Tuberculosis verrucosa cutis

Tuberculosis (TB), known in ye olde days as consumption or the white plague, is an infectious disease caused by bacteria belonging to the genus Mycobacterium. The most common agent of disease is, appropriately, Mycobacterium tuberculosis. TB can take many forms, but the lungs are almost always involved. The trademark symptom of an active pulmonary TB infection is coughing up blood. Gross.

The overwhelming majority (~90%) of people infected with TB bacteria remain asymptomatic and do not spread the disease. This is referred to passive, as opposed to active, TB. Infections can be acquired by breathing in airborne bacteria or being exposed to body fluids from actively infected individuals. TB is one of the few bacteria that can remain airborne and viable for long periods of time. It gets into the air when people with active pulmonary TB cough, sneeze, spit, or do anything else that renders the gooey stuff lining their respiratory tract into the air.

Tuberculosis verrucosa cutis (TVC) is a type of cutaneous (skin-presenting) TB. It occurs in individuals who have been previously infected with TB (and have a passive infection) but then are reinfected via the skin. TVC usually first shows itself as a solitary wart-like thing that is often mistaken for simply being a common wart (verruca vulgaris). However, with time, the wart slowly extends at its periphery and develops into a ringed red-brown plaque. The ring is the result of the centre part healing while expansion continues at the periphery, and is occasionally mistaken for a fungal infection. Sometimes the plaque develops fissures from which pus and scab-like stuff oozes out. Good times!

TVC lesions most commonly occur on the hands, with the bacteria generally getting into the skin via a puncture or other wound, and have historically been associated with professions that would likely involve exposure to TB. Physicians, pathologists, and laboratory workers may be exposed directly to people with active infections. Thus has arisen the following common names for TVC: anatomists' wart, prosectors' wart, and verruca necrogenica (Latin for 'generated by corpses'). Farmers, butchers, and vets may be exposed to cattle infected with Mycobacterium bovis.

TVC is treated with a cocktail of antituberculous drugs.

Metal fume fever

As obvious as they come, metal fume fever (MFF) is an illness with a symptomatology that includes fever, that is caused by the inhalation of metal oxide fumes. A fume is a particular type of aerosol that consists of very fine particles of oxidized metal produced when a metal is heated to sufficiently high enough temperatures that a bit of it vapourizes and rises into the air. Once in the air, the gaseous metal rapidly cools and transitions from gas to liquid to solid, forming tiny little bits of metal that are small enough to hang out in the air for a while. Because these particles are so small, they are able to penetrate down into the gas exchange region of the human respiratory tract, where they are thought to negatively interact with the immune system to cause symptoms.

MFF goes by a number of aliases including: brass founders ague, zinc shakes, and Monday morning fever. Common symptoms of MFF include the eponymous fever, headache, myalgia (muscle pain), fatigue, and dyspnoea (breathing difficulties). As these symptoms resemble those of the flu, it is likely that many cases of MFF go unrecognized. Onset is usually rapid, within 3-10 hours following exposure to metal fumes. Spontaneous recovery typically occurs within 24 hours. Because of the nature of the illness, workers often experience the worst symptoms after a period of time away from work (and thus exposure to fumes), giving rise to the term 'Monday morning fever'. Exposure to metal fumes can also result in chemical pneumonitis (inflammation of the lung), which in its early stages may resemble MFF but progresses to a more severe illness and may be complicated by pulmonary edema (accumulation of fluid in the lungs).

Metal oxides that have been associated with MMF include those of zinc, magnesium, copper, and cadmium. Zinc oxide is by far the most common cause, with sources of exposure including welding galvanized steel or brass, hot-dip galvanizing, and metal pouring in brass foundries.

Kaye P, Young H, O'Sullivan I. Metal fume fever: a case report and review of the literature. Emerg Med J. 2002 May;19(3):268-9.

Byssinosis

Cotton is a soft fibre that surrounds the seeds of the cotton plant (genus Gossypium) and can be spun into yarn or thread and used to make a variety of textile products (denim, chambray, corduroy, twill, etc.).

During the manufacture of cotton yarn and fabric, a dust containing cotton particles may be generated. If workers are not adequately protected from exposure to cotton dust by control measures such as ventilation and respirators, they may develop an occupational lung disease called byssinosis, or "brown lung". This disease was common among workers in cotton mills during the industrial revolution. Byssinosis is also caused by breathing in dusts generated from other plant fibres, including flax, hemp, or sisal in the workplace.

With byssinosis, the cotton/flax/hemp/sisal particles of concern are those small enough to get from the mouth/nose to the upper part of the lungs (i.e. the trachea, bronchi, and bronchioles) but large enough that they do not penetrate further down into the alveolar (gas exchange) region of the lung).

Exposure to cotton/flax/hemp/sisal dust can lead to an asthma-like narrowing of the airways, the symptoms of which (chest tightness, cough, wheezing) usually dissipate at the end of the work week. Long term exposure to the dust can lead to a chronic lung disease where the symptoms persist and lung function is damaged. Byssinosis can be fatal, usually due to infection or respiratory failure.

Asbestosis, Lung Cancer, and Mesothelioma

Asbestos refers to a group of fibrous minerals that are used to make fireproof items and to cover and so render other materials fireproof. Originally hailed as a wonderful means of saving lives by protecting buildings against fire, it has ended up taking the lives of many of those who were exposed to it.

The inhalation of asbestos fibres can cause a number of serious and usually fatal illnesses, including asbestosis, lung cancer, and mesothelioma. The recognition of the hazards posed by inhalational exposure to asbestos has led many countries to the ban certain uses of the minerals and establish laws regarding the remediation of asbestos-containing buildings.