HEPATITIS B VIRUS - detection from blood

HEPATITIS B VIRUS (HBV)

OVERVIEW

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease; it is caused by the hepatitis B virus (HBV). 

For many people, hepatitis B is a short-term illness. For others, it can become a long-term, chronic infection (lasting >6 months) that can lead to serious, even life-threatening health issues. This is because chronic HBV infection increases the risk of developing conditions that permanently scar the liver: liver failure, cancer or cirrhosis. These complications cause high morbidity and mortality. Hence, hepatitis B is a major global health problem. 

    Most adults with hepatitis B recover fully, even if their signs and symptoms are severe. Infants and children are more likely to develop a chronic, long-lasting HBV infection. Risk for chronic infection is therefore related to age at infection: about 90% of infants with hepatitis B go on to develop chronic infection, whereas only 2%-6% of people who get hepatitis B as adults become chronically infected. The best way to prevent hepatitis B is to get vaccinated. Vaccines can prevent hepatitis B. If you're infected, taking certain  precautions can help prevent spreading the virus to others. 

SYMPTOMS

Signs and symptoms of HBV range from mild to severe. They usually appear at 1-4 months after infection, but they can also appear as early as 2 weeks post-infection. Most people do not experience any symptoms when newly infected; especially young children may not have any symptoms. However, some people have acute illness with symptoms that last several weeks.

HBV signs and symptoms may include: 

- abdominal pain

- dark urine 

- fever

- joint pain

- loss of appetite

- nausea and vomiting 

- weakness and (extreme) fatigue

- yellowing of the skin and of the whites of the eyes (jaundice) 

TRANSMISSION

In highly endemic areas, hepatitis B is most commonly spread from mother to child at birth (perinatal transmission) or through horizontal transmission (exposure to infected blood), especially from an infected child to an uninfected child during the first 5 years of life. The development of chronic infection is common in infants from their mothers and before the age of 5 years old.   

Hepatitis B is also spread by needlestick injury, tattooing, piercing and exposure to infected blood and body fluids, such as saliva and menstrual, vaginal and seminal fluids. Transmission of the virus may also occur through the reuse of contaminated needles and syringes or sharp objects either in health care settings, in the community or among people who inject drugs. Sexual transmission is more prevalent in unvaccinated people with multiple sexual partners. 

The hepatitis B virus can survive outside the body for at least 7 days. During this time, the virus can still cause infection if it enters the body of a person who is not protected by the vaccine. The incubation period of the hepatitis B virus ranges from 30 to 180 days. The virus may be detected within 30 to 60 days after infection and can persist and develop into chronic hepatitis B, especially when transmitted in infancy or childhood.

DIAGNOSIS

It is not possible on clinical grounds to differentiate hepatitis B from hepatitis caused by other viral agents, hence laboratory confirmation of the diagnosis is essential. Several blood tests are available to diagnose and monitor people with hepatitis B. They can be used to distinguish acute and chronic infections. WHO recommends that all blood donations be tested for hepatitis B to ensure blood safety and to avoid accidental transmission.  

As of 2019, only around 10.5% of all people estimated to be living with hepatitis B were aware of their infection, while around 22% of the people diagnosed were on treatment. In settings with high hepatitis B surface antigen seroprevalence in the general population (defined as ≥2% or ≥5% HBsAg seroprevalence), WHO recommends that all adults have access to and be offered HBsAg testing with linkage to prevention, care and treatment services as needed.

Newly diagnosed with hepatitis B: Nearly 1 in 3 people worldwide will be infected with the HBV in their lifetime. If one knows having been exposed to hepatitis B, the doctor should be contacted immediately. A preventive treatment may reduce the risk of infection if receiving the treatment within 24h of exposure to the virus.

First steps

1. Understand our diagnosis. Do you have an acute or a chronic infection? When someone is first infected with HBV, it is considered an acute infection. Most healthy adults are able to get rid of the virus on their own when acutely infected. If testing remains positive after 6 months, it is considered a chronic infection. Knowing whether hepatitis B is acute or chronic helps determining the next steps.

2. Prevent the Spread to Others. Hepatitis B can be transmitted to others through blood and bodily fluids, but there are safe and effective vaccines that can protect from hepatitis B. Patients should also be aware of how to avoid passing the infection to family, household members and sexual partners. 

3. Find a Physician. If chronic hepatitis B have been diagnosed, it is important to find a doctor with expertise in treating liver disease. 

4. Educate Yourself. It is important that patients get the facts about hepatitis B, including what it is, who gets it, and possible symptoms, starting with "What is Hepatitis B". 

Hepatitis B virus - diagnosing options and their acronyms:

- serological markers associated with hepatitis B virus infection:

          - AgHBs - HBV infection; hepatitis B virus antigens detectable from incubation until 3-4 months after infection;

     - AgHBe - along with HBV DNA, these hepatitis B virus antigens appear in serum immediately after the usual antigens (AgHBs); these particular antigen are indicators of active virus replication;

         - anti-HBc antibodies - undefined persistence; anti-HBc IgM are serum detectable a bit before the clinical debut, along with transaminases rise; indicators of acute phase;

       - anti-HBe antibodies - self-limiting infections;

        - anti-HBs antibodies - 4-6 months after infection; on curing; virus replication stop markers;

- HBV DNA copy-number = most sensible marker of active HBV replication. 

CAUSES

HBV infection is caused by the hepatitis B virus (HBV), which is passed from person to person through body fluids. Common ways that HBV can spread are: 

- Close contact: the virus can pass from the infected person to the uninfected one through blood, saliva, semen or vaginal secretions. This contamination can happen through sexual contact, sharing needles, syringes or other drug-injection equipment; from mother to baby at birth. 

- Sharing of needles. HBV easily spreads through needles and syringes contaminated with infected blood.

- Accidental needle sticks. HBV is a concern for health care workers and anyone else who comes in contact with human blood. 

- Mother to child. Pregnant women infected with HBV can pass the virus to their babies during childbirth. However, the newborn can be vaccinated to avoid getting infected in almost all cases. It is good to get tested for HBV if pregnant or if getting ready to become pregnant.  

ACUTE VS CHRONIC HBV

HBV infection: short-lived (acute) or long lasting (chronic). 

- Acute hepatitis B infection lasts <6 months. The immune system likely can clear acute hepatitis B from the body and one can completely recover within a few months. Most people who get hepatitis B as adults have an acute infection, but it can lead to chronic infection. 

- Chronic hepatitis B infection lasts ≥6 months. It lingers because the immune system can't fight off the infection. Chronic hepatitis B infection may last a lifetime, possibly leading to serious illnesses such as cirrhosis and liver cancer. 

The younger the age of getting HBV (particularly newborns or <5 years old children), the higher the risk of the infection becoming chronic. Chronic infection may go undetected for decades until a person becomes seriously ill from liver disease. 

COMPLICATIONS

Having a chronic HBV infection can lead to serious complications, such as: 

- Scarring of the liver (cirrhosis). The inflammation associated with an HBV infection can lead to extensive liver scarring (cirrhosis), which may impair the liver's ability to function.

- Liver cancer. People with chronic HBV infection have an increased risk of liver cancer. 

- Liver failure. Acute liver failure is a condition in which the vital functions of the liver shut down. When that occurs, a liver transplant is necessary to sustain life.

- Other conditions. People with chronic HBV may develop kidney disease or inflammation of blood vessels. 

HBV-HIV Coinfection

Some of the people living with HBV infection are also infected with HIV. Conversely, the global prevalence of HBV infection in HIV-infected individuals is around 7.4%. 

Since 2015, WHO has recommended HBV treatment for everyone diagnosed with HIV infection, regardless of the stage of disease. Tenofovir, which is included in the treatment combinations recommended as first-line therapy for HIV infection, is also active against HBV. 

TREATMENT

For acute hepatitis B, care is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids lost from vomiting and diarrhea. 

Chronic hepatitis B can be treated with oral antiviral medication. Treatment can slow the progression of cirrhosis, reduce incidence of liver cancer and improve long term survival.

WHO recommends the use of oral treatments (tenofovir or entecavir) as the most potent drugs to suppress hepatitis B virus. Most people who start hepatitis B treatment must continue it for life. 

In low-income settings, most people with liver cancer die within months of diagnosis. In high-income countries, patient present to hospital earlier in the course of the disease, and have access to surgery and chemotherapy which can prolong life for several months to a few years. Liver transplantation is sometimes used in people with cirrhosis or liver cancer in high-income countries, with varying success.  

PREVENTION

Hepatitis B can be prevented by vaccines that are safe, available and effective. The available vaccines offer 98-100% protection against hepatitis B. Preventing hepatitis B infection averts the development of complications including chronic disease and liver cancer. The HBV vaccine is typically given as 3 or 4 injections over 6 months and is recommended for:

- newborns

- children and adolescents not vaccinated at birth

- people who live with someone who has hepatitis B

- health care workers, emergency workers and other people who come into contact with blood

- anyone who has a sexually transmitted infection, including HIV

- men who have sex with men

- people who have multiple sexual partners

- sexual partners of someone who has hepatitis B

- people who inject illegal drugs or share needles and syringes

- people with chronic liver disease

- people with end-stage kidney disease

- travelers planning to go to an area of the world with a high hepatitis B infection rate

ADULTS LIVING WITH HEPATITIS B

Testing positive for the hepatitis B virus for >6 months indicates having a chronic hepatitis B infection. All patients with chronic hepatitis B infections, including children and adults, should be monitored regularly, since they are at increased risk for developing cirrhosis, liver failure, or liver cancer.   

An appointment should be made with a hepatologist (liver specialist) or gastroenterologist familiar with hepatitis B. This specialist will order blood tests and possibly a liver ultrasound to evaluate hepatitis B status and the health of the liver. The doctor will probably want to see the patient at least once or twice a year to monitor hepatitis B and to determine if there would be benefit from treatment.   

Not everyone who tests positive for HBV will require medication. Depending on the test results, the doctor might decide to wait and monitor the condition. Whether starting treatment right away or not, the doctor will want to see the patient every six months, or at minimum once every year.

Once diagnosed with chronic hepatitis B, the virus will most likely stay in the blood and liver for a lifetime. It is important to know that one can pass the virus along to others, even if not feeling sick. This is why it's so important making sure that all close household contacts and sex partners are tested and vaccinated against hepatitis B. 

The most important thing to remember is that chronic hepatitis B is a medical condition as serious as diabetes and high blood pressure that can be successfully managed if you take good care of your health and your liver. You should expect to live a long, full life. 

HEPATITIS C VIRUS - detection from blood

HEPATITIS C VIRUS (HCV) 

KEY FACTS AND OVERVIEW:

Hepatitis C is a liver infection caused by the hepatitis C virus (HCV) and spread through contact with blood from an infected person; sometimes leads to serious liver damage. Nowadays, most people become infected with HCV by sharing needles or other equipment used to prepare and inject drugs. People may also get HCV from unsafe health care, unscreened blood transfusions and sexual practices that lead to blood exposure. 

    For some people, hepatitis C is a short-term illness, but for more than half of people who become infected with the HCV, it becomes a long-term, chronic infection. Long-term infection with the HCV is known as chronic hepatitis C and this can result in serious, even life-threatening health problems like cirrhosis and liver cancer. Antiviral medicines can cure >95% of people with HCV infection, but access to diagnosis and treatment is low. There is currently no effective vaccine against hepatitis C. Globally, an estimated 58 million people have HCV infection, with about 1.5 million new infections occurring per year. There are an estimated 3.2 million adolescents and children with chronic HCV infection.

    The best way to prevent hepatitis C is by avoiding behaviors that can spread the disease, especially injecting drugs. Getting tested for hepatitis C is important, because treatments can cure most people with hepatitis C in 8-12 weeks. 

SYMPTOMS:

The incubation HCV period: 2 weeks to 6 months. Following initial infection, approximately 80% of people do not exhibit any symptoms. People with chronic hepatitis C can often have no symptoms and don't feel sick, as chronic hepatitis C is usually a "silent" infection for many years, until the virus damages the liver enough to cause the signs and symptoms of liver disease. 

Signs and symptoms include: 

- bleeding and bruising easily

- fatigue and poor appetite

- yellow discoloration of the skin and eyes (jaundice)

- dark-colored urine

- itchy skin and weight loss, swelling in the legs

- fluid buildup in the abdomen (ascites)

- confusion, drowsiness and slurred speech (hepatic encephalopathy)

- spiderlike blood vessels on the skin (spider angiomas)

    HCV causes both acute and chronic infection. Acute HCV infections are usually asymptomatic and most do not lead to a life-threatening disease. Every chronic hepatitis C infection starts with an acute phase. Acute hepatitis C usually goes undiagnosed because it rarely causes symptoms. However, those who are acutely symptomatic may exhibit fever, fatigue, decreased appetite, nausea, vomiting, abdominal pain, dark urine, pale faeces, joint pain and jaundice. Acute symptoms appear at 1-3 months after exposure and last 2 weeks to 3 months.

    Acute HCV infection doesn't always become chronic. Of those with chronic HCV infection, the risk of cirrhosis ranges from 15% to 30% within 20 years.

CAUSES: 

Hepatitis C infection is caused by the HCV and spreads when blood contaminated with the virus enters the bloodstream of an uninfected person. 

Globally, HCV exists in several distinct forms, known as genotypes. Seven distinct HCV genotypes and more than 67 subtypes have been identified. The most common HCV genotype in the United States is type 1. Although chronic hepatitis C follows a similar course regardless of the genotype of the infecting virus, treatment recommendations vary depending on the viral genotype.

COMPLICATIONS:

HCV infection that continues over many years can cause significant complications, such as:  

- Scarring of the liver (cirrhosis). After decades of HCV infection, cirrhosis may occur. Scarring in your liver makes it difficult for your liver to function.

- Liver cancer. A small number of people with HCV infection may develop liver cancer. 

- Liver failure. Advanced cirrhosis may cause your liver to stop functioning.

GEOGRAPHICAL DISTRIBUTION:

HCV infections may occur in all regions. The highest burden of disease is in the Eastern Mediterranean and European Regions, as well as the South-East Asia and the Western Pacific Regions. Millions of people are chronically infected in the African Region and a couple millions also in the Region of the Americas. 

TRANSMISSION:

The HCV is a bloodborne virus, commonly transmitted through: 

- the reuse or inadequate sterilization of medical equipment, especially syringes and needles in healthcare settings;

- the transfusion of unscreened blood and blood products;

- injecting drug use through the sharing of injection equipment.

HCV can be passed from an infected mother to her baby and via sexual practices that lead to exposure to blood (for example, people with multiple sexual partners and among men who have sex with men).

Hepatitis C is not spread through breast milk, food, water or casual contact such as hugging, kissing and sharing food or drinks with an infected person.

TESTING AND DIAGNOSIS:

Because new HCV infections are usually asymptomatic, few people are diagnosed when the infection is recent. In those who develop chronic HCV infection, this is often undiagnosed because it remains asymptomatic until decades after infection when symptoms develop secondary to serious liver damage. 

HCV infection is diagnosed in 2 steps:

1. Testing for anti-HCV antibodies with a serological test identifies people who have been infected with the virus. 

2. If the test is positive for anti-HCV antibodies, a nucleic acid test for HCV ribonucleic acid (RNA) is needed to confirm chronic infection and the need for treatment. This test is important because about 30% of people infected with HCV spontaneously clear the infection by a strong immune response without the need for treatment. Although no longer infected, they will still test positive for anti-HCV antibodies. This nucleic acid for HCV RNA can either be done in a lab or using a simple point-of-care machine in the clinic. 

RT-PCR COUNTING HCV RNA IS THE MOST ACCURATE INFECTION INDICATOR.

After chronic HCV infection diagnosis, an assessment determines the degree of liver damage (fibrosis and cirrhosis). This can be done by liver biopsy or through a variety of non-invasive tests. The degree of liver damage is used to guide treatment decisions and disease management.

About 6.2% of the estimated number of people living with HIV globally have serological evidence of past or present HCV infection. Chronic liver disease represents a major cause of morbidity and mortality among people living with HIV globally.  

TREATMENT: 

A new infection with HCV does not always require treatment, as the immune response in some people will clear the infection. However, when HCV infection becomes chronic, treatment is necessary. 

WHO recommends therapy with pan-genotypic direct-acting antivirals (DAAs) for all adults, adolescents and children <3 years old with chronic HCV infection. DAAs can cure most people with HCV infection, and treatment duration is short (usually 12-24 weeks), depending on the absence/presence of cirrhosis. In 2022, WHO included new recommendation for treatment of adolescents and children using the same pan-genotypic treatments used for adults. 

 

Pan-genotypic DAAs remain expensive in many high- and upper-middle-income countries. Generic versions of these medicines have been introduced. The most widely used and low-cost pan-genotypic DAA regimen is sofosbuvir and daclatasvir.

Access to HCV treatment is improving but remains too limited. Of the million of people living with HCV infection globally, only an estimated 21% know their diagnosis, and of those diagnosed with chronic HCV infection, around 62% are treated with DAAs. 

PREVENTION:

There is no effective vaccine against hepatitis C so prevention depends on reducing the risk of exposure. 

Primary prevention interventions recommended by WHO include: 

- safe and appropriate use of health care injections;

- safe handling and disposal of sharps and waste (raised caution regarding body piercing and tatooing);

- provision of comprehensive harm-reduction services to people who inject drugs;

- testing of donated blood for HBV and HCV (as well as HIV and syphilis);

- training of health personnel; and

- prevention of exposure to blood during sex.

HEPATITIS D VIRUS - detection from blood

HEPATITIS D VIRUS (HDV) 

KEY FACTS AND OVERVIEW:

Hepatitis D virus (HDV) requires hepatitis B virus (HBV) for its replication; it affects around 5% of chronic HBV infected people. 

Indigenous populations, recipients of haemodialysis and people who inject drugs are more likely to have HBV and HDV co-infection. Since 1980s,  successful global HBV vaccination coincided with decreased HDV infection worldwide. 

The combination of HDV and HBV infection is considered the most severe  form of chronic viral hepatitis due to more rapid progression towards liver-related death and hepatocellular carcinoma and liver-related death. Hepatitis D infection can be prevented by hepatitis B immunization, but treatment success rates are low.  

Hepatitis D: liver inflammation caused by HDV. Vaccination against hepatitis B: the only prevention method.  

GEOGRAPHICAL DISTRIBUTION:

Geographical hotspots of high HDV infection prevalence: Mongolia, the Republic of Moldova, countries in western and central Africa. 

TRANSMISSION:

The routes of HDV transmission, like HBV, occur through broken skin (via injection, tattooing etc.) or through contact with infected blood or blood products. Transmission from mother to child is rare. Vaccination against HBV prevents HDV coinfection and hence expansion of childhood HBV immunization programs has resulted in a decline in hepatitis D incidence worldwide.

Chronic HBV carriers are at risk of infection with HDV. People who are not immune to HBV (either by natural disease or immunization with the hepatitis B vaccine) are at risk of infection with HBV, which puts them at risk of HDV infection.

Those who are more likely to have HBV and HDV co-infection include indigenous people, people who inject drugs and people with hepatitis C virus or HIV infection. The risk of co-infection also appears to be potentially higher in recipients of haemodialysis, men who have sex with men and commercial sex workers. 

SYMPTOMS:

In acute hepatitis, simultaneous infection with HBV and HDV can lead to signs and symptoms indistinguishable from those of other types of acute viral hepatitis infections: fever, fatigue, loss of appetite, nausea, vomiting, dark urine, pale-colored stools and jaundice (yellow eyes).

In a superinfection, HDV can infect a person already chronically infected with HBV. HDV superinfection accelerates progression to cirrhosis almost a decade earlier than HBV mono-infected persons. Patients with HDV induced cirrhosis are at an increased risk of hepatocellular carcinoma.

DIAGNOSIS:

HDV infection is diagnosed by high levels of anti-HDV immunoglobulin G (IgG) and immunoglobulin M (IgM), and confirmed by detection of HDV RNA in serum. However, HDV diagnostics are not widely available. 

TREATMENT:

Pegylated interferon alpha is the generally recommended treatment for HDV infection. The virus tends to give a low rate of response to the treatment, however, the treatment is associated with a lower likelihood of disease progression. This treatment is associated with significant side effects and should not be given to patients with decompensated cirrhosis, active psychiatric conditions and autoimmune diseases.

PREVENTION:

While WHO does not have specific recommendations on hepatitis D, prevention of HBV transmission through hepatitis B immunization, including a timely birth dose, additional antiviral prophylaxis for eligible pregnant women, blood safety, safe injection practices in health care settings and harm reduction services with clean needles and syringes are effective in preventing HDV transmission. Hepatitis B immunization does not provide protection against HDV for those already infected with HBV.

HEPATITIS E VIRUS - detection from blood

HEPATITIS E VIRUS (HEV)

KEY FACTS:

HEV infection causes inflammation of the liver. 

Transmission: fecal-oral route, especially contaminated water. HEV: found worldwide; most common East and South Asia. 

OVERVIEW:

HEV has 4 different types: genotypes 1, 2, 3 and 4. Genotypes 1 and 2: only in humans; genotypes 3 and 4: in pigs, wild boars and deer without causing any disease, and occasionally infect humans. 

The virus: shed in the stools of infected persons; enters the human body through the intestine. It is transmitted mainly through contaminated drinking water. The infection is usually self-limiting and resolves within 2-6 weeks. Occasionally leads to fulminant hepatitis (acute liver failure); it can be fatal. 

TRANSMISSION:

HEV infection is found worldwide, but common in low- and middle- income countries with limited access to essential water, sanitation, hygiene and health services. Here, it occurs both as outbreaks and as sporadic cases. The outbreaks follow periods of faecal contamination of drinking water supplies. Sporadic cases are also believed to be related to contamination of water, albeit at a smaller scale. The cases in these areas are caused mostly by infection with genotype 1 virus, and much less frequently by genotype 2 virus. In areas with better sanitation and water supply, HEV infection is infrequent, with only occasional sporadic cases. Most of these cases are caused by genotype 3 virus and are triggered by infection with virus originating in animals, usually through ingestion of undercooked animal meat.

SYMPTOMS:

Incubation period: 2-10 weeks (5-6 weeks average). The infected persons excrete the virus beginning from a few days before to 3-4 weeks after onset. Typical sings and symptoms: 

- initially: mild fever, reduced appetite (anorexia), nausea and vomiting (a few days);

- abdominal pain, itching, skin rash, or joint pain;

- jaundice, dark urine and pale stools;

- enlarged, tender liver (hepatomegaly)

These symptoms typically last 1-6 weeks. 

Rarely, acute hepatitis E can be severe and results in fulminant hepatitis (acute liver failure) - risk of death. Cases of chronic HEV infection: in immunosuppressed people, particularly organ transplant recipients on immunosuppressive drugs, with genotype 3 or 4 HEV infection (uncommon). 

DIAGNOSIS:

Hepatitis E cases: not clinically distinguishable from other acute viral hepatitis. However, diagnosis can often be strongly suspected when for example several cases occur in localities in known disease-endemic areas, in settings with risk of water contamination when the disease is more severe in pregnant women or if hepatitis A has been excluded. 

Definitive diagnosis of HEV infection is usually based on the detection of specific anti-HEV immunoglobulin M (IgM) antibodies in a person's blood. Rapid tests are available for field use. Additional tests: reverse transcriptase polymerase chain reaction (RT-PCR) to detect the HEV RNA in blood and stool.

TREATMENT:

As the disease is usually self-limiting, hospitalization is generally not required. Acetaminophen, paracetamol and medication against vomiting should be used sparingly. Hospitalization: required for fulminant hepatitis and symptomatic pregnant women. For immunosuppressed people with chronic hepatitis E: ribavirin treatment. In some specific situations, interferon has also been used successfully. 

PREVENTION:

At the population level, HEV transmission and infection  can be reduced by: 

- maintaining quality standards for public water supplies;

- establishing proper disposal systems for human faeces.

On an individual level, infection risk can be reduced by: 

- maintaining hygienic practices;

- avoiding consumption of water and ice of unknown purity.

SYPHILIS (treponema pallidum) - VDRL, RPR, TPHA; detection from blood and other fluids

Syphilis: bacterial STI caused by Treponema pallidum; results in substantial morbidity and mortality; transmission: sexual contact (majority) with infectious lesions of the mucous membranes/abraded skin, via blood transfusion, or transplacentally from a pregnant woman to her fetus. The genus Treponema belongs to the family Spirochaetaceae and has as a representative species Treponema pallidum, the etiological agent of syphilis. Treponema pallidum is a thin, tightly coiled spirochete (pallidum: subspecies).

On Treponema pallidum there is no gram staining, hence special staining and examination techniques are required for highlighting. It is microaerophilic and cannot grow on standard culture media. 

PATHOGENESIS:

Infection begins when T. pallidum penetrates the host, usually through intact or abraded mucous membranes; virulence factors: hemolysins, membrane proteins allowing for permeability of nutrients but inaccessible to antibody, ligands that allow cytoadhesion; the ensuing inflammation is responsible for most of the disease pathology. In the early disease, spirochetes can be found in the chancre, the usual first manifestation of syphilis. Invasion into the bloodstream and lymphatics occurs within hours to days of penetration of T. pallidum as evidenced by the fact that patients who received blood transfusions from syphilitic donors in the seronegative incubation period have become infected. All organs of the body can be invaded but the skin, lymph nodes, and the central nervous system (CNS) are the sites most often invaded. In the skin, T. pallidum is found in the dermal-epidermal junction zone or throughout the dermis. 

Both humoral and cell mediated immune responses are mounted against T. pallidum. At all stages of infection, there are local cellular infiltrates consisting of lymphocytes, macrophages, and plasma cells at the sites of disease. In primary syphilis, CD4+ T cells and macrophages are the predominate cell type while in secondary syphilis CD8+ cells predominate. In both primary and secondary syphilis, there is increased expression of TH1 cytokines IL-2 and IFN-Gamma. Cell mediated and humoral immune responses peak in secondary syphilis. Spirochetes may remain alive and continue to replicate in immunologically sequestered sites in the body even with a brisk initial immune response and no outward clinical manifestations of disease in at least 1 of 4 persons who are not treated. In late latent syphilis, after many years of latency, treponemes begin to multiple and Th1 lymphocytes produce high levels of nitric oxide and IL-12 instead of Il-2 and IFN. 

LABORATORY DIAGNOSIS: 

- bacteriological - microscopic examination; pathological products from patient;

- serological - changes in the patient's serum; most known: VDRL (Venereal Disease Research Laboratory), Bordet-Wassermann reaction (first blood test for syphilis, nontreponemal category; RPR and VDRL replaced it). 

T. pallidum lacks many pathways including the tricarboxylic acid cycle, components of oxidative phosphorylation and most biosynthetic pathways, and relies on the host to perform necessary functions.

Persons are most infectious early in disease when a chancre, mucous patch, or condyloma latum is present and by 4 years after acquiring the disease.  

Clinical manifestations: traditionally divided into five stages: incubating, primary, secondary, latent (early latent and late latent), and late or tertiary syphilis (neurosyphilis, cardiovascular syphilis and gummatous syphilis). 

Primary syphilis: 3 to 90 days (a median of 3 weeks) after infection. Single, painless chancre or ulcer develops at the site of inoculation. In some persons, it does not develop at all; in others, it is so small that it may go completely unnoticed. In those with HIV, multiple ulcers may develop. 

Secondary syphilis: widespread dissemination to various parts of the body. It becomes evident in a mean of 6 weeks after inoculation. In 90% of cases, there is a rash which most commonly is widely disseminated, maculopapular and involves the palms and soles but other dermatological manifestations are also common. Over 50% of cases have fever, malaise, anorexia, weight loss, pharyngitis, laryngitis, and/or arthralgias. Other manifestations: lesions in the mouth and oral cavity, lymphadenopathy, condyloma latum, glomerulonephritis, nephritic syndrome, hepatitis, arthritis, osteitis, and periosteitis.  

Latent syphilis is the period of months to years post infection in which there are no outward clinical manifestations of disease despite viable organisms. Clinical relapses can occur during the first year of the latent stage (referred to as the early latent phase), as a result of waning specific cellular immunity.  

Tertiary/late syphilis: in up to 35% of untreated patients 10 to 25 years after the initial infection. Can be categorized into: neurosyphilis, cardiovascular syphilis and granulomatous syphilis. The latter 2: uncommon in the antibiotic (frequent antibiotics' exposure); neurosyphilis: most common manifestation of tertiary/late syphilis nowadays (generally poor penetration of antibiotics into the CNS). 

A VARIETY OF LABORATORY TESTS HAVE BEEN DEVELOPED TO OVERCOME THE INABILITY TO CULTURE T. PALLIDUM USING STANDARD LABORATORY METHODS: 

• DIRECT DETECTION METHODS

- not widely available; false negative tests relatively common (30%). 

Dark Field Microscopy

- sensitive, direct, quick (in active lesions); specimens best obtained from serous transudate of moist lesions such as a primary chancre, condyloma latum or mucous patches (from dry skin or lymph nodes by non-bactericidal saline aspiration). 

- under dark field microscopy, T. pallidum will appear as corkscrew shape in spiraling motion with a 90° undulation about its midpoint (3 or more specimens required before deciding for non-syphilitic).

Polymerase chain reaction (PCR)

- can detect T. pallidum genetic material, most often the PoIA gene; most commonly used to detect congenital syphilis, but also effective for primary syphilis. 

Immunofluorescent and Immunoperoxidase Antibody Staining

- can be used to visualize nonviable spirochetes, from mucocutaneous lesions, lymph nodes, dry skin. 

• SEROLOGICAL TESTS

Nontreponemal Reaginic Antibody Tests

Syphilis reaginic antibodies are IgG and IgM antibodies directed against a lipoidal antigen resulting from the interaction of host tissues with T. pallidum or from T. pallidum itself. VDRL slide test: first nontreponemal test developed; except for its use in diagnosing neurosyphilis, it has now been largely replaced by the modifications such as the rapid plasma reagin (RPR) card test, automated reagin test (ART). 

Nontreponemal tests become positive shortly after initial infection, peak during the secondary or early latent stage, and then decline with time. In primary syphilis, an antibody response may not yet have been generated so nontreponemal tests may be negative. In secondary syphilis, virtually 100% of infected persons have positive serological tests for syphilis but in some patients the titers are so high that the test is reported as negative due to the prozone phenomenon. On the other hand, whenever there is a strong immunologic stimulus (e.g. acute bacterial or viral infection, vaccination, HIV infection), a "false" positive occurs. In addition, persons who use injection drugs, have autoimmune or connective tissue diseases (especially systemic lupus erythematosus), or hypergammaglobulinemic states may have "false" positive results. These persons often also have blood tests positive for other factors frequently associated with autoimmune disease such as antinuclear, antithyroid, or antimitochondrial antibodies; rheumatoid factor; and cryoglobulins. A negative specific treponemal test will confirm that the test is a false positive and that syphilis can be excluded.

Fluorescent Treponemal Antibody-Absorption (FTA-abs)

- uses T. pallidum harvested from rabbit testes as the antigen in a standard indirect immunofluorescent antibody test; confirms/refutes a positive nontreponemal test. At high suspicion, diagnoses syphilis even when a nontreponemal test is negative. 

T. pallidum Haemagglutination Assay (TPHA) and Microhemagglutination Assay for Antibodies to T. pallidum (MHATP)

- TPHA measures specific treponemal antibody;  performed easier than the FTA-abs and as specific, but not as sensitive, especially in early disease; 

- MHATP is similar to TPHA, except it uses a microtiter plate; "sorbent" is always used to increase its specificity.  

Enzyme-linked Immunosorbent Assay (ELISA) 

- immunoassay detecting T. pallidum specific antibodies; may detect only IgG or IgM but most assays are polyvalent. As with all ELISAs, an enzyme is conjugated with anti-human antibodies and only those wells that contain T. pallidum specific antibodies conjugated to the enzyme will exhibit a color change.  The sensitivity and specificity of ELISAs are similar to TPHA and FTA-Abs. Compared with the RPR and MHATP sensitivities, ELISA is more sensitive in all stages of syphilis except in secondary syphilis when all tests show 100% sensitivity.

Immunochromatographic Membrane Test (ICT)

- rapid test detecting T. pallidum antibodies employing anti-human immunoglobulins gold conjugate and highly purified TP recombinant proteins bound to a membrane; advantage over ELISA: it is visually read and can be performed at the point of care. 

Immunochromatographic Strip (ICS)

- a "lateral flow" test in which antibodies in a specimen are detected by becoming bound to antigens, marked with dye, on a cellulose strip; like ICTs, it requires no special training to read, laboratory equipment to run, or refrigeration of reagents or samples. 

Line immunoassay (LIA)

- uses recombinant and synthetic polypeptide antigens derived from T. pallidum proteins to determine if a clinical specimen has treponemal antibodies; like ICTs and the ICS test, it is inexpensive, rapid, and requires no special laboratory equipment or highly trained personnel.

INDICATIONS FOR LUMBAR PUNCTURE:

- any patient with symptoms and/or signs of neurologic or ophthalmic disease should have an evaluation that includes CSF analysis, ophthalmologic examination and otologic evaluation; 

- patients whose symptoms and/or signs persist posttreatment for early syphilis or recur or who have four-fold increases in their NTA titers should be considered to be treatment failures or re-infected and all should have a lumbar puncture. Patients with latent syphilis who meet any of the following three criteria also should have lumbar punctures: patients whose symptoms and/or signs persist posttreatment for early syphilis or recur or who have four-fold increases in their NTA titers should be considered to be treatment failures or re-infected and all should have a lumbar puncture;

Changes consistent with syphilis in the CSF include the following:

- an elevated cell count usually of less than 200 cells predominantly lymphocytes

- elevated protein up to 200 mg/dL

- normal glucose in the majority of patients though it may be modestly decreased in about a third positive NTA test (TSAs are not used for the diagnosis of central nervous system syphilis)

Patients with abnormal spinal fluid results should have repeat studies performed at 6 month intervals until the cell count is normal. Elevated protein levels and the CSF NTA antibody titer may take longer to resolve and are not important as long as the CSF cell count returns to normal. 

If cell counts have not returned to normal by 2 years the patient should be re-treated. 

Keep in mind that HIV infection causes CSF pleocytosis and elevated protein levels independent of syphilis and this may be an explanation for nonresolution of CSF abnormalities in such persons.

TESTING ALGORITHMS FOR SYPHILIS IN ADULTS EXCEPT NEUROSYPHILIS

Diagnosing syphilis algorithm: nontreponemal test; if reactive, verify with FTA-abs, TPHA, MHATP, or ELISA. If both tests are reactive, then a person is considered to have present or past syphilis infection. Treatment decisions are based on past history and nontreponemal titers. 

As with the traditional method, when a person is reactive to both a specific treponemal such as a positive ELISA test and nontreponemal test such as a RPR, then a person is considered to have active disease requiring treatment. When a person is reactive to the treponemal test but nonreactive to the nontreponemal test such as a RPR test, persons with a history of previous treatment will require non further management. Those with no prior history of treatment should have a different treponemal test performed such as an FTA-abs. If the second test is also nonreactive, then the clinician needs to use his/her clinical judgement to decide whether or not a third treponemal test is indicated.

TESTING ALGORITHMS FOR CONGENITAL SYPHILIS

The diagnosis for congenital syphilis is best made by testing the mother at the time of birth since infant serum titers, even when the infant is infected, may be non-reactive, especially if the mother has low titers or the mother was infected late in pregnancy. If the mother has reactive syphilis serology, then the infant's serum should be evaluated with a RPR or VDRL. Infants should also have a physical exam and dark field microscopy or direct fluorescent staining of any suspicious lesions and radiological and ultrasound studies. The placenta or umbilical cord should also be examined using specific fluorescent anti-treponemal antibody staining. IgM-specific antibodies (ELISA, reverse enzyme-linked immunospot (Relispot), FTA-abs, or immunoblotting/Western blot) and PCR are also recommended to make the diagnosis. 

TESTING ALGORITHMS FOR NEUROSYPHILIS

A lumbar puncture with the CSF sent for VDRL, cytology, and protein is the most commonly used method for making the diagnosis. A reactive CSF-VDRL is considered diagnostic of syphilis while a negative test does not rule out disease, e.g., it is a specific but not very sensitive test. If the CSF-VDRL is negative, a finding of >5 mononuclear cells per cubic millimeter, a protein value of ≥46 mg/dL, or a glucose of ≤45 mg/dL, all suggest neurosyphilis.  

Methods with greater sensitivity and specificity than the CSF-VDRL are the intrathecal T. pallidum antibody (ITPA) and TPHA. A FTA-abs test is usually not performed on CSF because a positive test may represent passive transfer of antibody from serum to the CSF and not active CNS disease. However, it is highly sensitive and thus a negative test can be helpful in ruling out neurosyphilis, especially in HIV infected patients who often have white blood cells in the CSF.  

SUSCEPTIBILITY IN VITRO AND IN VIVO

Penicillin, the first antibiotic developed, was the first known effective antibiotic for T. pallidum and remains the treatment of choice today. T. pallidum can regenerate if the serum penicillin concentration falls to sub-inhibitory levels for 24-30 hours.

T. pallidum is also susceptible to virtually all other β-lactam antibiotics (amoxicillin, ceftriaxone, ceftizoxime, cefmetazole, cefetamet). Macrolide antibiotics are also able to inhibit T. pallidum but not as efficiently as the β-lactam antibiotics. 

Combination therapy for syphilis is no more efficacious than single drug therapy. The addition of amoxicillin and probenecid for 10 days to 2.4 million units of penicillin achieves similar result as penicillin alone. 

CLINICAL PRESENTATION OF SYPHILIS

- can mainly be divided into early syphilis and late syphilis.

EARLY SYPHILIS

- primary syphilis: the primary ulcer or chancre: on the genitals, perianal skin, within the rectum, oral cavity, and any other skin or mucous membrane surface exposed to an infectious lesion that was present on the source sexual partner. The average incubation period is 3 weeks but can vary from 10 to 90 days. Any genital ulcer should be considered to be syphilis until proven otherwise. The lesions of primary syphilis will resolve within 3 to 6 weeks without treatment. Of course, the individual remains infected and will become infectious again with the advent of secondary syphilis. 

- secondary syphilis: left untreated, the organism disseminates hematogenously from the site of the primary infection to all parts of the body. This occurs within a few weeks or months of the onset of the primary lesions. Cutaneous and/or mucous membrane lesions are the most common clinical manifestations of the phenomenon and occasionally the primary lesion persists.  

Initially erythematous macules which evolve into hyperpigmented papules. Skin lesions are usually present on both the palms and soles and any rash with this distribution should immediately bring secondary syphilis to mind. Mucosal lesions are generally superficial, ulcerated, and painless with gray borders. Similar lesions may be found on the foreskin, penile head, and intravaginally. Patchy alopecia can be a manifestation of scalp involvement in secondary syphilis. Low grade fever, malaise, headache, and generalized lymphadenopathy often accompany dissemination.  

Uncommon systemic manifestations of secondary syphilis include gastritis, mild hepatitis, and aseptic meningitis. As with the primary chancre, the manifestations of secondary syphilis also will resolve spontaneously over time but over a period of a few years there may be relapses of secondary disease.

- EARLY LATENT SYPHILIS: asymptomatic person with a normal physical examination who is diagnosed serologically and has a history of syphilis exposure within the preceding 1 year.

LATE SYPHILIS

- neurosyphilis 

Persons who have syphilis and symptoms or signs suggesting neurologic or ophthalmic disease should have an evaluation that includes CSF analysis, ocular slit-lamp ophthalmologic examination, and otologic examination. 

Acute syphilitic meningitis: The incubation period for this relatively rare syndrome is usually less than 1 year; treatment is the same as for late disease. Symptoms and signs of meningitis are the first clinical manifestations in only a quarter of patients.

In some of these patients the cerebrospinal fluid (CSF) examination is normal, particularly those with isolated 8th nerve disease, though the majority have modestly elevated cell counts, increased protein, and positive CSF serologic tests or a combination of these results. 

Cerebrovascular syphilis: incubation period is 5 to 12 years after the initial infection. The most common manifestations are hemiparesis or hemiplegia. It affects the middle and anterior cerebral arteries most frequently. Other presenting problems include aphasia and seizures. 

Neurosyphilis should be strongly suspected in all younger patients presenting with cerebrovascular accidents. 

Ocular syphilis: have been reported increasingly; most suspected cases in males, half in HIV-positive persons. A significant proportion of cases have been reported in patients with early syphilis. Severe outcomes, including blindness, have been reported in both HIV-positive and negative patients.  

All patients diagnosed with syphilis that exhibit ocular manifestations should immediately be treated for neurosyphilis and be referred for formal ophthalmologic examination. Optic atrophy in the absence of signs of inflammation may be found in association with other manifestations of neurosyphilis or may be an isolated finding of late syphilis. 

Nonneurologic manifestations of late syphilis (tertiary syphilis): various cardiovascular diseases. Late benign syphilis lesions or gummas are rarely seen today. 

What laboratory tests should you order and what should expect to find?

- A dark field examination of fluid expressed directly from a lesion in the time-honored diagnostic test for patients with the skin lesions of primary and secondary syphilis; the specimen is obtained by pressing a glass slide directly onto a lesion and then placing it immediately under a darkfield microscope for reading.  

Serologic tests are the cornerstone of syphilis diagnosis. There are two general types of tests: 

The reagin or nontreponemal assays (NTAs) is based on the fact that human antibodies induced by T. pallidum infection cross react with mammalian cardiolipin. In essence this is an "autoantibody" and therefore it is not too surprising that it lacks specificity. Conditions associated with false positive NTAs include old age, pregnancy, malignancy, and collagen vascular disease among others. The advantage of NTAs is the rise and fall of antibody titers reflect the course of disease including decreasing titers in patients who have been successfully treated. A four-fold reduction in titer over a period of 3 to 12 months is accepted as evidence of treatment success. An additional advantage is that one of the NTAs, the rapid plasma reagin (RPR) card agglutination test, is relatively quick and simple to perform.

The treponeme specific assays (TSAs) traditionally have been used to confirm that a positive NTA is a true positive test. Following this algorithm when a syphilis serology is ordered on a patient the laboratory first performs a NTA and if positive then automatically performs a TSA test to differentiate between a true and a false positive NTA result. The TSAs generally are more complex tests and take more time so in the case of a negative NTA they are not performed. 

Interpretation of syphilis serologic assays following the traditional testing algorithm: neither a negative NTA nor negative TSA rules out primary syphilis. It follows then that in a patient suspected of having a primary chancre, if the RPR is negative the patient should be treated for primary syphilis empirically. Such patients can be invited to return to the clinic in several weeks to determine if seroconversion has occurred. In contrast to primary syphilis, a negative NTA almost does rule out secondary syphilis. Over a period of years following an untreated primary infection, the NTA test will become negative in a proportion of patients with late syphilis while the TSA remains positive in almost all cases. Therefore, if an NTA is negative in a patient suspected clinically of having late syphilis the care provider should order a TSA. Remember that the laboratory only performs this test automatically if the NTA is positive.

List of available serologic tests for syphilis (top below) and expected results of serologic testing in patients with untreated syphilis (bottom below):

  

TESTING GUIDELINES - SUMMARY:

TREPONEMA PALLIDUM (SYPHILIS) SCREENING CASCADE: