Epidemiological Features and Diagnosis of Malaria Disease

Epidemiological Features and Diagnosis of Malaria Disease

 Definition of Malaria Disease:

Malaria is a mosquito-borne infectious disease which affects humans and other animals caused by parasitic protozoans (a group of single-celled microorganisms) belonging to the Plasmodium type. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches.

Diagnosis of malaria disease
Fig: Diagnosis of malaria disease

Malaria is an infectious disease caused by plasmodium and transmitted by the bite of female anopheles mosquito, characterized by-fever, anemia, splenomegaly etc. Children under 5 years of age are one of the most vulnerable groups affected by malaria, accounting for a large portion of the estimated 445 000 malaria deaths around the world in 2016.

Epidemiological Features of Malaria Disease:

1. Agent factors:

a) Agent: Malaria in man is caused by 4 distinct species of malaria parasite.

  • Plasmodium vivax,
  • Plasmodium falciparum,
  • Plasmodium malariae,
  • Plasmodium ovaleale.

b) Reservoir of infection: Human

c) Period of communicability: Malaria is communicable as long as gametocytes exist in the blood to infect vector mosquito.

2. Host factors:

  • Age: Malaria affects all ages
  • Sex: Male are more exxposed than female
  • Pregnancy: The risk
  • Social and economic factor: More in underdeveloped countries
  • Housing: More in all ventilated and ill lighted house
  • Occupation: More in agriculture practitioner
  • Human habits sleeping out of house and mosquito net.

3. Environmental factors:

  • Season: Maximum prevalence is from July to November
  • Temperatures: 20°C-30°C
  • Humidity: 60% Or
  • Rain fall: Necessary for breeding

4. Mode of transmission:

a. Vector transmission: Infected female anopheles mosquito

b. Direct transmission:

  • Blood transmission,
  • Infected needles,
  • Congenițal-very very rare.

5. Incubation period:
Varies according to species–

  • 12 (9- 14) days for P. falciparum
  • 14 (8-17) days for P. vivax
  • 28 (18–40) days for P. malariae
  • 17 (16 – 18) days for P. ovale

History and Laboratory Diagnosis of Malaria Disease:


a) Patient may give H/O travel of malarious locality

b) Onset is insidious with malaise, headache, vomiting

c) Fever:

  • No particular pattern,
  • Cold, hot and sweating stages are seldom found,
  • Not so high temperatures.

d) Cough and mild diarrhea

e) Weakness

f) Patient may present with complication of the disease:

  • Unconsciousness,
  • Acute renal failure,
  • Black water fever,
  • Acute renal respiratory syndrome,
  • Septicemia.

On examination (O/E):

  • Patient anemia,
  • Jaundice may present,
  • Increase Temperature,
  • Hepato splenomegaly.

Laboratory Diagnosis of Malaria Disease:

1. Direct evidences:

  • Thick film: To detect the presence of parasite,
  • Thin film: To detect the species of parasite.

2. Indirect evidences:

  • Serological test,
  • Blood for TC, DC, ESR, Hb%,
  • Liver function test,
  • Examination of urine.

More questions related to this article:

  1. What is malaria?
  2. What do you mean by malaria?
  3. Write down the epidemiological features of malaria.
  4. How will you diagnose a case of malaria?
  5. Write down the laboratory diagnosis of malaria.
  6. Write down the history and investigation of malaria.

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