Prevention of Mosquitoborne Diseases

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Prevention of Mosquito-borne Diseases
Central Health Education Unit June 2007
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Mosquito-borne diseases

• Common mosquito-borne diseases
• Prevention of mosquito-borne diseases
• Work of the Government
• Personal Protection
• Elimination of Mosquitoes

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Common mosquito-borne diseases

• Dengue Fever
• Japanese Encephalitis
• Malaria

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Dengue Fever
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Dengue Fever statistical data
Note Dengue Fever became a notifiable disease
since March 1994
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Dengue Fever - Introduction

• Etiological agent
• Dengue viruses (DEN-1, DEN-2, DEN-3 and DEN-4) -
  flaviviruses
• Principal vector
• Aedes albopictus
• Aedes aegypti

Source of photo Food and Environmental
Department
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Dengue Fever Habitual Behaviour of Aedes
Albopictus

• Usually breed in stagnant water
• Usually active in dark or shaded places outdoors,
  but indoor activity is also possible
• Distance of flightless than 100 meter
• Most active 2 hours before sunset (5-6pm) and
  morning (8-9am)

Source of photo Food and Environmental
Department
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Dengue Fever Mode of Transmission
Infected person
Dengue fever is not spread by contact with
infected persons.
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Dengue Fever - Symptoms

• Fever continuous for 3 to 7 days
• Severe headache
• Joint pain, muscle pain, pain behind eyeballs
• Nausea, vomiting, and rash
• In very rare cases, the condition may worsen into
  dengue haemorrhagic fever, leading to internal
  bleeding, shock, or even death.

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Dengue Fever - Treatment

• At present, no specific drug that can treat
  dengue fever effectively.
• Patient should be isolated in a mosquito-free
  environment to prevent the spread of disease

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Treatment (1)

• Patients infected with classical dengue usually
  recovers in 1 to 2 weeks
• For serious cases, supportive treatments are
  provided by hospitals
• If you suspect that you have dengue fever, you
  should seek medical treatment promptly

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Treatment (2)

• For high fever, wipe the body with warm water and
  proper use of anti-fever drugs can relieve the
  fever
• Dont take aspirin-containing drugs because they
  worsen the haemorrhage

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Dengue fever patients immunity

• Immunity is gained against that serotype
  after recovery from its infection. However, no
  effective protection is conferred against
  infection by the other three serotypes.
• If the patient is infected with the other three
  different serotypes, it will increase the risk of
  getting haemorrhagic fever.

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Japanese Encephalitis
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Japanese Encephalitis statistical data
Note Voluntary reporting before 2004, JE became
a notifiable disease since 16 July 2004
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Japanese Encephalitis Introduction

• Etiological agent
• Japanese encephalitis virus
• Principal vector
• Culex tritaeniorhynchus

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Japanese Encephalitis Mode of Transmission

• Spread by Culex tritaeniorhynchus
• The mosquitoes infected by feeding on pigs and
  wild birds infected with the Japanese
  encephalitis virus

within 4-14 days

• The disease is not directly transmitted from
  person to person or from animal to human.

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Japanese Encephalitis - Signs and symptoms

• Majority are asymptomatic
• Low grade fever with headache
• More severe infectionquick onset of headache,
  high fever neck stiffness, impaired mental state,
  coma, tremors, occasional convulsions and
  paralysis.
• Death rates may range from 5 to 35. Patients
  who survive may have neurological consequences.

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Japanese Encephalitis - Treatment

• Seek medical treatment promptly
• The mainstay of treatment is supportive

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Japanese Encephalitis - Vaccination

• WHO recommendationvaccination for the whole
  country is indicated when there are 10 to 100
  cases for every 100,000 population.
• Provide 80-100 immunity, but may have adverse
  reactions.
• Immunity may last for about 3 years.
• Should consult medical officer for vaccination.

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Japanese Encephalitis Do I need to have
vaccination?

• WHO recommendation
• Travellers going to endemic areas particularly in
  rural areas and
• staying over 30 days are
• recommended for vaccination.
• Where can I get the vaccination?
• Travel Health Centres of the Port Health Office
  of the Department of Health
• Enquiry No2150 7235
• www.travelhealth.gov.hk/cindex.html

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Malaria
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Malaria Statistical data
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Malaria - Introduction

• Etiological agent
• A group of malaria parasites
• Principle vector
• female Anopheline mosquito

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Malaria Mode of Transmission

• When the mosquito bites a malaria patient, the
  mosquito
• becomes infected and will pass on the disease
  when it
• bites another person.
• Malaria is not transmitted from person to person.
• Malaria can be transmitted through contaminated
  blood
• transfusion, organ transplant, or shared
  needles or
• syringes.
• It may also be transmitted from a mother to her
  
• foetus/newborn baby before or during delivery.

7-30 days later
Infected mosquito
Healthy person
Infected person
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Malaria Signs and symptoms

• Intermittent fever, chills, sweating, headache,
  tiredness, poor appetite and muscle pain.
• In typical cases, the fever comes, then subsides
  for 1 to 3 days and then comes again in a
  cyclical pattern.
• Complications include anaemia, liver and kidney
  failure, seizures, mental confusion, coma, and
  death if the disease is not treated promptly.

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Malaria Treatment

• Consult a doctor for early diagnosis is crucial.
• The doctor would prescribe a course of
  anti-malarial drugs with other supportive
  measures.
• The patient should complete the whole course of
  medication to ensure clearance of the malaria
  parasites.

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Malaria Prevention

• Recommendation from WHO
• If you travel to areas where malaria is
• common, you should start taking the
• anti-malarial drugs two to three weeks
• before the trip, continue for four more
• weeks after leaving the malarious area.
• From where I can obtain the anti-malarial drugs?
• Travel Health Centre, Department of Health
• For Enquiries2150 7235
• Websitewww.travelhealth.gov.hk/eindex.html

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Malaria Vaccination

• There are no vaccines against malaria.

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Prevention of mosquito-borne diseases

• Work of the Government
• To prevent mosquito-borne diseases effectively
  relies on the support and co-operation of both
  public and private sectors with the government.

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Work of the Government

• Publicity and Health Education
• Provide health education on personal protection
  against mosquito-borne diseases for general
  public.
• Publicize personal protection against
  mosquito-borne diseases for travellers.
• Latest updates on dengue fever for healthcare
  workers through periodicals, mails and internet.

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Disease surveillance

• Dengue fever, Japanese encephalitis and Malaria
  have been brought into one of the statutory
  notifiable diseases.
• web-based Central Notification Office (CENO
  On-line)

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Disease surveillance

• Contact tracing, epidemiological investigations
  on disease outbreaks.
• Liaise with relevant department, e.g. Food and
  Environmental Department for following up control
  measures.
• Collaborate with other departments and Hospital
  Authority in formulating response measures to
  prevent local spread of Dengue fever.

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Disease surveillance

• Maintain close liaison with nearby regions and
  oversea countries.
• Make announcement to general public on reported
  cases and disease situation of nearby regions and
  remind public of preventive measures.

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Prevention of mosquito-borne diseases

• Personal Protection

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Personal Protection

• The best protection is to avoid being
• bitten by mosquitoes by paying
• attention to the following
• Avoid staying in dark, outdoor
• places such as brushwood, pavilions,
• or the shade of a tree during the
• hours when Aedes albopictus is
• active.

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Personal Protection

• Avoid going out in the hours when Aedes
  albopicuts feed or wear light-coloured,
  long-sleeves clothing and trousers.

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Personal Protection

• Install mosquito nets to doors and windows so
  that mosquitoes cant get in.

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Personal Protection

• Accommodation should have air-conditioners or
  mosquito nets
• Hang mosquito screens around your bed
• Use of mosquito coil

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Personal Protection Choosing the insect
repellents

• DEET containing products, such as repellents,
  anti-mosquito patches and spray are generally
  most effective to avoid mosquito bites.
• Citronella, Soybean oil and 3-N-Butyl-N-acetyl-a
  minopropionic acid containing products also have
  mosquito repellent effects.
• Portable ultrasonic devices are less reliable
  when compared with DEET.

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Safety tips on using repellents that contain DEET
(1)

• Avoid applying high DEET
• concentration products (i.e. gt35)
• Always read and follow the
• instruction label carefully
• before using repellents.

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Safety tips on using repellents that contain
DEET (2)

• As rare reports about application of repellents
  with DEET associated with seizures in young
  children, therefore the low concentration product
  (10 DEET) should be used on children.
• DEET is not recommended for use on infants less
  than 2 months of age. They should use mosquito
  net for health protection (e.g. infant carrier
  draped with elastic edge mosquito net).

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Safety tips on using repellents that contain DEET
(3)

• Never use repellents over wounds or irritated
  skin.
• Apply the repellent on exposed skin surfaces
  only
• or on top of clothing. Do not use under
  clothing.
• Do not attach the anti-mosquito patches
  directly
• on the skin if it is specifically for clothing.
• Wash repellent-treated skin with soap and water
• when you come indoors.
• When using sprays, do not spray directly on face
  
• spray on hands first and then apply to face. Do
  
• not apply to eyes or mouth.

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Prevention of mosquito-borne diseases
Elimination of Mosquitoes

• The most effective way to eliminate mosquitoes
  is to
• Keep the environment clean.
• Remove stagnant water so that mosquitoes cant
  breed.

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Possible Breeding Grounds of Aedes Albopictus (1)
Artificial containers Vases, saucers
underneath flower pots, trays underneath
air-conditioners, buckets jars and jugs of
earthenware, cement troughs, dumped tyres and
solid wastes such as cans, disposable cups and
bowls, and plastic bags.
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Possible Breeding Grounds of Aedes Albopictus (2)
Natural containers The hollow space inside a
bamboo, hollows of a tree and the rachis of a
leaf.
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Elimination of Mosquitoes

• Cover water containers
• tightly so that
• mosquitoes cant get in
• to lay eggs.

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Elimination of Mosquitoes

• Dispose of domestic wastes, empty bottles, cans
  and lunch boxes properly into a covered bin to
  prevent the accumulation of stagnant water.

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Elimination of Mosquitoes

• Change water for vases
• and aquatic plants at
• least once a week,
• leaving no water under
• the pots or in the
• bottom saucers.
• Scrub the container
• surfaces thoroughly to
• prevent mosquito eggs
• sticking on them.

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Elimination of Mosquitoes

• Remove or puncture any dumped tyres to prevent
  the accumulation of stagnant water.

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Elimination of Mosquitoes
Keep ditches free from blockage.
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Elimination of Mosquitoes
Fill up uneven ground surfaces to prevent the
accumulation of stagnant water.
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Elimination of Mosquitoes

• Remove stagnant water immediately if mosquitoes
  are found to be breeding. Use environmentally
  friendly insecticides such as lavicidal oil if
  necessary.

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Elimination of Mosquitoes

• In cultivation ponds, water tanks or large
  containers, biological controls such as keeping
  fishes to eat mosquito larvae would be a good
  option.

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Mosquito Elimination Checklist (1)

• Are containers and other items where water could
  accumulate disposed of properly? (For example,
  throwing empty cans, foam rubber boxes, cups and
  bottles into a covered bin)
• Are water containers covered properly?

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Mosquito Elimination Checklist (2)

• Are ditches free from blockage?
• Are containers with stagnant water cleaned
  regularly?(For example, vases, saucers underneath
  flower pots, water storage device of an
  air-conditioner, water tanks and pools)
• Are uneven ground surfaces filled to prevent the
  accumulation of stagnant water?

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Seek medical consultation immediately

• Having been bitten by a
• mosquito and displaying
• symptoms afterwards
• Falling ill, especially having
• a fever within one month
• after you have returned
• from abroad

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Enquiries/Websites

• Centre for Health Protection,
• Department of Health (www.chp.gov.hk)
• Hong Kong Travellers Health Service, Department
  of Health (www.travelhealth.gov.hk/eindex.html)
• 24-Hour Health Education Hotline, Department of
  Health (2833 0111)
• Food and Environmental Hygiene Department Hotline
  2868 0000
• Website www.fehd.gov.hk

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Elimination of mosquito is the most effective
prevention strategy
Lets remove stagnant water and eliminate
mosquitoes
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Thank You!