Climate and Health Early Warning

8/9/2019 Climate and Health Early Warning

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David GikunguKenya Meteorological Department



As geographical and temporal range s expand withglobal warming, it i s expected that the prevalenceof climate sen sitive disea ses may al so increa se,owing to their dependence on climate, e speciallytemperature, of the re spective vector s mo sq uito-es, flies and snails (Kelly-Hope et al , 2008). Thevector-borne di sea ses include:

malaria,dengue,leishmania sis andschisto somia sis



It is expected that the incidence andmagnitude of infectiou s disea se effect s will

increa se as global temperature s rise. Forexample, it ha s been ob served since 1980,that a new di sea se ha s emerged, on average,every seven to eight month s (EmergingInfectiou s Disea ses, 2005).60% of the se emerging di sea ses are zoonotic,that i s, tran smiss ible between animal s andman.



The primary purpo se of early warning i s to enableearlier intervention and effective prevention andcontrol of epidemic s. A working framework for thedevelopment of system s that enable epidemicforeca sting, prevention, early detection and controlha s been developed and it s variou s component s andproce ss es te sted in a number of countrie s.There indeed exi st model s of malaria incidence thatincorporate monitored or predicted climate, andwhich can provide early warning s of epidemic s oneto five month s in advance in semi-arid area s.



Access to fre quently-updated climate information i s an important re quirement for the development of integrated early warning system s for climatesen sitive disea ses.The routine u se of such information within Africandisea se control programme s is, however, limitedmainly becau se of poor inter- sectoral collaboration s

between health and other sector s (includingmeteorology and agriculture) and the lack of systematic evidence concerning the co st-effectivene ss of the early warning system.



Fortunately, thi s is one of the key area s addre ss ed by the Libreville Declaration 11

Action point s (2008) and Implementation



Another major challenge facing Africa is the relativeweakne ss in disea se surveillance and reportingsystem s, which hamper the detection and control of epidemic s, making it difficult to obtain the long-term linked data set s on climate and di sea se that arenece ss ary to develop early warning system s. Duringmalaria epidemic s, for example, health facilitie s are

often overwhelmed and have to treat the wholepopulation in order to reduce the re servoir of thepara site within the population.



W hile the key factor s in the epidemiology of variou s disea ses may differ from di sea se to di sea se, the

ba sis of any epidemic early warning and re spon sesystem i s anchored on a framework of fiveintegrated component s: (1) vulnerabilityass ess ment and monitoring; (2) sea sonal climate

foreca sting; (3) environmental monitoring; (4)sentinel ca se surveillance; and (5) planning,preparedne ss and re spon se.



In the ca se of malaria model s, it is clear thattechnical and practical hurdle s still need to be

overcome before some of the model s can bewidely integrated into routine malaria-control strategie s.[Key step s on Local activity on malaria anddiarrhoeal di sea ses cited here]



Alteration s in rainfall, surface wateravailability and water quality a s a re sult of

climate change could affect the burden of water-related di sea ses.W ater-related di sea ses can be cla ss ified byroute of tran smiss ion, thu s distingui shingbetween water-borne (inge sted) and water-washed di sea ses (that i s tho se cau sed by lackof hygiene).



The IPCC (AR4) state s four maincon sideration s for evaluating the relation ship

between health outcome s and expo sure tochange s in rainfall, water availability andquality. The se are(i) linkages between water availability,hou sehold acce ss to improved water, and thehealth burden due to diarrhoeal di sea ses;



(ii) the role of extreme rainfall in facilitatingwater-borne outbreak s of disea ses through

piped water supplie s or surface water;(iii) effects of temperature and runoff onmicrobiological and chemical contaminationof coa stal, recreational and surface water s;and(iv) direct effect s of temperature on theincidence of diarrhoeal di sea se.



Floods

Floods, a natural weather di saster and one of the

manife station s of climate change, are expected torise in inten sity and fre quency.Besides the immediate impact s of thi s naturaldisaster, population s with poor sanitation

infrastructure and high burden s of infectiou s disea se often experience increa sed rate s of diarrhoeal di sea ses after flood event s.



Vector organi sms that do not regulate theirinternal temperature s and are therefore

sen sitive to external temperature andhumidity tran smit many important infectiou s disea ses.C limate change may alter the di stribution of

vector specie s (increa sing or decrea sing)depending on whether condition s arefavourable or unfavourable for their breedingplace s.



C hange s in climate that can affect thepotential tran smiss ion of vector-borne

infectiou s disea ses include temperature,humidity, altered rainfall, soil moisture andrising sea level.



In malaria dynamic s, both para site and vector are affectedby rainfall and temperature. Rainfall is widely documentedas a limiting factor for mo sq uito population s.Decadal decrea ses in rainfall have indeed been a ss ociatedwith reduction s in tran smiss ion, while inter-annual malariavariability is climate-related in specific eco-epidemiological zone s (AR4) ass ociation s between inter-annual variability in temperature and malaria tran smiss ionin the African highland s. Malaria admi ss ions in the

highland area s of Kenya have been a ss ociated with rainfalland unu sually high maximum temperature s 3-4 month s tothe outbreak (Githeko and Ndegwa, 2001).



There are clear a ss ociation s between inter-annual variability in temperature and malaria

tran smiss ion in the African highland s.Malaria admi ss ions in the highland area s of Kenya have been a ss ociated with rainfall andunu sually high maximum temperature s 3-4month s to the outbreak (Githeko andNdegwa, 2001).



Epidemic malaria i s a public-health problemin mo st area s in Africa, with programme s in

place to reduce the morbidity and mortalityass ociated with the se epidemic s.Some projection s sugge st that climatechange may facilitate the spread of malariafurther up some highland area s.



Therefore, programme s should not onlycontinue their current focu s, but should al so

con sider where and when to implementadditional surveillance to identify and preventepidemic s if the Anoph eles vector change s its range.



Thank you all

Climate and Health Early Warning

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