General Microbiology MCB 3020
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Exam 1 Nematodes Ascaris Ascariasis is a human disease caused by the parasitic roundworm Ascaris lumbricoides Perhaps as many as one quarter ofthe world39s people are infected and ascariasis is particularly prevalent in tropical regions and in areas of poor hygiene Other species of the genus Ascaris are parasitic and can cause disease in domestic animals Infection occurs through ingestion of food contaminated with fecal matter containing Ascaris eggs The larvae hatch burrow through the intestine reach the lungs and finally migrate up the respiratory tract From there they are then reswallowed and mature in the intestine growing up to 30 cm 12 in in length and anchoring themselves to the intestinal wall How is an Ascaris infection spread Ascaris eggs are found in human feces After feces contaminates the soil the eggs become infectious after a few weeks Infection occurs when a person accidentally ingests swallows infectious Ascaris eggs Once in the stomach immature worms hatch from the eggs The larvae are carried through the lungs and then to the throat where they are swallowed Once swallowed they reach the intestines and develop into adult worms Adult female worms lay eggs that are then passed in feces this cycle will take between 23 months Pigs can be infected with another species of Ascaris Occasionally a pig Ascaris infection can be spread to humans this occurs when infective eggs found in the soil and manure are ingested Infection is more likely if pig feces is used as fertilizer in the garden crops then become contaminated with Ascaris eggs How can I get ascariasis You or your children can become infected after touching your mouth with your hands that have become contaminated with eggs from soil or other contaminated surfaces or by ingesting contaminated food or water How is diagnosis of Ascaris made Your health care provider will ask you to provide stool samples for testing Some people notice infection when a worm is passed in their stool or is coughed up If this happens bring in the worm specimen to your health care provider for diagnosis There is no blood test used to diagnose an Ascaris infection What is the treatment for ascariasis Antiparasite antihelminthic medications are the first line of treatment against ascariasis The most common are mebendazole albendazole Albenza and pyrantel pamoate PinX These medications work by killing the adult worms Exam 1 You may have mild gastrointestinal side effects during treatment Each medication can be taken as a single dosen the United States Ascaris infections are generally treated for 13 days with medication prescribed by your health care provider The drugs are effective and appear to have few side effects Your health care provider will likely request additional stool exams 1 to 2 weeks after therapy if the infection is still present treatment will be repeated Infections are usually asymptomatic especially if the number of worms is small They may however be accompanied by inflammation fever and diarrhea and serious problems may develop if the worms migrate to other parts of the body What is an Ascaris infection Ascaris is a worm that lives in the small intestine Infection with Ascaris is called ascariasis asskuhryeuhsis Adult female worms can grow over 12 inches in length while the adult males are smaller How common is ascariasis Ascariasis is the most common human worm infection Infection occurs worldwide and is most common in tropical and subtropical areas where sanitation and hygiene are poor Children are infected more often than adults In the United States infection is rare but most common in rural areas of the southeast Skill CheCk I What are the signs and symptoms of an Ascaris infection Most people have no symptoms that are noticeable but infection may cause slower growth and slower weight gain If you are heavily infected you may have abdominal pain Sometimes while the immature worms migrate through the lungs you may cough and have difficulty breathing If you have a very heavy worm infection your intestines may become blocked I am pregnant and have just been diagnosed with ascariasis Can I be treated Infection with Ascaris worms is generally light and is not considered an emergency Unless your infection is heavy and your health may be at risk treatment is generally postponed until after delivery of the baby How can I prevent infection with Ascaris 1 Avoid contacting soil that may be contaminated with human feces 2 Do not defecate outdoors 3 Dispose of diapers properly 4 Wash hands with soap and water before handling food 5 When traveling to countries where sanitation and hygiene are poor avoid water or food that may be contaminated 6 Wash peel or cook all raw vegetables and fruits before eating Should I be concerned about spreading infection to the rest of my household No Infection is not spread from person to person Exam 1 Cycle Notes Adult worms Iolive in the lumen of the small intestine A female may produce approximately 200000 eggs per day which are passed with the feces Unfertilized eggs may be ingested but are not infective Fertile eggs embryonate and become infective after U on the 39 quot 39 18 days to several weeks 9 39 warm shaded soil 5km Check moist I A lnloctwu Siege A Diagnosis Stage A U nienilized egg wil no undergo A biological development Fertiled egg ll r IAI Ilulmumluiteth h no WM and odcoovldpdx Exam 1 After infective eggs are swallowed 0 the larvae hatch 9 invade the intestinal mucosa and are carried via the portal then systemic circulation to the lungs The larvae mature further in the lungs 10 to 14 days penetrate the alveolar walls ascend the bronchial tree to the throat and are swallowed Upon reaching the small intestine they develop into adult worms Between 2 and 3 months are required from ingestion of the infective eggs to oviposition by the adult female Adult worms can live 1 to 2 years Treatment Native Americans have traditionally used epazote Chenopodium ambrisioides for treatment which was not as powerful as 39 39 but passage of Ascarids provided some proof of efficacy Some recent studies exist in the medical literature suggesting that sundried papaya seeds may reduce infections by a large factor The adult dosage is one tablespoon of the seed powder in a glass of sugar water once a week for two weeks The sugar makes the bitter taste palatable and acts as a laxative Skill Check What is Epazote Epazote Wormseed Jesuit39s Tea Mexican Tea or Herba Sancti Mariee Chenopodium ambrosioides is a herb native to Central America South America and southern Mexico Its name derives from the Nahuatl word for quotskunk herbquot epatli skunk zotli herb It is an annual or shortlived perennial plant growing to 12 m tall irregularly branched with oblong lanceolate leaves up to 12 cm long The flowers are small and green produced in a branched panicle at the apex of the stem Exam 1 Trichinella Development The life cycle for this species begins after ingestion of the first stage juvenile from the intermediate host The worm molts four times within the first thirty hours and then mates These larvae exit through the gut wall and enter the blood system through the branches of the hepatic portal vein or through the lymphatic system They are transported all over the body and take up residence in voluntary muscles by entering individual muscle cells The larvae grow within the muscles and acoveringi J J h 39 After h 39 39 further The only way this species can continue its life cycle is to be ingested by another host through a predatorrprey interaction When the new host eatsthe muscle 39 i i g b y b 439 39 39 hr all A m the capsule and release the worm we u What is trichinellosis Also called trichinosis it is caused by eating 39739 raw or undercooked meat of animals infected with the larvae of a species of worm stage Infection Hr m quotl in LciLaiiI quot4 39 t 39 39 hilt m also occur in domestic pigs Vvhul ale quot 39 39 39 39 39 wau ea 39 diarrhea vomiting fatigue fe er J 39 439 1 39 trichinellosis Headaches fevers chills cough eye swelling achingjoints and muscle pains itchy skin diarrhea or constipation follow the rst symptoms If the infection is heavy patients may experience difficulty coordinating movements and have heart and breathing problems In severe cases death can occur For mild to moderate infections most symptoms subside within a few months Fatigue weakness and diarrhea may last for months Skill Chedlt l How soon after infection will symptoms appear Abdominal symptoms can occur 172 days after infection Further symptoms usually start 278 weeks after eating contaminated meat Symptoms may range from very mild to severe and relate to the number of infectious worms consumed in meat Often mild cases oftrichinellosis are never specifically diagnosed and are assumed to be the flu or other common illnesses How does infection occurin humans and animals When a human or animal eats meatthat contains infective Trichinella cysts the acid in the stomach dissolves the hard covering of the cyst and releasesthe worms The worms pass intothe small intestine and in 172 da s become mature After mating adult females lay eggs Eggs develop into immature worms travel through the arteries and are transported to muscles Within the musclesthe worms curl into a ballan inacapsule39 39 y in meat Reproduction The life cycle for this species begins after ingestion of the first stage juvenile from the intermediate host The worm molts four times within the first thirty hours and then mates Females may produce a pheromone to attract males The male coils around a female with his curved area overthe female genital pore The gubernaculums made of cuticle tissue guides spicules which extend through the cloaca and anus Males use spicules to hold the female during Exam 1 copulation Nematode sperm are amoeboidlike and lack flagella The female is ovoviviparous This means that she produces eggs but doesn39t lay them until they have already hatched in her uterus She lays her living larvae within the small intestine beginning the fifth or sixth day after infection Am I at risk for trichinellosis If you eat raw or undercooked meats particularly bear pork wild feline such as a cougar fox dog wolf horse seal or walrus you are at risk for trichinellosis Can I spread trichinellosis to others No Infection can only occur by eating raw or undercooked meat containing Trichinella worms What should I do if I think I have trichinellosis See your health care provider who can order tests and treat symptoms of trichinellosis infection If you have eaten raw or undercooked meat you should tell your health care provider How is trichinellosis infection diagnosed A blood test or muscle biopsy can show if you have trichinellosis How is trichinellosis infection treated Several safe and effective prescription drugs are available to treat trichinellosis Treatment should begin as soon as possible and the decision to treat is based upon symptoms exposure to raw or undercooked meat and laboratory test results How can I prevent trichinellosis 1 Cook meat products until the juices run clear or to an internal temperature of 170 o F 2 Freeze pork less than 6 inches thick for 20 days at 5 o F to kill any worms 3 Cook wild game meat thoroughly Freezing wild game meats unlike freezing pork products even for long periods of time may not effectively kill all worms 4 Cook all meat fed to pigs or other wild animals 5 Do not allow hogs to eat uncooked carcasses of other animals including rats which may be infected with trichinellosis 6 Clean meat grinders thoroughly if you prepare your own ground meats 7 Curing salting drying smoking or microwaving meat does not consistently kill infective worms Incubation time Abdominal symptoms can occur 1 2 days after infection Further symptoms usually start 2 8 weeks after eating contaminated meat Symptoms may range from very mild to severe and relate to the number of infectious worms consumed in meat and the amount of meat consumed Often mild cases of trichinosis are never specifically diagnosed and are assumed to be the flu or other common illnesses 9 TreatmentMuscle biopsy is used for trichinosis detection Several immunodiagnostic tests are also available Typically patients are treated with either Mebendazole or Albendazole but efficacy of such products are uncertain Symptoms can be relieved by use of analgesics and corticosteroids 9 Trichinellosis is acquired by ingesting meat containing cysts encysted larvae 00f Trichinella After exposure to gastric acid and pepsin the larvae are released efrom the cysts and invade the small bowel mucosa where they develop into adult worms 0female 22 mm in length males 12 mm life span in the small bowel 4 weeks After 1 week the females release larvae 0that migrate to the striated muscles where they encyst Trichinella pseudospiralis however does not encyst Encystment is cmpleted in 4 to 5 weeks and the encysted larvae may remain viable for several years l Skill Check Exam 1 frum utherammz s u Humans cuntzmmzted wwth such meat lngesliun ol 39quotgesmquot undercooked meal meal scmps esp pork or ammals Encyslud larva In slriawd muscle Lama veieased In small Jnlesllne Ba Encysled larva In slriated muscle A A6 at g Aduils in mm small unlasline o yawa deposited In mucosa Exam 1 The Whipworm The whipworm disease trichuriasis The parasitic roundworm infection of the large intestine often has no symptoms but a doctor usually can diagnose it by examining the stool and finding whip worm eggs Heavy infections may cause intermittent stomach pain bloody stools diarrhea and weight loss The name whipworm comes from the parasite s long very thin whip like shape Fertilized eggs develop outside the body and an embryonated egg is produced in three weeks in a favorable environment that is warm moist shaded soil Although the incidence of whipworm infection is high its intensity is usually light In the USA the infection occurs principally in warm moist climates most frequently among children People can get infected by accidentally eating whipworm eggs on their hands or in food or drink Severe infections in young children can result in serious disease with bloody diarrhea and a condition called rectal prolapsed Doctors treat whipworm disease most often with mebendazole and albendazole Exam 1 The Hook Worms The human hookworms include two nematode roundworm species Ancylostoma duodenale and Necator americanus Adult females 10 to 13 mm A duodenale 9 to 11 mm N americanus adult males 8 to 11 mm A duodenale 7 to 9 mm N americanus A smaller group of hookworms infecting animals can invade and parasitize humans A ceylanicum or can penetrate the human skin causing cutaneous larva migrans but do not develop any further A braziliense Uncinaria stenocephala l Skill chetk E Clinical Features Iron deficiency anemia caused by blood loss at the site of intestinal attachment of the adult worms is the most common symptom of hookworm infection and can be accompanied by cardiac complications Gastrointestinal and nutritionalmetabolic symptoms can also occur In addition local skin manifestations quotground itchquot can occur during penetration by the filariform larvae and respiratory symptoms can be observed during pulmonary migration of the larvae Treatment In countries where hookworm is common and reinfection is likely light quot infections are often not treated In the United States hookworm infections are generally treated with albendazoe Mebendazole or pyrante pamoate can also be used Hookworm can be treated with local cryotherapy when it is still in the skin Albendazole is effective both in the intestinal stage and during the stage the parasite is still migrating under the skin In case of anemia iron supplementation can cause relief symptoms of iron deficiency anemia However as red blood cell levels are restored shortage of other essentials such as folic acid or vitamin 312 may develop so this might also be supplemented Eggs are passed in the stool 0 and under favorable conditions moisture warmth shade larvae hatch in 1 to 2 days The released rhabditiform larvae grow in the feces andor the soil 399 and after 5 to 10 days and two molts they become become filariform thirdstage larvae that are infective These infective larvae can survive 3 to 4 weeks in favorable environmental conditions On contact with the human host the larvae penetrate the skin and are carried through the veins to the heart and then to the lungs They penetrate into the pulmonary alveoli ascend the bronchial tree to the pharynx and are swallowed The larvae reach the small intestine where they reside and mature into adults Adult worms live in the lumen of the small intestine where they attach to the intestinal wall with resultant blood loss by the host Most adult worms are eliminated in 1 to 2 years but longevity records can reach several years Skill check l Some A duodenale larvae following penetration of the host skin can become dormant in the intestine or muscle In addition infection by A duodenale may probably also occur by the oral and transmammary route N americanus however requires a transpulmonary migration phase Exam 1 A Infum m A own sw Exam 1 Trematodes Clonorchis Clonorchis sinensis is known as the oriental or Chinese liver fluke because it is distributed throughout Japan Korea China Taiwan and Vietnam view geographic distribution It is estimated that this species infects more than 30 million humans in these areas The parasite also infects a number of other animals including dogs cats pigs and rodents and these animals serve as reservoirs of infection The adult worms measure between 10 and 25 mm in length The do not actually live in the host39s liver but are found in the bile ducts inside of the liver Eggs are passed in the host39s feces and the first intermediate host is a snail Cercariae emerge from the first intermediate host and infect the second intermediate host The second intermediate host is a fish and over 100 species are susceptible to The worms can live at least 10 years infection The definitive host is infected when it eats raw or undercooked fish and possibly as long as 20 years The The metacercariae excyst in the host39s small intestine and the juvenile worm parasite causes thickening of the lining migrates up the common bile duct into the bile ducts inside of the liver of the bile duct and an inflammatory response in the surrounding liver tissue In heavy infections the bile duct epithelium can also be eroded and the parasite39s eggs will enter the liver tissue in such cases the eggs are surrounded by a fibrotic capsule Since the parasites can granuloma Heavy infections can also result in stenosis live for years and the narrowing or blockage of the bile ducts l Sklll Check number of paraSItes tends to increase as a person ages the damage to the liver and bile duct tends to accumulate over time and can result in death Exam 1 Fasciola The common name of this parasite the quotsheep liver flukequot is somewhat misleading since this parasite is found in animals other than sheep including cattle and humans and the parasite resides in the bile ducts inside the liver rather than the liver itself This species is a common parasite of sheep and cattle and therefore relatively easy to obtain Thus in introductory biology or zoology courses it is often used as quotTHEquot example of a digenetic trematode This species has been studied extensively by parasitologists and probably more is known about this species of digenetic trematode than any other The adult parasites reside in the intrahepatic bile ducts produce eggs and the eggs are passed in the host39s feces After passing through the first intermediate host a snail cercariae encyst on vegetation The definitive host is infected when it eats the 39 39 g 39 The 39 excysts in the definitive host39s small intestine and the immature worm penetrates the small intestine and migrates through the abdominal cavity to the host39s liver The juvenile worm penetrates and migrates through the host39s liver and finally ends up in the bile ducts view a diagram of the lifecycle The migration of the worms through the host39s liver and the presence of the worms in the bile ducts are responsible for the pathology associated with fascioliasis Fasciola hepatica is found in parts of the United States view distribution as well as in Great Britain Ireland Europe the Middle East the Far East Africa and Australia Fascioliasis in sheep and cattle results in animals that show low productivity low weight gain low milk production etc Also in many countries livers from animals infected with F hepatica are condemned as unsuitable for human consumption This not only results in a significant economic loss to ranchers and farmers but it also results in the loss of an important source of protein The infection can be diagnosed by finding eggs in the feces of animals but the eggs are difficult to differentiate from closely related species such as Fasciolopsis buski Several immunological methods for diagnosis are available Treatment The drug of choice in the treatment of fasciolosis is triclabendazole a member of the benzimidazole family of anthelmintics The drug works by preventing the polymerization of the molecule tubulin into the cytoskeletal structures microtubules However resistance of F hepatica to triclabendazole has already been recorded in Australial and reland2 Artemether has been shown to be effective in a rat model of fascioliasis Exam 1 Schistosoma Causal Agent of Schistosomiasis Schistosomiasis is caused by digenetic blood trematodes The three main species infecting humans are Schistosoma haematobium S japonicum and S mansoni Two other species more localized geographically are S mekongi and S intercalatum In addition other species of schistosomes which parasitize birds and mammals can cause cercarial dermatitis in humans Clinical Features Many infections are asymptomatic Acute schistosomiasis may occur weeks after the initial infection especially by S mansoni and S japonicum Manifestations include fever cough abdominal pain diarrhea hepato spenomegaly and eosinophilia Occasionally central nervous system lesions occur cerebral granulomatous disease may be caused by ectopic S japonicum eggs in the brain and granulomatous lesions around ectopic eggs in the spinal cord from S mansoni and S haematobium infections may result in a transverse myelitis with flaccid paraplegia Continuing infection may cause granulomatous reactions and fibrosis in the affected organs which may result in manifestations that include colonic polyposis with bloody diarrhea portal hypertension with hematemesis and splenomegaly cystitis and ureteritis with hematuria which can progress to bladder cancer pulmonary hypertension glomerulonephritis and central nervous system lesions Treatment Safe and effective drugs are available for the treatment of schistosomiasis Oxamniquine has been effective in treating infections caused by S mansoni in some areas in which praziquantel is less effective Schistosomiasis is readily treated using a single oral dose of the drug Praziquantel While it is safe and highly effective in curing an infected patient it does not prevent reinfection by cercariae and is thus not an optimum treatment for people living in endemic areas As with other major parasitic diseases there is ongoing and extensive research into developing a vaccine that will prevent the parasite from completing its life cycle in humans The following is Schistoma Life Cycle Immature eggs are discharged in the biliary ducts and in the stool Eggs become embryonated in water eggs release miracidia 9 which invade a suitable snail intermediate host 0 including many species of the genus Lymnae In the snail the parasites undergo several developmental stages sporocysts 539 rediae and cercariae The cercariae are released from the snail eand encyst as metacercariae on aquatic vegetation or other surfaces Mammals acquire the infection by eating vegetation containing metacercariae Humans can become infected by ingesting metacercariaecontaining freshwater plants especially watercress After ingestion the metacercariae excyst in the duodenum and migrate through the intestinal wall the peritoneal cavity and the liver parenchyma into the biliary ducts where they develop into adults In humans maturation from metacercariae into adult flukes takes approximately 3 to 4 months The adult flukes Fasciola hepatica up to 30 mm by 13 mm F gigantica up to 75 mm reside in the large biliary ducts of the mammalian host Fasciola hepatica infect various animal species mostly herbivores Exam 1 Schistosomiasis A meme save A mme 51 6 Guam Ilium a mall u mu m nauwmm samenu m mu 0 Lamw auxinNM F Ax quot7 Gamma lose mg mg 0 magnum m become PawnL quotM39m j mh amp we s a WWW i lnml llswe I lk A mm m wul we I d m hm m m k mmam o V v mum A mm a 9 E99 um releasmg mllmdla pm adunwuvms mmquot m bx Imp venulm unmmm v 4 zymg my man Mcume m m w m we V i m mm a n r Touch each number to reveal the information taking place at each step Exam 1 Cestodes TSoium T Solium has a very similar transmission pattern to T saginata Humans are the only known definitive hosts for the T solium Human infection begins with the ingestion of infected raw or under cooked pork The T Solium larvae gets digested out of the meat and attatches itsefto the upper small intestine region There it will mature and increase its number of proglottids Terminal gravid proglottids will break off from the main body and will either pass out with the stool or worm its way out of the anus In certain cases 3 or 4attatched proglotids will pass out together The eggs housed in the proglottids will be released and remain viable in the soil sewage and land for weeks However unlike T saginata both pigs and humans can become intermediate hosts to the T Solium When pigs and humans ingest the eggs the oncospheres will pierce through the intestinal walls travel through the circulatory system and plant itself in the subcutaneous and intramuscular tissues such as the brain and eyes Cysticercosis will develop in these areas and will become invective in 9 10 weeks Pigs will die in several months In humans cysticerosis has a variety of damaging effects on the central nervous system vision and brain functions TSaginata Is a long flattened ribbon like tapeworm that is white in color It is about 6 7milimeters in width The adult T Saginata ususually grows to be about 4 8 meters in length with about 1000 segments called proglottids Unlike the TSoium the scolex or mouth is quotunarmedquot because it has 4 suckers but no hooks As the tapeworm grows in the human intestine mature proglottis called gravid proglottids contain both male and female reproductive organs and houses 80 thousand eggs Each round egg measures 31 43 micrometers and contains an embryo an oncosphere As the tapeworm grows in the human intestine mature proglottis called gravid proglottid will be casted off out ofthe human body Each gavid proglottids contains both male and female reproductive organs and houses 80 thousand eggs Each round egg measures 31 43 micrometers and contains an embryo an oncosphere Humans are the only known definitive hosts for T saginata The life cycle begins Life cycle of Teenla saginata and Taenia solum Humans are the only de nitive hosts for Taena saghate and Taenlla solum Eggs or gravid proglottids are passed with feces 0 the eggs can survive for days to months in the environment Cattle 739 sagnatal and pigs 739 solum become infected by ingesting vegetation contaminated with eggs or gravid proglottids G In the animal39s intestine the oncospheres hatch 9 invade the intestinal wall and migrate to the striated Exam 1 muscles where they develop into cysticerci A cysticercus can survive for several years in the animal Humans become infected by ingesting raw or undercooked infected meat 0 In the human intestine the cysticercus develops over 2 months into an adult tapeworm which can survive for years The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine 0 Length of adult worms is usually 5 m or less for 739 saghate however it may reach up to 25 m and 2 to 7 m for 739 solum The adults produce proglottids which mature become gravid detach from the tapeworm and migrate to the anus or are passed in the stool approximately 6 per day 739 saghate adults usually have 1000 to 2000 proglottids while 739 solum adults have an average of 1 000 proglottids The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces 739 saghate may produce up to 100000 and 739 solum may produce 50000 eggs per proglottid respectively Ex aml The cestodes tapeworms Taenia saginata beef tapeworm AWNquot mm mm 01 qu mulch mm mm m mqum a coma Imam meat WWW m m n msmx hm m lanes 0 h came it Ingmnl mm w r hum Baum wens hy Mammy 9mm mmmm n was a 9mm magma A mum Sinus A magma smw Eggs a 9mm mthde m fete m puea Wu mmnml Touch the numbers tn reveal Information for each of the steps Exam 1 Protozoa Protozoa are singlecelled organisms that behave like tiny animals hunting and gathering other microbes for food Protozoa can live within your body as a parasite Many protozoa inhabit your intestinal tract and are harmless Others cause disease such as the 1993 Cryptosporidium panum invasion of the Milwaukee water supply 39 U more than 400000 people Often these organisms spend part of their life cycle outside of humans or other hosts living in food soil water or insects Most protozoa are microscopic but there are some exceptions One type of oceandwelling protozoa foraminifer can grow to more than 2 inches in diameter Some protozoa invade your body through the food you eat or the water you drink Others can be transmitted through sexual contact Still others are vectorborne meaning they rely on another organism to transmit them from person to person Malaria is an example of a disease caused by a vectorborne protozoan parasite Mosquitoes are the vector transmitting the deadly parasite plasmodium which causes the disease Protozoan informal term for the unicellular heterotrophs of the kingdom Protista Protozoans comprise a large diverse assortment of microscopic or nearmicroscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues Formerly classi ed in the animal kingdom they are now generally divided into four protist phyla Mastigophora the agellates Sarcodina the amebas Ciliophora the ciliates and Sporozoa Most are motile and most ingest food as do animals rather than produce it themselves as do plants The 26000 living species are cosmopolitan in distribution they are found in freshwater and at all depths in the ocean some live in soil Some are parasites in the bodies of humans or other animals sometimes causing diseases Exam 1 Sarcodines Ameobiasis Who are at risk for ameobiasis Although anyone can have the disease it is most common in people who live in developing countries that have poor sanitary conditions In the united states ameobiasis is most often found in immigrants from developing countries It also is found in people who have traveled to developing countries and in people who live in institutions that have poor sanitary conditions Men who have sex with other men can become infected and can get sick from the infection but they often do not have symptoms Ameobiasis is transmitted by fecal contamination of drinking water and foods but also by direct contact with dirty hands or objects as well as by sexual intercourse How can I become infected with E hystolytica By putting anything into your mouth that has touched the stool of a person who is infected with E hystolytica By swallowing something such as water or food that is contaminated with E hystolytica By touching and bringing to your mouth cysts eggs picked from surfaces that are contaminated with E histolytica What are the symptoms of ameobiasis On average about one in ten people who are infected with E histolytica becomes sick from the infection The symptoms often are quite mild and can include loose stools stomach pain and stomach cramping Amebic dysentery is a severe form ofameobiasis associated with stomach pain bloody stools and fever Rarely E histolytica invades the liver and forms an abscess Even less commonly it spreads to other parts of the body such as the lungs or brain To the leftis the trophozoite stage How is ameobiasis diagnosed Your health care provider will ask you to submit stool samples Because E histolytica is not always found in every stool sample you may be asked to submit several stool samples from several different days Diagnosis of ameobiasis can be very difficult One problem is that other parasites and celles can look very similar to E histolytica when seen under a microscope Therefore sometimes people are told that they are infected with E histolytica even though they are not Entamoeba histolytica and another amoeba Entamoeba dispar which is about ten times more common look the same when seen under a microscope Unlike infection with E histolytica which sometimes makes people sick infection with E dispar never makes people sick and therefore does not need to be treated If you have been told that you are infected with E histolytica but are feeling fine you might be infected with E dispar instead Unfortunately most laboratories do not yet have the test that can tell whether a person is infected with E histolytica or with E dispar Until these tsts become more widely available it usually is best to assume that the parasite is E histolytica A blood test is also available However the test is recommended only when your health care provider thinks that your infection has invaded the wall of the intestine gut or some other organ of your body such as the liver Exam 1 rhsr rst one and then the other wfyour hreouoh has made you sroh x h A h uvl flU mmmen mmouool V k x r v N a h 5 Exty u vrhu rrrx 0Wquot quotfdw Ihm hthoblnodnmam Wining mes sud as N Twhmmm mam WM W w V Ymuhozmusmrglam lo the huge mmune r Vvophnzmms mmde 39u 39 xhzmmshnalmumsa g m r A x r Immaunecyu marrowmmournV r uyhmmy mun w Encymuen Next 0am ohor h h m 0 9 oohomohs through the vemsmthe heart and then tome mhgs 39 0 The arvae where thev auaoh tome mtestma waH wnh resoham b ood oss or the host 9 Most aooh worms are ehmmated h 1 to z veers but ohgevrw records can reach severa veers A l Exam 1 addition infection by A duodenale may probably also occur by the oral and transmammary route N americanus however requires a transpulmonary migration phase Exam 1 AA A Imam shun A Mm Slag 0 mm m um A A n momma Wanna um unm Dunn 4 Emmqu mm gnmmmA Touch the this step Exam 1 Naegleria Is an ameba commonly found in the environment in water and soil Only one species of Naegleria has been found to infect humans Naegleria fowleri This organism is found in 1 Warm bodies of fresh water such as lakes rivers and hot springs 2 Warm water discharge form industrial plants 3 Under chlorinated swimming pools 4 Soil Infection with Naegleria is most common during the dry summer months when the temperature is above 80 degrees F and the water is warm and water levels are low Infection with Naegleria causes the disease primary amebic meningoencephalitis PAM a brain inflammation which leads to the destruction of brain tissue Initial signs and symptoms of PAM include headache fever nausea vomiting and stiff neck As the ameba causes more extensive destruction of brain tissue this leads to confusion lack ofattention to people and surroundings loss of balance and bodily control seizures hallucinations The disease progresses rapidly and infection usually results in death within 3 to 7 days Is there treatement for infection with Naegleria Several drugs are effective against Naegleria in the laboratory However although a variety of treatments have been used to treat infected persons their effectiveness is unclear since most infections have still been fatal Prompt diganosis and treatment may help How can I prevent an infection with Naegleria 1 Avoid swimming orjumping into bodies of warm fresh water 8 Avoid swimmming in thermally polluted water water around power plants 3 Do not swim in areas posted as no swimming 5 Hold the nose shut or use nose clips when jumping or diving into bodies of fresh water Exam 1 Ciliates Balantidiasis Cysts are the parasite stage responsible for transmission of balantidiasis The host most often acquires the cyst through ingestion of contaminated food or water Following ingestion excystation occurs in the small intestine and the trophozoites reside in the lumen of the large intestine of humans and animals where they replicate by binary fission during which conjugation may occur Trophozoites undergo encystations to produce infective cysts Some trophozoites invade the wall of the colon and multiply Some return to lumen and disintegrate Mature cysts are passed with feces Because pigs are an animal reservoir human infections occur more frequently in areas where pigs are raised Other potential animal reservoirs include rodents and nonhuman primates Clinical Features Most cases are asymptomatic Clinical manifestations when present include persistent diarrhea occasionally dysentery abdominal pain and weight loss Symptoms can be severe in debilitated persons Laboratory Diagnosis Diagnosis is based on detection of trophozoites in stool specimens or in tissue collected during endoscopy Cysts are less frequently encountered Balantidium coli is passed intermittently and once outside the colon is rapidly destroyed Thus stool specimens should be collected repeatedly and immediately examined or preserved to enhance detection of the parasite Treatment The drug choise is quot with39 39 I 39 39 and quot 39 as 39 39 T quot are in pregnancy and in children less than 8 years old Exam 1 Flagellates Trypansoma An infected triatomine insect vector or quotkissingquot bug takes a blood meal and releases trypomastigotes posterior of nucleus connected by a long undulating membrane in its feces near the site of the bite wound Trypomastigotes enter the host through the wound or through intact mucosal membranes such as the conjunctiva Common triatomine aka kissing bugs vector species for trypanosomiasis belong to the genera Triatoma Rhodinius and Panstrongylus Inside the host the trypomastigotes invade cells where they differentiate into intracellular amastigotes reduced or absent The amastigotes multiply by binary fission and differentiate into trypomastigotes and then are released into the circulation as bloodstream trypomastigotes Trypomastigotes infect cells from a variety of tissues and transform into intracellular amastigotes in new infection sites Clinical manifestations can result from this infective cycle The bloodstream trypomastigotes do not replicate different from the African trypanosomes Sleeping sickness is a parasitic disease in people and in animals Caused by protozoa of genus Trypanosoma and transmitted by the tsetse fly Replication resumes only when the parasites enter another cell or are ingested by another vector The quotkissingquot bug becomes infected by feeding on human or animal blood that contains circulating parasites The ingested trypomastigotes transform into epimastigotes anterior of nucleus connected by a long undulating membrane in the vector39s midgut The parasites multiply and differentiate in the midgut and differentiate into infective metacyclic trypomastigotes in the hindgut Trypanosoma cruzi also called American trypanosomiasis can also be transmitted through blood transfusions organ transplantation transplacentally and in laboratory accidents Exam 1 li 9 During a blood meal on the mammalian host an infected tsetse y genus Gloss7a injects metacyclic trypomastigotes into skin tissue The parasites enter the lymphatic system and pass into the bloodstream 0 Inside the host they transform into bloodstream trypomastigotes 9 are carried to other sites throughout the body reach other blood uids eg lymph spinal fluid and continue the replication by binary fission 9 The entire life cycle of African Trypanosomes is represented by extracellular stages The tsetse fly becomes infected with bloodstream trypomastigotes when taking a blood meal on an infected mammalian host 390 9 In the fly s midgut the parasites transform into procyclic trypomastigotes multiply by binary ssion 39939 leave the midgut and transform into epimastigotes 0 The epimastigotes reach the fly s salivary glands and continue multiplication by binary fission 9 The cycle in the fly takes approximately 3 weeks Humans are the main reservoir for Trypanosoma brucei and Tgambense but this species can also be found in animals Wild game animals are the main reservoir of 739 braceand rhodesense Exam 1 mm ny Sum Humn sunc wmm W hen a a um an m M 39 M Iunllm mx 39 hymnawn f O m A M m 39 mamum o m mum lrywmlshw u m m uum m m m mm Imamum m u m w quotmm mm mm alum Mn WynMN ummm I me 1mm mm my new 9 A l 0mm m m IVW r x mm W In Place the mouse ovar mu number m rmmnm m gummy mm Sm D nunam snu Exam 1 G39 rdia Causal Agent Giardia intestinalis is a protozoan flagellate Diplomonadida This protozoan was initially named Cerecomonas intestinalis by Laml in 1859 and renamed Giardia lamblia by Stiles in 1915 in honor of Professor Giard of Paris and Dr F Lambl of Prague However many consider the name Giardia intestinalis to be the correct name for this protozoan Cysts are resistant forms are responsible for transmission of giardiasis Both cysts and trophozoites can be found in feces diagnostic stages The cysts are hardy can survive several months in cold water Infection occurs by the ingestion of cysts in contaminated water food or by the fecal oral rout hands or fomites In the small intestine excystation releases trophozoites each cyst produces 2 trophozoites Trophozoites multiply by longitudinal binaw fission remaining in the lumen ofthe proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk Encystation occurs as the parasites transit toward the colon The cyst is the stage found most commonly in non diarrheal feces Because the cysts are infectious when passed in the stool or shortly afterward person to person transmission is possible While animals are infected with Giardia their importance as a resenoir is unclear Giardia Exam 1 Trichomonas What is Trichomonas It is a common sexually transmitted disease STD that affects both women and men although symptoms are more common in women Trichomoniasis is the most common curable STD in young sexually active women An estimated 74 milion new cases occur each year in women and men Trichomonas vaginalis an anaerobic parasitic flagellated protozona is the causative agent of trichomoniasis and is the most common pathogenic protozoan infection of humans in industrialized countries The WHO has estimated that 180 million infections are acquired annually worldwide The estimated for North America alone are between 5 and 8 milion new infections each year with an estimated rate of asymptomatic cases as high as 50 Trichomonoiasis can occur in females males rarely exhibit any symptoms of a T Vaginalis infection if the normal acidity of the vagina is shifted from healthy semiacidic pH 3842 to a much more basic one 56 that is conducive to T vaginalis growth Some of the symptoms ofT vaginalis include preterm delivery low birth weight and increased mortality as well as predisposing to HIV infection AIDS and cervical cancer Trichomonas vaginalis is a microscopic parasite found worldwide Infection with Trichomonas is called trichomoniasis Trichomoniasis is one of the most common sexually transmitted diseases mainly affecting sexually active women In North America it is estimated that more than 8 million new cases are reported yearly How is trichomonoiasis spread It is spread through sexual activity Infection is more common in women who have had multiple sexual partners A common misbelieve is that infection can be spread by a toilet seat this isn t likely since the parasite cannot live long in the environment or on objects What are the signs and symptoms of infection Most men with this infection do not have symptoms When symptoms are present they are most commonly are discharged from the urethra the urge to urinate and a burning sensation with urination What are the signs and symptoms of infection I In women Signs and symptoms of infection range from having no I 39 to very Typical symptoms include foul smelling or frothy green discharge from the vagina vaginal itching or redness Other symptoms can include painful sexual intercourse lower abdominal discomfort and the urge to urinate How long after infection do symptoms occur The normal incubation period is 428 days The onset of symptoms such as vaginal or vuvlal pruritus and discharge is often sudden and occurs during or after menstruation as a result of the increased vaginal acidity I have trichomonisasis and am pregnant can I spread infection to my baby Yes but this is rare Babies born to infected mothers may contract infection during delivery Infants may develop fever girls may develop vaginal discharge Children should be treated if diagnosed See your health care provider about treatment of trichomoniasis during pregnancy Exam 1 Sporozoan Malaria What is malaria It is a serious and sometimes fatal disease caused by a parasite Patients with malaria typically are very sick with high fevers shaking chills and flulike illness Four kinds of malaria parasites can infect humans Plasmodium falciparum P vivax P ovale and P malariae Infection with any of the malaria species can make a person fell very ill infection with P falciparum if not promptly treated may be fatal Although malaria can be a fatal disease illness and death from malaria are largely preventable s malaria a common disease The World Health Organization estimates that each year 300500 million cases of malaria occur and that more than 1 million people die of malaria About 1200 cases of malaria diagnosed in the United States each year The vast majority of cases in the USA are in travelers and immigrants returning from malariarisk areas many from subSaharan Africa and Indian subcontinent s malaria a serious disease Malaria is leading cause of death and disease worldwide especially in developing countries Most deaths occur in young children For example in Africa a child dies from malaria every 30 seconds Because malaria causes so much illness and death the disease is a great drain on many national economies Since many countries with malaria are already among the poorer nations the disease maintains a vicious cycle of disease and poverty How is malaria transmitted Usually people get malaria by being bitten by an infected female Anopheles mosquito Only Anopheles mosquitoes can transmit malaria and they must have been infected by a previous blood meal taken on an infected person When a mosquito bites a small amount of blood is taken in which contains the microscopic malaria parasites The parasite grows and matures in the mosquito s gut for a week or more then travels to the mosquito s salivary glands When the mosquito next takes a blood meal the parasites mix the saliva and are injected into the bite Once in the blood the parasites travel to the liver and enter liver cells to grow and multiply During this incubation period the infected person has no symptoms After as few as 8 days or as long as several months the parasites leave the liver cells and enter red blood cells Once in the cells they continue to grow and multiply After they mature the infected red blood cells rupture freeing the parasites to attack and enter other red blood cells Toxins released when the red cells burs are what cause the typical fever chills and flulike malaria symptoms If a mosquito bites the infected person and ingests certain types of malaria parasites quotgametocytesquot the cycle of transmission continues Because the malaria parasite is found in red blood cells malaria can also be transmitted through blood transfusion organ transplant or the shared use of needles or syringes contaminated with blood Malaria may also be transmitted from a mother to her fetus before or during delivery congenital malaria Malaria is not transmitted from person to person like a cold or the flu You cannot get malaria from casual contact with malaria infected people Who are the people most at risk of severe and fatal malaria Exam 1 Plasmodium falciparum causes severe and life threatening malaria this parasite is very common in many countries in Africa south of the Sahara People who are heavily exposed to the bites of the mosquitos infected with P falciparum are most at risk of dying from malaria People who have little or no immunity to malaria such as young children and pregnant women or travelers coming from areas with no malaria are more likely to become severely ill and die Poor people living in rural areas who lack knowledge money or access to health care are more vulnerable to the disease As a result of all these factors an estimated 90 of deaths due to malaria occur in Africa south of the Sahara most of these deaths occur in children under 5 years of age Isn t there a malaria vaccine And if not why There is currently no malaria vaccine approved or human use The malaria parasite is a complex organism with a complicated life cycle ts antigens are constantly changing and developing a vaccine against these varying antigens is very difficult In addition scientists do not yet totally understand the complex immune responses that protect humans against malaria However many scientists all over the world are working on developing an effective vaccine Because other methods of fighting malaria including drugs insecticides and bed nets have not succeeded in eliminating the disease the search for a vaccine is considered to be one of the most important research projects in public health i 2 9 The malaria parasite life cycle involves two hosts During a blood meal a malariainfected female Anopheles mosquito inoculates sporozoites into the human host Sporozoites infect liver cells eand mature into schizonts 9 which rupture and release merozoites Of note in P Vivax and P ovale a dormant stage hypnozoites can persist in the liver and cause relapses by invading the bloodstream weeks or even years later After this initial replication in the liver exoerythrocytic schizogony El the parasites undergo asexual multiplication in the erythrocytes erythrocytic schizogony B Merozoites infect red blood cells 9 The ring stage trophozoites mature into schizonts which rupture releasing merozoites Some parasites differentiate into sexual erythrocytic stages gametocytes Blood stage parasites are responsible for the clinical manifestations of the disease Exam 1 Life Stages I 39 39 quot a fun a life cycle egg larva pupa and adult The rst three stages are M NA A 1 vcuuu do not live more than 1 2 weeks in nature although hatching may take up to 23 weeks in L colder climates 0 77 i Mosquito larvae have a welldeveloped head with mouth brushes used for feeding a large thorax and a segmented abdomen They have no legs In contrast to other mosquitoes Anopheles larvae lack a respiratory siphon and for this reason position themselves so that their body is parallel to the surface of the water a Exam 1 Larvae breathe through spiracles located on the Bth abdominal segment and therefore must come to the surface frequently The larvae spend most of th r time 39 algae bacteria and other microorganisms in the 39 b surface only when disturbed L ae swim ether 39erky movements of the entire body or through propulsion with the mouth brushes Larvae develop through 4 stages or instars after which they metamorphose into pupae At the end of each instar the larvae molt shedding their exoskeleton or skin to allow for further rowth m g I 39 a illllucuhcu by 39 Mosouitoes can develop from egg to adult in as little as 5 days but usually take 1014 days in tropical conditions Mosquito39s Life Cycle 6 nun mm Exam 1 Toxoglasma Members ofthe cat family Felidae are the only known de nitive hosts for the sexual stages of T gundii and thus are the main reservoirs ofinfection Cats become infected with T gundii by carnivorism After tissue cysts or oocysts are ingested by the cat viable organisms are released and invade epithelial cells ofthe small intestine where they undergo an asexual followed by a sexual cycle and then form oocysts which are excreted The unsporulated oocyst takes 1 to 5 days after excretion to sporulate become infective Although cats shed oocysts for only 1 to 2 weeks large numbers may be shed Oocysts can survive in the environment for several months and are remarkably resistant to disinfectants freezing and drying but are killedby heating to 70 C for 10 minutesHuman infection may be acquired in several ways A meme Slaae A magnum Sage 0 Hum oocysts and Sue cysxs ranslarm snunw aner ingasIon man Dames infected Iacnyzones can We me lems via me mandsueam A ingestion of undercooked infected meat containing Tuxuplasma cysts B ingestion ofthe oocyst from fecally contaminated hands or food C organ 39 or blood 39 D transmission E accidental inoculation of tachyzoites The parasites form tissue cysts most commonly in skeletal muscle myocardium and brain these cysts may remain throughout the life of the host
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