Question

A 44-year-old man is seen at a physician’s office in the Metro Manila, during a week-end. The patient was travelled in Palawan last week which is known to be an endemic site for a vector borne disease. He did not taken up any prophylaxis during the said travel. Upon checking, the blood smear at that time was reported by the hospital as positive for malaria, species undetermined. He was then treated with 2 days of IV fluids (nature unknown) and tablets (nature unknown), and recovered. The patient now presents with a history of low grade fever for the past few days, with no other symptoms. A blood smear is taken and examined at a hospital laboratory in which she sees 4 parasites per 1000 red blood cells, with multiple rings inside RBC and presence of sausage form gametocyte.

Questions to answer:

1. What is the probable parasite based on blood smear?

1.1 Why do you think that is the probable parasite?

1.2 Differentiate the vector associated with Plasmodium and Babesia

A. Plasmodium vivax                                                                      B.Plasmodium falciparum

C. Plasmodium ovale                                                                      D. Plasmodium malaria

E. Babesia microti

2. Thick and Thin smear are being utilized in the identification of Plasmodium and Babesia. Describe the uses and its possible limitation.

3. Kindly fill up the table to differentiate the different Plasmodium spp.

P. falciparum               P. vivax           P. malariae          P. ovale

RBC invaded Ring

Form Developing

Trophozoite

Schizont              

Gametocyte

Answer 1

Patient visit the doctor after returning from endemic area of vector born disease. From the blood smear it is evident that this is malarial parasite.

smear shows multiple ring forms of parasite in RBC. Gametocyte of the parasite is sausage shape. This is characteristic of plasmodium falciparum.

Characteristics- affect all stages of RBC. Ealy stages of trophozites and gametocytes seems as rings inside RBC. Gametocytes are banana shape.

Hence the parasite is plasmodium falciparum

1.2

Vector

details

p. vivax

Anopheles mosquito

Life span – 2-3 weeks

Breed in natural water collection

When resting stomach area of mosquito pointing upwards

Larva- wigglers, seen as parallel to water surface

p.falceparum

p.ovale

p. malaria

Babesia microti

Ixodes tick

Ixodes scapularis

Require blood meal

2. thick and thin smear

Use

Limitation

Thick- reliable because large volume of blood examined under microscopy.

When parasite is sandy parasite may found 20 time rapid in thick than thin smear.

Thin

Help to identify species

Advantages

High sensitivity

Can detect parasite at low densities

Help to quantify parasite load  

Invasive procedure

Time consuming

Individual variations can occur

3. refer the diagram uploaded

falciparum

vivax

malaria

ovale

Ring form-

Trophozoit

Schizont

Gametocyte