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USMLE And Medicals
Kings
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Kings
USMLE Cardiology Cases Part 1- A Must For A Great USMLE Score
~10.9 mins read
1.
Case: You have a patient who needs to use pseudoephedrine as a nasal decongestant. He is an older gentleman with BPH, hypertension, hyperthyroidism, and coronary artery disease, and urinary incontinence. Which one of these symptoms are NOT made WORSE by the pseudoephedrine?
A) Urinary incontinence. Due to contraction, you may actually help the symptom of urinary incontinence.
2.
Q) First, tell me about the differences between extrinsic vs. intrinsic hemolytic anemia and extravascular vs. intravascular hemolysis. (People get these terribly confused at first).
A) Listen, EXTRINSIC hemolysis means something is wrong OUTSIDE the Red Blood Cell (RBC). INTRINSIC hemolysis means something is wrong INSIDE the RBC. Extravascular hemolysis occurs when MACROPHAGES eat up the RBCs and Intravascular hemolysis occurs when the hemolysis occurs by various mechanisms WITHIN the circulation.
3.
Q) What kind of hemolysis is PNH, or Paroxysmal nocturnal hemoglobinuria?
A) It is a stem cell disorder, acquired, by sensitivity of hematopoietic cells, which have a reduction of decay accelerating membrane factor, so they get destroyed by complement. So, PNH is an INTRINSIC, INTRAVASCULAR (they are NOT removed by macrophages) anemia!
4.
Q) Pt. comes in with WARM hemolytic anemia. What kind of hemolysis is this?
A) Its MOA is IgG/C3b deposited on RBCs with extravascular removal by MACROPHAGES, which have the Fc receptors for IgG and C3b! Thus, this is an EXTRINSIC and EXTRAVASCULAR hemolysis.
5.
Case: Pt with sickle cell anemia. Same question, what kind of anemia is this?
A) The sickled cells cannot escape the Billroth cords in the spleen. Thus, they are removed extravascularly by MACROPHAGES. Thus, this is an INTRINSIC hemolytic anemia with EXTRAVASCULAR hemolysis!
6.
Case: Middle aged man, smoker, received synthetic heart valve replacement.. later, anemia occurs. What kind of anemia?
A) Schistocytes (broken RBCs) are seen because they break apart after hitting the plastic heart valves. Thus, we see an EXTRINSIC (not inherent with RBC formation), INTRAVASCULAR (within the circulation) hemolysis.
7.
True or False: At a constant EDV (end diastolic volume), epinephrine RAISES stroke volume.
A) True.
8.
True or False: Vigorous exercise increases BOTH EDV and Stroke Volume!
A) TRUE!
9.
Case: Pt. on propanolol. Does Stroke Volume decrease at CONSTANT EDV? Or will it change too?
A) Yes, EDV remains constant.
10.
Case: An older female with a pacemaker that malfunctions and speeds up while the patient is at rest. How will EDV and SV change?
A) Here, they BOTH decrease.
11.
Q) In which case will there be FOLATE deficiency and not vit B12 deficiency? (Pick either Crohn's disease, Chronic pancreatitis, or Pregnancy)
A) PREGNANCY! The other two result in vitamin B12 def. Think of the MOA of vit B12 uptake! (recall R factor in saliva, intrinsic factor in stomach, etc. )
12.
Q) relating to the previous concept, will small intestine bacterial overgrowth affect vit B12 absorption? HOW?
A) YES, by breaking up the intrinsic factor and vit B12 complex. (Note, folate is not affected)
13.
Q) The posterior cerebral artery distributes to the OCCIPITAL CORTEX via the basilar artery...so will an embolism from the VERTEBRAL artery occlude such that someone's eyesight is lesioned? Yes or NO? The NBME stresses pictures of the brain, so be ready to identify all the main diseases and which blood vessels distribute to its different parts!
A) Yes. All is true here.
Case: You have a patient who needs to use pseudoephedrine as a nasal decongestant. He is an older gentleman with BPH, hypertension, hyperthyroidism, and coronary artery disease, and urinary incontinence. Which one of these symptoms are NOT made WORSE by the pseudoephedrine?
A) Urinary incontinence. Due to contraction, you may actually help the symptom of urinary incontinence.
2.
Q) First, tell me about the differences between extrinsic vs. intrinsic hemolytic anemia and extravascular vs. intravascular hemolysis. (People get these terribly confused at first).
A) Listen, EXTRINSIC hemolysis means something is wrong OUTSIDE the Red Blood Cell (RBC). INTRINSIC hemolysis means something is wrong INSIDE the RBC. Extravascular hemolysis occurs when MACROPHAGES eat up the RBCs and Intravascular hemolysis occurs when the hemolysis occurs by various mechanisms WITHIN the circulation.
3.
Q) What kind of hemolysis is PNH, or Paroxysmal nocturnal hemoglobinuria?
A) It is a stem cell disorder, acquired, by sensitivity of hematopoietic cells, which have a reduction of decay accelerating membrane factor, so they get destroyed by complement. So, PNH is an INTRINSIC, INTRAVASCULAR (they are NOT removed by macrophages) anemia!
4.
Q) Pt. comes in with WARM hemolytic anemia. What kind of hemolysis is this?
A) Its MOA is IgG/C3b deposited on RBCs with extravascular removal by MACROPHAGES, which have the Fc receptors for IgG and C3b! Thus, this is an EXTRINSIC and EXTRAVASCULAR hemolysis.
5.
Case: Pt with sickle cell anemia. Same question, what kind of anemia is this?
A) The sickled cells cannot escape the Billroth cords in the spleen. Thus, they are removed extravascularly by MACROPHAGES. Thus, this is an INTRINSIC hemolytic anemia with EXTRAVASCULAR hemolysis!
6.
Case: Middle aged man, smoker, received synthetic heart valve replacement.. later, anemia occurs. What kind of anemia?
A) Schistocytes (broken RBCs) are seen because they break apart after hitting the plastic heart valves. Thus, we see an EXTRINSIC (not inherent with RBC formation), INTRAVASCULAR (within the circulation) hemolysis.
7.
True or False: At a constant EDV (end diastolic volume), epinephrine RAISES stroke volume.
A) True.
8.
True or False: Vigorous exercise increases BOTH EDV and Stroke Volume!
A) TRUE!
9.
Case: Pt. on propanolol. Does Stroke Volume decrease at CONSTANT EDV? Or will it change too?
A) Yes, EDV remains constant.
10.
Case: An older female with a pacemaker that malfunctions and speeds up while the patient is at rest. How will EDV and SV change?
A) Here, they BOTH decrease.
11.
Q) In which case will there be FOLATE deficiency and not vit B12 deficiency? (Pick either Crohn's disease, Chronic pancreatitis, or Pregnancy)
A) PREGNANCY! The other two result in vitamin B12 def. Think of the MOA of vit B12 uptake! (recall R factor in saliva, intrinsic factor in stomach, etc. )
12.
Q) relating to the previous concept, will small intestine bacterial overgrowth affect vit B12 absorption? HOW?
A) YES, by breaking up the intrinsic factor and vit B12 complex. (Note, folate is not affected)
13.
Q) The posterior cerebral artery distributes to the OCCIPITAL CORTEX via the basilar artery...so will an embolism from the VERTEBRAL artery occlude such that someone's eyesight is lesioned? Yes or NO? The NBME stresses pictures of the brain, so be ready to identify all the main diseases and which blood vessels distribute to its different parts!
A) Yes. All is true here.
14.
Case: A man comes in with urinary stones...a history of them. Name THREE places which you should identify on radiograph or a diagram where a stone can likely get stuck along the ureter. Up to 10 percent of folks get stones!
A) LARGEST of them is at the ureteropelvic junction. Next is the area of the Pelvic brim. The last area is the ureterovesical junction, (area where the ureter passes through the bladder wall.
15.
Case: You see a 28 year old male with unknown reasons for lymphadenopathy, weight loss, and these weird raised skin lesions all over his chest. Which one, (Kaposi's sarcoma, a CD4 count of 220, or a positive antibody test for HIV), confirms AIDS?
A) Kaposi's sarcoma. The USA standards are that you need a CD4 count under 200, regardless of symptoms...BUT, if you see something like Kaposi's sarcoma, an AIDS defining illness, you can identify it as AIDS.
16.
Case: You see a person with bipolar disease on Lithium. He has Diabetes insipidus as a long term consequence from SIADH. True or False for each:
1..will he show HYPERnatremia?
2...intracellular compartment swelling?
3...increased plasma osmolality?
A1) YES, from loss of free water.
A2) NO (think of osmotic properties)
A3) YES...
17.
Cases: 4 different patients with gout...
First guy is on a drug that work by blocking the renal reabsorption of uric acid. Is it sulfinpydrazone, probeneicd, BOTH, or NEITHER?
A) BOTH, think MOA...
18.
Case: Next guy with ACUTE gout runs in limping. Will you give allopurinol or indomethacin for the ACUTE gout?
A) INDOMETHACIN, an NSAID which blocks prostaglandin synthesis.
19.
Case: Another guy with gout walks in. He needs meds for chronic gout. You give colchicine. What is the MOA against the gout?
A) It blocks leukocyte migration AND phagocytosis secondary inhibition of tubulin polymerization.
20.
Case: Another person waltzes in with chronic gout. He has a weak GI tract. Which med, probenecid or colchine, are you worried about giving?
A..colchine...it can cause serious GI side effects.
21.
Case: Which common bug, H. flu, S. pneumo, or Staph. aureus, LACKS IgA proteases which help a bug infect mucosal surfaces?
A) Staph aureus.
22.
Name two out of many enzymes that S. aureus makes which degrade human cells for colonization...what do they do?
A) Think about the Identifying traits like Catalase positive and Coagulase positive. These two enzymes of S. aureus work thus:
Coagulase clots plasma. And catalase converts cellular Hydrogen peroxide to water and oxygen, limiting the cellular killing of the bacteria.
23.
Case: A friendly friend comes into your office complaining of symptoms from an acoustic neuroma at the cerebellar-pontine angle. What symptoms is he likely to show? And what two nerves are likely to be affected?
A) Vertigo, Auditory stuff, and facial muscle paralysis are seen. CN VII and VIII are often lesioned.
24.
Case: An aneurysm appears in the superior mesenteric artery at the level of LV2. Which is compressed, the left or right renal vein? Which is longer? Important since you will know which kidney is in danger.
A) The LEFT renal vein, which passes ANTERIOR to the aorta. The left renal vein is LONGER.
25.
Q) What is different about the drainage of the right ovarian vein and the left ovarian vein? Is there anything?
A) The RIGHT ovarian vein drains directly into the Inferior vena cava while the LEFT drains into the left renal vein first before the IVC.
26.
Q) Tell us about the MOA of the degradation of cortisol? Where does it occur?
A) It occurs in the liver, converted to tetrahydrocortisone. It is then converted into glucuronic acid via CONJUGATION. Now it is water soluble, and is then urinated out into the toilet or potty.
27.
Case: An older patient comes in with cataracts. Can it be due to sorbitol production in the lens? What common dx is associated with excess sorbitol production?
A) Yes, it is often due to diabetes mellitus.
28.
Case: A patient of yours named Jennifer Connolly steps on a nail in a house called "House of Sand and Fog." She suffers paralysis from Clostridia. Is there an exotoxin associated? What is the MOA?
A) Yes...the MOA is that an inhibitory neurotransmitter called GLYCINE is blocked from release from the CNS, causing tetanic paralysis.
29.
Case: A cases of a patient with a murmur...a diagram shows a crescendo-decresendo, ejection type, diamond shaped figure between S1 and S2. What valve is lesioned?
A) This is AORTIC stenosis. Both pulmonary and aortic stenosis occurs during systole. The sound diagram is evident when the blood rushes out thru the narrow opening.
30.
Q) We just spoke of aortic stenosis and the sound diagram. What about MITRAL STENOSIS, in relation to S1 and S2?
A)Opening snap, cresendo, decresendo, diamond/wedge shaped...you will see a cresendo wedge leading up to S1.
31.
Q) T/F. The aortic valve and pulmonic valve opens during diastole.
A) False, they CLOSE during diastole.
32.
Case: You are treating a patient with mitral regurg...how does the sound/time graph look like?
A) Try to imagine the mech of action (MOA), then you will not forget...this is a pansystolic or holosystolic murmur, so the graph will look like a rectangle, the line with zero slope, where the blood rushes back into the atria with a CONSTANT velocity.
33.
Q) Will tricuspid regurg look like mitral regurg on a sound vs. time graph?
A) Yes, both have the same MOA...think about it logically. They are coupled as are the pulmonary and aortic valves.
34.
Case: Another patient comes in with aortic REGURG...how will this sound/time graph look like? Please review in a cardio text, as my explanations are not the best without pics.
A) Think about what is happening...during DIASTOLE, there is an insufficient aortic value, so there is regurg, so then there is a high pitched blowing murmur AFTER S2, when the aortic valve does not close right as the heart is trying to fill the ventricles. You will see a descending wedge/triangle after S2.
35.
True or False: An S4 heart sound is shown on a graph superimposed a cardiac cycle graph. Is it associated with atrial contraction OR ventricular contraction?
A) ATRIAL contraction or atrial systole...also seen with a hypertrophic ventricule...also maybe a heart attack.
36.
Case: You see a cardiac cycle graph. Point to the exact place where you may see an S3....what is the MOA?
A) Right after the mitral valve opens, you may see an S3 as you hear the blood slam into the walls of the ventricle during diastole (rapid ventricular filling).
37.
Case) (Hint, this is the most posterior chamber in the heart). A woman with rust colored sputum, difficulty swallowing, cough, and a hoarse voice comes in. What heart disease does she have that we recently discussed? What is the mech. of action?
A) This is MITRAL STENOSIS...greater pressure need to overcome the stenosis results in a hypertrophy of LEFT ATRIUM. As this is most posterior, enlargement compresses the esophagus (difficulty swallowing), the lungs (pulmonary edema and cough and hemoptysis), damage to the recurrent larygneal nerve (horseness of the voice).
38.
Case: You hear a murmur radiating to the carotid arteries in a 65 year old smoker. He has angina and dizziness/syncope on doing gymnastics, and weak pulses on extremities. What is the MOA? What is the heart disease?
A) This is AORTIC STENOSIS. This results in left ventricular hypertrophy...as the heart must push against more resistance out of the heart. As a result, we see angina (due to lessened coronary artery refill), syncope because his exercise demands more oxygen and because the stenosis lessens the flow, and weak pulses for the same reason.
39.
Q) Quick, are you retaining? I repeat the angina case presentation with aortic stenosis. Quickly, what does the sound-pressure vs. time graph between S1 and S2 look like?
A) Remember the diamond shaped ejection murmur...
40.
Q) You see another diagram of ONLY the "rectangle shaped" sound/pressure vs. time graph between S1 and S2. This you recall is MITRAL REGURG. What is the MOST COMMON CAUSE of this dx?
A) Rheumatic fever from Group A beta hemolytic strep. Is this bug bacitracin sensitive??? Yes, it is.
41.
Q) Are Strep viridans partially or completely clear on hemolysis on blood agar? Are they susceptible to optochin?
A) They are alpha hemolytic (partially clear)...not beta hemolytic (which is completely clear). They are NOT susceptible to optochin.
42.
A patient presents with tertiary syphillis. You are shown a sound/pressure vs time graph where there is a decresendo after S2 (a wedge or triangle with a negative slop). What dx and MOA of the heart disease is this?
A) This is commonly caused when the aortic valve closes INSUFFICIENTLY. The subsequent REGURG causes the syphillitic aortic aneurysm.
43.
A guy named Big MAC is very tall and has a heart defect from a chromosomal anomaly. He has Marfan's syndrome.. What other TWO common illnesses can cause this aortic valve insufficiency? (hint: M=Marfan's, A=?, C=?)
A) A=ankylosing spondylitis, and C=coarctation of the aorta.
44.
Q) T or F: Release of CCK results in contraction of the Sphincter of Oddi.
F) It results in its RELAXATION. It is the gallbladder that contracts.
45.
Q) True or False: CCK release will cause the secretin potentiation to release enzymes and BICARBONATE from the PANCREAS.
A) True.
46.
T or F: CCK is released by the presence of carbohydrates into the colon.
A) False, CCK is released by the presence of FATS and protein into the DUODENUM.
47.
T or F: CCK has no effect on the rate of gastric emptying.
A) False, CCK SLOWS the rate of gastric emptying by constricting the pyloric sphincter.
48.
Case: you are pimped by the cardiology attending and shown a graph of the Jugular Venous Pulse with three peaks (a, c, v). What heart sound (S1, S2, S3, S4) does peak v represent. What is happening physiologically?
A) S3, The increased JVP is caused by the blood pressure against the closed tricuspid valve.
49.
Q) Same as the previous concept...what does peak c stand for in the JVP graph? When does it occur?
A) c=Right ventricular contraction, as the tricuspid valve pushes back into the atrium. Occurs right AFTER S1, when the mitral valve closes and the aortic valve opens.
50.
Q) Which aortic pressure is HIGHER as measured the the left ventricle, the exact point when the aortic valve opens OR when the aortic value closes? When?
A) Surprise...! It occurs at S2, when the aortic valve closes!
Guest-Ousaman Jah
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Guest-Ousaman Jah
Environmental Sanitation- Community Medicine
~6.3 mins read
Community Medicine
Theme: Environmental sanitation
CONTENTS:
1. Diseases associated with water suply.
2. Type of water. Advantages and disadvantages.
3. Water sources. Its protection.
4. Sources of water contamination.
5. Water sterilization.
INTRODUCTION
WHO estimates that 40 % of people do not have access to basic sanitation ( that is 2.6 billion people of whom 1.5 billion live in China and India). It is also estimated that 20 % of world wide population do not have access to clean water.
Every day 3 900 children die as a direct result of unsafe water or absence of basic sanitation.
Water-washed diseases ( lack of water for personal hygiene)
· Diarrheal diseases.
· Skin diseases ( including scabies)
· Eye diseases ( including trachoma)
Water-borne diseases ( Carry organism of specific diseases)
· Typhoid fever.
· Cholera.
· Poliomyelitis.
· Amoebiasis.
· Hepatitis A,E
Water-related diseases ( water is necessary in the life cycle of a disease vector)
· Malaria.
· Schistosomiasis ( bilharzia)
· Onchocerciasis ( River blindness )
· Draculosis ( guinea worm )
· Trypanosomiasis ( sleeping sickness)
The water-washed diseases are diseases preventable by washing transsmitted by:
1. Faecal-oral route due to lack of washing hands, eating utensils and vegetables.
2. Lack of personal hygiene( washing the face eye and body )
The water-borne diseases are due to dirty water containing the disease organisms themselves.
Type of water
1. Rain water.
Advantages:
· If collected from iron sheets or tile roofs into gutters and then clean, closed tanks, this is normally the purest natural water.
Disadvantages:
· It is very difficult to collect from thatched roofs.
· Gutters and large tanks are required to store sufficient rain water to last into the dry season.
· The water is “soft” and does not contain any essential mineral salts. It may not taste very good.
2. Water that falls on high hills ( upland surface water)
Advantages:
· The water that collects into streams above where people live is often plentiful and clean and makes very good drinking water.
· If it can be piped to people living lower down the hills, the water comes by gravity and no pumping is required.
Disadvantages:
· The source must be protected . If animal grazing or human settlement occurs in the catchment area, the water will be polluted.
3. Water in all other areas ( such as plains and the coastal belt)
A. Surface water.
Advantages:
· Surface water , whether in ponds, lakes, shallow springs, streams or rivers, or in water holes, shallow wells or dams, is the commonest source of water for most people.
· It is easily accessible, It can be obtained by hands or by simple pumps, and the larger lakes and rivers are permenent all the year round.
Disadvantages:
· This water is frecuently and easily polluted as it runs over the ground where humans and animals urinate and defecate, people also wash and bathe in it . It may be, as well, be polluted by chemicals used in agriculture or industry.
B. Underground water.
Advantages:
· It is usually clean and often plentiful and permanent.
· It may come from a long way away and it not so dependent on local rain .
· Many rural areas and small towns use this type of water.
Disadvantages:
· Water from deep wells and deep springs has usually dissolved a lot of salts and others minerals, making the water salty.
· This water generally needs pumping from great depths, often to tanks or reservoirs before reaching the user.
C. Sea water.
Sources of water.
1. Springs.
How to make it safer?
· By erecting a fence with a gate around the spring area to keep out animals.
· By building a ditch to allow water to drain away.
· By building a stone wall or box around the springs itself, through which a pipe is led.
2. Wells and boreholes. ( step wells, open wells, tubewells )
Well water can be made safer by:
· Fixing a removable cover.
· Building an outward-sloping apron wall around the well , 0.5-1 meter high. The wall prevents dirty water from running into the well and acts as a shelf where waterpots can be placed.
· Building a concrete drainage channel around the outside of the wall.
· Providing one container to draw water. ( this container with is fixed rope is allowed to rest only on the apron wall, never on the ground.
· Ensuring that no one use the well for washing.
· Encouraging the community to set up its own system for keeping the surrounds clean , repairing the well each year, keeping the handpump in good repair and chlorinating the well at regular intervals.
3. Ponds and watering holes. ( water from this sources is dangerous and can spread a variety of diseases, it should not be use for drinking, unless there is not other supply available but:
· It should be boiled or sterilized before drinking.
· Any pond used as a water supply or for washing should not be used for washing or watering animals.
4. Rivers and streams
Warning:
· Water should be collected from the river above the village , preferably through a sand filter , infiltration gallery or , in the case of hill communities, a gravity flow system.
· Bathing, washing and the watering of animals take place only below the village .
5. Water from standpipes or other piped systems.
Water coming from a tap is not always clean . It may come from a dirty source or become contaminated in the pipes.
Tap water can be made safer by:
· Checking the source is not dirty or contaminated.
· Checking the pipes to make sure there are not leaks or joins where germs can enter.
· Keeping the surrounds of a standpipe ( standpost) clean and well drained.
· Building a concrete or wooden platform on which to rest buckets.
· Constructing a fence to keep away animals.
· Encouraging the community to set up a system for checking source, pipes , tap and surround and keeping them clean and in good repair.
6. Rainwater tanks.
It can be made safer by:
· Cleaning the tank and entrance pipe before the rainy season.
· Placing a filter or screen where the water enters the tank to keep out insects, leaves and other dirt.
· Placing a sealed cover over the tank to keep the water clean and prevent mosquitoes from breeding
· Ensuring that taps alone are used for withdrawing water.
· Allowing the first heavy rainfall of the season to run through being used
· Chlorination.
Source of water contamination.
· The collecting surfaces for rain water may have leaves, insects or bird and animal faeces on them.
· When water runs over the earth, it may become contaminated with human or animal excreta,refuse, fertilizers or industrial waste.
· Shallow wells may be contaminated by excreta and refuse being washed into them, specially if latrines are nearby
· Rivers , lakes or dams may be contaminated by bathing or urinating or defecating in the water.
· Wells may also be contaminated by the use of dirty containers for drawing water , or by oil from a pump.
· Even piped water may become contaminated from leaks in the pipes, especially when this pass near foul water or dirty drains.
· Water may go bad if it is stored for too long in a pot or cistern.
· Water from any source may become contaminated if it is drunk from dirty or communal drinking vesssels.
Testing water
When new water supplies are being developed on a large scale, the quality of the water should be tested . The two main methods are:
1. Bacteriological analysis.
2. Chemical analysis.
For bacteriological analysis, water is collected in a sterile 500 ml flask. It must be kept cold (between 4 and 10 oC ) and analysis within 30 hours.
For chemical analysis, 4 or 5 litres are collected in any clean container. Examination for cyanide and pesticides should be done within 24 hour; for fluorides within a week.
Water sterilisation
1. The three pot method.
2. Filtration.
3. Disinfection with chlorine or bleach is highly effective.
4. Boiling ( It is the most effective way of killing germs)
5. Exposure to sun.
6. New technologies
· Water treatment system.
· Pur water purifier.
References:
· Community Health programme, page 305-322.
· Community Health, second edition, page 170-190.
Theme: Environmental sanitation
CONTENTS:
1. Diseases associated with water suply.
2. Type of water. Advantages and disadvantages.
3. Water sources. Its protection.
4. Sources of water contamination.
5. Water sterilization.
INTRODUCTION
WHO estimates that 40 % of people do not have access to basic sanitation ( that is 2.6 billion people of whom 1.5 billion live in China and India). It is also estimated that 20 % of world wide population do not have access to clean water.
Every day 3 900 children die as a direct result of unsafe water or absence of basic sanitation.
Water-washed diseases ( lack of water for personal hygiene)
· Diarrheal diseases.
· Skin diseases ( including scabies)
· Eye diseases ( including trachoma)
Water-borne diseases ( Carry organism of specific diseases)
· Typhoid fever.
· Cholera.
· Poliomyelitis.
· Amoebiasis.
· Hepatitis A,E
Water-related diseases ( water is necessary in the life cycle of a disease vector)
· Malaria.
· Schistosomiasis ( bilharzia)
· Onchocerciasis ( River blindness )
· Draculosis ( guinea worm )
· Trypanosomiasis ( sleeping sickness)
The water-washed diseases are diseases preventable by washing transsmitted by:
1. Faecal-oral route due to lack of washing hands, eating utensils and vegetables.
2. Lack of personal hygiene( washing the face eye and body )
The water-borne diseases are due to dirty water containing the disease organisms themselves.
Type of water
1. Rain water.
Advantages:
· If collected from iron sheets or tile roofs into gutters and then clean, closed tanks, this is normally the purest natural water.
Disadvantages:
· It is very difficult to collect from thatched roofs.
· Gutters and large tanks are required to store sufficient rain water to last into the dry season.
· The water is “soft” and does not contain any essential mineral salts. It may not taste very good.
2. Water that falls on high hills ( upland surface water)
Advantages:
· The water that collects into streams above where people live is often plentiful and clean and makes very good drinking water.
· If it can be piped to people living lower down the hills, the water comes by gravity and no pumping is required.
Disadvantages:
· The source must be protected . If animal grazing or human settlement occurs in the catchment area, the water will be polluted.
3. Water in all other areas ( such as plains and the coastal belt)
A. Surface water.
Advantages:
· Surface water , whether in ponds, lakes, shallow springs, streams or rivers, or in water holes, shallow wells or dams, is the commonest source of water for most people.
· It is easily accessible, It can be obtained by hands or by simple pumps, and the larger lakes and rivers are permenent all the year round.
Disadvantages:
· This water is frecuently and easily polluted as it runs over the ground where humans and animals urinate and defecate, people also wash and bathe in it . It may be, as well, be polluted by chemicals used in agriculture or industry.
B. Underground water.
Advantages:
· It is usually clean and often plentiful and permanent.
· It may come from a long way away and it not so dependent on local rain .
· Many rural areas and small towns use this type of water.
Disadvantages:
· Water from deep wells and deep springs has usually dissolved a lot of salts and others minerals, making the water salty.
· This water generally needs pumping from great depths, often to tanks or reservoirs before reaching the user.
C. Sea water.
Sources of water.
1. Springs.
How to make it safer?
· By erecting a fence with a gate around the spring area to keep out animals.
· By building a ditch to allow water to drain away.
· By building a stone wall or box around the springs itself, through which a pipe is led.
2. Wells and boreholes. ( step wells, open wells, tubewells )
Well water can be made safer by:
· Fixing a removable cover.
· Building an outward-sloping apron wall around the well , 0.5-1 meter high. The wall prevents dirty water from running into the well and acts as a shelf where waterpots can be placed.
· Building a concrete drainage channel around the outside of the wall.
· Providing one container to draw water. ( this container with is fixed rope is allowed to rest only on the apron wall, never on the ground.
· Ensuring that no one use the well for washing.
· Encouraging the community to set up its own system for keeping the surrounds clean , repairing the well each year, keeping the handpump in good repair and chlorinating the well at regular intervals.
3. Ponds and watering holes. ( water from this sources is dangerous and can spread a variety of diseases, it should not be use for drinking, unless there is not other supply available but:
· It should be boiled or sterilized before drinking.
· Any pond used as a water supply or for washing should not be used for washing or watering animals.
4. Rivers and streams
Warning:
· Water should be collected from the river above the village , preferably through a sand filter , infiltration gallery or , in the case of hill communities, a gravity flow system.
· Bathing, washing and the watering of animals take place only below the village .
5. Water from standpipes or other piped systems.
Water coming from a tap is not always clean . It may come from a dirty source or become contaminated in the pipes.
Tap water can be made safer by:
· Checking the source is not dirty or contaminated.
· Checking the pipes to make sure there are not leaks or joins where germs can enter.
· Keeping the surrounds of a standpipe ( standpost) clean and well drained.
· Building a concrete or wooden platform on which to rest buckets.
· Constructing a fence to keep away animals.
· Encouraging the community to set up a system for checking source, pipes , tap and surround and keeping them clean and in good repair.
6. Rainwater tanks.
It can be made safer by:
· Cleaning the tank and entrance pipe before the rainy season.
· Placing a filter or screen where the water enters the tank to keep out insects, leaves and other dirt.
· Placing a sealed cover over the tank to keep the water clean and prevent mosquitoes from breeding
· Ensuring that taps alone are used for withdrawing water.
· Allowing the first heavy rainfall of the season to run through being used
· Chlorination.
Source of water contamination.
· The collecting surfaces for rain water may have leaves, insects or bird and animal faeces on them.
· When water runs over the earth, it may become contaminated with human or animal excreta,refuse, fertilizers or industrial waste.
· Shallow wells may be contaminated by excreta and refuse being washed into them, specially if latrines are nearby
· Rivers , lakes or dams may be contaminated by bathing or urinating or defecating in the water.
· Wells may also be contaminated by the use of dirty containers for drawing water , or by oil from a pump.
· Even piped water may become contaminated from leaks in the pipes, especially when this pass near foul water or dirty drains.
· Water may go bad if it is stored for too long in a pot or cistern.
· Water from any source may become contaminated if it is drunk from dirty or communal drinking vesssels.
Testing water
When new water supplies are being developed on a large scale, the quality of the water should be tested . The two main methods are:
1. Bacteriological analysis.
2. Chemical analysis.
For bacteriological analysis, water is collected in a sterile 500 ml flask. It must be kept cold (between 4 and 10 oC ) and analysis within 30 hours.
For chemical analysis, 4 or 5 litres are collected in any clean container. Examination for cyanide and pesticides should be done within 24 hour; for fluorides within a week.
Water sterilisation
1. The three pot method.
2. Filtration.
3. Disinfection with chlorine or bleach is highly effective.
4. Boiling ( It is the most effective way of killing germs)
5. Exposure to sun.
6. New technologies
· Water treatment system.
· Pur water purifier.
References:
· Community Health programme, page 305-322.
· Community Health, second edition, page 170-190.
Adesuwa
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Adesuwa
Malaria
~0.9 mins read
Malaria is cause by infection with sporozoa of the genus plasmodium, transmitted in nature by the bite of female mosquito.four species of plasmodium are responsible for many infection.
Plasma falciparus
Plasmodium ovale
Plasmodium vivax
Plasmodium malaria
In Nigeria over three quarters of malaria infection are cause by p.falciparum.p.malariae.p.ovale.p.vivaare practically.absent in West Africa.
The absent of vivax malaria in West Africa can be explained by the non existent of Duffy blood in the population. Duffy antigen act receptor for p vivax, making it possible for the parasite to penetrate the red blood cells.
All form of human malaria are transmitted in nature by the bite of Anopheles mosquito, but rarely artificial infection can be results from transfusion of blood containing erythrocytic phase of the parasite or vary rarely from mother to child through.placents.
The major vector of human malaria are Anopheles gambiiae.Anophele arabiense are most dominant in the savañnah area and cities while gambiae are highly dense in forest of the tropics.Anophenes funestun have an uneven distribution and the salt water forms, Anopheles mealas are essentially coastal species.The mosquito become infected by injecting human blood containing make and female gametocytes.
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