VPP 322: Aquatic Animal Diseases, Health Care and Management (1+1)

ADVANTAGES OF VACCINATION

• The advantages of vaccination over the use of antibiotics in protecting fishes against diseases are

Vaccination	Antibiotics
Prophylactic	Curative or treatment measure (given only when disease is seen).
Disease protection effect is provided for a long duration	Disease protection is for a short duration.
All the fishes can be treated with vaccines by immersion method	Treatment is limited as antibiotics can be given only through feed. Diseased or infected fishes cease to feed. Hence delivery of antibiotics in such cases is difficult.
No side effects	Have side effects both on the host and on the disease causing organism. Higher doses would be toxic or lethal to the host and may also result in the emergence of antibiotic resistant pathogens.
No residual accumulation	Some residues are toxic and accumulates in the carcass of the fish. They may pose problem when such fishes are used for human consumption.
There is no legal restriction on the use of vaccines	Legal restrictions are present.
Theoritically vaccines can be prepared for any type pathogen and can be used for the control of diseases.	Limited to the control of bacterial diseases.
No environmantal impact is involved as vaccines are protein molecules	Have environmental impact and they kill both the pathogens and the beneficial bacteria.

• Infectious diseases such as edwardsiellosis, streptococcosis and vibriosis poses the biggest single threat to aquaculture. Researches are carried out on the development of effective vaccine, immunostimulant and adjuvant in fish. The introduction of a new generation of both oil- and non-oil adjuvant has greatly improved the efficacy of bacterial vaccines and has resulted in an impressive reduction in mortalities. Recent studies have investigated the mechanisms of induced resistance of DNA vaccines, the use of cytokines as adjuvant and the potency of novel fish antimicrobial peptides.