Zoonoses disease-classification modes of transmission, Biology

Assignment Help:

Classification according to the modes of transmission


1.  Direct zoonoses: The direct zoonoses are those zoonoses that are transmitted from an infected vertebrate host to a susceptible vertebrate host by direct or indirect contact, by vehicle or by mechanical vector. Only a single vertebrate species is required to perpetuate the cycle and the agent itself undergoes little or no propagative changes during the transmission, e.g., rabies, anthrax, brucellosis, etc.
2.  Cyclo-zoonoses: These zoonoses require more than one vertebrate host, but no invertebrate host for completion of the causative agent’s development cycles. Most of the cyclo-zoonoses are cestode infections. The Taenia solium and Taenia saginata infections are obligatory cyclo-zoonoses, that is, man must be one of the vertebrate hosts in the cycle of the infections. Other cyclo-zoonoses, such as hydatid disease, are not obligatory. In these infections, man is sometimes involved but human involvement is an exception rather than the rule, e.g., hydatid disease, taeniasis, etc.
3.  Meta-zoonoses: The meta-zoonoses are transmitted biologically by invertebrate vectors. There is always an extrinsic incubation period in the invertebrate host  before the transmission of the causative agent to another vertebrate host. In the invertebrate, the causative agent may multiply and serve as a reservoir of infection (propagative transmission) or the agent may merely develop but not act as a reservoir of infection (developmental transmission). Depending upon the hosts required, meta-zoonoses are distinguished into four types.


Subtype I Requires one vertebrate and one invertebrate hosts, viz. sylvatic yellow fever.
Subtype II Requires one vertebrate and two invertebrate hosts, viz. paragonimiasis.
Subtype III Requires two vertebrate and one invertebrate hosts, viz. clonorchiasis. Subtype IV Requires transovarian transmission, viz. tick-borne encephalitis.


4.  Sapro-zoonoses:
The sapro-zoonoses are those infections which require a non-
animal site to serve either as a true reservoir of infection or as a site for an essential phase of development of their causative agents. The agent may propagate in the non-animal site (food, soil, plant), e.g., histoplasmosis or the agent may undergo essential development without propagation, e.g., Ancyclotoma brasiliense infection.


Related Discussions:- Zoonoses disease-classification modes of transmission

Embryology, Explain the gradient theoryof experimental embryology

Explain the gradient theoryof experimental embryology

What are the three main types of rna, What are the three main types of RNA?...

What are the three main types of RNA? What is meant by heterogeneous RNA? Messenger RNA, or mRNA, transfer RNA, or tRNA, and ribosomal RNA, or rRNA, are the three main kinds of

Name the enzyme present in saliva, Name the enzyme present in saliva and sa...

Name the enzyme present in saliva and say what type of food it acts on.   The enzyme in saliva is salivary amylase and it acts on starch.

AP Biology, Explain the difference between endoparasite, ecctoparasite, and...

Explain the difference between endoparasite, ecctoparasite, and parasitoidism

Explain main functions of organic molecules for living being, What are the ...

What are the major functions of the organic molecules for living beings? Organic molecules, such as proteins, lipids and carbohydrates, perform numerous functions for living or

Define criteria for assessment of vitamin d status, Define Criteria for Ass...

Define Criteria for Assessment of Vitamin D Status? You may recall the events involved in calcium homeostasis described earlier in this section. We studied that sufficient 25-O

Explain gastro-intestinal system, Explain G.I. (Gastro-Intestinal) system? ...

Explain G.I. (Gastro-Intestinal) system? A. Skeletal muscles directly control the movement of substances at the entrance of the G.I. system. B. Smooth muscles control the mo

How is the excretory system of molluscs characterized, Q. How is the excret...

Q. How is the excretory system of molluscs characterized? Molluscs have one or two pair of spongelike nephridia, similar to kidneys

Systolic versus diastolic failure, Systolic heart failure is a classic hear...

Systolic heart failure is a classic heart failure where the inotropic (contractile) state is impaired and the expulsion of blood is not adequate. So the main manifestations of syst

What is plutonium reprocessing, Q. What is plutonium reprocessing? Why is i...

Q. What is plutonium reprocessing? Why is it a big environmental issue? The Plutonium is the highly radioactive chemical element produced from uranium by nuclear plants. The Pl

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd