Proteus 0Xi9 , OXK and sera from rats re- covered from haemobartonellosis. Pathogenicity: Infected blood, liver sus- pension, defibrinated laked blood, washed red blood cells, plasma and hemoglobinuric urine may produce infection by the subcu- taneous, intravenous, intraperitoneal or intracardiac routes. Slight, transient or no haemobartonellosis then occurs in adult, non-splenectomized, haemobartonella-free, albino rats; in adult, non-splenectomized, albino rats of carrier stock; or finally in adult, splenectomized rats previously in- fected, during a period lasting 15 weeks to 8 months after infection. Typical haemobar- tonellosis occurs in adult, splenectomized, haemobartonella-free, albino rats and in young, non-splenectomized, haemobarto- nella-free, albino rats weighing 20 to 30 grams at 3 weeks. Latent infections regu- larly become patent following splenectomy and may follow coincident infections with other microorganisms, chemotherapy, in- jections of polonium nitrate or of "anti-rat- spleen" serum. Variable results have been obtained by different investigators with wild mice, guinea pigs, rabbits, hamsters, pigeons and monkeys {"Macacus rhesus" and Macacus sp.). Known to be infectious for wild rats, albino mice, rabbits and for two Palestinian rodents (Spalax typhlops and Meriones tristrami). Negative results have been reported in dogs, kittens, cats, sheep and various birds. Causes a definite and characteristic anemia without cutane- ous eruption. Antibiotic- and chemo-therapy: Penicillin is ineffective; there is true sterilization of latent or recognized infection with organic arsenical compounds; chlortetracycline (au- reomycin) and oxytetracycline (terramycin) are active. Source: Found in the blood of infected albino rats. Habitat: Found in ectoparasites such as the rat louse (Polyplax spinulosus) , the flea {Xenopsylla cheopis) and possibly the bed- bug (Cimex lectularius) . Also found para- sitizing the erythrocytes of susceptible animals. World wide distribution. 2. Haemobartonella microti Tyzzer and Weinman, 1939. (Tyzzer and Weinman, Amer. Jour. Hyg., 30 (B), 1939, 143; also see Weinman, Trans. Amer. Philosoph. Soc, 33 (N.S.), 1944,312.) mi.cro' ti. M.L. mas.n. Microtus a genus of voles; M.L. gen. noun microti of Microtus. In infected animals the morphology re- sembles that of Haemohartonella canis, the organisms occurring as rods, coccoids, filaments, club forms, ring forms and granu- lar masses. In addition to these forms there occur in Giemsa-stained blood films ellips- oids and diamond- or flame-shaped small forms as well as coarse, segmented or un- segmented filaments up to 5 microns in length. The filaments may contain one or more rings or may be composed in part or entirely of diamond-shaped, coccoid or ovoid elements, sometimes arranged in parallel rows. Rods often show intense bipolar staining. Coccoid forms, usually scattered, may occur as aggregates or clumps on the red blood cell, apparently embedded in a faint blue matrix. A pale blue, veil-like substance may cover nearly half of one surface of the red blood cell and show, at its border, typical red- violet -stained rods or filaments in the Giemsa-stained specimens. A bow -shaped arrangement of elements is characteristic. Morphology varies markedly with the kind of host employed. Organisms lie on the sur- faces of the red blood cells. In cultures, organisms are more uniform in morphology. Individual organisms are fine rods, 0.3 by 1.0 to 2.0 microns, sometimes occurring in chains and often in clumps. Small, round forms measuring 0.5 micron in diameter and occasionally round, disc-like structures occur. Cultivation: Growth in Noguchi's semi- solid serum agar two weeks after inoculation with citrated or heparinized blood and in- cubated at 23° C. appears as white, rounded masses measuring up to about 1 mm in the upper 15 mm of the tube. In tissue culture the organism grows in small, rounded, com- pact masses within the cytoplasm of in- fected cells. Indefinite maintenance of the strains isolated on artificial media has not been possible. Pathogenicity: Splenectomized white mice and splenectomized laboratory-reared voles are readily susceptible to infection.
