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Contact transmission

Contact transmission includes direct contact or indirect contact. Person-to-person transmission is a form of direct contact transmission . Here the agent is transmitted by physical contact between two individuals ( [link] ) through actions such as touching, kissing, sexual intercourse, or droplet sprays . Direct contact can be categorized as vertical, horizontal, or droplet transmission. Vertical direct contact transmission occurs when pathogens are transmitted from mother to child during pregnancy, birth, or breastfeeding. Other kinds of direct contact transmission are called horizontal direct contact transmission . Often, contact between mucous membranes is required for entry of the pathogen into the new host, although skin-to-skin contact can lead to mucous membrane contact if the new host subsequently touches a mucous membrane. Contact transmission may also be site-specific; for example, some diseases can be transmitted by sexual contact but not by other forms of contact.

When an individual coughs or sneezes, small droplets of mucus that may contain pathogens are ejected. This leads to direct droplet transmission , which refers to droplet transmission of a pathogen to a new host over distances of one meter or less. A wide variety of diseases are transmitted by droplets, including influenza and many forms of pneumonia . Transmission over distances greater than one meter is called airborne transmission .

Indirect contact transmission involves inanimate objects called fomites that become contaminated by pathogens from an infected individual or reservoir ( [link] ). For example, an individual with the common cold may sneeze, causing droplets to land on a fomite such as a tablecloth or carpet, or the individual may wipe her nose and then transfer mucus to a fomite such as a doorknob or towel. Transmission occurs indirectly when a new susceptible host later touches the fomite and transfers the contaminated material to a susceptible portal of entry. Fomites can also include objects used in clinical settings that are not properly sterilized, such as syringes, needles, catheters, and surgical equipment. Pathogens transmitted indirectly via such fomites are a major cause of healthcare-associated infections (see Controlling Microbial Growth ).

Photo of person kissing a child and one of person playing arm wrestling with a child.
Direct contact transmission of pathogens can occur through physical contact. Many pathogens require contact with a mucous membrane to enter the body, but the host may transfer the pathogen from another point of contact (e.g., hand) to a mucous membrane (e.g., mouth or eye). (credit left: modification of work by Lisa Doehnert)
Photos of person touching doorknob, towel on a hook, and end of a syringe.
Fomites are nonliving objects that facilitate the indirect transmission of pathogens. Contaminated doorknobs, towels, and syringes are all common examples of fomites. (credit left: modification of work by Kate Ter Haar; credit middle: modification of work by Vernon Swanepoel; credit right: modification of work by “Zaldylmg”/Flickr)

Vehicle transmission

The term vehicle transmission refers to the transmission of pathogens through vehicles such as water, food, and air. Water contamination through poor sanitation methods leads to waterborne transmission of disease. Waterborne disease remains a serious problem in many regions throughout the world. The World Health Organization (WHO) estimates that contaminated drinking water is responsible for more than 500,000 deaths each year. World Health Organization. Fact sheet No. 391 —Drinking Water. June 2005. http://www.who.int/mediacentre/factsheets/fs391/en. Similarly, food contaminated through poor handling or storage can lead to foodborne transmission of disease ( [link] ).

Questions & Answers

introduction to microbiology
Shweta Reply
Study the life of microorganisms present in the environment their survivals etc..
ayesha
Microscopic organisms, commonly known as microorganisms or microbes, are found all around us and even inside our bodies. The category 'Microbes' includes a massive range of organisms including bacteria, fungi, viruses, algae, archaea and protozoa.
Amre
fermented foods likely benefited ancestors to preserve foods and make other foods like milk, cheese, and bread using microbes.
Zinnia Reply
the evidence that I would support the statement regarding ancient people ideas that disease was transmitted by things they could not see is by the discoveries under a microscope. Many microbiologists have discovered certain diseases caused by microbes.
Zinnia
plz give the information about glyoxylate cycle
kamini Reply
what type of information?
Sapiens
I need medical microbiology mcqs books for Mbbs
Kisota
for pakistani mbbs or other?
Sapiens
what is microbial soup?
Osborn Reply
😃😂funny question isn't it?!!! sorry for inconvenience 😊
ayesha
most bacterial pathogens that cause disease in humans are classified in terms if their preferable ph as
Beesan Reply
what is micro
Kabul Reply
extremely small in size
Swetha
almost invisible to the naked eye
Peter
thanks
Sadiq
uwc
Peter
invisible sized objects
Sivasri
invisible sized object or specimens.which is used to see in only the microscope that specimens or objective called the micro
Sivasri
small organism that can be seen by use of Microbes
Manyang
why do you need to study microorganisms
Sala
what is microbiology?
Green Reply
microbiology is a branch of biology .it deals with the study of microorganisms life cycle , uses, disadvantages,and it impact in any other fields .which is used to view in microscope .
Sivasri
Microbiology is the study of microorganisms, those being unicellular, multicellular, or acellular. Microbiology encompasses numerous sub-disciplines including virology, bacteriology, protistology, mycology, immunology and parasitology. 
Raj
In short , it is the study of micro organisms and types , characteristics.
Kaviya
can you explain the structure of rna in detail
Dhanalakshmi Reply
RNA is of many types....like mRNA,tRNA,rRNA,snRNA,guideRNA..etc .
Swetha
but generally RNA is single stranded
Swetha
It contains adenine guanine cytosine , instead of thymine it contains uracil.
Swetha
ribonucleic acid present in RNA.. where as in DNA it is deoxyribonucleic acid...and ribonucleotide is present in RNA
Swetha
RNA is a blue print of DNA. it has the information from DNA....and we can predict the base panirs in DNA if we have the RNA....copy of that DNA
Swetha
can either have positive or negative polarity
Ernestine
Diatoms need..... With the help of which they can construct their beautiful cell wall
Prathmesh Reply
Microbial growth curve shows a.... Curve.
Shambhuraj Reply
diminishing curve
Oluwapamilerin
It represents the decreasing growth of an organism.
Swetha
what is meant by reverse isolation in tuberculosis treatment?
Swetha Reply
why do we study microbiology
HABIBA Reply
Microbiology is the way of gaining knowledge about those organisms which are surround us but we can't see them with our naked eye,such organisms called microorganisms..We can see them only under microscope.
ayesha
from our birth to death microorganisms are with us in the environment as well as on our body which are called Microflora.
ayesha
Microfloras are non pathogenic
ayesha
what is microbiology
Anji Reply
It is the study of microorganisms and their structures functions and their interactions with environment ...
Swetha
it is the study of microorganisms which are invisible to backed eye but we can see them under microscope then microbiology is the study of microorganisms including their structures , functions,and their interactions with environment
Swetha
tq
Anji
tqq...not backed eye sorry nacked eye
Swetha
it's ok
Anji
where r u from
Anji
thank you
Swetha
from India
Swetha
which state
Anji
Hyderabad .
Swetha
so telugu vosthadhi kadha
Anji
chelusu nakku kochum
Swetha
thank you
Swetha
what is reverse isolation in tuberculosis treatment?
Swetha
Reverse isolation is used to protect you from germs when your immune system is not working properly. Germs can be carried on droplets in the air, medical equipment, or another person's body or clothing.
Kaviya
will you repeat this again?
Swetha
Reverse isolationis used to protect you from germs when your immune system is not working properly. Germs can be carried on droplets in the air, medical equipment, or another person's body or clothing.
Kaviya
kill you?
Swetha
Y
Kaviya
nothing to see the whole answer that is why I sent u like that then only I can see the full answer la
Swetha
What is allosteric site?
Hetshree Reply
I don't know how to explain but it's a deep concave site of an enzyme it's slightly or more slightly similar to the active site on an enzyme
ayesha
a site other than enzyme active site
Muhammad
describe the gram staining procedure as used in identification and classification of bacteria and it's interpretation
tabitha Reply
Gram staining method found by Hans Christian Gram. Classified into Gram Positive and Gram Negative Positive would be purple or blue stained bacteria Negative would be Pink or Red stained bacteria Both are observed under microscope This procedure performed on glass slides by making a smear of sample.
ayesha
Thanks.. nicely u defined
shamim
jazakallah Khair
ayesha
hmmm
shamim
Masha allah
Khamis
jazakallah Khair
ayesha
hi
Nafiu

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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