Embed Size (px)
Citation preview
Mosquito-borne DiseasesMosquito-borne Diseases
Central Health Education UnitCentral Health Education Unit
June 2007June 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 Common mosquito-borne diseasesdiseases
Dengue Fever Japanese Encephalitis Malaria
Dengue FeverDengue Fever
Dengue Fever – statistical data
10
0
15
050
11
0
17
0
44
20
49
1
31
0
31
0
31
00
10
20
30
40
50
60
1997199819992000200120022003200420052006
Dengue Fever - Stati sti cal data
Imported casesLocal cases
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 Dengue Fever – Habitual Behaviour of Behaviour of Aedes AlbopictusAedes 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 TransmissionDengue Fever – Mode of Transmission
Infected mosquito
Healthy person Infected person
Dengue fever is not spread by contact with infected persons.
Incubation Period: 3 to 14 daysMost commonly 4 to 7 days
Dengue Fever - SymptomsDengue 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 - TreatmentDengue 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)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
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
Treatment (2)Treatment (2)
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.
Dengue fever patient’s immunity
JJapanese apanese EncephalitisEncephalitis
Japanese Encephalitis – statistical data
Note: Voluntary reporting before 2004, JE became a notifiable disease since 16 July 2004
0 0 0 0 0 0 0
5
2
00
5
10
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Japanese Encephalitis - statistical data
Japanese Encephalitis –Introduction Etiological agent
Japanese encephalitis virus
Principal vector Culex tritaeniorhynchus
Japanese Encephalitis – Mode Mode of Transmissionof Transmission
The disease is not directly transmitted from person to person or from animal to human.
Spread by Culex tritaeniorhynchus The mosquitoes infected by feeding on pigs and wild
birds infected with the Japanese encephalitis virus
within 4-14 days
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
MalariaMalaria
10154 55
35
4754
28
3732
40
0
10
20
30
40
50
60
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Malaria - Statistical data
MalariaMalaria – Statistical data– Statistical data
Malaria - Introduction Etiological agent
A group of malaria parasites
Principle vector female Anopheline mosquito
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 mosquitoInfected person
Healthy person
7-30 days later
MalariaMalaria – Mode of Transmission– Mode of Transmission
Malaria – Signs and symptoms– 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.
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 – Treatment– Treatment
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 – Prevention– Prevention
Malaria – Vaccination– 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 co-operation of both public and private sectors with 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.
Work of the Government
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)
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
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 ProtectionPersonal 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, long-sleeves 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
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]-aminopropionic acid containing products also have mosquito repellent effects.
Portable ultrasonic devices are less reliable when compared with DEET.
Personal Protection Choosing the insect repellents
Safety tips on using Safety tips on using repellents that contain repellents that contain
DEET (1)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 Safety tips on using repellents that contain DEET (2)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).
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.
Safety tips on using repellents Safety tips on using repellents that contain DEET (3)that contain DEET (3)
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 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.
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/WebsitesEnquiries/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
