Aotus lemurinus griseimembra monkeys: a suitable model for Plasmodium vivax sporozoite infection

This study describes a successful Plasmodium vivax sporozoite infection in Aotus lemurinus griseimembra. Twenty-eight naive or previously infected monkeys, either splenectomized or spleen intact, were inoculated intravenously or subcutaneously with Plasmodium vivax sporozoites of the Salvador I strain or with two wild isolates (VCC-4 and VCC-5; Vivax-Cali-Colombia). The monkeys were successfully infected regardless of the parasite strain, spleen presence, or inoculation route and showed prepatent periods that ranged from 16 to 89 days. Only one monkey inoculated intravenously failed to develop parasitemia. Since immune protection against malaria pre-erythrocytic forms is mediated by both helper and cytolytic T cells that may home in the spleen and P. vivax cultures are not yet available; the use of spleen-intact A. lemurinus griseimembra, susceptible to both adapted and non-adapted strains of P. vivax sporozoites, is a valuable model for evaluation of pre-erythrocytic vaccine candidates.

Entamoeba histolytica infections in captive primates

A group based survey on the presence of Entamoeba histolytica and Entamoeba dispar using real-time PCR among 20 species of captive non-human primates was performed after diagnosis of E. histolytica dysentery in a spider monkey ( Ateles belzebuth hybridus). E. histolytica DNA was detected in three species of New World primates and in three species of Old World primates. In five of six E. histolytica isolates, it was possible to amplify the SREHP gene. They all revealed the same pattern after AluI digestion, indicating a common source of infection. E. dispar DNA was detected in two species of New World monkeys and three species of Old World monkeys. The results demonstrate that E. histolytica is capable of causing symptomatic and non-symptomatic infections in Old World and New World non-human primates. To our knowledge, this is the first report of E. histolytica sensu stricto in non-human primates after the redescription separating it from E. dispar in 1993.

Transmission dynamics of Cryptosporidium in primates and herbivores at the Barcelona zoo: a long-term study

Factors influencing the transmission of Cryptosporidium in primates and herbivores housed at the Barcelona zoo have been analyzed. The relationship between continuous and discontinuous oocyst shedding, both animal housing conditions and abiotic factors (seasonality, humidity, temperature) was examined to explain the epizootiology of the protozoan. Thirty six fecal samples from each of 11 primates (Pongidae, Cebidae, Cercopithecidae and Lemuridae) and 22 herbivores (Elephantidae, Camelidae, Cervidae, Giraffidae and Bovidae) were examined over the period of 1 year. The parasite transmission was based on the chronic infection status of some animals serving as a source of successive reinfection for other animals. The environmental temperature and humidity (seasonality), the physical features of the facilities, the vicinity of the animals and the physiological status induced by captivity contributed to transmission. The long-term character of this study was essential for obtaining these results and interpreting the complex relationships.

Adaptation of a strain of Plasmodium vivax from India to New World monkeys, chimpanzees, and anopheline mosquitoes

A strain of Plasmodium vivax from India was adapted to develop in splenectomized Saimiri boliviensis, Aotus lemurinus griseimembra, A vociferans, A. nancymai, A. azarae boliviensis, hybrid Aotus monkeys, and splenectomized chimpanzees. Infections were induced via the inoculation of sporozoites dissected from the salivary glands of Anopheles stephensi and An. dirus mosquitoes to 12 Aotus and 8 Saimiri monkeys; transmission via the bites of infected An. stephensi was made to 1 Aotus monkey and 1 chimpanzee. The intravenous passage of infected erythrocytes was made to 9 Aotus monkeys and 4 chimpanzees. Gametocytes in 13 Aotus monkeys and 4 chimpanzees were infectious to mosquitoes. Infection rates were markedly higher in mosquitoes fed on chimpanzees. PCR studies on 10 monkeys injected with sporozoites revealed the presence of parasites before their detection by microscopic examination. The India VII strain of P. vivax develops in Aotus and Saimiri monkeys and chimpanzees following the injection of parasitized erythrocytes, or sporozoites, or both. The transmission rate via sporozoites to New World monkeys of approximately 50% may be too low for the testing of sporozoite vaccines or drugs directed against the exoerythrocytic stages. However, the strain is highly infectious to commonly available laboratory-maintained anopheline mosquitoes. Mosquito infection is especially high when feedings are made with gametocytes from splenectomized chimpanzees.

Trypanosoma cruzi infection in Leontopithecus rosalia at the Reserva Biológica de Poco das Antas, Rio de Janeiro, Brazil

Wild golden lion tamarins (Leontopithecus rosalia) - endangered primates that are native to the Brazilian Atlantic coastal forest - were surveyed for the presence of Trypanosoma cruzi with the use of Giemsa-stained blood smears, hemocultures and an indirect immunofluorescence assay (IFAT). Positive IFAT with titers ranging from 1:20 to 1:1280 were observed in 52% of the 118 wild tamarins examined and the parasite was isolated from 38 tamarins. No patent parasitemia was observed among the tamarins from which T. cruzi was isolated. Serum conversion and positive hemoculture was observed for three animals that had yielded negative results some months earlier, which indicates that T. cruzi is actively transmitted among tamarins. In contrast to observations with other sylvatic isolates, those from the tamarins were significantly more virulent and most of them produced mortality in experimentally infected Swiss mice. Some variation in the kDNA restriction profiles among the isolates was observed. Electrophoresis with GPI, G6PDH, IDH, MDH and ME enzymes showed a Z2 profile.

Monkeys of the rainforest in French Guiana are natural reservoirs for P. brasilianum/P. malariae malaria

Monkey blood samples were collected from 214 monkeys relocated as part of the wildlife rescue organized in French Guiana during the filling of the Petit Saut Dam on the Sinnamary River. These samples were tested for malaria parasites by microscopy of thick blood filsm and by nested PCR for small subunit rRNA genes (SSUrRNA). Parasitic blood forms similar to Plasmodium brasilianum were detected in 4 monkey species: Alouatta seniculus macconnelli, Saguinus midas midas, Pithecia pithecia and Ateles paniscus paniscus, with the highest prevalence in Alouatta monkeys. PCR was more sensitive than the conventional method for detecting low-grade parasitaemia in positive monkeys. The examination of blood films indicated that 5.6% of the animals carried parasites whereas the nested PCR for ribosomal DNA indicated a prevalence of 11.3%. The P. brasilianum SSUrRNA gene sequence was analysed and aligned with those from P. malariae, P. falciparum and P. vivax. This suggested that P. brasilianum and P. malariae are very closely related. Similar results were obtained from analysis of the sequences in P. malariae and P. brasilianum isolates of a polymorphic gene fragment analogous to the merozoite surface protein-1 (MSP-1) gene of P. falciparum. The P. brasilianum/P. malariae sequences were more similar to those of P. vivax than to those of P. falciparum, at least in the gene region examined. The high degree of DNA homology in the sequences of the SSUrRNA and msp1-like genes is consistent with other characterizations demonstrating a taxonomic relationship between P. brasilianum and P. malariae species. Our results provide further evidence that P. brasilianum and P. malariae are virtually identical and should probably be considered to be a single malaria species. This raises the question as to whether monkeys living in the rainforest are natural reservoirs for both simian and human malaria. These results have implications for the interpretation of the current epidemiological situation in French Guiana.

Presumptive dirofilariasis in a pale-headed saki monkey (Pithecia pithecia)

A 6-yr-old male pale-headed saki monkey (Pithecia pithecia), born at the Dallas Zoo, reentered the collection in 1994 after it was housed for 4 yr in Rhode Island and 2 yr in Florida. The monkey tested negative for both Dirofilaria immitis microfilariae and D. immitis adult antigens (via commercially available tests) upon return. However, it tested positive for adult antigens 1 yr later, and additional testing, including ultrasonography, suggested a diagnosis of aberrant dirofilariasis. Relevant evidence of previous microfilaremia in pale-headed saki monkeys at the Dallas Zoo is reviewed. Dirofilaria immitis infection should be included in the differential diagnosis list for any nonhuman primate with cardiopulmonary disease wherever the parasite is enzootic.

[Parasitological evidence on the phylogeny of hominids and cebids]

A systematic revision of the ectoparasites (lice) of the hominids and ceboids supports the Trogloditian hypothesis, according to which the genus Homo is the sister of Pan, and the genus Gorilla the sister group of both. The phylogenetic analysis of this matrix derived from the study of primate lice shows an C.I. of 0.71 for the Trogloditian hypothesis including the ceboids in the analysis.

Simian malaria at two sites in the Brazilian Amazon. I--The infection rates of Plasmodium brasilianum in non-human primates

The parasite that causes simian malaria in the Brazilian Amazon, Plasmodium brasilianum, is infective to man. In this region, where humans live within and in close proximity to the forest, it was suspected that this parasite could be the cause of a zoonosis. A study was performed in the areas surrounding two hydroelectric plants in the Amazon, Balbina and Samuel, aiming at determining the zoonotic potential of this parasite. P. brasilianum was detected in, respectively, 15.8% and 9.9% of 126 and 252 primates belonging to seven and eight species examined from Balbina and Samuel. The highest malaria infection rates were found among the red-howler monkey Alouatta seniculus straminea (32.3%), the bearded-saki Chiropotes satanas chiropotes (50%) and the spider-monkey Ateles paniscus paniscus (2[1+]) from Balbina and in the squirrel-monkey Saimiri ustus (21%) and the black-faced-spider-monkey Ateles paniscus chamek (28.6%) from Samuel.

Simian malaria in Brazil

In Brazil simian malaria is widely spread, being frequent in the Amazon region (10% of primates infected) and even more in the forested coastal mountains of the Southeastern and Southern regions (35% and 18% infected, respectively), but absent in the semi-arid Northeast. Only two species of plasmodia have been found: the quartan-like Plasmodium brasilianum and the tertian-like P. simium, but the possible presence of other species is not excluded. P. brasilianum is found in all enzootic foci, but P. simium was detected only on the coast of the Southeastern and Southern regions, between paralles 20 degrees S and 30 degrees S. Nearly all hosts are monkeys (family Cebidae, 28 species harbouring plasmodia out of 46 examined), and very rarely marmosets or tamarins (family Callitrichidae, 1 especies out of 16). P. brasilianum was present in all infected species, P. simium in only two. The natural vector in the Southeastern and Southern regions was found to be Anopheles cruzi, but has not been conclusively identified in the Amazon. One natural, accidental human infection due to P. simium was observed. There is no evidence of the relation of simian to human malaria in the Southeastern and Southern regions, where human malaria was eradicated in spite of the high rates of monkeys infected, but in the Amazon recent serological studies by other workers, revealing high positivity for P. brasilianum/P. malariae antibodies in local indians, would suggest that among them malaria might possibly be regarded as a zoonosis.

Intestinal capillariasis in New World monkeys

Two cases of intestinal capillariasis have been identified at necropsy in a squirrel monkey and a capuchin monkey born and raised in captivity. The parasites are described as far as possible from the histopathological slides or intestinal contents, and their relationship to other intestinal capillarids, especially those of primates, is discussed.

Infection of Aotus vociferans monkeys with different strains of Plasmodium falciparum

Twenty-one splenectomized Aotus vociferans monkeys were infected with the different strains/clones of Plasmodium falciparum. Maximum parasitemia ranged from 1,302 to 1,460,000 parasites per mm3. Only the Santa Lucia strain was shown to produce gametocytes for extended periods. Gametocytes produced during the primary episode of parasitemia were highly infective to Anopheles freeborni mosquitoes. Gametocytes produced during recrudescence were not infective to mosquitoes feeding directly on the animals. This lack of mosquito infection during recrudescence periods suggests the presence of transmission-blocking immunity, which may be important in understanding the control of malaria through immunologic initiatives.

Invasive amebiasis in a spider monkey (Ateles geoffroyi). Case report and a short review of the literature of amebiasis in non-human primates

A spider monkey (Ateles geoffroyi) studied at the San Juan de Aragon Zoo died with symptoms of amoebic dysentery verified by coprologic investigation of the parasite, his female partner was cured with conventional antiamoebic treatment. At autopsy widespread ulcerations in the colon and multiple liver abscesses were found, containing trophozoites of Entamoeba histolytica. Both lesions were identical to those observed in human amoebiasis. A short review of the literature in nonhuman primates infections points out that the so-called spontaneous amoebiasis seen in colonies of captive monkeys, and transmission to their newborns within the same species of monkeys, have been in contact with humans. It is proposed that amoebiasis in monkeys should be considered as an excellent model for experimental studies on amoebiasis because other phylogenetically distant species have shown different pathology or are resistant to the infection. Also, it should raise concern that monkeys may become carriers of cysts and trophozoites of virulent strains of E. histolytica. Entamoeba histolytica DNA hybridization techniques should be considered for comparing genomic similarities with other protozoa, including the genera Amoeba to establish its pattern of evolution.

Anatomical distribution of developing trophozoites and schizonts of Plasmodium vivax in Aotus lemurinus lemurinus and Saimiri sciureus

Organ distribution of developing trophozoite- and schizont-infected erythrocytes of Plasmodium vivax and night monkeys, Aotus lemurinus lemurinus, and squirrel monkeys, Saimiri sciureus, was determined. The primary site for the infection in both species was the splenic vasculature. Secondary organ involvement differed between hosts although some overlapping did occur.

Eosinophilic meningoencephalitis due to Angiostrongylus cantonensis as the cause of death in captive non-human primates

Fatal eosinophilic meningoencephalitis due to Angiostrongylus cantonensis is reported in captive non-human primates. A howler monkey (Alouatta caraya) at the Audubon Park and Zoological Gardens, New Orleans, LA, died 21 days after initial clinical symptoms. A white-handed gibbon (Hylobates lar) died at the Ardastra Gardens and Zoo, Nassau, Bahamas, 17 days after onset of symptoms. Both had access to free-ranging gastropods within the zoos. These are the first reported cases of natural infection by A. cantonensis in non-human primates in the western hemisphere.

Adherence and surface properties of Tritrichomonas mobilensis, an intestinal parasite of the squirrel monkey

Adherence properties of the potentially enteropathogenic Tritrichomonas mobilensis were studied in vitro. Axenically cultivated trichomonads readily attached to isolated intestinal epithelial cells and mucus of the squirrel monkey. The kinetics and nature of T. mobilensis cytadherence were microscopically evaluated in cell-suspension assay using Chinese hamster ovary (CHO) cells and in microplate hemagglutination assay with human erythrocytes. Adherence of the parasites to target cells was concentration- and time-dependent; it was inhibited by sialic acid (N-acetylneuraminic or N-glycolylneuraminic acid) and sialyllactose. Neither trypsinization of the flagellates nor their exposure to low temperature (4 degrees C) affected their cytadherence capacities. The data indicate the presence of adhesin(s) with lectin properties on T. mobilensis. Agglutination of live protozoa by animal and plant lectins with various carbohydrate-binding specificities as well as the occurrence of an electron-dense cell coat on plasma membrane suggest marked glycosylation of the parasite surface.

Serologic evidence of Encephalitozoon cuniculi infection in a colony of squirrel monkeys (Saimiri sciureus)

Five hundred seventeen serum samples obtained during 3 years from a collection of 250 squirrel monkeys were examined by indirect immunofluorescence and dot-ELISA for antibodies to Encephalitozoon cuniculi. One hundred seventy-nine monkeys were positive at least once and fifty six monkeys were positive three or more times. Older animals were more likely to be positive than young animals, but the proportion of serologically positive monkeys did not change appreciably over the 3 years. As judged by the serological evidence, infection with E. cuniculi is distributed widely in this collection of squirrel monkeys.

The Uganda I/CDC strain of Plasmodium malariae in Saimiri sciureus boliviensis

The Uganda I/CDC strain of Plasmodium malariae, initially adapted to monkeys of the genus Aotus, was studied in splenectomized Saimiri sciureus boliviensis. Mean maximum parasitemia ranged from 248 to 22,134/mm3. Only 1 mosquito was infected of 2,238 examined. After the parasite was adapted to this host, infections were characterized by periods of detectable parasitemia extending up to 269 days and by sustained periods when parasite counts were greater than 1,000/mm3. After 4 linear passages, the developmental time required before the primary peak parasite count was approximately 2 mo.

Cardiomyopathy in Cebus apella monkeys experimentally infected with Trypanosoma cruzi

Twenty four Cebus apella monkeys were studied as a biological model for the cardiac chronic form of Chagas' disease. Twelve were inoculated with Trypanosoma cruzi trypomastigotes, seven with the Brazilian Y strain and five with the Argentinian RA strain. Twelve monkeys were uninfected controls. The following parameters were studied: body weight, body temperature, direct parasitemia, xenodiagnosis, specific antibodies by IFA, clinical chemistry, hematology, ECG and chest X-ray. Three monkeys infected with Y strain were sacrificed at 4 months and 4 monkeys at 12 months after inoculation. Monkeys inoculated with RA strain were sacrificed at 48 months. Direct parasitemia was positive within a week after inoculation in all monkeys. Xenodiagnosis was positive until 49.0 +/- 3.0 and 79.0 +/- 6.0 weeks p.i. for Y and RA strains, respectively. In all inoculated monkeys an increase in antibody titers was detected within 3 weeks after inoculation. In all monkeys inoculated with the Y strain and 3/5 with the RA strain abnormal ECGs were observed within 1 or 2 weeks p.i., becoming more severe in the chronic phase. Y strain inoculated monkeys sacrificed at 4 months presented only a slight concentric hypertrophy of the heart left ventricle. Those sacrificed at 12 months had concentric left ventricle hypertrophy and 3/4 had an aneurism of the apex. Four out of 5 RA strain inoculated monkeys had an enlarged, flaccid heart; 3/5 aneurism of the apex and 2/5 concentric hypertrophy of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal trichomonads (Tritrichomonas mobilensis) in the natural host Saimiri sciureus and Saimiri boliviensis

A retrospective study of cecal and colonic tissues from 28 squirrel monkeys (Saimiri sciureus and Saimiri boliviensis) demonstrated enteric trichomonads within luminal crypts. Twenty-one of 28 (75%) had trichomonads in the mucosal epithelium either in cup-like depressions or intraepithelial vacuoles. Organisms were also beneath the superficial luminal mucosal epithelium and between the basement membrane and crypt epithelial cells. Immunoperoxidase staining also identified organisms within the lamina propria and submucosa. Additional histologic changes included mucosal ulceration, multifocal cryptitis, and focal epithelial necrosis. Most areas containing trichomonads did not have an associated inflammatory response.

The Uganda I/CDC strain of Plasmodium malariae in Aotus lemurinus griseimembra monkeys

Two lines of the Uganda I/CDC strain of Plasmodium malariae were studied in splenectomized Aotus lemurinus griseimembra monkeys. A line initially adapted to these monkeys from an infected chimpanzee failed to produce high-level parasite counts or mosquito infection in 13 of this type of monkey during 16 linear passages. Another line, originally adapted from the chimpanzee to Aotus azarae boliviensis, after 7 linear passages in 3 different types of Aotus was then passaged to 14 splenectomized A. lemurinus griseimembra. Geometric mean maximum parasitemia in these monkeys was 18,400/mm3. Mosquito infections were readily obtained during the period just after the parasite count rose above 1,000/mm3. Anopheles freeborni, An. stephensi, An. dirus, and 2 strains of An. gambiae supported the development of the parasite to the presence of sporozoites in the salivary glands. Two attempts to transmit the strain to other splenectomized A. lemurinus griseimembra by sporozoite inoculation were unsuccessful.

Invasive amebiasis in naturally infected New World and Old World monkeys with and without clinical disease

Histopathological preparations of cecum and colon from monkeys naturally infected with invasive Entamoeba histolytica were examined to determine the distribution of amebae in the tissues and the types of lesions, if any, associated with them. Infections were studied in 3 New World species (10 Callicebus moloch, 1 C. torquatus, and 2 Aotus trivirgatus) and 3 Old World species (8 Macaca mulatta, 6 Erythrocebus patas, and 1 Cercopithecus aethiops). Amebiasis was recorded as the principal or a contributing cause of death of all of the 13 New World monkeys and in 6 of the 15 Old World monkeys; amebiasis was detected in the rest of the monkeys only after tissues were re-examined specifically for amebae. Amebae causing no apparent damage were found in the lamina propriae, mainly at the muscularis mucosae. Most frequent were colonies or aggregates of amebae in the crypts between the epithelium and basement membrane, causing either no evident necrosis or changes ranging from necrosis and disarrangement of adjacent cells to complete destruction of the epithelium and reduction of the cells to pyknotic bodies. A lesion interpreted as possibly characteristic of carrier-state invasive amebiasis was destruction of the epithelium in patches of mucosal crypts, not leading to ulceration. Uncommon but present in both New and Old World monkeys were typical areas of surface erosion and classical flask-shaped ulcers. The observations show that in some species of Old World monkeys amebiasis can be invasive without causing clinical disease.

Infection of Peruvian Aotus nancymai monkeys with different strains of Plasmodium falciparum, P. vivax, and P. malariae

Aotus nancymai (karyotype I) monkeys from Peru were studied for their susceptibility to infection with Plasmodium falciparum, P. vivax, and P. malariae. Three strains of P. falciparum (Santa Lucia from El Salvador, Indochina I/CDC from Thailand, and Uganda Palo Alto) were inoculated into 38 monkeys. The results indicated that this species of Aotus monkey is highly susceptible to infection. The Uganda Palo Alto and the Santa Lucia strain parasites appear to be the most useful for immunologic and chemotherapeutic studies. Five strains of P. vivax (Chesson, ONG, Vietnam Palo Alto, Salvador I, and Honduran I/CDC) were inoculated into 28 monkeys. The Vietnam Palo Alto strain produced the highest level parasitemias ranging from 23,800 to 157,000/mm3. Mosquito infections were obtained with the ONG, Chesson, and Salvador I strains. Two out of 6 attempts to transmit P. vivax via sporozoite inoculation to splenectomized monkeys were successful with prepatent periods of 39 and 57 days. Five monkeys were infected with the Uganda I/CDC strain of P. malariae. Maximum parasitemias ranged from 10 to 5,390/mm3.

Transmission of the OS strain of Plasmodium inui to Saimiri sciureus boliviensis and Aotus azarae boliviensis monkeys by Anopheles dirus mosquitoes

Eight Saimiri and 7 Aotus monkeys were exposed to infection with the OS strain of Plasmodium inui via the bites of from 2 to 7 Anopheles dirus mosquitoes. All Saimiri monkeys developed high-level infections of from 152,000 to 500,000/mm3 after prepatent periods of from 14 to 17 days. Only 1 Aotus monkey developed a patent infection after a period of 28 days. Feeding on these animals failed to result in infection of An. dirus mosquitoes.

Acute Chagas' disease in non-human primates. 1. Chronology of clinical events, clinical chemistry, ECG, radiology, parasitemia, and immunological parameters in the Cebus apella monkey

Forty Cebus apella monkeys free from Chagas' disease were subcutaneously infected with 3 x 10(5) trypomastigotes of the Ypsilon strain of T. cruzi and followed-up for 6 months. Seventeen monkeys were controls. Body weight, temperature, direct parasitemia (DP), IgM and IgG were determined weekly. Hematology was performed weekly up to day 40 p.i. and monthly thereafter. Clinical chemistry was performed every two weeks up to day 33 p.i. and monthly thereafter. ECG was performed weekly up to day 47 p.i. and at 2,3, and 6 months p.i. Chest X-ray was done at 45 days, 4 and 6 months p.i. Xenodiagnosis was only performed after two negative DP. All infected monkeys developed fever, beginning 6.0 +/- 0.6 day p.i. and lasting 21.9 +/- 6.7 days, and lost 14% of their body weight the first month, 11% the third month and 7% the 6th month. DP was already detected 4.4 +/- 0.29 days after infection and it was detectable in all monkeys up to 96.0 +/- 6.9 days p.i. Cyclical peaks of parasitemia were observed throughout the study. IgM and IgG titers which permitted a diagnosis of T. cruzi infection occurred at 33.0 +/- 2.9 days p.i., respectively. Fifty-seven percent of infected monkeys presented ECG alterations one week after inoculation reaching a maximum of 86% at the third week. A normocytic, normochromic anemia was observed in all monkeys being significantly (p less than 0.02) more severe in the infected animals. No effects of T. cruzi on the clinical chemistry were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term protection of squirrel monkeys (Saimiri sciureus) against Plasmodium falciparum challenge inoculations after various time intervals

When used as an experimental host for Plasmodium falciparum, the squirrel monkey Saimiri sciureus, intact or splenectomized, develops a significant, long-lasting, protective immunity against the blood stages of this parasite. In the present study, this length of protection after a single initial infection was determined by test infections carried out at varying intervals of time in 26 splenectomized animals. An initial period of about 7 months was observed, which was characterized by a marked resistance to trial reinfestations by a homologous as well as a heterologous strain. A second period was observed during which the primates became sensitive to the parasite in varying degrees. These observations single out the squirrel monkey in comparison with other experimental hosts tested under similar conditions and underline the value of research on antimalarial vaccinations, because when confronted with parasite antigens, the organism can produce the immunological response necessary to control a test infection.

Characterization by anti-Ig monoclonal antibodies of protective and non-protective antibodies against asexual forms of Plasmodium falciparum in the Saimiri monkey

Four monoclonal antibodies (mAb) which recognize distinct epitopes on Saimiri immunoglobulins were successfully used to characterize the protective and non-protective antibodies developed by this experimental host in response to infection by the human malaria parasite Plasmodium falciparum. Two of these mAb, 3F11/G10 and 3E4/H8, were IgG-specific and directed against conformationally conserved epitopes on the intact molecule. mAb 3A2/G6 and 4G3/B5 were specific for epitopes on two distinct L chain types of all Ig. Radioimmunoassay and immunoblots indicated that L-chains defined by 3A2/G6 were present in IgG molecules of type 3F11/G10, while L chains defined by 4G3/B5 were associated with IgG of type 3E4/H8. The use of these four mAb as immunoadsorbents allowed the purification of two IgG and two Ig populations. When assayed in vivo by passive transfer experiments in recipient monkeys previously infected by P. falciparum, protection could be associated with the IgG or Ig populations of type 3F11/G10-3A2/G6. In contrast, recipient animals which received the IgG type 3E4/H8 or Ig type 4G3/B5 presented rapidly evolving parasitemia similar to that in animals which received non-immune IgG or protective immune sera depleted of the above Ig or IgG fractions. The identification of protective and non-protective Ig populations will help in the evaluation of vaccine candidates against P. falciparum.

Chesson strain Plasmodium vivax in Saimiri sciureus boliviensis monkeys

Nine Saimiri sciureus boliviensis monkeys were inoculated with sporozoites of Plasmodium vivax (Chesson strain) dissected from Anopheles stephensi mosquitoes infected by feeding on blood from infected chimpanzees. The animals were splenectomized 7 days after inoculation. Seven animals developed infections with prepatent periods ranging from 12 to 43 days (mean of 19.6 days). Parasitemias were low during the first 50 days. Maximum parasitemias in 5 animals in which the strain adapted ranged from 10,000 to 46,800 per mm3. Anopheles freeborni mosquitoes were infected by feeding on 4 of the monkeys.

Adaptation of the Panama II strain of Plasmodium falciparum to Panamanian owl monkeys

The Panama II strain of Plasmodium falciparum, acquired at the second passage level in splenectomized Colombian owl monkeys, was adapted to owl monkeys of Panamanian origin. Patent infections were induced in 22 of 27 unaltered and 20 of 21 splenectomized recipients during 19 serial passages. The infections were significantly more virulent in splenectomized than normal Panamanian owl monkeys, however recrudescences in seven normal monkeys achieved peak parasitemias 48 times greater than in the primary attack. These results describe the first reproducible infections of indigenous falciparum malaria in Panamanian owl monkeys.

Pathologic changes associated with fatal Plasmodium falciparum infection in the Bolivian squirrel monkey (Saimiri sciureus boliviensis)

Fatal cases of experimental Plasmodium falciparum (Indochina I) in Bolivian squirrel monkeys (Saimiri sciureus boliviensis) were examined by histologic and ultrastructural methods. Gross lesions were characterized by hepatosplenomegaly and interstitial pulmonary changes. Histologically, there was marked diffuse reticuloendothelial hyperplasia, pulmonary alveolar septal thickening, mesangioproliferative glomerulonephropathy, sequestration of parasitized erythrocytes in deep vascular beds, degenerative parenchymal changes in the liver and myocardium, and in one case retinal and cerebral hemorrhage. These data indicate that the Bolivian squirrel monkey is a good model for studying pathologic changes associated with human falciparum malaria.

Infection of Aotus vociferans (karyotype V) monkeys with different strains of Plasmodium vivax

Twenty splenectomized Aotus vociferans (karyotype V) monkeys were infected with strains of Plasmodium vivax from New Guinea, North Korea, Indonesia, El Salvador, and Honduras. Peak parasite densities ranged from 4,840 to 75,500 per mm3. Gametocytes infective to different species of mosquitoes were produced with all strains of P. vivax studied. Two transmissions of the Chesson strain of P. vivax were made by the intravenous inoculation of dissected sporozoites from An. dirus mosquitoes. Prepatent periods were 16 days.

In vitro and in vivo adaptation of the Geneve/SGE-1 strain of Plasmodium falciparum to growth in a squirrel monkey (Saimiri sciureus) model

Human erythrocytic culture-adapted parasites of the Geneve/SGE-1 strain of Plasmodium falciparum were successfully adapted to grow in an in vitro culture system containing squirrel monkey erythrocytes and serum. These monkey culture-adapted organisms were then used to produce a patent infection in a splenectomized squirrel monkey. Fresh infected blood from this animal was introduced into another splenectomized monkey and was subsequently serially passed through seven intact squirrel monkeys. High level parasitemias (greater than 10%) were obtained in the animals from the last two passes following inoculation of moderate numbers of parasites. It is anticipated that this squirrel monkey-adapted Geneve/SGE-1 strain of P. falciparum will continue to produce high level parasitemias in intact Bolivian Saimiri, and consequently will be suitable for challenge of these monkeys.

[A 5th filaria of the genus Dipetalonema, parasite of South American monkeys]

Description of D. freitasi n. sp., a parasite of Cebus capucinus: this species, close to D. caudispina, is distinguished by the slightly more complex structure of the vagina and right spicule, the lack of area rugosa on the tail and by the shorter microfilaria. Additional morphological data on the male of D. robini Petit et al., 1985 are given. A comparative table of 4 principal evolutive characters of the genus Dipetalonema (vagina, left and right spicules, epithelio-muscular body wall) is given. D. caudispina and D. freitasi n. sp. represent a small primitive group opposed to the more evolved one made up of D. robini, D. gracile and D. graciliformis.

Experimental visceral leishmaniasis in the owl monkey

Visceral leishmaniasis developed in eight owl monkeys (Aotus trivirgatus) after intravenous inoculation with a Khartoum strain (WR378) of Leishmania donovani. Six monkeys died within 93 days, and two monkeys recovered from the disease. Clinically, signs were weight loss, anemia, and hepatosplenomegaly. Hematologic findings included anemia, granulocytopenia, thrombocytopenia, and lymphocytosis. Analysis of serum or plasma revealed hyperbilirubinemia, azotemia, hyperglobulinemia, hypoalbuminemia, and altered hemostasis. All monkeys developed positive antibody titers to promastigotes of L. donovani and had increases in immunoglobulins M and subsequently G. Liver, spleen, bone marrow, and lymph nodes were the principal organs containing numerous parasitized macrophages. The owl monkey was highly susceptible to L. donovani infection and should be a useful animal model for the study of visceral leishmaniasis.

Tritrichomonas mobilensis n. sp. (Zoomastigophorea: Trichomonadida) from the Bolivian squirrel monkey Saimiri boliviensis boliviensis

A trichomonad flagellate, Tritrichomonas mobilensis n. sp., is described from the large intestine of the squirrel monkey, Saimiri boliviensis boliviensis. The organism has a lanceolate body 7-10.5 micrometers in length; a well developed undulating membrane; a stout, tubular axostyle with periaxostylar rings that terminate in a cone-shaped segment projecting from the posterior end of the cell; and a moderately wide costa. The anterior flagella are about as long as the body, and the recurrent flagellum is of the acroneme type. All its characteristics suggest that the new species belongs in the Tritrichomonas augusta type of the subfamily Tritrichomonadinae.

Adaptation of the Indochina I/CDC strain of Plasmodium falciparum to the squirrel monkey (Saimiri sciureus)

The Indochina I/CDC strain of Plasmodium falciparum was linearly passaged in squirrel monkeys (Saimiri sciureus) of 3 phenotypes. Splenectomized monkeys of Guyanan and Peruvian type developed high density parasitemias, but considerably lower than the mean peak parasitemia (greater than 10(6)/mm3) in Bolivian phenotype squirrel monkeys. Spleen-intact Bolivian and Peruvian squirrel monkeys all developed potentially lethal infections after linear passage of parasites from Saimiri and Aotus. For the evaluation of induced immunity to P. falciparum, the Indochina I/CDC strain in Saimiri will be a valuable model system.

Trypanosoma cruzi and Trypanosoma rangeli in Saimiri sciureus from Bolivia and Saguinus mistax from Brazil

Examination of blood films for trypanosomes in primates housed at the Tulane University Delta Regional Primate Research Center showed that 47% (32/68) of the Bolivian Saimiri sciureus and 51% (68/135) of Brazilian Saguinus mistax harbored one or more types: Trypanosoma (Schizotrypanum) cruzi in 6% to 7% and Trypanosoma (Herpetosoma) spp. or Trypanosoma (Megatrypanum) spp. in 39% and 45%, respectively. Trypanosomes were isolated from a sample of the infected monkeys and morphobiological studies were carried out. Both T. cruzi and Trypanosoma rangeli were demonstrated. The transmission of T. rangeli by Rhodnius prolixus, Rhodnius neglectus, and Triatoma infestans was assessed: only R. prolixus transmitted the infection by bite. T. rangeli has not been found previously in Bolivia, nor has any trypanosome been reported previously in Saguinus mistax.

Studies on a newly isolated strain of Plasmodium brasilianum in Aotus and Saimiri monkeys and different anophelines

A strain of Plasmodium brasilianum was isolated from an Aotus vociferans monkey from Peru. The parasite readily infected Aotus monkeys from Bolivia and Columbia and Saimiri sciureus monkeys from Peru and Bolivia. Highest level mosquito infections were obtained by feeding on the Saimiri monkeys. The most susceptible mosquito was Anopheles freeborni, followed by Anopheles dirus, Anopheles stephensi, Anopheles gambiae, Anopheles culicifacies, Anopheles maculatus and Anopheles albimanus. Anopheles quadrimaculatus were also susceptible to infection. Degenerating oocysts were observed in An. dirus mosquitoes infected with this parasite. Transmission via the bites of infected An. maculatus mosquitoes was obtained to 3 Bolivian Saimiri monkeys; prepatent periods were 27, 27, and 29 days.

Comparison of Plasmodium falciparum infections in Panamanian and Colombian owl monkeys

Parameters of blood-induced infections of the Vietnam Oak Knoll, Vietnam Smith, and Uganda Palo Alto strains of Plasmodium falciparum studied in 395 Panamanian owl monkeys in this laboratory between 1976-1984 were compared with those reported from another laboratory for 665 Colombian owl monkeys, studied between 1968-1975, and, at the time, designated Aotus trivirgatus griseimembra. The virulence of these strains was less in Panamanian than in Colombian owl monkeys, as indicated by lower mortality rates of the Panamanian monkeys during the first 30 days of patency. Maximum parasitemias of the Vietnam Smith and Uganda Palo Alto strain, in Panamanian owl monkeys dying during the first 15 days of patent infection, were significantly higher than in Colombian owl monkeys. Panamanian owl monkeys that survived the primary attack had significantly higher maximum parasitemias than the surviving Colombian owl monkeys. Peak parasitemias were attained significantly earlier after patency in Panamanian than in Colombian owl monkeys, irrespective of the strain of P. falciparum. More Panamanian than Colombian owl monkeys evidenced self-limited infection after the primary attack of either the Vietnam Smith or Uganda Palo Alto strain. The duration of the primary attacks and recrudescences were significantly shorter in Panamanian than in Colombian owl monkeys. Mean peak parasitemias during recrudescence were usually higher in Panamanian owl monkeys than in Colombian monkeys. Differences of infection parameters were probably attributable, in part, to geographical origin of the two monkey hosts and parasite strains.

Infection of Aotus azarae boliviensis monkeys with different strains of Plasmodium vivax

Sixty-seven splenectomized Aotus azarae boliviensis were infected with strains of Plasmodium vivax from Southeast Asia (2), New Guinea (2), North Korea (1), and Central America (3). Maximum parasitemias varied among the different strains, with the mean maximum parasitemia for the primary infection period being 16,200 per mm3. Animals previously infected with Plasmodium falciparum and Plasmodium malariae produced maximum parasitemias of 30,200 and 11,900 per mm3, respectively. Gametocytes infective to Anopheles freeborni mosquitoes were produced with 7 of the 8 strains examined.

Studies on the North Korean strain of Plasmodium vivax in Aotus monkeys and different anophelines

Twenty-two Aotus monkeys of different karyotypes were infected with the North Korean strain of Plasmodium vivax. Aotus lemurinus griseimembra animals from Colombia produced higher maximum parasitemias and more readily infected mosquitoes than did Aotus monkeys from Bolivia (K-VI) or Peru (K-V and K-X). Comparative feedings indicated that the most susceptible mosquito species was Anopheles stephensi, followed by An. gambiae, An. dirus, An. freeborni, An. quadrimaculatus, An. culicifacies, and An. maculatus.