The EMPRES Transboundary Animal Disease Bulletin

 

The EMPRES Transboundary Animal Disease Bulletin no.5 - March 1998

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Contacting EMPRES

EMPRES e-mail address: empres-livestock@fao.org

 

1

FMD WARNING A variant strain of Foot-And-Mouth disease virus serotype A has spread In Asia and is a threat to other parts of Asia and Europe 

2

Alarming appearance of variants of Type A FMD virus 

2

A Pig adapted Type O FMD virus 

2

Significant strides against FMD in 1997 in Latin America 

2

RINDERPEST WARNING Sudan and Uganda react to rinderpest threat 

3

Rinderpest status in Afghanistan 

3

Subregional Workshop on the Surveillance of Rinderpest and the OIE pathway 

4

Summary PARC 1997 

4

Rinderpest virus lineages 

5

Epidemiological considerations for CBPP vaccination 

5

New introduction of CBPP in Burundi 

5

Update on African Swine Fever (ASF) in West Africa 

6

Rift Valley Fever and other Epidemics due to excessive rains in Eastern Africa 

8

Avian Influenza not found on mainland China 

8

A survey of the disease status of scavenging poultry in the Morogoro Region, Tanzania. 

8

Danish Network on Poultry Production and Health in Developing Countries 

9

Village chicken production systems in rural Africa and the relative significance of Newcastle Disease 

9

CENTAUR - Veterinary Biotechnology Network for Central and Eastern Europe 

9

RADISCON Update 

10

Planned Workshops for 1998 

10

Contributions from FAO Reference Laboratories and Collaborating Centres 

10

Communication with EMPRES 


 

FMD WARNING A variant strain of Foot-And-Mouth disease virus serotype A has spread In Asia and is a threat to other parts of Asia and Europe

In the December 1997 issue of The EMPRES Bulletin the FAO/OIE World Reference Laboratory (WRL) for Foot-and-Mouth Disease (FMD) reported that isolates of FMD virus, serotype A, received from Iran during 1996-97, were genetically and antigenically distinct from any other type A isolates in the WRL database.

In March of this year the WRL identified a series of type A strains among samples from suspected cases of FMD in Turkey during 1997 and 1998. When a comparison was made between five Turkey A isolates from 1997-98 and five isolates of the type A/Iran variant from 1996-98 both sets of viruses were found to be almost identical in the 1D (VP1) gene coding region (nucleotides 475-639). Furthermore, the Turkey type A isolates, like the type A/Iran variant, were found to be genetically different by almost 20% from any other type A isolates in the WRL database.

The Turkey type A isolates were collected from the provinces of Malatya in Eastern Anatolia and Kutayha in Western Anatolia indicating that the strain is widely distributed in that country.

Antigenic analyses have shown that the type A isolates from Iran and Turkey are distinct from all of the FMD virus strains which are commonly included in FMD vaccines. This indicates that current vaccines are not likely to protect against challenge by the variant. This conclusion is supported by observations in Turkey where disease has been seen in animals vaccinated with bivalent O/A vaccine in which the A component was strain A22 Mahmatli.

It can be concluded that the type A variant, first identified in Iran, has extended its geographical distribution into Asiatic Turkey and is now a threat to other countries in Asia and to Europe, especially those countries which are linked to Iran and Turkey by trade in livestock. In this regard small ruminants pose a particularly high risk since FMD in them is often clinically mild or even inapparent.

There is an urgent need for the development of vaccines incorporating antigenically suitable strains to control disease in countries where the type A variant is present and to prevent further spread. In this context the vaccine strains used in the FMD Buffer Zone in European Turkey should be reassessed and the strains stored in vaccine banks should be reviewed in the light of the emerging disease situation.

(Alex I Donaldson FAO/OIE WRL for FMD Institute for Animal Health Pirbright).
 

In the early 1950s a major FMD epidemic in Europe and the Near East, caused by the emergence of a new strain of Type A FMD (identified as sub-type A5), resulted in 870,000 outbreaks and losses estimated at US$ 600 million. Another episode of a new variant of type A virus was in the 1960s. In autumn 1964 a new situation developed in the Near East with the appearance in Iran of a new variant of the type A virus, which was classified later as sub-type A22. The A22 epidemic swept through most of the Near East from Afghanistan to Turkey and by mid-1965 it had reached Thrace. There is a serious risk that the earlier events could be repeated unless immediate steps are taken to contain the new variant. 

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Alarming appearance of variants of Type A FMD virus

During the last few years, the FAO/OIE World Reference Laboratory for FMD (WRL) has been monitoring the emergence and spread of strains of type A FMD virus in various regions of the world which are antigenically and biochemically distinct from each other and from strains previously recorded and stored in our database. In 1996 a new strain of type A was isolated from samples sent from Iran. This had a nucleotide sequence difference in the VP1 gene of over 20% from any other isolate previously received. It was also antigenically distinct and outside the immune cover provided by existing vaccine strains. This variant is still causing outbreaks, but currently restricted to Iran.

In 1997, a type A variant caused outbreaks in Peninsular Malaysia and Thailand. The nucleotide sequence of this variant suggested that it had evolved from type A strains circulating in the region, but the accumulated mutations in these new isolates were now sufficient to significantly change their antigenic characteristics, so that existing vaccine strains were no longer effective.

Strains of type A have also been causing widespread outbreaks in West Africa during 1996, 1997 and this year, and samples have been received by the WRL from Côte d'Ivoire, Ghana, Mali, Senegal and Mauritania. Although the strains are also over 20% different in their VP1 nucleotide sequences from contemporary type A strains from other regions, this reflects more the absence of organised FMD control programmes in the countries affected. Only now, when vaccination is being considered to help control the outbreaks, are regular samples being received by the WRL. It is probable that the virus has been circulating in West Africa for some time, and sequence changes have accumulated so that the strains are antigenically very different from any existing vaccine strains.

A fourth new type A variant has recently been isolated from samples received from Eritrea. Type A is a new introduction into Eritrea, and is also unlike others in the WRL database. Its closest relatives are the type A's from West Africa, from which it differs by over 17% in its VP1 sequence.

Antigenic variation has always been greatest within the A serotype of FMD virus, but the recent appearance of so many variants worldwide does cause concern, as any of these could suddenly expand its distribution.

(Contribution from Paul Kitching FAO/OIE World Reference Laboratory for FMD Pirbright, UK).

 

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A Pig adapted Type O FMD virus

A pig-adapted strain of type O FMD virus has been spreading in South East and East Asia, causing widespread and clinically severe outbreaks particularly in the intensive pig producing areas of Philippines, Taiwan Province of China, China Special Administrative Region of Hong Kong, and Vietnam.

When experimentally inoculated into two cattle one failed to respond, and the other only developed lesions at the sites of inoculation on the tongue (Dunn and Donaldson (1997), Veterinary Record, 141, 174-175). However, experimentally infected pigs developed severe clinical signs very rapidly and spread the disease to in-contact pigs. Further samples are requested by the World Reference Laboratory (WRL) from the region to monitor any further spread.

A single outbreak due to this strain was seen in a pig farm close to Moscow in 1995, and was probably caused by the feeding of material imported from Asia.

(Contribution from Paul Kitching FAO/OIE World Reference Laboratory for FMD Pirbright, UK)

 

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Significant strides against FMD in 1997 in Latin America

  • Brazil has applied to the OIE for FMD free status with vaccination for the southern states of Rio Grande do Sul and Santa Catarina.
  • Argentina and Paraguay have been declared free from FMD with vaccination by the OIE in May 1997 with the effect of an increase in meat orders from overseas markets. Argentina's national Animal Health Service opened a bio-secure exotic disease section in the Central laboratory for the diagnosis of FMD and other infectious diseases.

 

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RINDERPEST WARNING Sudan and Uganda react to rinderpest threat

The FAO World Reference Laboratory for Rinderpest has confirmed the diagnosis of rinderpest from two samples collected from within the south-eastern Sudan rinderpest endemic focus in March 1998. The virus has been sequenced and shown to belong to the African Phylogenetic Lineage 1 which has previously been associated with outbreaks in southern Sudan and the contiguous parts of Ethiopia, Kenya and Uganda. In view of livestock movement, especially between southern Sudan and Uganda, countries in the region have been warned by both the OAU/IBAR Pan African Rinderpest Campaign (PARC) and the EMPRES Programme to strengthen their rinderpest emergency preparedness.

The outbreak is suspected to involve Torit district of Eastern Equatoria State in southern Sudan. The area in question falls in zone D of epidemiological zones mapped recently by the Sudanese veterinary authorities. This area is bordering Uganda, Kenya and Ethiopia. It is characterised by security instability due to civil strife in the South and uncontrolled livestock movements. In response to the outbreak, the Sudanese authorities have imposed a strict control of any livestock movements north of zone D to minimise the risk of spread to the rinderpest free areas. In addition the veterinary authorities have mounted a field disease investigation campaign in an attempt to establish the exact location of the outbreak and have urged for complementary investigations to be undertaken in the contiguous parts of Ethiopia, Kenya and Uganda. Evidently support for rapid response with vaccination is also needed.

The Ugandan National Veterinary authorities, on their part, have announced the control of cross border movement of livestock and are mounting an emergency vaccination programme in the northern part of the country. This action is being supported by PARC and the EC as well as the FAO Technical Co-operation Programme through EMPRES.

Government authorities and NGOs operating in this eco-system are being urged by EMPRES and PARC to intensify efforts for both disease surveillance and rapid response vaccination in order to define and limit the extent of the outbreak, which has not been fully mapped. The objective should be to achieve immuno-sterilisation as soon as is practically possible in the high risk areas. Recent experience in southern Kenya and northern Tanzania has shown that this can readily be attained by two consecutive rounds of vaccination of all cattle of all ages within 6 months. In the rinderpest high risk, pastoral areas of southern Sudan, northern Uganda, north-western Kenya and south-western Ethiopia, NGOs and community-based animal health workers will have a vital role to play in both vaccination and surveillance. The thermostable rinderpest vaccine preparation would be the vaccine of choice.

 

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Rinderpest status in Afghanistan

In October 1995, Afghanistan experienced an outbreak of rinderpest in the southern Khost Province, bordering Pakistan. Subsequently, Dr. Paul Rossiter, FAO consultant, confirmed that the disease had been imported from the Punjab of Pakistan through the north-west Frontier Province. Within a week of confirmation of the outbreak, the UNDP Integrated Livestock Programme for Afghanistan acquired 50,000 doses to undertake a rinderpest vaccination campaign. EMPRES arranged the supply of rinderpest vaccine and laboratory assistance from the Pakistan Department of Veterinary Services.

However, vaccination coverage was low since an awareness campaign did not precede the vaccination campaign. Cattle owners had not fully appreciated the implications and risk of infection if livestock was not vaccinated.

Initially, veterinary personnel expected classical signs of rinderpest, which were often not evident. Consequently, many relatively mild cases of rinderpest were missed. This influenced the poor vaccination coverage even further.

Through a TCP project, FAO was able to provide funding to assist in activities necessary to contain the disease. An awareness campaign was initiated; national campaign co-ordinators were employed to assist with the campaign and surveillance before and after vaccination; and vaccine and equipment were purchased.

This TCP funding is now almost depleted leaving a possible danger that rinderpest surveillance will no longer be sustainable although, re-introduction of rinderpest from neighbouring Pakistan, where rinderpest is endemic, still remains a major threat.

Veterinary services in Pakistan have little influence in remote areas over the control of cross-border livestock movements to war-torn Afghanistan. The remaining TCP resources are being used to review the disease situation in Farah Province, in West Afghanistan, bordering Iran, and to commence a sero-survey in the Khost Province.

Recently, radio broadcasts in Iran summoned livestock owners to present herds to veterinary authorities. This alerted suspicion in the Afghan Programme that rinderpest epidemics might have been occurring in Iran. Dr. Mehraban, Senior Veterinarian to the Afghan Programme, and Iranian authorities clarified that livestock owners were summoned solely for the purpose of rinderpest sero-surveillance. The Afghan Programme applauds the commitment and protection beyond its western borders.

(T. J. Barker & A. Majok, FAO/UNDP Integrated Livestock Programme for Afghanistan).

 

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Subregional Workshop on the Surveillance of Rinderpest and the OIE pathway

The sub-regional workshop, which took place early December in Dakar, targeted rinderpest surveillance and the OIE pathway at managerial level of national disease surveillance programmes of West and Central Africa, within the Pan-African Rinderpest Campaign (PARC). Senegal, Guinea-Bissau, Chad, Niger, Nigeria, Cameroon, Benin, Togo, Ghana, Senegal, Mali, Mauritania and the Gambia were represented. The workshop was jointly sponsored and organised by IAEA, FAO EMPRES and OAU-IBAR/PARC.

The workshop clarified the OIE pathway with regard to disease surveillance and the countries represented confirmed their commitment to its adoption. Outbreak simulation exercises for West and Central Africa were carried out followed by presentations on contingency planning. These helped in identifying needs and constraints of disease surveillance at the national and at the regional level.

Although the ELISA technology for the laboratory diagnosis of rinderpest is operational in most of the countries, there is a need to strengthen all aspects of emergency preparedness. After cessation of vaccination against rinderpest in West and Central Africa the recognition, diagnosis and surveillance of rinderpest has become the most important component of PARC.

Simulation exercises showed a lack of preparedness for potential rinderpest outbreaks in most countries of the region. The concept of performance indicators for disease surveillance was presented during the workshop, which will be used to assess the efficiency of the national disease surveillance systems and their capability to detect rinderpest in case of new introduction.

Conclusions and Recommendations

  • Represented countries confirmed their commitment to the adoption of the OIE pathway and cessation of vaccination against rinderpest
  • Countries recognised the urgent need to strengthen preparedness for rinderpest outbreaks at national and at regional level
  • A series of workshops for the recognition, diagnosis and surveillance of rinderpest as part of emergency preparedness should be held at the national level
  • Diagnostic capabilities in differential diagnosis of rinderpest should be strengthened at the regional level and be established at the national veterinary laboratories in the longer term.
  • All measures should be taken to prevent the movement of rinderpest to West Africa from the remaining endemic areas in Eastern Africa by strengthening of the sanitary cordon and disease surveillance in the Central African Sanitary Cordon, while redoubling the effort to eradicate rinderpest from Eastern Africa
  • Communication networks should be established between the countries of the region
  • Disease surveillance should be clearly identified and implementation expedited within the national PARC projects
  • PARC should provide member countries with guidelines for accessing contingency funds and vaccine banks in emergencies
  • FAO, together with other international organisations, promote the need for structural adjustment programmes to sustain the veterinary services for emergency preparedness for transboundary animal diseases

 

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Summary PARC 1997

West and Central Africa have not reported rinderpest since 1988. Active surveillance for the disease will be introduced in many of these countries under the PARC/IAEA sero-monitoring network.

Some foci of infection seem to persist in parts of Eastern Africa, although limited confirmation of this is available for 1997. The situation in southern Sudan still needs clarification, while Ethiopia does not seem to be infected after cessation of vaccination and intense monitoring. The last epidemic of severe rinderpest in wildlife and mild rinderpest in cattle in Kenya in 1996 is still of concern. The four rinderpest outbreaks, which were confirmed from Tanzania in early 1997, are attributable to lineage 2 virus. Sero-surveillance in wildlife in Kenya has shown

  • buffalo yearlings in Tsavo are antibody negative
  • there is an absence of antibody to rinderpest in highly susceptible wildlife species in northern and north-eastern Kenya
  • antibody positive samples from older animals were probably infected in earlier epidemics
  • no antibodies to rinderpest were exhibited in young animals

(Extracted from PARC Newsletter December 1997).

 

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Rinderpest virus lineages

The use of molecular techniques, RT/PCR analysis, has enabled direct identification of these viruses, even when tissue samples are poorly preserved. DNA sequence analysis has improved greatly the knowledge of the epidemiology of morbilli viruses.

Two distinct rinderpest virus lineages seem to be co-circulating in Africa with a third lineage confined to Asia. The first African lineage has been circulating in border areas of Kenya, Uganda, Sudan and Ethiopia. The second African lineage was last found in Nigeria in 1983 and re-emerged in Tsavo National Park Kenya in 1994/95 after once having been isolated in the same regi-on from a giraffe in 1962. The virus is unlikely to have survived within the wildlife population since infection is normally devastating and extinguishes itself naturally. An unidentified host outside the Park is more likely to be the source. The molecular data also clearly shows that the outbreak probably did not originate from southern Sudan as formerly suspected.

(Extracted from FAO World Reference Laboratory for Rinderpest, Annual Report 1996-97 by T. Barrett et al. and M.A. Forsyth et al.).

 
 

African countries to have declared 'provisional freedom from rinderpest' are:
•Burkina Faso: 2 January 1998 •Mali: 19 December 1997 •Niger: 7 November 1997 •Ghana: 28 February 1997 •Côte d'Ivoire: 10 January 1997 •Senegal: 10 January 1997 •Guinea: 19 July 1996 •Togo: 19 July 1996 •Egypt: 26 July 1996 •Gambia 1990
 

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Epidemiological considerations for CBPP vaccination

Endemic CBPP has a complex epidemiological picture influenced by its pathogensis, different levels of immunity in healthy animals, varying virulence of field strains and the effect of vaccination campaigns.

Effect of vaccination on CBPP incidence in a population as recorded in Namibia

Cattle vaccinated during incubation or recovery may continue to shed organisms. Hence vaccination campaigns aimed at eradication should be planned over a 3 to 5 year period and antibiotic treatment of diseased animals discouraged.

Vaccination with T1-44 vaccine initially lowers the incidence but re-vaccination is required about six months later to bring immunity to an adequate level in a population. To maintain uniform population immunity annual CBPP vaccination should be carried out. As evident from the graph, the disease curve is not smooth and individual epidemics should be handled separately.

Eradication of CBPP requires high dedication and perseverance.

(Extracted from Epidemiological Update, Namibia by Roger Paskin).

 

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New introduction of CBPP in Burundi

Burundi has experienced a negative impact on its animal husbandry as a result of socio-political problems that commenced in 1993. On account of the civil war, livestock raids, numerous illicit transactions including illegal movements across national borders, CBPP has recently been introduced into the country. As of January 1997, disease has been detected in two provinces, Kirundo and Ngozi and has spread rapidly southwards. The extent of the damage has yet to be assessed. Traditionally, high density and sedentary livestock keeping is characteristic for Burundi. The displacement of animals out of this distinctive system has allowed entry of the disease.

Faced with the inability of the current veterinary structures to contain this problem, the government of Burundi requested FAO for technical assistance. A TCP project (TCP/BUR/8821: "Campaign de prophylaxie contre la péripneumonie contagieuse bovine et surveillance épidémiologique de la peste bovine") has been granted to assist Burundi. The project will cater for upgrading the field component of CBPP control, surveillance early warning capacity for both CBPP and rinderpest in the country. It will assist establishing a diagnostic unit in the Bujumbura Central Veterinary Laboratory to undertake routine serological screening for both diseases. The project will also supply the necessary vaccine doses to cover three consecutive CBPP vaccination rounds at 0, 3-6 and 12-18 months in the affected areas and assist in the organisation of the logistics.

Moreover, Burundi should request for participation in the programme of the OAU/IBAR on animal health issues. In this way, they will be able to consolidate eradication/control campaigns for CBPP and FMD, that are both present in the country and also, prevent potential entry of transboundary animal diseases.

 

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Update on African Swine Fever (ASF) in West Africa

The emergency TCP Projects for ASF control were approved for Benin, Cape Verde and Togo. TCP approval is expected for Nigeria. The regional TCP: "Enhancing emergency preparedness for African swine fever in West Africa" for Burkina Faso, Cameroon, Gambia, Ghana, Cote d’Ivoire, Guinea, Guinea-Bissau, Liberia and Senegal, also awaits approval.

The establishment of ASF virus in the West African ecosystem poses a great danger. However, So far, excavation of numerous warthog burrows in Benin did not yield ticks of the genus Ornithodoros, known to be involved in the maintenance cycle in Eastern and Southern Africa. O. Moubata has never been recorded in West Africa. The related O.erraticus has been found in Senegal and other Sahelian countries. Only hard ticks, Rhipicephalus cuspidatus, were collected from burrows and warthogs. Samples both from wild Suidae and ticks will be investigated further. Possible maintenance hosts of ASF in wild Suidae are warthogs (Phacocoerus africanus) and bush pigs (Potamochoreus porcus). These are known to be susceptible to ASF infection but resistant to disease.

Contact between free ranging village pigs and wild Suidae, in infected zones constitutes a risk of infection and consequent endemicity. Survival and maintenance of virus also occurs in certain African village pigs independent of wild Suidae and Ornithodoros ticks.

The origin of the present epizootic in West Africa is still considered to have been infected domestic pigs or their products from neighbouring countries.

ASF control in West Africa requires international co-operation and co-ordination for the formulation of a sub-regional programme of control and eradication.

Intensive clinical and epidemiological surveillance with efficient disease reporting at all levels and disease verification should be co-ordinated by a national committee. Emergency teams will have to be established through strengthened veterinary services.

ASF control, eradication and re-stocking should be supported by legislation. Increased public awareness, movement control and involvement of the public sector are also important.

 

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Rift Valley Fever and other Epidemics due to excessive rains in Eastern Africa

Although Rift Valley Fever is widely distributed in Africa, epidemics tend to occur in 5 to 20 year cycles affecting sheep, goats, cattle, domesticated Asian buffaloes, camels and humans. The climatic factors favouring its emergence are known to follow heavy and prolonged, often unseasonal, rainfall. In October to December 1997 and continuing into early 1998, an epizootic similar to the one in 1961-63 occurred in Eastern Africa. Infection rates appeared to be higher and the disease was more widespread than usual.

Remote sensing data indicated that suitable conditions for the explosive multiplication of mosquito vectors persisted over extensive areas of Kenya, southern Somalia, southern Ethiopia, eastern Uganda, southern Sudan and northern Tanzania

Kenya

RVF was identified principally in exotic breeds or crosses, of sheep and cattle throughout known epizootic areas in the highlands of Kenya, the Rift Valley Province, the Central Province and the Eastern Province adjacent to Central Province). Abortion was the most important sign of RVF in cattle and sheep. Neither abortions nor deaths were reported in cattle in the areas of North eastern Province.

In the southern and northern pastoral areas of the country and in Laikipia, sheep and goats have been severely affected.

Foot rot, bacterial arthritis, pneumonia, pasteurellosis, contagious pustular dermatitis, haemonchosis, infestations, capripox and caprine pleuropneumonia (CCPP) probably all contributed mortality and morbidity.

Extensive abortion storms was experienced amongst the camel herds, the principal effect of RVF infection in camels. Severe mortality has been observed in the camel herds following parapox infections.

Other insect borne virus diseases are likely to become important in the 1-2 years following these excessive rains. Lumpy skin disease has already been seen in Kenya, bluetongue, African horse sickness and Nairobi sheep disease have also become problems in certain areas. Ephemeral fever may also appear soon.

Abortion attributable to RVF may occur in wild ruminants, but this has not been observed. An unusual cluster of deaths was reported in gerenuk in Laikipia which may have been due to RVF.

Somalia

Some of the contiguous areas of NE Kenya with Somalia were found to be involved in the Kenya epizootics, depending on the extent of the rains. Virus activity in these ecological zones has been identified by high RVF antibody titres in camel sera following abortion storms occurring within weeks of the onset of heavy rains.

Investigations in North Eastern Somalia and on the border to the Ogaden region, Ethiopia, showed potential breeding sites for the Aedes mosquito which seed the epizootics of RVF to be unlikely. No animal disease component or human sera examination yielded evidence of RVF in the mountain regions of Sanaag or Erigavo.

There was no history of abortion or disease of any kind following the rains.

In camels disease associated with haemorrhage in the nose, mouth, intestines, lungs and serous surfaces was described and appeared to spread from herd to herd. Pasteurellosis may be one of the aetiological agents. Camel pox and parapox infections were also evident.

No outbreaks of abortion in camels, sheep nor goats following the rains in October and November of 1997 were noted.

Somalia

Amplification of RVF virus by mosquitoes in the southern regions of Somalia occurred associated with the flooding of the two rivers.

Huge loss of livestock with the majority of the mortality was due directly and indirectly to the effects of the flooding itself.

Lameness in small ruminants with septic arthritis in one or more joints reduced mobility resulting in animals gradually wasting away and dying from pneumonia or other causes such as Pasteurellosis. Parapox infections (contagious pustular dermatitis) caused losses in sheep, goats and camels. Very severe anaemia associated with worm infestation was causing mortality. Contagious caprine pleuropneumonia was common. The huge attack rates by biting flies caused camels to self-inflict injuries in the chest and abdominal areas.

Abortions were consistently reported in camels and also in goats. Cattle were little affected by the flood conditions and no abortions were reported in these animals. The camel and goat abortions may well have been due to RVF.

Investigations in camels and small ruminants confirmed that RVF virus activity had been taking place in S Somalia.

A ban on all shipments of sheep goats and other livestock from Somalia and neighbouring countries to Saudi Arabia came into force on 10 February 1998. Exports of sheep and goats fell dramatically by about 40%.

Sudan

The Equatoria Province of the Sudan has many ecological zones in which RVF is likely to be endemic. RVF virus is known to have occurred in the past in the country both as a disease problem and as a cryptic vector/ruminant host cycle without any manifestation of disease.

No suggestion of clinical RVF in animals was reported from the south of the Sudan although ecologically this area would be expected to support RVF vectors.

Tanzania

RVF has been recognised in the exotic breeds of cattle and sheep, which presents with epidemics of abortion with some mortality in young animals. Drops in milk yield, associated with fever, are additional presenting signs in dairy herds together with abortions. Exotic and exotic cross cattle in Tanzania, notably in West Kilimanjaro-Arusha, Moshi, Iringa, Loliondo, Mpwapwa, Morogoro, and Mufindi districts have been effected by RVF.

Disease in zebu and boran animals kept in the same eco-systems as the exotic breeds have shown no clinical signs of RVF.

East Coast Fever, bluetongue and Nairobi sheep disease have also been confirmed in this area. The latter causes very high mortality rates in indigenous small ruminants (50-90%) and abortion is a feature of the infection. Foot problems in sheep and goats in the persistently wet areas of Masailand complicated the clinical features.

Deaths in camels with diarrhoea appeared more likely to be due to Pasteurellosis.

Orf, and tick infestations and haemonchosis have been identified

There was little evidence of any human disease which might have been attributed to RVF in the villages after testing since sera were found to be negative for RVF IgM antibody.

No reports were received from Mwanza, Shinyanga and the Mara region. In the Serengeti, in Seronera, Rubanda, Mongeta and Nata areas, cattle showed corneal opacity, laminitis, lymphadenopathy, weakness and then death. Tick borne disease and trypanosomiasis were commonly diagnosed. The sheep and goats were losing weight with some deaths associated with foot lesions and pneumonia, helminthiasis, anaemia and CCPP. No abortions were reported here and the dead sheep and goats did not show any abnormality of the liver.

In Tanga, Korogwe, Lushoto near Taita areas, serious abortion storms in dairy cattle due to RVF were evident during December and January, although no human cases were reported.

Uganda

The virus is known to be present throughout much of the country, notably the higher rainfall forest and derived forest and wet savannah zones. Clinical RVF has not been reported from Zebu cattle nor indigenous sheep and goats.

Rwanda

With reduced numbers of exotic cattle populations, indicator hosts for RVF have been virtually eliminated hence no signs of manifestation of RVF in zebu or Sang breeds and neither in sheep and goats.

Following the peak in the RVF epidemic in Eastern Africa, the frequency of reports of disease is declining rapidly however a possible flare up after the seasonal rains in March and April should not be discarded.

The RVF epidemic has suggested a need to review the current OIE Guidelines for RVF Export/Import Trade and the OIE International Animal Health Code on the basis of epidemiology, pathogenesis and risk assessment for RVF.

(Extracted from the Field Mission Report on RVF epidemic 1997-1998 in East Africa, north eastern and north western Somalia by G. Davies et al.)

This epidemic of RVF could have resulted in establishment of infection outside the normal endemic foci and result in increased viral activity in subsequent rainy seasons. The risk is expected to be highest if there is a recurrence of the abnormal weather conditions experienced recently, related to an El Niño event. Even if normal weather patterns return some recurrence of RVF is to be expected in the affected areas in the next few years. Countries in the Greater Horn of Africa would be wise to prepare for such an eventuality.

Epidemics of RVF occur at long irregular intervals of many years and outbreaks tend to occur simultaneously across an extensive area. This makes it difficult to advocate, and justify the expense of, repeated prophylactic vaccination of susceptible livestock species during the long inter-epidemic periods. The recent events underline the fact that the threat of RVF epidemics can only be handled appropriately by an early warning and early reaction system for eastern Africa initially and eventually sub-Saharan Africa. This has long been promoted by those working closely with the disease in eastern Africa who have shown that analysis of remote sensing data within a geographic information system, combined with surveillance for renewed virus activity, offers the prospect of predicting RVF virus activity and the emergence of epidemics. Prophylactic immunisation of livestock could then be applied in time to avert the most serious consequences. Additional safeguards using modern developments in vector control, which could include chemical control of vectors by, for example, ultra-low volume spraying and application of systemic insecticides to target species, and biological control methods could be established. Effective early warning also requires a strengthening of national disease surveillance capability.

 

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Avian Influenza not found on mainland China

The Ministry of Agriculture announced in Beijing that Avian Influenza has not been found on the mainland of China and therefore transport of live chickens to Hong Kong resumed on 7 February 1998. Investigation of 1500 blood samples from Shenzhen, Guangzhou, Nanhai and Xinxing showed no evidence of the presence of H5N1 virus. WHO experts confirmed the above and also the quality of monitoring technology and infrastructure for Avian Influenza in Guangdong Province.

Strengthened quarantine inspection of live chickens and other poultry being exported to Hong Kong, development of virus tests for Avian Influenza and increased sanitary measures on exporting chicken farms should prevent the occurrence of another epidemic.

(Extracted from the Chinese People's Daily, 25 Jan 1998).

 

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A survey of the disease status of scavenging poultry in the Morogoro Region, Tanzania.

In Tanzania there are about 20 million scavenging chickens owned by small holders. These village chicken scavenge on offal, insects and seeds to cover daily needs. Studies have shown that within the first year of hatching the mortality may reach 80-90%.

The chicken population under study comprised flocks of rural, scavenging poultry in the Morogoro Region, Tanzania. Sampling was performed twice from February to March 1995 (wet season) and from October to November 1995 (dry season). Blood samples were taken as well as clinical and post-mortem examinations were performed on all animals. In total, 600 adult chickens were examined.

The serum samples were tested for the following antibodies (prevalences indicated in brackets) Newcastle disease (1% (dry season) & 7.3% (wet season), Infectious Laryngotracheitis (35.3% & 58.3%), Chicken Anaemia Agent (75% & 75%), Gumboro disease (36% & 42.3%) Salmonella gallinarum/pullorum (52.7% & 4.3%) and Salmonlla spp. (1% & 2%).

All chickens were found to harbour one or several species of helminths from a range of 29 different helminth species. The most prevalent rank as follows Tetrameres americana, Ascaridia galli, Heterakis gallinarum, Allodapa suctoria, Capillaria obsignata, Raillietina echinobothrida, Raillietina tetragona, Hymenolepis carioca, Hymenolepis cantaniana and Amoebotaenia cuneata.

Thirty five percent of the birds, in the dry season, and 65% in the wet season were infested with ectoparasites. These were Menocanthus stramineus, Cuclotogaster heterographus, Dermanyssus gallinae and Cnemidocoptes mutans.

This study shows a complex interaction of a number of diseases. For example, the low antibody titre to Newcastle Disease virus may show the vulnerability of the population to new epidemics. Further investigations are required to determine the individual and combined effect of other diseases on productivity and mortality.

(Full findings to be published in Preventive Veterinary Medicine by Dr Anders Permin, section for Parasitology, The Royal Veterinary and Agricultural University Copenhagen, Denmark. Email: ape@kvl.dk).

 

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Danish Network on Poultry Production and Health in Developing Countries

A research network based on the above study and other related current projects being carried out at The Royal Veterinary and Agricultural University Copenhagen and The Danish Institute for Agricultural Science, Foulum has formed a basis for a research network entitled "Poultry Production and Health in Developing Countries".

The main objectives of the Network are

  • to establish and maintain an international research base on rural scavenging poultry production and related topics
  • to train technical staff from Denmark and developing countries in disciplines related to traditional and semi-scavenging poultry production
  • to establish and maintain a human resource base for project support

At present, the network has multidisciplinary activities in Tanzania, Nicaragua, Zambia, Zimbabwe, Ghana, Indonesia and Bangladesh.

The network is currently planning to implement a model for the development of rural poultry in Vietnam, India, Uganda, Tanzania and Bangladesh, based on a DANIDA-IFAD project in Bangladesh.

For further information on the network pls. contact Prof. Peter Nansen, e-mail: poultry@kvl.dk

 

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Village chicken production systems in rural Africa and the relative significance of Newcastle Disease

Newcastle disease (ND) is known to be the most devastating disease in village chickens in rural Africa.

One of the objectives of the 1994-1995 André Mayer Research Fellowship was to assess the relative significance of ND on African village chicken production systems. A parallel pilot scheme in The Gambia and Ethiopia assessed the heat-stable orally administered ND vaccine in village chickens.

Village chickens are predominantly indigenous domestic fowl. The rural poultry sector does not normally offer a regular health programme. Shelter is sometimes provided, but scavenging covers the main nutritional requirements.

Major factors associated with the transmission of ND in village chickens are

  • exposure to wild fauna
  • multi-age flocks and frequent introduction of susceptible hatches
  • exchange of live chickens and products
  • human movement between households or villages

Bird to bird contact seems to be the most important mode of ND transmission in tropical or sub-tropical production systems, since airborne spread of the virus requires large numbers of chickens to generate sufficient dense aerosol.

The use of thermostable ND V4 has been introduced on a trial basis in a number of countries. Appropriate carriers for the V4 vaccine has been reported to be cooked rice, millet, sunflower, finger millet and sorghum. On the other hand, barley gave poor results as a vaccine carrier. Properties of crushed and cooked maize as a carrier ranked between the former and barley.

V4 vaccine administered orally seems to be the most cost effective of ND vaccines. A TCP will start a second phase this year to include further testing of the commercial NDV4 vaccine with foodstuff for oral administration. The results should support findings from Zimbabwe, Ethiopia and Zambia. Co-ordinated research and development in handling and administration of the vaccine is necessary.

In Zambia the vaccine has only been applied intraocularly under limited experimental conditions. Results obtained indicated necessity of careful recommendation of this vaccine for immunisation of poultry only when applicable as a supplementary scheme. The thermostability of the vaccine and its shelf-life has still to be confirmed. The vaccine can only supplement poultry immunisation at country level.

The similar I 2 vaccine which was made available by the University of Queensland, Brisbane, Australia can be locally produced by developing countries laboratories in embryonated eggs. However, if SPF eggs are not available use of microbiologically contaminated eggs could increase the risk of unwanted spread of adventitious pathogens. The field applicability of the I 2 vaccine is still to be evaluated.

The study in Africa on feed based vaccines (NDV4 and I 2), the socio-economical impact of rural poultry production and will be concluded through field studies.

The impact of other priority diseases of poultry on productivity will also be assessed to create a poultry health/breeding package for small holders farmers.

The FAO appreciates the involvement of the AGE (Joint FAO/IAEA Division in Vienna) and other bilateral aid from DANIDA, The Royal Veterinary and Agricultural University, Copenhagen, Denmark, Veterinary Faculty, University of Harare and NGOs. Community participation is also important in the development of sustainable ND control programmes.

(Compiled from Village Chicken Production Systems in Rural Africa- Household Food Security And Gender Focus by Aichi J. Kitalyi).

 

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CENTAUR - Veterinary Biotechnology Network for Central and Eastern Europe

FAO assisted in establishing a Veterinary Biotechnology Network for Central and Eastern Europe aimed at upgrading laboratory diagnosis for infectious diseases of livestock and veterinary vaccine standards to achieve full compatibility with the OIE and EU standards in Europe. A computerised e-mail network has been established under the FAO Technical Co-operation Project (1995-97) for Czech Republic, Hungary, Slovakia and Poland.

Five workshops took place in Budapest, Pulawy, Brno and Warsaw. National Project Co-ordinators were trained in leading research institutes and over 120 scientists underwent training for trainers.

CENTAUR has over 160 members linked through an electronic discussion group. The network includes European Veterinary Research Institutes, which should expand internationally. The network should progress into a support network for training, biotechnology and epidemiology development, complementary to activities of the European Commission for the control of Foot and Mouth Disease.

The CENTAUR newsletter Flash Info is an electronic journal, which can be accessed free of charge. For subscription and further information please contact Prof. Karel Hruska. Email: kahr@uvvel.anet.cz.

Ten issues are already available for 1998 at the following internet address: http://www.clark.cz/vri/biotech.html.

 

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RADISCON Update

In-country communications training workshops have already taken place in Morocco, Ethiopia, Kuwait, Algeria, Tunisia, Mali, Chad, Niger, Sudan and Turkey to initiate the process of strengthening individual National Animal Disease Surveillance Systems (NADSS). These systems are seen as being a combination of active and passive surveillance mechanisms and will, in the future, provide the core RADISCON activity at national level. This programme will continue into 1998-1999.

Algeria, Bahrain, Chad, Djibouti, Egypt, Eritrea, Ethiopia, Iran, Mali, Mauritania, Morocco, Niger, Oman, Sudan, Syria, Tunisia and Yemen have already been connected to the internet/email as a result of RADISCON activity while Palestine awaits connection. Israel, Libya, Turkey and Saudi Arabia have internet/email facilities without requiring RADISCON assistance.

The second steering committee met in Agadir, Morocco on 30-31 March 1998. The full coverage its outcome will be published in NEWS@RADISCON and the next bulletin.

As of June the RADISCON bulletin, will be included in the EMPRES Transboundary Animal Disease Bulletin.

 

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Planned Workshops for 1998
 

Ad hoc Working Group on CBPP  Rome, July 
EMPRES Technical Consultation  Rome, 28-30 Sept 
EMPRES Expert Consultation  Rome, 1-2 October 
Impact of disease on livestock trade in the Middle East (RADISCON)  Cairo, October 
Joint EMPRES/FAO IAEA Workshop on Emergency preparedness contingency planning for Transboundary Animal Diseases for Southern Africa  Harare, July 
Joint EMPRES/FAO IAEA Workshop on Emergency preparedness contingency planning for Transboundary Animal Diseases for Middle Asia  Tashkent, October 
Regional ASF Workshop  Togo, May 

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Contributions from FAO Reference Laboratories and Collaborating Centres

Rinderpest and PPR Report

No diagnostic samples for RP and PPR were submitted in January or February 1998.
 

Country  Date  Animal species  Result 
Sudan  3/1998  bovine  Rinderpest African lineage 1 

FMD Report January and February 1998
 

Country 

Animal species

Virus type 
 
Cambodia  porcine 

 
Cambodia  bovine 

 
Iran  bovine 

NVD 

Senegal  bovine 

NVD 

Senegal  caprine   

NVD 

China (Taiwan Province of China)  porcine 

SVD 

China (Taiwan Province of China)  NK   

SVD NVD 

Uganda  bovine   

NVD 

Total number of samples 75

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 Communication with EMPRES FAO (Rome)