PARASITIC DISEASES OF SMALL ANIMALS ( 小动物寄生虫病学, Bilingual version) Professor Xing-Quan Zhu 朱兴全教授 Department of Parasitology College of Veterinary Medicine South China Agricultural University

Structure of the Lecture 2. How the subject will be taught? 3. What topics will be covered? 1. The objectives of the subject 4. How to assess the students’ performance?

6. Types of Parasites 7. Types of hosts 5. Animal Associations 8. Classification of Animals

Chapter One 兽医寄生虫学的范畴、地 位、作用和任务 Why this subject?

What is wrong with this cute puppy?

She is infected with Toxocara canis ( 犬 弓首蛔虫 )

She died…

Man She is infected with many adult worms of Toxocara canis ( 犬弓首蛔虫 )

Parasitic Diseases of Small Animals: A Very Important Subject 1.Important for animal health and welfare 2. Important for your career: Clinical problems, eg, Toxocariasis ( 弓首蛔 虫病 ), flea ( 跳蚤 )

3. Important for public health: Many are parasitic zoonoses ( 人兽共患病 ), eg, Echinococcus ( 棘球绦虫 ) ， Toxoplasma gondii ( 弓形虫 ) 4. Important for food safety: eg, Toxoplasma gondii ( 弓形虫 ); Clonorchis sinensis ( 华枝睾吸虫 )

The Objectives of the Subject: Two-fold: Learning parasitology and parasitic diseases of small animals while improving your English

15 lectures (44 lecture-hours) and 6 practice (26 lecture-hours) in bilingual form (English and Chinese) How the subject will be taught?

General Veterinary Parasitology What topics will be covered? Parasitism, types of parasites and their hosts, classifications, immunology, epidemiology, diagnosis and control measures, etc

Parasitic Cestodes ( 绦虫 ) Parasitic Protozoa ( 原虫 ) Parasitic Nematodes of Small Animals ( 小动物线虫 ) Parasitic Trematodes ( 吸虫 ) Parasitic Arthopodes ( 节肢动物 )

The lecturers are: Prof Xing-quan Zhu ( 朱兴全 ) Assoc Prof Ya-biao Weng ( 翁亚彪 ) Lecturer Zi-Guo Yuan ( 袁子国 )

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How to learn the subject efficiently? 1. Learn the textbook adequately 2. Preview relevant sections of the textbook before each lecture

3. Listen carefully and follow the lecturer’s flow of thoughts; concentrate on important topics… 5. Review relevant sections of the textbook after each lecture 4. Jot down ( 记下 ) as much as possible the lecture material

6. Ask the lecturers if you don’t get what you are supposed to learn. 7. Never pretend you understand if you actually don’t understand. 8. Pay more attention on practice and the cultivation of problem- solving capacity

How to assess if you have learnt what you are supposed to learn ( 如何考试 )? 1. Mid-term assignment ( 期中开卷作业, 30%) 2. End of term theory exam in English and Chinese ( 期末 “ 双语 ” 理论考试, 56%) 3. Practical examination ( 实践考试, 14%)

Chapter Two Types of parasites and their hosts and the relationships between them Introduction: Basic Principles and Concepts ( 基本原理及概念 ) Animal associations ( 动物间的关系 )

In nature, the majority of animals live independently of other organisms in their natural habitants, seeking their own food materials and utilizing free water and oxygen for their metabolic processes. Between some animals, however, a variety of associations have developed, and these may be broadly divided into two groups:

those between individuals of the same genotype ( 基因型 ) A: homogenetic associations ( 同源性关系） B ： heterogenetic associations ( 异 源性关系） – those between individuals of different genotypes.

Individuals of the same species may form loosely united communities, such as herds of cattle or flocks of sheep, while others, such as some species of ants and bees, may form elaborately organized communities in which individual members often exhibit considerable division of labour or specialization.

Commensalism ( 共栖或偏利共生 ) Terms such as commensalism ( 共栖或偏 利共生 ), symbiosis ( 共生 ), mutualism ( 互 利共生 ) and parasitism ( 寄生 ) have been widely used for various types of heterogenetic associations between different animal species. This term literally means ‘eating at the same table’

a type of loose association ( 一种松 散的关系 ) in which two animals of different species live together without either being metabolically dependent on the other, although one or both organisms may receive some benefit from the association

Mutualism ( 互利共生 ) and Symbiosis ( 共生 ) Mutualism is derived from the Latin mutuus (= exchanged), whereas symbiosis comes from the Greek symbioun (= to live together). symbiosis : a special kind of associations in which the participating species are dependent on each other for existence.

Mutualism: the association is not obligatory for existence. A typical example: the association between intestinal ciliates ( 肠道纤 毛虫 ) and their ruminant hosts These ciliates can help hosts digest plant fibre and produce nutrients and energy for the hosts and themselves

Parasites and Parasitism ( 寄生虫及寄生 ) The topics of the subject!!! Parasites An animal who lives completely at the expense of plants, animals or humans is defined as parasite.

Parasites have to solve several main problems in order to survive in the “struggle for life”: 1. They must develop successful strategies for host finding. 2. They must find methods for attachment and/or for partial or total penetration into ( 进入、穿入 ) their prospective hosts ( 可能的、未来的宿主 ).

3. They must become able to feed on the host’s tissues or fluids and must be able to metabolize ( 代谢 ) the nutrients ( 营养 ) obtained. 4. They must develop mechanisms ( 机制 ) to protect themselves from the attacks of their host’s defense systems ( 宿主的防卫 系统 ), e.g. mechanisms for immune evasion ( 免疫逃避机制 ).

5. Last but not least, parasites have to establish a high reproduction (fecundity) rate ( 高的繁殖率 )

parasitism is a unique animal association in which the parasite is not only in continuous, intimate association with its host, but is also metabolically dependent on its host to some degree, directly or indirectly.

Parasitism is a common mode of existence for a broad range of invertebrate organisms ( 无脊椎动物 ) such as arthropods ( 节肢动物 ), protozoans ( 原虫 ) and helminths ( 蠕虫 )(including trematodes, cestodes and nematodes, 吸虫，绦虫及线 虫 ), and can have a major socio-economic and/or public health impact. Examples: Ascaris ( 蛔虫 ); trichostrongyloids ( 毛圆线虫 )

Types of Parasites ( 寄生虫的类型 ) 1. Ectoparasites ( 外寄生虫 ): organisms that live on the outside of their hosts, usually attached to the skin, feathers, hair. Fleas ( 蚤 ), lice ( 虱 ) and ticks ( 蜱 )

2. Endoparasites ( 内寄生虫 ) ： living within their hosts. ie., in the gut, body cavity, lungs or other tissues. e.g., Trichinella spiralis ( 旋毛虫 )

Some parasites can be both: the itch mite Sarcoptes scabei ( 痒螨 ) 3. Facultative parasites ( 兼性寄生 虫 ): living either a parasitic or non-parasitic life. examples: larvae of some flies ( 某 些蝇的幼虫 ); strongyloides ( 类圆 线虫 )

4. Obligate parasites ( 固需寄生虫 ): Parasites which are obligated to live a parasitic existence and are incapable of surviving outside the host environment. Examples: trematodes ( 吸虫 ), cestodes ( 绦虫 ) and parasitic nematodes ( 寄生线虫 )

5. Stenoxenous parasites ( 专性寄 生虫 ): organisms that inhabit in only one particular species of host. For example, Eimeria species of chicken ( 鸡的艾美耳球虫 ) parasitise chickens only

6. Polyxenous parasites ( 多宿主 寄生虫 ): these are parasites that can infect more than one species of host. Trichinella spiralis ( 旋毛虫 ): can infect more than 100 species of animals

7. Temporary (intermittent) parasites ( 暂时性寄生虫 ): Parasites that live on the hosts for only a very short period of time in their life cycle. Examples: Mosquitoes ( 蚊 ) and bedbugs ( 臭虫 )

Example: Trichinella spiralis ( 旋毛虫 ) 8. Permanent parasites ( 永久性寄生 虫 ): parasites whose every life cycle stages are dependent on the hosts, and whose life will terminate ( 终止 ) if being separated from the hosts.

9. Opportunistic pathogenic parasites ( 机会致病性寄生虫 ): Example: Cryptosporidium( 隐孢子虫 ) parasites that do not cause any damages to the hosts under normal circumstances ( 正常情况下 ) but will become pathogenic ( 有致病性的 ) when the immune function of the hosts is attacked or compromised ( 受损 ).

10. Accidental or incidental parasites ( 偶然寄生虫 ): Example: Ascaris suum ( 猪蛔虫 ) in sheep parasites that enter or attach to the body of a host species other than its normal one