MODULE 1 Unit 4: Laboratory Diagnosis of Parasitic Infections

Question 1

There are two (2) approaches in the diagnosis of parasitic infections: clinical and laboratory.

Answer 1

1. Clinical Diagnosis
2. Laboratory Diagnosis

Question 2

The clinical manifestations of parasitic diseases are so (?) that in most instances diagnosis based on symptomatology alone is inadequate. .

Answer 2

non-specific

Question 3

Although, an experienced physician may recognized characteristic signs and symptoms of certain parasitic diseases, the symptoms in (?) may be so confusing that no clear clinical picture is presented. This provides provisional diagnosis only

Answer 3

atypical cases

Question 4

Physician also suspects that the person has an infection rather than another type of illness based on patient

Answer 4

clinical history.

Question 5

It is designed to discover epidemiologic risk factors such as, but not limited to

Answer 5

past medical history, place of residence, travel, occupation, outdoor activities, family, food, and drinking water

Question 6

Specific examples of the importance of each of these follow.

• (?) should be suspected in a patient with unexplained fever and with the history of travel to rural area in Palawan.
• A history of hiking and drinking stream water is classically associated with (?).
• A gastrointestinal disease characterized by abdominal pain and diarrhea that follows after eating uncooked freshwater or brackish water fish may be associated with (?)

Answer 6

Malaria
giardiasis
Capillaria philippinensis infection

Question 7

A parasitology laboratory uses appropriate test method to be able to:

• Confirm or rule out a (?) that the disease is parasitic in nature.
• Identify (?( infection

Answer 7

clinical suspicion
unsuspected

Question 8

To confirm means to state that the disease is due to (?), and what species of parasite is present.

To rule out means to (?) as the cause of the disease.

Answer 8

parasitic infection
exclude or to eliminate parasite

Question 9

Unrecognizedorsubclinicalinfectionsposeathreatbecause manyparasitescanbetransmittedwhensymptomsare either

Answer 9

mildortotallyabsent.

Question 10

Accurate diagnosis of a parasitic disease provide (?) thus preventing possible complications that may arise. It can also provide accurate (?) that are important in the surveillance and monitoring of diseases.

Answer 10

prompt treatment
prevalence and incidence

Question 11

Laboratory diagnosis of parasitic infections is done either by

Answer 11

direct or indirect methods

Question 12

involves the demonstration of the parasite (e.g., adults, eggs, larvae, cysts, or trophozoites), or parasite components (e.g., antigens and DNA) in the specimen. This provides definitive diagnosis of parasitic infection.

Answer 12

Direct method

Question 13

tests for the evidence of parasitic infection other than actually finding the organism itself. This provides only presumptive evidence of infection.

Answer 13

Indirect method

Question 14

Parasitic infections are usually diagnosed by examination of a specimen/ material under the microscope.

Answer 14

Microscopic method

Question 15

Microscopic method is basically a two-step process:

(1) detection of the (?), and
(2) identification based on

Answer 15

parasite
distinctive morphologic characteristics

Question 16

Among others factors, this requires the availability of (?) and a well-trained and experienced (?).

Answer 16

good microscope
microscopist

Question 17

The need for highly invasive procedures to collect samples g. tissue, which may induce medical complications, undermines the utility of this method.

Answer 17

Microscopic method

Question 18

The most common procedure performed in the area of parasitology is the examination of a stool specimen for

Answer 18

ova and parasites (O&P exam)

Question 19

refers to the egg stage of select parasites and parasites encompass the other morphologic forms that may be present

Answer 19

ova

Question 20

Appropriate specimen is examined microscopically by (?) for parasite diagnostic stage

Answer 20

direct wet mounts, wet mounts of concentrates, or permanent stains

Question 21

• Cysts/trophozoites of (?)
  -Oocysts of (?)
  -Eggs of (?)
• Rhabditiform larvae of

Answer 21

Entamoeba histolytica, Giardia lamblia, Balantidium coli

Cystoisospora belli, Cryptosporidium parvum, Cyclospora cayetanensis, Sarcocystis spp.

Ascaris lumbricoides, Trichuris trichiura, hookworm spp. Capillaria philippinensis, Diphyllobothrium latum, Taenia spp., Hymenolepis nana, Hymenolepis diminuta, Dipylidium caninum, Fasciola spp, Clonorchis sinensis, Opisthorchis spp, Fasciolopsis buski, Echinostoma ilocanum, heterophyids, Schistosoma japonicum, Schistosoma mansoni

Strongyloides stercoralis

Question 22

Being generally a (?), this remains as the gold standard in most laboratories especially in the diagnosis of common protozoan and helminth infections. However, it is characterized by low sensitivity when parasites are low in numbers such as in light infections ,or during pre-patent and chronic periods of infection, hence, direct microscopic examination may yield false negative results. Concentration technique circumvents this problem

Answer 22

simple and low cost technique

Question 23

Giardia lamblia trophozoites, Cryptosporidium spp., Cystoisospora belli, Strongyloides stercoralis and eggs of Fasciola hepatica or Clonorchis sinensis

Answer 23

Duodenal material

Question 24

Entamoeba histolytica

Answer 24

Sigmoidoscopy specimen

Question 25

Enterobius vermicularis

Answer 25

Perianal swab

Question 26

Plasmodium spp., Babesia spp., Leishmania spp., Trypanosoma spp. Wuchereria bancrofti, Brugia malayi, Loa loa, Mansonella spp.

Answer 26

Blood

Question 27

Trichomonas vaginalis, Wuchereria bancrofti, Schistosoma haematobium.

Answer 27

Urine

Question 28

- Paragonimus westermani - Occasionally, larvae of Strongyloides stercoralis, Ascaris lumbricoides, and hookworm spp.

Answer 28

Sputum

Question 29

Trypanosoma brucei, Naegleria, Acanthamoeba

Answer 29

Cerebrospinal fluid

Question 30

Trichomonas vaginalis

Answer 30

Genital tract specimen

Question 31

Muscle biopsy specimen: Trichinella spiralis

Answer 31

Tissue and aspirates

Question 32

Histopathological examination of brain: Naegleria and Acanthamoeba

Answer 32

Tissue and aspirates

Question 33

Spleen and bone marrow aspirate: Leishmania donovani

Answer 33

Tissue and aspirates

Question 34

Duodenal aspirates: Trophozoites of Giardia lamblia

Answer 34

Tissue and aspirates

Question 35

Liver pus: Trophozoites of Entamoeba histolytica in cases of amebic liver abscess

Answer 35

Tissue and aspirates

Question 36

Culture methods using xenic or axenic media have been described for some protozoan parasites:

Answer 36

Trichomonas vaginalis, Leishmania spp., Trypanosoma cruzi, Entamoeba histolytica, Acanthamoeba spp., or Naegleria fowleri.

Question 37

is examined microscopically. This approach may be helpful when routine procedures have failed to provide a diagnosis.

Answer 37

Material from culture

Question 38

But few clinical laboratories undertake the task because of :

Answer 38

infrequent requests, lack of familiarity with methods, the need for special equipment, supplies, and reagents, and the waiting period for several days or weeks for the result.

Question 39

Culture protozoa grown in association with an unknown microbiota are called a (?).

Answer 39

xenic culture

Question 40

If they are grown in association with a single known bacterium, the culture is (?)

Answer 40

monoxenic

Question 41

if the culture contains several identified bacteria, then it is (?).

Answer 41

polyxenic

Question 42

If protozoa are grown as pure culture without any bacterial associate, the culture is (?).

Answer 42

axenic

Question 43

(?) is used for maintaining QC strains and for research purposes.

Answer 43

Axenic culture

Question 44

(?) may be used as a supplemental diagnostic procedure.

Answer 44

Xenic cultures

Question 45

This is a method for diagnosing a disease in humans by inoculating the specimen suspected of harboring causative parasite into a laboratory-bred, parasite-free animal of a different species. where the parasite is allowed to multiply. The laboratory animal is later microscopically examined for the presence of the parasite.

Answer 45

Xenodiagnosis

Question 46

In the diagnosis of (?), an uninfected reduviid bug is allowed to feed on patient's blood and the bug’s feces is then examined to observe for the presence of Trypanosoma cruzi.

Answer 46

Chagas' disease

Question 47

In the diagnosis of Chagas' disease, an uninfected reduviid bug is allowed to feed on patient's blood and the bug’s feces is then examined to observe for the presence of (?).

Answer 47

Trypanosoma cruzi

Question 48

Muscle tissue form a patient suspected of having (?) is fed to uninfected rat.

Answer 48

trichinosis

Question 49

The rat is then checked, after the appropriate time, for the presence of (?), particularly in the diaphragm.

Answer 49

Trichinella spiralis larvae

Question 50

This enables a diagnosis if very low numbers of parasites occur in the specimen. However, because a period of incubation between infection of the laboratory animal and examination is necessary, there is a long period of time until the final result. This procedure is rarely requested and not available in most clinical laboratories

Answer 50

Xenodiagnosis

Question 51

[Greek xenos, stranger, alien; + diagnosis)

Answer 51

Xenodiagnosis

Question 52

Specimen may also be examined grossly for parasite stage that are large enough to be seen by the naked eye, such as some adult worms, and proglottids of tapeworms.

Answer 52

Macroscopic examination

Question 53

for diagnosis of parasitic infections

Answer 53

Immunodiagnostic methods

Question 54

Immunodiagnostic methods for diagnosis of parasitic infections are basically of two types: (a) [?], and (2) [?].

Answer 54

(a) antigen detection, and (2) antibody detection.

Question 55

They permit batch processing, and do not require experienced microscopists.

Answer 55

Immunodiagnostic method

Question 56

Immunoassays that test specimens for the presence parasite antigens use known commercially prepared specific antibodies.

Answer 56

Antigen detection

Question 57

There are limited number of pathogenic parasites that can be diagnosed by antigen detection test.

Answer 57

Antigen detection

Question 58

Stool: Giardia lamblia, Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar group

Answer 58

Antigen detection

Question 59

Blood or serum : Plasmodium spp., Wuchereria bancrofti

Answer 59

Antigen detection

Question 60

Vaginal swabs: Trichomonas vaginalis

Answer 60

Antigen detection

Question 61

Test formats for antigen detection methods include:

Answer 61

direct fluorescent antibody (DFA), enzyme immunoassay (EIA), and lateral flow (immunochromatography) assays (LFAs).

Question 62

methods are more reliable and a positive test result is indicative of current infections.

Answer 62

Antigen detection

Question 63

In general, they have good or superior sensitivities and specificities, are easy to use and have quicker turnaround times when compared to routine microscopic examination.

Answer 63

Antigen detection

Question 64

is performed to determine the presence of antibodies

Answer 64

blood (serum) test

Question 65

which is an immune response formed against parasitic antigens, to provide evidence of infection.

Answer 65

antibody

Question 66

They are recommended in the diagnosis of infections caused by parasites that reside in the host deep tissues and invasive techniques are necessary to obtain specimen which can pose some risk to the patient, or in occult infections where parasites cannot be isolated in the specimen.

Answer 66

Antibody detection (serology test)

Question 67

An (?)for parasitic infection may provide early detection when significant levels of antibodies are produced before the patent stage.

Answer 67

antibody test

Question 68

However, in some people, parasitic infections may not stimulate (?) or seroconversion may be delayed with onset of clinical symptoms.

Answer 68

antibody response

Question 69

The detection of against against a given parasite in a patient with no previous exposure and no recent history of travel to an endemic area can be considered a (?).

Answer 69

positive result

Question 70

A (?) may be produced when examining individuals from endemic areas.

Answer 70

false positive test

Question 71

It does not distinguish between active and previous infection because (?) may decline slowly and persist even after cure. Therefore, the results of antibody tests in the diagnosis of parasitic infections must be interpreted cautiously.

Answer 71

antibodies

Question 72

Historically, (?) for parasitic diseases have been plagued by low sensitivity and specificity, primarily owing to the complex antigenic nature of parasites and the possibilities for crossreactions from related species.

Answer 72

serologic procedures

Question 73

The introduction of newer test methods combined with the use of more (?)s is providing more accurate results.

Answer 73

highly defined antigenic component

Question 74

Many of the newer tests use the (?), although IFA, indirect hemagglutination (IHA), complement fixation (CF), and bentonite flocculation (BF) methods remain popular.

Answer 74

EIA or immunoblot (Western blot) format

Question 75

(?) for parasite identification offers high levels of sensitivity and specificity, ability to differentiate morphologically similar organisms, lack of reliance on subjective microscopic features, and may also be used to monitor the success of antiparasitic therapy.

Answer 75

Nucleic acid amplification tests (NAATs)

Question 76

However, several challenges exist for widespread implementation of (?), including the expense of reagents and equipment, need for sophisticated facilities and are prone to cross-contamination if proper processing precautions are not strictly enforced.

Answer 76

molecular diagnostics

Question 77

Different types of NAATs include:

Answer 77

polymerase chain reaction (PCR) and real-time reverse transcription (RT) PCR random amplified polymorphic DNA (RAPD) amplified fragment length polymorphism (AFLP) restriction fragment length polymorphism (RFLP) microsatellite marker method Luminex xMAP-based technology (areas of multianalyte profiling) loop-mediated isothermal amplification (LAMP)

Question 78

Other testing modalities

Answer 78

a. Skin test b. Radiologic examination c. Hematology

Question 79

are performed by injecting parasitic antigen intradermally and observing the reaction.

Answer 79

Skin tests

Question 80

In immediate hypersensitivity reaction, (?) is seen within 30 minutes of infection

Answer 80

wheal and flare response

Question 81

(?) seen after 48 hours of injection is called as delayed hypersensitivity reaction.

Answer 81

erythema and induration

Question 82

• Montenegro test:

Answer 82

Kala-azar (Leishmania donovani)

Question 83

• Bachman intradermal test:

Answer 83

Trichinellosis (Trichinella spiralis)

Question 84

• Casoni's test:

Answer 84

Hydatid disease (Echinococcus granulosus)

Question 85

These tests are used to look for some parasitic diseases that may cause lesions in the organs.

Answer 85

X-ray, Ultrasonography (USG) Magnetic Resonance Imaging (MRI) scan Computed Tomography (CT) scan.

Question 86

is frequently seen in hookworm infection and malaria.

Answer 86

Anemia

Question 87

is frequently present in helminthic infections.

Answer 87

Eosinophilia

Question 88

occurs in visceral leishmaniasis.

Answer 88

Hypergammaglobulinemia

Question 89

is seen in amoebic liver abscess.

Answer 89

Leukocytosis

Question 90

is the sum of all the activities necessary to produce consistently accurate and precise results.

Answer 90

Quality assurance (QA)

Question 91

In a diagnostic parasitology laboratory, it is a guarantee that the information in the laboratory result can be relied upon by the physician to confirm or rule out parasitic infections.

Answer 91

QA

Question 92

refers to a system in which there is continuous improvement in reliability, efficiency, and utilization of laboratory services

Answer 92

Quality assurance

Question 93

It encompasses the entirety of the process beginning when a physician orders a laboratory test and ending with the physician interpreting the results

Answer 93

Quality assurance (QA)

Question 94

includes activities performed before the actual laboratory manipulation that influence the quality of laboratory results.

Answer 94

pre-analytical phase

Question 95

1. Pre-analytical phase:

Answer 95

a. Test ordering and request forms b. Proper specimen collection, storage, and transport c. Specimen receipt and accessioning d. Training of personnel

Question 96

The requesting physician must have an understanding of which laboratory tests are appropriate to order in the diagnosis, monitoring, or even screening for parasitic infection.

Answer 96

Test ordering and request forms

Question 97

Proper request forms must be used and contain information to correctly identify the

Answer 97

source/type of the sample, patient’s name and identification number, the physician’s name, and the date and time of sample collection.

Question 98

Where applicable, patients are given written and/or verbal instructions to facilitate collection of specimen for adequate detection.

Answer 98

Proper specimen collection, storage, and transport

Question 99

• Correct type of specimen and/or (?) of specimen collection • Appropriate (?) • (?). Certain medications and substances may interfere with the detection of parasites, thus should be avoided starting days before and continuing through the test period. • Acceptable amount or (?) of the specimen • Manner of specimen collection, storage, transport • Proper specimen (?) (source/type of specimen the patient’s name and identification number, the physician’s name, and the date and time of sample collection) • Use of (?) • (?) from sample collection to receipt and examination in the laboratory.

Answer 99

time specimen container Patient preparation volume labelling preservatives Time frame

Question 100

• Correct type of specimen and/or (?) of specimen collection • Appropriate (?) • (?). Certain medications and substances may interfere with the detection of parasites, thus should be avoided starting days before and continuing through the test period. • Acceptable amount or (?) of the specimen • Manner of specimen collection, storage, transport • Proper specimen (?) (source/type of specimen the patient’s name and identification number, the physician’s name, and the date and time of sample collection) • Use of (?) • Time frame from sample collection to receipt and examination in the laboratory.

Answer 100

time specimen container Patient preparation volume labelling preservatives

Question 101

Ensure that all specimens are accompanied with a complete laboratory request form and the information on the request form should correspond with the details of the patient and those on the specimen container.

Answer 101

Specimen receipt and accessioning

Question 102

Ensure that all specimens arrive in the laboratory as soon as after collection within time limit recommendation.

Answer 102

Specimen receipt and accessioning

Question 103

is maintained to track the specimen received into the laboratory.

Answer 103

record system

Question 104

The person advising the patient or medical staff must be adequately trained in all facets of specimen collection.

Answer 104

Training of personnel

Question 105

The person performing the parasitologic examination must be familiar with appropriate technical procedures to be used for each type of specimen and morphologic recognition and differentiation of parasites.

Answer 105

Training of personnel

Question 106

DIRECT methods of diagnosis for parasitic infections

Answer 106

Routine stool O & P exam Perianal scotch tape swab (enterobiasis) RT-PCR OptiMal test for malaria Xenodiagnosis

Question 107

INDIRECT methods of diagnosis for parasitic infections

Answer 107

Montenegro skin test WBC differential count MRI X-ray Rapid antibody test

Question 108

variables affecting Proficiency Test (PT) result

Answer 108

3. Sample handling and transport 4. Equipment management 5. Preparation of reagents 6. Carryover from previous sample 7. Personnel competency on detection and identification of parasites 8. Turnaround times 9. Transcription of results 10. Clinical management

Question 109

Exemption to variables affecting Proficiency Test (PT) result

Answer 109

Instruction for patient preparation Sample collection