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== Introduction ==

== Introduction ==

The condition is caused by a '''[[:Category:Morbilliviruses|morbillivirus]]''' of the family [[:Category:Paramyxoviridae|paramoxyviridae]]. The infective agent was first considered a variant of [[Rinderpest|rinderpest virus]] adapted to small ruminants, but was later shown to be '''antigenically<ref> Gibbs, E. P. J., Taylor, W. P., Lawman, M. J. P., Bryant, J (1979) '''Classification of peste des petits ruminants virus as the fourth member of the genus Morbillivirus'''. Intervirology, 11(5):268-274</ref> and genetically distinct'''.<ref>Diallo, A., Barrett, T., Barbron, M., Subbarao, S. M., Taylor, W. P (1989) '''Differentiation of rinderpest and peste des petits ruminants viruses using specific cDNA clones'''. J Virological Methods, 23(2):127-136; 24</ref>

The condition is caused by a '''[[:Category:Morbilliviruses|morbillivirus]]''' of the family [[:Category:Paramyxoviridae|paramoxyviridae]]. The infective agent was first considered a variant of [[Rinderpest|rinderpest virus]] adapted to small ruminants, but was later shown to be '''antigenically<ref> Gibbs, E. P. J., Taylor, W. P., Lawman, M. J. P., Bryant, J (1979) '''Classification of peste des petits ruminants virus as the fourth member of the genus Morbillivirus'''. ''Intervirology'', 11(5):268-274</ref> and genetically distinct'''.<ref>Diallo, A., Barrett, T., Barbron, M., Subbarao, S. M., Taylor, W. P (1989) '''Differentiation of rinderpest and peste des petits ruminants viruses using specific cDNA clones'''. ''J Virological Methods'', 23(2):127-136; 24</ref>

Recognition of PPR as a problem has increased in the 1990s, partly as a result of surveillance activities of the [http://www.fao.org/ag/againfo/programmes/en/grep/home.html '''global rinderpest eradication programme (GREP)'''], but also by the capacity of the infection to invade disease-free countries. The presence of infection restricts international trade in livestock and livestock products from infected countries, and is usually associated with ongoing severe economic losses.

Recognition of PPR as a problem has increased in the 1990s, partly as a result of surveillance activities of the [http://www.fao.org/ag/againfo/programmes/en/grep/home.html '''global rinderpest eradication programme (GREP)'''], but also by the capacity of the infection to invade disease-free countries. The presence of infection restricts international trade in livestock and livestock products from infected countries, and is usually associated with ongoing severe economic losses.

Because colostral antibody protects young animals, in endemic areas most disease occurs in animals after waning of colostral immunity, from '''4 months to 2 years of age'''. Mortality rates in '''endemic areas may be in the region of 4-5% whereas rates from 20% to 90% in epidemic outbreaks''' have frequently been reported<ref name="Rossiter">Rossiter, P. B., Taylor, W.P (1993) '''Peste des Petits Ruminants'''. In: ''Infectious Diseases of Livestock'', with special reference to Southern Africa. Chapter 75</ref>.  

Because colostral antibody protects young animals, in endemic areas most disease occurs in animals after waning of colostral immunity, from '''4 months to 2 years of age'''. Mortality rates in '''endemic areas may be in the region of 4-5% whereas rates from 20% to 90% in epidemic outbreaks''' have frequently been reported<ref name="Rossiter">Rossiter, P. B., Taylor, W.P (1993) '''Peste des Petits Ruminants'''. In: ''Infectious Diseases of Livestock'', with special reference to Southern Africa. Chapter 75</ref>.  

Seasonality in breeding, in marketing and in crop production all appear related to disease occurrence. In arid and semi-arid zones, infection may spread when animals are sold in the dry season. In humid zones, tethering and sale of surplus animals may occur at the start of the rains, thus aiding transmission.. The wet season can also predispose to secondary bacterial infections, exacerbating the viral pneumonia.

Seasonality in breeding, in marketing and in crop production all appear related to disease occurrence. In arid and semi-arid zones, infection may spread when animals are sold in the dry season. In humid zones, tethering and sale of surplus animals may occur at the start of the rains, thus aiding transmission. The wet season can also predispose to secondary bacterial infections, exacerbating the viral pneumonia.

== Distribution ==

== Distribution ==

From South Asia through the Middle East, and from the horn of Africa through to West Africa.  

From South Asia through the Middle East, and from the horn of Africa through to West Africa.  

PPRV has a '''direct life cycle''', maintained by infected animal to susceptible animal transmission, without involvement of carrier animals or vectors. The only requirement is a regular supply of susceptible hosts plus sufficient animal movement to allow mixing of the population<ref name="Rossiter" />

PPRV has a '''direct life cycle''', maintained by infected animal to susceptible animal transmission, without involvement of carrier animals or vectors. The only requirement is a regular supply of susceptible hosts plus sufficient animal movement to allow mixing of the population<ref name="Rossiter" />.

== Clinical Signs ==

== Clinical Signs ==

== Pathology ==

== Pathology ==

The carcass is usually '''dehydrated, and soiled with faeces'''. The peri-orbital and perinasal areas are usually encrusted with muco-purulent discharges. The '''erosions and ulcerations''' in the mouth and throat are usually prominent, as is the presence of the secondary broncho-pneumonia. The underlying primary viral pneumonia may be less obvious but is manifested by areas of red consolidation.<ref> Rowland, A. C., Scott, G. R., Hill, H. D (1969) '''The pathology of an erosive stomatitis and enteritis in West African Dwarf goats.''' J Pathology, 98:83-87</ref>

The carcass is usually '''dehydrated, and soiled with faeces'''. The peri-orbital and perinasal areas are usually encrusted with muco-purulent discharges. The '''erosions and ulcerations''' in the mouth and throat are usually prominent, as is the presence of the secondary broncho-pneumonia. The underlying primary viral pneumonia may be less obvious but is manifested by areas of red consolidation.<ref> Rowland, A. C., Scott, G. R., Hill, H. D (1969) '''The pathology of an erosive stomatitis and enteritis in West African Dwarf goats.''' ''J Pathology'', 98:83-87</ref>

'''Zebra striping in the colon''' may also be seen, and lymphadenopathy.

'''Zebra striping in the colon''' may also be seen, and lymphadenopathy.

From the necropsy examination of two to three animals, lymph nodes, especially the mesenteric and bronchial nodes, lungs, spleen and intestinal mucosae should also be collected aseptically, chilled on ice and transported under refrigeration. Fragments of organs collected for histopathology are placed in 10% formalin.  

From the necropsy examination of two to three animals, lymph nodes, especially the mesenteric and bronchial nodes, lungs, spleen and intestinal mucosae should also be collected aseptically, chilled on ice and transported under refrigeration. Fragments of organs collected for histopathology are placed in 10% formalin.  

Detection of virus antigens by the '''agar gel immunodiffusion test (AGIDT)''' is a relatively simple, fast and cheap process. It is extremely useful as an initial test, but it does not discriminate between PPR and rinderpest viruses and further tests are needed to do this.  

Detection of virus antigens by the [[Immunodiffusion|'''agar gel immunodiffusion test (AGIDT)''']] is a relatively simple, fast and cheap process. It is extremely useful as an initial test, but it does not discriminate between PPR and rinderpest viruses and further tests are needed to do this.  

Histopathology combined with '''immunohistochemical staining (e.g. immunoperoxidase)''' is a useful procedure because it is performed on formalin-fixed material and can discriminate between PPR and rinderpest when performed with specific monoclonal antibodies. Virus antigens can also be detected by '''immunocapture ELISA'''.  

Histopathology combined with '''immunohistochemical staining (e.g. immunoperoxidase)''' is a useful procedure because it is performed on formalin-fixed material and can discriminate between PPR and rinderpest when performed with specific monoclonal antibodies. Virus antigens can also be detected by '''immunocapture [[ELISA testing|ELISA]]'''.  

Antigen-capture [[ELISA testing|ELISA]] is sensitive and specific, using monoclonal antibodies to give a result with PPR virus and enabling differentiation from Rinderpest but taking longer than CIEP.

Antigen-capture [[ELISA testing|ELISA]] is sensitive and specific, using monoclonal antibodies to give a result with PPR virus and enabling differentiation from rinderpest but taking longer than counter-immuno-electrophoresis (CIEP).

'''Antibodies''' are strongly induced by infection, and become detectable from the '''diarrhoeic stage onwards'''.  

'''Antibodies''' are strongly induced by infection, and become detectable from the '''diarrhoeic stage onwards'''.  

The prescribed test for international trade (that which is accepted as a basis for the veterinary certification of animals as having evidence of presence or absence of antibodies) is '''Virus Neutralisation'''.<ref> OIE (2000) The Manual of Standards for Diagnostic Tests and Vaccines. Paris, France: Office International Des Epizooties</ref> There is however cross-neutralisation between antibodies to PPR and RPV. The OIE considers that a serum is considered to be positive for PPR when the neutralisation titre is at least '''two-fold higher for PPR than for rinderpest'''.

 

The prescribed test for international trade (that which is accepted as a basis for the veterinary certification of animals as having evidence of presence or absence of antibodies) is '''Virus Neutralisation'''.<ref> OIE (2000) '''The Manual of Standards for Diagnostic Tests and Vaccines. '''Paris, France: ''Office International Des Epizooties''</ref> There is however cross-neutralisation between antibodies to PPR and RPV. The OIE considers that a serum is said to be positive for PPR when the neutralisation titre is at least '''two-fold higher for PPR than for rinderpest'''.

== Treatment ==

== Treatment ==

Gargadennec, L., Lalanne, A (1942) '''La peste-des-petits-ruminants'''. ''Bulletin du Service Zootechnique Epizootique du Afrique Occidentale Francaise'', 5:16-21.

Gargadennec, L., Lalanne, A (1942) '''La peste-des-petits-ruminants'''. ''Bulletin du Service Zootechnique Epizootique du Afrique Occidentale Francaise'', 5:16-21.

Libeau, G., Diallo, A., Colas, F., Guerre, L (1994) '''Rapid differential diagnosis of rinderpest and peste des petits ruminants using an immunocapture ELISA'''. Vet Record, 134(12):300-304; 24.

Libeau, G., Diallo, A., Colas, F., Guerre, L (1994) '''Rapid differential diagnosis of rinderpest and peste des petits ruminants using an immunocapture ELISA'''. ''Vet Record'', 134(12):300-304; 24.

OIE (2001) '''World Animal Health in 2000. Parts 1 and 2'''. Paris, France: ''Office International Des Epizooties''.

OIE (2001) '''World Animal Health in 2000. Parts 1 and 2'''. Paris, France: ''Office International Des Epizooties''.

Raj, G. D., Nachimuthu, K., Nainar, A. M (2000) '''A simplified objective method for quantification of peste des petits ruminants virus or neutralizing antibody'''. J Virological Methods, 89(1/2):89-95.

Raj, G. D., Nachimuthu, K., Nainar, A. M (2000) '''A simplified objective method for quantification of peste des petits ruminants virus or neutralizing antibody'''. ''J Virological Methods'', 89(1/2):89-95.

 

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[[Category:Sheep Viruses]][[Category:Goat Viruses]][[Category:Intestinal Diseases - Sheep]][[Category:Alimentary Diseases - Goat]][[Category:Respiratory Diseases - Sheep]][[Category:Respiratory Diseases - Goat]]

[[Category:Sheep Viruses]][[Category:Goat Viruses]][[Category:Intestinal Diseases - Sheep]][[Category:Alimentary Diseases - Goat]][[Category:Respiratory Diseases - Sheep]][[Category:Respiratory Diseases - Goat]]

[[Category:Morbilliviruses]] [[Category:To Do - CABI review]]

[[Category:Morbilliviruses]] [[Category:To Do - Steph]]