Primate malarias as a model for cross-species parasite transmission

Parasites regularly switch into new host species, representing a disease burden and conservation risk to the hosts. The distribution of these parasites also gives insight into characteristics of ecological networks and genetic mechanisms of host-parasite interactions. Some parasites are shared across many species, whereas others tend to be restricted to hosts from a single species. Understanding the mechanisms producing this distribution of host specificity can enable more effective interventions and potentially identify genetic targets for vaccines or therapies. As ecological connections between human and local animal populations increase, the risk to human and wildlife health from novel parasites also increases. Which of these parasites will fizzle out and which have the potential to become widespread in humans? We consider the case of primate malarias, caused by Plasmodium parasites, to investigate the interacting ecological and evolutionary mechanisms that put human and nonhuman primates at risk for infection. Plasmodium host switching from nonhuman primates to humans led to ancient introductions of the most common malaria-causing agents in humans today, and new parasite switching is a growing threat, especially in Asia and South America. Based on a wild host-Plasmodium occurrence database, we highlight geographic areas of concern and potential areas to target further sampling. We also discuss methodological developments that will facilitate clinical and field-based interventions to improve human and wildlife health based on this eco-evolutionary perspective.

Genetic evidence for the role of non-human primates as reservoir hosts for human schistosomiasis

Background

Schistosomiasis is a chronic parasitic disease, that affects over 207 million people and causes over 200,000 deaths annually, mainly in sub-Saharan Africa. Although many health measures have been carried out to limit parasite transmission, significant numbers of non-human primates such as Chlorocebus aethiops (Ch. aethiops) (vervet) and Papio anubis (baboon) are infected with S. mansoni, notably in Ethiopia, where they are expected to have potentially significant implications for transmission and control efforts.

Objective

The objective of this study was to assess and compare the genetic diversity and population structure of S. mansoni isolates from human and non-human primates free-ranging in close proximity to villages in selected endemic areas of Ethiopia.

Methods

A cross-sectional study was conducted in three transmission sites: Bochesa, Kime and Fincha. A total of 2,356 S. mansoni miracidia were directly isolated from fecal specimens of 104 hosts (i.e. 60 human hosts and 44 non-human primates). We performed DNA extraction and PCR amplification using fourteen microsatellite loci.

Results

At population scale we showed strong genetic structure between the three sample sites. At the definitive host scale, we observed that host factors can shape the genetic composition of parasite infra-populations. First, in male patients, we observed a positive link between parasite genetic diversity and the age of the patients. Second, we observed a difference in genetic diversity which was high in human males, medium in human females and low in non-human primates (NHPs). Finally, whatever the transmission site no genetic structure was observed between human and non-human primates, however, there appears to be little barriers, if any, host specificity of the S. mansoni populations with cross-host infections.

Conclusion

Occurrence of infection of a single host with multiple S. mansoni strains and inter- and intra-host genetic variations was observed. Substantial genetic diversity and gene flow across the S. mansoni population occurred at each site and non-human primates likely play a role in local transmission and maintenance of infection. Therefore, public health and wildlife professionals should work together to improve disease control and elimination strategies.

Schistosomiasis is a chronic disease caused by flukes (trematodes). The definitive host spectrum of schistosomes, whether human, non-human primates (NHPs) or other mammals, is highly dependent on the schistosome species concerned. Genetic diversity and population structure studies of S. mansoni have provided insights into the variation of natural populations. Understanding S. mansoni genetic diversity and population structure of isolates from human and non-human primate hosts living in close proximity showed the occurrence of infection of a single host with multiple S. mansoni strains and inter- and intra-host genetic variations. In this article, the researchers assert the fact that genetic approach reveals that parasites from the three different sites are independent. Thus, we could consider the three sites as geographical replicates showing the influence of NHPs in parasitic transmission in Ethiopia. This study provides insights into the epidemiology, genetic diversity and population structure of S. mansoni in human and non-human primates in Ethiopia, all of which are crucial for the control of schistosomiasis.

Molecular prevalence and subtyping of Cryptosporidium hominis among captive long-tailed macaques (Macaca fascicularis) and rhesus macaques (Macaca mulatta) from Hainan Island, southern China

BACKGROUND

Cryptosporidium is an important zoonotic parasite that is commonly found in non-human primates (NHPs). Consequently, there is the potential for transmission of this pathogen from NHPs to humans. However, molecular characterization of the isolates of Cryptosporidium from NHPs remains relatively poor. The aim of the present work was to (i) determine the prevalence; and (ii) perform a genetic characterization of the Cryptosporidium isolated from captive Macaca fascicularis and M. mulatta on Hainan Island in southern China.

METHODS

A total of 223 fresh fecal samples were collected from captive M. fascicularis (n = 193) and M. mulatta (n = 30). The fecal specimens were examined for the presence of Cryptosporidium spp. by polymerase chain reaction (PCR) and sequencing of the partial small subunit (SSU) rRNA gene. The Cryptosporidium-positive specimens were subtyped by analyzing the 60-kDa glycoprotein (gp60) gene sequence.

RESULTS

Cryptosporidium spp. were detected in 5.7% (11/193) of M. fascicularis. All of the 11 Cryptosporidium isolates were identified as C. hominis. Subtyping of nine of these isolates identified four unique gp60 subtypes of C. hominis. These included IaA20R3a (n = 1), IoA17a (n = 1), IoA17b (n = 1), and IiA17 (n = 6). Notably, subtypes IaA20R3a, IoA17a, and IoA17b were novel subtypes which have not been reported previously.

CONCLUSIONS

To our knowledge, this is the first reported detection of Cryptosporidium in captive M. fascicularis from Hainan Island. The molecular characteristics and subtypes of the isolates here provide novel insights into the genotypic variation in C. hominis.

Why Do Some Primate Malarias Relapse?

Relapse may have evolved in malaria as a mechanism to avoid suppression by more virulent species in mixed infections, thereby increasing transmission opportunities. Later evolution of long latency in Plasmodium vivax was a necessary adaptation as early hominins moved to colder areas with shorter mosquito breeding seasons. Genetic diversity was maintained through heterologous hypnozoite activation.

Climate, environment and transmission of malaria

Malaria, the most common parasitic disease in the world, is transmitted to the human host by mosquitoes of the genus Anopheles. The transmission of malaria requires the interaction between the host, the vector and the parasite.The four species of parasites responsible for human malaria are Plasmodium falciparum, Plasmodium ovale, Plasmodium malariae and Plasmodium vivax. Occasionally humans can be infected by several simian species, like Plasmodium knowlesi, recognised as a major cause of human malaria in South-East Asia since 2004. While P. falciparum is responsible for most malaria cases, about 8% of estimated cases globally are caused by P. vivax. The different Plasmodia are not uniformly distributed although there are areas of species overlap. The life cycle of all species of human malaria parasites is characterised by an exogenous sexual phase in which multiplication occurs in several species of Anopheles mosquitoes, and an endogenous asexual phase in the vertebrate host. The time span required for mature oocyst development in the salivary glands is quite variable (7-30 days), characteristic of each species and influenced by ambient temperature. The vector Anopheles includes 465 formally recognised species. Approximately 70 of these species have the capacity to transmit Plasmodium spp. to humans and 41 are considered as dominant vector capable of transmitting malaria. The intensity of transmission is dependent on the vectorial capacity and competence of local mosquitoes. An efficient system for malaria transmission needs strong interaction between humans, the ecosystem and infected vectors. Global warming induced by human activities has increased the risk of vector-borne diseases such as malaria. Recent decades have witnessed changes in the ecosystem and climate without precedent in human history although the emphasis in the role of temperature on the epidemiology of malaria has given way to predisposing conditions such as ecosystem changes, political instability and health policies that have reduced the funds for vector control, combined with the presence of migratory flows from endemic countries.

ACANTHOCEPHALANS PROSTHENORCHIS CF. ELEGANS (ARCHIACANTHOCEPHALA: OLIGACANTHORHYNCHIDAE), PARASITES OF PRIMATES IN THE MOSCOW ZOO

Acanthocephalans Prosthenorchis cf. elegans were found in primates in the Moscow Zoo. The larvae of these parasites (cistacanths) were found in cockroaches Blattella germanica that had been captured near aviaries of infected animals. Descriptions and drawings of adult parasites and their larvae are given. Analysis of Prosthenorchis cf. elegans genes ITS 1 rDNA and CO 1 mtDNA shows phylogenetic relations of these parasites with several representatives of the class Archiacanthocephala. The obtained molecular data, however, do not support the monophyly of the family Oligacanthorhynchidae and the order Oligacanthorhynchida.

Nodular Worm Infections in Wild Non-human Primates and Humans Living in the Sebitoli Area (Kibale National Park, Uganda): Do High Spatial Proximity Favor Zoonotic Transmission?

BACKGROUND

Nodular Oesophagostomum genus nematodes are a major public health concern in some African regions because they can be lethal to humans. Their relatively high prevalence in people has been described in Uganda recently. While non-human primates also harbor Oesophagostomum spp., the epidemiology of this oesophagostomosis and the role of these animals as reservoirs of the infection in Eastern Africa are not yet well documented.

METHODOLOGY/PRINCIPAL FINDINGS

The present study aimed to investigate Oesophagostomum infection in terms of parasite species diversity, prevalence and load in three non-human primates (Pan troglodytes, Papio anubis, Colobus guereza) and humans living in close proximity in a forested area of Sebitoli, Kibale National Park (KNP), Uganda. The molecular phylogenetic analyses provided the first evidence that humans living in the Sebitoli area harbored O. stephanostomum, a common species in free-ranging chimpanzees. Chimpanzees were also infected by O. bifurcum, a common species described in human populations throughout Africa. The recently described Oesophagostomum sp. found in colobine monkeys and humans and which was absent from baboons in the neighboring site of Kanyawara in KNP (10 km from Sebitoli), was only found in baboons. Microscopic analyses revealed that the infection prevalence and parasite load in chimpanzees were significantly lower in Kanyawara than in Sebitoli, an area more impacted by human activities at its borders.

CONCLUSIONS/SIGNIFICANCE

Three different Oesophagostomum species circulate in humans and non-human primates in the Sebitoli area and our results confirm the presence of a new genotype of Oesophagostomum recently described in Uganda. The high spatiotemporal overlap between humans and chimpanzees in the studied area coupled with the high infection prevalence among chimpanzees represent factors that could increase the risk of transmission for O. stephanostomum between the two primate species. Finally, the importance of local-scale research for zoonosis risk management is important because environmental disturbance and species contact can differ, leading to different parasitological profiles between sites that are close together within the same forest patches.

Simian malaria in wild macaques: first report from Hulu Selangor district, Selangor, Malaysia

BACKGROUND

Malaria is a vector-borne parasitic disease which is prevalent in many developing countries. Recently, it has been found that Plasmodium knowlesi, a simian malaria parasite can be life-threatening to humans. Long-tailed macaques, which are widely distributed in Malaysia, are the natural hosts for simian malaria, including P. knowlesi. The aim of the present study was to determine the prevalence of simian malaria parasites in long-tailed macaques in the district of Hulu Selangor, Selangor, Malaysia.

METHODS

A total of 70 blood samples were collected from Macaca fascicularis dwelling in the forest of Hulu Selangor by the Department of Wildlife and National Parks Peninsular Malaysia, Kuala Lumpur, Malaysia. DNA was extracted using PureLink™ Genomic DNA Kits. Conventional and nested PCR were used to detect the genus and species of Plasmodium parasites respectively. In addition, phylogenetic analysis was carried out to confirm the species of Plasmodium parasites.

RESULTS

Thirty-five (50 %) of the 70 samples were positive for Plasmodium using genus-specific primers. These positive samples were then subjected to nested PCR targeting the 18S ribosomal RNA genes to detect all five simian malaria parasites: namely, P. knowlesi, Plasmodium inui, Plasmodium cynomolgi, Plasmodium fieldi, and Plasmodium coatneyi. All five species of simian malaria parasites were detected. Of these, P. inui was the predominant (65.7 %), followed by P. knowlesi (60 %), P. cynomolgi (51.4 %) P. coatneyi (45.7 %) and P. fieldi (2.9 %). A total of nine macaques had mono-infection with P. knowlesi (four), P. cynomolgi (two), P. coatneyi (two) and P. fieldi (one). Eleven of the macaques had dual infections while 12 had triple infections. Three macaques were infected with four species of Plasmodium. Molecular and phylogenetic analysis confirmed the five species of Plasmodium parasites.

CONCLUSION

This study has provided evidence to elucidate the presence of transmission of malaria parasites among the local macaques in Hulu Selangor. Since malaria is a zoonosis, it is important to determine the new control strategies for the control of malaria.

Screening wild and semi-free ranging great apes for putative sexually transmitted diseases: Evidence of Trichomonadidae infections

Sexually transmitted diseases (STDs) can persist endemically, are known to cause sterility and infant mortality in humans, and could have similar impacts in wildlife populations. African apes (i.e., chimpanzees, bonobos, and to a lesser extent gorillas) show multi-male mating behavior that could offer opportunities for STD transmission, yet little is known about the prevalence and impact of STDs in this endangered primate group. We used serology and PCR-based detection methods to screen biological samples from wild and orphaned eastern chimpanzees and gorillas (N = 172 individuals, including adults, and juveniles) for four classes of pathogens that either commonly cause human STDs or were previously detected in captive apes: trichomonads, Chlamydia spp., Treponema pallidum (syphilis and yaws), and papillomaviruses. Based on results from prior modeling and comparative research, we expected STD prevalence to be highest in females versus males and in sexually mature versus immature individuals. All samples were negative for Chlamydia, Treponema pallidum, and papillomaviruses; however, a high percentage of wild chimpanzee urine and fecal samples showed evidence of trichomonads (protozoa). Analysis revealed that females were more likely than males to have positive urine-but not fecal-samples; however, there was no evidence of age (sexual maturity) differences in infection status. Sequence analysis of chimpanzee trichomonad samples revealed a close relationship to previously described trichomonads within the genus Tetratrichomonas. Phylogenetic comparisons to archived sequences from multiple vertebrate hosts suggests that many of the chimpanzee parasites from our study are likely transmitted via fecal-oral contact, but the transmission of some Tetratrichomonas sequence-types remains unknown and could include sexual contact. Our work emphasizes that only a fraction of infectious agents affecting wild apes are presently known to science, and that further work on great ape STDs could offer insights for the management of endangered great apes and for understanding human STD origins.

Multilocus typing of Cryptosporidium spp. and Giardia duodenalis from non-human primates in China

Non-human primates (NHPs) are commonly infected with Cryptosporidium spp. and Giardia duodenalis. However, molecular characterisation of these pathogens from NHPs remains scarce. In this study, 2,660 specimens from 26 NHP species in China were examined and characterised by PCR amplification of 18S rRNA, 70kDa heat shock protein (hsp70) and 60kDa glycoprotein (gp60) gene loci for Cryptosporidium; and 1,386 of the specimens by ssrRNA, triosephosphate isomerase (tpi) and glutamate dehydrogenase (gdh) gene loci for Giardia. Cryptosporidium was detected in 0.7% (19/2660) specimens of four NHP species including rhesus macaques (0.7%), cynomolgus monkeys (1.0%), slow lorises (10.0%) and Francois' leaf monkeys (6.7%), belonging to Cryptosporidium hominis (14/19) and Cryptosporidium muris (5/19). Two C. hominis gp60 subtypes, IbA12G3 and IiA17 were observed. Based on the tpi locus, G. duodenalis was identified in 2.2% (30/1,386) of specimens including 2.1% in rhesus macaques, 33.3% in Japanese macaques, 16.7% in Assam macaques, 0.7% in white-headed langurs, 1.6% in cynomolgus monkeys and 16.7% in olive baboons. Sequence analysis of the three targets indicated that all of the Giardia-positive specimens belonged to the zoonotic assemblage B. Highest sequence polymorphism was observed at the tpi locus, including 11 subtypes: three known and eight new ones. Phylogenetic analysis of the subtypes showed that most of them were close to the so-called subtype BIV. Intragenotypic variations at the gdh locus revealed six types of sequences (three known and three new), all of which belonged to so-called subtype BIV. Three specimens had co-infection with C. hominis (IbA12G3) and G. duodenalis (BIV). The presence of zoonotic genotypes and subtypes of Cryptosporidium spp. and G. duodenalis in NHPs suggests that these animals can potentially contribute to the transmission of human cryptosporidiosis and giardiasis.

Humans and great apes cohabiting the forest ecosystem in central african republic harbour the same hookworms

Background

Hookworms are important pathogens of humans. To date, Necator americanus is the sole, known species of the genus Necator infecting humans. In contrast, several Necator species have been described in African great apes and other primates. It has not yet been determined whether primate-originating Necator species are also parasitic in humans.

Methodology/Principal Findings

The infective larvae of Necator spp. were developed using modified Harada-Mori filter-paper cultures from faeces of humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. The first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA and partial cytochrome c oxidase subunit 1 (cox1) gene of mtDNA obtained from the hookworm larvae were sequenced and compared. Three sequence types (I–III) were recognized in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A–C). The combinations determined were I-A, II-B, II-C, III-B and III-C. Combination I-A, corresponding to N. americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans, western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%.

Conclusions/Significance

The distinctness of ITS sequence variants and high number of pairwise nucleotide differences among cox1 variants indicate the possible presence of several species of Necator in both humans and great apes. We conclude that Necator hookworms are shared by humans and great apes co-habiting the same tropical forest ecosystems.

We conducted analyses of DNA sequences obtained from the infective larvae of Necator spp. from humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. Three sequence types (I–III) were recognized in the in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A–C). I-A, II-B, II-C, III-B, III-C combinations were determined. Combination I-A, corresponding to Necator americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans (local inhabitants and researchers), western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%, suggesting that each type represents a distinct species. This is the first molecular evidence that Necator species found in great apes can infect humans and vice versa.

Novel insights into the genetic diversity of Balantidium and Balantidium-like cyst-forming ciliates

Balantidiasis is considered a neglected zoonotic disease with pigs serving as reservoir hosts. However, Balantidium coli has been recorded in many other mammalian species, including primates. Here, we evaluated the genetic diversity of B. coli in non-human primates using two gene markers (SSrDNA and ITS1-5.8SDNA-ITS2). We analyzed 49 isolates of ciliates from fecal samples originating from 11 species of captive and wild primates, domestic pigs and wild boar. The phylogenetic trees were computed using Bayesian inference and Maximum likelihood. Balantidium entozoon from edible frog and Buxtonella sulcata from cattle were included in the analyses as the closest relatives of B. coli, as well as reference sequences of vestibuliferids. The SSrDNA tree showed the same phylogenetic diversification of B. coli at genus level as the tree constructed based on the ITS region. Based on the polymorphism of SSrDNA sequences, the type species of the genus, namely B. entozoon, appeared to be phylogenetically distinct from B. coli. Thus, we propose a new genus Neobalantidium for the homeothermic clade. Moreover, several isolates from both captive and wild primates (excluding great apes) clustered with B. sulcata with high support, suggesting the existence of a new species within this genus. The cysts of Buxtonella and Neobalantidium are morphologically indistinguishable and the presence of Buxtonella-like ciliates in primates opens the question about possible occurrence of these pathogens in humans.

Survey of Plasmodium spp. in free-ranging neotropical primates from the Brazilian Amazon region impacted by anthropogenic actions

This study investigated Plasmodium spp. infection in free-ranging neotropical primates from Brazilian Amazon regions under the impact of major anthropogenic actions. Blood samples from 19 new world primates were collected and analyzed with microscopic and molecular procedures. The prevalence of Plasmodium infection was 21.0% (4/19) and PCR positive samples were identified as P. brasilianum. Considering the social-economic changes that the Amazon is facing, the prevalence of P. brasilianum infection highlights the necessity to closely monitor the movement of both human and non-human primate populations, in order to mitigate pathogen exposure and the introduction of new agents into previously naïve areas.

The genetic diversity of Plasmodium malariae and Plasmodium brasilianum from human, simian and mosquito hosts in Brazil

Plasmodium malariae is a protozoan parasite that causes malaria in humans and is genetically indistinguishable from Plasmodium brasilianum, a parasite infecting New World monkeys in Central and South America. P. malariae has a wide and patchy global distribution in tropical and subtropical regions, being found in South America, Asia, and Africa. However, little is known regarding the genetics of these parasites and the similarity between them could be because until now there are only a very few genomic sequences available from simian Plasmodium species. This study presents the first molecular epidemiological data for P. malariae and P. brasilianum from Brazil obtained from different hosts and uses them to explore the genetic diversity in relation to geographical origin and hosts. By using microsatellite genotyping, we discovered that of the 14 human samples obtained from areas of the Atlantic forest, 5 different multilocus genotypes were recorded, while in a sample from an infected mosquito from the same region a different haplotype was found. We also analyzed the longitudinal change of circulating plasmodial genetic profile in two untreated non-symptomatic patients during a 12-months interval. The circulating genotypes in the two samples from the same patient presented nearly identical multilocus haplotypes (differing by a single locus). The more frequent haplotype persisted for almost 3 years in the human population. The allele Pm09-299 described previously as a genetic marker for South American P. malariae was not found in our samples. Of the 3 non-human primate samples from the Amazon Region, 3 different multilocus genotypes were recorded indicating a greater diversity among isolates of P. brasilianum compared to P. malariae and thus, P. malariae might in fact derive from P. brasilianum as has been proposed in recent studies. Taken together, our data show that based on the microsatellite data there is a relatively restricted polymorphism of P. malariae parasites as opposed to other geographic locations.

Low prevalence of Chagas parasite infection in a nonhuman primate colony in Louisiana

Chagas disease, an important cause of heart disease in Latin America, is caused by the parasite Trypanosoma cruzi, which typically is transmitted to humans by triatomine insects. Although autochthonous transmission of the Chagas parasite to humans is rare in the United States, triatomines are common, and more than 20 species of mammals are infected with the Chagas parasite in the southern United States. Chagas disease has also been detected in colonies of nonhuman primates (NHP) in Georgia and Texas, and heart abnormalities consistent with Chagas disease have occurred at our NHP center in Louisiana. To determine the level of T. cruzi infection, we serologically tested 2157 of the approximately 4200 NHP at the center; 34 of 2157 primates (1.6%) tested positive. Presence of the T. cruzi parasite was confirmed by hemoculture in 4 NHP and PCR of the cultured parasites. These results strongly suggest local transmission of T. cruzi, because most of the infected NHP were born and raised at this site. All 3 species of NHP tested yielded infected animals, with significantly higher infection prevalence in pig-tailed macaques, suggesting possible exploration of this species as a model organism. The local T. cruzi strain isolated during this study would enhance such investigations. The NHP at this center are bred for use in scientific research, and the effects of the Chagas parasite on infected primates could confuse the interpretation of other studies.

[Nematodes of the genus Oesophagostomum: an emerging risk for humans and apes in Africa?]

Nematodes of the genus Oesophagostomum are common intestinal parasites found in cattle, pigs and primates. They can cause severe illness, resulting from the formation of granulomas, caseous lesions and abscesses in the intestinal wall. Human oesophagostomosis is endemic in northern Ghana and Togo. In these regions, epidemiological investigations have been conducted to determine the biological characteristics, transmission dynamics and optimal management of clinical cases. Nodular oesophagostomosis has also been described in free-ranging chimpanzees and gorillas. Clinical signs associated with nodules have been observed in great apes raised in sanctuaries, while the health status of their wild counterparts does not seem to be significantly affected It has been suggested that some nonhuman primates may act as reservoirs for human oesophagostomosis. In Ghana, identification of genetic differences among Oesophagostomum nematodes infecting different primate hosts suggests that oesophagostomosis is a rare zoonosis. In Uganda, where the situation is diferent, cross-infection is probably more frequent.

Characterization of peripheral blood T lymphocyte subsets in Chinese rhesus macaques with repeated or long-term infection with Plasmodium cynomolgi

T lymphocytes play a vital role in antimalaria immunity, but there is little information about the role of T cells in malaria infection. In order to explore the profile of T cells in malaria immunity, we infected Chinese rhesus macaques with the malaria parasite (Plasmodium cynomolgi) and examined the dynamics of T cell subsets. Both repeated and long-term infections were involved. Our results showed that the monkeys in the repeated infection group acquired protective immunity through primary infection, which was evidenced by a much lower parasitemia, milder anemia, and milder fever during reinfection; the monkeys in the long-term infection group also developed protective immunity, but this was not sufficient to eliminate the parasite. The total counts of leukocytes, neutrophils, CD3+ T cells, CD4+ or CD8+ T cells, and naïve and memory CD4+ and CD8+ T cells declined during the acute phase of malaria but increased after the parasite was controlled. The total number of activated CD4+ T cells significantly increased during malaria in animals with a long-term infection, which remained at least 3 months after the termination of malaria. However, the activated CD4+ T cells decreased during the acute phase of infection in the repeated infection group and converted to preinfection levels after malaria was cured. Regulatory CD4+ T cells continued to increase during the malaria infections and quickly reverted to preinfection levels after the parasite was controlled. Our study provides a systematic analysis of the kinetic profiles of T lymphocyte subsets during malaria infections and provides some experimental insight into malaria immunology.

[Emerging and spread of the fifth Plasmodium spp. pathogenic for human malaria: Plasmodium knowlesi]

The beginning of the third millennium has been characterized by the emerging and progressive characterization of a novel malaria Plasmodium pathogen of simian origin (Plasmodium knowlesi), which now represents the fifth human malaria parasite. Evolutionary, environmental, and diagnostic-clinical features are briefly outlined on the ground of the most recent literature evidences.

A legacy of low-impact logging does not elevate prevalence of potentially pathogenic protozoa in free-ranging gorillas and chimpanzees in the Republic of Congo: logging and parasitism in African apes

Many studies have examined the long-term effects of selective logging on the abundance and diversity of free-ranging primates. Logging is known to reduce the abundance of some primate species through associated hunting and the loss of food trees for frugivores; however, the potential role of pathogens in such primate population declines is largely unexplored. Selective logging results in a suite of alterations in host ecology and forest structure that may alter pathogen dynamics in resident wildlife populations. In addition, environmental pollution with human fecal material may present a risk for wildlife infections with zoonotic protozoa, such as Cryptosporidium and Giardia. To better understand this interplay, we compared patterns of infection with these potentially pathogenic protozoa in sympatric western lowland gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) in the undisturbed Goualougo Triangle of Nouabalé-Ndoki National Park and the adjacent previously logged Kabo Concession in northern Republic of Congo. No Cryptosporidium infections were detected in any of the apes examined and prevalence of infection with Giardia was low (3.73% overall) and did not differ between logged and undisturbed forest for chimpanzees or gorillas. These results provide a baseline for prevalence of these protozoa in forest-dwelling African apes and suggest that low-intensity logging may not result in long-term elevated prevalence of potentially pathogenic protozoa.

Parasitic zoonoses at the rodent-captive primate-human health interface

Parasitic diseases at the wildlife/primate/human interface are of particular importance in zoological gardens. Better understanding of the types of wildlife parasites that do persist in zoological gardens, and drives that lead to increases in prevalence or impacts, can point to new strategies for limiting the risk of human and captive primates' exposure in zoo centres. Also, it improves our understanding of the underlying mechanisms that influence the emergence of parasitic diseases. As wild animals and humans come into greater contact with each other, the risk posed by multi-host parasites for humans, captive primates, and wildlife populations increases. Despite strong public awareness of the fact that wildlife constitutes a large and often unknown reservoir of most emerging infectious diseases, animal-human interaction has not been addressed. Herein, the potential for cross-species parasite transmission between the wild rodents, captive primates and humans is considered using the current literature and medical records. Additionally, some aspects of the interface among wildlife, captive primates and humans and its impacts on human health are discussed. Finally, priorities for future research are identified, including identifying those parasites for which multi-host interaction is likely to have the greatest impact.

Gastrointestinal protozoa in non-human primates of four zoological gardens in Belgium

Gastrointestinal parasites are important infectious causes of diarrhoea in captive non-human primates (NHP). However, prevalence data of gastrointestinal parasites in zoological gardens are scarce. Therefore, a cross-sectional survey was conducted to estimate the occurrence of gastrointestinal parasites in NHP of four zoological gardens in Belgium. Between August 2004 and April 2006, 910 faecal samples were collected from 222 animals housed in 39 groups. The 31 species involved were representatives of prosimians, New World (NW) monkeys, Old World (OW) monkeys and apes. Because individual sampling was impossible, a statistical simulation was performed to estimate a sufficient sample size. All samples were microscopically examined after an acetic acid-ether concentration. Differences in host species susceptibility were examined by non-parametric tests. Entamoeba spp. (44%) and Giardia spp. (41%) were the most prevalent species. Other parasites detected were Endolimax nana (36%), Chilomastix mesnili (21%), Balantidium coli (13%), Trichuris spp. (10%), Iodamoeba bütschlii (5%) and Strongyloides spp. (5%). Parasites for which a significant difference in susceptibility at the level of host taxonomy was noted were Entamoeba spp. (p<0.001) and C. mesnili (p<0.05). Samples containing Entamoeba spp. were the most prevalent in OW monkeys (p<0.0083). Samples collected from OW monkeys contained the highest number of parasite species (p<0.0083).

Trypanosoma cruzi prevalence and epidemiologic trends in lemurs on St. Catherines Island, Georgia

Lemurs on St. Catherines Island, Georgia were tested for Trypanosoma cruzi infection to develop a better understanding of the epizootiology of the parasite in nonhuman primates in the southeastern United States. Fifty-six ring-tailed (Lemur catta), blue-eyed black (Eulemur macaco flavifrons), and black-and-white ruffed (Varecia variegata variegata) lemurs were tested by hemoculture and serology to determine the prevalence of T. cruzi in the population. Of those tested 3 (5%) were identified as culture positive and 25 (44.6%) as seropositive. When hemoculture results were compared with those from a similar study performed in 1997, prevalence remained unchanged. Genetic characterization of the 3 culture isolates indicated they belong to the T. cruzi IIa group, which is identical to strains previously isolated from raccoons on the island. Despite the occurrence of T. cruzi in the population, there was no evidence that the health of the lemurs was compromised as a result of infection. Based upon prevalence and available breeding records we speculate that both vertical and vector-mediated transmission play significant roles in the epidemiology of T. cruzi on the island. This also represents the first report of autochthonous infection in blue-eyed black and black-and-white ruffed lemurs.

Morphological variability withinOesophagostomum bifurcumamong different primate species from Ghana

AdultOesophagostomum bifurcum(Nematoda: Strongylida) from human and non-human primates from Ghana were compared in order to investigate the extent of morphological variability within the species. Using analysis of variance and principal component analysis, significant differences in morphological characters (such as parasite length, width, length of the oesophagus and length of spicules) were demonstrated betweenO. bifurcumworms from humans, the Mona, Patas or Green monkey and/or Olive baboons. These findings suggest thatO. bifurcumfrom different species of primate host represent distinct population variants, also supported by recent epidemiological and genetic studies ofO. bifurcumfrom such hosts.

Parasites and the evolutionary diversification of primate clades

Coevolutionary interactions such as those between hosts and parasites have been regarded as an underlying cause of evolutionary diversification, but evidence from natural populations is limited. Among primates and other mammalian groups, measures of host diversification rates vary widely among lineages, but comparative studies have not yet identified a reliable explanation for this variation. In this study, we used a comprehensive data set of disease-causing organisms from free-living primates to illustrate how phylogenetic comparative methods can be used to examine mammalian lineage diversity in relation to parasite species richness. Our results provide evidence that the phylogenetic diversity of primate clades is correlated positively with the number of parasite species harbored by each host and that this pattern is largely independent of other host traits that have been shown to influence diversification rates and parasite species richness in primates. We investigated two possible mechanisms that could explain this association, namely that parasites themselves drive host evolutionary diversification through processes linked with sexual selection and that host shifts or host sharing increases parasite species richness among diverse primate clades. Neither parasite species richness nor host diversification is related to measures of sexual selection in primates. Further, we found only partial evidence that more rapidly diversifying host lineages produced increased opportunities for host sharing or host shifting by parasites through mechanisms involving species' geographic range overlap. Thus, our analyses provide evidence for an important link between the evolutionary diversification of primates and the richness of their parasite communities, but other mechanisms, particularly those related to reciprocal selection or coextinction of hosts and parasites, require further investigation.

Trypanosoma cruzi (kinetoplastida Trypanosomatidae): biological heterogeneity in the isolates derived from wild hosts

The course of experimental infection of Swiss mice with 95 sylvatic Trypanosoma cruzi isolates included in TCI or TCII genotype was characterized. The purpose was to verify biological properties and its eventual correspondence with original host species, genotype or zymodeme. The isolates of T. cruzi were 100% infective, 55% resulted in patent parasitemia with 69% (36/52) of mortality. A meaningful biological heterogeneity was observed in both, TCI and TCII isolates. TCII isolates resulted in higher patent parasitemia 64% (38/59), in contrast to the 41% TCI infected Swiss mice (14/34). Parasitemia was not always associated to mortality. Higher biological heterogeneity was observed in T. cruzi II isolates derived from L. rosalia from the Atlantic Coastal Rain forest. TCII isolates derived from marsupials resulted in very similar infection profile in Swiss mice.

Stable infection of primates with Trypanosoma cruzi I and II

In order to better comprehend the putative association between genotype Trypanosoma cruzi II and primates, an evaluation of the infection in free ranging primates and specimens born in captivity from different geographical areas, the Amazon and the Atlantic forest, was carried out. Seroprevalences of the T. cruzi infection among the primates was similar in both biomes (45.5% and 46%). The parasites were isolated from 8 and 4 different species of primates, respectively from the Amazon and Atlantic forest. Multi-locus enzyme electrophoresis (MLEE) typed the isolates from Amazon as zymodeme 1. Mini-exon gene analysis characterized all these isolates as T. cruzi I, the main genotype circulating in the region. In the Atlantic forest, primates infected with TCI and TCII, as well as a mixed infection (TCI and TCII), were detected. These findings prove that primates may maintain stable infections by both genotypes. Moreover, data show that T. cruzi can occur in a wide range of primate genera, independent of their social behaviour, niches or habitats. Considering the high seroprevalence and stability of T. cruzi infection among the primates, these animals play an important role in the maintenance of the parasite in nature.

Definition of genetic markers in nuclear ribosomal DNA for a neglected parasite of primates, Ternidens deminutus (Nematoda: Strongylida) – diagnostic and epidemiological implications

Ternidens deminutus (Strongylida) is a parasitic nematode infecting non-human and human primates in parts of Africa, Asia and the Pacific islands. The present study genetically characterized T. deminutus and defined genetic markers in nuclear ribosomal DNA (rDNA) as a basis for developing molecular-diagnostic tools. The sequences of the second internal transcribed spacer (ITS-2) of rDNA were determined for adult specimens of T. deminutus (Nematoda: Strongylida: Oesophagostominae) from the Olive baboon and the Mona monkey. The length and G+C content of the ITS-2 sequences was 216 bp and approximately 43%, respectively. While there was no sequence variation among individual T. deminutus specimens from the baboon, 6 (2.8%) nucleotide differences were detected in the ITS-2 between the parasite from baboon and that of the Mona monkey, which is similar to the difference (3.2%) between 2 other species of Oesophagostominae (Oesophagostomum bifurcum and O. stephanostomum) from non-human primates, suggesting significant population variation or the existence of cryptic (i.e. hidden) species within T. deminutus . Pairwise comparisons of the ITS-2 sequences of the 2 operational taxonomic units of T. deminutus with previously published ITS-2 sequences for selected members of the subfamilies Oesophagostominae and Chabertiinae indicated that species from primates (including those representing the subgenera Conoweberia and Ihleia) are closely related, in accordance with previous morphological studies. The sequence differences (27-48.3%) in the ITS-2 between the 2 taxonomic units of T. deminutus and hookworms (superfamily Ancylostomatoidea) enabled their identification and delineation by polymerase chain reaction (PCR)-based mutation scanning. The genetic markers in the ITS-2 provide a foundation for improved, PCR-based diagnosis of T. deminutus infections and for investigating the life-cycle, transmission patterns and ecology of this parasite.

High resolution DNA fingerprinting by AFLP to study the genetic variation among Oesophagostomum bifurcum (Nematoda) from human and non-human primates from Ghana

An AFLP approach was established to investigate genetic diversity within Oesophagostomum bifurcum (order Strongylida) from human and non-human primates. Evaluation of different combinations of restriction enzymes (n = 8) and primers (n = 29) demonstrated that the use of HindIII/BglII digested templates and primers with the selective nucleotides + AG/ +AC, respectively, was the most effective for the analysis of O. bifurcum DNA. A total of 63 O. bifurcum adults from human, Patas monkey, Mona monkey and Olive baboon hosts from different geographical regions in Ghana were subjected to analysis using this method. Cluster analysis revealed 4 genetically distinct groups, namely O. bifurcum from the Patas monkey (I), from the Mona monkey (II), from humans (III) and from the Olive baboon (IV). These findings were concordant with those achieved previously using RAPD analysis and supports population genetic substructuring within O. bifurcum according to host species. The results demonstrated the effectiveness of the present AFLP method for establishing genetic variation within O. bifurcum, and indicates its applicability to other parasitic nematodes of human and/or veterinary health importance.

Parastrongylus cantonensis in a nonhuman primate, Florida

Parastrongylus (= Angiostrongylus) cantonensis is a parasitic nematode of Norway rats throughout tropical regions. This parasite is neurotropic and causes disease and death in humans and other mammals. We report the first identification of P. cantonensis as the cause of a debilitating neurologic disease in a captive primate in Florida.

Disseminated Toxoplasmosis in a Captive Ring-Tailed Lemur (Lemur catta)

A 3-yr-old secundiparous female ring-tailed lemur presented to the Auburn University Small Animal Clinic with signs of dyspnea, lethargy, and anorexia. The animal died before she could be examined, and a full necropsy was immediately performed. Provisional necropsy findings included moderate pneumonia and hepatopathy. Acute interstitial pneumonia and focal hepatocellular necrosis were confirmed histologically. Lung impression smears, histopathology, electron microscopy, immunohistochemistry, and tissue culture isolation resulted in a diagnosis of acute disseminated Toxoplasma gondii infection, which was confirmed by polymerase chain reaction. The isolate of T. gondii was avirulent for mice and was named AU Tgl and genetically is type II. The source of the infection remains unclear, but speculation suggests contaminated fruit or blackbirds (Passeriformes: Icteridae) acting as transport hosts for oocysts from nondomestic felids and feral cats on the property.

PARASITOLOGIC ANALYSES OF THE SIFAKA (PROPITHECUS VERREAUXI VERREAUXI) AT BEZA MAHAFALY, MADAGASCAR

A cross-sectional parasitologic survey of a population of wild sifaka (Propithecus verreauxi verreauxi) was conducted at the Beza Mahafaly Special Reserve in southwest Madagascar. Ninety fecal samples were collected from thirty 1- to 30-yr-old male and female sifakas, and the formalin-preserved and polyvinyl alcohol-preserved specimens were examined using the zinc sulfate flotation and formalin-ethyl acetate sedimentation techniques. No intestinal parasites were recovered, possibly because the sifakas are arboreal in a dry, riverine habitat and lack human contact. Low rates of parasitic infection may have contributed to the evolution of later age at first reproduction and longer reproductive lifespan, for body mass, in Propithecus compared with other placental mammals.

A histologic demonstration of siliceous materials in simian lung mite infected lung tissues by microincineration

Approximately 90% of freshly imported macaques and other Old World Monkeys are known to be infected with respiratory mites. The lung associated pigments are integral components of pulmonary acariasis in Old World Monkeys; at least three distinctive pigmental bodies are identified in association with lung mite infection. Two major components of pigments are recently identified as silica by using elemental analysis using a high voltage electron microscope and an energy-dispersive X-ray analysis technique. Since a limited number of infected monkey lung tissues and associated pigments can be examined by this tedious procedure, it was important for us to examine much greater number of specimens to verify our initial observation. Ten microincineration technique described provided a unique and practical way to identify the mineral elements in as many 27 histologic sections within a short span of time. Silica and silicates are heat resistant whereas majority of organic materials including lung mite parasites disintegrated under the extreme temperature. Mineral elements were exclusively located within the polarizable white ash. More than 90% of total pigmental bodies identified were found to be related to siliceous materials in 20 incinerated infected monkey lung tissues whereas five noninfected lungs similarly examined did not reveal any pigmental bodies. Other than a small of fine granular mucin substances which were PAS positive, the majority of lung mite associated pigments such as large granules of hemosiderin, needle-like crystals and other fine granules engulfed by macrophages were identified to be siliceous materials as they have persisted even after microincineration. Mite parasites and other organic materials were completely disintegrated. Similar pigmental bodies examined by microscope X-ray analysis were positive for silicate. This finding suggests that lung mite infection in Old Monkeys apparently predisposed silicosis. Therefore, until the link between lung mite infection and silicosis is clarified, experimental inhalation toxicologic findings in mite-infected Old World monkeys should be interpreted cautiously.

A case of pulmonary acariasis in lung of Japanese macaque

A 20-year-old female Japanese macaque, weighing 8.7 kg, developed severe pulmonary acariasis. Numerous whitish nodules, 2-4 mm, were scattered throughout the lungs. Histologically multifocal granulomatous lesions consisting of a large number of eosinophils, epithelioid cells, foreign body type giant cells, and collagen fibers were aggregated around the mait bodies. Numerous mast cells were also detected in the lesions by toluidine blue staining, and tested positive for tryptase by immunohistochemistry. This may be the first reported case of severe pulmonary acariasis in a Japanese macaque.

Trypanosoma cruzi infection of squirrel monkeys: comparison of blood smear examination, commercial enzyme-linked immunosorbent assay, and polymerase chain reaction analysis as screening tests for evaluation of monkey-related injuries

BACKGROUND AND PURPOSE

Wild-caught New World monkeys (NWM) from Central or South America are often infected with Trypanosoma species, including T. cruzi. In humans, T. cruzi causes Chagas' disease. Even in closed monkey colonies, T. cruzi can be propagated by blood-to-blood exposure, sexual activity, and transplacental transmission. Animal handlers and laboratory staff who deal with blood and tissues from infected NWM are at riskfor acquiring Chagas' disease via accidental exposure.

METHODS

We screened 162 blood samples from wild-caught Saimiri sp. monkeys for Trypanosoma species infections by use of blood smear examination, ELISA, and polymerase chain reaction (PCR) analysis. Blood samples from 19 employees with recent history of monkey-associated injuries also were tested.

RESULTS

Six percent (10/162) of the monkey samples were T. cruzi positive on the basis of blood smear examination results, 10.4% (17/162) were positive by ELISA results, and 26.5% (43/162) were positive by PCR results. Other organisms identified by PCR analysis included T. rangeli in two animals, Plasmodium spp. in two animals (P. malariae confirmed by PCR results) and microfilariae in one animal (morphologically, Mansonella perstans). Evidence of trypanosome infection was not found in the 19 employee samples on the basis of results of any of the three aforementioned tests.

CONCLUSIONS

Close attention must be paid to worker safety where wild-caught NWM are used. The PCR analysis has a clear advantage over conventional techniques (ELISA, blood smear) for screening NWM for trypanosome infections during quarantine and after employee injury.

Development of Alouattamyia baeri (Diptera: Oestridae) from howler monkeys (Primates: Cebidae) on Barro Colorado Island, Panama

The fecundity and development of larval stages of the cuterebrid bot fly A. baeri were studied in an unusual host, remotely related to the primary host. Third-instar Alouattamyia baeri (Shannon & Greene) removed from howler monkeys, Alouatta palliata, were allowed to pupate and then were cultured under controlled conditions. Eclosion occurred after 37.9 +/- 0.4 (mean +/- SE) (male) and 38.2 +/- 0.4 (female) d at 26 degrees C. Five-day-old females were mated using a tethered flight technique and oviposited on ridged filter paper. The total egg complement was 1,399 +/- 243 (n = 2) eggs per female. Eggs were fully embryonated after incubation for 5 d at 26 degrees C. Eggs hatched when warmed in the palm of the hand. Hatching of eggs from an individual batch was asynchronous. Newly hatched larvae would not penetrate intact skin on a rabbit, Oryctolagus cuniculus L. Larvae placed near the nares or on the ocular conjunctiva migrated rapidly from view. Warbles containing larvae were first observed on infested rabbits 5 d after infestation. Development of larvae proceeded until day 39 after infestation, when nearly mature 3rd instars were observed. None of the larvae survived to pupate.

Some gastro-intestinal parasites of zoonotic (public health) importance commonly observed in old world non-human primates in Kenya

A study was undertaken to categorise some gastro-intestinal (GIT) parasites commonly observed in Kenyan non-human primates (NHPs) on the basis of their health implications for humans. Six species of locally available non-human primates, namely olive baboons (Papio cyanocephalus anubis), Vervet monkey (Cercopithecus aethiops), Sykes monkey (Cercopithecus mitis), Black and white colobus (Colobus abyssinicus), Debrazzas monkey (Cercopithecus neglectus) and Grey and Black mangabeys (Cercocebus torquatus and Cercocebus albigena) which were imported from Zaire (Democratic Republic of Congo) were sampled. Simple laboratory methods involving microscopic examination of stained faecal smears were used. Wet faecal smears stained with iodine and unstained controls were used for conventional parasites while acid fast staining was employed to detect Cryptosporidium oocysts. Both helminths and protozoan parasites were detected in varying rates in all primate species. Trichuris sp. was the most frequent helminth followed by Strongyloides fulleborni, Strongyles sp. and Schistosoma mansoni in that order. Entamoeba coli was the most common protozoan followed, respectively, by Balantidiun coli and Entamoeba histolytica. All primate species examined were infected with all the parasites listed except the black and white colobus. Cryptosporidium was found in both clinically normal and diarrhoeic baboons and vervets. Most taxa of parasites observed could prejudice human welfare directly through infection and causation of illness and indirectly through increased cost of livestock production and decreased availability of animal proteins. The potential of some of the agents to cause opportunistic infections in immuno-compromised persons was suggested as a likely threat to man's well-being. This would warrant such person's exemption from high risk operations at primate and other animal facilities in developing countries. Further, specific studies are needed to provide data on the epidemiology, socio-economic impact and pathogenicity of the primate parasites to other species of animals and man.

Cerebrospinal nematodiasis in a white-handed gibbon (Hylobates lar) due to Baylisascaris sp

An adult white-handed gibbon (Hylobates lar) at a zoo in eastern Kansas was euthanized after developing a head tremor, generalized motor incoordination, and partial paresis of the right arm that persisted over 2 yr. Magnetic resonance imaging early in the course of the disease demonstrated a localized left frontal lobe cerebritis. Larvae morphologically consistent with a Baylisascaris species were seen in tissue sections of the cerebrum and cerebellum. Epizootiologic investigation, which included qualitative fecal flotations, evaluation of soil samples for nematode eggs, and necropsy examination of livetrapped raccoons (Procyon lotor), indicated that Baylisascaris procyonis was most likely to have caused the cerebrospinal nematodiasis in this gibbon.

Trypanosoma cruzi infection of free-ranging lion-tailed macaques (Macaca silenus) and ring-tailed lemurs (Lemur catta) on St. Catherine's Island, Georgia, USA

Free-ranging Old World primates released on St. Catherine's Island, Georgia (USA), were tested for infection with Trypanosoma cruzi as part of a study of the epizootiology of sylvatic T. cruzi in the southeastern USA. The parasite was observed in liver infusion tryptose medium cultures of blood from seven of 11 lion-tailed macaques (Macaca silenus) and one of 19 ring-tailed lemurs (Lemur catta). Cultures of blood from 10 black and white ruffed lemurs (Varecia variegata) were all negative. Analysis of small subunit ribosomal RNA gene polymorphisms detected using polymerase chain reaction techniques indicates that the parasites isolated from both the lion-tailed macaques and the ring-tailed lemur are probably the same as T. cruzi parasites isolated from raccoons (Procyon lotor) trapped on St. Catherine's Island and other locations in the southeastern USA. Foraging lion-tailed macaques were observed to handle and partially consume specimens of Triatoma sanguisuga, the triatomine bug thought to be a vector of T. cruzi in the southeastern USA. Oral transmission of the parasite may have occurred as a result of this behavior.