Animals must have a strong and efficient immune system in order to resist infectious diseases. Vaccination is considered to be an effective solution for disease prevention however, success is often limited. If vaccines are not available, disease prevention strategies are practiced which costs high, often time consuming and involves environment cleanliness, antibiotic therapy for treating clinical diseases and even culling of affected animals. To bypass this situation, use of immunomodulatory (immunoenhancing) compounds would be an effective way to nonspecifically increase the immunocompetence of animal. Immunomodulation aimed at increasing the effectiveness of immune cell in general, rather being specific to a particular pathogen.
Chromium (Cr) is a micronutrient in the transition series of trace elements. The nutrient form of Cr is trivalent Cr (Cr3+). To become bioactive, it becomes part of GTF- Glucose tolerance factor structure, which was first isolated from yeast. GTF structure contain nicotinic acid molecules, amino acids of glutathione peptide.
GTF-Cr3+ is co-factor for insulin activity. It is needed to facilitate insulin to move glucose from blood into cells. Therefore, it has role in amino acid, carbohydrate and lipid metabolism. Along with it, also enhance immunocompetence and disease resistance during stress conditions by reducing blood cortisol therefore, important for health maintenance. It has well documented that stress and glucocorticoid (cortisol) have immunosuppressive effects on cells of immune system.
During stress condition, glucose metabolism increases simultaneously with increased secretion of stress-induced glucocorticoid (cortisol) which work antagonistically to insulin and prevent entry of glucose into periphery tissue (e.g. muscle and fat) to spare it for tissue of high demand (e.g. brain and liver). This result in elevation of blood glucose and subsequent mobilization of Cr from body stores; once mobilized, Cr is irreversibly lost in urine. If dietary supplies are inadequate, reserves can be depleted.
Cr deficiency is not common in normal farm conditions. Animals subjected to stress are often Cr. deficient. Supplemental Cr have immunoenhancing capabilities for stressed animals however, timing of supplementation in relation to stress and infection is important. Incidence of infectious diseases can be reduced and production potential can be increased if diets are supplemented with organic Chromium prior or during period of normal production stress.
Cr Supplementation:
- Elevated immunoglobulin level
- Decrease serum cortisol level
- Reduce morbidity and rectal temperature
- Less respiratory disease, reduce ketosis
- Increase resistance to pneumonia
LUMPY SKIN DISEASE (LSD) SNAPSHOT
In Brief
Lumpy skin disease (LSD) is an enzootic highly infectious viral disease. It can be of acute to chronic nature. Poxvirus belonging to sheep pox and goat pox family are responsible of causing lumpy skin disease in cattle.
Economic Impact
Permanent damage to hides, value depreciation
Production and reproduction losses
Loss of valuable genetics
Costly control and eradication measures
Disrupted trade
Aetiology
Family – Poxviradae
Genus – Capripoxvirus
Species- Sheep pox virus, goat pox virus, lumpy skin disease virus (morphologically indistinguishable from each other and adapted to different host species)
Prototype strain of LSD – Neethling virus.
Host – Cattle and Domestic Asian Buffalo
(Imported breeds with thinner skin are more susceptible than indigenous breeds with thicker skin)
Susceptible stages- All ages but high risk in lactating Cows, Young heifer, malnourished cows due to impaired humoral immunity
Transmission
- Arthropods vector (blood-feeding mosquito, flies and ticks) spread mechanically rather than biologically.
- Direct contact with contaminated feed and water
- Virus is present in nasal, lachrymal and pharyngeal secretion, semen, blood and milk of infected animal that could play some part in transmission but virtually all viral outbreaks propagated by a continuous cattle-arthropod-cattle cycle.
Occurrence – wet and warm weather, following seasonal rain as it favor arthropods replication
Incubation period
In Natural outbreak 1-4 weeks (OIE terrestrial Animal Health Code gives a max. incubation period of 28 days)
Persistence of virus
Environment– up to 6 mo. in suitable conditions
Live animals-
Viraemia lasts for 4-5days | Saliva– 11 days | Semen – 22 days | Skin (necrotic tissue) – 33 days | Meat – no evidence | Milk – in early stages of infection
Hides – for months Fomites – for 6 months Vectors – not more than 4 days in insects
Reported Outbreak Countries
Origin early-mid 19’s: Zambia, Africa, Israel, Middle East, Iran, Northern Part of Cyprus, Europe and Greece
2014- Turkish Border, Northern Caucasus region including Azerbaijan, Georgia and Russia
2016- Europe, Asia, Serbia, Albania and Kazakhstan
2019– India China Bangladesh
2021-22- Pakistan
Diagnostics
Electron microscopy examination (TEM)
Serum/virus neutralization test | PCR | ELISA
Signs and Symptoms
- Biphasic Fever 40-41.5⁰C may last for 6-72 hrs. or up to 10 days
- Watering eyes, increased nasal and pharyngeal secretions.
- Loss of appetite, drop in milk production
- Depression and lameness.
- Cutaneous eruption of nodules occur within 1-2 days.
- Main sites of nodule includes head, neck, perineum, genitalia, udder and limbs.
- Nodules – 5-50mm or more in diameter.
- Lesion develop on muzzle, pharynx, nostril, mouth, larynx, throughout alimentary canal (abomasum) become ulcerated and necrotic.
- Mucopurulent (mucus and pus) nasal discharges, persistent dribbling of saliva, coughing, snoring and often distressed respiration result.
- Inflammation of conjunctiva and cornea of eyes is common.
- Inflammatory and oedematous swellings of limbs, brisket and genitilia may develop.
- Sitfast greatly reduces mobility
- Rapid deterioration of body condition
- Pneumonia, abortion, mastitis, ochritis are common complications
- Fetuses born to infected cow may show skin lesion at birth.
Treatment
As LSD is a viral disease, has no known cure. However, to treat secondary bacterial infections, deal fever, inflammation and improve animal appetite, antibiotics and anti-inflammatory drugs or shot of vitamin are used.
Vaccination
Homologous live attenuated virus vaccine (Neethling strain: immunity conferred lasts for up to 3 yrs.)
Heterologous live attenuated vaccine (Sheep or goat pox virus may cause local or sometime severe reactions; not advised for countries free from sheep goat pox virus).
Inactivated oily adjuvanated vaccine based on Neethling strain also tested and reported to induce high level of antibodies for 1 year without any adverse effects.
No new generation recombinant capripox vaccine available for commercial purpose.
Prevention and Control
- Effective Vector Control and Vaccination programs should be in place.
- Improved chromium status for health maintenance prior to or during normal production stress
- Rapid diagnosis, Quarantine, depopulation of infected and exposed animal, proper disposal of carcasses, biosecurity measures can aid in eradication of LSD outbreaks.
