1. Dirofilaria immitis, commonly known as dog heartworm, is a parasitic roundworm found in the hearts and associated blood vessels of domestic and wild canines. 2. The parasite has a complex lifecycle involving mosquitoes as an intermediate host. Microfilariae are transmitted between canine hosts when a mosquito takes a blood meal. 3. Adult heartworms can cause severe lung disease and heart failure in infected dogs if left untreated. Diagnosis involves blood tests and imaging exams like chest x-rays. Treatment aims to eliminate both adult worms and microfilariae.

1. PARAFILARIA & DIROFILARIA IMMITIS HEARTWORM

2. body-unsegmented--the bilateral symmetry covered by a typical cuticle which is formed by a hypodermis. pseudocoelomatic body cavity contains a complete digestive tract, the anus subterminally situated. food of various kinds (blood, body fluid, intestinal contents, mucus etc.) taken up by the species-specific mouth . the excretory system, if present, empties through an anterior, ventromedial porus. respiratory and circulatory systems are lacking. movements by contractions of the typically longitudinally oriented muscle cells with the fluid of the pseudocoel and the pressure of the cuticle working together as a hydrostatic skeleton. General morphology of Dirofilaria family -- 1

3. General morphology of Dirofilaria family-- 2 Male---- 12 to 16 cm long Slender , white in color 1.25 to 1.5 mm long esophagus Spirally coiled hind end bears small lateral alae 4 to 6 pairs of ovoid alae 1 pair—post cloacal 2 pairs --- lateral & posterior to cloacal opening 3 to 4 pairs – near the tip of tail Left spicule 0.342 to 0.375 mm long pointed Right spicule 0.19 to 0.229 mm long ends bluntly. Males are reffered as “pigtail ”.

4. General morphology of Dirofilaria family -- 3 Female-- 25 to 30 cm long Ovoviviparous – lay microfilaria Longer than male. Shows genital organs…vulva, vagina ,uterus etc. Microfilaria-- Accurately larvae are described on the basis of fixed points like NR nerve ring ; Ex.P excretory pore ; Ex C excretory cell ; G1 ; G2 ; G3 ; G4 genital cell 1, 2 , 3, 4 resp. ; A P anal pore ; L T C last tail cell FOR D. immitis [found in dog & % Distance from the Ant. End] 82 92.9 79.4 75.4 74.1 67.9 38.6 32.5 23.8 AP LTC G4 G3 G2 G1 EC EP NR

5. Morphology of D. immitis :

6. Dirofilaria immitis microfilaria. (From Soulsby, E.J.L. 1969). Dirofilaria immitis microfilaria morphology

7. Dirofilaria immitis - microfilaria Note the tapered anterior end. In most specimens you will see a straight body and straight or slightly curved) tail. The width is > 6 um.

8. Microfilaria Microfilarial stage as seen @ 400X magnification [wiki-image] 1 st stage microfilaria in blood smear.

9. Scanning electron micrograph of tail of D. immitis showing alae. Under electron microscope

10. Kingdom Animalia (animals) Eumetazoa (metazoans) Bilateria (bilaterally symmetrical animals) Protostomia (protostomes) Ecdysozoa Phylum Nematoda (nematodes) Class Secernentea Order Spirurida Superfamily Filarioidea Family Filariidae Genus Dirofilaria Species Dirofilaria immitis Systemic classification of D. immitis Kingdom: Animalia Phylum: Nematoda Class: Secernentea Order: Spirurida Family: Filariidae Genus: Dirofilaria Species: Dirofilaria immitis

11. Different species of Dirofilaria: Black bears Yamaguti [1941] D.Urci Subcut recoons Chandler[1942] D.Tenuis Subcut, IM CT, Pelvic region of wallabies & kangroo Linstow[1605] D. romeri Human Addario[1885] D. Conjuctivae Monkey Linstow[1899] D.Corynods Subcut tissues of dogs Railliet & Henry [1911] D. repens

12. Development ….1 The mosquito ingests microfilariae after a blood meal from a infected dog. The microfilariae develop into L2 in the malpighian tubes. Then L3 develop and enter the body cavity, the hemoceol. Development from the microfilariae to the L3 takes 15-16 days. The L3 escape in a pool of hemolymph as the mosquito inserts its labium into the definitive host, which is usually a dog. If its stylets are withdrawn, the L3 enter through the puncture wound made by the mosquito. The L3 will then molt into the L4 in the definitive host 0-14 days after infection. The L4 migrate to sub muscular membranes and subcutaneous tissue and remain dormant.

13. They molt into the L5 and migrate through venule walls and end up in the pulmonary arterioles and right heart of the definitive host. The L5 will mature into adults that will further migrate to the right ventricle or pulmonary artery 85-120 days after infection. The adult will reach maturity in a further 2-month period and shed microfilariae in the blood to begin the cycle all over again. The adults can remain in the heart or artery for up to 7 years. Microfilariae can remain in the circulation of the mosquito for up to 2 years. (Muro et al., September 1999; Soulsby, 1968) Development ….2

14. Life Cycle pattern of D. immitis Mosquito bites dogs with microfilaria in its blood After 24 hrs microfilariae in stomach of insect Next 24 hrs microfilaria migrate to malpighian tubules. Here they develop over next 15 – 16 days. This 16 days maturation process is as follows: 1 st 6 to 7 days – larvae inside the cells of tubules by 4 th day – infection in sausage stage i. e. 2 nd stage 220 µm x 20 to 25 µm sausage stage ultimately produce elongated sausage form where they measure 500 µm x 20 µm. Excretory & intestinal cells increase in this stage. This stage feeds on malphigian cells if insect & enters body cavity through haematophagus activity

15. Life Cycle of D. immitis

16. The male mosquito does not bite The female mosquito bites Male & female mosquito responsible for Heartworm Entomological sketches

17. A female mosquito blood feeding. Mosquitoes serve as intermediate hosts of other parasites such as Dirofilaria immitis the dog and cat heartworm and Plasmodium species causing malaria in humans and birds. They are also vectors of viruses causing yellow fever and encephalitis. Mosquito responsible for Dirofilariosis feeding on skin …..

18. PATHOGENESIS Circulatory distress , progressive endarteritis Cardiac dysfunction Pulmonatory hypertension --- narrowing of small peripheral pulmonary arteries Similar lesions in hepatic veins Compensatory hypertrophy of rt. Ventricle This leads to chronic passive congestion --- liver enlargement --- ascites --- --- peripheral edema Deep , dry cough Haemoptysis Decreased stamina , rib cage remains expanded , extra inspiratory efforts Emaciation In X-ray -------- main pulmonary artery – dilated In ECG ------ inverted T wave after exercise

19. THE ADVANCED SOROLOGICAL TESTS FOR HEARTWORM DISEASE 1) IFA for microfilarial antibody 2) ELISA for adult antibody 3) Adult antigen detection by ELISA and colloid gold. Diagnosis……1 Electrocardiogram Radiography Echocardiogram Tracheal Cytology

20. Diagnosis……2 SIMPLE BLOOD SMEAR TESTING WITH CONCENTRAION TECHNIQUES Clinical Signs of Heartworm Disease Acute Signs Convulsions Vomiting/Diarrhea Collapse Blindness Anorexia Tachycardia Syncope Chronic Signs Coughing * Dyspnea * Vomiting * Lethargy Weight loss

21. A, Thoracic radiograph from a cat with mild radiographic signs of heartworm disease. Note the right caudal pulmonary artery (arrow). The arrow is located in the ninth intercostal space, the site for comparison of the ninth rib with the pulmonary artery (right or left side). If the pulmonary artery is greater than 1.6 times the size of the rib, it is suggestive of heartworm disease (Schafer and Berry, 1995). B, Thoracic radiograph obtained from a more severely affected cat. Note the alveolar infiltrate in the caudal lung lobes. (From Schafer M, Berry CR: Cardiac and pulmonary artery mensuration in feline heartworm disease. Vet Radio Ultrasound 36:499, 1995.) Diagnosis from X-ray….[feline]

22. Ascites is a fluid build up in the abdomen seen in late stages of Heartworm Disease. Ascites Diagnosing the Canine Heartworm……

23. Worm load in the canine heart See the worms protruding out from ventricular walls to be more specific from Interventricular septum & from the bas of the heart. This is level 5 of worm load – the higher level.

24. Canine heart ….cut open See the length of worms. These are oriented from apex to the base. It gives idea about the morphology of worm. University of Kansas

25. ECG of Normal & Inverted T-wave Inverted T wave Normal T wave

27. Treatment Heart , liver , kidneys , lungs are assessed before treatment Infected dog is treated with adulticide anthelmintic 6 weeks later micrifilaricidal treatment is used Adiltcide Arsenical thiacetarsamide I/V dose 0.1 ml/0.45 kg twice a day for 2-3 days ( This is potential nephrotoxin , hepatotoxin ) Melasoprol 100 mg/kg adultcide Surgical ways ventricular puncture arteriotomy main trunk of pulmonary artery Microfilariacidal – dithiazanine iodide 2 mg/ .45 kg for 7 days in persistant cases ; dose is increased to 5 mg/ 0.45 kg (not to be used if case is having hepatoportal diseases ) Levamisole 10 mg/kg 15-20 days

28. Control Animals s/b indoors @ night & evening. Prophylactic medicine – thiacetarsamide Rx after every 6 months Regular checkup after 6 months DEC & styrylpyridinium DEC 5.5 mg/kg daily 2 months afer mosquito season ( dewarming is essential) Menbendazole 80 mg/kg daily for 30 days Avermactin B1a 0.2 mg/kg/day OR Melarsoprol 100 mg/kg/day (Menbendazole s/n/b used with this)

29. Zoonotic aspects of D.immitis D.immitis is not important from zoonotic point of view. However in some cases signs of respiratory infections are seen. But in most of such cases the parasite dies shortly as it enters the lung of the human being. The granuloma is formed around dead worms as it is being killed & absobed. Many times this granuloma resembles with lung cancer on X-ray & biopsy is done for confirmation. D. Tenuis ---- raccoons ---- eye infections D. Repens ---- dogs [Italy] ---- subcutaneous infections

30. PARAFILARIA Parafilaria multipapillosa (Condamne & Drouilly ; 1878) Found in equines Male 28mm Female 40-70mm Ant. End ----- large no of papilliform thickenings Found in sub-cut & IM CT -----Produce sub-cut nodules I/M host Haematobia atripalpis Parafilaria bovicola (de Jesus ; 1934) Haemorrhagic nodules on cattle & buffalo Adults ---- 13 rows of cuticular elevations @ ant. end. Remaining cuticule is transversely striated. Parafilaria antipini (Rukhiadev ; 1947) Indofilairia patabiramani (Alwar , Seneviratna , Gopal 1959) show same symptoms as Parafilaria bovicola (de Jesus ; 1934).

31. Life Cycle pattern of Parafilaria Dev. In musca spp. i. e. M. lusoia M. xanthomelas These feed on lesions Land on lacrimal glands or wound to infect host Treatment Nitroxynil 20 mg/kg repeated after 72 hrs High doses of levamisol , fenbendazole 4-5 days

32. References :- Helminthes of Domesticated Animals. [7 th edition] E J L Soulsby www.yahoo.com www.google.com www.wikipedia.com www.wikimapia..org Thank you… Sarang S. Desai V/05/0170 Guided by- Dr. Parampalle Department of Parasitology