Transcript Indoor Air Quality in Hong Kong

Prevention of
Mosquito-borne Diseases
Central Health Education Unit
June 2007
Mosquito-borne diseases


Common mosquito-borne diseases
Prevention of mosquito-borne
diseases
• Work of the Government
• Personal Protection
• Elimination of Mosquitoes
Common mosquito-borne
diseases
Dengue Fever
 Japanese Encephalitis
 Malaria

Dengue Fever
Dengue Fever – statistical data
Dengue Fever - Statistical data
60
49
50
Imported cases
44
Local cases
40
31 31 31
30
20
10
15
11
10
0
0
20
5
0
0
0
1
0
0
0
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
0
17
Note: Dengue Fever became a notifiable disease since
March 1994
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
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 flight：less
than 100 meter
Most active: 2 hours before
sunset (5-6pm) and
morning (8-9am)
Source of photo:
Food and Environmental Department
Dengue Fever – Mode of Transmission
Infected
mosquito
Healthy person
Infected person
Incubation Period: 3 to 14 days
Most commonly 4 to 7 days
Dengue fever is not spread by contact with
infected persons.
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.
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
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
Treatment (2)


For high fever, wipe the body
with warm water and proper
use of anti-fever drugs can
relieve the fever
Don’t take aspirin-containing
drugs because they worsen the
haemorrhage
Dengue fever patient’s 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.

Japanese
Encephalitis
Japanese Encephalitis –
statistical data
Japanese Encephalitis - statistical data
10
5
5
2
0
0
0
0
0
0
0
0
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
0
Note: Voluntary reporting before 2004, JE became a notifiable disease since 16
July 2004
Japanese Encephalitis –
Introduction

Etiological agent


Japanese encephalitis virus
Principal vector

Culex tritaeniorhynchus
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.
Japanese Encephalitis Signs and symptoms




Majority are asymptomatic
Low grade fever with headache
More severe infection：quick 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.
Japanese Encephalitis Treatment


Seek medical
treatment promptly
The mainstay of
treatment is
supportive
Japanese Encephalitis Vaccination




WHO recommendation：
vaccination 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.
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 No：2150 7235
 www.travelhealth.gov.hk/cindex.html
Malaria
Malaria – Statistical data
Malaria - Statistical data
101
60
54
55
54
47
50
40
30
40
37
35
28
32
20
10
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
0
Malaria - Introduction

Etiological agent


A group of malaria parasites
Principle vector

female Anopheline mosquito
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.

Infected person
Infected
mosquito
Healthy person
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.
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.
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 Enquiries：2150 7235
 Website：www.travelhealth.gov.hk/eindex.html
Malaria – Vaccination

There are no
vaccines
against malaria.
Prevention of
mosquito-borne diseases
Work of the Government

To prevent mosquito-borne diseases
effectively relies on the support and cooperation of both public and private
sectors with the government.
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.
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)
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.
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.
Prevention of
mosquito-borne diseases
Personal Protection
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.
Personal Protection

Avoid going out in the
hours when Aedes
albopicuts feed or wear
light-coloured, longsleeves clothing and
trousers.
Personal Protection

Install mosquito nets
to doors and windows
so that mosquitoes
can’t get in.
Personal Protection
Accommodation should
have air-conditioners or
mosquito nets
 Hang mosquito screens
around your bed
 Use of mosquito coil

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-[NButyl-N-acetyl]-aminopropionic acid
containing products also have
mosquito repellent effects.

Portable ultrasonic devices are less
reliable when compared with DEET.
Safety tips on using
repellents that contain
DEET (1)

Avoid applying high DEET
concentration products (i.e. >35%)

Always read and follow the
instruction label carefully
before using repellents.
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).
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.

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 can’t breed.
Possible Breeding Grounds of
Aedes Albopictus (1)
Artificial containers:
Vases, saucers underneath flower
pots, trays underneath airconditioners, buckets jars and jugs
of earthenware, cement troughs,
dumped tyres and solid wastes such
as cans, disposable cups and bowls,
and plastic bags.
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.
Elimination of Mosquitoes

Cover water containers
tightly so that
mosquitoes can’t get in
to lay eggs.
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.
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.

Elimination of Mosquitoes

Remove or
puncture any
dumped tyres to
prevent the
accumulation of
stagnant water.
Elimination of Mosquitoes
Keep ditches free from blockage.
Elimination of Mosquitoes
Fill up uneven ground surfaces to
prevent the accumulation of stagnant
water.
Elimination of Mosquitoes

Remove stagnant
water immediately if
mosquitoes are found
to be breeding. Use
environmentally
friendly insecticides
such as lavicidal oil if
necessary.
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.
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?
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？
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
Enquiries/Websites
Centre for Health Protection,
Department of Health (www.chp.gov.hk)
 Hong Kong Traveller’s 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

Elimination of mosquito is the most
effective prevention strategy
Let’s remove stagnant
water and eliminate
mosquitoes