Dr. Jonathan G. Bell
agree with Professor Spradbrow that the control of Newcastle disease is the key to the science of village chicken production and an indispensable condition for other interventions. I would like to thank him for his excellent review on thermostable vaccines.

I was interested to read of the non-conventional extension approaches. I wonder whether it would be possible to download the vaccination song so that we could all hear it?

Dr. Anders Permin
I agree with Professor Spradbrow that the control of Newcastle disease is necessary and important, but I would also like to attract the attention to other diseases. To my knowledge no studies have followed larger rural chicken populations for longer periods and simply done post mortems. This means that in fact we do not know what diseases are causing the high mortality in rural chickens. Newcastle disease (ND) is one of them, but the high mortality in chicks up to 3 months of age is not explained by ND only. Here we might be talking about bacterial and parasitic diseases. Studies in Tanzania and Nicaragua, where the chickens were immunized against Newcastle disease (not published yet), have indicated that the mortality is still high. Again this supports the fact that ND is not the only disease in rural chickens.

Back

Prof. Madundo M. A. Mtambo
First of all I would like to commend Prof. Spradbrow for his nice review on thermostable Newcastle disease (ND) vaccine in village chickens. I agree that thermostable vaccines are important in village conditions because of poor cold chain facilities. It is true that control of ND is essential since the disease may wipe out whole flocks during outbreaks. Nevertheless, our recent findings indicate that very high mortalities occur in chicks up to 6 weeks of age but the main cause has never been determined. Thus I agree with Dr. Anders Permin that the control of ND should go hand in hand with the control of other chicken diseases. Studies to establish the major causes of chick mortalities should be established so as to devise appropriate control measures of chicken diseases in village situations.

Back

Tadelle Dessie
I am totally in agreement with Professor Spradbrow that the control of Newcastle disease is necessary and important, but I am also attracted with the ideas of Dr. Anders Permin who underlines that the need of attention to other diseases.

According to the survey conducted by Tadelle and Ogle (1996) in three villages in the highlands of Ethiopia, disease was cited as the most important problem by most of members of the community with whom it was discussed, reducing both the number and productivity of the birds. Some farmers have given up rearing poultry because of an increase in disease problems after villagization (i.e. resettlement in villages) (1984-86), because of the higher level of contact between birds in the more densely populated areas facilitated the spread of diseases from flock to flock.

The close contact of different flocks from different households thereby facilitated transmission of communicable diseases, in addition to the problem of increased competition for the limited feed resources, which is the Scavenging Feed Resource Base (SFRB). The relationship between disease and flock density is apparent in the rural areas and some farmers in non-villagized areas have not had any experience of recurrent disease outbreaks, and consider that their birds are more vigorous and productive than the flocks in the larger villages (my personal observation).

The general feeling of the villagers is that the problem is getting worse and many people said that they had not encountered such problems prior to their resettlement. The symptoms of the common diseases as perceived by the community in the three villages are loss of appetite, reduction in drinking and eating, watery and yellowish droppings, paralysis and, consequently, death. This disease entity, which is probably Newcastle disease, is acute, lasting for only 3-5 days, and usually results in the death of the whole flock because transmission is very rapid. Newcastle disease is the most important disease in rural poultry production in the tropics.At this point I have a question to all participants, is this disease entity only ND or is there other diseases in cover of ND or is that a complication of different diseases at the same time and place? Because I had a bad experience of very high mortality even after vaccinating the whole flock in the village for ND.

The other problem is the prevailing of this high mortality of local birds under on-station and confinement conditions after they were vaccinated against "all" important poultry diseases in the area. This condition was reported at least three times from different parts of the country in different research stations and by different researchers. In six months time I am also planning to collect eggs from different parts of the country and start a new study on "Identification, characterization and evaluation of different strains of local birds for egg and meat production potentials in Ethiopia" (that is for my PhD), and I am worried about the problem I mentioned earlier. At this point I badly need ideas of all the experienced researchers in the area of rural poultry production to control this high mortality observed in local birds under confinement.

Back

Dr. Jonathan G. Bell
This is a reply to comment 4 on free communication 10 by Tadelle Dessie.
It is of course normal that there should be an increase in disease in the chicken flocks when nomads become sedentary and the birds are kept in closer confinement to each other. It is the same phenomenon that we see in the transition from village chickens to industrialised ones, but probably more intense. The disease you describe certainly sound like ND. If you do autopsies on the birds, you can see if they have haemorrhages on the proventriculus. This is extremely suggestive of ND in the absence of vaccination, although it does not prove it.

In the village where you vaccinated the whole flock:
- What vaccine was used?
- What administration route was used?
- How was the vaccine transported?
- Was it kept cold?
- How long after vaccination did the disease occur?
- Were antibodies to ND measured after vaccination?
- If so what were the titres?

The answers to these questions could give us an idea whether what happened was a failure in vaccination or another disease, which seem to me to be the two possibilities.

Parasites, Gumboro disease, mycoplasma and bacterial infections can complicate ND and turn an infection by an avirulent strain like Lasota into a pathogenic infection. In general, ND is a very acute disease, and the virulent strains that are prevalent in Africa are quite sufficient to kill all the chickens on their own. In this case the presence of the secondary infections is not relevant.

If it is another disease, one possibility might be fowl typhoid. It would be quite easy to answer the question definitively in the field by taking blood samples to measure antibodies against ND, doing autopsies, and taking bacteriological and possibly virological samples.

A lot of people doing zootechnical studies on African village poultry have had the problem of losing much of their stock through diseases, which is of course exacerbated by bringing birds together in confinement. However, a rigorous vaccination programme against ND, and some biosecurity measures including disinfection, etc., should go a long way towards controlling it.

Back

Dr. Robyn G. Alders
In response to Tadelle Dessie•s question regarding whether mortalities in village chicken flocks are due to Newcastle disease (ND) only, it is my opinion that there are a range of diseases that occur in village flocks. But I would qualify my response by saying that until villagers are sure that their chickens will not die regularly and in large numbers from ND, it is unlikely that they will be willing to make the necessary investments required to control these other diseases.

Regular outbreaks of ND probably help to interrupt the cycle of other diseases. With the control of ND, further research will be required to diagnose and rank other problems (diseases, nutrition, etc.). Coming up with cost-effective and appropriate solutions to these problems will keep us busy for some time.

Nutrition is clearly an area that requires more research, especially that of young chicks. Cost-efficient ways of providing supplementary feed to young chicks will almost certainly improve their survival rate and their response to vaccination.

I have enjoyed participating in this electronic conference and would like to take this opportunity to thank Dr. Guñye and co-workers as well as the FAO for facilitating this venture.

Back

Prof. P. B. Spradbrow
Thanks for the comments.

Of course there are other infectious diseases affecting village poultry. The studies in which they become obvious are those that involve observations on flocks vaccinated against Newcastle disease. To a large extent these are over future flocks, not our current flocks. These are our future problems, not our current problems. Studies in vaccinated flocks, such as those of Anders Permin in Tanzania or of the GTZ group in Thailand show us that Newcastle disease will not be the last of our problems. Our present focus must be on the diseases that kill chickens, and that kill them in large numbers. If Newcastle disease is uncontrolled, other diseases are eclipsed. I expect that the next urgent problems will also be acute, fatal diseases. My guesses would be fowl cholera, infectious bursal disease, salmonellosis, fowl pox and leucocytozoonosis in some areas.

The other current pressing problem is the massive losses that occur during brooding. The causes have yet to be specified. One problem is that the dead chicks are not found or not examined. They go to the "lost" or "disappeared" columns on surveys, and we know that these columns are essential in collecting village poultry data. However when workers intervene with provision of creep feeding and shelter, these brooding losses are greatly reduced. This suggests that the brooding losses are associated with starvation, exposure and predation and could be controlled by improved husbandry. Villagers seem unwilling to make these changes while infectious disease will deprive them of their increased flock after brooding. Our current extension objectives target both Newcastle disease prevention (not only vaccination) and improved husbandry to reduce brooding losses.

The innovative extension methods that I mentioned derive from the enterprise of Dr. Robyn Alders in Mozambique. We must ask her to try to make a video of the vaccination play. The vaccination song has not been performed professionally in English although there was an informal premiere by an ad-hoc 40-voice choir at a recent meeting in Tune, Denmark. The English translation is attached. The recorded version is performed in Portuguese, Changana, Nyanja, Sena and Macua. This electronic Luddite was not aware that songs could be put on websites. A cassette is on its way to Rome (by conventional mail). All this superb technology in some fields, and we still have problems vaccinating village chickens!

On a recent visit to Vietnam I spoke with colleagues about a possible version of the vaccine play for a puppet theatre. This might be a culturally appropriate medium in some other Asian countries as well. Robyn Alders has suggested utilising the talking drums in western Africa. FAO at one time had a series of projection slides, I think for use in Bangladesh. Any other suggestions? Vaccination kites? Vaccination dances?

English translation of the vaccination song prepared by The Association of Mozambican Musicians:

NEWCASTLE DISEASE

Lyric
The chickens I’d bred have died from sickness
The ritual chicken is dead
The rough sheep* chicken is also dead
Even the one I borrowed from neighbours died.

Chorus
What should I do?
In this hunger season?
What to do folks?

Dialogue
"Nooh. What ...... this is a bad omen to my ancestors."
"What’s wrong neighbour?"
"See my chickens are dying"
"How did they die?"
"Well, I don’t know. But they start like getting cold. Then they look like they’re wearing a coat and sleepy, then die."
"That’s a chicken disease called Newcastle"
"Pity me. I’m in deep trouble. What should I do?"
"Go to Rural Extension. They will give you vaccine to apply in the eyes or in the water they drink. They won’t die any longer."
"I see. But I don’t know the place."
"I will take you there"
"How kind. Let’s go."

Lyrics by Hortencio Langa and Wizzie Masuke.
Arranged by Wizzie Masuke in 3 idioms; Xangaan, Sena, Portuguese.
Translated by Ali Faki in Macua.
Music by Hortencio Langa.

* A term referring to chickens with the frizzle feather gene.

The recorded version features vocalists Hortencio Langa, Wizzie Masuke, Elidio Manica and Ali Faki and instrumentalists Hortencia Langa, Celso Paco and Manuel de Jesus.

Back

Tadelle Dessie
These are answers to Dr. Bell•s questions (see comment 5 on free communication 10).

In the village where I vaccinated the whole flock:
- What vaccine was used? It was La Sota
- What administration route was used? Drinking water
- How was the vaccine transported? Using thermoflask
- Was it kept cold? Yes
- How long after vaccination did the disease occur? It was after 5 to 6 days
- Were antibodies to ND measured after vaccination? I did not measure it
- If so what were the titres? No

Back

Dr. Jonathan G. Bell
With reference to Tadelle Dessie•s reply to my questions regarding ND vaccination in Ethiopia (see comment 8 on free communication 10), the fact that the disease occurred only 5 to 6 days after vaccination suggests that it was indeed ND. The incubation period for ND is about 4 days. That means that the chickens would have been infected only one day after vaccination, when the vaccine would not yet have had any immunoprotective effect.

If there are birds in the flock that are immunologically naive with respect to ND, La Sota vaccine is a relatively virulent one to use. It could cause vaccinal reactions, especially if there were concurrent mycoplasma and bacterial infections. This is all the more true in a village population, which is necessarily a multi-aged one including young chicks. La Sota is not used for a first vaccination in industrial poultry. A village population could already have sufficient antibody levels to allow effective use of it, but you can•t be sure of this - there are situations when the chickens have no antibodies against NDV.

Back