User:Meninggococcemia

Beware of food-borne diseases this summer By EDUARDO GONZALES, MD March 30, 2009, 12:16pm Q. Is it true that food-borne diseases are more common during summer? If so, why? Can you enumerate these diseases? How can we prevent them? -- Myrna M., Los Banos, Laguna

A. Yes, the incidence of food-borne diseases peaks during summer. This is primarily because most food-borne pathogens (i.e., disease-causing microorganisms) grow fastest in warm and humid weather. Furthermore, people do more cooking and eating outdoors (i.e., picnics, barbecues, campings) during summer, which means they do without the safety facilities that their houses provide such as refrigeration and proper washing.

The list of diseases caused by pathogens or their toxins (poisons) that are transmitted through the intake of contaminated food and water is a long one. Most of these diseases affect the gastro-intestinal tract, but some affect other organs, too. Food-borne pathogens include viruses such as the hepatitis A virus; bacteria such as those that cause food poisoning and various forms of gastroenteritis, cholera, typhoid fever and botulism; protozoa such as E. histolytica, the causative agent of amebiasis; and, other parasites such as ascaris, other roundworms and tapeworms.

Any food item can be contaminated by pathogens and toxins. The contamination can occur during production, processing, distribution, preparation or storage of food.

Contamination of food with disease-causing agents can occur in the farm. For example, tapeworms which humans acquire when they eat raw or half-cooked meat find their way into pork or beef when cattle and pigs ingest the eggs of these worms while grazing. Another example, amoeba and the hepatitis A virus contaminate vegetables if plants are fertilized with night soil or watered with water from sewage canals (two common practices in the Philippines).

Food processing plants that do not comply with standard health safety procedures are also occasional sources of pathogens in food products. But very often, food-borne illnesses are caused by improper handling and preparation of food at home.

Food-borne diseases, without exception, are preventable. Most can be prevented by simply observing the following measures:

Buy and consume only food (either raw or processed) that complies with safety standards.
Cook food thoroughly. In particular, meat should not be eaten raw.
Thoroughly wash with flowing water fruits and vegetables that are to be eaten raw. This will not totally eliminate pathogens, but their number can be significantly reduced for the body’s other defenses to take care of.
Wash food items for cooking before chopping or cutting.
Wash with soap and water all utensils, chopping boards and kitchen areas before preparing meals.
Wash hands thoroughly with soap and water before preparing, eating and handling food.
Eat cooked food within 1-2 hours after cooking.
Refrigerate leftovers within 1-2 hours.
Re-heat leftovers thoroughly before eating.
Do not allow contact or mixing of raw and cooked foods.
Protect food from rodents, cockroaches, flies and other insects.
Consume milk only if it has been pasteurized.
Ensure that your drinking water is safe.
When going for outings, keep perishable food like cooked meats, potato salads, etc. in an insulated cooler that is packed with ice. Do the same for raw meat, poultry and vegetables, but in a separate cooler.

Rheumatic fever is an inflammatory disease that may develop two to three weeks after a Group A streptococcal infection (such as strep throat or scarlet fever). It is believed to be caused by antibody cross-reactivity and can involve the heart, joints, skin, and brain[1]. Acute rheumatic fever commonly appears in children between ages 5 and 15, with only 20% of first time attacks occurring in adults[1].

It gets its name for its similarity in presentation to rheumatism.[2]

[edit] Diagnosis

Rheumatic heart disease at autopsy with characteristic findings (thickened mitral valve, thickened chordae tendineae, hypertrophied left ventricular myocardium).Modified Jones criteria were first published in 1944 by T. Duckett Jones, MD.[3] They have been periodically revised by the American Heart Association in collaboration with other groups.[4] According to revised Jones criteria, the diagnosis of rheumatic fever can be made when two of the major criteria, or one major criterion plus two minor criteria, are present along with evidence of streptococcal infection. Exceptions are chorea and indolent carditis, each of which by itself can indicate rheumatic fever. [5][6][7]

[edit] Major criteria Migratory polyarthritis: a temporary migrating inflammation of the large joints, usually starting in the legs and migrating upwards. Carditis: inflammation of the heart muscle which can manifest as congestive heart failure with shortness of breath, pericarditis with a rub, or a new heart murmur. Subcutaneous nodules: painless, firm collections of collagen fibers over bones or tendons. They commonly appear on the back of the wrist, the outside elbow, and the front of the knees. Erythema marginatum: a long lasting rash that begins on the trunk or arms as macules and spreads outward to form a snake like ring while clearing in the middle. This rash never starts on the face and it is made worse with heat. Sydenham's chorea (St. Vitus' dance): a characteristic series of rapid movements without purpose of the face and arms. This can occur very late in the disease. [edit] Minor criteria Fever Arthralgia: Joint pain without swelling Raised Erythrocyte sedimentation rate or C reactive protein Leukocytosis ECG showing features of heart block, such as a prolonged PR interval[8] Supporting evidence of Streptococcal infection: elevated or rising Antistreptolysin O titre or DNAase.[1]. Previous episode of rheumatic fever or inactive heart disease [edit] Other signs and symptoms Abdominal pain Nose bleeds [edit] Pathophysiology Rheumatic fever is a systemic disease affecting the peri-arteriolar connective tissue and can occur after an untreated Group A Beta hemolytic streptococcal pharyngeal infection. It is believed to be caused by antibody cross-reactivity. This cross-reactivity is a Type II hypersensitivity reaction and is termed molecular mimicry. Usually, self reactive B cells remain anergic in the periphery without T cell co-stimulation. During a Strep. infection, mature antigen presenting cells such as B cells present the bacterial antigen to CD4-T cells which differentiate into helper T2 cells. Helper T2 cells subsequently activate the B cells to become plasma cells and induce the production of antibodies against the cell wall of Streptococcus. However the antibodies may also react against the myocardium and joints[9], producing the symptoms of rheumatic fever.

Group A streptococcus pyogenes has a cell wall composed of branched polymers which sometimes contain "M proteins" that are highly antigenic. The antibodies which the immune system generates against the "M proteins" may cross react with cardiac myofiber protein myosin[10],heart muscle glycogen and smooth muscle cells of arteries, inducing cytokine release and tissue destruction. However, the only proven cross reaction is with perivascular connective tissue.[citation needed] This inflammation occurs through direct attachment of complement and Fc receptor-mediated recruitment of neutrophils and macrophages. Characteristic Aschoff bodies, composed of swollen eosinophilic collagen surrounded by lymphocytes and macrophages can be seen on light microscopy. The larger macrophages may become Aschoff giant cells. Acute rheumatic valvular lesions may also involve a cell-mediated immunity reaction as these lesions predominantly contain T-helper cells and macrophages.[11]

In acute RF, these lesions can be found in any layer of the heart and is hence called pancarditis. The inflammation may cause a serofibrinous pericardial exudates described as “bread-and-butter” pericarditis, which usually resolves without sequelae. Involvement of the endocardium typically results in fibrinoid necrosis and verrucae formation along the lines of closure of the left-sided heart valves. Warty projections arise from the deposition, while subendothelial lesions may induce irregular thickenings called MacCallum plaques.

Chronic rheumatic heart disease is characterized by repeated inflammation with fibrinous resolution. The cardinal anatomic changes of the valve include leaflet thickening, commissural fusion and shortening and thickening of the tendinous cords. [11]

[edit] Treatment The management of acute rheumatic fever is geared toward the reduction of inflammation with anti-inflammatory medications such as aspirin or corticosteroids. Individuals with positive cultures for strep throat should also be treated with antibiotics. Aspirin is the drug of choice and should be given at high doses of 100 mg/kg/day. One should watch for side effects like gastritis, salicylate poisoning etc. Steroids are reserved for cases where there is evidence of involvement of heart. The use of steroids may prevent further scarring of tissue and may prevent development of sequelae such as Mitral stenosis. Monthly injections of Longacting Penicillin must be given for a period of 5 years in patients having one attack of Rheumatic fever. If there is evidence of carditis, the length of Penidure therapy may be up to 40 years. Another important cornerstone in treating rheumatic fever includes the continual use of low dose antibiotics (such as penicillin, sulfadiazine, or erythromycin) to prevent recurrence.

[edit] Infection Patients with positive cultures for Streptococcus pyogenes should be treated with penicillin as long as allergy is not present. This treatment will not alter the course of the acute disease.

[edit] Inflammation Patients with significant symptoms may require corticosteroids. Salicylates are useful for pain.

[edit] Heart failure Some patients develop significant carditis which manifests as congestive heart failure. This requires the usual treatment for heart failure: diuretics and digoxin. Unlike normal heart failure, rheumatic heart failure responds well to corticosteroids.

[edit] Prevention Prevention of recurrence is achieved by eradicating the acute infection and prophylaxis with antibiotics. The American Heart Association recommends daily or monthly prophylaxis continue long-term, perhaps for life.[12]

Screening school-aged children for sore throats also aid in prevention.

[edit] Epidemiology

Disability-adjusted life year for rheumatic heart disease per 100,000 inhabitants in 2004.[13]

    no data

    less than 20

    20-40

    40-60

    60-80

    80-100

    100-120

    120-140

    140-160

    160-180

    180-200

    200-330

    more than 330Rheumatic fever is common worldwide and responsible for many cases of damaged heart valves. In Western countries, it became fairly rare since the 1960s, probably due to widespread use of antibiotics to treat streptococcus infections. While it is far less common in the United States since the beginning of the 20th century, there have been a few outbreaks since the 1980s. Although the disease seldom occurs, it is serious and has a mortality of 2–5%.[14]

Rheumatic fever primarily affects children between ages 5 and 15 years and occurs approximately 20 days after strep throat or scarlet fever. In up to a third of cases, the underlying strep infection may not have caused any symptoms.

The rate of development of rheumatic fever in individuals with untreated strep infection is estimated to be 3%. The incidence of recurrence with a subsequent untreated infection is substantially greater (about 50%).[15] The rate of development is far lower in individuals who have received antibiotic treatment. Persons who have suffered a case of rheumatic fever have a tendency to develop flare-ups with repeated strep infections.

The recurrence of rheumatic fever is relatively common in the absence of maintenance of low dose antibiotics, especially during the first three to five years after the first episode. Heart complications may be long-term and severe, particularly if valves are involved.

Survivors of Rheumatic fever often have to take penicillin to prevent streptococcal infection which could possibly lead to another case of Rheumatic fever that could prove fatal.