Zoonoses disease-classification modes of transmission, Biology

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.

Posted Date: 9/20/2012 1:36:52 AM | Location : United States







Related Discussions:- Zoonoses disease-classification modes of transmission, Assignment Help, Ask Question on Zoonoses disease-classification modes of transmission, Get Answer, Expert's Help, Zoonoses disease-classification modes of transmission Discussions

Write discussion on Zoonoses disease-classification modes of transmission
Your posts are moderated
Related Questions
Proteolytic enzymes They catalyze the hydrolysis of peptide bonds in other proteins. In order to prevent them doing generalized damage to all cellular proteins, they are often

Non Symbiotic Nitrogen Fixers - Nutrient Cycles There are certain groups of free living bacteria both aerobic and anaerobic and blue green algae that fix nitrogen. Aerobic nit


In the sarcomere of a skeletal muscle, there are A. myosin molecules in the I band. B. both tropomyosin and myosin molecules in the region of the A band that is not in the H

Elaborate Immune Response system and their categories? The immune response is a group of defenses that the body has developed to combat disease-producing agents, or pathogens.

True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment

Q. Evaluate the texture of various foods? A number of instruments are available to evaluate the texture of various foods. Brief discussions on these instruments follow. Cons

How Lysosomal enzymes involved in the scavenging of aged Lysosomal enzymes are also involved in the scavenging of aged and damaged cells. In several diseased states and also by

Water is considered a universal solvent because- Select one: a. it can dissolve polar and non-polar compounds b. it can dissolve both positively and negatively charged ions a

What is the function of the myelin sheath? Do all axons present a myelin sheath? The function of the myelin sheath is to get better the safety and speed of the neural impulse t