2. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Harmful Animals are those that cause injury to plants and domestic animals. Human beings are affected directly or through bites or stings or by transmission of various kinds of pathogens. Disease Causing organisms Some insects are injurious to man as vectors of human diseases. Through the ages millions of people have died of diseases transmitted by insects. There are a number of insect- borne diseases, and they may be transmitted in different ways.

3. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. House Fly are cosmopolitan in distribution. They are closely associated with humans and thrive best where people are careless in the disposal of wastes. Adult flies are non-parasitic, They feed on all kinds of decaying and decomposing matter House Fly (Musca domestica)

4. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. House Fly (Musca domestica) It is an important mechanical vector in the transmission of diseases like Typhoid (salmonella typhosa – a bacterium) Dysentery (Entamoeba histolytica) and Cholera (Vibrio sps ).

5. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. House fly control is normally done in 3 different ways, namely sanitary, mechanical and chemical methods. Population of houseflies can be controlled by proper disposal of manure, garbage, sewage,food waste, human excreta and other organic materials. Mechanical practices such as screening, using of traps or sticky paper or baits can be valuable in excluding houseflies. Insecticide may be used against larvae. Spraying with 2 % malathion 1% chlodane or lindane, tremephos are effective. House Fly (Musca domestica)

6. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies.

7. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Sand flies (phlebotomus papatasi) These flies are 4 mm long. Only the female possess piercing – sucking mouth parts and are haematophagous. The males are non parasitic, feeding on moisture. They are small slender insects with hairy bodies. Through biting this fly transmits the disease called kala – azar. The causative organisms is Leishmania, a parasitic protozoan.

8. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. During the day time the flies remain hiding. At night they come out to feed. The sand fly attacks during night times. The insect sucks the parasite from an infected person, along with blood. Inside the body of the fly, the parasite undergoes changes. When an infected fly bites man, the parasites pass into the blood and fresh infection is effected. The parasite mostly concentrate in the capillaries of spleen, liver and bone marrow. The disease is characterized by the symptoms like anaemia and emaciation. Sand flies (phlebotomus papatasi)

9. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. CONTROL: spraying of 5 % DDT / BHC easily kills the flies. The pyrethrum ointment used on exposed part of the body works as a repellent. Sand flies (phlebotomus papatasi)

10. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Rat flea (xenopsylla cheopis) The insect parasite, xenopsylla cheopis is commonly known as the Asiatic rat flea. Both male and female take in the bacillus pasteurella pestis from infected rats during feeding. This rat – flea is responsible for the transmission of plague from man to man, or from rat to man. When this bacterium is introduced into the skin, the lymph glands become inflamed. This is known as bubonic plague.

11. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. The bacilli become established in the victims blood. The condition is then referred to as septicemic plague. If the victims lungs become involved, it is referred to as pneumonic plague. Rat flea (xenopsylla cheopis)

12. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. When the rat flea sucks the blood of man or a rat infected with plague, the bacilli enter in to its stomach and grow there into large numbers. The flea thus heavily laden with the bacilli, may bite a healthy man and introduce the bacilli in to the wound and cause infection. The bacilli are deposited by the flea on the skin along with the faeces. The bite of the flea causes scratchings and the bacilli are introduced in to the blood when the skin scratched. Rat flea (xenopsylla cheopis)

13. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Destruction of rats and other rodents is an effective method. Dusting of 1 to 2 % chloradane, or 2% Y – BHC is very much effective in the elimination of fleas on the body of pet animals. Application of 5% DDT is recommended for spraying at the time of the spread of plague in all the areas. Rat flea (xenopsylla cheopis)

14. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies.

15. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. (Pediculus humanus) Human Louse (Pediculus humanus) Disease parasite Relapsing feverBorrelia sp TyphusRickettsia sp Trench feverRickettsia sp Louse is a blood sucking ecto-parasite of man.  human louse is a major vector for three important human diseases: relapsing fever, typhus fever and trench fever. Wearing clean clothes, and having regular bath avoids infection.

16. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies.

17. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Mosquitoes Mosquitoes are cosmopolitan in distribution. They are nocturnal in habit and are found in abundance in damp, marshy lands near stagnant water. Only female mosquitoes are adapted to suck the blood of human beings and function as carrier of viral, protozoan and nematode diseases.

18. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Culex filariasisCulex mosquitoes serve as the vectors for filariasis or elephantiasis. wuchereria bancroftiThis disease is caused by the nematode parasite, wuchereria bancrofti. It is commonly known as filarial worm. It is found in the lymphatic vessels and lymph glands of man. The female worms give birth to living embryos known as microfilariae.

19. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Culex The microfilariae normally circulate at night (10 to 2AM) in the peripheral blood. At that time they are ingested by the mosquito along with blood, the mosquito is not just a mechanical carrier of the parasite. When the infected mosquito next bites another person, the larvae penetrate the superficial skin to find their way in to the lymphatic vessels, and attain sexual maturity. In severe infection the adults cause blocking of lymphatic system which results in the enlargement of legs, arms scrotum, and mammary glands. elephantiasis.It is known as elephantiasis.

20. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Anopheles The Anopheles mosquito transmits plasmodium, a causative protozoan for malaria.

21. Prepared by T. Madhavan & K. Chandrasekaran, Lecturers in Zoology, Directorate of School Education., Pondicherry. An Illustration for the students who aspire for medical studies. Aedes The Aedes transmits yellow fever through a virus.