Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Animal Health Management Review of issues that influence Animal Health Management Author: Dr Mary-Louise Penrith. Licensed under a Creative Commons Attribution license. DISEASES OF IMPORTANCE TO LIVESTOCK PRODUCTION AND TRADE Infectious animal diseases can affect livestock trade in two important ways. Firstly, there are the so-called transboundary animal diseases (TADs) (see also modules on high impact diseases and on marketing and trade) that have the capacity for rapid spread over long distances and are feared by countries that have never had them or have eradicated them. For this reason they are highly trade-sensitive and countries that are free of them require assurances that they will not import them when they import livestock or livestock commodities. The World Trade Organization has mandated the OIE to develop standards for trade in live animals and livestock commodities that will prevent the spread of TADs. These standards constitute the Terrestrial Animal Health Code which is updated annually and is available on the OIE website (www.oie.int). Secondly, there are diseases, including TADs, which affect animal production and consequently reduce the amount and quality of animals available for trade. At the subsistence level of livestock production, where trade may not be an important issue, these diseases can jeopardise household food security. In poor mixed farming systems livestock are needed for crop production and if they are not there to provide manure and traction families may not have enough to eat. The important characteristics of the selected diseases are summarised in Table 3. For more details about the diseases please refer to the relevant chapters in Coetzer, J.A.W. & Tustin. R.C. 2004. Infectious Diseases of Livestock (2nd edn), Oxford University Press, Cape Town. References for Newcastle disease and avian influenza are provided at the end of the section and more information is available from the module on poultry health and production. 1|Page Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Table 3 Characteristics of diseases important for production and trade Disease FMD Viral disease that affects cloven- Geographical distribution Transmission and reservoirs Worldwide (Not N Highly contagious; Sensitive to low pH; High, mainly via live America, Australia, direct contact with cannot survive in New Zealand and most of Europe) infected animals matured muscle but animals and bone-in meat and material; survives for long airborne in special conditions periods in lymphoid Trade: Trade bans tissues, bone during outbreaks and marrow, and in some dairy products permanent market hoofed animals and camelids African buffalo (Syncerus caffer) Survival outside host Potential for transboundary spread Zoonotic potential None Effects on production and trade Production: Most severe in high-producing dairy cattle and in pigs exclusion for producers in endemic areas are the reservoir host PPR Viral disease of sheep and goats North, West and Direct contact with Ability to survive Spread is by live Central Africa as far infected animals infected animals south as Tanzania; south-western Asia and material; outside the host is poor airborne over short distances None Production: Can cause high mortality and also production losses and the potential for spread is high Trade: Uninfected countries might ban live goats from infected countries RVF Serious viral 2|Page Africa (including Transmission to Sensitive to Spread is probably RVF virus causes Major losses can occur Madagascar) and animals is by a temperature and mainly by live mild to due to abortions and the Near East number of species pH; long-term infected animals; occasionally Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease disease of domestic ruminants Geographical distribution (Saudi Arabia and Yemen) Transmission and reservoirs of mosquitoes (Aedes, Culex) Survival outside host survival is probably in mosquitoes Potential for transboundary spread Zoonotic potential Fatal viral neurological death of young animals mosquitoes may serious and even move over fatal disease in distances in vehicles humans; infection Trade in live animals is usually due to may be banned during outbreaks contact with blood of infected animals Rabies Effects on production and trade Worldwide. Many Usually by bites of Survival outside an Spread would be Rabies is a fatal disease in humans Usually only individual countries that are infected animals; animal is very brief mainly by infected free of rabies are islands other routes described are rare under natural conditions animals incubating the disease Most cases Infection is by oral Prions are highly Owing to the In the 1990s BSE Herds with an infected occurred in UK ingestion of infected tissues stable in tissues lengthy incubation was linked to a cow were culled; most and very high period (years) variant of were valuable dairy cattle animals are affected but outbreaks in cattle and wildlife have caused serious losses disease of all mammals including humans BSE BSE emerged in UK followed by other in the 1980s. It is a European countries, temperatures are before clinical signs Creutzfeld-Jakob fatal neurological Canada, Japan and disease (vCJD) USA ex Canada; no required to destroy them appear and long disease caused by a prion persistence in meat that appeared in After the link to human cases have been (certain types of younger people disease was discovered reported in the tissue) and bone there were massive southern meal the potential and is invariably fatal for transboundary 3|Page effects on trade due public fear and to Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution Transmission and reservoirs Survival outside host hemisphere Potential for transboundary spread Zoonotic potential spread is high Effects on production and trade surveillance requirements that are not easy to achieve BT Africa, Asia, Transmission by The virus is labile; it Spread is by Australia, USA, None High mortality can occur in sheep movement of Europe (recent blood-sucking midges (Culicoides is probably A vector-borne viral maintained during infected animals disease of domestic and wild ruminants introduction to N spp.) winter in midges; and possibly by Outbreaks, particularly ruminants can only wind-borne midges; in new areas, can cause be infected by midges establishment restrictions on requires suitable movement of live animals including game Europe now apparently extinct) midges to host the virus AHS A vector-borne viral disease of equines Endemic in sub- Transmission is by The virus is labile; Spread is by Saharan Africa; equines can only be infected by midges movement of epidemics occurred blood-sucking midges (Culicoides after introduction spp.) into Spain, Portugal, North Africa and the Dogs can be Near and Middle East infected by eating infected meat Zebras are considered to be 4|Page infected animals; None AHS can cause high mortality and loss of working time in horses the outbreak in Spain was traced to Movement restrictions zebras imported from Namibia can have negative effects on the high value racing industry Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution Transmission and reservoirs Survival outside host Potential for transboundary spread Zoonotic potential Effects on production and trade reservoirs of the virus ASF Endemic in sub- Highly contagious Long survival is Spread over long None High mortality can cause Saharan Africa and and transmission possible in a distances is mainly serious losses to pig ASF is a highly fatal in Sardinia (Italy); it among domestic suitable protein by infected pork producers, exacerbated viral disease of domestic pigs occurred in Western pigs is by direct environment like products; cross- Europe, Caribbean contact with chilled or frozen border sales of pigs at times by drastic control measures countries and Brazil infected pigs and in the incubatory (1960 – 1994) and contaminated pork and uncooked pork products in the Caucasus phase of the Trade restrictions are objects and eating disease may occur applied to pigs and pork and non-Caucasian infected meat; it can between Russia (2007 – present) also be via argasid ticks (Ornithodoros neighbouring countries originating from infected areas spp.) Common warthogs (Phacochoerus africanus) maintain the virus in a sylvatic cycle with Ornithodoros CSF 5|Page Worldwide with the CSF is transmitted Long survival is Spread over long exception of the directly by contact possible in a distances is mainly None High mortality can cause serious losses to pig Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution Transmission and reservoirs Survival outside host Potential for transboundary spread Zoonotic potential Highly fatal viral African region, with infected pigs suitable protein disease of domestic pigs where it is only and contaminated environment like endemic in objects; it can be chilled or frozen at times by drastic control measures Madagascar. South transmitted in Africa and Mauritius semen, vertically to pork and uncooked pork products Trade restrictions are have experienced foetuses, and under applied to pigs and pork epidemics. particular conditions can be airborne originating from infected areas Eradicated in North by infected pork products Effects on production and trade producers, exacerbated America and in CBPP Western Europe Eurasian wild boar with the exception of wild boars populations can Formerly worldwide, Direct contact The organism Spread is by become reservoirs of the virus it is now restricted between infected cannot survive for infected animals A respiratory to some countries in Africa and Near and Middle East and susceptible cattle long outside the host that may harbour disease of cattle caused by a mycoplasm Outbreaks in naïve populations can cause high mortality the mycoplasms in their nasal cavities Restrictions may be up to 40 days placed on buying before becoming animals from countries that are infected serologically positive 6|Page None Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Anthrax Geographical distribution Anthrax occurs worldwide Transmission and reservoirs Survival outside host Potential for transboundary spread Zoonotic potential Effects on production and trade Transmission is Spores can survive Spread is by Severity of If carcasses of animals usually by ingestion for very long movement of disease in humans that die of anthrax are A serious bacterial or inhalation of periods (centuries) material depends on the not dealt with promptly disease that causes bacilli or spores; in soil. Bacilli do not contaminated by route of infection. large outbreaks with disease in a wide variety of mammals mechanical survive long in spores, for example Percutaneous 100% mortality can transmission by carcasses and must the hides of infection results in biting flies has been reported be released into the animals; outbreaks the skin form occur in ruminants, including in wildlife environment for sporulation to occur have been traced to (sores), while hide drums ingestion of Anthrax is considered imported into infected meat one of the foremost Europe and USA from Africa results in the potential bioterrorism agents pharyngeal form that is fatal if not treated. Inhalation of spores can result in serious, often fatal systemic disease ECF and CD Theileriosis is caused by a protozoan blood parasite Theileria 7|Page Both diseases are Transmission is via endemic in some the bites of the countries in subSaharan Africa No survival outside the host or vector Spread is by None Both diseases can movement of cause high mortality and ixodid tick vector, infected cattle ECF can also reduce mainly Rhipicephalus (ECF) and buffalo performance in endemic areas (CD) or ticks; it may Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution parva; cattle are Transmission and reservoirs Survival outside host Potential for transboundary spread Zoonotic potential appendiculatus occur between There are restrictions on neighbouring countries trade in buffalo from CD- African buffalo are affected infected areas; some reservoir hosts of CD Trypanosomosis Nagana in cattle is (nagana) widespread in Tsetse flies (Glossina spp.) tropical Africa and transmit the distribution is trypanosomes that cause nagana determined by the local trade restrictions may result from ECF The parasite cannot Spread is by Human sleeping Mortality is usually low survive outside the host and vector movement of except in newly infected cattle but sickness is caused by Trypanosoma the disease can brucei gambiense affected cattle are less only be established and T. b. rhodesiense productive and often in very poor condition None European cattle breeds None presence of the vector Bovine babesiosis Heartwater 8|Page Effects on production and trade where there are tsetse flies introduced cattle, but The parasites tropical, subtropical The ticks Rhipicephalus and warm (Boophilus) temperate regions decoloratus and outside the host and vectors wherever the vectors are present R.(B.) microplus Infected cattle or ticks can introduce babesiosis to new areas as occurred in Australia with the introduction of B. microplus Throughout sub- Ehrlichia The parasite cannot Infected cattle can Saharan Africa, ruminantium is spread the agent due to high mortality in mainly in tropical transmitted by ticks survive outside the host and vector and the vector, ruminants including and subtropical of the genus which can become some wild species when Widespread in cannot survive transmit babesias are most severely affected Major stock losses occur Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution Transmission and reservoirs Survival outside host Potential for transboundary spread areas; was Amblyomma; A. established if established on two Caribbean islands variegatum is the conditions are suitable most important Zoonotic potential Effects on production and trade introduced into endemic areas vector in southern Africa Bovine anaplasmosis None Worldwide; endemic Ticks transmit the The parasite cannot Spread is by The effects range from a in most of southern anaplasmas; the movement of drop in milk production, Africa (cattle farming areas) main vector is Rhipicephalus survive outside the host and vector infected cattle and weight loss and poor this can result in conditions with slow (Boophilus) outbreaks in non- recovery to high decoloratus, but endemic areas but mortality (up to 50%); three other species of Rhipicephalus establishment is temporary infertility may only possible where occur as well as and Hyalomma suitable tick vectors occur abortions and neonatal deaths marginatum rufipes can transmit the agent Newcastle disease Worldwide Direct contact with The virus is easily Spread is mainly by Mild conjunctivitis ND can cause severe movement of live poultry in humans has been described losses due to mortality infected birds or inactivated by ND is a viral contaminated changes in pH and disease of birds material resulting in disinfectants but (probably all ingestion or faeces are a potent species) that occurs inhalation of source of infection 9|Page as well as drop in egg production and growth Trade restrictions may Livestock Health, Management and Production › Animal Health Management › Review of issues that influence animal health management Disease Geographical distribution Transmission and reservoirs infected material in mild to virulent forms Survival outside host Potential for transboundary spread Zoonotic potential for other birds Effects on production and trade occur during outbreaks Ducks are relatively resistant to ND Avian influenza Worldwide Direct contact with The virus is easily Live infected poultry H5N1 HPAI has High mortality occurs infected birds or inactivated but can and infected caused more than and because of the Viral disease of contaminated persist in faeces at migratory birds 300 human deaths zoonotic potential even birds that varies matter, including water, and aerosols low temperatures have proven highly since 2002 birds infected with LPAI for up to 44 days as well as in water efficient in moving although humans the virus over long distances are relatively are killed so losses can be very heavy resistant to infection Trade restrictions are from mild (low pathogenic AI) to highly fatal (highly Some water birds pathogenic AI, HPAI) appear to be relatively resistant severe if there is an outbreak and trade is also damaged by fear of human disease 10 | P a g e