[PARA10N] Lec 1: Introduction to Parasitology

Definitive Host

The organism which supports the development of the adult or the sexually reproductive stages of the parasite

Intermediate Host

The organism which supports the development of the immature or the asexual forms of the parasite

Biological vectors

Intermediate hosts like snails and insects are considered as ____________ since they are integral parts of the life cycle of the parasites supporting the development of the parasite.

Symbiosis

This occurs when two dissimilar organisms live together in an intimate association

Commensalism

An association between two organisms wherein only one benefits without harming the other.

Mutualism

Symbiotic relationship when two organisms of different species exist in a relationship in which each individual benefits from the activity of the other.

Parasitism

The relationship between two organisms when one lives on or in another organisms causing it some varying degree of harm.

Zoonoses/Zoonotic Diseases

Diseases that can be transmitted from animals to human

opportunistic parasites

Non-pathogenic organisms which can cause severe disease in immunocompromised individuals

Mechanical Vectors

Does not support the development of the parasite and only carries the parasite mechanically.

Endoparasites

Those who are living inside the hosts such as tapeworm consists of protozoans and helminths

Protozoan parasites

include the flagellates, amoebae, sporozoans and ciliates

Helminths

are the nematodes or roundworms, trematodes or flatworms/flukes, and cestodes or tapeworms.

Ectoparasites

Those who are living outside the host such as the blood sucking ticks

Vectors

Organisms that carries and transmits the parasite from one host to another

Reservoir hosts

Hosts that act as additional sources of the parasite other than the definitive hosts

Paratenic Hosts

Hosts that are not needed for the parasite’s development and growth

Accidental Hosts (incidental hosts/ "dead end hosts")

Host wherein the parasite can no longer complete their life cycle

Biosecurity

It is a strategic and integrated approach to analyzing and managing relevant risks to human, animal and plant life and health and associated risks for the environment.

Biosafety

The combination of work practices, primary containment devices, and laboratory design to reduce the risk of laboratory infection or release of a microbe to the environment.

Risk groups

Classifications that describe the relative hazard posed by infectious agents or toxins in the laboratory.

Biosafety Level 1

Level of biosafety suitable for work involving well-characterized agents not known to cause disease in healthy adult humans and of minimal potential hazard to laboratory personnel and the environment

Biosafety Level 3

Level of biosafety appropriate to work done with indigenous or exotic agents with a potential for respiratory transmission, and which may cause serious and potentially lethal infection.

Biosafety Level 2

Level of biosafety involving work with the broad spectrum of indigenous moderate-risk agents that are present in the community and associated with human disease of varying severity

Group 1 Risk Group

Risk group involving agents that are not associated with disease in healthy adult humans

Group 3 Risk Group

Risk group involving agents associated with serious risk or lethal juvenile disease to which preventive or therapeutic interventions may be available

Group 4 Risk Group

Agents that are likely to cause serious or lethal human disease to which preventive or therapeutic intervention are not usually available

Group 2 Risk Group

Agents associated with no risk to the community

1. Group 2 2. Group 3 3. Group 3 4. Group 4 5. Group 1

Identify the risk groups of the following microorganisms: 1. Salmonella typhi 2. Yersinia pestis 3. Mycobacterium tuberculoses 4. Ebola virus 5. Bacillus subtilis

Biosafety Level 3: hood, safety glasses, respiratory protection (sometimes N95), double gloves, specific gowns, and shoe covers.

What level of biosafety PPE do COVID 19 frontliners use?

Medical/Surgical masks

stipless masks that provide a barrier that prevents the transmission of an infectious agent between [for example] a health personnel and the patient.

Filtering Facial Piece (FFP) or Self-filtering respirator/mask

are useful to prevent the passage of particles larger than 0.6 microns, therefore preventing virions such as the SARS-COV 2 and bacteria that cause airborne diseases from penetrating.

Non-powdered gloves

These type of gloves are preferred since these avoid reactions with the alcohol-based handrub in use within the health-care facility

Molecular Diagnosis

Diagnosis that deals with the detection of the DNA of a parasite

Serological Diagnosis

Detection of the antibodies against the parasite or antigens of the parasite

Parasitological Diagnosis

Detection of the parasite

Blood and stool

What are the most common diagnostic specimens used in parasitology?

Stool

Specimen used in detection of the eggs and larval stages (helminths), cysts and trophozoites (protozoans)

20-40 grams (half the size of the thumb), 5-6 tbsp

How much stool is needed for fecalysis?

Artifacts

Generally referred to living or abiotic agents that are embedded in the stool samples and may mislead the microscopist because of their similarity to parasitic organisms

10% formalin, Polyvinyl alcohol, freezer/refrigerator

Give the three chemicals/tools in preserving stool

Charcot-Leyden crystals

Hexagonal bipyramidal structures localized in the primary granules of the cytoplasm of eosinophils and basophils

Plant hair (artifact), Hookform rhabditiform larvae, Strongyloides stercoralis rhabditiform larvae

Identify the three pictures and which picture(s) is the artifact

Undertilized Ascaris lumbricoides egg, plant cell (artifact), pollen grain (artifact), Taenia spp. egg

Identify the four pictures and which picture(s) is the artifact

Yeast (artifact), Giardia duodenalis, Fungal spore (artifact)

Identify the three pictures and which picture(s) is the artifact

Blood

Specimen used for detection of microfilaria (filariasis) and Plasmodium blood stages (malaria)

Time of spike in temperature

Blood samples for suspected malaria are preferably collected at what time?

False. Capillary blood is obtained via finger prick while venous blood is obtained via venipuncture

True or False: Capillary blood is obtained via venipuncture

No, it can cause hemolysis, 4-8˚C for up to 24 hours before the serum is separated

Can whole blood be frozen for storage? How long can whole blood be stored?

Ice, 7 days

Serum is usually transported in _____ and should only be stored for a maximum of ______