Parasitic Diseases Flashcards
1
Q
Epidemiology of parasitic diseases?
A
- majority occur in tropical regions, where there is poverty, poor sanitation and personal hygiene
- often entire communities may be infected with multiple, different organisms which remain untx b/c tx isn’t accessible
2
Q
Epidemiology of parasitic diseases?
A
- majority occur in tropical regions, where there is poverty, poor sanitation and personal hygiene
- often entire communities may be infected with multiple, different organisms which remain untx b/c tx isn’t accessible
3
Q
What does effective prevention and control of parasitic diseases require?
A
- “mass intervention strategies” and intense community education. Examples include:
- general improved sanitation: pit latrines, fresh water wells, piped water
- vector control: insecticide impregnated bed nets, spraying of houses with residual insecticides, drainage, and landfill
- mass screening and drug administration programs which may need to be repeated at regular intervals
4
Q
What are parasites?
A
- organisms that infect and cause disease in other animals: protozoa, helminths, and arthropods
5
Q
How are protozoa transmitted?
A
- can be passed directly from host -> host through sexual contact, by contaminated water, or through arthropod vector.
- Direct or indirect transmission results from ingestion of highly resistant spores that are shed in feces of infected host
- most are mobile by means of flagella, cilia or ameboid motion
6
Q
How are helminths transmitted?
A
- wormlike parasites
- transmission occurs primarily through ingestion of fertilized eggs or the penetration of the infectious larval stages through the skin
- infections can involve many organs: liver, lungs, urinary and intestinal tract, circulatory, and nervous systems, and muscles
3 main groups: - flatworms (platyhelminths)
- thorny-headed worms (acanthocephalins)
- roundworms (nematodes)
7
Q
What are the most common arthropods?
A
flies, fleas, ticks, mosquitoes, and lice
- transmission from arthropod to human occurs either mechanically or biologically
8
Q
Effects of parasitic infections?
A
- typically, a parasitic infection doesn’t directly kill a host
- the stress placed on the host’s resources can affect its growth, ability to reproduce and survival
- This stress can sometimes lead to host’s premature death
9
Q
Pathogenesis of parasitic infection?
A
- organisms attack a host and begin to multiply
- multiplies and increasingly interferes with the normal life functions of the host
- Host begins to feel ill as a sx of parasite’s invasion and activities
- In many cases, the host’s immune system may be able to respond to the parasite and destroy it (immunocompetent person)
10
Q
What is unique about parasites?
A
- complex life cycles
- may spend part of their life cycle in a variety of differential species hosts
- Host species may be animal (all types), insect, or other
- May live only in water, or on veggies (grass, and soil)
11
Q
What does effective prevention and control of parasitic diseases require?
A
- “mass intervention strategies” and intense community education. Examples include:
- general improved sanitation: pit latrines, fresh water wells, piped water
- vector control: insecticide impregnated bed nets, spraying of houses with residual insecticides, drainage, and landfill
- mass screening and drug administration programs which may need to be repeated at regular intervals
12
Q
What are parasites?
A
- organisms that infect and cause disease in other animals: protozoa, helminths, and arthropods
13
Q
How are protozoa transmitted?
A
- can be passed directly from host -> host through sexual contact, by contaminated water, or through arthropod vector.
- Direct or indirect transmission results from ingestion of highly resistant spores that are shed in feces of infected host
- most are mobile by means of flagella, cilia or ameboid motion
14
Q
How are helminths transmitted?
A
- wormlike parasites
- transmission occurs primarily through ingestion of fertilized eggs or the penetration of the infectious larval stages through the skin
- infections can involve many organs: liver, lungs, urinary and intestinal tract, circulatory, and nervous systems, and muscles
3 main groups: - flatworms (platyhelminths)
- thorny-headed worms (acanthocephalins)
- roundworms (nematodes)
15
Q
What are the most common arthropods?
A
flies, fleas, ticks, mosquitoes, and lice
- transmission from arthropod to human occurs either mechanically or biologically
16
Q
Effects of parasitic infections?
A
- typically, a parasitic infection doesn’t directly kill a host
- the stress placed on the host’s resources can affect its growth, ability to reproduce and survival
- This stress can sometimes lead to host’s premature death
17
Q
Pathogenesis of parasitic infection?
A
- organisms attack a host and begin to multiply
- multiplies and increasingly interferes with the normal life functions of the host
- Host begins to feel ill as a sx of parasite’s invasion and activities
- In many cases, the host’s immune system may be able to respond to the parasite and destroy it (immunocompetent person)
18
Q
What is unique about parasites?
A
- complex life cycles
- may spend part of their life cycle in a variety of differential species hosts
- Host species may be animal (all types), insect, or other
- May live only in water, or on veggies (grass, and soil)
19
Q
Protozoa species?
A
- Sarcodina (amebas)
- Sporozoa ( non- motile sporozoans)
- Mastigophora (flagellates)
- Ciliata (ciliates)
20
Q
Metazoa (helminth) species?
A
- flatworms (platyhelminthes): flukes (Trematoda), and tapeworms (Cestoda)
- roundworms (nemathelminthes)
21
Q
What are protozoa and what kind of disease state do they cause?
A
- single cell (unicellular) organisms
- historically been the cause of more disease and death than any other category of disease-causing organisms:
- Malaria
- African sleeping sickness
22
Q
What is a trophozoite?
A
- term for the live adult protozoa
- cysts, spore or “eggs” are non-adult forms
- Most of these diseases are spread by the fecal-oral route
23
Q
What is the cause of Giardiasis?
A
- Giardia lamblia, a flagellate, is a common pathogenic protozoan
- infects duodenum and jejunum of humans
24
Q
Epidemiology of Giardiasis?
A
- occurs worldwide
- humans are infected by ingestion of fecally contaminated water or food containing giardia cysts
- it is also spread by direct person-person contact, which has caused outbreaks in institutions such as day care centers
- Oral-fecal transmission
At high risk: infants, kids
->especially internationally adopted kids
25
How long can Giardia lambda cysts survive in water?
| How are humans infected?
up to 3 months
- outbreaks among campers in wilderness areas suggest that humans may be infected with guard harbored by rodents, deer, cattle, sheep, horses, or household pets
- life cycle: 2 forms: cysts: infectious form, and trophozoites: mature form
- localize to the small bowel, adhere and once they get back into cyst form -> go into stool
26
What will a biopsy of small bowel show?
- parasites attach to the bowel wall and may cause irritation and low-grade inflammation of duodenal or jejunal mucosa so a bx of the small bowel will show:
- crypt hypertrophy
- villous atrophy or flattening
- epithelial cell damage
27
Sx forms of giardiasis?
- a large portion of infected pts are asymptomatic but sx forms are:
1. acute diarrhea
2. chronic diarrhea
3. malabsorption syndrome
28
Presenting sxs of Giardiasis?
- presenting sxs can be diarrhea, malaise, steatorrhea, abdominal cramps, bloating, flatulence, N/V, and wt loss
- pts with chronic infection often experience major wt loss, malabsorption and depression
- the stools may be watery, semisolid, greasy, bulky, and foul-smelling at various times during the course of the infection
29
Giardiasis encystment?
- as the parasites pass into the colon they typically encyst
- cysts are found in the stool
- > often in enormous numbers
30
Work up of Giardiasis?
- stool sample-fecal smear: this is to look for ova and parasites, The dx depends upon finding the distinctive cysts in formed stools, or cysts or the protozoa in liquid stools. A series of 3 or more stool exams on alt. days is therefore recommended
- stool enzyme-linked immunosorbent assay (ELISA) has been shown to be both a specific and sensitive rapid dx tool
- Exam of duodenal contents: may be necessary to establish the dx, as cyst production may be sporadic and not found in the stool by an ovum and parasite fecal smear examination
31
Giardiasis tx?
metronidazole (Flagyl): 250 mg 2x daily for 5 days will clear over 90% of Giardia lamblia infections (can become lactose intolerant while having giardiasis -> this will go away after 1 week of tx)
- oral tinidazole and nitazoxinide are alternatives
32
Prevention of giardiasis?
- avoid contaminated water sources
- hikers or campers should boil water or use iodine or filtration with a large pore sized filter
- adequate disposal of diapers and frequent hand washing for daycare centers
33
What causes cryptosporidiosis?
- a coccidian protozoan parasite (Cryptosporidium hominis)
- associated with contaminated water supplies
- unknown as human pathogen prior to 1976
- one of the most common causes of waterborne illness in the US
34
Where do the cryptosporidium localize to?
- the intracellular spheres are found in great numbers just under the outer membrane of the cells lining the stomach or intestine
- oocysts, passed into feces in enormous numbers, are the infective agents
- get into digestive tract but also can get into resp. tract
35
Site of cryptosporidium infection?
- epithelial cells of GI tract
- Has affected other tissues such as respiratory tract tissues and conjunctiva of the eye
- infectious dose
36
Sxs of Cryptosporidium?
- some individuals can be asymptomatic
- incubation period: 7-10 days (range 3-28)
- sxs include:
stomach cramps, pain, watery diarrhea, dehydration, vomiting, and fever
severe sxs: profuse, watery diarrhea, severe malabsorption, electrolyte imbalance and marked wt loss
37
Dx of Cryptosporidium?
- usually made by examining stool specimens. 3 stools may be required. Microscopy with an acid fast stained stool smear is usually dx (acid fast stain****)
- enzyme immunoassay for greatest sensitivity and specificity or molecular methods using PCR
38
What is usually dx test for cryptosporidium?
- acid fast stain on stool
39
Tx of Cryptosporidium?
- Nitazonxanide: can be used for pediatric patients
adults: 500 mg q 12 hours
children (1-3): 100 mg q 12 hours
children (4-11): 200 mg q 12 hours
40
Prevention of cryptosporidium?
- water purification and filtration (resistant to chlorine)
- routine testing:
use of 1 micron filter to remove cysts
boil water
the sporocysts are resistant to most chemical disinfectants, but are susceptible to drying and the UV portion of sunlight
- drink bottled water when traveling abroad
- wash hands frequently
- this protozoan is susceptible to freezing
- want person to avoid swimming pools after infection has resolved -> can infect pool water
41
What is the common parasite found in large intestine of humans?
Entamoeba histolytica is common parasite in large intestine of travelers
- mostly a disease of travelers
42
What are the 3 stages of intestinal amebiasis?
- the active amoeba
- the inactive cyst
- the intermediate precyst
43
What are the 2 strains that cause intestinal amebiasis?
- Entamoeba histolytica
| - Dientamoeba fragilis
44
Pathogenesis of Entamoeba histolytica?
- fecal-oral transmission
- cyst is ingested: the trophozoite emerges from the ingested cyst in the stomach and duodenum.
- Each of which divides again to produce 8 small trophozoites per infective cyst
- these pass to the cecum and produce a population of lumen-dwelling trophozoites
- *** disease results when trophozoites of Entamoeba histolytic invade the intestinal epithelium
- mucosal invasion with the aid of the proteolytic enzymes occurs through the bowel wall
- causes discrete ulcers with a pinhead-sized center and raised edges, from which mucus, necrotic cells, and amoebas pass
- Subsequent spread may coalesce colonies of amoebas, undermining large areas of mucosal surface
- trophozoites may penetrate the muscular coats and occasionally the serosa, leading to perforation into the peritoneal cavity
- secondary bacterial invasion, and accumulation of neutrophilic leukocytes can occur.
45
Extraintestinal infection of Entamoeba histolytic amebiasis is what?
- metastatic, amoebas spread through the blood
- rarely occurs by direct extension from the bowel
- By far the most common form is amoebic hepatitis, or liver abscess (4% or more common of clinical infections): this is assumed to be due to micro emboli including trophozoites carried through portal circulation.
46
What factors determine the invasion of amoebas in Entamoeba histolytica amebiasis?
- number of amoebas ingested
- pathogenic capacity of the parasite strain
- host factors such as gut motility and immune competence
47
Clinical findings of amebiasis?
- sxs vary greatly depending upon the site and intensity of lesions:
- extreme abdominal tenderness
- fulminating dysentery and dehydration occur in serious disease
- in less acute disease, onset of sxs is usually gradual: episodic diarrhea, abdominal cramps, N/V, and urgent desire to defecate (takes 1-3 weeks)
- more frequently there will be weeks of cramps and general discomfort, loss of appetite, wt loss, and malaise
48
Lab test for Amebiasis?
- stool specimens:
fluid feces: fresh and warm for immediate exam of trophozoites. After a saline purge for cysts and trophozoites
- formed feces for cysts
- serology is available (EIA -> enzyme immunoassay)
49
Tx of Amebiasis?
- E. histolytica should be differentiated from morphologically similar species and tx appropriately.
- Given small but substantial risk of invasive disease and the potential to transmit the infection to others, WHO recommends tx all cases of proven E. histolytica regardless of sxs
- Asymptomatic intestinal infection: Paromomycin 10 days of 30 mg/Kg divided into 3 doses and diloxanide furoate 500 mg tid x 10 days
- symptomatic: paromomycin as above after metronidazole (flagyl) 750 mg, 3x a day, for 5-10 days, tx should be followed by administration of diolxanide to eradicate any potential intestinal reservoirs
- w/ early tx prognosis is good
50
Prevention of amebiasis?
- avoid contaminated food and water
- wash and cook veggies
- hand washing
- chemoprophylaxis isn't available
- a potential vaccine is currently being developed
51
is there an effective vaccine for malaria?
- no, only immunity is a result of multiple infections
52
How many malaria cases are there in the world?
- about 3.3 billion people (half world's pop) are at risk for malaria
- 250 mill malaria cases and nearly one million deaths each year
- In Africa, 1 in 5 childhood deaths are due to effects of malaria
- An African child has an average b/t 1.6-5.4 episodes of malaria fever each year
53
What is the vector for Malaria?
- mosquitoes of the genus Anopheles -> only females carry this!
- 5 species that infect humans (Plasmodium falciparum most serious)
- endemic in SE US until 1940s (most cases in US now are airport malaria)
- Spread by bite of mosquito that was previously infected from a human blood meal
- parasited multiply within liver cells and RBCs
54
How long does it take for malaria to reach body system after bite? How long does it take to be systematic?
1-2 hours
| - 13-35 days to be sx
55
What are the four species responsible for human malaria?
- plasmodium vivax: most widely distributed
- Plasmodium malariae- comparatively rare - temperate areas and subtropics
- Plasmodium ovale: relatively uncommon, found in Asia, Europe and S. America
- Plasmodium falciparum: predominates throughout all tropical areas -> very often lethal
56
What does plasmodium vivid attack?
- reticulocytes
| - may become symptomatic 6-12 months after leaving an area with malaria, can be dormant for years
57
What does Plasmodium malariae attack?
- attacks mature red cells, after the acute infection, the infection becomes chronic and can persist for years
58
What is unique about Plasmodium ovale?
- can be dormant for years
59
What cells does Plasmodium falciparum invade?
invades all red cells irrespective of age of red cells -> cells agglutinate forming thrombi and emboli
60
Where is Plasmodium knowlesi found?
- newly identified
| - found in SE Asia (70% of cases of malaria)
61
What are the typical Malaria sxs and when do they start?
- onset 10-14 days up to 1 month with P. falciparum, 18-42 days occasionally 6 months to a year with other types
- chills
- night sweats
- fever
- HA
- muscle pain
- cough and chest pain
- splenomegaly in chronically infected pts
- hepatomegaly in chronically infected pts
62
What is congenital malaria and when should it be considered?
- it should be considered in febrile newborns and infants from women who could have been infected during their pregnancy
- malaria infection during pregnancy can result because the mother become infected during pregnancy, but it can also result from an infection acquired months or years before
63
What are ways to prevent malaria?
- vector control: reduce stagnant water, spraying with insecticide
- Application of DEET
- Mosquito nets
- vaccines: under development, no completely effective vaccine
64
Malaria tx and prophylaxis?
- chloroquine (most strains of Plasmodium show resistance) -> safe during pregnancy
- Atovaquone & proguanil (Malarone)
- Hydroxycholoroquine (Plaquenil)
- Doxy (can be used with cholorquine)
- Mefloquine (Larium): safe with pregnancy
65
What 2 malaria txs and prophylaxis are safe with pregnancy?
- Chloroquine and Mefloquine
66
When should malaria be considered?
- in all cases of fever in an area with high transmission of malaria
67
What are the DOC for tx of Malaria?
- first loading dose of chloroquine or atovaquone should be admin. immediately after collecting the blood specimen, even w/o waiting for its report
- In areas with high transmission of P. falciparum malaria -> chloroquine alone as presumptive tx may not be enough -> Atovaquone should be first choice
68
DOC for Malaria prophylaxis?
-chloroquine phosphate 500 mg weekly, continue 6 weeks after leaving area:
+ Fansidar (25 mg pyrimethamine and 500 mg sulfadoxine) weekly in areas with chloroquine resistant P. falciparum
or
Primiquine phosphate 26.3 mg daily, start 1-2 days before travel and continue 7 days after leaving area
69
What causes Toxoplasmosis?
- Toxoplasma gondii
- it's a coccidian protozoan of worldwide distribution that infects a wide range of animals and birds but doesn't appear to cause disease in them
- Felines are the only animals that can complete its reproductive cycle
70
How prevalent is Toxoplasmosis in the U.S.?
- it is considered to be the 3rd leading cause of death attributed to food borne illness in the US
- more than 60 mill men, women and children in the US carry the Toxoplasma parasite
- Very few have symptoms because the immune system usually keeps the parasite from causing illness
71
Pathogenesis of Toxoplasmosis (in the cat -> human)?
- oocysts develop in the cat GI tract, pass into the gut lumen of the cat, and pass out via the feces
- These cysts can then be ingest by other creatures, including humans (changing the litter box)
72
Pathogenesis of Toxoplasmosis once the human is infected?
- The oocyst opens in the human's duodenum and releases the sporozoites
- These pass through the gut wall, circulate in the body, and invade various cells, especially macrophages
- They multiply, break out, and spread the infection to lymph nodes and other organs
- They penetrate nerve cells, especially of the brain and eye, where they multiply slowly to form tissue cysts, initiating the chronic stage of disease
73
Sources of toxoplasmosis?
- 10% of lamb consumed by humans contain cysts
- 25% of pork consumed by humans contain cysts
- Direct contact with any material contaminated with infected cat feces may result in ingestion of oocysts - and it can be transmitted to food by infects
74
Sxs of Toxoplasmosis?
- in immune competent pts: most will be asymptomatic
- immune compromised pts - can cause: hepatitis, pneumonia, blindness, and severe neuro disorders
- sxs similar to those of the flu or mono, occur in immunocompetent pts such as:
body aches
swollen lymph nodes (bilaterally)
HA
fever
fatigue
occasionally a sore throat
75
When does a congenital infection of toxoplasmosis develop?
- develops only when non-immune mothers are infected during pregnancy
- usually causes severe congenital defects
- The incidence and severity of congenital toxoplasmosis varies with the trimester during which infection was acquired
- B/C tx of the mother may reduce the incidence of congenital infection and reduce sequelae in the infant, prompt and accurate dx is important
76
What can toxoplasmosis congenital infection lead to?
- leads to stillbirths, chorioretinitis, intracerebral calcifications, psychomotor disturbances, and hydrocephaly or microcephaly
- Prenatal toxoplasmosis is a major cause of blindness and other congenital defects
77
Sxs of congenital infection of toxoplasmosis?
Sxs may include:
- enlarged liver and spleen
- diarrhea or vomiting
- chorioretinitis
- feeding problems
- jaundice
- low birth weight
- vision problems
- hearing loss
- skin rash at birth
78
Ways that a pregnant mother can contract toxoplasmosis?
- a fetus may contract toxoplasmosis through the placental connection with its infected mother
- the infected mother may be infected by improper handling of cat litter or handling or ingesting contaminated meat
79
Toxoplasmosis Dx lab tests?
- Specimes: serology ->
* ***Sabin-Feldman dye test: gold std, but only a few labs run it
- ELISA: std test for most labs -> this is very effective
80
Tx of toxoplasmosis?
- acute infections can be tx with combo of pyrimethamine and either sulfadiazine or clindamycin
- Leucovorin should be given to all pts receiving pyrimethamine (protects bone marrow)
81
What is the tx for toxoplasmosis in pregnancy?
- spiramycin (Rovamycine) 1-2 grams BID is recommended, continued until delivery
82
Prevention of Toxoplasmosis?
- Transplacental infection of fetus has long been recognized. Domestic cats have been identified as hosts
- Wear gloves when gardening or handling soil
- Avoidance of human contact with cat feces is impt in control, particularly for pregnant women with negative serologic tests
- Since oocysts usually take 48 hours to become infective, daily changing of cat litter (and its safe disposal) can prevent transmission
- Pregnant women should avoid all contact with cats, particularly kittens
- Don't eat raw or undercooked meat
- cover children's sandboxes
83
What helminths are we worried about in the US?
- Nematodes:
pinworms, hook worms, round worms
- cestodes: tape worms
- Trematodes: flukes (very rare in US)
84
How is the pinworm spread?
- (also known as Enterobius vermicularis)
- spread fecal-oral route; self contamination and internal reinfection:
worms reside in cecum, colon -> crawl out of anus at night
- worldwide, but low morbidity
- seen in school children age 5-1- and uncommon in children
85
Sxs of pinworm infection?
- itchy butt, squirming when sitting (rarely worms get in vaginal canal)
86
Life cycle and transmission of Pinworm?
- after ingestion, eggs hatch and release larvae in small intestine
- adult worms establish in cecum and appendix
- Gravid females migrate to rectum onto perianal skin to deposit eggs (usually at night)
- one worm can produce 10,000 eggs
87
Dx of pinworms?
- stool for ova and parasites
- pinworm prep (cellophane tape test):
wrap 3" piece of clear scotch tape around glass slide (sticky side out) and touch the slide to the pt's perianal skin in 4 quadrants
- Examine under a microscope to find pinworm eggs. The best sample is collected either in early morning before bathing or several hours after going to bed
88
Tx of pinworms?
- Mebendazole (Vermox) >= 2 years: 100 mg PO single dose, may repeat in 2-3 weeks
or
Albendazole >=2 years: 400 mg PO single dose; may repeat in 2 weeks
- Tx the whole family!!!
89
Hygiene measure in tx of Pinworm?
- infxn not indicative of poor personal hygiene, common childhood infection
- Hand washing
- discourage child from sucking thumb, biting nails, and scratching
- trim nails
- wash bedding and garments in hot water promptly and avoid shaking
90
Epidemiology of Ascariasis (round worms)
- Ascaris infection is very common, especially in the tropics, hundreds of millions of people are infected
- in the US, most cases occur in the southern states
- most common in children 2-10 y/o
91
Transmission of round worms?
- ingestion of contaminated food/water
| - children playing in contaminated soil
92
Life cycle of round worms?
- when ingested ova hatch in small intestine and release larvae
- migrate in blood or lymphatics to lungs within 4 days
- after 10 days in the lung they mature, ascend the bronchial tree and get swallowed
- mature worms attach to jejunum
- female worms produce 200,000 fertilized eggs/day
93
Clinical presentation of round worms?
- cough, abdominal discomfort: anorexia, nausea, diarrhea
- intestinal obstruction
- biliary colic (can clog up duodenum and biliary duct)
94
Lab dx of round worms?
- dx is usually made microscopically by detecting eggs in the stools
- the egg is oval with an irregular surface
- occasionally, the pt sees adult worms in the stools
95
Tx of round worms?
- mebendazole 100 mg BID for 3 days or
- Albendazole 200 mg PO single dose
or
- Pyrantel: 11 mg/kg PO single dose for pregnancy
- alt second line: Ivermectin >15 kg 150 mc/kg single dose
- may have to remove with surgery
prevention: proper disposal of feces, and good handwashing
96
when and where would you likely get infected by a hookworm (Necator americanus)?
- an est. 576-740 mill people in world are infected with hookworm
- once was widespread in US, particularly in the SE region
- walking barefooted on soil predisposes to infection. An impt public health measure was requiring children to wear shoes to school
97
Where at on the body is hookworm infection likely to occur?
- humans are infected when filariform larvae in moist soil penetrate the skin, usually the feet or legs
98
Pathogenesis of hookworm?
- migrate into blood vessels and are carried by the blood to the lungs. Migrate into he alveoli and up the bronchi and trachea, and then are swallowed (takes 8-21 days)
- they develop into adults in small intestine, attaching to wall with cutting plates (hooks)
- They feed on blood from the capillaries of the intestinal villi
(6-8 weeks after infection eggs will become detectable in the bowel, this can persist for years)
99
What is the major damage due to from hook worm infection? Clinical findings?
- due to loss of blood at the site of attachment in the small intestine. Put to 0.1-0.3 mL/ worm can be lost per day - blood is consumed by worm and oozes from site in response to anticoagulant made by worm
- weakness and pallor accompany the microlytic anemia caused by blood loss
- skin penetration produces a focal pruritic maculopapular eruption at site (ground itch) (this will resolve on its own in a few days)
- mild cough and pharyngeal irritation
- N/V, diarrhea, and midepigastric pain
100
Dx of hookworm?
- made microscopically by observing eggs in the stools
- occult blood in stools is frequent
- ***Eosinophilia is typical
101
Tx and prevention of hookworms?
- both albendazole and mebendazole are effective
| - prevention: disposing of sewage properly and wearing shoes
102
What causes trichinosis?
| impt properties of this organism?
- Trichinella spiralis
- any mammal can be infected, but pigs are most important reservoirs of human disease in US (except Alaska, where bear constitute as reservoir)
- Humans are infected by eating raw or undercooked meat containing larvae encysted in muscle
103
Where does Trichinosis end up in body?
- the larvae excyst and mature into adults within mucosa of small intestine
- eggs hatch within adult females, and larvae are released and distributed via the bloodstream to many organs; however they develop only in ***striated muscle cells
- within these ***nurse cells they encyst within a fibrous capsule and can remain viable for several years but eventually calcify (this allows for concealment from immune system)
104
Pathogenesis and clinical findings of Trichonisis?
- a few days after eating undercooked meat, usually poor, the pt experiences diarrhea (severity is related to number of larvae ingested)
- 1-2 weeks later: fever, muscle pain (most common complaint), periorbital edema and eosinophilia
* **subungual splinter hemorrhages or conjuntival or retinal hemorrhages are an impt dx criterion
- signs of cardiac and CNS disease are frequent, because the larvae migrate to these tissues as well
- death (which is rare), is usually due to congestive heart failure or respiratory arrest
105
Lab dx of Trichinosis?
- muscle bx reveals larvae w/in striated muscle
- serologic tests: ELISA, indirect immunofluorescence, and latex agglutination are reliable; results can be confirmed with western blot
106
Tx and prevention of Trichinosis?
often self limited and not reqd
- symptomatic- steroids (help with discomfort) plus albendazole or mebendazole
- prevention: the disease can be prevented by properly cooking pork or freezing the meat and by feeding pigs only cooked garbage
107
What are the 2 impt human pathogens in the genus Tania (tapeworm)
- T. solium (pork tapeworm)
| - T. saginata (beef tapeworm)
108
Morphology of tapeworm?
- hav head, neck, and segmented body
| - each segment is called a proglottid (each proglottid can reproduce eggs asexually)
109
Lifecycle of tapeworms?
Cattle or pigs ingest vegetation that is contaminated w/ eggs or proglottids
- humans become infected by eating infected undercooked meat
- they attach to small intestine and develop proglottids
- This occurs over 2 months and can survive for years in the small intestine
110
Clinical findings of tapeworms
- most pts with adult tapeworms are asymptomatic, but malaise and mild cramps can occur
- in some, proglottids (segment or joint of tapeworm) appear in the stools and may even protrude from anus
111
Dx of tapeworms?
- ID of T. saginata consists of finding gravid proglottids with 15-20 uterine branches in the stop
- eggs are found in stools less often than proglottids
112
Tx and prevention of tapeworms?
- Praziquantel (Biltricide): 5-10 mg/kg orally one time
- prevention involves cooking meat adequately and disposing of waste properly so that cattle can't consume human feces
- most cases in USA are imported
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How should you be precautious when you go traveling to 3rd world countries?
- use DEET, don't drink the water, or us ice
- Boil it, cook it, peel it or forget it
- Be suspicious when your pts travel and come back ill or get ill soon thereafter
- Be really suspicious of odd infectious signs in immunocompromised pts
- wear shoes, especially when you vacation in South or in the tropics
- give pts chipper for prophylaxis
