Mycoplasma Chronic Respiratory Disease

Poultry industry is one of the fastest growing segments of the animal industry. The worldwide consumption of poultry is increasing. Today's bird has the potential to grow rapidly because of intensive genetic selection so they are more susceptible to stressors of the respiratory and circulatory systems.

The poultry industry faces the maximum economic losses by increase in mortality resulting from ascites, heart attack, heat stress and respiratory complications. Therefore, the respiratory system must function properly and can not be compromised if maximum performance is to be realised.

Managing respiratory disease is important to get the most out of the bird's genetic potential. Respiratory disease in poultry is the result of complex interaction of several stressor factors such as presence of viral and Mycoplasma challenge, bird handling and transport, weather changes or environmental fluctuations, diet changes, facility or management inadequacies and routine vaccination can all upset the normal physiology and homeostasis of birds. Of all the stressor factors, pathogen interactions play the most significant role in development of respiratory disease complex and the Mycoplasma infection are responsible for major losses.

Mycoplasma gallisepticum is the most economically significant Mycoplasma pathogen of domestic avian species, and has a world-wide distribution. All species of birds of all ages are susceptible to chronic Mycoplasma infection. Mycoplasmas are very highly evolved bacteria that, over time, have lost many of their non-essential genes. Because of fewer genes than any other known free-living organism, so they are totally dependent on their host for nutrition and survival. Mycoplasmas are relatively short-lived outside the host as they do not have a protective cell wall. They are assumed to be susceptible to the commonly used disinfectants therefore good hygiene is a first line defence on a commercial poultry unit (1).

A number of different agents are involved in the aetiology of this disease. These include M. synoviae or M. gallisepticum in chickens, M. meleagridis and M. iowae in turkeys. M. synoviae is usually less pathogenic.

When Mycoplasma infection interacts with common respiratory field viruses or vaccines, immunosuppressive agents and poor management practices, it leads to chronic respiratory disease (CRD). With secondary Escherichia coli infection further complicating the interaction, it becomes a complicated chronic respiratory disease (CCRD) and the resulting losses can be catastrophic (2, 3 & 4).

It is usually transmitted through eggs, feed, water, droplet infection, and by care takers (5). E. coli is a secondary invader of Mycoplasma-infected birds. Aerosol spread occurs. Severe ND, IBV or ILT reactions may occur after vaccination, especially if given by spray to chicks previously infected with Mycoplasma or E. coli.

Environmental stress factors such as increased or decreased temperature, high concentration of ammonia, dust in the air, and other factors associated with poor ventilation, may act as predisposing factors.

The disease is characterized by loss of appetite, dullness, depression, tendency to huddle together, coughing, tail bobbing when breathing, emaciation, respiratory rales, sneezing, open mouth breathing, conjunctivitis, periorbital swelling, poor growth, decreased feed consumption and increase in mortality (6 & 7).

 

Fig. 1 Poultry showing dullness and depression (8)

 

Fig. 2 Poultry showing conjunctivitis, periorbital swelling and eyelid edema (8)

 

Fig. 3 Cloudy appearance of the abdominal airsacs (11)

Fig. 4 Pericarditis and perihepatitis (11)

 

 

Fig. 5 Severe tracheitis. Both tracheas are congested and the upper sample has mucopurulent material in the lumen (12)

 

Fig. 6 Air sac showing coccobacilliform bodies surrounded by mononuclear cells (13)

 

 

Fig. 7 Air sac showing presence of fibrinous and serofibrinous exudates (13)

Fig. 8 Lung showing accumulation of serous exudates in tertiary bronchioles and atria. Increased cellularity of air capillaries (14)

Fig. 9 Giant cell granuloma in air capillaries (14)

 

Fig. 10 Accumulation of haemorrhagic exudates in tertiary bronchioles and atria (14)

Fig.11 Larynx showing lymphofollicular reaction in submucosa (14)

 

Fig. 12 Trachea showing hypertrophy, hydropic degeneration and tuboalveolar elongation of intraepithelial glands (14)

Biochemical studies (15)

Serological test (16 & 17)

Molecular techniques (18)

Fig. 13 & 14 Mycoplasmal colonies on Edward's PPLO agar (19)

 

Fig. 15 & 16 Mycoplasmal colonies with Diene's stain on Edward's PPLO agar (19)

Therapy of CCRD is complex, and there is really no sure shot treatment to completely eliminate Mycoplasma- infected birds, except elimination of the flock.

Fluoroquinolones (Enrofloxacin, Danofloxacin, Norfloxacin, Flumequin etc.) are on withdrawal phase world- wide, owing to their deleterious effects to public health through cross resistance to human strains of Campylobacter and other bacteria.

Various antibiotics like Tylosin, Tiamulin, Tilmicosin, Aivlosin, Tetracyclines (mainly Doxycycline, Chlortetracycline, Oxytetracycline), Spiramycin, Erythromycin, Gentamicin and Ketasamycin, Neomycin, Colistin, etc. are being used alone or in various combinations to cure and control the disease, with variable success, owing to mixed response to resistance development in the various microbes. Montajat has been monitoring and focussing on the resistance menace of the existing antibiotics, and has been substantially investing on the market research, clinical studies and R&D. It has been helping the local farms through onsite consultancy, and marketing numerous products to combat this menace. Some of the known brands are- Rythrocol, Florjat, Micojat, Spectolin, Montcol, Doxyjat, Rythrojat, Enrojat, Kimox and Tiamojat. For more details, please visit us in the Montajat showcase of Engormix, or our website www.montajat.biz

Elimination of infected flocks, and strict quarantine and biosecurity measures until eliminated completely. 

A preventive program against CCRD has been developed and tested successfully by Montajat, which alleviates any passive infection. In this program, following regimen is followed during the broiler life- cycle:

The prevention program reduces the cost of treatment, decreases FCR (clean and healthy villi), controls vertical and horizontal transmission, and enhances the profitability of the flock. Also, it adheres to meet the withdrawal time norms.