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Field Diagnosis and Sampling Techniques
For
The Priority of Diseases
Laboratory Diagnosis of Viral Infections
Collection , Submission and preservation of Specimens.
In clinical cases the specimen for isolation of virus should be collected at the optimal time ,i.e., during the early acute stage of the disease and prior to the presence and influence of antibody on the course of the disease
Con…
Most laboratories supply a specimen submission form that should be completed with the available information. In the absence of a form, the veterinarian should supply as complete a history as possible.
Con…
Animals
Live, sick animals are preferable to dead animals.
If a herd problem exists, more than one animal should be submitted.. Do not freeze animals submitted for necropsy.
FOOT AND MOUTH DIESASE
ELU
Background
highly contagious and sometimes fatal viral disease of cloven-hoofed animals, including:
domestic animals such as cattle, water and African buffalo, sheep, goats and pigs,
In addition elephants.
ELU
Background
Cattle and African buffalo are the usual maintenance hosts for FMDV in Africa.
Consequences may include decreased milk yield, permanent hoof damage and chronic mastitis.
High mortality rates can be seen in young animals.
Immunity to one serotype does not provide any cross-protection to other serotypes.
Sheep may have less obvious symptoms than other species.
Causative Agent
Picornaviruses are among the most diverse (more than 200 serotypes) and 'oldest' known viruses. FMDV was one of the first viruses to be recognized
Name: 'Pico (Greek = very small) RNA Viruses'.
Causative Agent
Causative Agent
FMDV serotypes and strains vary within each geographic region.
Serotype O is the most common serotype worldwide. This serotype is responsible for a pan-Asian epidemic that began in 1990 and has affected many countries throughout the world.
Other serotypes also cause serious outbreaks.
Immunity to one serotype does not provide any cross-protection to other serotypes.
Cross-protection against other strains varies with their antigenic similarity.
ELU
Survival
There is limited information on the survival of FMDV in the environment, but most studies suggest that it remains viable, on average, for three months or less.
In very cold climates, survival up to six months may be possible. Virus stability increases at lower temperatures;
Survival
FMDV is inactivated at pH below 6.5 or above 11.
This virus can persist in meat and other animal products when the pH remains above 6.0, but it is inactivated by acidification of muscles during rigor mortis.
It can survive for long periods in or frozen lymph nodes or bone marrow.
ELU
Incubation Period
In cattle, the incubation period varies from two to 14 days, depending on the dose of the virus and route of infection.
In pigs, the incubation period is usually two days or more, but can be as short as 18-24 hours.
The incubation period in sheep is usually 3 to 8 days. Incubation periods as short as 24 hours and as long as 12 days have been reported in this species after experimental infection.
ELU
Clinical sign
http://www.cfsph.iastate.edu/DiseaseInfo/clinical-signs-photos.php?name=foot-and-mouth-disease
ELU
Rift Valley Fever
Causative agent:
Bunyaviridae (RNA) Phlebovirus
Species:
Sheep, cattle and camels
Symptoms:
Fever, abortion , anorexia, depression, weakness, diarrhea and incoordination collapse and death
Samples:
Blood in anticoagulant from febrile cases, serum , spleen, brain and liver in10formol saline
VI-histopathology and AGID
Lumpy Skin Disease
Causative agent:
Poxviridae (DNA) Capripoxvirus
Species:
Cattle
Symptoms:
Fever -depression –emaciation ,conjunctivitis -intra dermal cutanaeous nodules -lymphadenitis
Samples:
Biopsy from cutanaeous nodules and
alfthe specimen in 10formolsaline)
Lab Tests:
ELISA –(Ag orAb)detection
PCR
FAT
examined for presence of intracytoplasmic inclusion bodies
Laboratory Diagnosis of Peste Des Petites Ruminants
PPR
ELU
History
PPRV is transmitted mainly by aerosols between animals living in close contact.
ELU
BACKGROUND
PPR is an acute viral disease of small ruminants characterized by:
(fever, oculonasal discharges, diarrhoea and pneumonia with foul offensive breath)
Infected animals present clinical signs similar to those of rinderpest in cattle, from which it must be differentiated.
Because of the respiratory signs, PPR can be confused with contagious caprine pleuropneumonia (CCPP) or pasteurellosis.
ELU
BACKGROUND
The disease affects mainly goats and sheep, but it is usually more severe in goats where it causes heavy losses and is only occasionally severe in sheep.
Generally cattle can only be infected subclinically. However, in poor conditions it might be possible that cattle develop lesions following PPRV infection, calves experimentally infected with PPRV.
Cases of clinical disease have been reported in wildlife.
ELU
PPR Virus
Pest des petit ruminant virus (PPRV) is a member of the genus morbillivirus in the family Paramyxoviridae.
morbillivirus comprises: Measles virus (MV) of humans, rinderpest virus (RPV), canine distemper virus (CDV) of dogs and some wild carnivores, dolphin distemper viruses that infect marine mammals.
ELU
Laboratory diagnosis of PPR
Lab diagnosis of PPR is based on viral isolation, detection of viral antigens and/or viral nucleic acid, and serological tests.
Agar Gel Immunodiffusion (AGID) test
Haemoagglutination test (HA)
Immunocapture ELISA (Ic-ELISA)- Antigen detection
Sandwich ELISA (S-ELISA).
Samples to be collected
Blood in anticoagulant (EDTA)from febrile cases
lymph nod ,spleen and Lung (ice and 10formolsaline
Laboratory diagnosis of PPR -Antibodies detection
Competitive ELISA(c-ELISA):
Other tests i.e. AGID, HA, CIEP etc can also be used for antibodies detection.
Laboratory Diagnosis of Sheep & Goat Po
ELU
Sheep and Goat Pox
Family Poxviridae
Genus Capripoxvirus
Only one serotype
Prolonged survival in the environment
Survives in scabs for 3 months
Clinical Signs
Incubation period: 4 - 13 days
Fever
Conjunctivitis
Depression, anorexia
Dyspnea, nasal or ocular discharge
Secondary bacterial
infections are common
Clinical Signs
Papules forming into hard scabs.
Lesions may cover body or be restricted.
Death may occur at any stage.
Post Mortem Lesions
Skin infected and papules
Nodules in lungs
Swollen lymph nodes
Sampling
Before collecting or sending any samples, the proper authorities should be contact.
Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease
Differential Diagnosis
Bluetongue
Mycotic dermatitis
Sheep scab
Mange
Photsensitization
Peste des petits ruminants
Parasitic pneumonia
Caseous lymphadenitis
Insect bites
Diagnosis
Clinical:
Suspect in animals with characteristic full-thickness skin lesions, fever and lymphadenitis
Laboratory Tests:
Virus isolation, electron microscopy, virus neutralization, AGID, indirect fluorescent antibody test, PCR
Characteristic histopathological lesions
Diagnosis-Antigen detection
Viral antigens can be detected in tissues by:
agar gel immunodiffusion (AGID) (ELISAs).
Counter-immunoelectrophoresis
latex agglutination and;
indirect agglutination tests.
Diagnosis-Antibodies detection
Antibodies to capripoxviruses can be found approximately one week after the skin lesions appear.
Sero-logical tests include virus neutralization, AGID, the indirect fluorescent antibody test (IFA), ELISAs and immunoblotting (Western blotting).
Brucellosis is considered as the most wide spread zoonosis in the world and it is considered as True zoonosis ( That mean it is Basically transmitted from animal to human).
The importance of this contagious disease is the economic impact on livestock industry.
Causes sever hazard to human health, through either direct contact with infected animals or the consumption of contaminated milk and dairy products.
Causative bacteria of the disease
For serological examinations:
Serum samples are collected for serological diagnosis.
Collect 5-10 ml of blood in plain tubes (with out EDTA).
Avoid shaking of the tubes (which contain blood) at transporting to prevent distraction of the RBCs and hemolysis.
Try to separate the serum from clotted blood as possible as you can.
The tubes are placed vertically at room temperature for 1 hour then refrigerated at (4 - 8 °C) for 1- 2 hour. Don’t refrigerate the whole blood immediately after collection.
Don’t freeze the whole blood.
After the serum was separated distribute it equally in to two plastic tubes for serum and keep it in a refrigerator for short periods or in freeze for longer periods.
Avoid repeated freezing & thawing as this may affect the protein structure of the serum.
The most valuable samples from live animals are semen, vaginal swabs, and milk.
After necropsy, the preferred organs are epididymas, seminal vesicles & inguinal lymph nodes in rams, and the uterus, iliac and supra mammary lymph nodes in ewes.
In aborted and stillborn lambs the preferred culture sites are abomasal content and lung.
Samples for culture should be transported to the laboratory on ice as soon as possible after collection.
Samples for diagnosis
Collect vaginal discharge into a sterile universal bottle for bacteriology.
Submit whole fetus to laboratory for necropsy..
select portions of fetal lung and liver and place in separate sterile universal bottles. Make films from fetal stomach contents, vaginal discharge, fetal lung and liver. Fix these smears in methanol and send to the laboratory.
Rose Bengal Test (RBT).
Complement Fixation Test (CFT).
Enzyme Linked Immuno Sorbent Assay (ELISA).
Milk Ring Test (MRT).
Standard Agglutination Test (SAT).
Contagious Bovine Pleuro-Pneumonia
This is a contagious pneumonic disease of cattle caused by Mycoplasma mycoides var mycoides. Affected animals suffer persistent coughing, difficulty breathing, and discharging from the nose and mouth. The disease causes pneumonia, serofibrinous pleurisy fluid in the chest cavities and interlobular edema of the lungs. Acutely affected cattle show fever, rapid respiration rate, anorexia and depression. A cough develops, breathing becomes difficult and nasal and oral discharges are seen
Samples for diagnosis
Send portions of affected lung and pleural exudates, collected aseptically from the chest cavity, either fresh or preserved in 50% glycerol saline.
Blocks of lung tissue, preserved in 10% formol saline .
Infection can be confirmed serologically by
means of the complement fixation test or ELIS
د/ منتصر محمد عبدالله
السودان / نهر النيل /شندي
ساحة النقاش