PREVENTION AND CONTROL OF ZOONOSES TO ACHIEVE ONE WORLD – ONE HEALTH

PREVENTION AND CONTROL OF ZOONOSES TO ACHIEVE ONE WORLD – ONE HEALTH

1. Nagendra Reddy¹, G Shalini

Ph.D Scholar, Department of Animal Reproduction, Gynaecology and Obstetrics, CVAS, Mannuthy, Thrissur, Kerala

Corresponding author mail id: nagendrareddyy93@gmail.com

1. INTRODUCTION:

“Zoonoses” is derived from the Greek word “Zoon” which means animal, and “nosos” means illness.  Zoonosis is “any infection or disease that is transmissible naturally to humans from vertebrate animals” and that infection or disease is maintained in an animal (reservoir) population and serves as a continuous source of human infections (WHO,2020). Over 60% of diseases that affect humans have zoonotic origins (Taylor et al., 2001). This includes numerous types of bacteria, viruses, fungi, protozoa, parasites, and other pathogens (Morse et al., 2012). Three distinct typologies of interventions—animal-assisted activity (AAA), animal-assisted education (AAE), and animal-assisted therapy (AAT)—that involve experts with advancing levels of training and in which animals interact with people and patients more closely (ING, 2015). A possible epidemiological role for seemingly healthy animals implicated in AAIs could be in the asymptomatic carriage and possibly transmission of zoonotic infections to humans (Gerandi et al., 2018). This includes infections that human’s contract from direct contact with animals as well as infections that are spread indirectly through vector-borne, environmental, or food system pathogens. The emergence, reemergence, distribution, and patterns of zoonoses have been significantly influenced by a number of factors, including climate change, urbanisation, animal migration and trade, travel and tourism, vector biology, anthropogenic factors, and natural factors. The ongoing COVID-19 pandemic, which is “the most serious challenge of the post-war era due to the sudden halt in economic activity in both advanced and developing countries,” is the most striking and recent example of the global economic impact of a zoonosis. (UNIDO, 2020). A wide range of diseases with complex life cycles involving a variety of hosts and occasionally vectors or parasites are caused by zoonotic infections. These infections have a significant negative influence on both human and animal health locally and globally, as well as having a significant socioeconomic impact on endemic populations. This impact has recognised recently recognized and leads to global initiatives such as the ‘One Health’ approach, resulting in a thorough examination of the viewpoints of both humans and animals and robust cooperation between the environmental health sectors (CDC, 2020). In this article I would like to focus the etiological agents responsible for zoonoses and prevention and control of zoonotic parasites to achieve one world-one health concept.

2. Classification of Zoonoses:

The older classification of zoonoses includes the terms anthropozoonoses, zooanthroponoses, amphixenoses, and euzoonoses (Hubalek, 2003). Anthropozoonoses are animal diseases that can be transmitted to humans, such as rabies. Zooanthropozoonoses defined as those diseases that are transmitted to animals from humans such as tuberculosis in cat and monkey. Amphizoonoses are those diseases that can be transmitted in any direction (from human to animal and from animal to human) such as staphylococcal infection. For some parasitic diseases, Euzoonoses are those parasitic diseases where humans act as the obligatory host such as taenia solium and taenia saginata infections.

Based on etiology, zoonoses are classified into bacterial zoonoses (anthrax, brucellosis etc.), viral zoonoses (Ebola, avian influenza etc.,), parasitic zoonoses (toxoplasmosis, giardiasis, malaria etc.,), fungal zoonoses (ring worm), rickettsial zoonoses (Q-fever), chlamydial zoonoses (psittacosis), mycoplasma zoonoses (Mycoplasma pneumoniae infection), protozoal zoonoses and diseases caused by acellular non-viral pathogenic agents (Transmissible spongiform encephalopathies and mad cow disease) (Chomel, 2009).

3. Lists the major zoonotic diseases with their etiological agents, animal host, and major symptoms in humans (Rahman et al., 2020)

     3.1 Bacterial zoonoses:

Disease	Etiology	Animal Host	Major Symptoms, System or Organs Involved
Brucellosis	Brucella abortus Brucella melitensis, Brucella suis, Brucella canis,	Cattle, goats, sheep, pigs, and dogs	Fever usually high in the afternoon, back pain, joint pain, poor appetite, and weight loss
Anthrax	Bacillus anthracis	Cattle, horses, sheep, pigs, dogs, bison, elks, white-tailed deer, goats, and mink	Skin, respiratory organs or GI tract
Tuberculosis	Mycobacterium bovis, Mycobacterium caprae, Mycobacterium microti	Cattle, sheep, swine, deer, wild boars, camels, and bison	Respiratory organs bone marrow
Glanders	Burkholderia mallei	Horses, donkeys, and mules	Fever, sweating, muscle aches, chest pain, muscle tightness, and headache
Salmonellosis	Salmonella enterica, Salmonella bongor	Domestic animals, birds, and dogs	Enteritis
Pasteurellosis	Pasteurella multocida	Poultry, pigs, cattle, buffaloes, sheep, goats, deer, cats, dogs, and antelope	Fever, vomiting, diarrhea, and gangrene
Leptospirosis	Leptospira interrogans	Wild and domestic animals including pet dogs	Fever, abdominal pain,
Tularemia	Francisella tularensis	Rabbits, squirrels, muskrats, deer, sheep, bull snakes, wild rodents, beavers, cats, and dogs	Joint pain, diarrhea, and dry cough
Bubonic plague	Yersinia pestis	Rock squirrels, wood rats, ground squirrels, prairie dogs, mice, voles, chipmunks, and rabbits	Fever, chills, abdominal pain, diarrhea, vomiting, and bleeding from natural opening
Enterohemorrhagic Escherichia coli infections	E coli O157:H7	Cattle, sheep, pigs, deer, dogs, and poultry	Enteritis and Haemolytic–uremic syndrome (HUS)

 

3.2 Viral zoonoses:

Rabies	Rabies virus	Cattle, horses, cats, dogs, bats, monkeys, wolves, skunks, rabbits	Nervous system
Newcastle disease	Paramyxovirus	Poultry and wild birds	Conjunctivitis
Avian influenza	Influenza A virus	Ducks, chickens, turkeys, dogs, cats, pigs, whales, horses, seals, and wild birds	Flu like symptoms, diarrhea, and pneumonia
Ebola virus disease (Ebola Hemorrhagic Fever)	Ebola virus	Monkeys, gorillas, chimpanzees, apes, and wild antelopes	Fever, intense weakness, muscle pain, headache, sore throat, hemorrhage, vomiting, diarrhea, kidney, and liver failure
Chikungunya fever	Chikungunya virus	Monkeys, birds, and rodents	High fever, severe joint pain, muscle pain, and skin rash
Dengue fever	Dengue virus	Monkeys and dogs	High fever, skin rash, skin hemorrhage, and shock
Severe acute respiratory syndrome (SARS)	SARS coronavirus (SARS-CoV)	Bats, dogs, cats, ferrets, minks, tigers, and lions	influenza-like symptoms, fever, muscle pain, severe cases progress to a respiratory disease and pneumonia
Rift Valley fever	Rift Valley fever virus	Buffaloes, camels, cattle, goats, and sheep	Influenza- like fever, muscle pain, joint pain, and headache

 

3.3 Parasitic zoonoses:

Fascioliasis	Fasciola hepatica, Fasciola gigantica	Cattle, sheep, goats, and other ruminants	Intense internal bleeding, fever, nausea, swollen liver, skin rashes, and extreme abdominal pain
Hydatidosis	Echinococcus granulosus	Buffaloes, sheep, goats and adult stray or shepherd dogs	Hydatid cysts in liver, lungs, bones, kidneys, spleen, abdominal pain, and respiratory problem
Cryptosporidiosis	Cryptosporidium parvum	Cattle, sheep, pigs, goats, horses, and deer	Diarrhea lasting 3–14 days. Abdominal pain, nausea and malaise are frequent. Some patients have a slight fever
Cutaneous larval migrans	Ancylostoma braziliense	Dogs and cats	Subcutaneous tissue
Visceral larva migrans	Toxocara canis, Toxocara cati, and Ascaris suum	Birds, emus, cats, dogs, rabbits	Gastrointestinal, e.g., coughing, shortness of breath, fever, and abdominal pain

 

3.4 Acellular non-viral pathogenic agents:

Mad Cow Disease, also known as BSE (Bovine spongiform encephalopathy). In human known as Creutzfeldt–Jakob disease (CJD)

Prion protein

Cattle, sheep, goats, mink, deer, and elks

Ataxia, jerky movements, seizures, dementia, memory loss, and personality changes

 

3.5 Mycotic/fungal zoonoses:

Tinea/ringworm infection	Microsporum spp., Trichophyton spp.	All animals like cattle, sheep, goats, cats, and dogs	Skin lesions
Aspergillosis	Aspergillus spp.	All domestic animals and birds	Respiratory problems
Malassezia infection	Malassezia spp.	Dogs and cats	Pityriasis versicolor, seborrheic dermatitis, atopic eczema, folliculitis, and dandruf
Histoplasmosis	Histoplasma capsulatum var. capsulatum	Cats, dogs, rabbits, and rats	Often asymptomatic, fever, productive cough, chest pain, weight loss, hepatosplenomegaly, and hematologic disturbances
Coccidioidomycosis	Coccidioides immitis, Coccidioides posadasii	Dogs, horses, pigs, and ruminant	Hypersensitivity reaction, fever, erythema nodosum, erythema multiform, arthralgia, pleuritic chest pain, and dry cough

 

3.6 Protozoal zoonoses:

Trypanosomiasis	Trypanosoma brucei	Antelopes, cattle, camels, and horses	chronic and intermittent fever, headache, pruritus, lymphadenopathy, hepatosplenomegaly, and sleep disturbance
Leishmaniasis	Leishmania infantum	Cats, dogs, horses, and bats	Skin lesions, hepatosplenomegaly, and wasting
African sleeping sickness	Trypanosoma brucei	Antelopes, cattle, camels, and horses	High fever, headache, nausea, vomiting, and erythematous plaque formation
Toxoplasmosis	Toxoplasma gondi	Pigs, sheep, goats, poultry, and rabbits	Lymphadenopathy, fever, malaise, night sweats, myalgia, sore throat, and maculopapular rash
Giardiasis	Giardia lamblia	Dogs, cats, ruminants, and pigs	Diarrhea, abdominal cramping, bloating, flatulence, malaise, nausea, and anorexia

 

4. Reverse Zoonoses:

Zoonotic diseases that are transmitted to humans from animals and then back from humans to animals are referred as reverse zoonoses (Olayemi et al., 2020)

Examples of reverse zoonoses:

Agent	Human Disease	Animal Disease	Animal Affected
Infectious hepatitis	Hepatitis	Hepatitis	Nonhuman primates
Staphylococcus aureus	Furunculosis	Furunculosis, mastitis	Cattle
Streptococcus pyogenes	Pharyngitis, scarlet fever	Mastitis	Cattle
Giardia lamblia	Nausea, flatulence diarrhoea	None known	Beavers
Mycobacterium tuberculosis	Tuberculosis	Tuberculosis	Deer, dogs, elephants
Mumps virus	Mumps	Parotiditis	Dogs

 

For prevention and control of above zoonotic diseases the concept of one health – one world needs to be implemented all across the globe.

5. ONE HEALTH CONCEPT:

One Health (OH) is an integrated concept in addressing zoonotic diseases in improving the efficiency and effectiveness of zoonosis prevention and control at global health level. The One Health implementation takes into account ecological and social variables that contribute to the spread of zoonosis and offers complete solutions to evaluate and manage associated risks in various communities based on customs and locations (He et al., 2022).

Prevention is defined as inhibiting the entry of a disease agent into a specific population group or an individual. Efforts done to bring a disease problem down to a manageable level and keep it there are referred to as control. Eradication is the final step in a disease control program. It consists of the elimination of a disease producing agent from a defined population or geographical area. Prevention and control referred to as “primary prevention” and “secondary prevention”. Primary prevention is aimed at maintaining a healthy population i.e. preventing the occurrence of a disease. Secondary prevention attempts to minimize damage after disease has occurred. Rehabilitation referred to as “tertiary prevention” (Sohn et al., 2003).

The principles of zoonoses prevention control and eradication programs are focused mainly on breaking the transmission chain and the reservoir, transmission from the reservoir to the susceptible hosts, and the susceptible hosts are the factors involved (Martinma, 2007).

5.1 Reservoir Neutralization:

Source of zoonotic infection is the infected reservoir host and when the infection in the reservoir can be reduced or eradicated and the sources of infection progressively reduces and disappear.

Three methods used to neutralize the reservoir are removing infected individual, rendering infected individuals (non-shedder) and manipulating the environment.

• Removal of infected individual:

This can be achieved in two ways: test and slaughter and mass therapy (Martinma, 2007). Infection may be removed from an infected herd by testing and slaughtering. This method has been successfully used to control bovine brucellosis and tuberculosis as well as equine dourine and glanders. By sensitive and specific tests all infected animals need to be detected and erased without removing large numbers of false-positive animals. This method has been most effective with agents spread by direct transmission and with limited number of reservoir species are involved. Due to high cost this method has prevented its usage in many countries (Schellenberg et al., 2003).

The second method for neutralizing the reservoir is by mass therapy. Mass treatment is often limited to a local setting where all animals or humans who may be affected are treated without first undergoing tests to determine who is actually infected. One example of mass therapy is treating every dog in a certain area to prevent echinococcosis. (Acha and Szyfres, 2003). Mass treatment is reducing many of the issues related to human intestinal parasites. Diethylcarbarnazine is being used to control fascioloiasis (Ibrahim, 2010) and mass therapy has decreased the incidence of Schistosomiasis and African trypanosomiasis (McQuiston and Childs, 2002).

By decreasing the agent’s survivability in the vector of vehicle (food, water, soil, plants), environmental manipulation is a reservoir neutralisation technique intended to break the chain of transmission between the portal of exit of the diseased (shedder) host and the vulnerable host. Proper disposal of faeces (acting on the portal of exit), disinfection of faeces, and pasture rotation to reduce exposure of susceptible hosts (portal of entry) are a few parasite management measures that serve as examples of this strategy. (Martinma, 2007).

5.2 Reducing Contact Potential:

Reducing the likelihood of contact is a fundamental strategy for preventing the direct transfer of an infectious agent from an infected person to a vulnerable host. Two populations are taken into account in disease control: the known infected and the possibly exposed susceptible. Three strategies are employed: population control, quarantine of potentially infected individuals, and isolation and treatment of patients.

Isolation (Quarantine) of an infected ill animal has two advantages; it reduces the probability of contact with a susceptible lost and facilitates treatment and disinfection because because this strategy depends on early and accurate diagnosis from successful disease control programmes based on isolating and treating cases to prevent the spread of infectious disease agents, it has serious limitations and frequently fails (Acha and Szyfres, 2003).

The principles of isolation and quarantine should be kept in mind while placing animals in lab animal colonies, farms, or feedlots. This involves creating flow patterns that reduce the amount of contact between vulnerable, healthy animals and sources of infection. The idea of a “closed herd” involves the use of quarantine (Acha and Szyfres, 2003).

Programmes for population control are additional strategies for lowering contact. The main goals of leash rules are to prevent rabies and lessen faecal pollution. Although leash regulations seem reasonable in theory, public indifference, if not outright resistance, and a lack of enforcement have made them ineffective (McQuiston and Childs, 2002).

6. Increasing Host Resistance:

In addition to neutralization of reservoirs or contact reduction, zoonoses can be controlled by increasing host resistance to infection. The best course of action is to prevent infection, but in many cases, strengthening host resistance may merely moderate the severity of the illness without also strengthening resistance against infection (Martinma, 2007). However, chemoprophylaxis and immunisation are the two methods for boosting host resistance that are suitable for presentation. (Beers et al., 2006).

• Chemoprophylaxis:

Chemoprophylaxis aims to stop infection or lessen the illness’s severity, at the very least. Unlike immunisation, it is a passive method that only works as long as the medication does. On the other hand, an immunization’s active response might persist for months or even a lifetime. Usually, there is no reaction from the host. One example of the incorrect form of chemoprophylaxis, or no infection and no immunity, is the live anthrax vaccination given concurrently with penicillin prophylaxis (Jones et al., 2006). Chemoprophylaxis is usually used in the absence of any other, more potent host protection strategy. People’s antimalarial drug is one example. By inhibiting the erythrocytic stage of the malaria parasite, the drug lessens the severity of the disease’s effects but does not prevent infection (the mosquito injects sporozoites) (Berekeet,2008). Slow- or pulse-release boluses of oxfendazole have been shown in veterinary medicine to be beneficial in lowering pasture contamination and parasite gastroenteritis in cows. Among the most popular chemoprophylactic products for household animals are dog heartworm prevention pills and insect repellents that block arthropod vectors (Jones et al., 2006).

6.2 Immunization:

In addition to shielding vulnerable people from illness or infection, vaccines also stop the spread of infectious agents by building an immune system within the population. The stimulation of immunisation should be adequate to prevent both infection and disease in order to be most successful in reducing disease. If illness is the sole thing avoided in maintenance hosts, there is no decrease in the reservoir of infection. When comparing the percentage of the population that develops the necessary degree of protection to the resources used (vaccine, equipment, labour, promotion, etc.), the effectiveness of immunisation as a disease control strategy is evaluated (Ibrahim,2010). Immunisation is a normally very effective way to prevent disease; nonetheless, there can be delivery system failures, immune response failures, or iatrogenic errors that cause the failures (Jones et al., 2006).

7. Animal assisted interventions:

The purpose of AAIs is to expose stakeholders to possible infection risk. To ensure public health, zoonotic pathogen surveillance is required. This study looked into the existence of dermatophytes and other potentially zoonotic parasites in animals implicated in AAIs. AAIs may act as a direct cause of infection or as a result of environmental pollution. Active surveillance is therefore required, and the timing and planning of animal screenings should take the risk of exposure into consideration (Simonato et al., 2020). The study was conducted by simonato and coworkers on zoonoses linked to animal assisted interventions.

Figure 1: Number of study animals and their distribution in the main settings of animal-assisted interventions (AAIs) (Simonato et al., 2020).

Figure 2: Copromicroscopic results. Distribution of negative and positive (zoonotic and species-specific) results among the contexts of the AAIs (Simonato et al., 2020).

Figure 3: Copromicroscopic results. Distribution of negative and positive (zoonotic or species-specific) results in each animal species (Simonato et al., 2020).

Given the well-documented benefits of AAIs for humans and the growing national expansion of animal-related activities, it is important to consider the potential danger of pathogen exposure for both humans and animals. The gathered information emphasises the necessity of developing standards and instruments for evaluating the welfare and health of animals working in AAIs, taking into account generally asymptomatic animals that may have possible zoonotic infections. According to the increasingly significant idea of “One Health,” various protocols should be designed based on the actual risk of animal exposure to pathogens in relation to the lifestyle, management, and type of AAIs in which they are involved in order to guarantee the health of both humans and animals (Simonato et al., 2020).

8. CONCLUSION:

To achieve one world and one health for prevention and control of zoonoses it is better to know the etiology of bacterial, fungal, viral, protozoal and parasitic zoonoses, host diversity and symptoms needs to be known for effective diagnosis and treatment and their strategies for eradication, control and preventive measures like reservoir neutralization, reducing contact potential, quarantine, chaemoprophylaxis, immunization needs to be followed and preliminary survey in animals involved in AAIs represents a starting point for further investigation.

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