Lesson 10 - Vector, and Zoonoses Control, & Air, Radiation, and Noise Pollution

Zoonosis

Any infectious disease which animals can transmit to human beings

Virchow (1855)

used zoonosis as a synonym for infections by contagious animal poisons

False

pathogenic species responsible for zoonotic diseases can survive and multiply even without the presence of man

T or F?

pathogenic species responsible for zoonotic diseases cant survive and multiply without the presence of man

Zoonosis

Can be caused by viruses, parasites, bacteria, and fungi

Reverse Zoonosis
Emerging Zoonosis

Types of Zoonosis

Reverse Zoonosis

Infectious disease of people occasionally transferred to animals and then transferred back to people

Reverse Zoonosis

People → Animals → People

Reverse Zoonosis

From the word "reverse", it goes back where it comes from

Tuberculosis
Mumps
Streptococcus pyogenes
Infectious Hepatitis
Corynebacterium diphtheriae

Reverse Zoonosis examples

Streptococcus pyogenes

A bacterium that causes various infections to humans such as tonsillitis, pharyngitis, cellulitis, etc

Emerging Zoonosis

Zoonosis that is newly recognized or newly evolved or that has occurred previously but shows an increase in incidence or expansion in geographical, host, or vector range.

Emerging Zoonosis

It existed, then disappeared, then returned with an increase no. of incidents of the disease

Bird Flu
AIDS
Mad Cow Disease
Nipah Virus
SARS-COV-2

Recent Emerging Zoonotic Diseases:

Environmental change
Human and animal demography (statistics)
Pathogen changes
Changes in farming practice
Social and cultural factors such as food habits

FACTORS INFLUENCING ZOONOSES

Viruses

are among the most prominent examples of emerging pathogens because of their ability to adapt quickly to changing environmental conditions

Aerosols
Oral
Direct Contact
Fomites
Vector-borne

TRANSMISSION ROUTES OF ZOONOTIC DISEASES

Aerosols

Occur when droplets are passed through the air from an infected animal and are inhaled in by a person

Oral

Ingestion of contaminated food or water with the pathogen

Direct Contact

Coming into contact with saliva, blood, mucus, feces, or other body fluids of an infected animal

Fomites

An inanimate object that can carry a pathogen from an animal to a person or from a person to another

Fomites

In the case of Zoonotic disease, it can be from animals like the wool of the sheep that is used to make clothes.

Fomites

If not treated or disinfected properly, it can carry the pathogen and infect humans

Vector-borne

Bitten by a tick or insect

Aedes aegypti

Dengue

female Anopheles

Malaria

9 out of 10

____ out of _____ leading causes of morbidity can be zoonotic.

E. coli (Escherichia coli) causing UTI (Urinary Tract Infection)

may come from meat and animals, as stated in a European Journal of Clinical Microbiology.

Zoonotic type of TB (tuberculosis)

is a form of tuberculosis in people caused by bacteria known as Mycobacterium bovis which belongs to the mycobacterium tuberculosis complex.

Cattle (According to WHO)

most important reservoir for Mycobacterium bovis in relation to zoonotic exposures to humans.

H1N1 Influenza Virus

caused 1918 Flu Pandemic

1918 Flu Pandemic

An unusually deadly influenza pandemic lasting from January 1918 to December 1920

1918 Flu Pandemic

It infected 500M people

1918 Flu Pandemic

Death Toll: 17M-50M

H1N1 influenza virus

1918 Flu Pandemic Caused by _____________ believed to be of avian (birds) origin

Influenza A (H2N2) / Asian Flu Virus

caused 1957 Asian Flu

Also of avian origin

1957 Asian Flu

Caused by a virus known as Influenza A subtype H2N2 or Asian Flu virus

1957 Asian Flu

Death Toll: 2M worldwide

Influenza A (H3N2) Virus

caused 1968 Flu Pandemic (Hong Kong Flu)

1968 Flu Pandemic (Hong Kong Flu)

Caused by an Influenza A (H3N2) virus comprised of 2 genes from an avian influenza

1968 Flu Pandemic (Hong Kong Flu)

Death toll: 1M worldwide

HIV/AIDS Pandemic (1920-Present)

Scientists identified a type of chimpanzee in Central Africa as the source of HIV infection in humans

HIV/AIDS Pandemic (1920-Present)

Death Toll: 32M

75.7M

__________ people have been infected with HIV since the start of its epidemic up until 2019

Prevention
Control Efforts
Prevention and Control
Eradication
Note

PRINCIPLES OF ZOONOSES PREVENTION,
CONTROL AND ERADICATION

Prevention

Defined as inhibiting the introduction of a disease agent into an area, a specific population group, or an individual

Control Efforts

Consists of steps taken to reduce a disease problem to a tolerable level and maintain it at the level.

Control Efforts

In this case, since it was not prevented (it already happened), then you just have to control it.

Control Efforts

Takes steps in reducing a disease to a certain tolerable level and maintain it there.

Prevention and Control

sometimes referred to as Primary Prevention and Secondary Prevention

Primary Prevention

Aimed at maintaining a healthy population.
Like preventing the occurrence of a disease.

Secondary Prevention

Attempts to minimize damage after a disease has already occurred.

Eradication

The final step in a disease control program; it consists of the complete elimination of a disease-producing agent worldwide.

breaking the chain of transmission at its epidemiologically weakest link.

The basic principles of zoonoses prevention, control, and eradication programs are

the reservoir
transmission from the reservoir to the susceptible hosts
the susceptible hosts

3 factors are involved in breaking the chain of transmission

Reservoir Neutralization

Ultimate Source of Zoonotic Infection: the infected reservoir host

Removing infected individual

Rendering infected individuals or individuals as "non shedder" or not shedding the virus or organism to the environment.

Manipulating the environment

3 methods used to neutralize the reservoir are

Reducing Contact Potential

In disease control, two populations are considered, the known infected and the potentially exposed susceptible

Reducing Contact Potential

Like in COVID now, we consider known infected and also the people who have been in contact with or exposed to these known infected people.

Isolation and treatment of cases
Quarantine of possibly infected individuals
Population control

3 methods are used for Reducing Contact Potential

Isolation

is designed to keep the agent in.

Quarantine

is designed to keep the agent out.

Increasing Host Resistance

Reduction of stress, by providing improved shelter and nutrition is not only an end but is also a means to reduce the ravages of epidemics by increasing the survival ability of the affected population.

Increasing Host Resistance

Eating healthy, taking vitamins, exercise and getting enough sleep helps to boost the immune system, thereby increasing the resistance of the host.

Chemoprophylaxis

It is a passive means of increasing host resistance, to prevent infection or at least reduce the severity of the disease.

Chemoprophylaxis

It is used when a person is accidentally exposed to an agent known to be susceptible to a drug.

Chemoprophylaxis

Administration of a drug or medication to prevent the development of a disease or infection or at least reduce its severity.

Immunization

To protect susceptible individuals from infection or disease

Immunization (Herd Immunity)

To prevent transmission of infectious agents by creating an immune population.

Herd Immunity / Population Immunity

The indirect protection from an infectious disease that happens when a large part of the population is immune to a certain disease

Herd Immunity / Population Immunity

Which is done either through vaccination or immunity developed from passed infection.

Herd Immunity / Population Immunity

Although not every single individual may be immune, the group as a whole has protection.

Surveillance
Control in animals
Control of infectious media
Prevention in man

Operational Policies have been recognized as Suitable and Effective Methods of Zoonosis Control

Surveillance

Testing of accessible animals and biological materials which are essential in order to assess the presence of a disease and to establish the pathogen involved.

Surveillance

Slaughterhouse surveys are important in controlling certain diseases, such as brucellosis (animal reservoirs are cows and pigs).

Surveillance

Isolation and typing of the zoonotic agent is needed in several infections.

Control in Animals

To minimize the risk of transfer or introduction of zoonotic agents through the movement of animals, quarantine is strongly advocated.

Test and destruction

___________ of diseased or infected animals is often recommended to control certain zoonoses

Test and segregation

__________ of infected stock is recommended for other zoonotic infections such as leptospirosis.

Leptospirosis

bacterial disease that affects humans and animals. It is caused by bacteria of the genus Leptospira

Immunization of exposed animals

can be extremely effective. Vaccination campaigns may greatly assist in the control of a number of different zoonoses.

Treatment of sick and infected animals

proves valuable measures in combating some infections.

Restriction of animal movements

is an effective policy in dealing with zoonoses.

Control of animal populations

is an essential component of any program aimed at minimizing the spread of infections

Man

[Prevention in Man]

is the final and most important consideration and special priority must be given in all programs to secure better health welfare standards for human communities.

Occupational health education

is directed specifically at categories of workers especially prone to certain zoonoses

Vaccination

is especially effective in protecting at risk categories against zoonoses

Post-exposure treatment

is sometimes imperative (a must) as in the case of rabies infection

Proper food hygiene

especially regarding food of animal origin (e.g. meat products, poultry, etc.)

Vectors

These are living organisms that can transmit infectious pathogens between humans, or from animals to humans.

Vectors

Many of these are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit into a new host, after the pathogen has replicated.

Vectors

Often, once a vector becomes infectious, they are capable of transmitting the pathogen for the rest of their life during each subsequent bite/blood meal

Vector-Borne Diseases

These are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors

Vector-Borne Diseases

Vectors are the one that carries the disease from infected animals to humans or possibly to other animals

Vector-Borne Diseases

They account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually

Vector-Borne Diseases

These vector-borne diseases affect hundreds of millions of people worldwide.

protective measures and community mobilization.

many of these vector-borne diseases are preventable through

Malaria

A parasitic infection transmitted by female Anopheline mosquitoes.

Malaria

It causes an estimated 219 million cases globally, and results in more than 400,000 deaths every year.

Malaria

Most of the deaths occur in children under the age of 5.

Dengue

It is the most prevalent viral infection transmitted by Aedes mosquitoes.