Chikungunya fever

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Classification according to ICD-10
A92.0 Chikungunya virus disease
ICD-10 online (WHO version 2019)

The chikungunya is a by Chikungunya virus induced (CHIKV), associated with fever, and joint pain tropical infectious disease transmitted by mosquitoes. The disease is particularly widespread in eastern and southern Africa, on the Indian subcontinent and in Southeast Asia. For some years now, the disease has also been spreading on the islands in the Indian Ocean, in the Caribbean, in Central America near the Caribbean coast and in the north of South America. The word Chikungunya means the crooked walker and originally comes from the Makonde language. In German, the disease is also called "bent man". The exact diagnosis can only be made through blood tests. The disease or the proof of the pathogen is notifiable to different degrees in Germany, Austria or Switzerland. A clinical medical notification is only required in Germany if the disease takes the form of a hemorrhagic fever . Unlike some other tropical viral diseases , this is rarely the case with chikungunya . For most of those affected, the course of the disease is benign and self-limiting; permanent damage and deaths are rare. There is currently no specific treatment option or vaccination. As a preventive measure, the reproduction and spread of certain mosquito species can be combated; travelers to risk areas can only protect themselves by avoiding mosquito bites.

Pathogen

The disease-causing Chikungunya virus is an enveloped single (+) - strand RNA virus ( (+) ssRNA ) and belongs to the genus Alphavirus from the Togaviridae family . In addition, the virus belongs to the group of arboviruses , so it is transmitted through a bite or sting from arthropods . The discovery of the pathogen is dated to the year 1953. The virion has a diameter of about 60 nm and is one of the smaller viruses. It is sensitive to heat (over 58 ° C), dehydration, soap and disinfectants .

According to the different geographical distribution of the virus (see also under Occurrence ), the virus is now divided into five different variants, which differ genetically: a West African, a Central African, an East and South African, one in the Indian Ocean and an Asian.

The possible transmission cycles (human-human = urban cycle or animal-human = sylvatic cycle), as well as the clinical symptoms, are partly similar to dengue fever and yellow fever . The Chikungunya virus is closely related to the O'nyong'nyong virus, which causes the O'nyong-nyong fever . Monkeys and rodents have so far been identified as reservoir hosts .

History and dissemination

geographical distribution until 2006

Chikungunya was first described in 1952 in Tanzania and Uganda . The causative virus was discovered in 1953 and isolated in cell cultures in both countries . The disease later broke out in West Africa as well as in India , Southeast Asia and the Philippines , and was first documented in Asia in 1958 in Thailand . However, the population in these regions has proven to be largely immune to this pathogen. This suggests that the disease was endemic in these areas even before it was first described . In the meantime, the chikungunya fever has spread mainly together with the Asian tiger mosquito ( Stegomyia albopicta ) to large parts of southern Africa and Southeast Asia. Islands in the Pacific and Indian Ocean have also been affected for about ten years . In the last area of ​​occurrence on the islands off East Africa , the residents there and holidaymakers from Europe lack immunity . In addition, there has been a tendency in recent years for the African variants to spread towards Asia.

An increased incidence of chikungunya fever is currently (status: 2015) reported in particular from the following countries or areas: Senegal , Gambia , Guinea , Tanzania , the South and Southeast Asia ( Philippines , Malaysia , Thailand , Cambodia , Myanmar , Sri Lanka , India , Indonesia , Saudi Arabia ) and, since the end of 2013, from some Caribbean islands and from South America.

Outbreaks in Africa, Asia, South America and the Caribbean

In 1999 there was a chikungunya epidemic in the Democratic Republic of the Congo with around 50,000 people affected. The Indonesian island of Java was affected by an epidemic from 2001 to 2003 after the disease had not been epidemic there for 20 years.

From December 2005, a severe chikungunya epidemic raged on the French island of La Réunion . This peaked in February 2006 and slowly subsided by the end of 2006. According to the authorities, 266,000 people and thus around a third of the population were infected, and chikungunya fever was suspected to be the cause of 254 deaths in 2006. Most of the suspected deaths affected older people (over 70 years of age). The epidemic on La Réunion was facilitated by the fact that the virus was previously unknown there and the population previously had no immunity . The economic impact of the epidemic on the tourism-dependent island could be severe.

Other islands in the Indian Ocean were also affected. In 2005, 3,500 people fell ill in Mauritius . There have also been cases in the Comoros island of Mayotte , Madagascar and the Seychelles .

An outbreak in India was remarkably large between February 2006 and May 2007.

Countries and territories in which cases of chikungunya were reported (excluding travel illnesses, as of September 17, 2019, source: CDC )

In 2013, Chikungunya was found on the Caribbean island of St. Martin and thus for the first time in the New World . In early January 2014, in addition to St. Martin, Saint-Barthélemy , Martinique and Guadeloupe were also affected. The Dominican Republic has also been affected since April 2014, and at the end of May there were 38,000 sick people there. In July 2014, Florida saw the first two cases of mainland-borne chikungunya infection.

In November 2014 almost 10,000 officially registered cases in Venezuela were reported by the Minister of Social Affairs, Héctor Rodríguez. At the end of December 2014, at least 75,000 cases were reported in Colombia by the National Health Institute, with Bolivar and Norte de Santander as the worst affected regions.

In January 2015, the Pan American Health Organization reported at least 1.1 million suspected cases across America.

Infections in Europe

In Europe, chikungunya has been diagnosed mainly as an imported disease among returning travelers to the tropics. An exception was a regionally limited outbreak in the Italian province of Ravenna ( Emilia-Romagna region ) in the summer of 2007. By September 4, 2007, a total of 197 cases were reported, most of them in the villages of Castiglione di Cervia and Castiglione di Ravenna. Most of those affected had not previously traveled to a foreign endemic area . Furthermore, the genetic information ( RNA ) of the virus was found in local mosquitoes of the Asian tiger mosquito Stegomyia albopicta . It is therefore considered proven that the virus had spread locally in Italy. The epidemic is believed to have started from a traveler who entered Italy from the Indian subcontinent on June 21, 2007 and who had symptoms of chikungunya fever two days later in Castiglione di Cervia. One death was reported in an 83-year-old man with severe pre-existing conditions.

Another exception is a confirmed case in France in which the disease was transferred from an acutely ill woman returning to the tropics - presumably through contact with her blood - to a nurse. Furthermore, an illness in July 2015; At the time of infection, the sick person was in the Valencian Community (Spain) and in the Languedoc-Roussillon region of southern France . In June 2019, three Icelandic tourists became infected with the virus in the Spanish province of Alicante . However, the Asian tiger mosquito ( Stegomyia albopicta ) has already spread relatively widely in southern Europe, so that theoretically - at least in summer - there is also the possibility of epidemics in Europe. Experts currently estimate the risk of this to be limited, but a precise analysis is not yet possible on the basis of the current data situation. In autumn 2007, eggs of the Asian tiger mosquito were detected for the first time in Germany.

In 2014 the number of cases reported in Germany was 162; previously, 9 to 54 cases of illness had been reported to the Robert Koch Institute every year since 2006 .

In September 2017, the Servizio Regionale di Sorveglianza Malattie Infettive of the Lazio region (Italy) reported a large number of cases of illness occurring in quick succession (Rome and Lazio recorded 102 cases in total, 10 new infections in September 2017). The people affected (5 sick in Lazio, 5 in Rome) had all stayed in the area of ​​the city of Anzio or had relationships with the port city. After the number of infections had risen to 19 in the Italian capital, 71 local areas were declared as risk areas on September 22, 2017 and published in the local press (e.g. the "Pineta Sacchetti" nature reserve), as well as measures to control mosquitoes in these areas . For the Lazio region, the number of reported diseases at this point in time was given as 92.

transmission

The females of the Asian tiger mosquito are among the carriers of Chikungunya fever

According to experts, chikungunya fever can theoretically be transmitted through the bites of various mosquitoes of the genera Anopheles ( malaria mosquitoes ), Stegomyia , Culex and Mansonia . So far, the yellow fever mosquito ( Aedes aegypti , syn. Stegomyia aegypti ) and the Asian tiger mosquito ( Aedes albopictus , syn. Stegomyia albopicta ), which originally came from East Asia , have been identified as clear vectors . This very aggressive mosquito, only about five millimeters in size, black and white striped, which bites during the day and sometimes even through clothing, has spread worldwide and, in addition to chikungunya fever , also transmits dengue fever , yellow fever , western Nile fever and other diseases. This mosquito species is now mostly found in southern Europe in the hot summer months. During the outbreak in Italy in August 2007, the virus was found in this species of mosquito.

Chikungunya fever is not usually passed on directly from person to person, but isolated cases have been reported. In addition, the transmission of sick pregnant women to their unborn children has been proven.

Apparently, a mutated strain of the Chikungunya virus is being transmitted particularly well by the Asian tiger mosquito, so that further spread of the disease in areas where this mosquito has been introduced is to be feared.

Course of the disease and symptoms

After a short incubation period of usually three to seven (maximum range two to twelve) days, those affected usually develop rapidly rising fever with severe joint pain and high sensitivity to touch, so that they can hardly stand upright. The joint problems usually occur in both halves of the body. The fever usually lasts only a few days (three days on average).

Other common symptoms are:

  • Muscle or limb pain (70-99% of cases)
  • Lymph node swelling
  • Rash (about 50% of cases, usually maculopapular - papular normal with scattered islands of skin, not to moderate itching)
  • punctiform skin bleeding ( petechiae )
  • Lighter forms of bleeding from the mucous membranes, for example from the nose or gums (approx. 25% of cases)
  • a headache
  • Exhaustion ("fatigue")
  • Inflammation of the eye (usually recognizable as an injection of the conjunctiva)
  • Gastrointestinal complaints

Usually the disease goes away by itself after about one to two weeks and no damage remains. Asymptomatic courses in which the infected do not notice any symptoms are also possible.

Complications

The symptoms described above can recur occasionally or last up to several months (in rare cases even years). In particular, long-lasting joint problems were described in about 5 to 10% of cases. Furthermore, the disease can occasionally cause fulminant liver inflammation ( hepatitis ), heart inflammation ( pericarditis , myocarditis ), severe neurological disorders, meningitis or even brain damage. In contrast to other viruses that can cause similar tropical diseases, the course of a hemorrhagic fever is very rare in Chikungunya .

In 2006, there were an estimated 266,000 infected people on La Réunion and 248 deaths. The analysis of mortality data in Ahmedabad, India also revealed a worrying finding: during a Chikungunya epidemic that lasted from August to November 2006, almost 3,000 more deaths were recorded than in the corresponding period in the previous four years.

diagnosis

A characteristic clinical sign is severe tenderness on one or both wrists. The routine laboratory tests reveal unspecific changes such as a decrease in the number of lymphocytes ( lymphopenia ), platelet counts ( thrombocytopenia ), red blood cells ( anemia ) and an increase in various enzymes in the serum (especially LDH , ASAT , ALAT and CK ). The C-reactive protein (CRP) is usually only slightly increased. In most cases, IgM antibodies are already present a few days after the onset of the disease, and IgG antibodies are often also present . Various serological methods such as ELISA , immunofluorescence , neutralization and hemagglutination inhibition tests are available for their detection . In the first days of the disease, the virus RNA can also be detected directly in the blood by RT-PCR or virus cultivation in cell culture . The following diagnostic approach is therefore recommended in France: If a patient presents to a medical facility five days after the onset of symptoms or later, a serological test should be performed, followed by RT-PCR.

Differential diagnosis

In particular, the differentiation from dengue fever can cause problems, since the geographical spread of both diseases strongly overlaps and the two diseases cannot be clearly differentiated based on the symptoms. Symptoms similar to chikungunya fever can also be caused by the rarer O'nyong-nyong fever, which is particularly limited to East Africa .

In the course of the disease with long-standing symptoms in the joints of the hand area, the disease can be misinterpreted as rheumatoid arthritis .

therapy

So far there is no effective drug to treat this condition. The virus that caused it has been known for around 50 years, but since this virus and the chikungunya fever it causes have so far only occurred in developing countries, there has been little research into possible drugs.

It is only possible to reduce symptoms, in which non-steroidal anti-inflammatory drugs can be given, especially to combat the sometimes severe joint pain . The administration of acetylsalicylic acid should be avoided at all costs, as this active ingredient irreversibly affects the function of the blood platelets and, as part of the disease, a lack of blood platelets and (rarely) severe bleeding can occur.

prevention

There is currently no approved vaccine for the prevention of this disease. However, French researchers planned to carry out initial tests on rhesus monkeys with an existing vaccine from stocks held by the US Army in 2008 . The United States Army Medical Research Institute of Infectious Diseases had developed a vaccine back in the 1980s and stored tens of millions of units in frozen form. Official approval was no longer sought by the US researchers after the priorities of their work had been changed.

The only effective preventive countermeasures are mosquito control, closed clothing, mosquito repellent and mosquito nets . Fighting mosquitoes in tropical regions is difficult because these insects occur, especially in the rainy season, where chemical control is hardly possible without causing lasting damage to the fauna . In the home, prevention is possible by avoiding standing water. This makes it difficult for the vector mosquitoes to multiply.

Reporting requirement

In Austria, Chikungunya fever is notifiable in the event of illness or death in accordance with Section 1, Paragraph 1, Number 1, Epidemic Act 1950 . Doctors and laboratories, among others, are obliged to report this ( Section 3 Epidemics Act).

In Switzerland, doctors, hospitals, etc., or the examining laboratory are obliged to report positive laboratory analysis results for the disease "Chikunguna fever" / Chikungunya fever or for the pathogen Chikungunya virus . This results from the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Annex 1 or Annex 3 of the Ordinance of the FDHA on the reporting of observations of communicable diseases in humans .

In Germany chikungunya according § 6 Infection Protection Act (IfSG) on suspicion of a virus hemorrhagic fever conditional or according to § 7 IfSG upon detection of the pathogen Chikungunya virus on the part of the physician or lab name reportable . In the second case, it is primarily the heads of the laboratories, etc., and only in the case of hemorrhagic fever also the diagnosing doctor ( Section 8 IfSG) that are required to report .

Individual evidence

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Web links

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This version was added to the list of articles worth reading on November 17, 2006 .