Sunday, 26 February 2012
Human Diseases: Epilepsy
Human Diseases: Epilepsy: Epilepsy (from the Ancient Greek ἐπιληψία ( epilēpsía ) — "seizure") is a common and diverse set of chronic neurological disorders charact...
Epilepsy
Epilepsy (from the Ancient Greek ἐπιληψία (epilēpsía) — "seizure") is a common and diverse set of chronic neurological disorders characterized by seizures.[1] Some definitions of epilepsy require that seizures be recurrent and unprovoked, but others require only a single seizure combined with brain alterations which increase the chance of future seizures.[4]
Epileptic seizures result from abnormal, excessive or hypersynchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy, and nearly 90% of epilepsy occurs in developing countries. Epilepsy becomes more common as people age. Onset of new cases occur most frequently in infants and the elderly. As a consequence of brain surgery, epileptic seizures may occur in recovering patients.
Epilepsy is usually controlled, but not cured, with medication. However, over 30% of people with epilepsy do not have seizure control even with the best available medications. Surgery may be considered in difficult cases. Not all epilepsy syndromes are lifelong – some forms are confined to particular stages of childhood. Epilepsy should not be understood as a single disorder, but rather as syndromic with vastly divergent symptoms, all involving episodic abnormal electrical activity in the brain and numerous seizures.
There are different causes of epilepsy that are common in certain age groups.
The proper initial response to a generalized tonic-clonic epileptic seizure is to roll the person on the side (recovery position) to prevent ingestion of fluids into the lungs, which can result in choking and death. Should the person regurgitate, this should be allowed to drip out the side of the person's mouth. The person should be prevented from self-injury by moving them away from sharp edges, and placing something soft beneath the head. If a seizure lasts longer than 5 minutes, or if more than one seizure occurs without regaining consciousness emergency medical services should be contacted.
Availability - Currently there are 20 medications approved by the Food and Drug Administration for the use of treatment of epileptic seizures in the US: carbamazepine (common US brand name Tegretol), clorazepate (Tranxene), clonazepam (Klonopin), ethosuximide (Zarontin), felbamate (Felbatol), fosphenytoin (Cerebyx), gabapentin (Neurontin), lacosamide (Vimpat), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), phenobarbital (Luminal), phenytoin (Dilantin), pregabalin (Lyrica), primidone (Mysoline), tiagabine (Gabitril), topiramate (Topamax), valproate semisodium (Depakote), valproic acid (Depakene), and zonisamide (Zonegran). Most of these appeared after 1990.
Medications commonly available outside the US but still labelled as "investigational" within the US are clobazam (Frisium) and vigabatrin (Sabril). Medications currently under clinical trial under the supervision of the FDA include retigabine, brivaracetam, and seletracetam.
Other drugs are commonly used to abort an active seizure or interrupt a seizure flurry; these include diazepam (Valium, Diastat) and lorazepam (Ativan). Drugs used only in the treatment of refractory status epilepticus include paraldehyde (Paral), midazolam (Versed), and pentobarbital (Nembutal).
Some anticonvulsant medications do not have primary FDA-approved uses in epilepsy but are used in limited trials, remain in rare use in difficult cases, have limited "grandfather" status, are bound to particular severe epilepsies, or are under current investigation. These include acetazolamide (Diamox), progesterone, adrenocorticotropic hormone (ACTH, Acthar), various corticotropic steroid hormones (prednisone), or bromide.
Effectiveness - The definition of "effective" varies. FDA approval usually requires that 50% of the patient treatment group had at least a 50% improvement in the rate of epileptic seizures. About 20% of patients with epilepsy continue to have breakthrough epileptic seizures despite best anticonvulsant treatment
Safety and Side Effects - 88% of patients with epilepsy, in a European survey, reported at least one anticonvulsant related side-effect. Most side effects are mild and "dose-related" and can often be avoided or minimized by the use of the smallest effective amount. Some examples include mood changes, sleepiness, or unsteadiness in gait. Some anticonvulsant medications have "idiosyncratic" side effects that can not be predicted by dose. Some examples include drug rashes, liver toxicity (hepatitis), or aplastic anemia. Safety includes the consideration of teratogenicity (the effects of medications on fetal development) when women with epilepsy become pregnant.
Principles of Anticonvulsant Use and Management - The goal for individual patients is no seizures and minimal side-effects, and the job of the physician is to aid the patient to find the best balance between the two during the prescribing of anticonvulsants. Most patients can achieve this balance best with monotherapy, the use of a single anticonvulsant medication. Some patients, however, require polypharmacy, the use of two or more anticonvulsants.
Serum levels of AEDs can be checked to determine medication compliance, to assess the effects of new drug-drug interactions upon previous stable medication levels, or to help establish if particular symptoms such as instability or sleepiness can be considered a drug side effect or are due to different causes. Children or impaired adults who may not be able to communicate side-effects may benefit from routine screening of drug levels. Beyond baseline screening, however, trials of recurrent, routine blood or urine monitoring show no proven benefits and may lead to unnecessary medication adjustments in most older children and adults using routine anticonvulsants.
If a person's epilepsy cannot be brought under control after adequate trials of two or three (experts vary here) different drugs, that person's epilepsy is generally said to be medically refractory. A study of patients with previously untreated epilepsy demonstrated that 47% achieved control of seizures with the use of their first single drug. 14% became seizure free during treatment with a second or third drug. An additional 3% became seizure-free with the use of two drugs simultaneously. Other treatments, in addition to or instead of, anticonvulsant medications may be considered by those people with continuing seizures.
The evaluation for epilepsy surgery is designed to locate the "epileptic focus" (the location of the epileptic abnormality) and to determine if resective surgery will affect normal brain function. Physicians will also confirm the diagnosis of epilepsy to make sure that spells arise from epilepsy (as opposed to non-epileptic seizures). The evaluation typically includes neurological examination, routine EEG, Long-term video-EEG monitoring, neuropsychological evaluation, and neuroimaging such as MRI, Single photon emission computed tomography (SPECT), positron emission tomography (PET). Some epilepsy centers use intracarotid sodium amobarbital test (Wada test), functional MRI or Magnetoencephalography (MEG) as supplementary tests.
Certain lesions require Long-term video-EEG monitoring with the use of intracranial electrodes if noninvasive testing was inadequate to identify the epileptic focus or distinguish the surgical target from normal brain tissue and function. Brain mapping by the technique of cortical electrical stimulation or Electrocorticography are other procedures used in the process of invasive testing in some patients.
The most common surgeries are the resection of lesions like tumors or arteriovenous malformations, which, in the process of treating the underlying lesion, often result in control of epileptic seizures caused by these lesions.
Other lesions are more subtle and feature epilepsy as the main or sole symptom. The most common form of intractable epilepsy in these disorders in adults is temporal lobe epilepsy with hippocampal sclerosis, and the most common type of epilepsy surgery is the anterior temporal lobectomy, or the removal of the front portion of the temporal lobe including the amygdala and hippocampus. Some neurosurgeons recommend selective amygdalahippocampectomy because of possible benefits in postoperative memory or language function. Surgery for temporal lobe epilepsy is effective, durable, and results in decreased health care costs. Despite the efficacy of epilepsy surgery, some patients decide not to undergo surgery owing to fear or the uncertainty of having a brain operation.
Palliative surgery for epilepsy is intended to reduce the frequency or severity of seizures. Examples are callosotomy or commissurotomy to prevent seizures from generalizing (spreading to involve the entire brain), which results in a loss of consciousness. This procedure can therefore prevent injury due to the person falling to the ground after losing consciousness. It is performed only when the seizures cannot be controlled by other means. Multiple subpial transection can also be used to decrease the spread of seizures across the cortex especially when the epileptic focus is located near important functional areas of the cortex. Resective surgery can be considered palliative if it is undertaken with the expectation that it will reduce but not eliminate seizures.
Hemispherectomy involves removal or a functional disconnection of most or all of one half of the cerebrum. It is reserved for people suffering from the most catastrophic epilepsies, such as those due to Rasmussen syndrome. If the surgery is performed on very young patients (2–5 years old), the remaining hemisphere may acquire some rudimentary motor control of the ipsilateral body; in older patients, paralysis results on the side of the body opposite to the part of the brain that was removed. Because of these and other side-effects, it is usually reserved for patients having exhausted other treatment options.
While far from a cure, operant-based biofeedback based on conditioning of EEG waves has some experimental support (see Professional practice of behavior analysis). Overall, the support is based on a handful of studies reviewed by Barry Sterman. These studies report a 30% reduction in weekly seizures.
Electrical stimulation methods of anticonvulsant treatment are both currently approved for treatment and investigational uses. A currently approved device is vagus nerve stimulation (VNS). Investigational devices include the responsive neurostimulation system (RNS) and deep brain stimulation (DBS).
Avoidance therapy consists of minimizing or eliminating triggers in patients whose seizures are particularly susceptible to seizure precipitants (see above). For example, sunglasses that counter exposure to particular light wavelengths can improve seizure control in certain photosensitive epilepsies.
Canine warning system is where a seizure response dog, a form of service dog, is trained to summon help or ensure personal safety when a seizure occurs. These are not suitable for everybody, and not all dogs can be so trained. Rarely, a dog may develop the ability to sense a seizure before it occurs. Development of electronic forms of seizure detection systems are currently under investigation.
Seizure prediction-based devices using long-term EEG recordings is presently being evaluated as a new way to stop epileptic seizures before they appear clinically.
Alternative or complementary medicine, including acupuncture, psychological interventions, vitamins and yoga, was evaluated in a number of systematic reviews by the Cochrane Collaboration into treatments for epilepsy, and found there is no reliable evidence to support the use of these as treatments for epilepsy. Exercise or other physical activity have also been proposed as efficacious strategies for preventing or treating epilepsy.
Epileptic seizures result from abnormal, excessive or hypersynchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy, and nearly 90% of epilepsy occurs in developing countries. Epilepsy becomes more common as people age. Onset of new cases occur most frequently in infants and the elderly. As a consequence of brain surgery, epileptic seizures may occur in recovering patients.
Epilepsy is usually controlled, but not cured, with medication. However, over 30% of people with epilepsy do not have seizure control even with the best available medications. Surgery may be considered in difficult cases. Not all epilepsy syndromes are lifelong – some forms are confined to particular stages of childhood. Epilepsy should not be understood as a single disorder, but rather as syndromic with vastly divergent symptoms, all involving episodic abnormal electrical activity in the brain and numerous seizures.
Signs and symptoms
Epilepsy is characterized by a long term risk of recurrent seizures. These seizures may present in a number of different ways.Causes
The diagnosis of epilepsy usually requires that the seizures occur spontaneously. Nevertheless, certain epilepsy syndromes require particular precipitants or triggers for seizures to occur. These are termed reflex epilepsy. For example, patients with primary reading epilepsy have seizures triggered by reading. Photosensitive epilepsy can be limited to seizures triggered by flashing lights. Other precipitants can trigger an epileptic seizure in patients who otherwise would be susceptible to spontaneous seizures. For example, children with childhood absence epilepsy may be susceptible to hyperventilation. In fact, flashing lights and hyperventilation are activating procedures used in clinical EEG to help trigger seizures to aid diagnosis. Finally, other precipitants can facilitate, rather than obligately trigger, seizures in susceptible individuals. Emotional stress, sleep deprivation, sleep itself, heat stress, alcohol and febrile illness are examples of precipitants cited by patients with epilepsy. Notably, the influence of various precipitants varies with the epilepsy syndrome. Likewise, the menstrual cycle in women with epilepsy can influence patterns of seizure recurrence. Catamenial epilepsy is the term denoting seizures linked to the menstrual cycle.There are different causes of epilepsy that are common in certain age groups.
- During the neonatal period and early infancy the most common causes include hypoxic-ischemic encephalopathy, CNS infections, trauma, congenital CNS abnormalities, and metabolic disorders.
- During late infancy and early childhood, febrile seizures are fairly common. These may be caused by many different things, some thought to be things such as CNS infections and trauma.
- During childhood, well-defined epilepsy syndromes are generally seen.
- During adolescence and adulthood, the causes are more likely to be secondary to any CNS lesion. Further, idiopathic epilepsy is less common. Other causes associated with these age groups are stress, trauma, CNS infections, brain tumors, illicit drug use and alcohol withdrawal.
- In older adults, cerebrovascular disease is a very common cause. Other causes are CNS tumors, head trauma, and other degenerative diseases that are common in the older age group, such as dementia
Management
Epilepsy is usually treated with medication prescribed by a physician; primary caregivers, neurologists, and neurosurgeons all frequently care for people with epilepsy. However, it has been stressed that accurate differentiation between generalized and partial seizures is especially important in determining the appropriate treatment. In some cases the implantation of a stimulator of the vagus nerve, or a special diet can be helpful. Neurosurgical operations for epilepsy can be palliative, reducing the frequency or severity of seizures; or, in some patients, an operation can be curative.The proper initial response to a generalized tonic-clonic epileptic seizure is to roll the person on the side (recovery position) to prevent ingestion of fluids into the lungs, which can result in choking and death. Should the person regurgitate, this should be allowed to drip out the side of the person's mouth. The person should be prevented from self-injury by moving them away from sharp edges, and placing something soft beneath the head. If a seizure lasts longer than 5 minutes, or if more than one seizure occurs without regaining consciousness emergency medical services should be contacted.
Medications
Main article: Anticonvulsant
The mainstay of treatment of epilepsy is anticonvulsant medications.
Often, anticonvulsant medication treatment will be lifelong and can have
major effects on quality of life. The choice among anticonvulsants and
their effectiveness differs by epilepsy syndrome. Mechanisms,
effectiveness for particular epilepsy syndromes, and side-effects differ
among the individual anticonvulsant medications. Some general findings
about the use of anticonvulsants are outlined below.Availability - Currently there are 20 medications approved by the Food and Drug Administration for the use of treatment of epileptic seizures in the US: carbamazepine (common US brand name Tegretol), clorazepate (Tranxene), clonazepam (Klonopin), ethosuximide (Zarontin), felbamate (Felbatol), fosphenytoin (Cerebyx), gabapentin (Neurontin), lacosamide (Vimpat), lamotrigine (Lamictal), levetiracetam (Keppra), oxcarbazepine (Trileptal), phenobarbital (Luminal), phenytoin (Dilantin), pregabalin (Lyrica), primidone (Mysoline), tiagabine (Gabitril), topiramate (Topamax), valproate semisodium (Depakote), valproic acid (Depakene), and zonisamide (Zonegran). Most of these appeared after 1990.
Medications commonly available outside the US but still labelled as "investigational" within the US are clobazam (Frisium) and vigabatrin (Sabril). Medications currently under clinical trial under the supervision of the FDA include retigabine, brivaracetam, and seletracetam.
Other drugs are commonly used to abort an active seizure or interrupt a seizure flurry; these include diazepam (Valium, Diastat) and lorazepam (Ativan). Drugs used only in the treatment of refractory status epilepticus include paraldehyde (Paral), midazolam (Versed), and pentobarbital (Nembutal).
Some anticonvulsant medications do not have primary FDA-approved uses in epilepsy but are used in limited trials, remain in rare use in difficult cases, have limited "grandfather" status, are bound to particular severe epilepsies, or are under current investigation. These include acetazolamide (Diamox), progesterone, adrenocorticotropic hormone (ACTH, Acthar), various corticotropic steroid hormones (prednisone), or bromide.
Effectiveness - The definition of "effective" varies. FDA approval usually requires that 50% of the patient treatment group had at least a 50% improvement in the rate of epileptic seizures. About 20% of patients with epilepsy continue to have breakthrough epileptic seizures despite best anticonvulsant treatment
Safety and Side Effects - 88% of patients with epilepsy, in a European survey, reported at least one anticonvulsant related side-effect. Most side effects are mild and "dose-related" and can often be avoided or minimized by the use of the smallest effective amount. Some examples include mood changes, sleepiness, or unsteadiness in gait. Some anticonvulsant medications have "idiosyncratic" side effects that can not be predicted by dose. Some examples include drug rashes, liver toxicity (hepatitis), or aplastic anemia. Safety includes the consideration of teratogenicity (the effects of medications on fetal development) when women with epilepsy become pregnant.
Principles of Anticonvulsant Use and Management - The goal for individual patients is no seizures and minimal side-effects, and the job of the physician is to aid the patient to find the best balance between the two during the prescribing of anticonvulsants. Most patients can achieve this balance best with monotherapy, the use of a single anticonvulsant medication. Some patients, however, require polypharmacy, the use of two or more anticonvulsants.
Serum levels of AEDs can be checked to determine medication compliance, to assess the effects of new drug-drug interactions upon previous stable medication levels, or to help establish if particular symptoms such as instability or sleepiness can be considered a drug side effect or are due to different causes. Children or impaired adults who may not be able to communicate side-effects may benefit from routine screening of drug levels. Beyond baseline screening, however, trials of recurrent, routine blood or urine monitoring show no proven benefits and may lead to unnecessary medication adjustments in most older children and adults using routine anticonvulsants.
If a person's epilepsy cannot be brought under control after adequate trials of two or three (experts vary here) different drugs, that person's epilepsy is generally said to be medically refractory. A study of patients with previously untreated epilepsy demonstrated that 47% achieved control of seizures with the use of their first single drug. 14% became seizure free during treatment with a second or third drug. An additional 3% became seizure-free with the use of two drugs simultaneously. Other treatments, in addition to or instead of, anticonvulsant medications may be considered by those people with continuing seizures.
Surgery
Epilepsy surgery is an option for people with focal seizures that remain resistant to treatment. The goal for these procedures is total control of epileptic seizures, although anticonvulsant medications may still be required.The evaluation for epilepsy surgery is designed to locate the "epileptic focus" (the location of the epileptic abnormality) and to determine if resective surgery will affect normal brain function. Physicians will also confirm the diagnosis of epilepsy to make sure that spells arise from epilepsy (as opposed to non-epileptic seizures). The evaluation typically includes neurological examination, routine EEG, Long-term video-EEG monitoring, neuropsychological evaluation, and neuroimaging such as MRI, Single photon emission computed tomography (SPECT), positron emission tomography (PET). Some epilepsy centers use intracarotid sodium amobarbital test (Wada test), functional MRI or Magnetoencephalography (MEG) as supplementary tests.
Certain lesions require Long-term video-EEG monitoring with the use of intracranial electrodes if noninvasive testing was inadequate to identify the epileptic focus or distinguish the surgical target from normal brain tissue and function. Brain mapping by the technique of cortical electrical stimulation or Electrocorticography are other procedures used in the process of invasive testing in some patients.
The most common surgeries are the resection of lesions like tumors or arteriovenous malformations, which, in the process of treating the underlying lesion, often result in control of epileptic seizures caused by these lesions.
Other lesions are more subtle and feature epilepsy as the main or sole symptom. The most common form of intractable epilepsy in these disorders in adults is temporal lobe epilepsy with hippocampal sclerosis, and the most common type of epilepsy surgery is the anterior temporal lobectomy, or the removal of the front portion of the temporal lobe including the amygdala and hippocampus. Some neurosurgeons recommend selective amygdalahippocampectomy because of possible benefits in postoperative memory or language function. Surgery for temporal lobe epilepsy is effective, durable, and results in decreased health care costs. Despite the efficacy of epilepsy surgery, some patients decide not to undergo surgery owing to fear or the uncertainty of having a brain operation.
Palliative surgery for epilepsy is intended to reduce the frequency or severity of seizures. Examples are callosotomy or commissurotomy to prevent seizures from generalizing (spreading to involve the entire brain), which results in a loss of consciousness. This procedure can therefore prevent injury due to the person falling to the ground after losing consciousness. It is performed only when the seizures cannot be controlled by other means. Multiple subpial transection can also be used to decrease the spread of seizures across the cortex especially when the epileptic focus is located near important functional areas of the cortex. Resective surgery can be considered palliative if it is undertaken with the expectation that it will reduce but not eliminate seizures.
Hemispherectomy involves removal or a functional disconnection of most or all of one half of the cerebrum. It is reserved for people suffering from the most catastrophic epilepsies, such as those due to Rasmussen syndrome. If the surgery is performed on very young patients (2–5 years old), the remaining hemisphere may acquire some rudimentary motor control of the ipsilateral body; in older patients, paralysis results on the side of the body opposite to the part of the brain that was removed. Because of these and other side-effects, it is usually reserved for patients having exhausted other treatment options.
Other
A ketogenic diet (high-fat, low-carbohydrate) was first tested in the 1920s, but became less used with the advent of effective anticonvulsants. In the 1990s specialized diets again gained traction within the medical community. The mechanism of action is unknown. It is used mainly in the treatment of children with severe, medically intractable epilepsies, and the New York Times reported that use is supported by peer-reviewed research that found that the diet reduced seizures among drug-resistant epileptics by >50% in 38% of patients and by >90% in 7% of patients.While far from a cure, operant-based biofeedback based on conditioning of EEG waves has some experimental support (see Professional practice of behavior analysis). Overall, the support is based on a handful of studies reviewed by Barry Sterman. These studies report a 30% reduction in weekly seizures.
Electrical stimulation methods of anticonvulsant treatment are both currently approved for treatment and investigational uses. A currently approved device is vagus nerve stimulation (VNS). Investigational devices include the responsive neurostimulation system (RNS) and deep brain stimulation (DBS).
- Vagus nerve stimulation (US manufacturer Cyberonics) consists of a computerized electrical device similar in size, shape and implant location to a heart pacemaker that connects to the vagus nerve in the neck. The device stimulates the vagus nerve at preset intervals and intensities of current. Efficacy has been tested in patients with localization-related epilepsies, demonstrating 50% of patients experience a 50% improvement in seizure rate. Case series have demonstrated similar efficacies in certain generalized epilepsies, such as Lennox-Gastaut syndrome. Although success rates are not usually equal to that of epilepsy surgery, it is a reasonable alternative when the patient is reluctant to proceed with any required invasive monitoring, when appropriate presurgical evaluation fails to uncover the location of epileptic foci, or when there are multiple epileptic foci.
- Responsive neurostimulator system (US manufacturer Neuropace) consists of a computerized electrical device implanted in the skull, with electrodes implanted in presumed epileptic foci within the brain. The brain electrodes send EEG signals to the device, which contains seizure-detection software. When certain EEG seizure criteria are met, the device delivers a small electrical charge to other electrodes near the epileptic focus, which disrupt the seizure. The efficacy of the RNS is under current investigation with the goal of FDA approval.
- Deep brain stimulation (US manufacturer Medtronic) consists of a computerized electrical device implanted in the chest in a manner similar to the VNS, but electrical stimulation is delivered to deep brain structures through depth electrodes implanted through the skull. In epilepsy, the electrode target is the anterior nucleus of the thalamus. The efficacy of the DBS in localization-related epilepsies is currently under investigation.
Avoidance therapy consists of minimizing or eliminating triggers in patients whose seizures are particularly susceptible to seizure precipitants (see above). For example, sunglasses that counter exposure to particular light wavelengths can improve seizure control in certain photosensitive epilepsies.
Canine warning system is where a seizure response dog, a form of service dog, is trained to summon help or ensure personal safety when a seizure occurs. These are not suitable for everybody, and not all dogs can be so trained. Rarely, a dog may develop the ability to sense a seizure before it occurs. Development of electronic forms of seizure detection systems are currently under investigation.
Seizure prediction-based devices using long-term EEG recordings is presently being evaluated as a new way to stop epileptic seizures before they appear clinically.
Alternative or complementary medicine, including acupuncture, psychological interventions, vitamins and yoga, was evaluated in a number of systematic reviews by the Cochrane Collaboration into treatments for epilepsy, and found there is no reliable evidence to support the use of these as treatments for epilepsy. Exercise or other physical activity have also been proposed as efficacious strategies for preventing or treating epilepsy.
Wednesday, 15 February 2012
Human Diseases: Sexually transmitted disease
Human Diseases: Sexually transmitted disease: Sexually transmitted infections ( STI ), also previously referred to as sexually transmitted diseases ( STD ) or venereal diseases ( VD ...
Sexually transmitted disease
Sexually transmitted infections (STI), also previously referred to as sexually transmitted diseases (STD) or venereal diseases (VD), are illnesses that has a significant probability of transmission between humans by means of human sexual behavior, including vaginal intercourse, oral sex, and anal sex. While in the past, these illnesses have mostly been referred to as STDs or VD, in recent years the term sexually transmitted infections (STIs) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without having a disease. Some STIs can also be transmitted via the use of IV drug needles after its use by an infected person, as well as through childbirth or breastfeeding. Sexually transmitted infections have been well known for hundreds of years
Sexually transmitted infection is a broader term than sexually transmitted disease.[1] An infection is a colonization by a parasitic species, which may not cause any adverse effects. In a disease the infection leads to impaired or abnormal function. In either case the condition may not exhibit signs or symptoms. Increased understanding of infections like HPV, which infects most sexually active individuals but cause disease in only a few has led to increased use of the term STI. Public health officials originally introduced the term sexually transmitted infection, which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former.[citation needed]
STD may refer only to infections that are causing diseases, or it may be used more loosely as a synonym for STI. Because most of the time people do not know that they are infected with an STD until they are tested or start showing symptoms of disease, most people use the term STD, even though the term STI is also appropriate in many cases.
Moreover, the term sexually transmissible disease is sometimes used since it is less restrictive in consideration of other factors or means of transmission. For instance, meningitis is transmissible by means of sexual contact but is not labeled as an STI because sexual contact is not the primary vector for the pathogens that cause meningitis. This discrepancy is addressed by the probability of infection by means other than sexual contact. In general, an STI is an infection that has a negligible probability of transmission by means other than sexual contact, but has a realistic means of transmission by sexual contact (more sophisticated means—blood transfusion, sharing of hypodermic needles—are not taken into account). Thus, one may presume that, if a person is infected with an STI, e.g., chlamydia, gonorrhea, genital herpes, it was transmitted to him/her by means of sexual contact.
The diseases on this list are most commonly transmitted solely by sexual activity. Many infectious diseases, including the common cold, influenza, pneumonia, and most others that are transmitted person-to-person can also be transmitted during sexual contact, if one person is infected, due to the close contact involved. However, even though these diseases may be transmitted during sex, they are not considered STDs.
Micrograph showing the viral cytopathic effect of herpes (ground glass nuclear inclusions, multi-nucleation). Pap test. Pap stain.
The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. Not all sexual activities involve contact: cybersex, phonesex or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk. Although a condom is effective in limiting exposure, some disease transmission may occur even with a condom.[16]
Ideally, both partners should get tested for STIs before initiating sexual contact, or before resuming contact if a partner engaged in contact with someone else. Many infections are not detectable immediately after exposure, so enough time must be allowed between possible exposures and testing for the tests to be accurate. Certain STIs, particularly certain persistent viruses like HPV, may be impossible to detect with current medical procedures.
Many diseases that establish permanent infections can so occupy the immune system that other diseases become more easily transmitted. The innate immune system led by defensins against HIV can prevent transmission of HIV when viral counts are very low, but if busy with other viruses or overwhelmed, HIV can establish itself. Certain viral STI's also greatly increase the risk of death for HIV infected patients.
Classification
Until the 1990s, STDs were commonly known as venereal diseases: Veneris is the Latin genitive form of the name Venus, the Roman goddess of love. Social disease was another euphemism.Sexually transmitted infection is a broader term than sexually transmitted disease.[1] An infection is a colonization by a parasitic species, which may not cause any adverse effects. In a disease the infection leads to impaired or abnormal function. In either case the condition may not exhibit signs or symptoms. Increased understanding of infections like HPV, which infects most sexually active individuals but cause disease in only a few has led to increased use of the term STI. Public health officials originally introduced the term sexually transmitted infection, which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former.[citation needed]
STD may refer only to infections that are causing diseases, or it may be used more loosely as a synonym for STI. Because most of the time people do not know that they are infected with an STD until they are tested or start showing symptoms of disease, most people use the term STD, even though the term STI is also appropriate in many cases.
Moreover, the term sexually transmissible disease is sometimes used since it is less restrictive in consideration of other factors or means of transmission. For instance, meningitis is transmissible by means of sexual contact but is not labeled as an STI because sexual contact is not the primary vector for the pathogens that cause meningitis. This discrepancy is addressed by the probability of infection by means other than sexual contact. In general, an STI is an infection that has a negligible probability of transmission by means other than sexual contact, but has a realistic means of transmission by sexual contact (more sophisticated means—blood transfusion, sharing of hypodermic needles—are not taken into account). Thus, one may presume that, if a person is infected with an STI, e.g., chlamydia, gonorrhea, genital herpes, it was transmitted to him/her by means of sexual contact.
The diseases on this list are most commonly transmitted solely by sexual activity. Many infectious diseases, including the common cold, influenza, pneumonia, and most others that are transmitted person-to-person can also be transmitted during sexual contact, if one person is infected, due to the close contact involved. However, even though these diseases may be transmitted during sex, they are not considered STDs.
Cause
Bacterial
- Chancroid (Haemophilus ducreyi)
- Chlamydia (Chlamydia trachomatis)
- Granuloma inguinale or (Klebsiella granulomatis)
- Gonorrhea (Neisseria gonorrhoeae)
- Syphilis (Treponema pallidum)
Fungal
- Candidiasis (yeast infection)
Viral
- Viral hepatitis (Hepatitis B virus)—saliva, venereal fluids.
(Note: Hepatitis A and Hepatitis E are transmitted via the fecal-oral route; Hepatitis C is rarely sexually transmittable,[2] and the route of transmission of Hepatitis D (only if infected with B) is uncertain, but may include sexual transmission.[3][4][5]) - Herpes simplex (Herpes simplex virus 1, 2) skin and mucosal, transmissible with or without visible blisters
- HIV (Human Immunodeficiency Virus)—venereal fluids, semen, breast milk, blood
- HPV (Human Papillomavirus)—skin and mucosal contact. 'High risk' types of HPV cause almost all cervical cancers, as well as some anal, penile, and vulvar cancer. Some other types of HPV cause genital warts.
- Molluscum contagiosum (molluscum contagiosum virus MCV)—close contact
Parasites
- Crab louse, colloquially known as "crabs" or "pubic lice" (Pthirus pubis)
- Scabies (Sarcoptes scabiei)
Protozoal
Prevention
Main article: Safe sex
Prevention is key in addressing incurable STIs, such as HIV & herpes. Sexual health clinics fight to promote the use of condoms and provide outreach for at-risk communities.The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. Not all sexual activities involve contact: cybersex, phonesex or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk. Although a condom is effective in limiting exposure, some disease transmission may occur even with a condom.[16]
Ideally, both partners should get tested for STIs before initiating sexual contact, or before resuming contact if a partner engaged in contact with someone else. Many infections are not detectable immediately after exposure, so enough time must be allowed between possible exposures and testing for the tests to be accurate. Certain STIs, particularly certain persistent viruses like HPV, may be impossible to detect with current medical procedures.
Many diseases that establish permanent infections can so occupy the immune system that other diseases become more easily transmitted. The innate immune system led by defensins against HIV can prevent transmission of HIV when viral counts are very low, but if busy with other viruses or overwhelmed, HIV can establish itself. Certain viral STI's also greatly increase the risk of death for HIV infected patients.
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