Thomas M. Sodeman

Pitting function of the spleen in malaria: Ultrastructural observations

Ultrastructural studies of spleens from monkeys infected with Plasmodium knowlesi suggest that the spleen removes or pits malaria parasites from red cells. This function may explain the presence of nonparasitized spherocytic erythrocytes in the peripheral blood and may in part account for the discrepancy between the excessive hemolysis and the number of parasitized erythrocytes in animals with experimentally induced malaria.

Bacteraemia in asymptomatic human subjects

Summary-The common occurrence of post-tooth extraction bacteraemia provides a convenient model system to evaluate techniques which demonstrate the magnitude of the bacteraemia. The system used continuous anaerobiosis and membrane filter recovery to quantitate bacteraernia. 19 of 22 pre-extraction blood samples and 20 of 22 post-extraction samples from hospitalized patients had one or more colonies per 5 ml of blood. Colonies recovered averaged 7.3 per 5 ml of blood for the pre-extraction samples and 10.7 for the post-extraction samples. 86 per cent of the pre-extraction bloods contained bacteria. 30 of 42 pre-extraction and 32 of 41 post-extraction samples from asymptomatic patients having teeth extracted had a bacteraemia which averaged about 5 colonies per 5ml of blood. Subsequent studies were concerned with the prevalance of detectable bacteraemia. In one series of presumably healthy blood bank donors, blood from 16 of 20 donors was positive for bacteria, with an average recovery of 11 organisms per 5 ml of blood. In a second series, in which multiple samples were tested, 18 of 29 donors were positive with an average recovery of 2 organisms per 5 ml of blood. The taxonomic characteristics of the isolates suggested that they could have originated from the intestine (Streptococcus fuecalis), the skin (Propionibacm%un ucnes and Staphytococcus epidermidis) and the oral cavity (Actinomyces ~iscosus).

Candida Myocarditis Without Valvulitis

Thirty-one patients with systemic candidiasis at postmortem examination were found to have Candida involvement of the myocardium without valvulitis. Retrospective examination of their clinical course demonstrated that a new conduction disturbance was seen in 10, supraventricular arrhythmias in 5,QRS changes mimicking myocardial infarction in 3, and pronounced T wave changes in 13. Hypotension or shock was seen in 13 patients and could not be explained by coexistent bacteremia or blood loss in 8. One patient died suddenly. Of 19 patients with systemic candidiasis without myocardial invasion, 4 had minor T wave changes and one had a supraventricular arrhythmia. Candida invasion of the heart significantly complicates the clinical course in systemic candidiasis and should be suspected when a young person without preexistent heart disease has cultures positive for a Candida organism, a significant arrhythmia, conduction distrubance or other dramatic QRS change. The effect of therapy on Candida invasion of the heart is unknown.

Fine Structure of the Exoerythrocytic Stage of Plasmodium cynomolgi

The light microscopy of primate exoerythrocytic stages (liver stage) of malaria is well described. This report demonstrates the ultrastructure of the 7-day exoerythrocytic stage of Plasmodium cynomolgi in the liver of a rhesus monkey.

Monkey to man transmission of Plasmodium falciparum by Anopheles freeborni mosquitoes.

Infections of Plasmodium falciparum (Malayan IV strain) in the Aotus trivirgatus monkey were shown to be infectious to Anopheles freeborni mosquitoes. Sporozoite positive salivary glands were found 12 to 19 days after feeding. Transmission of the infection to two men was obtained by the bites of infected mosquitoes after extrinsic incubation periods of 14 to 17 days. The prepatent periods in the men were 11 and 12 days. The successful infection of New World monkeys with human malaria was first reported with Plasmodium falciparum in the howler monkey, Alouatta villosa, by Taliaferro and Taliaferro (1934) and Taliaferro and Cannon (1934). More recently, night monkeys, Aotus trivirgatus, titi marmosets, Saguinus geoffroyi, and the squirrel monkey, Saimiri sciureus, have been infected with P. vivax (Young et al. 1966; Porter and Young, 1966; and Deane, et al. 1966). In addition, Aotus trivirgatus monkeys and S. geoffroyi marmosets have been infected with P. falciparum (Geiman and Meagher, 1967; Porter and Young, 1967). Anopheles albimanus mosquitoes infected with P. vivax by feeding on an Aotus trivirgatus monkey transmitted the infection by bite to two human volunteers (Young et al. 1966) and Anopheles freeborni mosquitoes infected with P. falciparum by feeding on this species of monkey transmitted the infection by bite to one human volunteer (Contacos and Collins, 1968). These successful efforts to infect New World monkeys with the human malarias have made it possible to use these hosts for the study of the human malaria parasites. Reported here are the results of mosquito infectivity studies with Aotus trivirgatus monkeys infected with P. falciparum using Anopheles freeborni mosquitoes. MATERIALS AND METHODS The strain of P. falciparum was the Malayan IV which was isolated from a Peace Corps volunteer who contracted the infection while working in the Central Perak area of Peninsular Malaysia (Chin et al. 1966). The parasite is resistant to chloroquine, chlorguanide, pyrimethamine, and mepacrine but yields to 5 days of quinine sulfate at 30 grains per day. Received for publication 2 August 1968. The An. freeborni mosquitoes were the F-l strain originally isolated from Marysville, California and maintained in the laboratory since then (Hardman, 1947). During the infection, thick and thin blood films were made, stained with Giemsa and parasite counts recorded per 100 WBC. Aotus trivirgatus monkeys were obtained commercially. Prior examination indicated that they were free of natural malarial infection. For monkey feeding, mosquitoes were caged in pint ice cream cartons, both ends of which were covered with nylon bobinet. The monkeys were bound to a board, the center of which had been cut out so that when suspended by the four corners, the shaved belly of the monkey could be rested on the top of the mosquito cage. Mosquitoes fed directly through the netting and after feeding were transferred to a constant temperature incubator and held at 25 C. Cellulose pledgets soaked with 5% Karo solution were applied daily. Dissections were started on the 5th day after feeding. For the transmission attempts, mosquitoes were transferred to small plastic tubes and fed individually on a human volunteer. After feeding, mosquitoes were dissected and the salivary glands examined for presence of sporozoites.

Studies of the exoerythrocytic stages of simian malaria. VI. Plasmodium hylobati.

Exoerythrocytic schizonts of Plasmodium hylobati were found in hepatic tissue acquired 7 and 14 days following intravenous inoculation of a gibbon (Hylobates moloch) with sporozoites from Anopheles balabacensis balabacensis. In addition, tissue schizonts were observed in hepatic tissue acquired 7 days after intrahepatic inoculation of an owl monkey (Aotus trivirgatus) with sporozoites also from A. b. balabacensis. While the morphologic features of the exoerythrocytic stages were not sufficiently distinctive, the size difference may be adequate to differentiate this species from other tertian plasmodia of nonhuman primates. This paper is the sixth in a series on the exoerythrocytic (EE) stages of simian malaria (Held and Contacos, 1967; Held et al., 1967a, 1968; Sodeman et al., 1969a, 1969b). The last paper in this series dealt with the EE stage of Plasmodium jefferyi, one of four malaria species described from the gibbon (Warren et al., 1966). The present report describes the EE body of another species of gibbon malaria, P. hylobati, in the gibbon and in the owl monkey. This species of malaria has a tertian periodicity and was initially described by Rodhain (1941) in a Hylobates moloch gibbon from Java. MATERIALS AND METHODS An H. moloch gibbon, harboring a natural infection of P. hylobati, was made available for study by Professor P. C. C. Garnham. The details of the history of this gibbon were described by Collins et al. (1972). Upon arrival, thick blood smears demonstrated a very low-grade parasitemia. Splenectomy (Sodeman et al., 1970) was performed which resulted in a marked elevation of parasites in the peripheral blood. Within 6 days, gametocytes appeared in the peripheral circulation which proved infective to insectary-reared Anopheles balabacensis balabacensis mosquitoes. The method used in the infection and maintenance of the mosquitoes, as well as the details of the sporogonic cycle, are reported elsewhere (Collins et al., loc. cit.). Eight days after splenectomy, the parasite count reached 315,000/mm3, and the gibbon was given a curative dose of chloroquine. Sporozoites were harvested in 10% monkey serum saline from salivary gland preparations of A. b. balabacensis mosquitoes after 11, 12, and 13 days of extrinsic incubation. Sporozoites from 95 Received for publication 18 May 1971. * Present address: University of Michigan Medical Center, Department of Pathology, Ann Arbor, Michigan 48104. pairs of heavily infected glands were inoculated intravenously into the same gibbon that yielded the original infection, 10 days after completion of chloroquine therapy. At the same time, triturated bodies of the same mosquitoes from which sporozoites had been harvested were inoculated intravenously. Sporozoites from 20 pairs of heavily infected glands after 13 days of extrinsic incubation in A. b. balabacensis mosquitoes were inoculated at laparotomy directly into the liver of an owl monkey (Aotus trivirgatus) that was free of malaria, and the site of inoculation was tagged with a stainless steel wire after the technique of Held et al. (1967b). No antibiotic medication was given after the inoculation of sporozoites. Seven and 14 days following inoculation of the gibbon and 7 days following intrahepatic inoculation in the owl monkey, hepatic biopsies were performed. Tissues acquired at the biopsies were fixed in Caroys fluid, embedded in paraffin, and sectioned at 1, 2, 3, and 6 /L. These sections were stained with Giemsa by the technique of Shortt and Cooper (1947) as modified by Eyles (1960). The photomicrographs were made with a Zeiss photomicroscope.