372 Annals of Saudi Medicine, Vol 22, Nos 5-6, 2002 MALARIA: HEMATOLOGICAL ASPECTS Layla A.M. Bashawri, FCP; Ahmed A. Mandil, DrPH; Ahmed A. Bahnassy, PhD; Mirghani A. Ahmed, MD Inspite of intensive worldwide efforts to reduce its transmission, malaria remains the most serious and widespread protozoal infection of humans. Over 40% of the world’s population are at risk of contracting malaria, which is endemic in 91 countries, mostly developing. 1 Malaria has long featured prominently in the grey area between parasitology and hematology. In a classical European textbook of hematology published in the 1930s, malaria was defined as a “typical blood disease” characterized by fever, anemia and splenomegaly. 2 It is currently considered a typical example of a hemolytic anemia in more recent hematology textbooks, due to an acquired extra-corpuscular cause. As parasites of the blood for the majority of their complex life cycle, they expectedly induce hematological alterations. The hematological abnormalities that have been reported to invariably accompany infection with malaria include anemia, thrombocytopenia, splenomegaly, and mild-to-moderate atypical lymphocytosis and rarely disseminated intravascular coagulation (DIC). 3,4 There have also been reports of leucopenia and leucocytosis. 3-5 Other hematological reactions to malaria that have been reported, include neutropenia, eosinophilia, neutrophilia and monocytosis. 6,7 Some controversies appear to exist however. Many of the studies on the hematological abnormalities have been conducted in endemic countries, some only in children and some only in severe malaria patients. 6,8-10 Relatively few studies have been done among non-immune or semi-immune travelers returning from endemic areas or patients returning from their endemic countries. 3,11,12 The aim of this study was to investigate and find the hematological changes that may occur in acute malaria infection in non-immune and semi-immune patients returning from endemic areas. Materials and Methods The study design utilized in this review was a retrospective clinical case series study. All confirmed From the Departments of Pathology and Family and Community Medicine, College of Medicine, King Faisal University, Dammam, Saudi Arabia. Address reprint requests and correspondence to Dr. Bashawri: Consultant Hematopathologist, King Fahd Hospital of the University, P.O Box 2208, Saudi Aramco, Al Khobar 31952, Saudi Arabia Accepted for publication 20 June 2002. Received 08 October 2001. cases of malaria who presented to King Fahd Hospital of the University (KFHU) at Al-Khobar in the Eastern Province of Saudi Arabia, between January 1988 and December 1999, were included in the study. A case was defined as a positive thin and/or thick blood film recorded in the Hematology Department laboratory records. A specially designed form of three sections was used for the purpose of these studies. Section A (basic demographic data): included variables as age, sex, residence, education, occupation, and travel history to an endemic area. Section B (clinical data): inquired about fever pattern, presence of jaundice, organomegaly and lymphadenopathy. Section C (hematological data): recorded information about blood counts, complete blood counts (CBC), plasmodium species and the parasite level in some cases. CBC were performed using an automated Coulter counter STKS model and WBC differential was done on almost all the cases where CBC was done. All malaria-positive smears were reviewed by a hematologist for confirmation, identification of species, review of smear for platelet count, and in some cases, estimation of parasite level. Due to the different nationalities encountered, normal values (reference ranges) for the hematological findings were based on recommendations by Dacie and Lewis. 13 The forms were completed by abstracting the relevant information from the medical records of the malaria cases diagnosed at KFHU during the specified period. Data was entered and analyzed using SPSS version 7.0. 14 Statistical analyses included descriptive statistics, bivariate analysis i.e., t-test, chi-square and analysis of variance (ANOVA). Level of significance was set at <0.05. Results A total of 727 patients fulfilled the inclusion criteria for the diagnosis of malaria. The mean age was 25.43±14.34 years, with a wide range (2 months to 74 years). There was a male predominance, with a male to female ratio of 3.15:1. Saudi patients comprised 305 (42%) while the remaining 422 (58%) were non-Saudis. The non-Saudi patients were of different nationalities (Indian, Pakistani, Sudanese, Sri Lankan, Yemenis, and few cases who were Indonesian, Nigerian, Turkish, and Ghanaian). The majority of cases (75%) had a positive travel history to an endemic area. The most common type of malaria was P. falciparum (54.2%),