2 Malaria Epidemiology

K.A.ABINAYAPRE-FINAL YEAR

EPIDEMIOLOGIC INTERACTIONS

AGENT FACTORS MALARIA IS CAUSED BY 4 DIFF SPECIES OF PLASMODIUM GEOGRAPHIC DISTRIBUTION OF PLASMODIA

IN INDIA:

P.MALARIAE-KARNATAKAP.OVALE:TROPICAL AFRICA,VIETNAM

INFECTION % PLASMODIUM SPECIES

70% P.VIVAX

25-30% P.FALCIPARUM

4-8% MIXED

LESS THAN 1% P.MALARIAE

LIFE HISTORY OF MALARIAL PARASITE

ANIMAL RESERVOIRHUMAN RESERVOIRCHILDREN AS RESERVOIRS

CONDITIONS TO SERVE AS A RESEROVIR:

BOTH SEXES OF GAMETOCYTES IN BLOODGAMETOCYTES MUST BE MATUREGAMETOCYTES MUST BE VIABLEPRESENT IN SUFFICIENT DENSITY-AT

LEAST 12 /cu.mm OF BLOOD

AS LONG AS MATURE, VIABLE GAMETOCYTES IN BLOOD

GAMETOCYTES IN SUFFICIENT DENSITY

VIVAX INFECTION:4-5 DAYS

FALCIPARUM INFECTION :10-12 DAYS

RELAPSES:

•VIVAX AND OVALE MALARIA•3 YRS AFTER FIRST ATTACK•ORIGINAL SPOROZOITE INDUCED LIVER SCHIZONTS

RECURRENCES:• FALCIPARUM AND P.MALARIAE• CHRONIC BLOOD INFECTION • ERYTHROCYTIC SCHIZOGONY LOW LEVEL PERSISTENCE

AGE:*ALL AGES*NEW BORNS-CONSIDERABLE RESISTANCE

SEX:MALES

RACE:SICKLE CELL TRAIT

DUFFY NEGATIVE

PREGNANCY:IUD OF FETUS,PRE MATURE LABOR,ABORTION

SOCIO ECONOMIC DEVELOPMENT:DIS APPEARED IN DEVELOPED NATIONS

HOUSING:ILL VENTILATED AND ILL LIGHTED HOUSESSITE,TYPE OF CONSTRUCTION,NATURE OF WALLS-CONTROL PLANNING

POPULATION MOBILITY:INTERNAL MIGRATION

OCCUPATION:

HUMAN HABITS:SLEEPING OUTDOORS,REFUSAL TO SPRAYING,NOMADISM

IMMUNITY:• AQUIRED AFTER REPEATED EXPOSURE• IN ENDEMIC AREAS:• INFANTS BORN:• SPECIES SPECIFIC:• SEMI-IMMUNE INDIVIDUALS:

SEASONAL DISEASE:JULY TO NOVTEMPERATURE:

OPTIMAL TEMP:20-30 DEGREES CIF TEMP BELOW 16 DEGREES CTEMP >30 DEGREES C-LETHAL

HUMIDITY:RELATIVE HUMIDITY 60%

RAIN FALL:• INCREASES ATMOSPHERIC HUMIDITY• HEAVY RAIN- ADVERSE EFFECT• PARODOXICALLY, IN SRI LANKA-EPIDEMIC AFTER DROUGHTALTITUDE: NOT FOUND ABOVE 2000-2500 MMAN-MADE MALARIA:BURROW PITS,GARDEN POOLS, IRRIGATION CHANNELS etc

FEW INTERSTING FACTS ON ANOPHELES:

HOW DOES A MOSQUITO BITE???(DOES IT BITE?!!?)

WHY DOES A MOSQUITO NEED HUMAN BLOOD?

WHEN DOES ANOPHELES BITE MAN?

HOW FAR DO THE MOSQUITOES FLY?

HOW LONG DO THEY LIVE?

WHERE DO THEY HIDE?

WHERE DO THEY LAY EGGS?

•A. (A.) sacharovi•A. (C.) aconitus•A. (C.) annularis•A.(C.) culicifacies•A. (C.) fluviatilis•A. (C.) jeyporiensis•A. (C.) minimus•A. (C.) philippinensis•A. (C.) pulcherrimus•A. (C.) stephensi malariaspecies.html•A. (C.) sundaicus•A. (C.) superpictus•A. (C.) tessellatus•A. (C.) varuna

FACTORS DETERMINING VECTORIAL IMPORTANCEDENSITY

CRITICAL DENSITYAN.CULICIFACIES-HIGH DENSITYAN.FLUVIATILIS-LOW DENSITY

LIFE SPANVECTOR-SHOULD LIVE ATLEAST 10 TO 12 DAYS AFTER AN

INFECTIVE BLOOD MEAL.STRATEGY IN ERADICATION

CHOICE OF HOSTANTHROPOPHILICZOOPHILIC

RESTING HABITENDOPHILYEXOPHILY

BREEDING HABITSMOVING WATER-AN.FLUVIATILISBRACKISH WATER-AN. SUNDAICUSSTAGNANT WATER-AN.STEPHENSI

TIME OF BITING

VECTORIAL CAPACITYDENSITY OF THE VECTOR POPULATIONSUSCEPTIBILITY TO INFECTIONLIFE SPANPROBABILITY OF FEEDING ON MAN

RESISTANCE TO INSECTICIDES

VECTOR

DIRECT

CONGENITAL

VECTOR TRANSMISSIONCERTAIN SPECIES OF INFECTED FEMALE AN. MOSQUITOES

DIRECT TRANSMISSIONACCIDENTALLY BY I.M. OR I.V.

PARASITES SURVIVE ATLEAST 14 DAYS IN BLOOD STORED AT -4°C

PERSONS WHO HAVE LIVED IN AN ENDEMIC AREA AND

THOSE WHO HAD MALARIA SHOULD NOT BE ACCEPTED AS BLOOD DONORS UNTIL 3 YEARS

CONGENITAL TRANSMISSION