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biology

Syphilis

Syphilis is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Syphilis rather than just read about it. In short: Syphilis () is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms depend on the stage it presents: primary, secondary, latent or tertiary.

Syphilis — main illustration
Syphilis — illustration

Key takeaways

  • Syphilis belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Syphilis to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Syphilis from memory before moving on to harder problems.

Reference excerpt

Syphilis () is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms depend on the stage it presents: primary, secondary, latent or tertiary. The primary stage classically presents with a single chancre (a firm, painless, non-itchy skin ulceration usually between 1 cm and 2 cm in diameter), though there may be multiple sores. In secondary syphilis, a diffuse rash occurs, which frequently involves the palms of the hands and soles of the feet. There may also be sores in the mouth or vagina. Latent syphilis has no symptoms and can last years. In tertiary syphilis, there are gummas (soft, non-cancerous growths), neurological problems, or heart symptoms. Syphilis has been known as "the great imitator", because it may cause symptoms similar to many other diseases. Syphilis is most commonly spread through sexual activity. It may also be transmitted from mother to baby during pregnancy or at birth, resulting in congenital syphilis. Other diseases caused by Treponema bacteria include yaws (T. pallidum subspecies pertenue), pinta (T. carateum), and nonvenereal endemic syphilis (T. pallidum subspecies endemicum). These three diseases are not typically sexually transmitted. Diagnosis is usually made by using blood tests; the bacteria can also be detected using dark field microscopy. The Centers for Disease Control and Prevention (U.S.) recommends for all pregnant women to be tested. The risk of sexual transmission of syphilis can be reduced by using a latex or polyurethane condom. Syphilis can be effectively treated with antibiotics. The preferred antibiotic for most cases is benzathine benzylpenicillin injected into a muscle. In those who have a severe penicillin allergy, doxycycline or tetracycline may be used. In those with neurosyphilis, intravenous benzylpenicillin or ceftriaxone is recommended. During treatment, people may develop fever, headache, and muscle pains, known as a Jarisch–Herxheimer reaction. In 2015, about 45.4 million people had syphilis infections, of which six million were new cases. During 2015, it caused about 107,000 deaths, down from 202,000 in 1990. After decreasing dramatically with the availability of penicillin in the 1940s, rates of infection have increased since the turn of the millennium in many countries, often in combination with human immunodeficiency virus (HIV). This is believed to be partly due to unsafe drug use, increased prostitution, and decreased use of condoms.

Signs and symptoms

Syphilis can present in one of four different stages: primary, secondary, latent, and tertiary, and may also occur congenitally. There may be no symptoms. It was referred to as "the great imitator" by Sir William Osler due to its varied presentations.

Primary

Primary syphilis is typically acquired by direct sexual contact with the infectious lesions of another person. Approximately 2–6 weeks after contact (with a range of 10–90 days) a skin lesion, called a chancre, appears at the site and this contains infectious bacteria. This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders approximately 0.3–3.0 cm in size. The lesion may take on almost any form. In the classic form, it evolves from a macule to a papule and finally to an erosion or ulcer. Occasionally, multiple lesions may be present (~40%), with multiple lesions being more common when coinfected with HIV. Lesions may be painful or tender (30%), and they may occur in places other than the genitals (2–7%). The most common location in women is the cervix (44%), the penis in heterosexual men (99%), and anally and rectally in men who have sex with men (34%). Lymph node enlargement frequently (80%) occurs around the area of infection, occurring seven to 10 days after chancre formation. The lesion may persist for three to six weeks if left untreated.

Secondary

Secondary syphilis occurs approximately four to ten weeks after the primary infection. While secondary disease is known for the many different ways it can manifest, symptoms most commonly involve the skin, mucous membranes, and lymph nodes. There may be a symmetrical, reddish-pink, non-itchy rash on the trunk and extremities, including the palms and soles. The rash may become maculopapular or pustular. It may form flat, broad, whitish, wart-like lesions on mucous membranes, known as condyloma latum. All of these lesions harbor bacteria and are infectious. Other symptoms may include fever, sore throat, malaise, weight loss, hair loss, and headache. Rare manifestations include liver inflammation, kidney disease, joint inflammation, periostitis, inflammation of the optic nerve, uveitis, and interstitial keratitis. The acute symptoms usually resolve after three to six weeks; about 25% of people may present with a recurrence of secondary symptoms. Many people who present with secondary syphilis (40–85% of women, 20–65% of men) do not report previously having had the classical chancre of primary syphilis.

Latent Latent syphilis is defined as having serologic proof of infection without symptoms of disease. It develops after secondary syphilis and is divided into early latent and late latent stages. Early latent syphilis is defined by the World Health Organization as less than 2 years after original infection. Early latent syphilis is infectious as up to 25% of people can develop a recurrent secondary infection (during which bacteria are actively replicating and are infectious). Two years after the original infection the person will enter late latent syphilis and is not as infectious as in the early phase. The latent phase of syphilis can last many years after which, without treatment, approximately 15–40% of people can develop tertiary syphilis.

Tertiary

… excerpt ends here. Continue reading the full article.

Illustrations

Syphilis illustration
Syphilis: Primary syphilis on a tongue
Primary syphilis on a tongue
Syphilis: A chancre on a penis due to primary syphilis, 1978
A chancre on a penis due to primary syphilis, 1978
Syphilis: Typical presentation of secondary syphilis with a rash on the palms of the hands, 1967
Typical presentation of secondary syphilis with a rash on the palms of the hands, 1967
Syphilis: Reddish papules and nodules over much of the body due to secondary syphilis
Reddish papules and nodules over much of the body due to secondary syphilis

Worked examples

Example 1 — a first encounter with Syphilis

Start with the simplest possible case. Write down what Syphilis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Syphilis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Syphilis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Syphilis

In research
Syphilis appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Syphilis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Syphilis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacterial diseases, Bacterium-related cutaneous conditions, Infections with a predominantly sexual mode of transmission, so understanding it makes those chapters shorter.
In everyday life
Look for Syphilis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Syphilis in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Syphilis means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Syphilis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Syphilis in simple terms?

Syphilis () is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms depend on the stage it presents: primary, secondary, latent or tertiary.

Why does Syphilis matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Syphilis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Syphilis.

Tags

  • Bacterial diseases
  • Bacterium-related cutaneous conditions
  • Infections with a predominantly sexual mode of transmission
  • Infectious diseases
  • Infectious diseases with eradication efforts
  • Sexually transmitted infections
  • Spirochaetes
  • Syphilis

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