Detection of Plasmodium in faeces of the New World primate Alouatta clamitans

Consistent detection of Trypanosoma brucei but not T. congolense DNA in faeces of experimentally infected cattle

Animal African trypanosomiasis (AAT) is a significant food security and economic burden in sub-Saharan Africa. Current AAT empirical and immunodiagnostic surveillance tools suffer from poor sensitivity and specificity, with blood sampling requiring animal restraint and trained personnel. Faecal sampling could increase sampling accessibility, scale, and species range. Therefore, this study assessed feasibility of detecting Trypanosoma DNA in the faeces of experimentally-infected cattle. Holstein-Friesian calves were inoculated with Trypanosoma brucei brucei AnTat 1.1 (n = 5) or T. congolense Savannah IL3000 (n = 6) in separate studies. Faecal and blood samples were collected concurrently over 10 weeks and screened using species-specific PCR and qPCR assays. T. brucei DNA was detected in 85% of post-inoculation (PI) faecal samples (n = 114/134) by qPCR and 50% by PCR between 4 and 66 days PI. However, T. congolense DNA was detected in just 3.4% (n = 5/145) of PI faecal samples by qPCR, and none by PCR. These results confirm the ability to consistently detect T. brucei DNA, but not T. congolense DNA, in infected cattle faeces. This disparity may derive from the differences in Trypanosoma species tissue distribution and/or extravasation. Therefore, whilst faeces are a promising substrate to screen for T. brucei infection, blood sampling is required to detect T. congolense in cattle.

Detection of Plasmodium falciparum in Saliva and Stool Samples from Children Living in Franceville, a Highly Endemic Region of Gabon

Due to the difficulty of obtaining blood samples, which is the invasive method that is currently used for the detection of Plasmodium spp., alternative diagnostic sampling methods that are effective and non-invasive are needed, particularly for long-term studies. Saliva and stool samples from malaria-infected individuals contain trace amounts of Plasmodium DNA and therefore could be used as alternatives. Malaria was screened using rapid diagnosis tests and confirmed via microscopy. Nested PCR tests targeting the Plasmodium falciparum-specific STEVOR gene were performed for blood, saliva and stool samples that were positive for malaria. Three hundred sixty-seven (367) children were enrolled and eighty (22.22%) were confirmed to be positive for malaria. Matched blood, saliva and stool samples were available for 35 children. By using blood smears as the gold standard for the diagnosis of malaria, our study indicates that Plasmodium DNA was more detectable in blood (100%) than in saliva (22.86%) and stools (14.29%). Applying qPCR to the STEVOR gene to detect Plasmodium falciparum DNA in saliva and stool samples cannot be considered as an alternative to the current malaria detection processes using blood specimens.

Prevalence of simian malaria among macaques in Malaysia (2000–2021): A systematic review

Background

The aim of Malaysia to eliminate malaria nationwide by 2020 seems need to be prolonged. Whilst Malaysia has successfully eliminated human malaria transmission, simian malaria parasites such as Plasmodium knowlesi, P. cynomolgi, P. inui and P. cynomolgi are the emerging cause of malaria in humans. The epidemiological study of simian malaria in primates provides useful information in identifying the risk of human-macaques Plasmodium infection.

Methodology/Principal findings

This study was performed to gather all available data in terms of simian malaria epidemiology study among macaques in Malaysia over the last two decades. This systematic review was conducted according to the PRISMA guidelines to select appropriate articles as references. Data searches were performed through international databases such as Google Scholar, PubMed, CrossRef, Scopus, Web of Science and Science Direct for original articles published from 2000 until 2021. The review identified seven simian malaria epidemiology studies in Malaysia over the 20-year study period. Most studies were conducted in Peninsular Malaysia (5/7; 71%) followed by East Malaysia (2/7; 29%). All studies showed positive detection of Plasmodium parasites in macaques. The most prevalent Plasmodium species in macaques was P. inui (49.27%) and the least prevalent was P. fieldi (4.76%). The prevalence of simian malaria was higher in East Malaysia compared to Peninsular Malaysia. The mono, dual and triple infection types were the most common among macaques.

Conclusion/Significance

The non-human primates like macaques are the reservoir of simian plasmodium in Malaysia. Hence, the study of host epidemiology is an important insight to public health management as there is a high occurrence of simian malaria in Malaysia. The right measurement can be taken as well to prevent the transmission of simian malaria from macaques to humans.

Macaques are the most abundant primates in south east Asia including Malaysia. Due to deforestation, macaques came closer to human settlements searching for food. Macaques like the long-tailed and pig-tailed harbouring several Plasmodium species that can cause zoonotic malaria in humans. Close contact of human and macaques cause zoonotic transmission of simian malaria. The simian plasmodium such as P. knowlesi, P. inui and P. cynomolgi have been found infecting humans in Malaysia; mainly in East Malaysia (Borneo). Zoonotic malaria poses great risk to public health as prolonged in treatment often lead to fatal outcomes. Hence the knowledge of prevalence and diversity is important to access, this can therefore enlighten the authorities to plan a control strategy that will minimize the zoonotic transmission between non-human primate host to human. This systematic review has summarised all publish data of macaques-plasmodium infection from the year 2000–2021 by using PRISMA guidelines. Our result showed that P. inui (49.27%) is the most prevalent Plasmodium species found in macaques, followed by P. cynomolgi (33.05%) and P. knowlesi (26.86%). Simian plasmodium prevalent was also found higher in East Malaysia (97.0%) compared to Peninsular Malaysia (45.18%). The significant increase of simian malaria incidences in human have jeopardized the national malaria elimination programme. Hence, this study provides a compact insight into the plasmodium epidemiology of macaques in Malaysia.

Exposure of Primate Reservoir Hosts to Mosquito Vectors in Malaysian Borneo

Several vector-borne pathogens of primates have potential for human spillover. An example is the simian malaria Plasmodium knowlesi which is now a major public health problem in Malaysia. Characterization of exposure to mosquito vectors is essential for assessment of the force of infection within wild simian populations, however few methods exist to do so. Here we demonstrate the use of thermal imaging and mosquito magnet independence traps (MMIT) to assess the abundance, diversity and infection rates in mosquitoes host seeking near long-tailed macaque (Macaca fasicularis) sleeping sites in the Lower Kinabatangan Wildlife Sanctuary, Malaysian Borneo. The primary Plasmodium knowlesi vector, Anopheles balabacensis, was trapped at higher abundance near sleeping sites than control trees. Although none of the An. balabacensis collected (n = 15) were positive for P. knowlesi by PCR screening, two were infected with another simian malaria Plasmodium inui. Analysis of macaque stools from sleeping sites confirmed a high prevalence of Plasmodium infection, suspected to be P. inui. Recently, natural transmission of P. inui has been detected in humans and An. cracens in Peninsular Malaysia. The presence of P. inui in An. balabacensis here and previously in human-biting collections highlight its potential for spillover from macaques to humans in Sabah. We advocate the use of MMITs for non-invasive sampling of mosquito vectors that host seek on wild simian populations.

Evolutionary history of Plasmodium vivax and Plasmodium simium in the Americas

Malaria is a vector-borne disease caused by protozoan parasites of the genus Plasmodium. Plasmodium vivax is the most prevalent human-infecting species in the Americas. However, the origins of this parasite in this continent are still debated. Similarly, it is now accepted that the existence of Plasmodium simium is explained by a P. vivax transfer from humans to monkey in America. However, many uncertainties still exist concerning the origin of the transfer and whether several transfers occurred. In this review, the most recent studies that addressed these questions using genetic and genomic approaches are presented.

Molecular Detection and Characterization of Intestinal and Blood Parasites in Wild Chimpanzees (Pan troglodytes verus) in Senegal

Simple Summary

Western chimpanzees are currently listed as a Critically Endangered subspecies. Human encroachment has taken a toll on this great ape due to fragmented habitat and the exchange of pathogens. This epidemiological study investigated the occurrence and genetic diversity of intestinal and blood parasites in faecal samples from wild chimpanzees living in the Dindefelo Community Nature Reserve, Senegal. We paid special attention to potential human-driven sources of infection and transmission pathways. Potential diarrhoea-causing protist parasites (e.g., Cryptosporidium spp., Giardia duodenalis, Entamoeba histolytica) were detected at low infection rates (and densities) or absent, whereas commensals (Entamoeba dispar) or protist of uncertain pathogenicity (Blastocystis sp.) were far more abundant. We detected Sarcocystis spp. in chimpanzee faeces. Blood protist parasites such as Plasmodium spp. and Trypanosoma brucei spp. (the etiological agents of malaria and sleeping sickness, respectively, in humans) were also found at low prevalences, but microfilariae of the nematode Mansonella perstans were frequently found. Molecular analyses primarily revealed host-adapted species/genotypes and an apparent absence of gastrointestinal clinical manifestations in infected chimpanzees. Zoonotic events of still unknown frequency and directionality may have taken part between wild chimpanzees and humans sharing natural habitats and resources.

Abstract

Wild chimpanzee populations in West Africa (Pan troglodytes verus) have dramatically decreased as a direct consequence of anthropogenic activities and infectious diseases. Little information is currently available on the epidemiology, pathogenic significance, and zoonotic potential of protist species in wild chimpanzees. This study investigates the occurrence and genetic diversity of intestinal and blood protists as well as filariae in faecal samples (n = 234) from wild chimpanzees in the Dindefelo Community Nature Reserve, Senegal. PCR-based results revealed the presence of intestinal potential pathogens (Sarcocystis spp.: 11.5%; Giardia duodenalis: 2.1%; Cryptosporidium hominis: 0.9%), protist of uncertain pathogenicity (Blastocystis sp.: 5.6%), and commensal species (Entamoeba dispar: 18.4%; Troglodytella abrassarti: 5.6%). Entamoeba histolytica, Enterocytozoon bieneusi, and Balantioides coli were undetected. Blood protists including Plasmodium malariae (0.4%), Trypanosoma brucei (1.3%), and Mansonella perstans (9.8%) were also identified. Sanger sequencing analyses revealed host-adapted genetic variants within Blastocystis, but other parasitic pathogens (C. hominis, P. malariae, T. brucei, M. perstans) have zoonotic potential, suggesting that cross-species transmission between wild chimpanzees and humans is possible in areas where both species overlap. Additionally, we explored potential interactions between intestinal/blood protist species and seasonality and climate variables. Chimpanzees seem to play a more complex role on the epidemiology of pathogenic and commensal protist and nematode species than initially anticipated.

Zoonotic Blood-Borne Pathogens in Non-Human Primates in the Neotropical Region: A Systematic Review

Background: Understanding which non-human primates (NHPs) act as a wild reservoir for blood-borne pathogens will allow us to better understand the ecology of diseases and the role of NHPs in the emergence of human diseases in Ecuador, a small country in South America that lacks information on most of these pathogens. Methods and principal findings: A systematic review was carried out using PRISMA guidelines from 1927 until 2019 about blood-borne pathogens present in NHPs of the Neotropical region (i.e., South America and Middle America). Results: A total of 127 publications were found in several databases. We found in 25 genera (132 species) of NHPs a total of 56 blood-borne pathogens in 197 records where Protozoa has the highest number of records in neotropical NHPs (n = 128) compared to bacteria (n = 12) and viruses (n = 57). Plasmodium brasilianum and Trypanosoma cruzi are the most recorded protozoa in NHP. The neotropical primate genus with the highest number of blood-borne pathogens recorded is Alouatta sp. (n = 32). The use of non-invasive samples for neotropical NHPs remains poor in a group where several species are endangered or threatened. A combination of serological and molecular techniques is common when detecting blood-borne pathogens. Socioecological and ecological risk factors facilitate the transmission of these parasites. Finally, a large number of countries remain unsurveyed, such as Ecuador, which can be of public health importance. Conclusions and significance: NHPs are potential reservoirs of a large number of blood-borne pathogens. In Ecuador, research activities should be focused on bacteria and viruses, where there is a gap of information for neotropical NHPs, in order to implement surveillance programs with regular and effective monitoring protocols adapted to NHPs.

Molecular Identification of Plasmodium falciparum from Captive Non-Human Primates in the Western Amazon Ecuador

Background: Malaria is a disease caused by hemoparasites of the Plasmodium genus. Non-human primates (NHP) are hosts of Plasmodium sp. around the world. Several studies have demonstrated that Plasmodium sp. emerged from Africa. However, little information is currently available about Plasmodium falciparum in the neotropical NHP and even less in Ecuador. Indeed, the objective of our study was to identify by molecular phylogenetic analyses the Plasmodium species associated with NHP from the Western Amazon region of Ecuador, and to design a molecular taxonomy protocol to use in the NHP disease ecology. Methods: We extracted DNA from faecal samples (n = 26) from nine species of captive (n = 19) and free-ranging (n = 7) NHP, collected from 2011 to 2019 in the Western Amazon region of Ecuador. Results: Using a pan-Plasmodium PCR, we obtained one positive sample from an adult female Leontocebus lagonotus. A maximum likelihood phylogenetic analysis showed that this sequence unequivocally clustered with Plasmodium falciparum. Conclusions: The identification of Plasmodium sp. in NHP of the Ecuadorian Amazon would be essential to identify their role as potential zoonotic reservoirs, and it is also important to identify their origin in wildlife and their transmission in captive NHP.

Atlantic Forest Malaria: A Review of More than 20 Years of Epidemiological Investigation

In the south and southeast regions of Brazil, cases of malaria occur outside the endemic Amazon region near the Atlantic Forest in some coastal states, where Plasmodium vivax is the recognized parasite. Characteristics of cases and vectors, especially Anopheles (Kerteszia) cruzii, raise the hypothesis of a zoonosis with simians as reservoirs. The present review aims to report on investigations of the disease over a 23-year period. Two main sources have provided epidemiological data: the behavior of Anopheles vectors and the genetic and immunological aspects of Plasmodium spp. obtained from humans, Alouatta simians, and Anopheles spp. mosquitoes. Anopheles (K.) cruzii is the most captured species in the forest canopy and is the recognized vector. The similarity between P. vivax and Plasmodium simium and that between Plasmodium malariae and Plasmodium brasilianum shared between simian and human hosts and the involvement of the same vector in the transmission to both hosts suggest interspecies transfer of the parasites. Finally, recent evidence points to the presence of Plasmodium falciparum in a silent cycle, detected only by molecular methods in asymptomatic individuals and An. (K.) cruzii. In the context of malaria elimination, it is paramount to assemble data about transmission in such non-endemic low-incidence areas.

Naturally Acquired Humoral Immunity against Malaria Parasites in Non-Human Primates from the Brazilian Amazon, Cerrado and Atlantic Forest

Non-human primates (NHPs) have been shown to be infected by parasites of the genus Plasmodium, the etiological agent of malaria in humans, creating potential risks of zoonotic transmission. Plasmodium brasilianum, a parasite species similar to P. malariae of humans, have been described in NHPs from Central and South America, including Brazil. The merozoite surface protein 1 (MSP1), besides being a malaria vaccine candidate, is highly immunogenic. Due to such properties, we tested this protein for the diagnosis of parasite infection. We used recombinant proteins of P. malariae MSP1, as well as of P. falciparum and P. vivax, for the detection of antibodies anti-MSP1 of these parasite species, in the sera of NHPs collected in different regions of Brazil. About 40% of the NHP sera were confirmed as reactive to the proteins of one or more parasite species. A relatively higher number of reactive sera was found in animals from the Atlantic Forest than those from the Amazon region, possibly reflecting the former more intense parasite circulation among NHPs due to their proximity to humans at a higher populational density. The presence of Plasmodium positive NHPs in the surveyed areas, being therefore potential parasite reservoirs, needs to be considered in any malaria surveillance program.

Optimizing a Noninvasive Oral Sampling Technique for Semicaptive Neotropical Primates in Peru

Disease surveillance in Neotropical primates (NP) is limited by the difficulties associated with anesthetizing NP for sample collection in remote settings. Our objective was to optimize a noninvasive method of oral sampling from semicaptive NP in Peru. We offered 40 NP at Taricaya Rescue Centre in Madre de Dios, Peru ropes coated in various attractants and measured variables (acceptance of the rope, chewing time, and volume of fluid eluted from ropes) that may affect sample acquisition and quality. We preserved samples by direct freezing in liquid nitrogen or by storing samples in RNA stabilization reagent at room temperature. Sample integrity was measured by testing for mammalian cytochrome b with the use of conventional PCR. The NP successfully chewed on a rope in 82% (125/152) of trials. Overall sample integrity was high, with 96% (44/46) of samples (both directly frozen and stored in stabilization reagent) testing positive for cytochrome b. The number of times that an individual NP was exposed to the rope procedure and NP age were associated with higher acceptance rates and the NP successfully chewing on the rope. We conclude that ropes serve as a feasible noninvasive method of obtaining oral samples from NP at rescue centers and could be used in future studies to evaluate population genetics and for pathogen surveillance for population health monitoring.

Prevalence of Plasmodium parasites in non-human primates and mosquitoes in areas with different degrees of fragmentation in Colombia

BACKGROUND

Parasites from the genus Plasmodium, the aetiological agent of malaria in humans, can also infect non-human primates (NHP), increasing the potential risk of zoonotic transmission with its associated global public health concerns. In Colombia, there are no recent studies on Plasmodium spp. infecting free-ranging NHP. Thus, this study aimed to determine the diversity of Plasmodium species circulating in fragmented forests in central Colombia, both in Anopheles mosquitoes and in the four sympatric NHP in the region (Ateles hybridus, Cebus versicolor, Alouatta seniculus and Aotus griseimembra), in order to evaluate the risk of infection to humans associated with the presence of sylvatic hosts and vectors infected with Plasmodium spp.

METHODS

Overall, there were collected 166 fecal samples and 25 blood samples from NHP, and 442 individuals of Anopheles spp. DNA extraction, nested PCR using mitochondrial (cox3 gene) and ribosomal (18S rDNA) primers, electrophoresis and sequencing were conducted in order to identify Plasmodium spp. from the samples.

RESULTS

Plasmodium falciparum was detected in two fecal samples of Alouatta seniculus, while Plasmodium vivax/simium infected Ateles hybridus, Cebus versicolor and Alouatta seniculus. Co-infections with P. vivax/simium and Plasmodium malariae/brasilianum were found in three individuals. The highest prevalence from blood samples was found for Plasmodium malariae/brasilianum in two Alouatta seniculus while Plasmodium vivax/simium was most prevalent in fecal samples, infecting four individuals of Alouatta seniculus. Seven Anopheles species were identified in the study site: Anopheles (Anopheles) punctimacula, Anopheles (An.) malefactor, Anopheles (Nyssorhynchus) oswaldoi, Anopheles (Nys.) triannulatus, Anopheles (An.) neomaculipalpus, Anopheles (Nys.) braziliensis and Anopheles (Nys.) nuneztovari. Infection with P. vivax/simium was found in An. nuneztovari, An. neomaculipalpus, and An. triannulatus. Furthermore, An. oswaldoi and An. triannulatus were found infected with P. malariae/brasilianum. The effect of fragmentation and distance to the nearest town measured in five forests with different degrees of fragmentation was not statistically significant on the prevalence of Plasmodium in NHP, but forest fragmentation did have an effect on the Minimum Infection Rate (MIR) in Anopheles mosquitoes.

CONCLUSIONS

The presence of Plasmodium spp. in NHP and Anopheles spp. in fragmented forests in Colombia has important epidemiological implications in the human-NHP interface and the associated risk of malaria transmission.