Epidemiology of haemotropic Mycoplasma ovis in selected small ruminant flocks and host cell responses of mice to M. ovis infection
Haemotropic Mycoplasma ovis is an emerging zoonotic epierythrocytic parasitic bacterium that causes haemolytic anaemia, decreased production outcomes and mortality in sheep and goats. Isolated clinical cases of haemotropic mycoplasmosis have been documented in Malaysian small ruminants since the...
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| Yazar: | |
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| Materyal Türü: | Tez |
| Dil: | English |
| Baskı/Yayın Bilgisi: |
2021
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| Online Erişim: | http://ethesis.upm.edu.my/id/eprint/16212/1/FPV%202021%2014%20T.pdf |
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| Özet: | Haemotropic Mycoplasma ovis is an emerging zoonotic epierythrocytic parasitic
bacterium that causes haemolytic anaemia, decreased production outcomes and
mortality in sheep and goats. Isolated clinical cases of haemotropic mycoplasmosis
have been documented in Malaysian small ruminants since the early 1990s and recent
survey of selected flocks in Selangor also reported an association between M. ovis and
a severe nematode worm burden in goats. Although the assay of acute-phase proteins
and cytokines offers cheaper and sensitive alternatives as early markers of infection,
their role in haemoplasma diagnosis is unknown. This study was designed to
investigate the epidemiology of M. ovis in selected small ruminant flocks and
determine the clinical responses of cytokines, acute-phase proteins, and female
reproductive hormones in mice model. Samples and data were collected by crosssectional
survey of 5 flocks in Negeri Sembilan, Malaysia. Giemsa-stained blood
smears were examined to detect M. ovis and classify infection severity as mild (1-29%
infected red cells), moderate (30-59%) or severe (>60%) and microhaematocrit
centrifugation was used to determine PCV. Sodium chloride floatation was used for
detection of GIP followed by McMaster faecal egg count (FEC) to classify infection
severity as mild (50-799), moderate (800-1200) or severe (>1200). Laboratory mice
(n=24) were inoculated with mild (1-29%), moderate (30-59%) and severe (>60%)
doses of M. ovis and observed for weekly changes in PCV and parasitaemia. Serum
samples obtained after euthanasia were used for quantitative ELISA assay of
inflammatory and reproductive markers while organ samples were processed by
routine H&E staining. Examination of blood smears revealed an overall M. ovis
prevalence of 50.7% with a higher risk among breeds, pregnant and lactating animals.
Faecal analysis revealed 82.2% incidence of GIP, especially Strongyle/Coccidia
(50.9%) co-infection with different patterns of EPG and OPG in among small
ruminants. There was a higher incidence of mild GIP infections and M. ovis/Mixed
GIP (24.9%) was associated with a lower mean PCV. A higher mean parasitaemia was
observed in the co-infections of M. ovis/Mixed GIP (29.72±2.02) and a lower mean PCV coincided with severe M. ovis or nematode infection (25.23±0.741). Mean PCV
correlated negatively with EPG output (r = -0.214, p=0.002) and parasitaemia (p=
0.0009, r=-0.18). M. ovis cells appeared in the blood films within one-week and
reached a dose-dependent peak parasitaemia in the 4th-week pi with a significant and
dose-dependent drop in PCV at weeks 2 & 3 post infection (pi). The serum
concentration of haptoglobin (Hp) decreased significantly (p<0.05) by 48.7% in GPsevere
(3.92±0.95 μg/ml) compared to the GP-control (7.6±0.9μg/ml), while serum
amyloid A (SAA) increased significantly (p<0.05) by 89% in the severe infection
group (16.8±1.2μg/ml) compared to the GP-control (8.9±2.4μg/ml). Serum
progesterone increased significantly (p<0.05) by 166% in GP-severe (27.4±1.0ng/ml)
and 96% in GP-moderate (20.2±2.4ng/ml) while oestrogen levels decreased
significantly (p<0.05) by 52.9% in the GP-severe (10.38±2.3ng/ml) than the GPcontrol
(22.1±0.6ng/ml). The ovary in GP-severe showed mild leucocytic infiltration,
vacuolation and hypertrophy of lutein cells. In the spleen, there were extensive
haemorrhage, hypercellularity, infiltration of neutrophils and macrophages in the red
pulp. In the lymph node, there was congestion with diffused cellular hyperplasia while
the liver showed increased size and number of Kupffer cells, congestion of sinusoid,
diffused necrosis of hepatocytes and leucocytic infiltration. The kidneys showed a
severe proliferative lesion in the glomerulus, leucocytic infiltration and congestion of
the renal veins. Haemotropic M. ovis and gastrointestinal parasites were common in the
study area and the risk of M. ovis infection depends on the breed and physiological
status of small ruminants. Dysregulated secretions of female reproductive hormones,
changes in acute phase proteins, and the cellular changes in the ovary are novel aspects
of this study which shades light on the pathogenic mechanisms of haemoplasma
infection. |
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