W10 : Parasites Flashcards

Question

# **Types of parasites : tapeworms** How to diagnose Diphyllobothrium latum?

Answer 1

Microscopic examination of eggs on stool sample

Answer 2

Praziquantel Niclosamide | Worms can survive > 25 years in intestine, need effective drugs

Answer 3

Do not eat raw / undercooked fish dishes.

Answer 4

Through ingestion of eggs or larvae. When roundworms mature and grow out of larvae, they can multiply by sexually reproducing with each other in the GI tract. (intestinal phase)

Answer 5

Roundworms usually migrate out of the small intestine into **other organs** like **muscle, eyes**, and can even impact the **central nervous system. ** - This causes symptoms such as *muscle aches, joint pain, eye swelling*. ## Footnote bc human are incidental / accidental hosts, worm dont usually survive in human body. so worm want to migrate out of intestine to find more suitable conditions to survive.

Answer 6

False. For *Anisakis*, **marine animals** are the definitive hosts where L3 larvae develop into adults (but humans usually consume the larvae). For *Trichinella Spiralis*, **pigs / wild animals like bears** are the definitive hosts.

In both cases, humans are accidental and dead-end hosts. - Accidental/incidental : roundworms usually don't reside in humans - Dead end hosts : The larvae cannot fully develop and reach sexual maturity, usually die within 3 weeks after infection

Answer 7

Seafood : ocean fish and cephalopods (cod, pacific salmon, squid etc)

Answer 8

Acute abdominal pain

Characteristic symptoms - tingling / tickling sensation in throat and coughs up the roundworm (nematode) - may provoke life-threatening allergic reactions as larval nematodes burrow (hide) into gastric mucosa (stomach lining)

Answer 9

1 **hour** to 2 weeks after consuming seafood.

Answer 10

1. Conduct a morphological exam of worms coughed up 2. **Endoscopic exam** and extraction of worm from stomach

Answer 11

For less severe cases, anthelmintic drugs have been used with some success, but the worm will die and get passed out of body eventually.

For more severe pain, endoscopic removal is the best treatment.

Answer 12

1. Sufficient cooking to inactivate worms 2. Freezing and cooking to kill Anisakis Simplex (the larvae/baby version of the worm) 3. Do not eat raw / undercooked fish and squid

Answer 13

False. Though the worms are dead, consumers can still get allergic reactions from the ingested A. Simplex **antigens**

Answer 14

Trichnellosis can only pass on from one animal to another animal only if an animal eats an infected animal (predation / cannibalism).

Answer 15

Sylvatic cycle, as animals can prey on and scavenge infected wild animals.

Whereas in domestic cycle, pigs get infected through contaminated feed. However, with **better farming practices and proper farming system**, it rarely occurs in the domestic cycle.

Answer 16

Raw / undercooked pork or wild game (wild game : meat from an animal that is typically found in the wild, non domesticated)

Answer 17

No, human are dead-end hosts and its not through fecal oral route so

Answer 18

False. In the case of light infection, humans could be asymptomatic

Answer 19

Intestinal invasion (**1-2 days** after eating contaminated meat) : Nausea, vomiting, diarrhea, abdominal pain.

**Characteristic symptoms** **1 week** after infection, when larvae migrate into muscle tissues : eye swelling, Conjunctvitis (pink eye), aching muscles and joints

Answer 20

Cysts are clusters of larvae enclosed in a **protective wall**, so that larvae can survive harsh conditions.
Larvae encystment causes myalagia (ache and pain) and **weakness**, and symptoms eventually subside.

Answer 21

- Initial diagnosis relies on classic symptoms : eye swelling, muscle inflammation and fever - Confirmation by eosinophilia / **positive test for antibody** / muscle biopsy for T spiralise ## Footnote Eosinophilia happens when your body produces too many eosinophils. Eosinophils are one of several white blood cells that support your immune system. (Could occur due to allergic reactions / ingestion of parasite etc)

Answer 22

- Anthelmintic albendazole is effective in elimnating *intestinal worms and larvae* - Muscle aches : pain relivers - To control inflammation during larval migration : cortico**steriod**

Answer 23

1. Avoid undercooked pork and game meat 2. Deep freeze meat for **3 weeks** to kill trichinella (note : does not work in bear meat) 3. **Cook** meat thoroughly ## Footnote Temperature + avoid

Answer 24

False, bc the eggs that is passed in human faeces into water bodies needs to go through an intermediate host, **snails**, before it develops into cercariae (larvae), and **larvae goes into skin / flesh of animals**. Since **only the larvae is infectious to humans**, it means that it is indirect infection from animal to human. ## Footnote If directly ingesting eggs causes liver fluke infection, it would then be considered a human to human transmission. But in this case, its not since eggs need to develop in intermediate host first before it can be infectious.

Answer 25

Chinese / oriental liver fluke

Answer 26

Chinese / oriental liver fluke

Answer 27

- General symptoms : inflammation and intermitten obstruction of biliary ducts - Acute phase : fever, abdominal pain, nausea, **mild jaundice, hepatomegaly (enlarged liver)** - Long-standing infections : cholangitis (bile dict inflammation), cholelithiasis (gallstones in gall bladder / bile duct), cholangiocarcinoma (bile duct cancer), pancreatitis ( pancrea inflammation)

Answer 28

Southeast Asian liver fluke. - it affects millions of people in SEA (South East Asia), including Laos, Thailand, Vietnam - Cholangocarcinoma (bile duct cancer) caused by Opisthorchis viverrni kills 20,000 Thais a year !!!

Answer 29

False. Most cases are asymptomatic.

Answer 30

- Mild cases : abdominal pain, diarrhea / constipation, dyspepsia (burning, pain, or discomfort in the digestive tract)

Severe cases : 1. enlargement, obstruction & fibrosis of the liver 2. Jaundice 3. Cholangitis (bile duct inflammation) 4. Cholangiocarcinoma (bile duct cancer) 5. Cholecystitis (gall bladder inflammation)

Answer 31

1. Microscopic identification of eggs in stool sample. 2. Endoscopy examination of **small intestine** for eggs

Answer 32

1. Drugs : Praziquantel or albendazole 2. In the case of biliary obstruction (blockage in the bile duct system) : surgery may be required

Answer 33

1. Do not eat raw or undercooked fish 2. Cook fish to internal temp > 63°C 3. Freeze fish at -20°C or below for 7 days OR at -35°C or below for 15 hours

Answer 34

1. Stool exams and treatment of positive cases with Praziquantel → eliminate human host reservoir 2. Promote eating of cooked fish to prevent infection (but may be hard to change tradition) 3. Improve hygienic defecation to interrupt disease transmission → in some countries, ppl may j shit into nearby ponds etc.

Answer 35

It is a resting stage, a dormant and non-infectious form.

Answer 36

Oocysts undergo sporulation, which occurs for around 5-12 days in the external environment, outside of the human's body.

Answer 37

Cyclospora cayetanensis

Answer 38

False. Humans are the only known hosts (definitive hosts).

Answer 39

False, because ingestion of oocysts shedded in faeces will not directly lead to infection. The oocysts needs to sporulate in the environment first before it can be infectious. **Thus, it is an *indirect* human - human transmission**

Answer 40

**Less severe cases**: - Some people are asymptomatic - Symptoms linked to **intestinal disturbance** : Diarrhoea (sometimes explosive), loss of appetite, weight loss, nausea and tiredness

**More severe cases**: - Flu-like symptoms : headache, vomiting, fever, aching

Answer 41

Incubation period : 7 - 10 days

Infection period : days to months, may go away and come back

Answer 42

Young, old (Elderly), immunocompromised ## Footnote YOPI without the P (pregnant)

Answer 43

1. Direct consumption of contaminated water. 2. Fruits and vegetables that have been irrigated with contaminated water.

Answer 44

Idetification of **unsporulated oocysts** in **stool specime** by light / UV microscopy.

Answer 45

1. **Antibiotic** combination of Trimethoprim and sulfamethoxazole **(bactrim, septrim)** 2. Supportive treatment of fluid 3. Electrolyte balance and rest ## Footnote Points 2 and 3 : to make up for the electrolyte and fluid loss during diarrhea

Answer 46

1. Avoid food and water contaminated with faeces 2. Eat fresh fruits and vegetables from safe sources 3. Wash fruit and vegetables thoroughly - Note : washing does not kill and remove cyclospora cayetanensis 4. Boil water and cook food to destroy oocysts

Answer 47

Indirectly from human to human through the oral faecal route. - Oocyst (unsporulated) in faeces of human, which can get into water bodies, which then sporulate in water and contaminated water consumed by human.

Answer 48

1) Consumption of contaminated drinking water 2) Accidentally gulping down contaminated recreational water (in swimming pools) → nasty kids shitting into pool tsktsk ***[because contaminated water may be used for irrigation, or used during processing etc]:*** 3) Fruits and vegetables 4) Raw milk, sausages and offal (as cattle are also major hosts) 5) Wet / moist foods

Answer 49

1. Some are asymptomatic 2. Mild to profuse diarrhea (3-6 litres of watery stool per day), nausea, vomiting, **dehydration**, **fever & malaise (weakness)**

Answer 50

Young, old (Elderly), immunocompromised ## Footnote YOPI without the P (preg)

Answer 51

1. Prone to extraintestinal cryptosporidiosis (outside of intestine) involving : a. bile duct b. lungs c. middle ear

- Disease in some immunocompromised people become chronic, and could be life-threatening. ‼️ ## Footnote **In healthy person, it stays within intestine and recover in a week but in immunocompromised people, it can travel out of the intestine**

Answer 52

- Incubation period : 7 - 10 days - Infection duration : 2-14 days in healthy people, and diarrhea lasts for months in immunocompromised people.

Answer 53

1. Identification of oocysts in stool specimen by light microscopy 2. Acid-fast / specific fluorescent antibody stains

Answer 54

Drugs 1) Nitazoxanide (Alinia) 2) Azithromycin (Zithromax) **1 and 2 : to control Cryptosporidium**

3) Loperamide (imodium) → regulates gut motility ; fluid and electrolyte replacement (for diarrhea)

Answer 55

True, it is transmitted from animal (cat) to human.

Answer 56

1) Direct transmission : from cats (pets) to humans - through oocysts in faeces + humans never wash their hands properly - indirect contamination, when allowing pets into kitchen - cats may shit in the garden, and some people may plant their own produce at home → contaminated soil contaminate the produce

2) Indirect transmission : from wild cat → pigs → humans (by consumption of pork)

Answer 57

1. Feline species (cats) 2. Pigs 3. Humans

Answer 58

1. **From mother to foetus **: of a mother is infected with T gondii during / shortly before preganact, tachyzoites (rapidly multiplying stage) can infect fetus 2. During organ transplants / blood transfusion (rare)

Answer 59

True, most people are asymptomatic.

Answer 60

1. Immunocompromised infection (those with HIV / AIDS infection) 2. Organ transplant recipients 3. Infants (transmission from mom to baby)

Answer 61

1. Damage in eyes / brain 2. Infants infected before birth can be born retarded or with other mental / physical problems

Answer 62

1) Serological tests : immuniglobulin G (igG), an antibody for determining infection ;; igM to estimate time of infection

2) Direct observation / isolation of parasite in tissue, blood or other biopsy material ## Footnote 1. IgM Antibodies: Early Infection (Acute Phase): IgM is the first antibody produced by the immune system after an infection. In toxoplasmosis, IgM levels usually rise within 1-2 weeks of infection and peak during the acute phase. Decline: IgM levels begin to decline after the acute phase, typically becoming undetectable within a few months. In some cases, IgM can persist for longer periods (months to over a year), which can complicate interpretation. 2. The levels of IgG and IgM antibodies in a person infected with Toxoplasma gondii depend on the stage of infection. Here’s how they typically behave: 1. IgM Antibodies: Early Infection (Acute Phase): IgM is the first antibody produced by the immune system after an infection. In toxoplasmosis, IgM levels usually rise within 1-2 weeks of infection and peak during the acute phase. Decline: IgM levels begin to decline after the acute phase, typically becoming undetectable within a few months. In some cases, IgM can persist for longer periods (months to over a year), which can complicate interpretation.

2. IgG Antibodies: Later Infection (Chronic Phase): IgG antibodies are produced later in the infection, usually within 1-2 weeks after the initial IgM response. IgG levels rise during the acute phase and remain elevated for life, indicating prior exposure or infection. High IgG levels with low or absent IgM typically indicate a past infection rather than a recent one.

Answer 63

Sulfadiazine (antibiotic), used together with Daraprim (folic acid antagonist → substance that interferes with the function of folic acid, preventing cells from using it to synthesize DNA, effectively blocking cell division and often used as a medication to treat cancer or certain inflammatory conditions)

Answer 64

1. Cook food to safe temperatures (meat > 71°C; poultry > 74°C) 2. Peel / wash fruits and vegetables thoroughly before eating 3. Wash cutting boards, dishes, counters, utensils and hands with hot soapy water after contact with raw meat, poultry, seafood, or unwashed fruits/vegetables. 4. Wear gloves during any contact with soil / sand and then wash hands with soap 5. Feed cats with only canned and dried commercial food / well-cooked food, do not serve raw or undercooked meats.