Healthy Productive Animals

Animals are kept for various purposes. In order to be useful, the animals must be healthy, but constraints to animal health vary with the production systems in which they are kept. A majority of the constraints are in the category of feeds and health. Feed quality and utilization can be improved in ways that do not involve the use of diagnostics. The threat of disease must be minimized or removed in order for animals and their keepers to remain healthy. Effective detection of pathogens and diagnosis of diseases require appropriate and reliable diagnostics. An important function of diagnostics in connection with animal disease is to contribute to improved welfare and productivity of the animals through the control of diseases.[3]

A majority of animal diseases that occur in the developed world have been controlled through a combination of effective diagnosis, treatment, and vaccination. However, in the developing world, many diseases pose a serious threat to the welfare of animals and their keepers. A partial list of economically important animal diseases is given in Table 1.[4] Diagnostic tests that have been developed for some of the listed diseases are not efficiently linked with other indicator systems to provide meaningful decision support tools for therapy, strategy development, and trade in animal products.

To be appropriate for the tasks in animal health care, diagnostic test components should be of known identity; pure in quality, produced in vitro synthetically or through recombinant DNA; precise and specific in identifying disease; linked to important traits or phenotypes; and able

Table 1 Selected pathogens thai

: cause diseases in animals and humans, their distribution, and the assays commonly used to detect exposure

Pathogen

Disease name

Species affected

Distribution

Test system

Diagnostic performance

Bacteria

Bacillus anthracis

Anthrax

All livestock species,

Worldwide

Serological (Ab-ELISA) PCR

Requires improvement

humans

Clostridium chauvaei

Black-leg

Cattle, sheep

Worldwide

Serological (IFA)

Requires improvement

Clostridium botulinum

Botulism

All livestock species,

Worldwide

Neutralization of toxins

Requires improvement

humans

Brucella abortus

Brucellosis

All livestock species

Worldwide

Rose bengal plate

Good

agglutination PCR,

DNA probes, CFT ELIS A

B. melitensis

Brucellosis

All livestock species

Worldwide

Rose bengal plate

Good

agglutination PCR,

DNA probes, CFT ELIS A

Chlamydia trachomatis

Chlamydial infections

All livestock species,

Worldwide

Cell culture, PCR, Ab-ELISA

Good

humans

Chlamydia suis

Chlamydial infections

Porcine, humans

Worldwide

Cell culture, PCR, Ag-EILSA

Good

Mycoplasma mycoides

Contagious bovine

Cattle

Africa, Asia

CFT, C-ELISA

Good in combination

mycoides

pleuropneumonia

(CBPP)

Mycoplasma mycoides capri

Contagious caprine

Sheep, goats

Africa, Middle East

CFT, latex agglutination

Good in combination

pleuropneumonia

(CCPP)

Dermatophilus congolensis

Dermatophilosis

Cattle, sheep, goats

Africa

Giemsa, IFA

Insensitive

Pasteurella multocida

Fowl cholera

Poultry

Worldwide

Culture, PCR

Good

Salmonella pullorum,

Fowl typhoid

Poultry

Worldwide

Culture, serum agglutination

Good

S. gallinarum

test, PCR

Leptospira spp

Leptospirosis

All livestock species

Worldwide

Microscopic agglutination test,

Need improved assay

(not poultry), humans

Ab-ELISA

for chronic cases

Listeria monocytogenes

Listerosis

All livestock species,

Worldwide

Culture, PCR

Good

humans

Brucella metitensis

Malta fever

Sheep, goats, humans

Worldwide

C-ELISA, CFT, PCR, FPA

Good

Mycobacterium

Paratuberculosis,

Cattle

Worldwide

Culture, AGID

Good

paratuberculosis

(Johne's disease)

Ab-ELISA, PCR

(Para-TB)

Mycobacterium bovis

Tuberculosis (TB)

Cattle, humans

Africa

Culture, Tuberculin test PCR

Good

Parasites

Babesia bigemina

Babesiosis

Cattle

Worldwide

Ab-ELISA, PCR

Good

B. bovis

Babesiosis

Cattle

Worldwide

C-ELISA, PCR

Good

Coccidia spp.

Coccidiosis

All livestock species

Worldwide

Parasitological

Inadequate

Taenia saginata

Cysticercosis

Humans, cattle

Worldwide

Ag-ELISA for both humans

Lacks required specificity

(Cysticercus bovis)

(beef tapeworm)

and animals

Gastro-intestinal (Gl) parasitism (helminthosis) (e.g., Haemonchus, Ostertagia, Onchocerca, Ascaris, Trichostrongylus, Bunostomum, Cooperia, Strongyloides, Nematodirus, Toxocara, Trichuris, etc.) Haemonchus contortus

Echinococcus granulosus,

E. multilocularis, and other Echinococcus spp. Fasciola hepatica,

F. gigantica Dirofilaria immitis Various species of ticks Trypanosoma evansi

Trypanosoma congolense, T. brucei si. T. vivax, T. brucei

Theileria annulata

East Coast Fever (ECF)

Various helminth species

Cattle

All livestock species

Haemonchosis

Hydatidosis (hydatid disease)

Fascioliasis (liver fluke)

Filariasis Tick infestation Surra

Trypanosomosis

Tropical theileriosis

Cattle, sheep, goats

All livestock species, humans

Buffalo, cattle, sheep, goats All livestock species All livestock species Buffalo, cattle, camels, horses, donkeys, mules Cattle, sheep, humans

Cattle

Rickettsia

Anaplasma marginale Cowdria ruminantium

Viruses

Iridovirus Rhinovirus (various serotypes) Pox virus IBD virus

Pox virus

Anaplasmosis Heartwater

African swine fever Foot-and-mouth disease (FMD) Fowl pox Gumboro disease (infectious bursal disease, IBD) Lumpy skin disease

Cattle, sheep, goats Cattle, sheep, goats

Pigs

Cattle, sheep, goats, pigs Poultry Poultry

Cattle

East, Central, Ab-ELISA, PCR Good

Southern Africa

Worldwide Parasitological Molecular/immunological assays needed

Worldwide Worldwide

Worldwide

Worldwide Worldwide Africa, Asia, South America Africa,

South America

Parasitological Necropsy/organ examination

Parasitological, Ab-ELISA

PCR, Ab-ELISA Toxonomy CATT, PCR

Parasitological IFA

Molecular/immunological assays needed Molecular/immunological assays needed

Good

Good Good Good

Needs improvement

North Africa, Middle East, Asia, China, continental Europe

Worldwide Africa, Caribbean

Africa Worldwide

Worldwide Worldwide

Ab-ELISA, IFA

Ab-ELISA, C-ELISA, PCR Ab-ELISA, PCR

Ab-ELISA, PCR IFA VN, Ab-ELISA, CR

VN, IFA Ab-ELISA AGID, VN, Ab-ELISA

Good

Good

Fair, needs improvement

Good Good

Good Good

Africa

Virus neutralization

Insensitive

{Continued)

Table 1 Selected pathogens that cause diseases in animals and humans, their distribution, and the assays commonly used to detect exposure (Continued)

Pathogen

Disease name

Species affected

Distribution

Test system

Diagnostic performance

Pox virus

Sheep and goat pox

Sheep, goats

Africa, Middle East, China

VN, AGID, IFA

Insensitive

Ganjam group virus

Nairobi sheep disease

Sheep, goats

East Africa

IFA, CFT

Insensitive but satisfactory

Paramyxovirus

Newcastle disease (ND)

Poultry

Worldwide

Hemoagglutination-inhibition

Good

Morbillivirus

Peste des petits ruminants (PPR)

Sheep, goats

Africa, Middle East

VN, C-ELISA

Good

Morbillivirus

Rinderpest (RP)

Cattle, buffalo, pigs sheep, goats

Africa, southern Asia

C-ELISA, VN

Good

Lyssavirus

Rabies

All livestock species (not poultry), humans

Worldwide

VN, IFA, RREID

Good

Bunyavirus

Rift Valley fever (RVF)

Sheep, cattle, goats, humans

Africa

VN, ELISA

Good

Rhabdoviridae

Vesicular stomatitis

Horses, cattle, pigs

Sheep, goats, humans

Americas

Liquid-phase blocking ELISA, VN

Good

Orbivirus

Blue tongue

Sheep

Africa

C-ELISA

Good

Orbivirus

African horse sickness

Horses

Africa, Middle East

VN, ELISA, CFT

Good

Abbreviations'. CFT: complement fixation test; C-ELISA: competitive-enzyme linked immunosorbent assay; Ag-ELISA: antigen-ELISA; Ab-ELISA: antibody-ELISA; VN: virus neutralization; PCR: polymerase chain reaction; IFA: immuno-fluorescent assay; RREID: rapid enzyme immunodiagnosis; AGID: agar gel immunodiffusion; FPA: fluorescence polarization assay

Abbreviations'. CFT: complement fixation test; C-ELISA: competitive-enzyme linked immunosorbent assay; Ag-ELISA: antigen-ELISA; Ab-ELISA: antibody-ELISA; VN: virus neutralization; PCR: polymerase chain reaction; IFA: immuno-fluorescent assay; RREID: rapid enzyme immunodiagnosis; AGID: agar gel immunodiffusion; FPA: fluorescence polarization assay to provide an index of host morbidity. Diseases for which diagnostics are required include infectious diseases, diseases with impact on general socioeconomic development, zoonotic diseases, genetic diseases, and diseases of intensification. A diagnostic test needs to have been validated. The validation process quantifies the performance of the test, the possible errors, and the likelihood of their occurrence. Additionally, it gives criteria of reliability, reproducibility, and relevance.

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