Isospora and Sarcocystis PDF

ISOSPORA PREPARED BY: AND DR. SHIRLEY TANG SARCOCYSTIS GEE HOON  Diarrhoeal disease – Isosporiasis Important cause of diarrhoea amongst the immunocompromised esp. AIDS...

ISOSPORA PREPARED BY: AND DR. SHIRLEY TANG SARCOCYSTIS GEE HOON  Diarrhoeal disease – Isosporiasis Important cause of diarrhoea amongst the immunocompromised esp. AIDS patients ISOPORIASIS Previously included as an indicator disease for AIDS Two species i. Isospora belli (common) ii. Isospora natalensis 2 ISOSPORIASIS Naturally occurring infection in animals – eg. Dogs Distribution is cosmopolitan but usually underdiagnosed Transmission of infection through ingestion of mature oocysts either from human (I. belli) or animal sources. Fecal oral transmission through contaminated food or water 3 MORPHOLOGY OF OOCYST Sporulated (matured) oocyst is oval/elliptical Contains two sporocysts, each with four sporozoites. The oocyst is surrounded by a thin, smooth, two layered cyst wall 4  LIFE CYCLE Man gets infection by ingestion of food and water contaminated with sporulated oocyst in soil. Homoxenous – needs only one host to complete Schizogony (asexual) and gametogony (sexual) in host intestinal mucosa Unsporulated (immature) oocysts produced passed in feces 5  LIFE CYCLE Man gets infection by ingestion of food and water contaminated with sporulated oocyst. When a sporulated oocyst is swallowed, eight sporozoites are released from the two sporocysts in the small intestine and invade the intestinal epithelial cells. In the epithelium, the sporozoites transform into trophozoites, which multiply asexually (schizogony) to produce a number of (merozoites). The merozoites invade adjacent epithelial cells to repeat asexual cycle. 6  LIFE CYCLE Some of the trophozoites undergo sexual cycle (gametogony) in the cytoplasm of enterocytes and transform into macrogametocyles and microgametocytes. After fertilization, a zygote is formed, which secretes a cyst wall and develops into an immature oocyst. These immature oocysts are excreted with feces and mature in the soil 7 CLINICAL FEATURES Infection is usually asymptomatic. Clinical illness includes abdominal discomfort, mild fever, diarrhea and malabsorption. The diarrhea is usually watery and does not contain blood or pus and is self-limiting. However, protracted diarrhea, lasting for several years can be seen in immunocompromised persons, particularly in the HIV- infected. Extraintestinal infections such as involvement of biliary tract. 8 DIAGNOSIS Fluorescent stained smears: By auramine rhodamine stain (Fig. 7.11A) Autofluoresce can be seen under 330–380 nm ultraviolet filter. However, this property is not consistent like in Cyclospora Presentation Title 9 DIAGNOSIS 10 TREATMENT & PREVENTION Usually not required, Cotrimoxazole in serious cases Prevention: Good personal hygiene, adequate sanitation 11 SARCOCYSTIS 12 SARCOCYSTIS SPECIES Zoonotic parasite Infecting a wide range of domestic and wild animals, infection in human is relatively rare More serious in animals of veterinary importance Sarcocystis sp. Intestinal sarcocystosis: Muscular sarcocystosis: S. hominis (via cattle) and S. Unidentified species of Sarcocystis suihominis (via pig) collectively known as S. lindemanni 13 SARCOCYSTIS SPECIES Definitive and intermediate hosts are generally species-specific: Intestinal sarcocystosis in man: Caused by S. hominis and S. suihominis. Man acts as a definitive host. Cattles and pigs serve as intermediate hosts for S. hominis and S. suihominis respectively h Muscular sarcocystosis in man: Caused by S. lindemanni. Man acts as an intermediate host. Dogs and cats serve as defi nitive hosts.Humans are the : Definitive host of S. hominis and S. suihominis and Intermediate host for S. lindemanni. 14 SARCOCYSTIS SPECIES Definitive and intermediate hosts are generally species-specific: Intestinal sarcocystosis in man: Caused by S. hominis and S. suihominis. Definitive host: Humans Intermediate host: Cattles (S. hominis) and pigs (S. suihominis) Muscular sarcocystosis in man: Caused by S. lindemanni. Definitive hosts: Dogs and cats Intermediate host: Man 15 DEFINITIVE HOST infection takes place in the intestine (enteritis) infection with S. hominis or S. suihominis infection through eating raw or barely cooked beef (S. b) or pork (S. s) containing sarcocysts oocysts passed out in feces usually sporulated definitive hosts include human, dog, cat (usually predator or carnivore) 16 INTERMEDIATE HOST infection takes place in the striated muscle (miositis) infection with other species of Sarcocystis infection through ingestion of oocysts human, cattle, pig, rat (usually prey) 17 MORPHOLOGY It exists in three morphological forms: i. Oocyst ii. Sporocyst iii. Sarcocyst 18 MORPHOLOGY- OOCYST Found usually in the intestine of the definitive host. They sporulate within the lamina propria of the intestinal epithelium The sporulated oocyst is elongated, oval, colorless thin- walled. It contains two elongated sporocysts and each sporocyst contains four elongated sporozoites. 19 MORPHOLOGY- SPOROCYST From the sporulated oocyst, sporocysts are released and are excreted in the feces of definitive host. It is the infective form to the intermediate host. It is oval 9–16 μm size and contains four elongated sporozoites. 20 MORPHOLOGY- SARCOCYST Sarcocysts (muscular cysts) Found in the cardiac and skeletal muscles (of diaphragm, oesophagus) of the intermediate host It is elongated, found longitudinally along the muscle fibre It has a thick cyst wall. The cyst is divided into many compartments that contain numerous banana-shaped bradyzoites or metrocytes 21 LIFE CYCLE Complicated with alternation of hosts. 2 hosts are needed to complete life cycle, the definitive and intermediate hosts. Human can act as both definitive and intermediate host depending on what species of Sarcocystis involved 22 LIFE CYCLE Sarcocystis has an obligatory two-host (prey-predator) life cycle. As a rule: ▪ Sexual cycle takes place in the intestine of the carnivorous/predator animal (definitive host) ▪ Asexual cycle takes place in the muscle and other tissues of the herbivorous/ prey animal (intermediate host) 23 LIFE CYCLE 24 CLINICAL FEATURES Intestinal infection Occurs following ingestion of improperly cooked beef or pork containing the sarcocyst. Usually asymptomatic or causing mild abdominal discomfort, nausea and diarrhoea. Eventually ends up in passing out oocysts in feces. 25 CLINICAL FEATURES Muscular infection Occurs following ingestion of oocysts. Usually asymptomatic. Painful muscular & subcutaneous inflammatory swellings in various parts of body. Eosinophilia 26 LABORATORY DIAGNOSIS 27 SARCOCYSTIS IN MALAYSIA In Malaysia, 8 cases were reported in 70’s – majority from autopsy. During 2011-12, more than 100 european tourists visiting Pulau Tioman had muscular sarcocystosis (fever, myalgia/ myositis) In 2012, 89 students visiting Pulau Pangkor had muscular sarcocystosis (S. nesbitti from the snake) 28 TREATMENT & PREVENTION By avoiding eating raw or undercooked beef or pork. By avoidance of contamination of food and drink with feces of cat, dog, or other carnivorous animals. 29 THANK YOU 30