The value of vaccination

[ Dr Nido Tayo ]

As a practitioner in the field of animal health, the most common and pertinent question I encounter is: is vaccinating animals necessary at all?
This year’s theme of World Veterinary Day, ‘Value of vaccination’, will demystify the concerns of our pet and livestock owners.
Vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened (attenuated) or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body’s immune system to recognize the agent as foreign, destroy it, and ‘remember’ it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.
Vaccination confers active immunization, and for some disease-causing pathogens, a booster dose of vaccine is recommended as the first vaccination is often neutralized due to the presence of already-formed antibodies (passive immunization).
Annual revaccination should be followed to maintain the titer of antibodies for a particular disease.
Active immunization does not confer protection immediately to the disease against which it has been vaccinated as it takes 15-21 days to produce enough antibodies to fight a specific disease-causing organism. Therefore the window period of 15 days from the date of vaccination is very important.
Prior to any vaccination programme, it has to be ensured that the pet/livestock is dewormed, is in good health, and is not malnourished or emaciated. The animal should not have contacted the disease as most of the diseases have varied incubation periods (period of exposure to an infection to manifestation of first symptom) prior to and during the vaccination period.
Most of the enquiries regarding vaccination of pets/livestock are usually made when the disease is endemic, like
the foot-and-mouth disease in cloven-footed animals, besides rabies, canine distemper and paroviral infection in dogs.
During the endemic period, most of the animals that have come in contact with sick animals are assumed to be infected, and in such period vaccinating the animal will not give protection against that particular disease.
Veterinary vaccines have positive effects if the vaccination programmes are effectively implemented.
Veterinary vaccines are also used in livestock and poultry to maintain animal health, and to improve overall production. According to the United Nations’ economic & social affairs department’s population division, the world population is estimated to increase to just over 8 billion in 2025, and to reach 9.1 billion people in 2050.
A high-level expert forum of the UN’s Food & Agriculture Organization reported in September 2009 that in order to feed a projected world population of 9.1 billion people, the overall food production will need to increase by 70% between 2005 and 2050. Vaccines that preserve animal health and improve production are important components in meeting this need.
According to the WHO, domestic dogs are the most common reservoirs of the rabies virus, with 99% of human deaths caused by dog mediated rabies. Almost 3 billion people live in dog-mediated rabies endemic areas, putting them at risk of contracting rabies. More than 55,000 people die of rabies every year in Asia and Africa. This source of rabies in humans can be eliminated by adequate animal vaccination and control, educating those at risk, and enhancing access to appropriate medical care for those who are bitten.
Affordability and availability of rabies vaccines, along with effective vaccination programmes, are keys to changing the current situation.
Emerging and exotic animal diseases are a growing threat to human and animal health, and jeopardize food security. Increases in human and animal populations, along with accompanying environmental degradation and globalized trade and travel, enhance opportunities for transfer of pathogens within and between species. The resulting diseases pose enormous challenges now and for the future.
In most of the world, increased demand for animal protein has resulted in intensified commercial food animal production and/or expanded ‘backyard production’. Both types of production present unique challenges for disease emergence and control. It is inevitable that the world will continue to experience emerging disease outbreaks in the coming decades, and rapid development of animal vaccines can play a key role in controlling emerging diseases.
Vaccines for various diseases in pets and livestock are available, and routine vaccination can be done in consultation with veterinarians to make the world a better place to live in coexistence with other living creatures. (The contributor is Veterinary Officer, Veterinary Dispensary, Itanagar)