Central African Republic

• Yellow fever occurs in sub-Saharan Africa and South America and is transmitted by mosquitoes.
• Disease may be severe in unvaccinated travelers and death may occur in over 50%.
• A highly effective vaccine is available.
• Due to potentially severe side effects the vaccine is used with caution in immunocompromised or elderly individuals, as well as in pregnant women.

As against all mosquito-borne diseases, prevention from mosquito bites is during day and night (see “Insect and tick bite protection” factsheet). The available vaccine is highly efficacious and provides a long-term protection. It is recommended for people aged 9 months or older who are travelling to yellow fever endemic areas. In addition, providing proof of vaccination may be mandatory for entry into certain countries.

The vaccine is a live-attenuated form of the virus. In immunocompetent persons, protection starts about 10 days after the first vaccination. Reactions to yellow fever vaccine are generally mild and include headache, muscle aches, and low-grade fevers.  Side effects can be treated with paracetamol but aspirin and other nonsteroidal anti-inflammatory drugs, for example ibuprofen or naproxen, should be avoided.  On extremely rare occasions, people may develop severe, sometimes life-threatening reactions to the yellow fever vaccine – which is why this vaccine is used with caution in immunocompromised individuals, pregnant women and the elderly for safety reasons. Talk to your travel health advisor if you belong to this group.

• Hepatitis A is a liver infection caused by a virus.
• The virus is easily transmitted by contaminated food or water but can also be transmitted through sexual contact.
• A safe and very effective vaccine is available that affords long-lasting protection.
• Hepatitis A vaccination is recommended for all travelers going to tropical or subtropical countries, and for risk groups.

Hepatitis A occurs all over the world, but the risk of infection is higher in countries with poor hygiene standards. There is an increased risk in most tropical and subtropical countries, as well as in some countries in Eastern Europe and around the Mediterranean.

In recent years, there have also been increasing cases in North America and Europe, including Switzerland, especially among men who have sex with men (MSM). Outbreaks in northern European countries can also occur when unvaccinated children become infected during family visits to tropical and subtropical countries. Upon return, they may transmit the virus within their care facilities.

There is a safe and very effective vaccine that consists of two injections at least 6 months apart. It provides lifelong protection after the second dose. Hepatitis A vaccination can also be given in combination with hepatitis B vaccination (3 doses required).

Vaccination against hepatitis A is recommended for all travellers to risk areas, as well as for persons at increased personal risk: persons with chronic liver disease, men who have sex with men, people who use or inject drug, persons with increased occupational contact with persons from high-risk areas or populations, and others.

• Federal Office of Public Health (FOPH). Hepatitis A. https://www.bag.admin.ch/bag/en/home/krankheiten/krankheiten-im-ueberblick/hepatitis-a.html 
• Swiss Hepatitis: https://en.hepatitis-schweiz.ch/all-about-hepatitis/hepatitis-a 

• Polio is a vaccine-preventable viral disease of the nervous system that is acquired mainly through the consumption of food or water contaminated by feces.
• The infection with the polio virus can affect children and adults and may lead to permanent limb or respiratory muscle paralysis and death.
• An effective, well- tolerated vaccine is available! Check if booster doses are recommended for the travel destination (on top of completed basic vaccination schedule).

Regular hand washing after using the bathroom and before eating or preparing food. Avoidance of undercooked or raw food that is potentially contaminated with fecal material.

The most important prevention is vaccination. A very effective and well-tolerated vaccine against polio is available (inactivated (killed) polio vaccine (IPV)), which is part of the basic vaccination schedule during childhood. Combination vaccines (e.g. with diphtheria and tetanus) are also available. After basic vaccination, a booster dose is recommended every 10 years for travel to certain countries (see country page recommendations). WHO recommends a yearly vaccination for residents or long-stay visitors (minimum 4 weeks) in a country with ongoing polio infections or circulating vaccine-derived polio viruses. This recommendation not only targets individual protection, but aims to prevent the international spread of the virus.

WHO: https://www.who.int/news-room/fact-sheets/detail/poliomyelitis

FOPH Switzerland: Swiss vaccination plan: https://www.bag.admin.ch/bag/de/home/gesund-leben/gesundheitsfoerderung-und-praevention/impfungen-prophylaxe/schweizerischer-impfplan.html

• Rabies is mainly transmitted by dogs (and bats), but any mammal can be infectious.
  
• It is invariably fatal at the time when symptoms occur.
  
• Rabies is best prevented by a pre-travel vaccination and appropriate behavior towards mammals.
• Pre-travel vaccination is also recommended because vaccines and immunoglobulins are often not available in many travel countries. Vaccination before travel is highly recommended in particular for
  
  • long-term stay in endemic countries,
    
  • short journeys with high individual risk such as travellers on ‘two wheels’ or treks in remote areas, toddlers and children up to 8 years of age,
    
  • professionals working with animals, or cave explorers (bats!).
• Attention: a bite or scratch wound as well as contact with mammal saliva is an emergency! Find out about the necessary actions below!

No treatment against rabies disease exists.

Post-exposure measures:

• Immediate cleaning of the wound with plenty of water and soap for 10-15 minutes, followed by disinfection (e.g. Betadine, Merfen) and emergency post-exposure vaccination at the nearest health institution within 24 hours.
  
• Tetanus booster vaccination is also required.
  
• For those having received full pre-exposure rabies vaccination before travel: two additional vaccine shots (any available brand) at an interval of 3 days suffice.
  
• If full pre-exposure vaccination has not been given, in addition to vaccination, passive immunization is required with immunoglobulins.
  
• It should be noted that immunoglobins (and sometimes vaccines) are often unavailable in low-resource settings, causing stress and uncertainty.

Stroking cute pets is not a good idea; refrain from touching wild or unfamiliar or dead animals.
All travellers to places where rabies may occur and who are likely to take repeated trips to areas where rabies occurs should have a pre-exposure vaccination. In addition, pre-exposure vaccination is highly recommended for travellers at particular risk:

• long-term stay in endemic countries,
  
• short journeys with high individual risk such as travellers on ‘two wheels’ or treks in remote areas, toddlers and children up to 8 years of age,
  
• professionals working with animals, or cave explorers (bats!).
  

The shortened vaccination schedule can be proposed to most travellers: 2 shots, the first one at one month before departure if possible (minimum: 8 days before departure). A single third rabies booster vaccination is recommended before the next trip, at least after one year.

• Obtain information about prevention of rabies in time before travelling.
  
• In case of trips planned for longer than a few weeks, schedule a visit at the travel clinic 4 weeks before departure at the latest.
  
• After possible exposure (bite, scratch injury) wound treatment and additional vaccinations are necessary even for those with a completed series of basic vaccinations.
  
• This information leaflet should be printed and kept handy during the trip!

• FOPH Switzerland (German): https://www.bag.admin.ch/dam/bag/de/dokumente/mt/infektionskrankheiten/tollwut/bag-bulletin-15-2021-tollwut-prep-und-pep.pdf.download.pdf/210412_BAG_Bulletin_15_2021_Tollwut%20PrEP%20und%20PEP_d.pdf 
  
• FOPH Switzerland (French): https://www.bundespublikationen.admin.ch/cshop_mimes_bbl/14/1402EC7524F81EDBA5D6C3EBC18BA9FB.pdf 

• Typhoid fever, also called enteric fever, is caused by the bacteria Salmonella Typhi and Salmonella Paratyphi.
• Infected persons shed the bacteria in their feces. In countries with low sanitation standards, the bacteria can then enter the drinking water system and lead to infections in other people.
• Frequent sources of infection are contaminated food and beverages.
• The main preventive measure therefore is “cook it, peel it, boil it or forget it” – meaning: avoid drinking uncooked water or water from unsealed bottles; avoid cooled/frozen products (e.g. ice cubes in drinks, ice cream) unless from a known safe source; avoid uncooked vegetables, peel and clean fruit and vegetables yourself and only with known safe drinking water.
• A vaccine is available and recommended: a) for travelers to the Indian subcontinent or to West Africa, b) for travelers visiting friends and relatives or for long-term travelers also to other sub-/tropical areas.

“Cook it, boil it, peel it or forget it” – this simple slogan would be sufficient to prevent typhoid fever nearly entirely. However, only few travelers fully adhere to this advice. Nevertheless, the value of food and water hygiene cannot be stressed enough: avoid buying water bottles without proper sealing, avoid drinking tap water from unknown sources, avoid eating cooled / frozen foods (i.e. ice cubes in water or ice cream) and avoid eating raw fruits and vegetables that you yourself have not peeled and washed with clean drinking water.

Two types of vaccines are available:

• Oral (live) vaccine consisting of three capsules to be taken on alternate days on empty stomach. These capsules require refrigeration before use. Protection from this vaccine is approximately 70% and starts 10 days after the third dose. After 1 to 3 years, the vaccine needs to be taken again before a new travel into at-risk areas. This vaccine cannot be given to patients with a severe chronic gastrointestinal disease (such as Crohn’s disease or ulcerative colitis) or with severe immunosuppression.
• The single-dose vaccine is an inactivated vaccine and is injected intramuscularly. Protection also reaches around 70% and starts 14 days after the injection. This vaccine can be given to patients who should not take the oral vaccine. However, it is not registered in Switzerland, but most doctors with specialization in tropical and travel medicine and all travel health centres have the vaccine on stock. Duration of protection is around 3 years.

• Meningococcal disease is a very severe, life threatening bacterial infection that can lead to death within a few hours if untreated.
• Transmission occurs from person to person by droplets. The risk is higher for travelers to regions with seasonal epidemics (meningitis belt in sub-Saharan Africa).
• The disease can be prevented by one dose of four-valent meningococcal vaccine and protection lasts for at least 5 years.

Meningococcal vaccination is recommended in Switzerland as a complementary vaccination for children between 2 – 4 years and for adolescents between 11 – 15 years. Furthermore, it is recommended as a risk group vaccination for persons with certain medical conditions, for persons with close contact to a patient with meningococcal disease and for travelers to endemic areas.

For more detailed information on the disease and Swiss national recommendations (in German, French, Italian) see: https://www.bag.admin.ch/bag/de/home/krankheiten/krankheiten-im-ueberblick/meningokokken-erkrankungen.html

• Regions: Entire country.
  
  

Prevention: Mosquito bite prevention and chemoprophylaxis.
Discuss with your travel health advisor which prophylactic medication is suitable for you. The travel health advisor will prescribe the appropriate medication and dosage.

• Malaria is a life-threatening parasitic infection, which is transmitted by mosquitoes at night.
• Great care should be given to preventive mosquito protection from dusk to dawn in all malaria risk areas.
• In high-risk areas, the intake of prophylactic medication is strongly advised.
• For stays in low risk areas: discuss with a travel health advisor whether carrying an emergency self-treatment against malaria is necessary.
• If you belong to a special risk group (pregnant women, small children, senior citizens, persons with pre-existing conditions and/or with immune deficiency): seek medical advice before the trip as malaria can quickly become very severe.
• If you have a fever >37.5°C on axillary or tympanic measurement (a functioning thermometer is indispensable!) during or after the trip, see a doctor / hospital immediately and have a blood test done for malaria! This applies regardless of whether you have used prophylactic medication or not!

Fever during or after a stay in a malaria-endemic area is an emergency! Prompt diagnosis and treatment are required as the health of people with malaria can deteriorate very quickly. That means: if you have fever >37.5° (use a thermometer!) you need to test for malaria within a maximum time-frame of 24 hours, regardless of whether or not you have used prophylactic medication (malaria chemoprophylaxis). Try to reach a doctor or hospital where you can reliably receive such a test. If the first test is negative, it should be repeated on the following day if the fever persists.

Prevention of malaria requires a combination of approaches:

1. Diligent mosquito-bite protection at dusk and at night until dawn is of key importance. Use it for all regions where malaria is present, including areas where the risk is minimal. Bite protection is also effective against other insect-borne diseases that often occur in the same region. It consists of the following measures:
   • Clothing: Wear long-sleeved clothes and long trousers. For additional protection, impregnate the clothes beforehand with insecticides containing the active ingredient permethrin (e.g. Nobite® Textile).
   • Mosquito repellents: Apply a mosquito repellent to uncovered skin.
   • Sleeping room: Sleep in an air-conditioned room or under an impregnated mosquito net. Cautiously use ‘knockdown’ sprays indoors or burn mosquito coils strictly outside, e.g. under a table in the evening.
   • Chemoprophylaxis: Depending on the region and season, it may be necessary to take a prophylactic medication. This is recommended for all destinations with a high risk of malaria (marked as red on our maps). It needs to be taken with food before, during, and after your stay. Discuss with your travel health advisor to ascertain if you need to take chemoprophylaxis for your trip. The appropriate medication and the right dosage will be prescribed.
     
2. Taking standby emergency self-treatment (SBET, drugs used to self-treat malaria) with you is recommended for special risk situations (stay in regions with low malaria risk and if there is no or uncertain medical care available). Following such a course of SBET, please consult a doctor as soon as possible. Talk to your travel health advisor to determine whether carrying SBET is necessary, especially if you plan a trip where reliable medical infrastructure is not assured.
3. For some risk groups, malaria can quickly develop to a dangerous disease. If you are pregnant, if you are travelling with small children, or if you are a senior citizen and / or if you have other illnesses /pre-existing conditions and / or you are immunocompromised, you should seek advice from a specialist in travel medicine to determine whether chemoprophylaxis is recommended for your trip – even if the area is marked as low risk malaria zone.
   

For travellers, there is currently no malaria vaccination available.

• Take a functioning clinical thermometer with you!
• Malaria symptoms develop at the earliest 7 days after entering the malaria area. A fever > 37.5° always means suspicion of malaria!
• In case you have fever during or even months after a stay in a malaria area:
  • Immediately consult a health care facility to rule out malaria through a blood test.
  • This should be done within a maximum of 24 hours and applies regardless of whether you have used prophylactic medication or not!
  • The blood tests should be repeated if the result is negative or doubtful and fever persists or recurs.

• For persons having visited a malaria area with low risk and for whom SBET was prescribed:
  • If you have fever: immediately try to get tested for malaria.
  • If this is not possible, and fever persists for longer than 24 hours or recurs: start taking the standby emergency-self-treatment as it was prescribed by your travel health advisor.
  • Even if you have started your self-treatment against malaria: seek medical advice as quickly as possible to get the cause of your fever diagnosed.

• Dengue fever is the world's most common insect-borne infectious disease.
• Great attention should be paid to mosquito protection during the day!
• The disease can cause high fever, muscle and joint pain, and skin rashes. In rare cases, bleeding may occur. There is no specific treatment.
• For personal safety, we strongly recommend that you inform yourself in detail about dengue.

Dengue fever is the most common insect-borne infectious disease worldwide. There are 4 known serotypes of dengue virus, so it is possible to be infected with dengue more than once. Approximately 1 in 4 infected individuals develop symptoms of dengue, resulting in high fever, muscle and joint pain, and skin rash. In rare cases, most often after a second infection, life-threatening bleeding and shock (severe drop of blood pressure) may occur.

In 3 out of 4 cases, an infection with the virus remains asymptomatic. After a short incubation period (5-8 days), 1 out of 4 infected people present an abrupt onset of fever, headache, joint, limb and muscle pain, as well as nausea and vomiting. Eye movement pain is also typical. A rash usually appears on the 3rd or 4th day of illness. After 4 to 7 days, the fever finally subsides but fatigue may persist for several days or weeks.

In rare cases, severe dengue can occur. Particularly susceptible are local children and seniors as well as people who have experienced a prior dengue infection. Tourists extremely rarely present with severe dengue. In the first days, the disease resembles the course of classic dengue fever, but on the 4th/5th day, and usually after the fever has subsided, the condition worsens. Blood pressure drops, and patients complain of shortness of breath, abdominal discomfort, nosebleeds, and mild skin or mucosal hemorrhages. In the most severe cases, life-threatening shock may occur.

There is no specific treatment for dengue virus infection. Treatment is limited to mitigation and monitoring of symptoms: fever reduction, relief of eye, back, muscle and joint pain, and monitoring of blood clotting and blood volume. Patients with severe symptoms must be hospitalised.

For treatment of fever or pain, paracetamol or acetaminophen are recommended (e.g. Acetalgin® Dafalgan®). Drugs containing the active ingredient acetylsalicylic acid (e.g. Aspirin®, Alcacyl®, Aspégic®) must be avoided.

Effective mosquito protection during the day and especially during twilight hours (i.e. sunset) is the best preventive measure:

1. Clothing: Wear well-covering, long-sleeved clothing and long pants and spray clothing with insecticide beforehand (see factsheet “prevention of arthropod bites”)
   
2. Mosquito repellent: Apply a mosquito repellent to uncovered skin several times a day (see factsheet “prevention of arthropod bites”)
   
3. Environmental hygiene: Do not leave containers with standing water (coasters for flower pots, etc.) in your environment to avoid mosquito breeding sites.

Note on dengue vaccines:

two vaccines against dengue are on the market: Qdenga®and Dengvaxia®. The Qdenga® vaccine was approved by the European Union in December 2022. 

However, due to the data available, many European countries, as well as the Swiss Expert Committee for Travel Medicine (ECTM), currently recommend vaccination with Qdenga® only for certain travelers and in special situations. Consultation with a specialist in tropical and travel medicine is therefore recommended.

Of note:

• Qdenga® is not yet licensed in Switzerland and the recommendations for travelers will be limited once Qdenga® is licensed  in Switzerland. 
  
• The vaccine Dengvaxia® is not a vaccine for travelers.
  

Consistent mosquito protection during the day (see above) is still considered the most important preventive measure against dengue!

• Chikungunya is a viral disease transmitted by Aedes mosquitoes.
• Chikungunya can be prevented by protection against mosquito bites.
• It typically presents with severe joint pain of the hands and feet. In a few patients, these may persist for weeks or months.

The infection may present with some or all of the following symptoms: sudden onset of high-grade fever, chills, headache, redness of eyes, muscle and joint pain, and rash. The rash usually occurs after the onset of fever and typically involves the trunk and extremities, but can also include the palms, soles of the feet, and the face.

Often fever occurs in two phases of up to one week duration, with an interval of one to two fever-free days in between. The second phase may present with much more intense muscle and joint pain, which can be severe and debilitating. These symptoms are typically bilateral and symmetric and mainly involve hands and feet, but may also involve the larger joints, such as the knees or shoulders.

About 5-10% of infected people continue to experience severe joint pain even after the fever has subsided, in some cases lasting up to several months or, albeit rare, even years.

• FOPH Switzerland: https://www.bag.admin.ch/bag/de/home/krankheiten/krankheiten-im-ueberblick/chikungunya.html
• WHO - Chikungunya fact sheet: https://www.who.int/news-room/fact-sheets/detail/chikungunya
• Center for Disease Control and Prevention (CDC): https://www.cdc.gov/chikungunya/index.html
  

• Zika is a viral disease transmitted by mosquitoes that bite during the day.
• Zika virus infection during pregnancy (any trimester) can cause fetal malformation.
• In areas at increased risk of transmission (epidemic), specific recommendations must be given to women who are – or wish to become – pregnant.
  

The Zika virus was identified in 1947 in monkeys from the Zika forest in Uganda. Virus circulation has long been limited (a few cases each year) in Africa and South-East Asia. In May 2015, the American continent was affected for the first time, with an epidemic in Brazil that rapidly spread to South America, Central America, and the Caribbean. Since then, the disease has been reported in most tropical and subtropical regions.

The risk of infection is currently low in most regions and does not require specific measures. However, epidemics may occasionally reappear. During epidemics, the risk of transmission is high, and specific recommendations for the traveller are necessary.

In case of fever, it is recommended to consult a doctor. The symptoms of a Zika virus infection may seem similar to those of malaria, for which urgent treatment is necessary, or dengue fever. Treatment for Zika aims for reduction of fever and joint pain (paracetamol). Avoid aspirin and anti-inflammatory drugs (e.g. ibuprofen) as long as dengue fever is not excluded. There is no vaccine available.

In case of pregnancy and fever during or upon return from a Zika virus transmission area, blood and/or urine tests are indicated. In case of confirmed infection, the medical management should be discussed with the gynecologist and infectious/travel medicine specialists.

The risk of infection can be reduced by effective protection from mosquito bites during the day and in the early evening (long clothing, mosquito repellents, mosquito net).

When travelling in an area of increased risk (= declared epidemic) and in order to prevent possible sexual transmission of the virus, it is recommended to use a condom / Femidom during the trip and at least 2 months after return.

Due to the risk of fetal malformation, pregnant women are advised against travelling to areas at increased risk (= declared as epidemic) of Zika transmission at any time during pregnancy (in case of essential travel, a consultation with a travel medicine specialist is advised before departure). Women who wish to become pregnant should wait at least 2 months after their return (or that of their partner) from an area at increased risk of Zika transmission.

• Zika virus infection during pregnancy (any trimester) can cause fetal malformation.
• For most up-to-date information on Zika distribution and / or Zika outbreaks, please consult CDC Zika Travel Information: https://wwwnc.cdc.gov/travel/page/zika-information 

• Geschlechtskrankheiten sind ein weltweit verbreitetes Gesundheitsproblem und können durch Prävention, regelmässiges Testen und Behandlung in den Griff bekommen werden.
• Das Wissen um Risiken sowie Safer-Sex-Praktiken inklusive Kondomgebrauch sind wichtig. Falls Sie mehr dazu erfahren wollen, wie Sie sich während der Reise optimal schützen können, besprechen Sie dies mit einer Fachperson.
• Hatten Sie eine Risikosituation, ist es wichtig mit einer Fachperson so rasch wie möglich Rücksprache zu halten, um zu erörtern, ob eine HIV-Post-Expositions-Prophylaxe (PEP) durchgeführt werden soll, um eine Ansteckung mit HIV zu verhindern.
• Im Nachgang einer Risikosituation ist es wichtig sich auf Geschlechtskrankheiten testen zu lassen. Auch dann, wenn Sie keine Symptome haben.

• Brennen oder Juckreiz im Genitalbereich
  
• Schmerzhaftes oder häufiges Wasserlösen oder auch Schmerzen im Unterleib
  
• Ungewöhnlicher Ausfluss aus dem Penis oder der Vagina
  
• Wunden, Rötungen, Bläschen im Mund/Lippen oder Genitalbereich sowie Warzen im Intimbereich
  
• Manchmal auch Fieber (eher selten)
  

Wichtig: Eine STI kann auch ohne oder mit nur leichten Symptomen auftreten. Auch wenn Sie sich dessen nicht bewusst sind, können Sie andere anstecken. Deshalb ist es wichtig sich testen zu lassen.

• Beachten Sie die Safer Sex Regeln von Love Live. Dazu gehört auch bei jedem Anal- oder Vaginalverkehr Kondome zu verwenden.
  
• Denken Sie daran, dass es bei Oralverkehr auch zu Übertragungen von STIs kommen kann.  
  
• Lassen Sie sich impfen! Es gibt Impfstoffe zum Schutz vor HPV, Hepatitis A und Hepatitis B.
  
• Hatten Sie eine Risikosituation, ist es wichtig mit einer Fachperson so rasch wie möglich Rücksprache zu halten, um zu erörtern, ob eine HIV-Post-Expositions-Prophylaxe (PEP) durchgeführt werden soll, um eine HIV-Infektion zu verhindern. Am wirksamsten ist eine HIV-PEP innerhalb weniger Stunden danach.
  
• Es gibt auch weitere Präventionsmassnahmen für spezielle Situationen (Präexpositionsprophylaxe HIV-PrEP). Sprechen Sie mit einer damit erfahrenen Fachperson vor Abreise darüber.
  
• Denken Sie daran, dass Alkohol oder Drogen zu erhöhtem Risikoverhalten führen.
  
• Denken Sie daran, dass Sie eine weitere Person/bekannter Partner*in bei ungeschütztem Sex anstecken können, sofern bei Ihnen eine unbehandelte STI vorliegt.
  
• Menschen mit einer neu diagnostizierten STI sind angehalten ihre früheren Sexualpartner*innen zu informieren, damit auch sie behandelt werden können.

Durch Bakterien oder Parasiten hervorgerufen
Alle diese Krankheiten können geheilt werden. Wichtig ist dabei, frühzeitig zu testen und umgehend zu therapieren, um Komplikationen und v.a. weitere Übertragungen zu vermeiden.

• Syphilis
  Auch bekannt als Lues. Sie wird durch das Bakterium Treponema pallidum verursacht. Das erste Anzeichen ist eine schmerzlose Wunde an den Genitalien, im Mund, auf der Haut oder im Rektum, die hochgradig ansteckend ist und nach 3 bis 6 Wochen spontan abklingt. Da diese schmerzlos ist, nehmen nicht alle Patienten*innen diese Läsion wahr. Oft heilt diese Infektion jedoch nicht von selbst aus. In der zweiten Phase können Hautausschlag, Halsschmerzen und Muskelschmerzen auftreten. Unbehandelt kann die Krankheit im Verborgenen (latent) bleiben, ohne dass Symptome auftreten. Etwa ein Drittel der Infizierten mit unbehandelter Syphilis entwickelt im Verlauf Komplikationen. Diese Spätform wird als  sogenannt tertiäre Syphilis bezeichnet . In diesem Stadium kann die Krankheit alle Organe befallen: am häufigsten das Gehirn, die Nerven und die Augen. Die Infektion kann während der Schwangerschaft auf den Fötus und bei der Geburt auf das Kind übertragen werden.
  
  
• Chlamydia trachomatis
  Chlamydien können ungewöhnlichen Ausfluss aus dem Penis oder der Vagina, Unbehagen beim Wasserlösen und Unterleibsschmerzen verursachen. Oft treten keine Symptome auf. Unbehandelt können sie zu Unfruchtbarkeit führen und die Krankheit kann auf Sexualpartner*innen übertragen werden. Die Bakterien können auch während der Schwangerschaft auf den Fötus, oder während der Geburt auf das Kind übertragen werden und Augeninfektionen oder Lungenentzündungen verursachen.
  
  
• Gonorrhoe
  Auch bekannt als Tripper. Zu den häufigsten Symptomen gehören Ausfluss aus der Vagina oder dem Penis und schmerzhaftes Wasserlassen. Symptome müssen aber nicht immer auftreten. Sowohl bei Männern als auch bei Frauen kann Gonorrhoe auch den Mund, den Rachen, die Augen und den Anus infizieren und sich auf das Blut und die Gelenke ausbreiten, wo sie in eine schwere Krankheit übergehen kann. Bleibt sie unbehandelt, kann sie eine Beckenentzündung verursachen, die zu chronischen Beckenschmerzen und Unfruchtbarkeit führen kann. Die Krankheit kann während der Schwangerschaft auf den Fötus übertragen werden.
  
  
• Weitere bakterielle STIs: Mykoplasmen und Ureaplasmen. Diese können ebenfalls behandelt werden.
  
  
• Trichomoniasis
  Sie wird durch einen Parasiten verursacht, der mit einer einzigen Dosis eines Antibiotikums behandelt werden kann. Trichomoniasis kann bei Frauen einen übel riechenden Scheidenausfluss, Juckreiz im Genitalbereich und schmerzhaftes Wasserlassen verursachen. Bei Männern treten in der Regel weniger oder keine Symptome auf. Zu den Komplikationen gehört das Risiko einer vorzeitigen Entbindung bei schwangeren Frauen. Um eine Reinfektion zu verhindern, sollten beide Sexualpartner behandelt werden.
  
  

Durch Viren hervorgerufen

• HIV/AIDS - siehe Informationsblatt HIV-AIDS
  
  
• Herpes simplex Virus
  Im Lippen-Mundbereich, auch bekannt als Fieberbläschen, ist nicht heilbar. Herpes kann aber mit Medikamenten bei akuten Beschwerden kontrolliert werden. Die Symptome sind in der Regel schmerzhafte, wässrige Hautbläschen und finden sich an oder um die Genitalien, den Anus oder den Mund. Nach der Erstinfektion ruht das Virus im Körper und die Symptome können über Jahre hinweg wieder auftreten. Schwangere Frauen können die Infektion an ihre Neugeborenen weitergeben, was zu einer bedrohlichen Infektion führen kann.
  
  
• Virale Hepatitis (siehe auch Hepatitis Schweiz)
  
  • Hepatitis A (HAV)
    Hepatitis A ist eine durch Impfung vermeidbare Leberinfektion, die durch das Hepatitis-A-Virus verursacht wird. Das Hepatitis-A-Virus findet sich im Stuhl und im Blut infizierter Personen. Hepatitis A kann durch verunreinigtes Wasser und Lebensmittel sowie bei anal-oralen sexuellen Aktivitäten übertragen werden. Die Patienten*innen leiden an einer akuten und oft schweren Erkrankung, erholen sich aber allermeist spontan.
    
  • Hepatitis B (HBV)
    Das Hepatitis-B-Virus wird durch sexuelle Kontakte sowie durch den Kontakt mit anderen Körperflüssigkeiten, wie z.B. Blut, übertragen. Zur Übertragung kann es z.B. auch bei medizinischen Eingriffen oder Brennen eines Tatoos unter nicht optimalen hygienischen Bedingungen kommen. Hepatitis B kann eine schwere Leberinfektion verursachen, die sowohl zu einer sofortigen Erkrankung, als auch zu einer lebenslang andauernden Infektion führen kann mit möglicher Folge einer dauerhaften Lebervernarbung (Zirrhose) und Krebs. Schwangere Frauen mit Hepatitis B können das Virus während der Geburt auf ihr Kind übertragen. Zu Beginn der Infektion haben Sie möglicherweise keine Symptome.  Das Virus kann auf Sexualpartner*innen übertragen werden. Hepatitis B kann mit antiviralen Medikamenten behandelt werden, ist aber nur selten heilbar. Eine Impfung kann eine Hepatitis-B-Infektion verhindern.
    
  • Hepatitis C (HCV)
    In den meisten Fällen wird Hepatitis C durch den Kontakt mit infiziertem Blut übertragen. Seltener kann es durch analen Sexualkontakt oder von der Mutter auf das Kind während der Schwangerschaft und Geburt übertragen werden. Die meisten Infizierten sind sich ihrer Infektion nicht bewusst, weil sie keine Symptome entwickeln, aber diese chronische Infektion kann zu Leberzirrhose und Krebs führen. Hepatitis C kann behandelt werden, eine Impfung gibt es nicht.
    
    
• Humanes Papillomavirus (HPV)
  HPV ist die häufigste Geschlechtskrankheit. Es gibt eine Vielzahl verschiedener HPV-Typen, und einige von ihnen können Genital-, Anal- und Mundwarzen sowie Gebärmutterhals-, Penis- oder Rachenkrebs verursachen. Die Symptome können auch noch Jahre nach dem Sex mit einer infizierten Person auftreten. Zwei verfügbare Impfstoffe schützen gegen die wichtigsten HPV-Typen, die Gebärmutterhals-, Penis- oder Analkrebs verursachen.
  
  
• Zika - siehe Informationsblatt Zika
  In den meisten Fällen wird es vor allem durch Stechmücken übertragen. Es kann aber auch sexuell übertragen werden. Eine Ansteckung mit Zika während der Schwangerschaft kann bei dem sich entwickelnden Fötus Geburtsfehler wie Mikrozephalie (kleiner Kopf mit neurologischen Ausfällen) verursachen. Die einzige Möglichkeit, eine sexuelle Übertragung des Virus während der Schwangerschaft zu verhindern, besteht darin, Vorsichtsmassnahmen (Kondome) zu treffen oder Sex (mindestens 2 Monate nach der Rückkehr) mit jemandem zu vermeiden, der kürzlich in ein Risikogebiet gereist ist, auch wenn der Reisende keine Symptome hat.

• Love Life: www.lovelife.ch 
  
• Sexuelle Gesundheit Schweiz: www.sexuelle-gesundheit.ch 
  
• Hepatitis Schweiz: https://hepatitis-schweiz.ch/formen/was-ist-hepatitis 
  
• World Health Organization (WHO). Factsheets. Sexually transmitted infections (STIs). 14 June 2019: www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis) 
  
• Centers for Disease Control and Prevention (CDC). Factsheet: Information for Teens and Young Adults: Staying Healthy and Preventing STDs (2017): www.cdc.gov/std/life-stages-populations/stdfact-teens.htm 
  
• Centers for Disease Control and Prevention (CDC). How You Can Prevent Sexually Transmitted Diseases: www.cdc.gov/std/prevention/ 
  
• Centers for Disease Control and Prevention (CDC) Sexual Transmission and Prevention. Zika Virus: www.cdc.gov/zika/prevention/protect-yourself-during-sex.html 
  
• Centers for Disease Control and Prevention (CDC) Zika and Pregnancy; Pregnant Women and Zika (March 2021): www.cdc.gov/pregnancy/zika/protect-yourself.html 

• Schistosomes are parasitic worms that infect humans while bathing or walking in fresh water ponds, lakes, or slow-flowing rivers.
• Avoid bathing, washing, or walking in fresh water in areas endemic for schistosomiasis, also called bilharzia.
• Consult a general practitioner or a specialist in travel and tropical medicine after suspected skin contact with fresh water during a trip.
• Specific diagnostic tests and an effective treatment are available, which can prevent long-term complications.