Dr Prof. Jamil Ahmed

1. COMMUNICABLECOMMUNICABLE
&&
NON COMMUNICABLENON COMMUNICABLE
DISEASESDISEASES
DENGUE FEVERDENGUE FEVER
Dr. Jamil Ahmad
MBBS, PGDHP&M, CDM (Japan), HRSA (Cairo)

2. DENGUE A MAJOR GLOBAL HEALTHDENGUE A MAJOR GLOBAL HEALTH
PROBLEMPROBLEM
 Dengue in recent years has become a majorDengue in recent years has become a major
international public health concern. Dengue is found ininternational public health concern. Dengue is found in
tropical and sub-tropical regions around the world,tropical and sub-tropical regions around the world,
predominantly in urban and semi-urban areas.predominantly in urban and semi-urban areas.
 Dengue Haemorrhagic fever (DHF) a potentially lethalDengue Haemorrhagic fever (DHF) a potentially lethal
complication was first recognized in the 1950s duringcomplication was first recognized in the 1950s during
the dengue epidemics in the Philippines and Thailand,the dengue epidemics in the Philippines and Thailand,
but today DHF affects most Asian countries and hasbut today DHF affects most Asian countries and has
become a leading cause of hospitalization and deathbecome a leading cause of hospitalization and death
among children.among children.

3.  The global prevalence of dengue has grownThe global prevalence of dengue has grown
dramatically in recent decades. The disease is nowdramatically in recent decades. The disease is now
endemic in more thanendemic in more than 100100 countries incountries in AfricaAfrica, the, the
AmericasAmericas, the, the Eastern MediterraneanEastern Mediterranean ,, South-South-
east Asiaeast Asia and theand the Western PacificWestern Pacific ..
 South-east Asia and the Western Pacific are mostSouth-east Asia and the Western Pacific are most
seriously affected.seriously affected.
 Before 1970 onlyBefore 1970 only nine countriesnine countries had experiencedhad experienced
DHF epidemics, a number that hadDHF epidemics, a number that had increased moreincreased more
than four-fold by 1995than four-fold by 1995 ..
 Some 2500 million people -Some 2500 million people - two fifthstwo fifths of the world'sof the world's
population - are now at risk from dengue.population - are now at risk from dengue. WHOWHO
currently estimates there may be 50 millioncurrently estimates there may be 50 million
cases of dengue infection worldwide everycases of dengue infection worldwide every
year.year.

4.  InIn 20012001 alone, there were more thanalone, there were more than 609000609000
reported cases of dengue in the Americas, ofreported cases of dengue in the Americas, of
whichwhich 1500015000 cases were Denguecases were Dengue
Haemorrhagic Fever. This is greater thanHaemorrhagic Fever. This is greater than
doubledouble the number of dengue cases whichthe number of dengue cases which
were recorded in the same region inwere recorded in the same region in 19951995..
 Not only is the number of cases increasing asNot only is the number of cases increasing as
the disease is spreading to new areas,the disease is spreading to new areas, butbut
explosive outbreaks are occurringexplosive outbreaks are occurring ..
 InIn 20012001, Brazil reported over 390000 cases, Brazil reported over 390000 cases
including more thanincluding more than 670 cases of DHF670 cases of DHF ..

5. Distribution Western Hemisphere

6. Distribution of dengue, Eastern Hemisphere

7.  An estimated 500,000 cases of DHF requireAn estimated 500,000 cases of DHF require
hospitalization each year, of whom a very large proportionhospitalization each year, of whom a very large proportion
are children. At least 2.5% of cases die, although caseare children. At least 2.5% of cases die, although case
fatality could be twice as high.fatality could be twice as high.
 Without proper treatment, DHF case fatality rates canWithout proper treatment, DHF case fatality rates can
exceed 20%. With modern intensive supportive therapy,exceed 20%. With modern intensive supportive therapy,
such rates can be reduced to less than 1%.such rates can be reduced to less than 1%.
 The spread of dengue is attributed to expandingThe spread of dengue is attributed to expanding
geographic distribution of the four dengue viruses and ofgeographic distribution of the four dengue viruses and of
their mosquito vectors, the most important of which is thetheir mosquito vectors, the most important of which is the
predominantly urban speciespredominantly urban species Aedes aegyptiAedes aegypti..
 A rapid rise in urban populations is bringing greaterA rapid rise in urban populations is bringing greater
numbers of people into contact with this vector, especiallynumbers of people into contact with this vector, especially
in areas that are favourable for mosquito breeding, e.g.in areas that are favourable for mosquito breeding, e.g.
where household water storage is common and wherewhere household water storage is common and where
solid waste disposal services are inadequatesolid waste disposal services are inadequate

8.  In Asia and Amrecas theIn Asia and Amrecas the Aedes aegyptiAedes aegypti breedsbreeds
primarily in man-made containers like:primarily in man-made containers like:
 Earthenware jars,Earthenware jars,
 Metal drums andMetal drums and
 Concrete cisterns used for domestic waterConcrete cisterns used for domestic water
storage.storage.
 Discarded plastic food containersDiscarded plastic food containers
 Used automobile tyres and other items thatUsed automobile tyres and other items that
collect rainwater.collect rainwater.
 In Africa it also breeds extensively in naturalIn Africa it also breeds extensively in natural
habitats such as tree holes and leaf axils.habitats such as tree holes and leaf axils.

9.  In recent years,In recent years, Aedes albopictusAedes albopictus, a secondary, a secondary
dengue vector in Asia, has become establisheddengue vector in Asia, has become established
in the United States, several Latin American andin the United States, several Latin American and
Caribbean countries, in parts of Europe.Caribbean countries, in parts of Europe.
 The rapid geographic spread of this species hasThe rapid geographic spread of this species has
been largely attributed to the international tradebeen largely attributed to the international trade
in used tyres.in used tyres.

11. Dengue SyndromeDengue Syndrome
 Dengue fever and dengue hemorrhagic fever (DHF) areDengue fever and dengue hemorrhagic fever (DHF) are
viral diseases transmitted byviral diseases transmitted by AedesAedes mosquitoes, usuallymosquitoes, usually
Aedes aegyptiAedes aegypti..
 There are four types of this virus (serotypes 1 to 4) andThere are four types of this virus (serotypes 1 to 4) and
are closely related to one another.are closely related to one another.
 Recovery from infection by one provides lifelongRecovery from infection by one provides lifelong
immunity against that serotype but confers only partialimmunity against that serotype but confers only partial
and transient protection against subsequent infection byand transient protection against subsequent infection by
the other three.the other three.
 There is good evidence that sequential infectionThere is good evidence that sequential infection
increases the risk of more serious disease resulting inincreases the risk of more serious disease resulting in
DHF.DHF.

12.  Dengue viruses are capable of infecting humans andDengue viruses are capable of infecting humans and
causing disease. These infections may becausing disease. These infections may be
symptomatic, or may lead to:symptomatic, or may lead to:
1.1. ““Classical” dengue feverClassical” dengue fever
2.2. Dengue Haemorrhagic fever without shockDengue Haemorrhagic fever without shock
3.3. Dengue Haemorrhagic fever with shockDengue Haemorrhagic fever with shock

13. DENGUE VIRUS INFECTION
Asymptomatic Symptomatic
Undiffrentiated fever
(viral syndrome)
Dengue fever
(syndrome)
Dengue
Haemorrhagic fever
No Shock
Dengue Shock
Syndrome (DSS)
(Plasma
leakage)Dengue Fever
Dengue
Haemorrhagic fever

14. CLASSICAL DENGUE FEVERCLASSICAL DENGUE FEVER
 Reservoir both man and mosquitoReservoir both man and mosquito
The mosquito becomes infective by feeding on theThe mosquito becomes infective by feeding on the
patient from the day before onset to the 5patient from the day before onset to the 5thth
day ofday of
illness.illness.
After an extrinsic incubation period of 8-10 days theAfter an extrinsic incubation period of 8-10 days the
mosquito becomes infective and is able to transmitmosquito becomes infective and is able to transmit
infection.infection.
The illness is characterized by an incubation periodThe illness is characterized by an incubation period
of 3-10 days.of 3-10 days.
1.1. Onset is sudden with chills and high fever.Onset is sudden with chills and high fever.
Temperature rises quickly as high as 104° F (40° C),Temperature rises quickly as high as 104° F (40° C),
with relative bradycardia and hypotension.with relative bradycardia and hypotension.

15. 2.2. Reddened eyesReddened eyes
3.3. Intense muscles and joint painsIntense muscles and joint pains
4.4. A flushing or pale pink rash comes over the face and thenA flushing or pale pink rash comes over the face and then
disappears. The glands (lymph nodes) in the neck and groindisappears. The glands (lymph nodes) in the neck and groin
are often swollenare often swollen
5.5. Fever lasts 2-4 days rarely more than 7 days.Fever lasts 2-4 days rarely more than 7 days.
6.6. Recovery is completeRecovery is complete
7.7. Case fatality is very lowCase fatality is very low

16. Dengue Haemorrhagic FeverDengue Haemorrhagic Fever
Dengue hemorrhagic fever is a more severe form of the viralDengue hemorrhagic fever is a more severe form of the viral
illness. Caused by more than one dengue viruses. It is due toillness. Caused by more than one dengue viruses. It is due to
double infection with dengue virus. The first infectiondouble infection with dengue virus. The first infection
sensitizes the patient and the second appears to producesensitizes the patient and the second appears to produce
immunological catastrophe.immunological catastrophe.
Manifestations include:Manifestations include:
 Headache, high fever (continuous and lasting 2-7 days)Headache, high fever (continuous and lasting 2-7 days)
 Rash, andRash, and evidence of hemorrhage in the body (Petechiae)evidence of hemorrhage in the body (Petechiae)
 Bleeding in the nose or gums,Bleeding in the nose or gums,
 Black stools, or easy bruising are all possible signs ofBlack stools, or easy bruising are all possible signs of
hemorrhage.hemorrhage.
 This form of dengue fever can be life-threatening or evenThis form of dengue fever can be life-threatening or even
fatal.fatal.

17. Skin rash
Symptoms

18.  THERE IS NO DRUG FOR DENGUE.THERE IS NO DRUG FOR DENGUE.
 To prevent dengue fever, you must prevent theTo prevent dengue fever, you must prevent the
breeding of its carrier, the Aedes mosquitoes.breeding of its carrier, the Aedes mosquitoes.
TreatmentTreatment
Because dengue is caused by a virus, there is noBecause dengue is caused by a virus, there is no
specific medicine or antibiotic to treat it.specific medicine or antibiotic to treat it.
For typical dengue, the treatment is purely concernedFor typical dengue, the treatment is purely concerned
with relief of the symptoms (symptomatic).with relief of the symptoms (symptomatic).
Rest and fluid intake for adequate hydration is important.Rest and fluid intake for adequate hydration is important.

19. ImmunizationImmunization
 Vaccine development for dengue and DHF is difficultVaccine development for dengue and DHF is difficult
because any of four different viruses may causebecause any of four different viruses may cause
disease.disease.
 Nonetheless, progress is being made in theNonetheless, progress is being made in the
development of vaccines that may protect against alldevelopment of vaccines that may protect against all
four dengue viruses. Such products may becomefour dengue viruses. Such products may become
available for public health use within several years.available for public health use within several years.

21.  The mosquito flourishes during rainy seasons but canThe mosquito flourishes during rainy seasons but can
breed in water-filled flower pots, plastic bags, and cansbreed in water-filled flower pots, plastic bags, and cans
year-round.year-round.
 One mosquito bite can inflict the disease.One mosquito bite can inflict the disease.
 Under optimal conditions, the egg of an Aedes mosquitoUnder optimal conditions, the egg of an Aedes mosquito
can hatch into a larva in less than a day.can hatch into a larva in less than a day.
 The larva then takes about four days to develop in a pupa,The larva then takes about four days to develop in a pupa,
from which an adult mosquito will emerge after two days.from which an adult mosquito will emerge after two days.
 Three days after the mosquito has bitten a person andThree days after the mosquito has bitten a person and
taken in blood, it will lay eggs, and the cycle begins again.taken in blood, it will lay eggs, and the cycle begins again.

22. Facts about the mosquitoFacts about the mosquito
 Only the female aedes mosquito bites as it needsOnly the female aedes mosquito bites as it needs
the protein in blood to develop its eggs.the protein in blood to develop its eggs.
 The mosquito becomes infective approximately 7The mosquito becomes infective approximately 7
days after it has bitten a person carrying the virus.days after it has bitten a person carrying the virus.
 This is theThis is the extrinsic incubation periodextrinsic incubation period , during, during
which time the virus replicates in the mosquito andwhich time the virus replicates in the mosquito and
reaches the salivary glands.reaches the salivary glands.

23.  Peak biting is at dawn and dusk.Peak biting is at dawn and dusk.
 The average lifespan of an Aedes mosquito in NatureThe average lifespan of an Aedes mosquito in Nature
is 2 weeks.is 2 weeks.
 The mosquito can lay eggs about 3 times in itsThe mosquito can lay eggs about 3 times in its
lifetime, and about 100 eggs are produced each time.lifetime, and about 100 eggs are produced each time.
 The eggs can lie dormant in dry conditions for up toThe eggs can lie dormant in dry conditions for up to
about 9 months, after which they can hatch if exposedabout 9 months, after which they can hatch if exposed
to favourable conditions, i.e. water and food.to favourable conditions, i.e. water and food.

24. Potential Breeding Sites

36. PreventionPrevention
 The application of appropriate insecticides to larvalThe application of appropriate insecticides to larval
habitats.habitats.
 During outbreaks, emergency control measures mayDuring outbreaks, emergency control measures may
also include the application of insecticides as:also include the application of insecticides as:
 space sprays to kill adult mosquitoes using portablespace sprays to kill adult mosquitoes using portable
or truck-mounted machines or even aircraft.or truck-mounted machines or even aircraft.
 However, the killing effect is only transient, variable inHowever, the killing effect is only transient, variable in
its effectiveness because the aerosol droplets mayits effectiveness because the aerosol droplets may
not penetrate indoors to microhabitats where adultnot penetrate indoors to microhabitats where adult
mosquitoes are hiding.mosquitoes are hiding.

38. Dengue Prevention ChecklistDengue Prevention Checklist
 To prevent the spread of dengue fever, we mustTo prevent the spread of dengue fever, we must
first prevent the breeding of its vector, the Aedesfirst prevent the breeding of its vector, the Aedes
mosquitoes.mosquitoes.
 The Aedes mosquito is easily identifiable by itsThe Aedes mosquito is easily identifiable by its
distinctive black and white stripes on their body.distinctive black and white stripes on their body.
It prefers to breed in clean, stagnant water easilyIt prefers to breed in clean, stagnant water easily
found in our homes.found in our homes.
 We can get rid of the Aedes mosquito byWe can get rid of the Aedes mosquito by
frequently checking and removing stagnantfrequently checking and removing stagnant
water in our premises.water in our premises.

39. CHECKLISTCHECKLIST
At all timesAt all times
 Turn pails and watering cans over and storeTurn pails and watering cans over and store
them under shelter.them under shelter.

40.  Remove water in plant pot plates. CleanRemove water in plant pot plates. Clean
and scrub the plate thoroughly to removeand scrub the plate thoroughly to remove
mosquito eggs. Avoid the use of plant potmosquito eggs. Avoid the use of plant pot
plates, if possible.plates, if possible.

41.  Loosen soil from potted plants to prevent theLoosen soil from potted plants to prevent the
accumulation of stagnant water on the surface ofaccumulation of stagnant water on the surface of
the hardened soil.the hardened soil.
 Do not block the flow of water in scupper drains.Do not block the flow of water in scupper drains.

42.  Cover rarely used gully traps. Replace theCover rarely used gully traps. Replace the
gully trap with non-perforated ones andgully trap with non-perforated ones and
install anti-mosquito valves.install anti-mosquito valves.

44.  No tray or receptacles should be placed beneath andNo tray or receptacles should be placed beneath and
or/ on top of any air-conditioning unit so as not to createor/ on top of any air-conditioning unit so as not to create
a condition favourable for mosquito breeding. a condition favourable for mosquito breeding.
Every other dayEvery other day
Change water in flower vases. Clean and scrub theChange water in flower vases. Clean and scrub the
inner sides of vases. Wash roots of flowers and plantsinner sides of vases. Wash roots of flowers and plants
thoroughly as mosquito eggs can stick to them easily.thoroughly as mosquito eggs can stick to them easily.

45. Once a weekOnce a week
 Clear fallen leaves and stagnant water in your scupperClear fallen leaves and stagnant water in your scupper
drains and garden.drains and garden.
These leaves could collect water or cause blockages toThese leaves could collect water or cause blockages to
the drains, thus resulting in the build-up of stagnant water.the drains, thus resulting in the build-up of stagnant water.
 Clear any stagnant water in your air cooler unit.Clear any stagnant water in your air cooler unit.
Once a monthOnce a month
Add prescribed amounts of sand granular insecticide intoAdd prescribed amounts of sand granular insecticide into
vases, gully traps and roof gutters, even if they are dry.vases, gully traps and roof gutters, even if they are dry.

46. ThanksThanks