Why did Gorgas succeed?

Transcription

1 Why did Gorgas succeed? (And why have we failed?) Paul Reiter Institut Pasteur

2 My heroes!

3 The European CUC The European cuckoo

4 Cuckoo expert Fellow of the Royal Society (FRS)

5 The Broad Street Pump

6 The Father of Vaccinology Edward Jenner FRS ( )

7 The Father of Epidemiology John Snow ( )

8 The Crazy Cuban

9 The Father of Arbovirology Carlos Finlay ( )

10 Walter Reed ( ) "The case is a beautiful one, as will be seen to-day by the Board of Havana Experts, all of whom, except Finlay, consider the theory a wild one!"

11 Amelia Gorgas ( ) she was, perhaps, the first woman to set the imprint of her personality on the growing University."

12 William Gorgas ( ) Finlay s reasoning for selecting the Stegomyia as the bearer of yellow fever is the best piece of logical reasoning that can be found in medicine anywhere."

13 Sir William Gorgas ( ) Finlay s reasoning for selecting the Stegomyia as the bearer of yellow fever is the best piece of logical reasoning that can be found in medicine anywhere."

14 Fred Soper ( ) His epic achievements arose from his fanaticism, his absolutism, his commitment...

15 A success! Reiter, P. (2013). Surveillance and Control of Urban Dengue Vectors. In Dengue and Dengue Haemorrhagic Fever. Ed. Gubler, DJ. CAB Pres, Wallingford

16 Reiter, P. (2013). Surveillance and Control of Urban Dengue Vectors. In Dengue and Dengue Haemorrhagic Fever. Ed. Gubler, DJ. CAB, Wallingford

17 A temporary setback? Reiter, P. (2013). Surveillance and Control of Urban Dengue Vectors. In Dengue and Dengue Haemorrhagic Fever. Ed. Gubler, DJ. CAB, Wallingford

18 But things got worse Reiter, P. (2013). Surveillance and Control of Urban Dengue Vectors. In Dengue and Dengue Haemorrhagic Fever. Ed. Gubler, DJ. CAB, Wallingford

19 Improvement? Reiter, P. (2013). Surveillance and Control of Urban Dengue Vectors. In Dengue and Dengue Haemorrhagic Fever. Ed. Gubler, DJ. CAB, Wallingford

20 Latest data, 2013

21

22 Where is it???

23 Singapore!!! 710 km² (Havana is km²) $60 MILLION US per year More dengue than ever

24 There is NOWHERE on this earth where dengue is under control!

25 Poem: Ode to Ae. aegypti control Those golden days... The perfect way.. Let us-(s)pray... The mess today! (Anon, 21st Century)

26 Gorgas in Havana. Success!!! Water storage vessels Wash basins Horse troughs Gutters Natural sites

27 Try to imagine! Few motor vehicles No airplanes Cities: small scale No plastics Few disposable containers Few tires Yellow Jack: a terrifying disease Authoritarian authorities...

28 Gorgas in Panama One pound of pyrethrum per house (adulticide) First application Second application. Third application Roosevelt intervenes... Return to source reduction...

29 Summary: the golden days Source reduction was a great success, but. Conditions were different Target disease was different Organization of operations was different Public attitudes were different

30 Era II: The perfect way

31 Focal treatment... Find infested containers Spray infested containers Spray 50 cm around infested containers Eradication in 22 countries

32 Oviposition behavior Observations of ovipositing females Number of eggs per trap per night RAPD-PCR Eggs marked with rubidium Dissection of gravid mosquitoes

33 Skip oviposition Ae. aegypti: not all eggs in one basket Females visit many sites

34 Longevity of the mosquito Days from eclosion to completion of first egg batch Daily survival probability = n parous rate n is generally assumed to be 3 to 4 days

35 But n can be as high as 10 days! 70 percent surviving 10 days gonotrophic cycle (days)

36 Era III: let us spray! Thermal fog Cold fog (ULV) Hand foggers Road vehicles Aircraft

37 The residual impact of DDT? The campaign eliminated malariologists, not malaria Fenner et al., 1998 The science of malaria, which had developed slowly and painfully from the beginning of the century was almost overnight converted to the rather simplistic technology of malaria eradication Jeffery, 1976

38 Ultra Low Volume (ULV) Advantages: no diluent no mixing machinery less hazard on the road less liquid cargo smaller/simpler machines faster application rate lower overall costs

39 Ultra Low Volume (ULV) Other advantages loud noise flashing light nasty smell government logo press announcements

40 Bio-assays Nearly 100% kill but less than 25% in resting sites...

41 Ovitraps with hay infusion

42 Twelve trials of ULV (malathion and resmethrin)

43 Backpack aspirator

44 Oviposition vs. adult collections eggs per site day Adults: Eggs: adults per room

45 Field trial: oviposition rate eggs per site day Treated: Untreated:

46 Field trial: adult females 2 mosquitos per room Treated: Untreated: day

47 Poor males!!! 4 mosquitos per room day Treated: Untreated:

48 Treated site Treatment 25 Nombre de femelles Pare Nullipare Gravide 5 0 J1 J2 J3 J4 J5 J1+ J2+ J3+ J4+ J5+ Jours de capture avant et après traitement

49 ULV Treatment

50 Airflow around buildings

51 Penetration vs. droplet sizes 6 frequency logits indoor patio front droplet size (µ) 100

52 Era IV: The mess today! Many countries try a little, and fail Some countries try hard, but also fail Other countries don t try

53 The reality today Enormous cities Dense populations Massive infestation indices Difficult access Declining resources Insecticide resistance

54 Four serotypes Demography Population mobility Lack of funds Other factors

55 We still need better knowledge: Infested containers vs. numbers of adults? Duration of the gonotrophic cycle? Survival rate of adults? Factors that affect adult survival? Dispersal distances of adults? Factors affecting dispersal of adults?

56 So we don t know our target! How many containers? How many mosquitoes? Economics of control? Sustainability?

57 Transmission model 50% less mosquitoes 90% less mosquitoes 1.2% less cases 2.0% less cases

58 [Herd immunity] [Vector density] [Cases]

59 The secret of Gorgas success?

60 Conclusion Herd immunity is key to successful dengue control Vaccination + vector control may win the game We need new vector control methods

61 Restoration and innovation Focal treatments Wolbachia Auto-dissemination RIDL

62 Sterile Insect Technique (SIT) by irradiation Entire insect is treated Fitness greatly reduced Fruit-fly factory, Guatemala

63 SIT by Genetic Technology Release of insects with a dominant lethal gene (RIDL )

64 RIDL Tetracycline blocker promoter tta effector life

65 RIDL promoter tta Lethal gene effector death

66 Thank you!