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About mosquito-borne infectious diseases

Dengue fever, Zika virus infection, etc.

Last Updated December 19, 2023

Contents

What is mosquito-borne infections?

Mosquito-borne infectious diseases refer to general infectious diseases in which mosquitoes carrying pathogens such as viruses and protozoes are transmitted by sucking human blood. Typical examples include West Nile fever, yellow fever, Zika virus infection (Zika fever), Chikungunya fever, dengue fever, Japanese Encephalitis and malaria.

Be careful when traveling abroad!

Overseas, many mosquito-borne infectious diseases have been reported.
When traveling abroad, check the local epidemic situation before traveling, and take measures to prevent infection and take measures as necessary.
In addition, many of these infectious diseases have been found to be able to transmit mosquitoes (Aedes albopictus, etc.) that inhabit widely in Japan.
Care must be taken even after returning to Japan to prevent the spread of infection from those who have been infected overseas and returned to the country.

To prevent infection

For measures to prevent infection, please refer to the bottom of the page to prevent infection.

Do not increase the number of mosquitoes or prevent mosquito bites
Poster for mosquito-borne infections

Response of Yokohama City

  • "Yokohama-shi mosquito-borne infectious disease measures guideline" (PDF: 338KB)(April 2016)
    It was formulated based on the Ministry of Health, Labour and Welfare's "Guidelines for Prevention of Specific Infectious Diseases Concerning Mosquito-borne Infectious Diseases" and "Guidelines for Countermeasures and Countermeasures for Mosquito-borne Infectious Diseases such as Dengue and Chikungunya Heat (for Local Governments)".
  • "Monitoring survey of mosquitoes in Yokohama City"
    In Yokohama City, we conduct mosquito monitoring surveys in parks and harbor areas in the city. The website provides an overview of mosquito habitat surveys and virus test results.

Major mosquito-borne infections

Zika virus infection (Zika fever)

Characteristics of Zika virus infection
CauseZika virus (Fravivirus family Flavivirus)
Route of infectionIt is transmitted by being bitten by mosquitoes (albopictus such as Aedes aegypti and Aedes albopictus) that carry Zika virus. It can also be transmitted by blood donation or sexual intercourse.
Area of occurrenceAsia, Central and South America and the Caribbean, Africa, Oceania and Pacific Islands, North America
SymptomsAfter an incubation period of 2 to 12 days (often 2 to 7 days), mild fever, headache, joint pain, muscle pain, rash, conjunctivitis, etc. appear. Infection in pregnant women has also been shown to cause fetal microcephaly and neurological symptoms (Gilan-Barre syndrome).
TreatmentThere is no special treatment and coping therapy is given.
PreventionThere is no vaccine. Preventing mosquito bites is the only way to prevent it.

What should be noted

  1. Those who are traveling to endemic areas
    Check the epidemic status on the Ministry of Health, Labour and Welfare's Quarantine Station website (outside site), and take sufficient measures to prevent mosquito bites locally. (For countermeasures, please refer to (bottom page) to prevent infection.)
  2. Those who are pregnant or their partners
    Infections during pregnancy can cause fetal microcephaly. If you are pregnant or pregnant, refrain from traveling to endemic areas as much as possible.
    If you must travel, take strict mosquito control measures locally.

Prevention of sexually transmitted diseases

  • For both men and women, during stay in the endemic area and for six months after returning from the endemic area (or during pregnancy if the partner is a pregnant woman), use condoms or refrain from sexual activity during sexual activity, regardless of symptoms Please do.
  • Women who have traveled to endemic areas and wish to have children should refrain from pregnancy for at least six months, regardless of symptoms.
Enlightenment flyer (created by Yokohama City Public Health Center)

To Medical Institutions (Yokohama City Public Health Center)

Related Sites

Dengue fever

Characteristics of dengue fever
CauseDengue virus (Fravivirus family Flavivirus)
Route of infectionIt is transmitted by being bitten by a mosquito carrying the dengue virus (such as Aedes aegypti and Aedes aegypti).
Area of occurrenceIt is prevalent in tropical and subtropical regions such as Asia, Central and South America, and Africa.
Every year, it is reported that there are 50 to 100 million affected people worldwide.
SymptomsAfter an incubation period of 2 to 15 days (often 3 to 7 days), sudden fever, headache, joint pain, muscle pain, rash, etc. appear. Some may have severe dengue hemorrhagic fever.
Prevention and treatmentThere is no vaccine. In addition, there is no special treatment, coping therapy is given.
  • In recent years, the number of reports of people infected overseas and develop symptoms after returning to Japan has increased. In 2014, domestic infection was confirmed for the first time in about 70 years.
  • About 10 to 20 patients are reported every year in Yokohama City, and caution is required.
  • What are the countermeasures?To prevent infection (at the bottom of the page)Please check it out.

To Medical Institutions (Yokohama City Public Health Center)

Related Sites

Chikungunya heat

Characteristics of chikungunya heat
CauseChikungunya virus (Arpha virus genus, Toga virus)
Route of infectionIt is transmitted by being bitten by a mosquito carrying the Chikungunya virus (such as Aedes aegypti and Aedes albopictus).
Area of occurrenceOccurred in Africa, South Asia, and Southeast Asia. The epidemic was also reported in Italy in 2007.
SymptomsAfter an incubation period of 3 to 12 days (usually 3 to 7 days), sudden fever, joint pain, headache, muscle pain, rash, etc. appear.
Prevention and treatmentThere is no vaccine. In addition, there is no special treatment and coping therapy is given.

Related Sites

West Nile fever

Characteristics of West Nile Heat
CauseWest Nile virus (Fravivirus family Flavivirus)
Route of infectionIn nature, infections are repeated between birds (mainly crows) and mosquitoes, and humans are transmitted by being bitten by mosquitoes carrying the West Nile virus (such as squid and yabuka such as Aedes albopictus) .
Area of occurrenceIt occurs in a wide range of Africa, Western Europe, the Middle East, Central Asia, and West Asia, and the epidemic has also occurred in the western hemisphere such as Western Europe and the United States, which had not been reported until recently.
SymptomsAfter an incubation period of 2 to 14 days, sudden fever, headache, back pain, muscle pain, rash, etc. appear. In severe cases, meningitis and encephalitis may develop.
Prevention and treatmentThere is no vaccine. In addition, there is no special treatment and coping therapy is given.

Related Sites

Malaria

Characteristics of Malaria
CauseMalaria beetle
  • Plasmodium vivax, a protozoa genus Plasmodium vivax
  • Plasmodium falciparum (tropical thermal malaria parasite)
  • Plasmodium malariae (four-day thermal malariae)
  • Single or mixed infections such as Plasmodium ovale (ovarian malaria protozoa), etc.
Route of infectionIt is transmitted by being bitten by a mosquito (Handaraka) that carries malaria protos.
Area of occurrence

It occurs in tropical and subtropical regions such as Africa, Asia, South Pacific countries, and Central and South America.
According to estimates by the World Health Organization (WHO), there are 200 million affected people and more than 2 million deaths annually, and there are several reports of people infected overseas in Yokohama every year.

SymptomsAfter an incubation period of 10 to 30 days, fever, face red tide, headache, muscle pain, respiratory symptoms, gastrointestinal inflammation, etc. appear. In addition, fever repeats the fever period and the non-heat period. (The interval between incubation period, symptoms, and fever varies depending on the type of malaria parasite.)
If not treated promptly, it can become severe and lead to death.
Prevention and treatmentPreventive oral antimalaria drugs is effective. Also, if you are diagnosed with malaria, you will be treated with antimalaria drugs.

Related Sites

Yellow fever

Characteristics of yellow fever
CauseYellow fever virus (Fravivirus family Flavivirus)
Route of infectionIt is transmitted by being bitten by a mosquito carrying the yellow fever virus (mainly Aedes aegypti).
Infection cycle
  1. Rainforest (forest type) cycle
    Primates other than humans - mosquitoes - primates other than humans (infects humans accidentally)
  2. Urban cycle
    Human-mosquito-human (possibly large outbreaks)
  3. Intermediate (savanna) cycle
    Human-mosquito-human primates
Area of occurrenceIt is prevalent in the tropical regions of Africa and Central and South America.
According to estimates by the World Health Organization (WHO), there are 80,000 to 170,000 affected people and 60,000 deaths annually.
SymptomsAfter an incubation period of 3 to 6 days, fever, headache, muscle pain, back pain, vomiting, etc. appear. In many cases, infection ends with no symptoms or mild symptoms, but about 15% of the affected people become more severe. In that case, relapse of high fever and jaundice and bleeding tend to progress, following the period of remission from several hours to one day (not completely cured but temporarily relieve or disappearing symptoms), and 20 to 50% are said to die.
Prevention and treatmentVaccinations is effective (inoculation is carried out only at specific vaccination institutions). Depending on the country, you may be required to show a yellow fever vaccination certificate when entering Japan. Also, treatment is mainly coping therapy.

Related Sites

To prevent infection

Those who are traveling abroad

  • Be careful not to get bitten by mosquitoes!
  • What is the status of infectious disease epidemics at destinations?Quarantine Station, Ministry of Health, Labour and Welfare FORTH "Overseas Infectious Disease Information" page (external site)YeahMinistry of Foreign Affairs “Overseas Safety Website” (outside site)Let's check it one by one.
  • At your destination, wear long sleeves and long pants, avoid sandals with bare feet, and be careful not to expose bare skin as much as possible.
  • Use insect repellents (repellents) appropriately.
    • Points of use
    • Choose one that contains effective ingredients to prevent mosquitoes, "Deat (DEET)" and "Ikari Jin (Pikalidin)". (In Japan, Deet is sold at a concentration of up to 30%, Ikari Gin is sold at a concentration of up to 15%.)
    • Follow the usage, dosage, and precautions according to your age, and use them appropriately.
    • Water and sweat reduce the sustainability of the effect, so repain it frequently.
    • If you use a sunscreen, apply an insect repellent over it.
    • Don't forget small exposed areas such as necks, ears, backs of hands, and ankles.
  • Use mosquito coils and mosquito nets indoors to prevent mosquito bites (Aedi aegypti is also active indoors).
  • If you have symptoms such as fever when returning to Japan or after returning to Japan, you will be able to use the quarantine station or the quarantine station.To the nearest ward, Health and Welfare Center Health Promotion SectionPlease contact us.
  • If you have symptoms such as fever, do not drink commercially available antipyretic analgesics.
  • After returning to Japan, take measures to prevent mosquito bites for about two weeks without symptoms.
  • Please refrain from donating blood within 4 weeks from the date of return to Japan to prevent the spread of infection by transfusion.
  • What are the measures against infectious diseases when traveling abroad?Another page (Yokohama City Public Health Center)Please refer to it.

Let's reduce the number of mosquitoes around us

To Medical Institutions

If a patient suspected of dengue fever or Zika virus infection is consulted.

If you are suspected of being infected, please refer to the “Medical Guidelines for Mosquito-borne Infectious Diseases (outside site)” prepared by the National Institute of Infectionery and respond as follows.

Beware of antipyretics to prescribe!

When treating patients suspected of having dengue fever, be careful with antipyretics to prescribe.

  • The prescription is acetaminophen, etc., and it is specified that the following should not be used. (National Institute of Infectious Diseases)Medical treatment guidelines for mosquito-borne infectious diseases (outside site)See ".
    • Aspirin and other salicylic acid-based antipyretics: To promote bleeding tendency and acidosis.
    • Nonsteroidal anti-inflammatory drugs such as ibuprofen: To promote gastritis or bleeding.

Press release materials

2017

June 1, 2017 "We call on mosquito measures by bus and subway-do not increase mosquitoes this summer! Don't get stuck by mosquitoes! ～」（PDF：405KB）

2016

May 18, 2016 "We strengthen prevention enlightenment of mosquito-borne infectious disease" (PDF: 733KB)

2015

June 2, 2015 "we start monitoring investigation of mosquito in 25 places in the city!" （PDF：348KB）

Related Sites

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Inquiries to this page

Health and Safety Division, Medical Care Bureau Health and Safety Department

Telephone: 045-671-2463

Telephone: 045-671-2463

Fax: 045-664-7296

Email address: ir-kenkoanzen@city.yokohama.jp

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