BANAT’S UNIVERSITY OF AGRICULTURAL SCIENCES AND
VETERINARY MEDICINE - TIMISOARA
VETERINARY MEDICINE FACULTY
MATEI (FODOR) IONICA MIHAELA
INFECTIOUS CAUSES OF MORBIDITY IN
BROILERS IN THE WESTERN PART OF ROMANIA
DOCTORAL THESIS
SCIENTIFIC SUPERVISOR,
PROF. DR. HERMAN VIOREL
TIMIŞOARA 2009
ABSTRACT
This work was conceived as an extended study, in time and space, on the determination of infectious
causes of morbidity in broilers, in the Western part of Romania.
Data obtained by us represent both the results marked over a period of 8 years of investigation, in 18
poultry farms in the territory, who have requested our support in the diagnosis of disease, and the results of
laboratory tests carried out formally in the county laboratories.
The thesis contains 263 pages and it is structured in two parts. The first part (Chap. 1-12)
summarizes the main bibliographic database of scientific literature on the most common diseases, which
occur in broilers, and it is „The knowledge's level."
The second part is divided into 13 chapters, and in Chap. 1-12, it refers to the research on the
infectious causes that have produced morbidity in broilers in the Western part of Romania, over the period
2001-2009. Chapters 1-12 of Part 2 include materials and methods, the obtained results with their discussion
and partial conclusions, and in Chapter 13 of Part 2 are summarized the general conclusions that were
detached from the investigations.
The work is illustrated with a number of 80 figures, 29 tables and it is based on 402 bibliographic
titles.
The first part of the work is a summary of the currently available data related to the history,
geographical distribution, importance, etiology, epidemiological characteristics, pathogenesis, clinical signs,
anatomopathological findings and diagnosis in avian reovirus infections, Marek's disease, avian infectious
bursitis, avian infectious bronchitis, Newcastle disease, avian colibacillosis, avian mycoplasmosis,
staphylococcosis, pseudomonosis, Salmonella infections, aspergillosis and eimeriosis in broilers.
In Chapter 1 are presented the reovirus infections in birds, which are frequently associated with
increased mortality, viral arthritis/tenosynovitis and an overall decrease in performance, including the
unrealized gains in weight, poor feed conversion, unequal growth rates, confiscated of slaughterhouse and a
poor recovery on the market of the affected birds.
Chapter 2 handles the Marek's disease, which was only sporadically reported in some countries, until
1950, and later the disease evolved on all continents, due to the increase international exchange of poultry
materials. This disease produces economic losses due to immunosuppression and massive confiscated in
broilers following the development of tumors in some viscera and on the skin.
Chapter 3 presents the avian infectious bursitis, a known disease studied for over 50 years, which
continues to be a problem for the poultry industry. This disease is more present and more important as
advanced poultry plays a greater role in the economy of a country.
In Chapter 4 are presented data on avian infectious bronchitis, a disease that spreads quickly, as
reported and described in all continents. This disease is a constant threat to poultry, because of frequent
occurrence of new antigenic types, the losses by mortality of young chickens depending on the strain
virulence, immunity level and the chickens’ age at the time of the infection.
Chapter 5 presents Newcastle disease, which is a serious threat to poultry, because it can be
transmitted easy over long distances and because of the fast diffussibility and losses that may occur. The
disease has a great economic importance because it causes economic losses of poultry farming, due to high
morbidity and mortality (90%) and losses due to the restrictive measures imposed by the control plane.
Chapter 6 handles avian colibacillosis, commonly found in broilers, as colibacilli are omnipresent in
poultry farms and may also contaminate all areas of housing, feed, bedding and water. Colisepticemia is a
conditioned disease, in addition of the colibacilli, in its etiology being incriminated a number of favoring
infectious or non-infectious factors (overpopulation, ventilation deficiencies, humidity and generally the
inadequate microclimate).
In Chapter 7 is presented avian mycoplasmosis, which has spread worldwide, as a consequence of
the imports of poultry materials from the U.S.A. and Canada. In countries with intensive poultry,
mycoplasmosis produces significant economic losses through the reduced production of meat and eggs,
depreciation of carcasses, reduced fertility and decrease in the percentage of hatching, the high cost of
treatment and the prevention and control costs.
Chapter 8 approaches avian staphylococcosis, a disease which has been reported worldwide, in the
youth and adults, causing losses by mortality, depreciation of carcasses, therapy and control costs. The
disease was described more frequently in the broilers raised in batteries. About 50% strains of S. aureus
produce enterotoxins, which may subsequently cause food poisoning.
Chapter 9 presents avian pseudomonosis. This disease affects birds in all stages of development and
is favored by poor hygiene, poor nutrition, prolonged treatments with antibiotics against Pseudomonas
aeruginosa which is resistant, by the maintaining or antisepsis of hatching eggs in unsuitable conditions.
Pseudomonas aeruginosa participates as secondary germ infection or associated with other bacterial or viral
infections.
In Chapter 10 are given the infections with bacteria of the genus Salmonella grouped in two
categories. The first category includes infections with Salmonella gallinarum and Salmonella pullorum,
which mainly affects chickens and turkeys, causing the diseases called by the scientific literature of our
country avian tiphosis and, respectively, pulorosis. In some parts of the world, this type of infection was and
still is the cause of considerable economic losses, being a subject of extensive eradication programs. The
second type of infection is caused by mobile Salmonella serotypes, particularly the species of Salmonella
enterica, assigned as paratiphosis. The presence of infections due to these Salmonella species in commercial
flocks and the contamination of poultry products that enter in the human food chain represent a permanent
threat to public health. In recent years, Salmonella infections in poultry have been transformed from a
predominantly economic problem in a public health one, being in the attention of national and international
speciality fora.
In Chapter 11 is described avian aspergillosis, a disease usually postmortem diagnosed, in necropsy
examination of chickens, most on the basis of nodules from the lungs or air sacs. The source of infection is
usually represented by the bedding contaminated with mycetes. If the infection occurs around the age of
slaughter, the lesions due to aspergilli can lead to deteriorating carcass.
Chapter 12 presents eimeriosis (coccidiosis) in chickens, these ones being some of the most
damaging and common diseases of chickens, despite advances in chemotherapy, nutrition and genetics. The
disease is often diagnosed in the chickens brought to diagnostic laboratories, but most cases are diagnosed in
the farm. Expenses on preventive medication exceed 90 million dollars in the U.S.A. and more than 300
million dollars worldwide. Immunity is not as important for broilers, which are exploited for 6-8 weeks,
compared to young turkey or breeding birds, which are maintained for longer.
The second part, entitled "Own research" is written in 13 Chapters. Chap. 1-12 presents our
investigations in order to diagnose morbid entities that have evolved during the 8 years, in 18 broilers farms
from the counties in the Western part of Romania, while in Chap. 13 the general conclusions are
summarized.
We presented the results of epidemiological investigations, pursuant to the presence of anatomoclinical or epidemiological factors that led to suspicion of the infection with a pathogen.
Chapters 1-12 of Part 2 include: introduction and scope, materials and methods, results and
discussion and partial conclusions.
In the present research there were conducted the following tests: epidemiological (epidemiological
investigation, calculating of cumulative mortality, highlighting the source of infection and favoring factors),
clinical (general symptoms), anatomopathological (macroscopical and microscopical), bacteriological
(isolation of etiologic agent, phenotypic characterization of etiologic agent), serological (ELISA
immunoassay test, reactions of IHA and RSARL), polymerase chain reaction (genotypic characterization of E.
coli strains and strains of Marek’s disease virus, BIA virus), virusological (isolation of Newcastle disease
virus).
Epidemiological, clinical, anatomopathological investigations and laboratory examinations
performed to elucidate the infectious causes of morbidity in broilers from the West part of Romania led to
detachment of the following final conclusions:
Reovirosis was studied in two flocks of broilers reared on the ground, as following: a flock of 12
600 heads, where the disease has evolved both as arthritis tenosynovitis and as malabsorption syndrome and
the second flock of 16 000 heads, which was diagnosed only with the malabsorption syndrome.
No matter the evolution form, the diagnosis of reovirosis was confirmed by ELISA using the kit
FlockChek® Avian Reovirus Antibody Test Kit, provided by Affinitech Ltd. In the first flock of broilers, where
the reovirosis has evolved in both forms, there were clearly positive titres in 29 sera, respectively 60.42%, of
the 48 sera collected at the age of 23 days, and 35 positive sera, respectively 77.77% of the 45 sera collected
at the age of 37 days. In the second flock of broilers, with malabsorption syndrome, it has showed that all
serum samples collected at the age of 21 and respectively 42 days were positive.
ELISA showed peak titres of 1022 O.D. at the first blood collection and of 1453 O.D. at the second
blood collection, in the first flock of broilers, and the maximum titres of 3988 O.D. at the first blood
collection and of 7507 O.D. at the second blood collection, in the second flock of broilers. The fact that the
titres obtained in dynamic evolved upward excludes the hypothesis that these titres could be represented by
residual yolk antibodies, while it clearly indicates that in most cases the infection occurred after eggs
hatching, before the first sampling of serum, respectively before the age of three weeks, and that the
transmission was horizontal. Primary source of infection remained unresolved but, given the epidemiological
investigation result, there is the probability that this was represented by the shelters, equipment or vehicles
previously contaminated and not by the hatching station.
In the studied flocks, the clinical signs and the anatomopathological findings corresponded to
malabsorption and arthritis-tenosynovitis syndromes due to avian reovirus, with rare exceptions in the
absence of symptoms or lesions that would indicate any other disease to justify the mortality,
In this study, the extension of reovirosis by contagion was demonstrated by serological test results,
by increasing the number of positive sera from one test to another, and the titres increased from one blood
collection to another.
At the end of the growth period, the mortality did not differ significantly between the two flocks
depending on the evolution form of reovirosis. Thus, the first flock, distributed in two halls, the mortality
was 23.69% and 25.17% respectively, while in the second flock, it was 21.61%.
At the end of the observation period, the episodes of avian reovirosis ended with a mortality around
25% and a lower feed conversion, so the average weight of chickens was lower than the standard weight of
the respective hybrid, which led to extend the period of exploitation of chickens with two weeks.
Marek's disease (MD) was reported in two flocks of birds: a flock of broiler chickens and a flock of
laying hens, with significant losses in both cases. The relatively serious evolution of Marek’s disease was
possible because none of the two flocks have been vaccinated against that disease.
In both outbreaks, Marek’s disease diagnosis was based on clinical examination,
anatomopathological findings and histological examination and, in case of laying hens the diagnosis was
confirmed by PCR technique.
The clinical signs were different in the two categories of birds which presented Marek's disease. In
this regard, in the flock of broilers, prevailed: depression, loss of appetite, reduced feed consumption and
weight gain, while in the laying hens, from the seventeenth week of life, have prevailed: impossibility to
move at a rate of 30%, fallen wings in 18% and cachexia in 8% of the flock.
Both in broilers and laying hens, the morphopathological findings were characteristic of acute
visceral Marek’s disease form, and in the histopathological examination, there was found an increased cell
polymorphism: lymphocytes, lymphoblasts, plasmablasts, fibroblasts, along with red cells and circumscribed
or diffuse tumor infiltration, which sometimes does not allow the microscopic identification of organ of
origin.
In the flock of laying hens, the PCR technique revealed the viral genome of Marek’s disease virus,
which undoubtedly confirms the suspected epidemiological, clinical and anatomopathological diagnosis.
The mortality had close values in the two outbreaks. Thus, in both halls of broilers from farm S, in
which the Marek's disease has been diagnosed since the fourth week of life, mortality had values of 12.06%
and 11.8% respectively, and for the laying hens, also distributed in two halls, within the first 15 weeks of
life, the mortality was not too high, but the values were of 12.13% over the next 16 weeks, of which 11%
were due to Marek’s disease.
During the observation in four farms from Timiş and Hunedoara counties, the avian infectious
bursitis (AIB) evolved in broilers and chickens for breeding at different ages, but not earlier than 21 days in
any one of the farm. The evolution of AIB outbreaks was between 5 and 8 days, being correlated with
productive categories of chickens from those farms.
In AIB the clinical signs were characterized by sudden onset, horripilation, congestion of birds in
groups, white diarrhea, pericloacal itching, nervous signs, all of that being mentioned in the scientific
literature too.
For AIB, the mortality rate was different between the two categories of birds, being 15.44% in
broilers and 39.5% in chickens for breeding, which is more than usual losses in both categories of youth
poultry, if it had not evolved the AIB.
High mortality recorded in the AIB evolution suggested virulent strains and it was correlated with
the severity of morphopathological injuries having special significance for diagnosis of the disease,
especially the lesions located in bursa of Fabricius, which was affected in 100% of cases. Thus, initially the
creases of bursa were bold and covered by mucus and fibrin, and in some corpses we found congestion, and
in others the bursa was haemorrhagic. In addition, in all four farms were found congestion and generalized
haemorrhagic lesions present in pectoral and limb muscles.
Also in case of outbreaks of AIB described in the present work, and in other cases cited in the
scientific literature, avian infectious bursitis proved to be one of the most damaging diseases of broilers and
chickens for breeding, in the absence of vaccination, affecting almost systematic series after series, with
known effects: increased mortality, reduction in weight gain, reduction of the slaughter efficiency and
inhibition of post-vaccine and post-infectious immunogenesis ability, all of that being noticed by us in all
four studied flocks.
Avian infectious bronchitis (IB) was suspected based on epidemiological data and especially on
clinical and morphopathological ones, in a flock of broilers reared intensively, but it was invalidated due to
the negative results obtained by ELISA test, performed on 30 samples collected spread over 3 rounds.
The presence of 3 reactions (10%), respectively 1 suspect and 2 low-positive, who argued for a
possible evolution of avian infectious bronchitis, could be attributed to some low pathogenic strains of avian
infectious bronchitis virus that is believed to exist in the flocks of birds in our country, but in the episode
described by us was not the case as positive titres have not increased in number and level in the 2 and 3
blood collection, and they disappeared entirely. Therefore we attribute the presence of the 3 serological
reactions to the yolk transmission of antibodies post-vaccine of the flock queen.
Etiological diagnosis of the entity that simulated anatomoclinical and epidemiological the IB is still
unclear.
Due to the invalidation of avian infectious bronchitis by serological examination and invalidation of
other bacterial or viral infections by bacteriological and virusological exams, that episode was blamed on
technical and microclimate deficiencies.
In a specialized farm with a flock of 89 768 broilers (2 blocks), initially as a suspicion on clinical
and morphopathological signs, the diagnosis of Newcastle disease (ND) was then confirmed by
virusological and serological exams. This was the only outbreak of ND reported in the field and known to us,
as well as to laboratories from the counties in the Western part of Romania, in the last 8 years. It means that
the disease, rightly considered the most dangerous disease of birds, became a relative rare disease, well
controlled by veterinary-sanitary measures. When it appears is truly devastating, as we can see in the
outbreak studied by us and presented in this paper.
While there were instituted drastic measures of disinfection and restriction on movement between
the affected block and the block with smaller chickens, however the disease passed of one block to another
within a week. Since the infectious pressure was high, it was decided to re-vaccinate the chickens against ND
preventive ahead of schedule, but without be able to prevent the spread of the disease to the entire
population.
Broilers showed clinical signs characteristic of Newcastle disease: rapid breathing, diarrhea,
weakness, nervous signs, followed by prostration and death, and anatomopathological examination revealed
lesions of haemorrhagic proventriculitis (56%), haemorrhagic tonsillitis (28%), polyserositis (52%), catarrhal
enteritis (36%), sero-mucous sinusitis (26%), catarrhal laryngo-tracheitis (26%) and edema of bursa of
Fabricius (26%), which shows that it was a velogen strain with a mixed visceral tropism, pronounced both on
the digestive and respiratory tract.
In the studied outbreak of ND, laboratory investigations have shown that it was indeed a velogen
strain with high pathogenicity index (>1.75) that was contracted, as it was suspected, from the household
sector of nearby villages, but without this presumption to be demonstrated because ND had not been
previously reported in any household.
When the ND occurred, serological examination showed that the chickens were non-immune,
despite the fact that they had been vaccinated twice, but clearly ineffective. The first vaccination was in the
incubator and the second one in the term, but in drinking water, the latter being non-compliant with the rules
in our country for chickens raised on the ground in the industrial system.
Because the titres of sera tested by IHA remained at very low non-protective levels, even after the
second vaccination, we don’t have a definite explanation, but since the second vaccination was done in the
drinking water we suppose that there was a factor that completely inhibited immunogenesis, as could be, for
example, the chlorination of water used for diluting the vaccine (operator personnel not having knowledge of
the fact if the water was or not chlorinated from the station in that period); another possibility - or even
probability - would be that the vaccine against avian infectious bursitis, which was incorrectly given the day
before, to have induced inability of immunization of chickens against Newcastle disease.
The fact is that these chickens vaccinated twice against ND – if the vaccination from one day to
another was real - have proved to be highly susceptible to Newcastle disease virus and become sick in mass.
Disease evolution was particularly severe, claiming the loss of the entire flock of which 70 947 (79%)
chickens died following the disease, and the remaining 18 821 were killed, in accordance with legal
purviews to short the established quarantine period, because we know that any other measures would not
have led to their protection and to prevent the risk of virus dissemination beyond the farm.
Avian colibacillosis has been reported and studied in 18 farms specialized in raising broilers, and in
many households, where is practiced traditional growth of poultry, from the West part of Romania. In all
flocks where it was diagnosed avian colibacillosis, there were shortcomings of microclimate, the loss
through mortality varying by them.
There was isolated a total of 121 bacterial strains identified as E. coli, both from the bone marrow
and the internal organs. All the studied APEC strains fermented lactose on the two culture media (SS and
Levine), that biochemical character being considered constant in APEC strains. All lactoso-positive isolates
were further tested by the minimum set TSI, MIU, Congo red, only in few cases being necessary to use API
20E kit for confirmation.
The haemolytic activity of APEC strains was present only in 5 (4.13%) of the 121 isolated strains.
The synthesis of hemolysins is not a feature of APEC strains, as recorded both in scientific literature and own
research results.
The worldwide movement of poultry material is contributing to the dissemination of APEC strains
and thus to the dissemination of multiple resistance to antibiotics, which requires monitoring from this point
of view of the APEC strains isolated from intensively farmed poultry in reference laboratories, this aspect
being already put in practice in many countries. Following the 121 antibiograms of the E. coli strains isolated
during the last years, it was showed a strong phenomenon of increasing resistance to most antibiotics and
restriction of sensitivity, present in particular to newer antibiotics. Thus, the best results were obtained to
florfenicol (sensitivity over 90%).
Other 36 tested strains of E. coli were found to be sensitive for more than 50% to the following
antibiotics: flumequine (61.11%), enrofloxacin (58.3%) and norfloxacin (52.77%).
As regards the antibiotic resistance, the 121 tested strains were found to be resistant for more than
50% to the following antibiotics: doxyciline (92.57%), tetracycline (85.13%), neomycin (77. 69%),
ciprofloxacin and erythromycin (60.34%), spectinomycin (57.85%) and enrofloxacin (57.04%).
In the 36 tested strains of E. coli in the second series, the antibiotic resistance is almost similar, only
varying the proportions: neomycin (61.11%), amoxicillin (91.11%), lincomycin (88.88%) and tetracycline
(55.55%).
In the study of APEC strains, the PCR technique used in this research proved successful in
highlighting the genes ompA, iss and fimH, by using three multiplex type amplification reactions. The
obtained results showed that the 3 genes that encode pathogenicity factors are usually associated two or three
of them in the same strains.
The presence of the three genes of pathogenic factors is correlated with the ability to bind Congo
red, considered a phenotypic character of APEC strains discrimination, since in the present survey the 93
strains classified as belonging to APEC group that were positive by PCR were positive by the Congo red test
too.
The screening carried by multiplex PCR has established a correlation between high frequency of
APEC strains isolated from flocks with high mortality compared with other strains of E. coli isolated from
flocks with low mortality. So the multiplex PCR technique enables the early identification of APEC strains
and it can be a useful implement to warn the risk of serious episodes outbreaks of avian colibacillosis.
Avian mycoplasmosis was studied in three flocks of broilers reared on the ground in the industrial
system and in one flock of heavy breed chickens (parents of broilers) as the form of avian infectious
synovitis and as the respiratory form. It was not diagnosed any outbreak or case in chickens reared in the
traditional system, from where it can be deduced that, where the control of microclimate hygienic parameters
fails, the increase in intensive-industry system was the decisive factor favoring the emergence and evolution
of mycoplasmosis, during the 8 years of observation.
Avian infectious synovitis form was reported as dominant in one outbreak of mycoplasmosis in
broilers and in the one of broiler parents. In the outbreak of broilers, the disease was confirmed by ELISA
using the kit Mycoplasma Synoviae Antibody Test. Thus, at the age of 23 days, there were positive 22.9% of
the examined sera and, at the age of 37 days, there have been positive 26.66% of sera. In the flock of broiler
parents aged 11 weeks, all examined serum samples were found positive by RARL. The mortality in broilers
amounted to about 25% by the age of slaughter (42 days) and for parents of broiler, although morbidity was
almost 100%, mortality did not exceed 9%.
Infectious avian mycoplasmosis caused by M. gallisepticum was studied in two outbreaks of broilers
reared on the ground. In both flocks, serological tests showed no positive reaction in the first phase of
chickens’ life and the emergence of positive reactions after 3-4 weeks, as increasing amount, which shows
that the infection has not occurred vertically, but in the farm, either by contagion with germs from the earlier
series following an ineffective decontamination, or with germs from a hens flock, coexisting on the farm.
The noticed mortality in these outbreaks was about 17% in a flock and about 10% in the other one.
Avian staphylococcosis has been reported and studied only in one outbreak occurred in a poultry
complex of 12 000 broilers reared on the ground. The disease evolved between the days 24-27 of chickens’
life with symptoms and anatomopathological lesions characteristic to staphylococcosis.
From the staphylococcosis outbreak were isolated 14 strains of cocoid bacteria of which 11 were
biochemically identified as S. aureus by using API Staph and "Staphytect Plus" kits. The isolated strains of
S. aureus were sensitive to amoxiclav, enrofloxacin, flumequine, florfenicol, furazolidone and they were
resistant to erythromycin, spectinomycin, colistin sulfate, bacitracin, oxacylin, showing quite large
differences from the results of other authors and reflecting the lability of species S. aureus in terms of
sensitivity to antibiotics.
During the 4 days of disease evolution, overall mortality of broilers from the flock with
staphylococcosis was only of 0.8%, making that the described outbreak of avian staphylococcosis didn’t
behave like a devastating infectious disease.
Avian pseudomonosis occurred in a flock of several thousand of 1 day old chickens, following the
infection with Ps. aeruginosa, which was accidentally inoculated with anti-Marek vaccine. From all
observations, both on the purchased chickens from distributor farm and on those from the experimental lots
established in order to confirm the diagnosis of pseudomonosis, the lack of contagion was noted, confirming
that were sick only those chickens inoculated i.m. in the first day of life.
In the outbreak of pseudomonosis emerged after the accidental inoculation of the etiologic agent,
there was a morbidity of 2-3%, of which 20% died within 2-3 days. From the ill chickens that have not died
in the first 2-3 days, still died 2-3% the next 5 days. The remaining chickens were healed gradually without
any apparent sequel.
Pseudomonosis also has been diagnosed and studied in broilers at the age of 30 days, in which case it
was not detected some favoring or predisposing factor, but it could not be excluded that there was a primary
factor that would be made possible the infection with Ps. aeruginosa.
In broilers aged 30 days, over a period of 5 days that followed the emergence of the first cases of
pseudomonosis, losses by mortality due mainly to the septicaemical pseudomonosis has ranged from 20.64%
to 35.67%. At the end of chickens’ exploitation, mortality ranged from 24.17% to 39.67%, which signifies
that, although the outbreak of pseudomonosis development was short, more than 80% of the total recorded
mortalities all growth round were due to pseudomonosis.
Diagnosis of avian pseudomonosis should lead, in all cases, to the detection and neutralization of
predisposing or favoring factor, which made possible the emergence of the disease, after which the
preventive drug therapy is unnecessary, as pseudomonosis will disappear without any specific medication.
Salmonella infections with non-mobile and mobile Salmonella spp. have been identified both in
specialized poultry farms and households in five counties in the Western part of Romania, but in relatively
small proportions.
Although in the past Salmonella infections in poultry have been a great problem of poultry farming,
in the Western part of Romania, their incidence decreased over time, especially after 1999.
In the county laboratories of the five counties, Salmonella strains were isolated and typified both
from farms of broilers and from households where developed pulorosis and paratiphosis. At these samples
are added the 40 strains of Salmonella isolated from broilers in the laboratory of Infectious Diseases
discipline of FMV Timişoara.
In total, in the county laboratories and in laboratory of Infectious Diseases discipline of FMV
Timişoara there was isolated and identified from broilers a total of 93 Salmonella strains, of which 88 came
from intensive farming system and 5 strains from households.
The largest number of Salmonella strains was isolated in 2004, respectively 34 strains, which
corresponded with the highest number of outbreaks of salmonellosis in broilers, noted in the Western part of
Romania. The next year it was no longer any outbreak and it was no longer isolate any strain of Salmonella
in broilers, probably due to the prevention and control measures taken.
In contrast to past situations when non-mobile Salmonella infections predominated, producing
specific diseases in poultry - tiphosis and pulorosis - during the studied period, there were several outbreaks
of infection and there were isolated more strains of mobile Salmonella than non-mobile ones.
The highest number of the mobile isolated strains belonged to S. enteritidis type (50.53 %), followed
by S. arizonae (13.97%).
S. gallinarum was isolated from 21 corpses of chickens, of which in fact 20 came from the same
flock of broilers reared in intensive system.
Cultural and biochemical behavior of the isolates did not show notable deviations, such as to raise
questions regarding the taxonomic classification.
Following the laboratory examination, there was isolated and identified a total number of 93 strains
of Salmonella, most mobile and assigned to serogroup D, S. enteritidis probably. A total of 17 mobile strains
were within the serological group B and were derived from poultry farms, with the exception of 3 strains,
which came from households. There were also isolated strains belonging to some serogroups that have rarely
or never previously reported in Romania in broilers (3 strains of S. kambole, 2 strains of S. kortrijk and 2
strains of S. colindale). Isolation of the strains belonging to these serogroups, considered new in Romania, is
the result of importation of poultry material in recent years, that contributed to the dissemination of strains
on large geographic areas.
In case of Salmonella strains isolated by us, the antibiograms showed high sensitivity to antibiotics
less used in the practice of poultry (ciprofloxacin, amoxiclav and gentamicine) and considerable resistance in
varying proportions to the antibiotics used most frequently in the practice. The tested strains were resistant in
proportion of 59.13% to florfenicol, relatively recently introduced antibiotic in poultry practice, with very
good results in case of colisepticaemia but, as is seen, not in the case of salmonellosis.
Aspergillosis was diagnosed and studied only in one flock of broilers, with losses by death and
confiscated from slaughterhouse. The percentage of mortality attributable exclusively to the development of
aspergillosis in broilers was 4.7%.
The microclimate factors - changes in temperature, humidity, rainy season – and the presence of
mouldy straw bedding have played a decisive role in the onset and development of aspergillosis. In all cases,
the diagnosis of aspergillosis in broilers should result to the detection and neutralization of predisposing or
favoring factors, their removal leding to disappearance of the disease by default.
Clinical signs did not result in suspicion of the disease, but at the autopsy of broilers with
aspergillosis, the predominant lesions were granulomas of various sizes on the serous membranes from the
toraco-abdominal cavity, on air sacs, in the lung, pericardial area and on the kidney.
Diagnosis of aspergillosis was confirmed by biological test, from which was obtained the
transmission of A. fumigatus in broilers, that had respiratory symptoms characteristic to aspergillosis and
lesions similar to those seen in the confiscated from slaughterhouse.
In the flocks from the Western part of Romania, coccidiosis has been reported and studied in broilers
both in the intensive system, and in one mini-farm with extensive system, being identified the following
species of Eimeria: Eimeria tenella, Eimeria acervulina, Eimeria maxima, Eimeria mitis and Eimeria
praecox.
The parasitism with Eimeria spp. broke up after the age of 21 days. In the intensive system, E.
tenella and E. acervulina affected the broilers aged 3-5 weeks, whereas E. maxima occurred at the age of 4-6
weeks. In the intensive system of broilers’ growth, prevalence ranged between 0 and 74%, dependent on
growth conditions and in the outbreak of eimeriosis from the extensive system the infestation prevalence
reached 100%.
If compliance technology of broilers’ growth, eimeriosis does not cause health problems in chicken
flocks, but that still occurs, the coccidiosis may cause minimal or very large problems, dependent on the
promptness and effectiveness of established medications.
Making a comprehensive assessment of mortality losses produced by the diseases encountered
during the observation period in the flocks under observation, we can enumerate these diseases, in decreasing
order of produced mortality, in the flocks taken in the study, as follows: Newcastle disease - 70%,
pseudomonosis - 31.9%, mycoplasmal synovitis - 25%, reovirosis - 23.7%, avian infectious bursitis 15.44%, respiratory mycoplasmosis - 13.5%, Marek's disease - 12%, aspergillosis - 4,7%, avian
staphylococcosis - 0.8%. To the causes of losses due to infectious diseases in flocks of broilers, should be
added the losses due to colibacillar and Salmonella infections.
Certainly, in other circumstances, the amount of losses could be another, but for now, these data
offer an approximate predominance of each disease in all economic losses. Obviously, to the mortality
indicator should be added other indicators too, as the reduction of weight gain, expenses for the control of
those diseases, etc.