Zoonotic Infections: Threat To Human Health

Animal and human welfare are dependent on each other. Where animals have been source of so much benefits to humans, at the same time there are several biological disasters associated with existence if animals. Transfer of diseases from animals is majorly affecting human beings.

By Dr. Saba Mehnaz, Abdul Rauf

Significance and Major Zoonotic Threats:

Usually, the concept of zoonosis is mistaken only for small and mild infections but actually, the pandemic disease like HIV is believed to be zoonotic. Today one of the most challenging zoonotic infections includes tuberculosis caused by Mycobacterium tuberculosis and Mycobacterium bovis. A precise estimation illustrates that 0.3% population of USA is affected annually with tuberculosis, and Pakistan with population of about 216 million, is ranked 5th in the world in prevalence of zoonotic tuberculosis. Cases of tuberculosis have been reported mostly in people living in vicinity of animals or related to veterinary profession. Multi Drug Resistance Tuberculosis (MDRT) is horrible form of infection. MDRT is little diagnosed first or miss diagnosed and then subjected to long term use of ineffective antibiotics and infection is transformed into more chronic one with ultimate result of death.

Spores of Bacillus anthracis are resistant and even resilience and stay for probably 50 years in soil so any poultry or dairy farm suspected with anthrax infection will not allow at least coming 50 years of population to reside on the spot. Brucellosis is another big threat to animal as well as human health caused by Brucella species including B. abortus for cattle and sheep, B. melitensis for humans. This high-risk bio safety level 3 (BSL 3) organism is responsible for abortions in humans as well as animals. Another pregnancy hostile organism Toxoplasma gondii is transferred from cats even pet cats and a number of cases of abortions have been reported. Tetanus transferred from equines cost a number of lives yearly. Pakistan is one of the 34 countries that have not achieved the neonatal tetanus (NT) global elimination target set by the World Health Organization (WHO). One of the deadliest examples of zoonosis is severe acute respiratory syndrome (SARC), also called corona virus disease (COVID) has affected more than 200 million of people and more than 4 million causalities have been reported throughout the world according to world health organization.

Emerging Zoonosis:

One major issue related to zoonosis is emerging and reemerging of zoonotic infections. Actually, emerging zoonosis refers to the infections of animal origin which have started appearing in human beings but never observed before and re-emerging zoonosis with a little difference that it was observed but then number of cases reduced but recently number of cases are increasing again. Research shows that most of the emerging zoonotic infections are viral in nature. Best example of re-emerging zoonosis is spread of highly pathogenic avian influenza (HPAI). Where emerging zoonosis is an alarming sign for human health at the same time emerging reported anthroponosis e.g.  prevalence of hepatitis E and occurrence and prevalence of giardia in animals by eating fodder agitated by sewerage water is bad sign for animal health. 

Risk Factors of Zoonotic Infections:

Major risk factors responsible for spread and maintenance of zoonotic infections are negligence about infection, nature of infection i.e., bacterial or protozoal, modes of transmission i.e., direct transmission or vector borne, life cycle of infectious agent that assists in providing check point for survival i.e., if infective stage is controlled or destroyed, survival of infectious agent is in danger perhaps except for viruses. So, there is dire need to make people aware of health hazards associated with animals or working with or near animals.

Critical Control Point for Zoonotic Infections:

Farm workers should be provided and regulated about wearing personal protective equipment while working on the farm. Most of the orchitis cases in farm workers has been reported due to brucella species. Bio risk management should be strictly followed at farm. Entrance and exit should be monitored. Antiseptic and sterilized environment should be ensured.

Some seasonal changes should be kept in mind and prerequisites should be made accordingly like 2 weeks prior to rainy season, animals should be dewormed and even vaccination may be done against notorious or deadly worms like Fasciola hepatica that is equally dangerous for animals and humans. Farms should be constructed away from the human population to avoid zoonosis and it may prove a very positive step in this regard.

Control and Prevention of Zoonotic Infections:

Usually, biphasic methodology is adopted for resolution of the problem. One phase consists of immediate and urgent response against outbreak but second phase works on future prevention and eradication of the outbreak. The simplest example to be coded should be of SARC outbreak in 2020. At the peak of outbreak, medical staff took agent, modes of transmission, mechanism of disease and treatment under considerations but however, preparation of vaccine and full protocol for its eradication also took place parallel to immediate response. Vector borne zoonotic infections can be prevented by vector control that is somehow difficult so prophylaxis of infection is suggested. For example, during outbreak of endemic plaque in Madagascar 2017, 08 deaths were reported and it should be usual practice in Madagascar to use vector repellants in veterinary practice and use of prophylaxis therapy during suspected period of outbreak and in Pakistan, vaccination of pink eye in cattle and buffalo and foot rot in cattle, sheep, goat and buffalo should be practiced that are vector borne diseases. Proper veterinary assistance should be available when required, many animal health programs may be introduced where major zoonotic diseases may be addressed.

International Organizations:

If any zoonotic outbreak occurs in any region, relevant international institutes should be informed of it like Global Action and Response Network (GOARN) is working under World Health Organization (WHO) and reports WHO about any outbreak in any region of world especially of animal origin. International Organization for animal health (OIE) is also active and collaborates with WHO about health concerns.

 Major obstacles in control of zoonosis are lack of financial aid, under developed economy, lack of proper advanced techniques, negligence of institutions, lack of proper professional staff and management. Keeping in view above narrated picture, we may say that beneficial aspects of control and prevention of zoonosis have always been underestimated. It will not only make animals enjoy good health as well as humans and reduce the need of medical staff and hospital load.

In college of Veterinary and Animal Sciences Jhang, there is an efficient team of microbiologists, public health professionals and parasitologists who are continuously engaged in diagnosis and cure of major zoonotic infections. So, farmers and animal owners are advised to come and get up-to date health status of their animal about zoonotic infections and ensure their animal’s as well as their own protection.


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