Porphyria

The porphyrias are a group of inherited or acquired disorders of certain enzymes in the heme bio-synthetic pathway (also called porphyrin pathway). They manifest with either neurological complications ("acute") or skin problems ("cutaneous"), or occasionally both. The porphyrias may be classified by the primary site of the overproduction and accumulation of the porphyrins (or their chemical precursors) as hepatic porphyrias, where porphyrins are overproduced in the liver predominantly, or erythropoietic porphyrias, where the overproduction is confined to the bone marrow and the erythrocye (red blood cell) and its precursors.

The acute, or hepatic, porphyrias primarily affect the nervous system, resulting in abdominal pain, vomiting, acute neuropathy, muscle weakness, seizures, and mental disturbances, including hallucinations, depression, anxiety, and paranoia. Cardiac arrhythmias and tachycardia (high heart rate) may develop as the autonomic nervous system is affected. Pain can be severe and can, in some cases, be both acute and chronic in nature. Constipation is frequently present, as the nervous system of the gut is affected, but diarrhea can also occur.

Given the many presentations and the relatively low occurrence of porphyria, the patient may initially be suspected to have other, unrelated conditions. For instance, the polyneuropathy of acute porphyria may be mistaken for Guillain-Barré syndrome, and porphyria testing is commonly recommended in those situations.

The cutaneous, or erythropoietic, porphyrias primarily affect the skin, causing photosensitivity (photodermatitis), blisters, necrosis of the skin and gums, itching, and swelling, and increased hair growth on areas such as the forehead. Often there is no abdominal pain, distinguishing it from other porphyrias.

In some forms of porphyria, accumulated heme precursors excreted in the urine may cause various changes in color, after exposure to sunlight, to a dark reddish or dark brown color. Even a purple hue or red urine may be seen.

Often, empirical treatment is required if the diagnostic suspicion of a porphyria is high since acute attacks can be fatal. A high-carbohydrate diet is typically recommended; in severe attacks, a glucose 10% infusion is commenced, which may aid in recovery. Pain is severe, frequently out of proportion to physical signs and often requires the use of opiates to reduce it to tolerable levels. Pain should be treated as early as medically possible, due to its severity. Nausea can be severe; it may respond to phenothiazine drugs but is sometimes intractable. Hot water baths/showers may lessen nausea temporarily, though caution should be used to avoid burns or falls. Some liver diseases may cause porphyria even in the absence of genetic predisposition. These include hemochromatosis and hepatitis C. Treatment of iron overload may be required.

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Lyme disease

Lyme disease, sometimes referred to as Lyme infection, is a bacterial illness, transmitted to humans by the bite of deer ticks (Ixodes ticks) carrying a bacterium known as Borrelia burgdorferi. The disease has been reported in the Northeast, Mid-Atlantic, North Central, and Pacific coastal regions of the United States and in Europe, where it was first described almost 100 years ago. Lyme disease can affect the skin, joints, heart and the nervous system. It occurs in phases - the early phase beginning at the site of the tick bite with an expanding ring of redness, being diagnosed on the patient's clinical signs of illness and the detection of Lyme antibodies in the blood.

Lyme disease can affect multiple body systems and produce a range of symptoms. Not all patients with Lyme disease will have all symptoms and many of the symptoms are not specific to Lyme disease, but can occur with other diseases as well. The incubation period from infection to the onset of symptoms is usually one to two weeks, but can be much shorter (days), or much longer (months to years). Symptoms most often occur from May through September, because the nymphal stage of the tick is responsible for most cases.

Lyme disease is diagnosed clinically based on symptoms, objective physical findings (such as erythema migrans, facial palsy or arthritis) or a history of possible exposure to infected ticks, as well as serological blood tests. The EM rash is not always a bullseye, i.e., it can be red all the way across. When making a diagnosis of Lyme disease, health care providers should consider other diseases that may cause similar illness. Not all patients infected with Lyme disease will develop the characteristic bullseye rash and many may not recall a tick bite.

Lyme disease is classified as a zoonosis, as it is transmitted to humans from a natural reservoir among rodents by ticks that feed on both sets of hosts. Hard-bodied ticks of the genus Ixodes are the main vectors of Lyme disease. Most infections are caused by ticks in the nymphal stage, as they are very small and may feed for long periods of time undetected. Larval ticks are very rarely infected. Tick bites often go unnoticed because of the small size of the tick in its nymphal stage, as well as tick secretions that prevent the host from feeling any itch or pain from the bite. However, transmission is quite rare, with only about 1% of recognized tick bites resulting in Lyme disease; this may be because an infected tick must be attached for at least a day for transmission to occur.

Folk remedies for tick removal tend to be ineffective, offer no advantages in preventing the transfer of disease, and may increase the risks of transmission or infection. The best method is simply to pull the tick out with tweezers as close to the skin as possible, without twisting, and avoiding crushing the body of the tick or removing the head from the body. The risk of infection increases with the time the tick is attached and if a tick is attached for less than 24 hours, infection is unlikely. However, since these ticks are very small, especially in the nymph stage, prompt detection is quite difficult.

Antibiotics are the primary treatment for Lyme disease; the most appropriate antibiotic treatment depends upon the patient and the stage of the disease. According to the Infectious Diseases Society of America guidelines, the antibiotics of choice are doxycycline (in adults), amoxicillin (in children), erythromycin (for pregnant women) and ceftriaxone, with treatment lasting 10 to 28 days. Alternative choices are cefuroxime and cefotaxime. Treatment of pregnant women is similar, but doxycycline should not be used.

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