bilharzia

Bilharzia: description

The causative agent of schistosomiasis (Schistosomiasis) is the pairing (Schistosoma). That’s the name of it, because it always requires a male and a female to propagate in order to close the infection cycle. The worms live in the blood vessels of the human abdomen and excrete their eggs over the feces or urine of the infected.

There are different species of the parakeet, which can cause a different disease depending on the country and species. The most common schistosomiasis pathogens are:

• Schistosoma haematobium: Africa, Orient and India
• Schistosoma mansoni: Africa, Orient, South / Central America
• Schistosoma mekongi: Southeast Asia
• Schistosoma japonicum: East Asia
• Schistosoma intercalatum: Central Africa

According to estimates of the World Health Organization WHO are approximately 200 million people infected with schistosomes worldwide. Every year, around 200,000 people die as a result of schistosomiasis, most of them in Africa. Due to the growing tourism in sub-Saharan countries (eg Egypt), the infection areas are widening. Since schistosomiasis can cause severe health problems, a visit to the doctor should always be carried out after a tropical journey with appropriate symptoms.

Bilharzia: life cycle of the parasite

The malady is usually not caused by the couple’s own gel, but by the eggs, which migrate through the tissue, to then be excreted by humans. If the eggs get into the fresh water, they develop further. There larvae hatch from the eggs (miracidia) nesting in a certain type of freshwater snail. Thousands of cercarialthat get back into the water from where they can attack humans. If a person bathes in the infected water, or wades through a swamp area, there is the possibility of an infection. At the same time the head of the cercaria penetrates the skin, and the tail is repelled.

It takes about two days for them to adapt to the human organism and travel to the lungs via the venous system. After some stages of development, the schistosomes reach the blood vessels of the liver. There it comes to the pairing of the couple’s angel. Most schistosomiasis pathogens use the intestine to lay down their eggs, some of them too bladder, For this they migrate into the corresponding vascular network of the organ.

It takes at least a good week from infestation of the skin until the couple’s wings have formed. Egg production starts about six to eight weeks later, Schistosomes can produce several hundred to a thousand eggs a day. To allow the eggs to enter the intestine or bladder, they slowly fester on the intestinal / bladder wall. This process is often accompanied by a strong immune reaction. In many cases, this is the time when the patient first experiences symptoms of schistosomiasis.

What is the World Health Organization (WHO) doing against schistosomiasis?

The WHO is trying to prevent the spread of schistosomiasis by targeted treatment of risk groups. If a certain number of people in a place or region are infected, they will all be treated as a precaution in the village or community. Between 2011 and 2014, more than 42 million people received bilharzia therapy.

Bilharzia: symptoms

Bilharziosis causes acute symptoms within hours and days. If the schistosomiasis is not recognized and the treatment stays off, the couples’ eggs cause great damage in the human body, leading to so-called chronic schistosomiasis.

Symptoms of acute schistosomiasis

The first symptoms of schistosomiasis occur only a few hours after contact with the contaminated water. After the larvae of the pair of leeches have penetrated into the skin, there is a skin reaction at the entry points, the to a allergic rash reminds (cremate dermatitis). Acute schistosomiasis may also be accompanied by fever. The temperature increase occurs several days to weeks after infection. Fever caused by schistosomiasis is called Katayama fever, Typically, the fever is accompanied by cough, chills and headache. These symptoms are often misjudged as a flu infection, so that the schistosomiasis infection remains untreated in most cases.

After several weeks, the worms are sexually mature and lay their eggs in the intestinal wall. It comes to low-viscosity chairs with small blood enemas. The worm species S. haematobium shows through a Blood in the urinebecause the eggs are placed in the bladder wall.

Symptoms of chronic schistosomiasis

The schistosomes can survive for years in the vessels in the abdomen and cause great damage especially with their eggs. Because even if cercaria and worms cause a certain immune response, it is mainly the eggs that trigger a tremendous immune response. In doing so, the organs involved take on large and mostly irreparable damage. Generally, one differentiates between two different types of schistosomiasis:

Bilharzia of the bladder (urogenital bilharzia): In S. haematobium the eggs are deposited in the bladder wall. The immune reaction causes bleeding and scarring in the bladder wall. Patients often report pain in urination and blood in the urine. In 60 percent of those affected by this form of schistosomiasis there is also an involvement of the genital tract. In women, the fallopian tubes stick together, it comes increasingly to infertility. Especially dreaded is the risk that an embryo will become lodged in the abdominal cavity instead of the uterus (extrauterine pregnancy). This complication can lead to life-threatening bleeding, and is therefore an emergency.

Due to the damage to the bladder and the ureter, urinary tract infections are more common since bacteria can more easily colonize the bladder wall. In addition, the ongoing battle between the immune system and schistosom eggs can cause malignant degeneration of bladder tissue.

Bilharzia of the intestineIn the schistosomiasis of the intestine, the couple ‘s eggs lay the eggs in the intestinal wall, which they slowly penetrate until they are then eliminated with the stool. Often it comes to abdominal pain and recurrent diarrhea with blood admixtures. The ongoing blood loss can even lead to anemia (anemia), which is shown by paleness and fatigue in the patient. Since the intestine has many small injuries due to the migrating eggs, scarring is also possible here, and thus a certain loss of mucous membrane function. Unfortunately, the vacancies also serve other organisms such as Salmonella as a portal of entry into the body, making it more susceptible to infection.

Strong infestation with schistosomiasis

In a severe attack with schistosomes so many eggs are placed in the plexus of the bladder or the intestine, that some eggs also get into the liver, spleen, brain or lungs. If this happens, the immune system also tries to eliminate the parasite eggs in these organs. The organs are severely damaged.

Complex symptoms, such as a slowly worsening shortness of breath or shortness of breath could be evidence of a pulmonary fibrosis be. A slow yellowing of the skin is often caused by a limited liver function it can even cause liver failure to lead. The symptoms that can be caused by the severe attack of schistosomiasis, are diverse and must be associated with the malfunction of the corresponding organ system.

Since schistosomiasis in addition to the organ damage and the blood circulation of the organs is disturbed, it can be to the Change in pressure conditions come. If many pairs of worms live in the vessels of the abdomen, the blood can no longer flow back to the heart as usual via the liver. If this happens, bleeding threatens, for example, in the esophagus or rectum. Bloody vomiting, coughing, or bright red blood in the stool are symptoms that may alert to such complications. In order to avoid such life-threatening consequences of schistosomiasis, therapy is indispensable.

Bilharzia: causes and risk factors

Bilharzia infection occurs in stagnant freshwater in tropical countries. It poses a major problem: more than 200 million people worldwide are infected. Especially children and young adults are at risk as they come into greater contact with rivers and lakes. Before each tropical trip you should discuss the country-specific risks with a tropical medicine. As 76 countries worldwide are affected, you should generally avoid contact with freshwater in these countries.

Bilharzia: examinations and diagnosis

If you suspect you have bilharzia, it is best to go to a tropical medicine or gastroenterologist. This will first lead a conversation with you (anamnese). He could ask the following questions:

• Have you been in the tropics lately?
• Did you bathe there in inland waters?
• Did you have a rash recently?
• Do you have fever?
• Do you suffer from diarrhea and / or abdominal pain?
• Is blood visible in your urine?
• Do you have pain when urinating?

Also, you should educate the doctor about his risk behavior in the respective country. This is followed by the physical examination, If the doctor scans the abdomen, he can often feel an enlarged liver, spleen and swollen lymph nodes suspected in schistosomiasis. As a rule, further diagnostic measures are then considered.

Possible investigations

Which exactly is used by the doctor depends on the stage of schistosomiasis. Already in the first weeks of infection can be with the help of a blood tests recognize a strong change in a group of white blood cells (eosinophilia). With the help of an antibody test, it can be proven whether the immune system already had contact with cercaria, suggesting schistosomiasis. A few weeks later are the eggs directly in the stool or in the urine detectable. Sometimes you can even put the worms in the body radiological images to make visible. A ultrasound and a Colon / cystoscopy can often give additional information on the extent of the organ damage, and thus substantiate the suspicion of schistosomiasis.

In a long-term infection, it may be due to the immune reaction in the various tissues too Calcification and scarring (Fibrosis) come. These changes can be so pronounced that they can be recognized on an x-ray. Since it is usually possible to detect only very dense and hard materials such as bones on x-ray images, this suggests an already very advanced schistosomiasis.

Bilharzia: treatment

The treatment of schistosomiasis is relatively simple and is also used by the WHO in whole populations to limit the spread of the parasite. The unique gift of the drug praziquantel is sufficient in most cases. With his help, the muscles of the worm are paralyzed, so he dies. This stops further egg production and the patient no longer excretes any eggs. The infection cycle of schistosomiasis is interrupted.

However, there is also criticism of the therapy with praziquantel in schistosomiasis. The patient additionally suffers from another parasitic disease, the Neurocystizerkose, the drug can cause serious harm to the patient and even death. Generally, however, it is very well tolerated and has few side effects.

For severe symptoms, steroids such as cortisone may be needed in some cases to stop the immune response and not endanger the patient. This is sometimes the case in the initial stages of infection, for example, with severe Katayama fever.

Bilharzia: disease course and prognosis

The earlier a schistosomiasis is treated, the better. Many schistosomiasis infections are not noticed by patients for years and it comes only after years of organ damage for diagnosis. In order to avoid that, a precautionary investigation after a tropical journey is recommended in America, when in contact with freshwater.

The tropical disease is underestimated by many travelers, so that there are sometimes unrecognized sequelae of schistosomiasis in Europe. If the infection remains untreated for a long time, kidney, liver, lung, and heart failure, as well as disorders of many other tissues in the body threaten. Since many of these consequences can be fatal, the most rapid and consistent diagnosis and therapy is essential. Bladder rosiniosis increases the risk of bladder cancer. It usually occurs 10 to 20 years after the initial infection. During a pregnancy, the bilharzia also lead to complications.