Modes of Virus Transmission

Virus transmission may be 'horizontal' or 'vertical'. The vast majority of transmission is horizontal, that is, between individuals within the population at risk. Modes of horizontal transmission of viruses can be characterized as direct contact, indirect contact, common vehicle, airborne, vector-borne, iatrogenic, and nosocomial. Vertical or transplacental transmission occurs between the mother and her fetus or newborn. Some viruses are transmitted in nature via several modes, others exclusively via one mode (see Table 2).

'Direct contact transmission' involves actual physical contact between an infected subject and a susceptible subject (e.g., kissing, Epstein-Barr virus, the cause of mononucleosis, biting (e.g., rabies); coitus (sexually transmitted viral diseases)). Indirect contact transmission occurs via 'fomites', such as shared eating utensils, improperly sterilized surgical equipment, or improperly sterilized non-disposable syringes and needles.

'Common vehicle transmission' pertains to fecal contamination of food and water supplies (e.g., norovirus diarrhea). Common vehicle transmission commonly results in epidemic disease.

'Airborne transmission' typically results in respiratory infections (and less typically in intestinal infections), but these infections may also be transmitted by direct and

Table 2

Examples of human and animal virus transmission patterns

Infectious agent/disease

Mode of transmission

Portal of entry

Influenza virus/influenza Rhinoviruses/common cold Rubella virus/congenital rubella




Hepatitis A virus/hepatitis

Variant Creutzfeldt-Jakob disease prion/prion disease (spongiform encephalopathy) Herpes simplex virus/genital herpes

Human immunodeficiency virus 1/acquired immunodeficiency syndrome (AIDS) Rabies virus/rabies Russian spring summer encephalitis virus/encephalitis Dengue viruses/dengue Sin Nombre and related viruses

Lassa virus

Ebola and Marburg viruses

Leukemia viruses/leukemias (proven only in animals)

Contact/direct/indirect via droplets and droplet nuclei Contact/direct/indirect via droplets and droplet nuclei and fomites Contact/direct/indirect via droplets and droplet nuclei Vertical/congenital Contact/direct/indirect via fomites Contact/direct/indirect via fomites Common vehicle/fecal contamination of water

Common vehicle/fecal contamination of food

Common vehicle/bovine spongiform encephalopathy prion contamination of beef or beef products Contact/direct (sexual)

Contact/direct (sexual), contact/direct

(blood) Vertical/congenital Zoonotic/contact/direct (saliva) Zoonotic/arthropod-borne

Zoonotic/arthropod-borne Zoonotic/contact/direct (rodent urine, saliva and feces) Zoonotic/contact/direct (rodent urine, saliva and feces) Zoonotic/reservoir host unknown; secondary cases contact/direct/ nosocomial and iatrogenic Vertical/germ-line

Respiratory tract

Respiratory tract

Respiratory tract

Transplacental Intestinal tract (oral) Intestinal tract (oral) Intestinal tract (oral)

Intestinal tract (oral)

Intestinal tract (oral)

Genital tract

Genital tract, bloodstream, transplacental, at birth and via breast feeding

Skin (bite wound) Skin (tick bite)

Skin (mosquito bite) Respiratory tract

Respiratory tract and intestinal tract (oral)

Index cases unknown, likely respiratory tract or skin and mucous membranes; secondary cases, contact and iatrogenic (injection) Transmitted as genetic trait indirect contact. Airborne transmission occurs via large droplets and via very small droplet nuclei (aerosols) emitted from infected persons during coughing or sneezing (e.g., influenza) or from environmental sources. Large droplets (>10 pm in diameter) settle quickly, but droplet nuclei evaporate forming dry particles (<5 pm in diameter) which remain suspended in the air for extended periods. Droplets may travel only a meter or so while droplet nuclei may travel over much longer distances.

'Vector-borne transmission' involves the bites of arthropod vectors (e.g., mosquitoes, ticks, and sandflies).

'Iatrogenic transmission' involves health care procedures, materials, and workers (e.g., physicians, nurses, dentists, and veterinarians).

'Nosocomial transmission' pertains to infections acquired while a patient, human or animal, is in hospital.

'Vertical or transplacental transmission' occurs from mother to fetus prior to or during parturition. Certain retroviruses are vertically transmitted in animals via the integration of viral DNA directly into the DNA of the germline of the fertilized egg. Other viruses are transmitted to the fetus across the placenta; yet others are transmitted when the fetus passes through the birth canal. Another vertical transmission route is via colostrum and milk. Vertical transmission of a virus may or may not be associated with 'congenital disease' (i.e., disease that is present at birth) which may be lethal (and the cause of abortion or stillbirth) or the cause of congenital abnormalities. The herpesviruses, especially cytomegaloviruses, and rubella virus cause important congenital diseases in humans, and pestiviruses, such as bovine viral diarrhea virus, in animals.

Was this article helpful?

+5 0
Swine Influenza

Swine Influenza

SWINE INFLUENZA frightening you? CONCERNED about the health implications? Coughs and Sneezes Spread Diseases! Stop The Swine Flu from Spreading. Follow the advice to keep your family and friends safe from this virus and not become another victim. These simple cost free guidelines will help you to protect yourself from the swine flu.

Get My Free Ebook


  • ari-pekka h
    What is the mode of transmission of viruses?
    11 months ago
  • Estelle
    Is transplancental direct?
    6 months ago
  • Nebay Amanuel
    How does a virus transmission to an infection?
    5 months ago
    What are transmissions of viruses and malware?
    5 months ago
  • mikolaj
    Is rabies vertical or horizontal transmission?
    5 months ago
  • libera maria
    What hepatitis viruses can be transmitted to humans by direct injection into the skin?
    4 months ago
  • cora
    How common does a virus change its mode of transmission?
    2 months ago
    How are the transmission of viruses and malware misused by people?
    2 months ago
  • melissa
    What are the modes of infection of influenza a and poliovirus?
    2 months ago
  • pamphila
    What is community gransmission of a virus?
    2 months ago
  • winta
    What is community transmission virus?
    1 month ago
  • damiana
    How does W32.Storm virus infect transport mode?
    1 month ago
  • Peter
    What is vertical transmission of a virus?
    1 month ago
  • aaron
    What is commuity transmission of a virus?
    1 month ago
  • james mickens
    What is sequential transmission of a virus?
    1 month ago
  • dewayne
    What is community based transmission virus?
    30 days ago
  • hessu
    What is community transmissuin?
    30 days ago
  • ponto gawkroger
    What is comunity transmission?
    29 days ago
  • generoso
    What is community trnsmission?
    29 days ago
  • Karoliina
    What is community transmission with viruses?
    29 days ago
  • primrose
    What are the transmission methods of viruses?
    27 days ago
  • Priamus
    What is cryptic virus transmission?
    27 days ago
  • frank
    What does communtiy transmission mean in infection control?
    27 days ago
  • medhanit
    What is community transmission of a viral?
    27 days ago
  • aziza
    What is community transmition of a virus?
    26 days ago
  • Senay Fethawi
    How does community transmission differ?
    26 days ago
  • jesse
    What is localized transmission of flu?
    25 days ago
  • Charles
    What does perso to person transmission mean in a virus?
    25 days ago
  • dale
    What is common vehicle transmission?
    24 days ago
    What is the mode of transmission for the selected virus?
    24 days ago
  • Lyla
    Can viruses transport airborne?
    24 days ago
  • arja
    How is a virus transmitted?
    23 days ago
  • deodata
    What is the Mode of transmission of corona virus?
    19 days ago
  • Doreen Barth
    Does a virus strengthen or weken on transmission?
    19 days ago
  • hiewan
    Does rain aid viral transmission?
    17 days ago
  • Danny
    What does virus transmisson look like?
    16 days ago
  • Eemil
    Can a virus change there transmission route?
    16 days ago
  • negassi
    What issecondary transmission viral?
    14 days ago
  • innes johnstone
    What are the common routes fro transmission fro viral infections?
    13 days ago
  • erik
    How to limit virus transmission?
    12 days ago
    What is the word for virus transmission types?
    12 days ago
  • christian
    How does rain affect virus transmission?
    12 days ago
  • Dennis
    What are all the possible transmission vectors for viruses?
    11 days ago
  • jani
    Does rain impede virus transmission?
    10 days ago
  • Olli
    What leads to community transmission of virus?
    10 days ago
  • Lawrence
    What is viral transmissions in regions?
    9 days ago
  • ranugad sackville
    Are there any viruses that are both airborne and droplet transmissions?
    9 days ago
  • Robert
    What type of vectors can aid in virus transmission Name at least two examples?
    8 days ago
  • hildigrim button
    Is virus droplet transmission?
    8 days ago
  • nicolas
    How are smear viral transmission caused?
    7 days ago
  • mariam
    What are the modes of infection by virus?
    6 days ago
  • Jill
    What is communal transmission?
    6 days ago
  • hilda lombard
    What do you call a virus that has multiple modes the transmission?
    4 days ago
  • yvonne schmidt
    How can material properties affect virus transmission.?
    2 days ago

Post a comment