Saturday, December 4, 2010

Learn about cholera

This lesson is about cholera since it is the news as being in Haiti.

Cholera is an acute infection of the gastrointestinal tract. It is caused by vibrio comma [V.cholerae] which is a gram negative, short,curved bacillus [bacteria] with a terminal flagellum. It is aerobic meaning it needs air to thrive, and is mobile,grows on ordinary culture mediums, and exists in favorable condtions for a few days but dies out in the bowel movement in 1-2 days. Cholera is acquired by ingestion [eating,swallowing] food or drink contaminated with feces which conatins the v.Chloerae bacteria. Which is why you should always wash your hands before eating,before handling food,after touching your shoes,or being in areas where feces might be on handles,seats,etc [public btahrooms, or in rural remote areas those places designated as 'outhouses',or outdoor bathrooms.
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History of disease

Cholera is always present in the lower Ganges River in India, because of the contaminated water of that river where animals and humans bathe [and probably defecate]. It spread to China in the 17th century. A number of pandemics [defined by WHO] occurred in the US during the 19th and 20th centuries but was practically eradicated at the seaports after 1873. During and after World War I, there were epidemics in Europe. Also during WWII there were epidemics in the "Far East" and "Near East' but at that time they did not reach the Americas or Europe.
Improved sanitation and enforcement of the International Sanitary Regulations has resulted in cholera being mostly in lower Ganges River now and in areas where flooding,and sanitation merged [sewers ran over, and cesspools did, and contaminated flooding with feces happened] .

Epidemiology

Subclinical disease may be present in some communities.Sub-clinical means that symptoms have not appeared yet. The most likely sources of the bacteria are those people in the incubation stage or with mild symptoms. Contaminated water is the most often method of the disease spreading. [Which is why if you are in areas where flooding occurred,or known cholera disease reported,or known fecal contamination
you shoud boil your water before drinking or bathing. Flies also spread the disease bacteria. The conditions which cause it to rapidly spread are high tempaerature, high relative humidity,and intermittent rains[monsoons,flooding]. It is possible for it to spread rapidly but everyone who comes into contact with it does not necessarily contract it.

Symptoms,signs,and morbid anatomy

It is characterized by diarrhea,vomiting,dehydration, which is severe in most cases. Striking changes to the person's appearance occur because of the extreme dehydration. After death of cholera-infected persons,the rigor mortis is unusually marked. Dryness and shrinkage of person's flesh/bulk is apparent everywhere. Inflammatory changes are not usually present. The person's blood is thick and scanty. The walls of the intestines are bluish looking and congested. The membranes look like
ground glass and are sticky. The lumen of the bowel contains gray opalescent liquid not feces.
Large areas of mucosa may be gone but ulceration is not present. The lymphoid tisse of the ileum may be prominent. The kidneys show marked congestion.

Pathology

The cholera vibrio is primarily found in the ileum,but may be also in small numbers in the lungs and other organs of the body. They are seldom found in the blood stream. The bacteria does not produce an exotoxin,but does produce a powerful endotoxin. The usual first effect of infection is loss of large amounts of fluid and salt as a result of profuse vomiting and diarrhea.
That affects the acid-base balance of the body. The extraction of massive amounts of fluid from the cells,tissues,spaces,in a short period of time,is rarely found in any other disease except infant diarrhea,and hemorrhage of blood. The blood quickly becomes concentrated with specific gravity of 1.070;20 gms hemoglobin per 100 cc of blood,and 75 for erythrocite volume percentage,and 7,000,000
per cu mm for erythrocyte count. The concentration of plasma proteins is also inreased,and the circulation of blood throughout the body is greatly effected. The blood pressure falls,and the cardiac output [blood pumped by heart] is much decreased [shock]. Because of these systemic problems,the
renal function is greatly compromised and impaired unto death. [When enough blood does not get to to the brain,heart and kidneys, the person dies.] The sodium lost from the infected bowel results in a shift of the acid-base balance of sodium and chloride and is accentuated by the acid which is
retained when the kidneys start failing. Values as low as 7.1 were noted in some people for pH,and 138 milliequivalents per liter for the total base in the blood. Urea and nitrogen are retained because of renal failure. If a person dies in the early stages of cholera it is usually because of dehydration.
But in the later stages death is usually from renal failure.
Having cholera and surviving it does not prevent another infection later i.e. it does not cause the person to build antibodies against it.

Incubation and physiology

The incubation period is 1-5 days, with sudden onset usually. It might be preceded by depression, malaise,and simple diarrhea. Cholera infection is manifested by volumes of watery stools,copious vomiting,and being unable to get up. The speed with which it becomes overwhelming to the body is striking. Stools are so frequent that soon lose any fecal content and start sloughing off the inside of the bowel, but no blood or pus is noted. The absence of tenesmus is often noted.
Vomiting may occur without nausea or retching [projectile and sudden]. Great thirst occurs but fluids or food are vomited up. The person becomes gaunt, and pinched looking with sunken eyes.
The skins becomes bluish [cyanotic] and shriveled. The voice becomes thick and feeble.
Marked tachycardia [fast racing pulse] occurs and pulse may be barely perceptible. The blood pressure may fall below 60 mm mercury for systolic. Urine may cease [a particularly important sign of approaching death] and uremia may result. The body temperature falls.

Diagnosing cholera

Patient history is very important. If the person lives in an area where cholera reported, or conditions ripe for it to flourish,it should be suspected in cases of extreme vomiting and diarrhea.
Other condtions which give similar symptoms are bacillary desentery, food poisoning,heat exhaustion,some forms of malaria, and other conditions associated with shock secondary to diarrhea. It is very important that the accurate diagnosis be made as quickly as possbile as the implications for the household and community are enormous when misdiagnosed.
The specific diagnosis is made by testing the stools passed, by agglutination of V cholerae. Cultures have be done on fresh stool, and examined under microscope for the bacillus.

Prognosis
The outcome depends on how quickly cholera was diagnosed and treated, and how good the person's health was before contracting cholera. The course of the disease averages 3-5 days but death could occur in hours, and after many days also. If not treated quickly, the mortality rate is about 60 percent. With quick and appropriate treatment,the death rate is about 5 percent.

Treatment

Strict Isolation of infected or exposed persons.
Boil clothing of infected persons and drinking,eating utensils.
Disinfect as for typhoid standards.
Keep person warm.
Give fliuds but usually cannot retain those by mouth,so give intravenously.
Do not give sedatives,pain medicines, because likely to mask or worsen situation.
Give electrolytes by IV and or by mouth when better.
Do not give blood or blood products [blood already concentrated].
Start physiological saline intravenously as soon as diagnosis is made-critical to survival of patient.
Dextrose 5 % solutions IV ar rate so as not to exceed 50 gm of dextrose per hour after saline.
Patients with cholera need rehydration faster than almost any other disease but it is possible to overload their circulatory system if too fast.
The best indicator of improvement is the specific
gravity of the blood. As as the specific gravity approaches its normal [1.056-1058] for the blood, IV fluids should be slowed.
As a general rule, two liters of Normal Saline are needed in first 2 hours,
and more afterwards at slower rate so that 4-8 liters is often required to bring blood viscosity to normal.
In some cases the loss of alkali will have to be replaced. The acidosis of cholera is different from the acidosis of diabetes or nephritis. Ketone is not present in cholera patients' urine. Alkali replacement may be IV sodium bicarbonate with 18 gm sodium bicarb and 6 gm sodium chloride to one liter of sterile distilled water. It is not unusual for cholera patients to need 500 cc of alkali replacement fluids
Also potassium and phosphate have to be replaced via IV.

Prevention
Handwashing after toileting,after handling shoes,after being in area known for cholera present,after touching sick person,or handling food trays/paltes.utensils.
Proper disposal of stool contaminated items used by infected patients .
Blood and body precautions for medical personnel.
Quarantine infected persons.
Eradicate flies.
Strict control of water supply,with boil water command for community issued at diagnosis first case.
Disposal of food touched by infected persons.
Do not allow eating of raw foods,[vegetables,fruits,cheeses,etc] when cholera in community.
Close supervision of food handlers to ensure proper hand-washing,and disposal.

Vaccination
There is a cholera vaccine and it is recommended for those traveling or living in places known to harbor cholera bacillus.


References used
A Textbook of Medicine by Cecil & Loeb, with all put into laymen's terminology and simple words
to avoid jargon and reach more people.

Gloria Poole,RN; 7:18 PM 12/4/2010;
licensed in Missouri, and resident of Missouri