Day Of Patency Research Articles

External factors and self-regulating mechanisms which may influence the sporulation of oocysts of the rat coccidium, Eimeria nieschulzi

Oocysts of rat coccidium Eimeria nieschulzi were collected daily during the patent period from rats infected with 5000 sporulated oocysts. The discharged occysts were allowed to sporulate under laboratory conditions by using several different techniques and by manipulating the variables associated with these techniques. Parameters examined included: (1) the bottom area of the sporulation container in which the oocysts were kept, (2) the numbers of oocysts/container, (3) the relative quantity of daily fecal debris, (4) the surface area for O 2 exchange, (5) the volume and depth of the oocyst-containing medium (3 % aqueous potassium dichromate), and (6) the day of patency. Factors (2) and (3) seem to be the most important in determining whether or not oocysts will sporulate. In all cases where a low percent sporulation (<80%) was seen, either large numbers of oocysts were packed together or oocysts were associated with much fecal debris, or both. The possible existence of a sporulation inhibiting factor (SIF) and the evolution of such a device as well as the selective value of self-regulating mechanisms in populations of parasites are discussed.

The requirement of thymus competence for both humoral and cell-mediated steps in expulsion of Nippostorngylus brasiliensis from mice.

The worm damaging process (step 1 of Nippostrongylus brasiliensis expulsion from rodents) does not occur in congenitally thymus-deficient (nude) mice as determined by worm morphology, female worm fecundity, and kinetics of worm expulsion upon transfer into normal rats. Expulsion of damaged N. brasiliensis (step 2) does not occur subsequent to transfer of such worms from rats into nude mice. Morphological changes and reduced fecundity appeared in adult worms from normal thymus-bearing mice as early as the first day of patency (day 6 of infection). Thus, the worm damaging process is initiated several days earlier in mice than in rats and may, therefore, account for the reduced longevity of N. brasiliensis in mice compared with rats.

The experimental transmission of Plasmodium malariae to Anopheles labranchiae atroparvus.

The Vs strain of P. malariae proved very infective for laboratory-bred A. l. atroparvus; of 31 batches fed on 11 gametocyte carriers, 24 (77·4%) became infective. Oöcysts were first seen 5 days after the blood meal; development was slow, 5–14 days, after which they measured 6–64μ. The greatest number of oöcysts per gut was 60 (average 24) in one batch; the average for all batches was 3·5. Sporozoites first appeared in the salivary glands on day 15; they measured 12–14μ in length in fresh preparations, and 10·5μ in stained preparations. Sporogony developed in 15–20 days, in mosquitoes kept at 19°–30°C. From 1 to 98·6% of A. l. atroparvus in the various batches became infected, but not in accordance with the density of male gametocytes. The ability of male gametocytes to originate sporogony in A. l. atroparvus extends from 8 to 404 days of patency. The highest degree of infectivity was 98·6% of one batch of mosquitoes, fed during the second week of patency. Success in infecting mosquitoes depends upon the quality of the gametocytes, the susceptibility of the mosquitoes, and the number of mosquitoes in each batch used.

Biology of the Malaysian Strain of Plasmodium juxtanucleare Versiani and Gomes, 1941. III. Life Cycle of the Erythrocytic Parasite in the Avian Host

Some aspects of the life history of the Malaysian strain of Plasmodium juxtanucleare are presented. The periodicity of the parasite is believed to be an asynchronous, quotidian parasitemia with a long period of chronicity. Mature parasites are more common in visceral blood than in the peripheral circulation, indicating deep circulation schizogony. The parasite normally invades mature erythrocytes, with multiple infection of a cell uncommon except in instances of high parasitemia. The gametocytes are only slightly infective to mosquitoes during the first 30 days of patency, but subsequently become much more infective. Chronic infections remain highly infective to mosquitoes for as long as 198 days. The parasite could not be transmitted to canaries or young ducks. In the first paper of this series (Bennett and Warren, 1966) the asexual stages of the Malaysian strain of Plasmodium juxtanucleare were described, and in the second paper (Bennett et al., 1966) the development of the same parasite in the mosquito host was presented. The biology of P. juxtanucleare has been investigated to some extent by Al-Dabagh (1961) working with the Brazilian strain and by Dhanapala (1962) with the Ceylonese strain. This report is concerned with the biology of the Malaysian strain in the avian host with particular reference to periodicity of the asexual parasites in the peripheral blood, host cell preference, and infectivity of the gametocytes. In addition, this strain is compared with other known strains of the parasite and with other members of the subgenus Novyella. MATERIALS AND METHODS The parasite was maintained in the laboratory in young, hatchery-bred chickens by a combination of parasitized blood and sporozoite transfers. All birds were maintained in mosquito-proof cages. Subcutaneous, intravenous, and intraperitoneal routes were used for inoculations. Heparin was used as the anticoagulant for all parasitized blood transfers. Routine blood smears were made from the brachial vein at 0800 hr and stained with Giemsa stain at pH 7.2. Incisions through the body wall above the liver on anesthetized birds provided access to the liver for the hepatic smears. The incisions were closed with adhesive plaster and the birds treated with penicillin. The birds were then Received for publication 1 March 1966. * Present address: Ontario Research Foundation, 43 Queen's Park, Toronto 5, Ontario, Canada. anesthetized with ether, the incision opened, and smears made from the cut surface of the liver at desired intervals. Sporozoites for both routine and experimental transfers were obtained by dissecting the salivary glands from infected mosquitoes into Haye's saline. The glands were then crushed and the sporozoites collected in a mixture of 90% physiological saline10% serum (monkey or rabbit).

Transmission of a New Strain of Plasmodium cynomolgi to Man

Transmission of a New Strain of Plasmodium cynomolgi to Man

Influence of Pregnancy and Lactation on Migration of the Larvae of Toxocara canis in Mice

Ehrenford (1957) reported a marked and increasing resistance to infection with Toxocara canis in female dogs 6 to 36 months of age. Schacher (1957) found no growth of larvae beyond the infective stage in the tissues or intestine of non-pregnant dogs, and many larvae were found encapsulated in the liver, kidney, lung, heart, and carcass. On the other hand, Fiilleborn (1921), Augustine (1927), Yutuc (1947), Douglas and Baker (1959), and Webster (1958) reported the development of T. canis to the adult stage in the intestine of fairly old dogs during the lactation period. Douglas and Baker (1959) kept 5 female dogs free of exposure to T. canis for 241 to 358 days after the initial infection and observed the appearance of eggs in the feces of all of them within 25 to 46 days of whelping, and in the feces of the pups in every litter 23 to 40 days after birth. In the old dogs the infections were lost spontaneously after 9 to 108 days of patency. These findings suggested that pregnancy and lactation influence the migratory behavior and development of T. canis larvae in the dog. The present study was undertaken to determine whether gestation and lactation have any influence on the behavior of T. canis larvae in mice.

A Note on the Apparent Antagonism of a Bacterial Intoxication to a Plasmodial Infection 1

SummaryA colored male patient with meningoencephalitic syphilis was inoculated with Plasmodium falciparum for malariatherapy. Although the inoculation was successful, the malaria infection was atypical, chiefly because the parasites did not attain densities proportional to the elevations of temperature experienced. Although the plasmodial infection was subsiding spontaneously, it was therapeutically terminated on the 14th day of patency without interruption of the fever. It was thereupon discovered that the patient had a gas bacillus infection in the perineal region, which was finally overcome by the massive administration of pencillin, sulfadiazine and antitoxin. Recovery from the gas bacillus infection was complete, although healing of the area from which necrotic tissue had sloughed required several months, and was associated with marked improvement in the syphilitic infection. The plasmodicidal therapy administered could not have been sufficient to have aborted the malaria infection in the manner observed. It appears likely that the gas bacillus infection was active for some days prior to its discovery, and that the soluble exotoxin it produced may have adversely affected the plasmodia.