Infections Lecture 8: parasitic infections and anti-parasitic drugs

Question 1

What are parasites

Answer 1

Living organisms that require intimate prolonged contact with another living organism to meet some of its basic nutritional needs

Unicellular protozoa to complex multicellular helminths
LICE, LEECHES, Scabies, Fleas

Question 2

What are the main anti parasitic drug classes and sub classes

Answer 2

1. Anti Helminths
   Anti-nematode
   Anti-cestodes
   Anti-trematodes
2. Anti protozoals
   Anti-amoebic’s
   Antimalarials

Question 3

what is an anti nematode and give an example of a drug in this class

Answer 3

Sub class of anti-helminths

Role: Immobilises the parasite to cause death

Example: Mebendazole

Question 4

What is an anti-cestode and give an example of a drug in this class

Answer 4

Sub class of anti-helminths

Role: Interferes with energy metabolism of parasite and glucose synthesis

Example: Niclosamide, Praziquantel (tape worm)

Question 5

Give an example of an Anti-trematode

Answer 5

Praziquantel

Question 6

Give an example of anti-protozoal drugs

Answer 6

Metarsoprol- sleeping sickness

Eflornithin- sleeping sickness

Metronidazole- anaerobic bacterial infection

Question 7

Give examples of anti amoebic and antimalarials

Answer 7

Anti-amoebic- Tinidazole and Metronidazole

Antimalarials- Chloroquine and deoxycycline

Question 8

Describe what Protozoa and give examples of where it causes diseases

Answer 8

Unicellular eukaryotic organism that feeds on bacteria and particles of nutrients on growing stage

example:
Malaria- parasitic protozoa plasmodium
Intestinal infection

Question 9

How does malaria normally work

Answer 9

Mosquito is infected and takes blood meal

Infects liver cell which will rupture and infect blood cells

Symptoms begin to show and uninfected mosquito taking infected blood can begin the whole cycle again

Question 10

What are the three types of malaria

Answer 10

P.falciparum

P.vivax
Adapted to lower temperature
Higher sensitivity to drugs

P.malariae

Question 11

What are the symptoms of malaria

Answer 11

Common violent fever lasting 6 to 8 hours

Recurs every two to three days

Anaemia and enlargement of spleen develop as disease progresses

Sweating, cough, nausea and vomiting, back pain, fatigue, headache

Question 12

How do you diagnose malaria

Answer 12

blood film

Question 13

how do you prevent malaria (prophylaxis)

Answer 13

Malarone: Atovaquone/proguinil hydrochloride

Chloroquine

Quinine + doxycycline

Question 14

What causes Amoebic dysentry and amoebiasis, what are the symptoms

Answer 14

Entamoeba histolytica

Mild diarrhoea to severe dysentry

Extra intestinal infections like liver abscesses- digests and liquifies human host cells (colon wall, neutrophils, liver cells)

Question 15

What are the treatment options for amoebic dysentry and amoebiasis

Answer 15

Metronidazole- first line, acute invasive amoebic dysentry

Tinidazole- active against cysts in lumen

Question 16

What causes Toxoplasmosis and how is it treated

Answer 16

Toxoplasma gondii

Treatment:
Self limiting
Pyrimethamine
Sulphadiazine 
Clindamycin
Corticosteroids

Question 17

What causes cryptosporidiosis, how its transmitted, symptoms and treatment

Answer 17

Causes: Cryptosporidium paruum

Transmission: spread from water, swimming lakes and pools

Symptoms:
Watery diarrhoea
Dehydration, weight loss, Fever, nausea or vomiting

Treatment:
Usually self limiting but dangerous immunocomprimsied

Question 18

What are the three different types of parasitic worms (HELMINTHS)

Answer 18

Cestodes- parasitic flatworms (tape worms)

Nematodes- Roundworms- whipworm, hook worms, pin worms

Trematodes- flukes, liver flukes and blood flukes

Question 19

How are these parasitic worms transmitted

Answer 19

Poorly cooked meat
Contaminated water
Faeces
Insects
Eggs or worms can enter through mouth, anus, nose or skin

Question 20

What are the actions the different helminths have

Answer 20

Most species attach to intestinal tract
Digestive enzymes to dissolve egg shell

Feed off host for nourishment and protection
Asymptomatic for months and years

Question 21

What are two types of cestodes

Answer 21

Cestodaria

Eucestoda

Question 22

What are the symptoms of cestodes

Answer 22

Upper abdominal discomfort

Diarrhoea

Loss of appetite

Often asymptomatic

Question 23

How do you treat cestodes

Answer 23

Taethicides

Niclosmaide

PRAZIQUANTEL

Question 24

What causes Nematodes (pin and threadworm) and what are the symptoms

Answer 24

Enterobius Vermiculans

Symptoms:
Itching
Scratching, transmit under nails

Question 25

How do you diagnose Nematodes

Answer 25

Seeing worms in perianal region or scotch tape test- sellotape around anus and look under microscope

Question 26

How do you treat nematodes

Answer 26

Mebendazole

Question 27

What are the cause and symptoms of hook worm nematodes

Answer 27

Cause: Ancylostoma duodenale or Necator americanus

Iron deficient anaemia

Diarrhoea, nausea, vomiting

Question 28

How do you treat hook worm nematodes

Answer 28

Mebendazole

Albendazole

Question 29

What causes nematode whip worms, symptoms, and treatment

Answer 29

Trichuris trichiura

Light infestation- asymptomatic
Heavy- bloody diarrhoea

Treatment: mebendazole

Question 30

What causes nematode round worms, its symptoms, complications and treatment

Answer 30

Ascaris lumbricoides

Larval stage- visceral damage, peritonitis and inflammation
Enlargement of liver or spleen, pneumonia

Complications:
obstruction of bolus of worms in bowels
obstruction of bile or pancreatic duct

Treatment:
Mebendazole

Question 31

How do you treat headline or scabies

Answer 31

Dimeticone lotion or liquid

Permethrin or ivermectin