It is a protozoal disease caused by protozoa plasmodium and transmitted by infective female anopheles mosquito. Typical attacks have 3 stages –
- Chill stage
- Heat stage
- Sweat stage
AGENT FACTOR
Agent : Malaria is caused due to 4 distinct species of malarial parasite – P.vivax, P.falciparum, P.malarie, P.ovale. In India, 70% of malaria is due to p.vivax.
Reservoir of infection : Chimpanzees in tropical Africa. A child or adult harbouring sexual form of parasite.
Period of communicability : Malaria is communicable as long as mature, viable gametocytes exist in circulating blood in sufficient density to infect vector mosquito.
P.vivax – 4-5 days after appearance of a sexual partner.
P.falciparum – 10-12 days after appearance of a sexual partner.
HOST FACTOR
Age : All ages, new born infants show considerable resistance to infection by P.falciparum.
Sex : Male preponderance
Race : Individual with sickle cell trait are protected
Pregnancy : Risk is increased
Socio-economic development : developing countries
Population mobility : Increases the risk
Occupation : Rural disease related to agricultural parasite
Human habit : Sleeping, nomadism
Housing : Ill-ventilated and ill lighted houses.
ENVIRONMENTAL FACTORS
Season : Maximum from July to November
Temperature : 20o – 30o C
Humidity : Relative humidity of 60%
Rainfall : Moderate rainfall causes increase in breeding of parasite, heavy rainfall destroys the breeding ground.
Attitude : Anopheline mosquito does not survive beyond 2000-2500 mtr.
MODE OF TRANSMISSION
Inoculation of female anopheles mosquito of sporozoite in human being.
INCUBATION PERIOD
P.falciparum : 12 (9-14 days)
P.vivax : 14 (8-17 days)
P.ovale : 28 (18-40 days)
P.malarie : 17 (16-18 days)
