Question
An adult male presents with complaints of high grade fever with chills and rigor for the past 6 days. On examination, patient has anemia and hepatosplenomegaly. Peripheral smear examination shows multiple ring forms.
- (a) What is the most probable diagnosis 1 mark(s)
- (b) Name the etiological agent and vector 2 mark(s)
- (c) Name the definitive host and intermediate host 2 mark(s)
- (d) Describe the laboratory diagnosis of this condition including the rapid diagnostic tests available e) Name the complications of this condition 3 mark(s)
Answer
a) Most probable diagnosis: Malaria — high-grade fever with chills/rigor, anaemia, hepatosplenomegaly, and ring forms on peripheral smear is classical.
b) Etiological agent and vector: Plasmodium species (P. vivax, P. falciparum, P. malariae, or P. ovale); vector: female Anopheles mosquito.
c) Definitive and intermediate hosts: Definitive host — female Anopheles mosquito (sexual/sporogonic cycle occurs here); Intermediate host — humans (asexual schizogonic cycle occurs here).
d) Laboratory diagnosis including rapid diagnostic tests
- Peripheral blood smear microscopy — gold standard; thick smear for screening, thin smear for species identification and parasitaemia quantification (Giemsa stain).
- Rapid diagnostic tests (RDTs) — immunochromatographic tests detecting histidine-rich protein-2 (HRP-2) (specific for P. falciparum) or pLDH/aldolase (pan-species) antigens; rapid, useful in field settings without microscopy access, giving results within 15–20 minutes.
- QBC (Quantitative Buffy Coat) method — fluorescence-based concentration technique, more sensitive than routine smear.
- PCR — highly sensitive/specific, detects low-level or mixed infections.
- Serology — detects past exposure, not useful for acute diagnosis.
e) Complications (particularly with P. falciparum): cerebral malaria (altered consciousness, seizures, coma), severe anaemia, acute kidney injury (including “blackwater fever”), hypoglycaemia, pulmonary complications (ARDS), placental malaria (in pregnancy), and disseminated intravascular coagulation/circulatory shock in severe disease.