Mosquito-borne Diseases

1. Mosquito-borne Diseases Central Health Education Unit June 2007

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

3. Common mosquito-borne diseases • Dengue Fever • Japanese Encephalitis • Malaria

4. Dengue Fever

5. Dengue Fever – statistical data Note: Dengue Fever became a notifiable disease since March 1994

6. 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

7. 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

8. Infected mosquito Incubation Period: 3 to 14 daysMost commonly 4 to 7 days Healthy person Dengue Fever – Mode of Transmission Infected person Dengue fever is not spread by contact with infected persons.

9. 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.

10. 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

11. 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

12. 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

13. 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.

14. Japanese Encephalitis

15. Japanese Encephalitis – statistical data Note: Voluntary reporting before 2004, JE became a notifiable disease since 16 July 2004

16. Japanese Encephalitis –Introduction • Etiological agent • Japanese encephalitis virus • Principal vector • Culex tritaeniorhynchus

17. 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.

18. Japanese Encephalitis- Signs and symptoms • Majority are asymptomatic • Low grade fever with headache • More severe infection：quick onset of headache, high feverneck 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.

19. Japanese Encephalitis- Treatment • Seek medical treatment promptly • The mainstay of treatment is supportive

20. 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.

21. 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

22. Malaria

23. Malaria– Statistical data

24. Malaria- Introduction • Etiological agent • A group of malaria parasites • Principle vector • female Anopheline mosquito

25. 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

26. 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.

27. 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.

28. 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

29. Malaria– Vaccination • There are no vaccines against malaria.

30. 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.

31. 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.

32. 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)

33. 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.

34. 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.

35. Prevention of mosquito-borne diseases Personal Protection

36. 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.

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

38. Personal Protection • Install mosquito nets to doors and windows so that mosquitoes can’t get in.

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

40. Personal ProtectionChoosing 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]-aminopropionic acid containing products also have mosquito repellent effects. • Portable ultrasonic devices are less reliable when compared with DEET.

41. 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.

42. 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).

43. 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.

44. Prevention of mosquito-borne diseasesElimination of Mosquitoes The most effective way to eliminate mosquitoes is to： • Keep the environment clean. • Remove stagnant water so that mosquitoes can’t breed.

45. 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.

46. 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.

47. Elimination of Mosquitoes • Cover water containers tightly so that mosquitoes can’t get in to lay eggs.

48. Elimination of Mosquitoes • Dispose of domestic wastes, empty bottles, cans and lunch boxes properly into a covered binto prevent the accumulation of stagnant water.

49. 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.

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