.

All birds were observed for 4 weeks after infection and

daily mortality was recorded. Postmortem was conducted

on all birds that died. After 4 weeks, the surviving birds

were euthanised and examined for pathological changes.

Lesions in caeca and liver were scored according to

McDougald and Hu (2001). From all turkeys which died

in the course of the study and survivals that were

euthanised at the end of the trial, samples were taken and

tested using real-time PCR.

Statistical methods

The KaplanMeier method was used to construct survival

curves, which were then compared by the log-rank test,

with correction for multiple comparisons. A value of P