Avian Mycoplasma Myths

Other myths are emerging.
1) ts-11 only works to 40 weeks (of age or after vaccination). This is a misunderstanding of the seroconversion that often takes place after the peak of lay in vaccinated flocks. Studies on these flocks don't find wild strains and there is no production problems or clinical signs. They only thing they seem to be suffering is antibiotic deficiency syndrome. See Barbour et al., 2000 Poult Sci 79:1730-1735 for a nice example of protection at 57 weeks.
2) There have been no reports of resistance to tylosin in MG etc. This is wrong. ts-11 was developed because tylosin stopped working in Australia in the 1980s and this and other examples are well reported in the literature. Same goes for nearly every other antibiotic for MG and MS.

Good article, Dr. Morrow.
What do you think of vaccination in an infected environment? 
Thank you.

Dr. Chris,

Good write up on myth of Avian Mycoplasmosis!
Since most of the antibiotics available in our region have become resistance to MG & MS, would vaccination become the only solution to MG & MS? What to do in case of peep/clutch of chicks are already under incubation with MG or MS?

G.K.Dahal
Kathmandu, Nepal.

Vaccination in an infected environment

All vaccines take a little while for the onset of useful immunity (save non specific protection from mechanisms like gamma interferon in viral infections). Mareks vaccination becomes more effective with the current vaccines if challenge can be delayed a couple of weeks.
Live Mycoplasma vaccines also take 3-5 weeks to generate immunity and challenge needs to be minimized before this time. Also, we don't think these vaccines can work below 21 days of age (something perhaps correlated with a specific T-cell subset appearing in the thymus).
So if you have a multiage farm then it is better to move the rearing to another farm (perhaps 2km from all other infected farms). The birds only have to be here till 8 weeks of age - it could be in an industrial park or apartment block. Biosecurity is also needed with staff movements. Have dedicated staff or visit these farms first thing in the day and have clean clothes and maybe shower in.
Vaccination of flocks that might have vertical contamination. Well in the long term tell the supplier to vaccinate the flocks when they are negative (on delivery from breeding programmes in the first world) but we have also had some success with antibiotics before vaccination. The aim is to keep the mycoplasma in the infected birds from spreading to the rest of the flock.

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Replacement stock from positive parents

Antimycoplasmal antibiotics in first week, different antibiotic in second week in water and then stop 4 days before vaccination
No LaSota or stronger NDV vaccine within 14 days of live mycoplasma
Vaccinate with MG ts-11 and MS MSH at 21 days (as early as possible)
No antimycoplasmal antibiotics after vaccination.
For necrotic enteritis use amoxycillin or other penicillin.
If you have CRD after this time
Review antibiotics being used
Look at possible sources of potent early horizontal challenge (try to implement biosecurity till 5 weeks after vaccination.
Encourage supplier to use these vaccines

In case of high titers (i.e > 12000 mean titer) for Ms with Elisa technique for a non vaccinated flock (Layer Breeder) at age 50 weeks, is it confirmative or do we have to proceed to another test?

Could you comment on nasty production drop in layers after lasota vaccinations? Even despite preliminary antibiotic regimen can be embarrassing. Can you advise?

Very useful information for me.

Thanks, Dr. Chris Morrow.

We have been examining vaccinated flocks by DIVA PCR and culture recently in Asia. Here we can not find the MG and MS live vaccines in flocks that have had anti-mycoplasmal antibiotics. We typically find field strains (we suspect they are resistant to antibiotics). The vaccine strains are sensitive to all anti-mycoplasmal antibiotics (even quinolones like enrofloxacin) even if local field strains are not (Enrofloxacin has a poor record in recent years in Asia for mycoplasma control and this is being confirmed by our MIC testing of asian strains). So if you are continuing to use antibiotics after vaccination you are probably wasting your money on the vaccine and if the challenge is by a resistant field strain you are probably wasting your money on the antibiotic but also putting pressure on antimicrobial resistance development with no benefit.

Good article to know more about MS. This Glass top/EAA should be looked at broad end or narrow end of the egg?

I want to know more sir, please. From India.

Dear Dr. Chris Morrow.

I use ts11 vacine in the field to follow the procedure of properties. My birds are broiler breeder. We use ts11 vaccin at age 28 days. If result ELISA MG with mean titer range of 1000 to 2000 and % positive 50%, what is save to my birds of challange MG field infection. Please give me suggestions on what to do.

Tylvalosin tartrate is a new third-generation macrolide with 16-membered lactone antibiotics in poultry and obtained from tylosin by the change of 3-acetyl-40-isovaleryl group to be acetyl isovaleryl tylosin tartrate which is the best effective on Avian mycoplasmosis and mildly necrotic enteritis in Poultry and chicken.