Prevalence and Incidence of Common cold

Prevalence/Incidence of Common cold: Online Medical Books

16 MEDICAL BOOKS ONLINE! Review excerpts from medical books online, free, without registration, for more information about the prevalence and/or incidence of Common cold.

Common cold: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

About 90% of colds stem from a viral infection of the upper respiratory passages and consequent mucous membrane inflammation; occasionally, colds result from a mycoplasmal infection. (See What happens in the common cold.)

Over a hundred viruses can cause the common cold. Major offenders include rhinoviruses, coronaviruses, myxoviruses, adenoviruses, coxsackieviruses, and echo-viruses.

Transmission occurs through airborne respiratory droplets, contact with contaminated objects, and hand-to-hand transmission. Children acquire new strains from their schoolmates and pass them on to family members. Fatigue or drafts don't increase susceptibility.

The common cold is more prevalent in children than in adults; in adolescent boys than in girls; and in women than in men. In temperate zones, it's more common in the colder months; in the tropics, during the rainy season.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Cold injuries: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Localized cold injuries occur when ice crystals form in the tissues and expand extracellular spaces. With compression of the tissue cell, the cell membrane ruptures, interrupting enzymatic and metabolic activities. Increased capillary permeability accompanies histamine release, resulting in aggregation of red blood cells and microvascular occlusion. Hypothermia effects chemical changes that slow the functions of most major organ systems, such as decreased renal blood flow and decreased glomerular filtration. Frostbite results from prolonged exposure to dry temperatures far below freezing; hypothermia, from near drowning in cold water and prolonged exposure to cold temperatures.

The risk of serious cold injuries, especially hypothermia, is increased by youth, old age, lack of insulating body fat, wet or inadequate clothing, drug abuse, cardiac disease, smoking, fatigue, hunger and depletion of caloric reserves, and excessive alcohol intake (which draws blood into capillaries and away from body organs).

ELDER TIP The following risk factors put elderly people at increased risk for cold injuries: cardiovascular disease, alcohol abuse, malnutrition, diabetes, skin diseases, scarring from major burns, inadequate fluid intake, working outdoors, wearing inappropriate clothing, and living in poor environmental conditions. The use of anticholinergics, phenothiazines, diuretics, antihistamines, antidepressants, or beta-adrenergic blockers also increases the risk.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Colorado tick fever: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Colorado tick fever is transmitted to humans by a hard-shelled wood tick called Dermacentor andersoni. The adult tick acquires the virus when it bites infected rodents and remains permanently infective.

Incidence is high in Colorado, where up to 15% of people who regularly camp show past exposure. It's much less common in the rest of the United States.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Lassa fever: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

A chronic infection in rodents, Lassa virus is transmitted to humans by contact with infected rodent urine, feces, and saliva. The virus enters the bloodstream, lymph vessels, and respiratory and digestive tracts. It then multiplies in the cells of the reticuloendothelial system. In the early stages of this illness, when the virus is in the throat, human transmission may occur through inhalation of infected droplets.

As many as 100 cases of Lassa fever occur annually in western Africa; the disease is rare in the United States.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Relapsing fever: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

The body louse (Pediculus humanus corporis) carries louse-borne relapsing fever (B. recurrentis), which typically occurs in epidemics during wars, famines, and mass migrations. Cold weather and crowded living conditions also favor the spread of body lice.

Inoculation takes place when the victim crushes the louse, causing its infected blood or body fluid to soak into the victim's bitten or abraded skin or mucous membranes.

Louse-borne relapsing fever is most common in North and Central Africa, Europe, Asia, and South America. No cases of louse-borne relapsing fever have been reported in the United States since 1900.

Tick-borne relapsing fever, however, is found in the United States and is caused by at least 15 Borrelia species; the three species most commonly identified with tick carriers are B. hermsii (associated with Ornithodoros hermsi), B. turicatae (associated with O. turicata), and B. parkeri (associated with O. parkeri). This form of the disease is most prevalent in Texas and other western states, usually during the summer when ticks and their hosts (chipmunks, goats, squirrels, rabbits, mice, rats, owls, lizards, and prairie dogs) are most active. In the colder weather, outbreaks sometimes afflict people such as campers who sleep in tick-infested cabins.

Because tick bites are virtually painless and most Ornithodoros ticks feed at night but don’t imbed themselves in the victim’s skin, many people are bitten unknowingly.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Rheumatic fever and rheumatic heart disease: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Rheumatic fever appears to be a hypersensitivity reaction to a group A beta-hemolytic streptococcal infection, in which antibodies manufactured to combat streptococci react and produce characteristic lesions at specific tissue sites, especially in the heart and joints. Because very few persons (3%) with streptococcal infections ever contract rheumatic fever, altered host resistance must be involved in its development or recurrence. Although rheumatic fever tends to be familial, this may merely reflect contributing environmental factors. For example, in lower socioeconomic groups, incidence is highest in children between ages 5 and 15, probably as a result of malnutrition and crowded living conditions. This disease strikes generally during cool, damp weather in the winter and early spring. In the United States, it’s most common in the northern states.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Rocky Mountain spotted fever: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

R. rickettsii is transmitted to a human or small animal by the prolonged bite (4 to 6 hours) of an adult tick — the wood tick (Dermacentor andersoni) in the west and by the dog tick (Dermacentor variabilis) in the east. Occasionally, it's acquired through inhalation (it can occur in laboratory settings where aerosolization of blood and specimens may occur) or through the contact of abraded skin with tick excreta or tissue juices. (This explains why people should'nt crush ticks between their fingers when removing them from other people and animals.) In most tick-infested areas, 1% to 5% of the ticks harbor R. rickettsii.

Endemic throughout the continental United States, RMSF is particularly prevalent in the southeast and southwest. Because RMSF is associated with outdoor activities, such as camping and backpacking, the incidence of this illness is usually higher in the spring and summer. Epidemiologic surveillance reports for RMSF indicate that the incidence is also higher in children ages 5 to 9, men and boys, and whites.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Whooping cough: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Whooping cough is usually transmitted by the direct inhalation of contaminated droplets from a patient in the acute stage; it may also be spread indirectly through soiled linen and other articles contaminated by respiratory secretions.

Whooping cough is endemic throughout the world, usually occurring in late winter and early spring. In about 50% of cases, it strikes unimmunized children younger than age 1, because the immunization series hasn’t been completed and the child has had contact with an adult harboring the organisms.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

About prevalence and incidence statistics:

The term 'prevalence' of Common cold usually refers to the estimated population of people who are managing Common cold at any given time. The term 'incidence' of Common cold refers to the annual diagnosis rate, or the number of new cases of Common cold diagnosed each year. Hence, these two statistics types can differ: a short-lived disease like flu can have high annual incidence but low prevalence, but a life-long disease like diabetes has a low annual incidence but high prevalence. For more information see about prevalence and incidence statistics.