CASE REPORT: DISSEMINATED INTRAVASCULAR COAGULATION COMPLICATED BY PERIPHERAL GANGRENE IN A RHESUS MACAQUE (MACACA MULATTA) EXPERIMENTALLY INFECTED WITH PLASMODIUM COATNEYI ALBERTO MORENO,* ANAPATRICIA GARCÍA, MÓNICA CABRERA-MORA, ELIZABETH STROBERT, AND MARY R. GALINSKI Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, Georgia; Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, Georgia Abstract. We report the first case of disseminated intravascular coagulation (DIC) complicated by peripheral gan- grene induced by Plasmodium coatneyi in rhesus monkeys. Ten days after experimental challenge, numerous petechiae were noted over the trunk and extremities, with polychromasia, severe anemia, thrombocytopenia, and moderate parasitemia. These changes were accompanied by elevated serum activity of blood urea nitrogen, creatinine, transam- inases, and creatinine phosphokinase. The animal received intravenous fluid support, artemether, and blood transfusion. Three days after treatment, the platelet counts returned to normal, and parasitemia was abated. However, several areas of skin discoloration with gangrenous tissue in the hands and the tail were observed. Coagulation profile showed elevated D-dimers and elevated levels of fibrinogen/fibrin degradation products with low levels of protein S functional activity. DIC with peripheral gangrene is very rare in Plasmodium-infected individuals. Our results indicate that the experimental model of P. coatneyi infection of rhesus monkeys is important for studies of malarial anemia and coagu- lopathy. INTRODUCTION Plasmodium is responsible for > 500 million clinical cases of malaria annually around the world. 1 Although natural human transmission of the simian malaria parasite Plasmodium knowlesi has been described, 2–4 four species of Plasmodium are generally attributed to human infection: P. falciparum, P. vivax, P. ovale, and P. malariae. P. falciparum is responsible for most of the severe cases of malaria estimated in 10% of the total number of clinical cases. Fatal cases have been es- timated between 1 and 3 million every year mainly among children younger than 5 years old. Ninety percent of these lethal cases are reported in sub-Saharan Africa. 5–7 These numbers have been maintained without dramatic changes ow- ing to the high prevalence of drug-resistant strains of parasites and failure of malaria control programs. 1 The World Health Organization (WHO) has established criteria to classify severe malaria. 8 The classification of clini- cal entities associated with the severity of the disease allows comparison in different epidemiologic settings. Severe ma- laria is defined by seven major syndromes: cerebral malaria, severe anemia, respiratory distress, renal failure, metabolic acidosis, hypoglycemia, and coagulopathy. Cerebral malaria and severe anemia are the most common complications in children and primigravidas. 9,10 This is in contrast with the frequent expression of pulmonary edema and renal failure in severe malaria cases in adults. 11 Parasite sequestration asso- ciated with a pro-inflammatory milieu is a critical pathogenic mechanism leading to multi-organ dysfunction in P. falci- parum malaria. 12 However, the precise molecular mecha- nisms associated with this and each of the individual syn- dromes of severe malaria are not fully understood. Non-human primates (NHPs) have been extensively used in malaria research as experimental animal models for drug and vaccine development. 13–16 The use of NHP for charac- terizing mechanisms associated with severe malaria is evident in recent studies. 17–20 We used simian malaria parasites in rhesus macaques to explore several biologic aspects of the complex parasite–host interactions involved in the pathogen- esis of multi-organ failure. P. coatneyi shares several morpho- logic and biologic features with P. falciparum. 21,22 Experi- mental infections of rhesus monkeys with P. coatneyi repro- duce several histopathologic findings reported in humans infected with P. falciparum. 17,18,23–25 We describe here the first case of disseminated intravascular coagulation (DIC) and peripheral gangrene in a rhesus macaque experimentally in- fected with P. coatneyi. Although platelet dysfunction and increased pro-coagulant activity is a common finding in se- vere malaria, DIC complicated with symmetrical peripheral gangrene is very rare. 26 The experimental design that we have used to follow-up infections provided us with a unique op- portunity to explore hematologic and immunologic param- eters associated with DIC. MATERIALS AND METHODS Study design and clinical laboratory assays. RIp-8, a 4-year- old male rhesus monkey (Macaca mulatta), was born and raised at the Yerkes National Primate Research Center. This animal was part of an experimental protocol designed to evaluate anemia induced by simian malaria parasite infections (unpublished data). Procedures used were approved by the Emory University’s Institutional Animal Care and Use Com- mittee and followed accordingly. The animal was inoculated with fresh 2 × 10 4 P. coatneyi–infected erythrocytes/kg (cor- responding to a total number of 1.77 × 10 5 ) obtained from a donor monkey previously infected with a cryopreserved sta- bile. The monkey’s temperature was recorded every day after experimental challenge using a subcutaneous transponder chip (Bio Medic Data Systems, Seaford, DE). Capillary blood samples were obtained every day by ear prick and collected into EDTA-coated capillary tubes. Blood samples were used to determine hemoglobin concentration using a HemoCue photometer (HemoCue, Lake Forest, CA) and to quantify * Address correspondence to Alberto Moreno, Emory Vaccine Cen- ter, Yerkes National Primate Research Center and Division of Infec- tious Diseases, Department of Medicine, Emory University, 954 Gatewood Rd., Atlanta, GA 30329. E-mail: amoreno@rmy. emory.edu Am. J. Trop. Med. Hyg., 76(4), 2007, pp. 648–654 Copyright © 2007 by The American Society of Tropical Medicine and Hygiene 648