Better Animal Vaccines. Better Human Health.

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Humans interact daily with animals in our homes, outdoor activities, and even during our travels. Thereby, it is not surprising that there is a strong link between human and animal health.

According to the US Centre for Disease Control and Prevention, three out of five emerging infectious diseases of humans are caused by infections transmitted from animals.

Diseases and infections that are naturally transmitted between animals and humans are known as zoonoses and have been known to affect human health throughout history. Such diseases have an important impact on public health, the economy, and the conservation of wildlife.

Zoonotic diseases account for approximately 75 percent of emerging infectious diseases. Research shows that more than 800 human pathogens are zoonotic. The COVID-19 pandemic is the most prominent example of increasing human vulnerability to zoonotic diseases.

Exposure of humans to zoonoses occurs in different ways, from well-known or well-understood direct transmission routes, such as bites and rabies, to less obvious pathways. The risk factors or potential exposure routes are difficult to recognize and are interlinked in a relationship network between human beings, animals, and the environment. The most frequent sources of zoonoses transmission comprise food and contaminated water, vector insect bites and scratches, or bites from infected animals.

Because of the close connection between people and animals, it is important to be aware of the common ways people get infected with germs that can cause zoonotic diseases. These includes:

Direct contact: coming into contact with the saliva, blood, urine, mucous, feces, or other body fluids of an infected animal. Examples include petting or touching animals, and bites or scratches
Indirect contact: coming into contact with areas where animals live and roam, or objects or surfaces that have been contaminated with germs. Examples include aquarium tank water, pet habitats, chicken coops, barns, plants, and soil, as well as pet food and water dishes
Vector-borne: being bitten by a tick, or an insect like a mosquito or a flea
Foodborne: each year, people get sick from eating contaminated food. Eating or drinking something unsafe, such as unpasteurized (raw) milk, undercooked meat or eggs, or raw fruits and vegetables that are contaminated with feces from an infected animal. Contaminated food can cause illness in people and animals, including pets
Waterborne: drinking or encountering water that has been contaminated with feces from an infected animal

Practicing good personal hygiene, wearing protective clothing, maintaining healthy animals, and undertaking preventative treatments and vaccinations can minimize the risk of some animal-borne diseases infecting people

Animal vaccines play a key role in protecting animal health and contribute to public health through a safer food supply. They also help to reduce the need for antibiotics by preventing diseases that might otherwise require antibiotic treatment.

The use of vaccinations over the last century has prevented death and disease in millions of animals. Vaccinations are commonly used to protect pets from highly contagious and deadly diseases such as rabies, parvovirus, distemper, and hepatitis. Livestock and poultry like chickens, turkeys, pigs, and cattle are vaccinated to protect against diseases like rotavirus, E. coli, pinkeye, and tetanus.

The common types of animal vaccines include live (attenuated) vaccines, killed (inactivated) vaccines, and biosynthetic/ genetically engineered vaccines. The first-generation veterinary vaccines including inactivated and live-attenuated vaccines have gained considerable success in livestock and poultry industries.

However, these classical vaccines come with potential disadvantages. While inactivated vaccines fail to induce broad-spectrum immune responses, live-attenuated vaccines are associated with the risk of disease spread. The disadvantages of first-generation vaccines have been addressed in the second-generation (recombinant subunit vaccines) and third-generation vaccines (DNA, RNA, viral-vector-based, and chimeric vaccines). Another novel invention is marker vaccines that involve deletion mutants of wild-type pathogens.

Veterinary vaccines play equally vital roles in human well-being. The vaccines used in livestock and poultry help to maintain optimal animal health and improve the production of food. Collectively, these efforts lead to an increased supply of high-quality animal protein to the human population.

To meet the food demand of the fast-growing human population, a significant increase in animal food production is necessary. Besides protecting animals, veterinary vaccines reduce the risk of zoonotic diseases that jump from animals to humans through various routes of transmission.

Altered anthropogenic land use, environmental deterioration, and globalized trade and travel are the leading causes of pathogen spillover from animal to human populations, leading to the emergence of novel and deadly zoonotic diseases. The rapid development of novel veterinary vaccines could play a vital role in controlling the emergence of these diseases.

Veterinary vaccines developed against various pathogens help reduce pathogen shedding from infected animals, and thus, reduce the risk of foodborne diseases in humans. They reduce the need for antibiotics that are used to treat infections in animals. Excessive use of antibiotics can lead to the emergence of resistant bacteria in animals.

Consumption of raw or undercooked animal food may lead to the transfer of resistant bacteria from animals to humans. Consumption of vegetables, fruits, or water that are contaminated by animal feces can also infect humans with resistant bacteria. The use of vaccines to prevent infection instead of antibiotics reduces the risk of antibiotic resistance.

The success of inactivated and live-attenuated vaccines has enhanced livestock productivity, promoted food security, and attenuated the morbidity and mortality of various human, animal, and zoonotic diseases. However, these traditional vaccine technologies are not without fault. The efficacy of inactivated vaccines can be suboptimal with particular pathogens and safety concerns arise with live-attenuated vaccines.

Over the last three decades, veterinary medicine has spearheaded the advancement in novel vaccine development to circumvent several of the flaws associated with classical vaccines. These third-generation vaccines, including DNA, mRNA, and recombinant viral-vector vaccines, induce both humoral and cellular immune responses, are economically manufactured, safe to use, and can be utilized to differentiate infected from vaccinated animals.

DKSH provides physicochemical characterization solutions that have applications across numerous stages of vaccine development, from fundamental research to manufacturing and production. Find out more about the tools and resources to support your vaccine development.

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About the Author

Ruethaitip Tiratrakulvichaya has been with DKSH in Thailand since 2009. As the Application Manager for the Malvern Panalytical product range, she is responsible for technical and application support across Southeast Asia. With a background in food science and agroindustry, she is experienced in delivering training to both internal colleagues and external customers on how to operate and obtained the best data. Ruethaitip has extensive working knowledge in material characterization techniques including laser diffraction, dynamic light scattering, micro-calorimetry, size exclusion chromatography and morphological property.

Ruethaitip Tiratrakulvichaya

Material Science