A Mixed infection of Plasmodium falciparum and Plasmodium malariae: the first report of a Plasmodium malariae infection after 37 years of its absence in Sri Lanka

Abstract

Malaria has been endemic in Sti Lanka for several centuries. Currently, only Plasmodium falciparum and P. vivax are present in the country. P. malariae infections have not .been reported in Sri Lanka since 1969. The objective is to determine the presence of malaria species in a patient returned from Malawi. The clinical history of intermittent high fever for 2 weeks accompanied by severe headache, myalgia, arthralgia, vomitimg, loss of appetite and backache with ictetus and mild hepatosplenomegaly suggested malaria in this 51 year old patient. Apart from the basic biochemical investigations, presence of malarial species was determined by light microscopy and confirmed by Real-Time Polymerase Chain Reaction (PCR) technology. Biochemical investigations showed a high serum bilirubin (4.8 mg/di) and liver enzyme (SGOT = >125 units, SGPT = >250 units) levels. Serum haemoglobin level (12.8 g%) was normal. Except for the presence of ptoteinuria (albumin = ++), bile (+) and red blood corpuscles (RBC) in his urine, renal functions were normal. Microscopical examination of Giemsa stained thin and thick blood smears showed an asexual parasite density of 120,000 per ul of blood. Infected RBCs were not enlarged, The presence of double-chromatin and applique form trophozoites, occasionally invading multiple RBCs suggested P. falciparum infection. In addition, there were characteristic band form trophozoites of P. malariae. Real-Time PCR protocol confirmed the presence of both P. falciparum and P. malariae in this patient. This is the first case of P. malariae reported in Sri Lanka after 4 decades, though the infection had been acquired from Malawi. Clinical and biochemical evidence indicated liver dysfunction and a transient glomerulonephritis, both of which subsided after treatment with quinine. This case report emphasizes the need of physicians to be more vigilant about the presence of malaria among immigrants, despite the drastic reduction of malaria in the country in recent years. Hence, this report highlights the importance of a proper programme in Sri Lanka to screen immigrants for infectious diseases.