Micro 9: Parasitic infection Flashcards
1
Q
Define infection
A
invasion by and growth of
pathogenic microorganisms
within the body
2
Q
Define disease
A
a disordered or incorrectly functioning organ, part, structure, or system of the body resulting from the effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavorable environmental factors; illness; sickness; ailment.
3
Q
Define parasite
A
organism living in or on the host and dependent on it for nutrition - causing damage
4
Q
Distinguish types of parasite
A
Endoparasite: protazoa and metazoa. = parasites that live inside the body of the host
Ectoparasite = parasites that live on the outer surface of the host and generally attach themselves during feeding
5
Q
What is protozoa
A
single celled organisms
Eukaryotes (genome within a nucleus, complex organelles in cytoplasm)
6
Q
t/f pathogenesis of protozoa is constant
A
F
7
Q
T/F protozoa infection is associated with eosinophilia
A
F
8
Q
What can be a route of protozoa infection
A
Some have insect vectors (eg malaria)
9
Q
Examples of protozoa
A
amoeba, coccidiae, ciliae, flagellates
10
Q
What are metazoa
A
Multicellular organisms (Helminths/worms)
11
Q
Differentiate the type of parasites that metazoa and protozoa are
A
Protozoa are often obligate intracellular parasites
Metazoa are free living, not within cells
12
Q
T/F all metazoa invade tissue
A
F. Some just inhabit gut (geohelminths), other invade tissues
13
Q
T/F metazoa is associated with eosinophilia.
A
T Eosinophilia – if invade blood
14
Q
2 types of amoeba. Which is dangerous
How are you infected by these
A
Entamoeba histolytica (=INVASIVE) , Entamoeba dispar (=COMMENSAL)
Infection occurs by ingestion of mature cysts in food or water, or on hands contaminatd by faeces
15
Q
How common is amoeba infection and how deadly
A
10% of world infected with E.histolytica
3rd most common cause of parasitic death
16
Q
Most common causes of parasitic death
A
Schichtomiasis, malaria, E. histolytica
17
Q
What is the incubation and the symptoms associated with E.histolytica (an amoeba) infection
A
90% of infections are asymptomatic; rest range from dysentery to amoeba liver abscess
Incubation as short as 7 days. Invasion occurs during first 4 months
18
Q
T/F e.histolytica also infects other mammals
A
F Humans are the only reservoir,
19
Q
Outline how E. histolytica gains access to the body and its effect on GI tract
A
enter the small intestine and
release active amoebic parasites (trophozoites),
These invade epithelial cells of large intestine –> ULCERS
20
Q
How can E. histolytica escape the GI tract and invade other structures
A
Infection can then spread from the
intestines to other organs, e.g. liver, lungs and brain, via the
venous system.
21
Q
What is the effect of invasive amoebiasis
A
most often causes an amoebic liver abscess, but may affect the lung, heart, brain, urinary tract and skin.
22
Q
Can the disease be spread by asymptomatic carriers?
A
Yes Asymptomatic carriers pass cysts in the feces and the
asymptomatic carriage state can persist indefinitely. Cysts
remain viable for up to 2 months.
23
Q
Diagnoss of amoebiasis?
Treatment?
A
Wet mount (look for in stools)
Nitroimidazole derivatives (act on trophozoite, but not on cysts)
24
Q
T/F coccidia infections, in the same way as E. histolytica (which is invasive amoeba), is only a human disease
A
F.Coccidial infection in humans are mostly zoonoses
25
Examples of coccidia
Plasmodium species (malaria)
Toxoplasma (toxoplasmosis, fine normally but v dangerous for foetus)
Cryptosporidium (diarrhoea in immunocompormised)
26
Route of infectin for coccidia
Mosquito borne
Cats
Water
27
Explain what is meant by a vector and list two specific examples, naming the diseases they transmit.
Malaria (plasmodium from coccidian protozoa) --> female Anopheles
Loa loa eye infection=loaiasis (=.filaria roundworm metazoa) Vector is chrysops.
28
Types of plasmodium
P. falciparum, P. malariae, P. ovale, P. vivax and P. knowlesi
29
Types of host for malaria (plasmodium)
humans and female Anopheles mosquitoes
Bite at night, breed in water
30
Stages of the life cycle that occur in human for malaria
Liver and blood stages
then mosquito stages too
31
Symptoms of malaria, and when do they appear
Variable.... 7 days to months
Fever, headache, chills, vomiting, muscle pain, paryoxysm
32
Complication of malaria
Cerebral malaria (swelling of the brain,seizures, coma)
Severe anemia (destruction of red cells)
33
Treatment of uncomplicated and complicated malaria
Uncomplocated:
-chloroquine
Severe:
-Artemisinin-based combination therapy (ACT) for P. Falciparum
34
Diagnosis of malaria
blood film, Giemsa stained
| or rapid antigen staining test
35
Toxoplasmosis infection type and route of infection. Who is it a problem in
Toxoplasma gondii
• eating undercooked meat of animals harboring tissue cysts
• consuming food or water contaminated with cat feces
• by contaminated environmental samples
• blood transfusion
• transplacentally from mother
to fetus.
PROBLEM IN PREGNANT WOMEN AND IMMUNOSUPPRESSED PEOPL
36
What is effect of toxopasma gondii in immunocompromised people
develop central nervous system disease, brain lesions, pneumonitis or retinochoroiditis among other risks.
37
How is toxoplasma gondii diagnosed
Serological test
38
What does cryptosporidium cause
diarrhea, fever, nausea, vomiting in humans
39
What is the typical patient for cryptosporidiu
very common in HIV+ patients presenting with diarrhea.
40
Diagnosis and treatment for cryptosporidium
Diagnosis: stool examination.
Treatment: fluid rehydration.
41
Example of ciliates
Balantidium coli
=Balantidiasis
42
Reservoir for balantidium coli
pigs, rodents, primates
Worldwide distruution
43
Symptoms for balantidium coli
Most people infected with Balantidium coli => no symptoms.
Immunocompromised patients may experience more severe signs and symptoms: persistent diarrhea, dysentery, abdominal pain, weight loss, nausea, and vomiting. If left untreated, perforation of the colon can occur.
44
Diagnosis of balantidium coli? is it treatable
Stool
Yes
45
Example of flagellates
Giardia lamblia (Giardiasis)
Trichomonas
Leishmania
46
How common is giardia lamblia- where is it found
Giardiasis: commonest, globally distributed, water-borne protozoal
infection.
47
What is a trophozoite
a growing stage in the life cycle of some sporozoan parasites, when they are absorbing nutrients from the host.
48
Outline life cycle of giardia lamblia
How can they be excluded from drinking water
Flagellated trophozooites attach by their suckers to surface of the
duodenal or jejunal mucosa
Ovoid cysts are able to survive standard chlorination procedures,
filtration is required to exclude them from drinking water
49
Symptoms from giardia lamblia
Most people infected with giardia lamblia => no symptoms.
ACUTE SYMPTOMS
```
Diarrhoea
Greasy stools that tend to float
Stomach or abdominal cramps
Upset stomach or nausea/vomiting
Dehydration (loss of fluids)
```
50
Treatment and diagnosis of giardia lamblia
Stool exam (cysts or trophozoites)
Treatment: metronidazole/tinidazole
51
How do you catch trichomonas compared to other flagellate giardia lamblia
Trichomonas= Exclusively Transmitted sexually
giardia lamblia= water- borne
52
How common Is trichomoniasis
It is estimated to be the most common, curable, non-viral sexually transmitted infection in the UK, with nearly 6000 new cases per year.
53
Where the infection of trichomoniasis
In women the organism is found in the vagina, urethra and paraurethral glands; in men infection is usually of the urethra.
54
Symptoms of trichomoniasis infection
F: 10-50% none. Vaginal discharge, vulval itching, dysuria, or offensive odour (non-specific)
Male: 15 to 50% of men are asymptomatic. discharge and/or dysuria.
55
Complication of trichomoniasis infection
Detrimental outcome on pregnancy and is associated with preterm delivery and low birth weight.
56
Implication of trichomoniasis for HIV+
There is growing evidence that trichomonas infection may enhance HIV transmission and there may be an increased risk of TV infection in those that are HIV positive.
57
Diagnosis and treatment of trichomoniasis
Diagnosis
Microscopy: Detection of motile trichomonads in swab/urine- Trichomonas Rapid Test
Treatment
metronidazole
58
Types of metazoa
Roundworms, flatworms, flukes
59
What type of organisms are metazoa
Metazoa= helminths
Complex muticellular parasites
60
What are the lifecycles of metazoan like
Cycles may involve insect vectors and intermediate hosts
61
T/f few metazoan infections are zoonoses
T For most, humans are the definitive host - few are zoonoses (acquired from
animals)
62
T/f you can consume a worm and have a helminth infection
F: Adult worms cannot multiply in man - number of adults related to infection (eggs cause the problem)
(lay eggs/microfilaria, larvae)
63
Highest burden of helminth infection what age
0-10
64
What is the commonest helminth infection worldwide
Ascariasis
Trichuriasis
Hookworm infection
Schistosomiasis
65
Examples of roundworms (=nematodes)
Ascaris, hookworm, Filaria, Strongyloides
66
Length of ascaris worm
The adult males are ~15-30cm long and females ~20-35cm
67
Life cycle of ascariasis
Adult worms in small intestine. Produce 240000 eggs per day
Eggs excreted in faeces. Fertile eggs become infective after 18 days-several weeks.
Infective eggs swallowed e.g water
Larvae hatch, invade intestinal mucosa, portal system to liver, systemic system to lung, penetrate alveolar walls.
Asecend bronchial tree, swallowed, and develop into adult worms in small intestine.
68
How long foes it take from ingestion of infective eggs to adult female.
How long do adult worms livee
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.
69
Symptoms of ascariasis
Infection with Ascaris lumbricoides often causes
no symptoms
Large number= abdominal pain/intestinal obstruction
Malnourishment (adults feed on content of small intestine) in large infections.
Penetration of lung can cause Loeffler's pneumonia. (pools of blood and dead epithelial cells clog air spaces in lungs)
70
Hook worm example, length (and how they attach) and symptoms
Ancylostoma duodenale
- Fe deficiency anaemia
- Gastrointestinal and nutritional/metabolic symptoms
- respiratory symptoms
about 1cm long and curved.
They are attached by their
buccal capsules to the villi
of the small intestine
71
Lifecycle of hookworm (a nematode)
Larvae are carried through the blood vessels 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.
(much the same as ascariasis)
72
Treatment for hookworm and diagnosis
albendazole and mebendazole
Stool
73
What is whipworm
Trichuris Trichiura
It's a nematode, a type of hookworm which is a type of roundworm
74
Lifecycle of whipworm (=Trichuris Trichiura )
The eggs hatch in the small intestine, and release larvae that mature and establish themselves as adults in the colon. The adult worms (approximately 4 cm in length) live in the cecum and ascending colon. The adult worms are fixed in that location
75
Symptoms of hookworm
Small amounts of whipworms might not cause any symptoms. But if there are hundreds of worms, then you might have bloody diarrhea and anemia due to severe vitamin and iron loss. The worms leave open wounds, which cause inflammation of the intestinal wall. In some cases you might also develop rectal prolapse.
76
Treatment and diagnosis of hookworm
albendazole and mebendazole
stool exam
77
What is lymphatic filariasis
The filarial category of roundoworms
can cause lymphatic obstruction leading to elephantiasis
```
lymphatic obstruction (especially in the legs) can progress to
elephantiasis – can also occur in arm, breast, scrotum
```
78
Example of a filaria
Brugia malayi
(one of the tree causative agents of lympatic filariasis)
Loasiasis (Loa loa, eyeworm)
79
Diagnosis and treatment of filarial roundworms
microfilariae are found mainly in the peripheral blood and can be found at peak amounts from 10 p.m. to 4 a.m. During the day, they are present in the deep veins, and during the night, they migrate to the peripheral circulation.
Blood smear or antigen detection with a immunochromatic test (card) or ELISA
albendazole and ivermectin
80
Life cycle of loaiasis
Fly takes blood meal from a person, and gives them larvae
The adults in subcutaneous tissue produce sheathed microfilariae, found in peripheral blood
Fly takes another blood mean and the microfilariae shed sheaths, penetrate fky's midgut and migrate to thoracic muscles
Then fly takes another blood meal and the larvae enter into another person's blood
81
How do Loaiasis cause eye worms
Females (~7cm) migrate through the subcutaneous tissues, may cross the front of the eye under the conjunctiva.
82
Example of flatworm (cestodes)
Taenia (Tapeworms)
83
T/F humans are the only definitive host for tapeworm, therefore they do not catch it from animals
F.... they catch from pig and beef. Humans are the only DEFINITIVE host, but doesn't mean it cannot live in other hosts temporarily between transfer
84
Symptoms of taenia infections
Most people => no symptoms or mild symptoms.
abdominal pain, loss of appetite, weight loss, and upset stomach.
Active passing of tapeworm segments
85
How long are the taenia flat worms
T. saginata taeniasis (size of the worm up to 10m)
T. solium or T. asiatica (~3 m).
T. saginata often experience more symptoms
86
Diagnosis adn treatment of taenia
Diagnosis:
Segment in stool or identifcation of eggs in stool
Treatment:
praziquantel
87
T/F for taeni, the eggs of the flatworm must be transferred directly from animal to human
F The eggs can survive for days to months in the environment
88
What is cysticercosis
TAENI SOLIUM
Commonest acquired cause of epilepsy worldwide
89
Example of fluke worm (=trematodes)
Schistosoma
90
Why is schistosomasis life cycle complex
Involves snail.
In water, the eggs hatch and penetrate snail
They are then released from snail and penetrate the skin
They migrate through different tissues and transform into male and female and eventually reside in venules.
Eggs moved towards lumen of SI and bladder/uterus
91
Symptoms, diagnoss and treatment of schistosomiasis
Symptoms: rash/itchy skin. Fever, chills etc. after couple of months
Adult worms, eggs travel to intestine, liver or bladder, cause inflammation or scarring
Diagosis stool
Treatment praziquantel
92
Ectoparasite examples
Sarcoptes scabeie
(scabies)
Pediculus humanus capitis (head louse),
Pediculus humanus corporis (body louse, clothes louse), and
Pthirus pubis ("crab" louse, pubic louse)
93
Treatment for scabies and diagnosis
Diagnostic
Appearance of rash + presence of burrows
Treatment
Scabicides
94
Stages of lifecycle for ectoparasites and route of infection
Three stages: eggs, nymphs and adult
| Transmission by direct contact
