Acta Tropica 235 (2022) 106670 Contents lists available at ScienceDirect Acta Tropica journal homepage: www.elsevier.com/locate/actatropica Environmental predictors of filarial infection in Amazonian primates Ecological factors and primate filarial infection David F. Conga a, Hani R. El Bizri b, c, d, e, Carlos González Crespo f, Luis A. Gomez-Puerta g, Gabriela M. Ulloa-Urizar a, h, Pedro E. Pérez-Peña i, Mark Bowler j, k, l, Pedro Mayor a, d, m, n, * a Programa de Pós-Graduação em Saúde e Produção Animal na Amazônia, Universidade Federal Rural da Amazônia (UFRA), Av. Presidente Tancredo Neves 2501, Terra Firme, Belém-Pará 66077-830, Brazil b Grupo de Pesquisa em Ecologia de Vertebrados Terrestres, Instituto de Desenvolvimento Sustentável Mamirauá (IDSM), Estrada do Bexiga 2584, Fonte Boa, Tefé- Amazonas 69553-225, Brazil c Department of Natural Sciences, Manchester Metropolitan University, Oxford Road, Manchester M15 6BH, United Kingdom d Comunidad de Manejo de Fauna Silvestre en la Amazonía y en Latinoamérica (COMFAUNA), 332 Malecon Tarapaca, Iquitos, Peru e Rede de Pesquisa sobre Diversidade, Conservação e Uso da Fauna na Amazônia (RedeFauna), Manaus, Amazonas, Brazil f Center for Animal Disease Modeling and Surveillance, Department of Medicine and Epidemiology, University of California, Davis, Davis, CA, United States g Department of Veterinary Epidemiology and Economics, School of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru h Laboratorio de Microbiología y Genómica Bacteriana, Universidad Científica del Sur, Lima, Peru i Instituto de Investigaciones de la Amazonía Peruana, Av. Jose A. Quiñones km 2.5, Loreto, Iquitos, Peru j School of Engineering, Arts, Science and Technology Science, University of Suffolk, Waterfront Building, Neptune Quay, Ipswich IP4 1QJ, United Kingdom k Institute for Conservation Research, San Diego Zoo Global, Escondido, California, CA 92027-9614, United States l Suffolk Sustainability Institute, Waterfront Building, Neptune Quay, Ipswich IP4 1QJ, United Kingdom m Departament de Sanitat i d’Anatomia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Edifici V, Bellaterra-Barcelona E-08193, Spain n Museo de Culturas Indígenas Amazónicas, Loreto, Iquitos, Peru A R T I C L E I N F O A B S T R A C T Keywords: Filarial nematode infections are common in primates, but have received little attention in the Neotropics. Amazon Epidemiological data on filarial infections in primates are still too sparse to fully understand the complex of this Dipetalonema parasitism, especially because of the difficulty in studying the ecology and epidemiology of wild primates.. We Eco-epidemiology describe natural infections by Dipetalonema parasitizing 211 primates belonging to eight free-living primate Filariae Neotropical primates genera in Amazonia, and assess the relationships between parasitic indicators and climatic (rainfall and river level), ecological (fruiting periods of plants) and biological (sex, species’ body mass, group size and density) factors. The overall prevalence was 64.4% (95% CI: 64.0 – 64.9); parasitic mean abundance (N filariae per in­ dividual) and parasitic mean intensity (N filariae per infected host) of infection were 11.9 (95% CI: 8.3 – 15.6) and 18.4 (95% CI: 13.4 – 23.4) filariae/individual, respectively. Although we observed differences in parasitic parameters among primate genera, there was no correlation between parasitic parameters with density, body mass or group size. Sapajus, Cebus and Lagothrix had the highest prevalence and parasitic mean intensity. Using Lagothrix lagotricha poeppigii, the most sampled species (n = 92), as a model, we found that the number of filariae per infected host was associated with fruit production in swamp forests during the dry season, the time of food scarcity. The long periods of food shortage may cause environmental stress on primates, impairing their immune defenses and leading to increased parasite load but not affecting infection prevalence. However, the lack of information on vector ecology, key to understand risk factors associated to infection rate, prevents confirming the existence of an infection pattern dependent on food availability. * Corresponding author at: Departament de Sanitat i d’Anatomia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Edifici V, Bellaterra- Barcelona E-08193, Spain. E-mail addresses: mayorpedro@hotmail.com, pedrogines.mayor@uab.cat (P. Mayor). https://doi.org/10.1016/j.actatropica.2022.106670 Received 16 February 2022; Received in revised form 30 July 2022; Accepted 25 August 2022 Available online 28 August 2022 0001-706X/© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). D.F. Conga et al. Acta Tropica 235 (2022) 106670 1. Introduction 2.3. Parasitic indicators Human filariasis, particularly that caused by Mansonella ozzardi For the calculation of parasitic parameters, we considered the Dipe­ (Beltrán et al., 2008), is a frequent but neglected disease in Amazonia talonema genus, which was observed in all infected NHPs. Parasitic in­ (Medeiros et al., 2009; Herrera et al., 2013). Clinical manifestation in dicators for each host species, and for all primates pooled were human filariasis depends on the filarial species and infected organ, but calculated according to Bush et al. (1998). Indicators were: prevalence frequently includes skin and ophthalmic lesions, joint pain, headache, (percentage of hosts with filariae), parasitic mean abundance (PMA, and lymphadenopathy (Branco et al., 1998; Adami and Herzos, 2008). number of parasites divided by the number of infected and uninfected Filarial nematode infections from the genera Dipetalonema and Man­ hosts, expressed as number of filariae per host), parasitic mean intensity sonella (Tetrapetalonema) have long been detected in wild non-human (PMI, number of parasites divided by the number of infected hosts, primates (NHP) in Neotropical forests (Eberhard et al., 1984; Bain expressed as number of filariae per infected host), and amplitude range et al., 1986), and recently, high prevalence of filariasis has been recor­ (AR, minimum and maximum number of parasites in a sample). ded in free-living NHPs in the northeastern Peruvian Amazon (Conga et al., 2018a, 2018b) and in northeastern Argentina (Vanderhoeven 2.4. Biological variables of hosts et al., 2017). Epidemiological data on filariasis in both humans and wild NHP are Biological variables included the sex and female reproductive state scarce, largely because of the difficulty in obtaining biological and (pregnant/non-pregnant) of each primate specimen, and the average epidemiological samples. Thus, integrative ecological studies on para­ body mass, average group size, and density of each species (Table 1). sites, hosts and their habitats are required to understand the dynamics of The sex and female reproductive state were determined through exam­ human infections. Filariasis infection depends on the presence of vec­ inations of the genitalia in each hunted specimen. We considered fe­ tors; hematophagous arthropods from the Ceratopogonidae and Simu­ males with at least one embryo or fetus to be pregnant, and females liidae families, whose populations are in turn determined by seasonal without embryo or fetus as non-pregnant. Since we could not obtain the climatic factors, such as rainfall and river level (Medeiros and Py-Da­ body mass of each individual, we used the average body mass for each niel, 2004). In addition, the reproductive status and the food availabil­ NHP species obtained from the available literature (Emmons and Feer, ity, often driven by climatic seasonality, may also influence the intensity 1990; Hershkovitz, 1990; Ford, 1994; Smith and Jungers, 1997; Lu, of parasitic infection due to hormonal changes and the nutritional status 1999; Jack, 2007). of hosts (Klein, 2004). We estimated the density (individuals/km2) and the average group In this study, we determined parasitic indicators of filariasis in eight size (individuals/group) of each NHP species only in the Yavari-Mirin NHP genera from the Peruvian Amazon, and described the relationship River from direct sightings conducted on twelve 4-km wide transects between infection rates and ecological (percentage of trees bearing monitored from 2008 to 2012, with a total of 1173.5 km survey effort in fruits), biological (density, group size and body mass) and climatic upland and flooded forests. Transects were opened prior to the surveys factors (rainfall and river water level). and researchers and local residents walked each one multiple times. Two observers (a technician and a local resident, or two local residents) 2. Material and methods walked the trails between 6:00 h and 15:00 h at an average speed of 1.5 km/h. When a group of NHP was encountered, the number of in­ 2.1. Study area dividuals was recorded, and the perpendicular distance from the trail to the first individual sighted was measured with a measuring tape. We The study area covers three geographic sites in the Loreto region, sighted 1336 groups of the NHP, totaling 10,543 individuals. Distance northeast of the Peruvian Amazon, in the Yavari-Mirin, Corrientes and 7.1 software was used to estimate population density (number of in­ Pastaza River Basins. These areas are inhabited by remote rural com­ dividuals/km2) of each NHPs species (Peres, 1999; Buckland et al., munities relying on agriculture, fisheries and subsistence hunting. The 2001). climate in the region is typically equatorial with annual temperatures varying between 22 ◦ C to 36 ◦ C, relative humidity of 80% and annual rainfall between 1500 and 3000 mm3. 2.5. Climatic and plant phenological variables 2.2. Collected samples and obtaining of filariae specimens Climatic and plant phenological variables were only collected in the study area of the Yavari-Mirin River basin. Information on river water We sampled primate specimens between 2009 and 2015 as part of a level (in meters above sea level, m.a.s.l.) and rainfall (in mm3) in each participatory conservation program that involves local subsistence month-year was obtained from the Yavari River hydrological station, hunters in implementing community wildlife management in the com­ about 50 km from the study area and monitored by National Water munities of Corrientes (José Olaya, Jerusalén), Pastaza (Andoas, Andoas Agency of Brazil (HidroWeb, Estirão do Repouso Station, http://www.sni Viejo, Titiyacu, Los Jardines) and the Yavari-Mirin River Basin (Nueva rh.gov.br/hidroweb/). Esperanza). Local hunters were trained to record the date, species, and To determine annual changes in ripe fruit availability in the Yavari- gender of all animals of all taxa hunted during their normal subsistence Mirin River basin, three transects were established from random starting activities. Hunters were also trained to handle hunted animals hygien­ points in upland forests and palm-dominated swamps, which were ically and to remove the entire abdominal and thoracic organs from sampled for one year (2004). All sections were 5 m wide, except one in specimens and to store them in a 4% formaldehyde fixative solution. The upland forest, which was 20 m wide (Pitman et al., 2003). We marked procedure was performed for various groups of mammals and birds, not and identified all trees with diameter at breast height (DBH) >10 cm as only for wild NHP, avoiding inducing NHP hunting. Hence, no addi­ well as all lianas with DBH > 7 cm (following Ayres, 1986). Plants were tional mortality for the purpose of this study was caused. Adult filariae sampled until the rate of new species discovery decreased (Sutherland, located in the abdominal and thoracic cavities and adhered to the 2000), determining the length and area of transects in each forest type. external surface of the organs were removed, washed in saline solution, Five hundred and eighty-nine trees and lianas were sampled in 8970 m2 preserved in 70% ethanol, and identified using the taxonomic keys of dryland forests and 386 trees and lianas in 5150 m2 in palm swamps. available in Bain et al. (1986) and Bain et al. (1987). In the middle of each month, we observed the canopy of each marked tree and liana with binoculars, recording the presence or absence of ripe fruits in each individual sampled. 2 D.F. Conga et al. Acta Tropica 235 (2022) 106670 Table 1 Parasitic mean intensity (PMI, N filarid by infected host), amplitude range (AR, N minimum and maximum filarid per infected host and median of PMI), parasitic mean abundance (PMA, N of filarid by host) and prevalence (%) of infection by three species of filariae in free-living non-human primates (n = 211) in all study areas, the Yavari-Mirin, Corrientes and Pastaza River Basins. Different letters within columns indicate significant differences at P ≤ 0.05. Species Prevalence (%) PMI AR (median) PMA D. gracile D. caudispina D. freitasi Total% Saimiri spp. 100 (04/04) 0 (0/04) 0 (0/04) 100 (04/04)abc 27 ± 23.2ab 9–60 (19.5) 27.0 ± 23.2 Ateles spp. 75 (03/04) 75 (03/04) 0 (0/04) 100 (04/04)abc 11.5 ± 11.8ab 4–29 (7.0) 11.5 ± 11.8 Cebus spp. 90 (09/10) 30 (03/10) 0 (0/10) 90 (09/10)ab 28.9 ± 39.9a 1–124 (12.0) 26.0 ± 38.7 Lagothrix spp. 73 (76/104) 1 (01/104) 0 (0/104) 74 (77/104)a 21.6 ± 21.3a 1–108 (16.0) 15.9 ± 20.6 Sapajus spp. 65 (32/49) 14 (07/49) 0 (0/49) 65 (32/49)ab 10.9 ± 13.4ab 1–61 (6.5) 7.1 ± 12.3 Cacajao spp. 0 (0/12) 0 (0/12) 50 (06/12) 50 (06/12)ab 9 ± 10.6ab 1–24 (3.5) 4.5 ± 8.5 Alouatta spp. 20 (02/10) 0 (0/10) 0 (0/10) 20 (02/10)b 9 ± 5.7ab 5–13 (9.0) 1.8 ± 4.2 Pithecia spp. 11 (02/18) 0 (0/18) 0 (0/18) 11.1 (02/18)c 3.5 ± 2.1b 2–5 (3.5) 0.39 ± 1.2 Total 61 (128/211) 7 (14/211) 3 (06/211) 64.4 (136/211) 18.4 1–124 (12.0) 11.9 2.6. Statistical analysis sampled, 114 (57.3%) were male and 85 (42.7%) were female (70 non- pregnant and 15 pregnant females). In 12 individuals the genital organs We used generalized linear models (GLM) and Classification and were not collected and therefore we do not have sex information. From Regression Tree models (CART) to evaluate the influence of biological these hosts, 2502 adult filariae belonging to three species were obtained, and environmental variables on parasitic indicators: parasitic preva­ parasitizing the abdominal and thoracic cavities: Dipetalonema gracile lence (binomial distribution) and PMI (number of filariae per infected (Rudolphi, 1809), Dipetalonema caudispina (Molin, 1858) and Dipetalo­ host, Poisson distribution). Depending on the availability of sufficient nema freitasi (Bain et al., 1987). sample size, and the sources of the ecological, phenological and climatic Firstly, we compared parasitic prevalence and intensity between information two statistical designs (biological and environmental) were genera, sexes, female reproductive status and study area for all NHP conducted for both parasitic prevalence and intensity of infection. hosts evaluated in the Pastaza, Corrientes and Yavari-Mirin River basins. Firstly, in the biological statistical design we tested the biological The total prevalence of filariasis of Dipetalonema spp. was 64.5% (136/ variables (host genera, sex, body mass, group size, population density 211) (95% CI: 64.0 – 64.9) in all NHPs examined. Table 2 shows all and study area), for all primates sampled in the Pastaza, Corrientes and parasitic indicators for the 211 NHP evaluated in the eight host genera Yavari-Mirin River basins. Secondly, in the environmental statistical evaluated in the three study areas. Of all sampled specimens, 35.5% (75/ design, we evaluated the environmental variables (monthly rainfall, 211) were non-infected, 29.9% (63/211) were lightly infected (1–10 monthly number of rainy days, monthly river water level, and per­ filariae per host), 31.3% (66/211) moderately infected (11–60 filariae centage of trees bearing fruits both in upland and swamp forests) using per host), and 3.3% (7/211) were heavily infected (>60 filariae per Lagothrix lagothrica poeppigii in the Yavari-Mirin River basin as our host). model species, due to higher number of samples (n = 92). We found a prevalence of 66.1% (125/189) for the Yavari-Mirin In the GLM’s analyses (R package stats, version 3.6.2), we first tested River basin, 57.1% (4/7) for the Corrientes River basin, and 46.7% the best family of distribution for the analyses, comparing these based (7/15) for the Pastaza River basin; and PMI was 11.4 ± 19.6, 9.5 ± 7.0, on QQ-plots of the residuals, and on the Akaike Information Criteria and 51.0 ± 23.1 filariae per host, respectively. Prevalence was 64.0% (AIC). Secondly, we tested for collinearity using the variance inflation (73/114) for males and 69.4% (59/85) for females, and PMI was 17.8 ± factor (VIF, Marquardt, 1970), which measures how strongly each pre­ 21.4 specimens per host for males and 19.5 ± 21.6 for females. Pregnant dictor can be explained by the rest of predictors. A VIF = 5 was set as a females had a prevalence of 75.0% (9/12), PMI of 15.8 ± 18.3, and PMA threshold to remove any variable from the model as signal of collinearity of 11.8 ± 17.2 specimens per pregnant female; while in non-pregnant problems. We calculated VIF for all predictors and monthly rainfall (VIF: females, prevalence was 68.5% (50/73), with PMI of 20.2 ± 22.2, and 5.499), was excluded from the environmental statistical design. Then, to PMA of 13.8 ± 20.6 specimens per female. select the best combination of predictor variables, we built a model Saimiri, Ateles and Cebus showed the highest prevalence (100%, where all the predictor variables were included and used the stepwise 100% and 90%, respectively), while Cebus, Saimiri and Lagothrix pre­ function (R package stats, version 3.6.2). The final model, in terms of sented the highest mean PMI (28.9, 27.0 and 21.6 filariae per infected retention of predictor variables, was defined based on AIC values host, respectively) and PMA (26.0, 27.0 and 15.9 filariae per total host (Burnham and Anderson, 2004), in which the model with the lowest AIC analyzed, respectively). In the biological statistical design, significant was selected. The final model was also executed as a CART model (R differences were observed in the parasitic prevalence (GLM, AIC = package rpart, version 4.1–15, Therneau et al., 2013). 218.9) among the host genera (P = 4.215e-07). Based on parasitic Descriptive statistics were expressed as mean ± standard deviation (SD). All statistical analyses were performed using the software R 4.0.5 Table 2 (R Core Team, 2021), and statistics with a probability value of 0.05 or Body mass (in kg), group size (in individuals/group), density (in individuals lower (P ≤ 0.05) were considered significant. /km2) of the eight free-living non-human primate species (n = 189) in the Yavari-Mirin River Basin. 3. Results Body mass (kg) Group size Density (ind/group) (ind/km2) During the study period, 211 NHPs were sampled, including 104 Alouatta seniculus 6.1 4.08 1.27 wooly monkeys Lagothrix spp. (L. l. poeppigii), 49 large-headed capuchins Ateles chamek 8.8 4.51 3.45 Sapajus spp. (S. macrocephalus), 18 monk saki monkeys Pithecia spp. Cacajao calvus 3.2 26.47 5.57 (P. monachus and P. aequatorialis), 12 red uakari monkeys Cacajao spp. Cebus albifrons 2.9 5.96 4.04 Lagothrix l. poeppiggii 7.1 9.72 45.81 (Cacajao calvus ucayalii), 10 red howler monkeys Alouatta spp. Pithecia monachus 2.4 3.4 9.12 (A. seniculus), 10 white-fronted capuchins Cebus spp. (C. unicolor and Saimiri macrodon 0.7 15.21 22.54 C. yuracus), four squirrel monkeys Saimiri spp. (S. macrodon) and four Sapajus macrocephalus 3 5.673 9.19 spider monkeys Ateles spp. (A. chamek and A. belzebuth). Of all NHP 3 D.F. Conga et al. Acta Tropica 235 (2022) 106670 prevalence, the CART model (R2 = 28.57%) classified the host genera selected the percentage of trees bearing fruits in swamps forests as the into two clusters, with lower prevalence (14.28% of being positive) in most important variable, with the value 0.5% as threshold dividing the Alouatta and Pithecia; and higher prevalence in Ateles, Cacajao, Cebus, PMI into two clusters (< 0.5% with 41 filariae per infected host, Lagothrix, Saimiri and Sapajus (73.59% of being positive). Significant covering the months of September and October, Fig. 2). When the per­ differences were also observed in PMI (GLM, AIC = 2515.32) among the centage of trees bearing fruits in swamps forests is > 0.5%, the monthly NHP genera (P < 2e-16), and the study area (P < 2e-16). The host genera river water level divides the PMI in three clusters (monthly river water ≥ were firstly selected in the CART model (R2 = 16.95%, Fig. 1A) and 1.5 m with 13 filariae per infected host; <1.2 m with 15 filariae per divided into two clusters based on PMI; Alouatta, Ateles, Cacajao, Pithecia infected host; and between 1.2 and 1.5 m with 24 filariae per infected and Sapajus had on average 1.87 filariae per infected host, and Cebus, host). Lagothrix and Saimiri had 2.70 filariae per infected host. The CART model also found differences within Cebus, Lagothrix and Saimiri hosts in 4. Discussion relation to the study area; primates from the Pastaza River had more filariae in comparison with those from Corrientes and Yavari-Mirin Parasitological studies in natural environments are essential to the (3.46 versus 2.64 average number of filariae per infected host, respec­ understanding of ecological and biological factors that influence the tively). Sex, body mass, group size and population density had no sig­ complexities of transmission and parasite infection in free-living NHP, nificant effect on the parasitic indicators. and the relevance of these to infection risk in humans. However, In the environmental statistical design, no significant difference was ecological information on parasites in wild animals is difficult to obtain. observed in the parasitic prevalence (GLM, AIC = 94.79). However, As part of a participatory conservation program involving local significant differences were found in PMI (GLM, AIC = 1154.28) related Amazonian hunters, it was possible to retrieve adult filariae from eight to the percentage of trees bearing fruits in swamps forests (Estimate = free-living NHP genera. Studies on the prevalence of filarial infection in − 0.0871, P < 1.19e-09) and monthly river water level (Estimate = wild primates are scarce. To our knowledge, only one has been done − 0.2575, P = 0.00238). The GLM results showed that each 1% increase previously, using molecular techniques to detect filarial infection in of trees bearing fruits in swamps forests and 1 m increase in monthly African primates (Gaillard et al., 2020), and they found a prevalence of river water level reduced the number of filariae per infected host by a 38%, lower than the 64% we report at our Amazonian site. Our results factor of 0.916 (8.3%) and 0.773 (23%), respectively. The CART model offer a first point of reference for filarial infections in Neotropical pri­ with higher proportion of the variance explained (R2 = 20.77%, Fig. 1B) mates, and the participatory methods we used may be a model for the development of further research on filariae indicators in wild mammals in other tropical areas. Our results show differences between NHP genera studied, with higher parasite prevalence and intensity of the infection in Cebus, Lagothrix and Saimiri compared to Alouatta and Pithecia. Recent studies on wild primates indicate that climate and ecological factors have greater effects on parasitism than host physiology (Martí­ nez-Mota et al., 2017). Climatic factors strongly affect vector density, behavior and susceptibility to parasites (Famakinde, 2018). Amazonian rainforests undergo significant seasonal changes during the year, easily measurable through rainfall and river water levels (Endo et al., 2016), that result in seasonal variation in fruit production and maturation (Haugaasen and Peres, 2005) and increases in vector populations during the rainy season, often resulting in increased cases of disease (Kuhn et al., 2005). Our study showed the influence of environmental variables on the parasitic intensity; lower percentage of trees bearing ripe fruits led to higher numbers of parasites per infected host. During the dry months in the Amazon rainforest, there is a shortage of food for frugivores. This lean period may be temporally alleviated by the fruiting of Mauritia flexuosa in swamp-forests (Storti, 1993), the main food consumed by Cacajao calvus ucayalii and other primates during these periods (Bowler and Bodmer, 2011), which is seasonal and dependent on edapho-climatic conditions, usually occurring from the end of the rainy season and occasionally extending throughout the dry season. However, the long-term food shortages during the dry period may cause envi­ ronmental stress in primates, leading to impaired body condition (Ste­ venson et al., 2000; Dew, 2005) and decreased immune response against parasitic, viral, and bacterial infections (Muehlenbein, 2006; Web­ ster-Marketon and Glaser, 2008). Impairment of immune defenses that modulate the degree of parasite-host balance may be involved in the increased parasite load, but not necessarily in the prevalence of infection. In our study, the water level is a secondary driver to explain the filariae intensity. When there was no food shortage, intermediate river Fig. 1. CART model results of the influence of A) hosts genera (Alouatta, Alt; Ateles, Atl; Cacajao, Ccj; Cebus; Lagothrix; Phitecia, Pth; Saimiri; and Sapajus, Spj; water levels were related to higher intensity of infection. The rainy and study areas (Corrientes, Crr; Yavarí-Mirin, Y-M; Pastaza) in the parasitic season favors mosquito populations, through the increased survival of intensity (number of filariae per infected host), and B) percentage of trees larvae and life span of adults, increasing the probability of infectious bearing fruits in swamps forests in the parasitic intensity (number of filariae per mosquitoes transmitting diseases (Ramasamy and Surrendran, 2012). infected host) in Lagothrix l. poeppigii in the Yavari-Mirin River basin (n = 88). Culicoides (Arthropoda: Ceratopogonidae) is the main vector for the 4 D.F. Conga et al. Acta Tropica 235 (2022) 106670 Fig. 2. Trends in river water level, rain days, percentage of trees bearing fruits in swamp forest; and (B) rainfall (dashed line) and parasitic intensity (number of filariae per infected host) in Lagothrix l. poeppigii in the Yavari-Mirin River basin (n = 88). microfilariae of the genus Dipetalonema in primates (Eberhard et al., 2003). However, this relationship could be also inverse, in which a 1979; Travi et al., 1985), but Simulids may also act as vectors (Tidwell higher density of hosts may lead to higher amplification of pathogen and Tidwell, 1982). Previous studies showed increasing abundance of transmission (Weaver and Reisen, 2010) and higher concentration and Culicoides and Simulids during the rainy season in the Amazon (Lacey, richness of helminths (Arneberg et al., 1998; Morand and Poulin, 1998). 1981; Velasques et al., 2012; Gusmão et al., 2019). However, aalthough Further studies including a large number of species should clarify mosquitoes require standing water to reproduce, excess rainfall can be whether and which of these patterns apply for NHPs in Amazonia. disruptive to their reproductive cycle by removing aquatic stages from Studies relating the body mass of hosts and parasitic infection are breeding sites (Benedum et al., 2018), decreasing the incidence of scarce in wild animals. Larger and heavier wild primates can have more mosquito-borne diseases (Seidahmed and Eltahir, 2016). Vector ecology quantities of adult specimen’s parasites compared to smaller and lightly is key to understanding risk factors associated with infection rate, but we hosts (Notarnicola, 2004). Furthermore, susceptibility to mosquito bites have no supporting information on vector abundance, biting rates and probably depends on mosquitoes’ preferences for choosing larger hosts actual infection of the vectors. This lack of information prevents us from because they are more attractive than smaller ones (Takken and Ver­ explaining the increased parasitic intensity observed during the month hulst, 2013), resulting in a positive correlation between host size and of April, which could be related to vector behavior. Further studies are parasitic infection (Daviews et al., 1991). However, we found no cor­ needed to elucidate the relationship between the ecology of vectors and relation among those variables in our study area, possibly because pri­ filarial infections. mates in natural habitats, opportunities for parasite colonization depend Beyond climatic factors and fruit shortage, human impacts on habi­ more closely on how hosts are available in a given area than on how tats have been shown to influence parasite infections in NHP. For large the hosts are (Morand and Poulin, 1998). instance, logging activities were shown to increase gastrointestinal In terms of reproductive state, studies on domestic animals show that parasite infections in African primates compared to undisturbed forests females in advanced stages of pregnancy stage are more susceptible to (Gillespie et al., 2005). Our results reinforce the importance of palm parasitic infection than males, due to immune depletion during the trees in swamp-forests for conservation, due to their direct contribution gestation period (Jamieson et al., 2006; Henriquez et al., 2010). How­ to the diet (Fang et al., 2008) and the health status of primate ever, in our study, reproductive state was not significantly correlated populations. with filarial infection, probably due to the small sample size of pregnant Despite great efforts to study the ecological and epidemiological females. mechanisms of diseases, the essential factors determining their trans­ mission cycles are still poorly understood (Weaver and Reisen, 2010). In 5. Conclusion our study, the prevalence, intensity and abundance of parasites in NHPs were not related to the biological variables studied; probably due to the The dynamics of parasite-host interactions in wild primates may be low sample size in terms of genera. From an ecological point of view, the key to understanding the mechanisms behind filariasis parasitism and infection by intestinal nematodes with direct life cycles may regulate the transmission in humans living close to tropical forest areas and, conse­ density and distribution of primate populations, by influencing the quently, support the development of effective sanitary measures and health and reproductive capacity of hosts (Scott, 1988; Nunn et al., control of filariasis in this context. In addition, the effects of global 5 D.F. Conga et al. Acta Tropica 235 (2022) 106670 climate change on infectious diseases, especially vector-borne diseases, wildlife management. We also thank the institutional support provided are uncertain and require ecological information. However, epidemio­ by the Peruvian Forestry and Wildlife Service (Ethical Committee for logical data on free-living species are usually scarce, because of the Wildlife Research, No0350–2012-AG-DGFFS-DGEFFS; No0249–2013- difficulty in obtaining biological and epidemiological samples. This AG-DGFFS-DGEFFS), Earthwatch Institute and Fundació Autònoma study developed a participatory collection with local subsistence Solidària (Universidad Autónoma de Barcelona). hunters that allowed us to achieve a sufficient sample size to show how climate influence filarial infection in free-living NHP in the rural References Amazon. These results may inform predictions on the prevalence and spread of disease in changing climates. We observed a significant dif­ Adami, Y.L., Herzog, M.M., 2008. Mansonelose no Médio Rio Purus (Amazonas). Revista Eletrônica de Comunicação, Informação e Inovação em Saúde. Rio de Janeiro 2 (1), ference in parasitic parameters among NHP genera, but the small 58–62. https://doi.org/10.3395/reciis.v2i1.839. number of genera studied and the low sample size for some of the genera Ayres, J.M., 1986. The White Uakaris and the Amazonian flooded Forests. University of did not allow observing the effect of biological factors, such as density, Cambridge, Cambridge. Ph.D. dissertation. Arneberg, P., Skorping, A., Grenfell, B., Read, A.F., 1998. Host densities as determinants group size and body mass, on parasitic parameters. Ecological studies of abundance in parasite communities. Proc. R. Soc. B 265, 1283–1289. https://doi. such as the one presented here may improve the understanding of org/10.1098/rspb.1998.0431. pathogen transmission of neglected diseases in humans that share the Bain, O., Diagne, M., Muller, R., 1987. Une cinquieme filaire du genre Dipetalonema, parasite de singes sudaméricains. Ann. Parasitol. Hum. Comp. 62, 262–270. https:// same ecosystem, and provide valuable information to study the possible doi.org/10.1051/parasite/1987623262. consequences of global warming on the rates of these infections. Bain, O., Petit, G., Rosales, L., 1986. Filaires de Singes sud-américains. Bull. Mus. Natl. Hist. Nat. A 8, 513–542. https://doi.org/10.1017/S0031182021000901. Beltrán, M., Cancrini, G., Reátegui, G., Melgar, R., Ayllón, C., Garaycochea, M., Reyes, R., Compliance with ethical standards Lammie, P.J., 2008. Filariosis humana en la selva peruana: reporte de tres casos. Rev. Peru Med. Exp. Salud Publica 25 (2), 257–260. All applicable institutional and/or national guidelines for the care Benedum, C.M., Seidahmed, O.M.E., Eltahir, E.A.B., Markuzon, N., 2018. Statistical and use of animals were followed. The research and sample collection modeling of the effect of rainfall flushing on dengue transmission in Singapore. PLoS Negl. Trop. Dis. 12 (12), e0006935 https://doi.org/10.1371/journal.pntd.0006935. protocol were approved by the Peruvian Forestry and Wildlife Service Bowler, M., Bodmer, R.E., 2011. Diet and food choice in Peruvian Red Uakaris (Cacajao (Ethical Committee for Wildlife Research, No0350–2012-AG-DGFFS- calvus ucayalii): selective or opportunistic seed predation? Int. J. Primatol. 32, DGEFFS; No0249–2013-AG-DGFFS-DGEFFS). 1109–1112. https://doi.org/10.1007/s10764-011-9527-6. Branco, B.C., Chamon, W., Belfort, R., Belfort, J.R., Costa, A.J.A., 1998. Achados oculares entre habitantes do Município de Pauiní e possível associação entre lesões corneanas Data availability statement e mansonelose na Amazônia. Arq. Bras. Oftalmol. 61 (6), 647–682. https://doi.org/ 10.5935/0004-2749.19980011. Buckland, S., Anderson, D., Burnham, K., Laake, J., Borchers, D., Thomas, L., 2001. The data that support the findings of this study are available in the Introduction to Distance sampling: Estimating Abundance of Biological Populations. Pangaea repository at 10.1594/PANGAEA.913249 (Conga et al., 2020). Oxford University Press, Oxford. Burnham, K.P., Anderson, D.R., 2004. Multimodel inference: understanding AIC and BIC in model selection. Sociol. Methods Res. 33, 261–304. https://doi.org/10.1177/ Funding information 0049124104268644. Bush, A.O., Lafferty, K.D., Lotz, J.M., Shestak, A.W., 1997. Parasitology meets ecology on This work was also supported by ERANet17/HLH-0271, and by the its own terms: Margolis et al. revisited. J. Parasitol. 83, 575–583. https://doi.org/ 10.2307/3284227. National Council for Scientific and Technological Development (CNPq) Conga, D.F., El Bizri, H.R., Gomez-Puerta, L.A., Mayor, P., 2020. Parasitic parameters of (grant number 201,475/2017–0). D.F. Conga is a part of PNPD-CAPES natural filarial infection in non-human primates from Loreto region, northeast of the (UFRA) scholarship and this work was part of his Doctoral Thesis Peruvian Amazon. PANGAEA. https://doi.org/10.1594/PANGAEA.913249. Conga, D.F., Mayor, P., Furtado, A.P., Giese, E.G., Santos, J.N., 2018a. Occurrence of within the Program in Biology of Infectious and Parasitic Agents of the Dipetalonema gracile in a wild population of woolly monkey Lagothrix poeppiigii in the Universidade Federal do Pará. northeastern Peruvian Amazon. Rev. Bras. Parasitol. Vet. 27 (2), 154–160. https:// doi.org/10.1590/S1984-296120180014. CRediT authorship contribution statement Conga, D.F., Mayor, P., Furtado, A.P., Giese, E.G., Santos, J.N., 2018b. Co-infection with filarial nematodes in Sapajus macrocephalus and Cebus albifrons (Primates: cebidae) from the Peruvian Amazon. J. Helminthol. 93 (3), 375–378. https://doi.org/ David F. Conga: Conceptualization, Writing – original draft. Hani 10.1017/S0022149X18000287. R. El Bizri: Formal analysis. Carlos González Crespo: Formal analysis, Daviews, C.R., Ayres, J.M., Dye, C., Deane, L.M., 1991. Malaria infection rate of amazonian primates increases with body weight and group size. Funct. Ecol. 5, Writing – review & editing. Luis A. Gomez-Puerta: Writing – review & 655–662. https://doi.org/10.2307/2389485. editing. Gabriela M. Ulloa-Urizar: . Pedro E. Pérez-Peña: Data cura­ Dew, J.L., 2005. Foraging, food choice, and food processing by sympatric ripe-fruit tion, Writing – review & editing. Mark Bowler: Writing – review & specialists: lagothrix lagotricha poeppigii and Ateles belzebuth belzebuth. Int. J. Primatol. 26 (5), 1107–1135. https://doi.org/10.1007/s10764-005-6461-5. editing. Pedro Mayor: Conceptualization, Visualization, Methodology, Eberhard, M.L., Lowrie Jr., R.C., Orihel, T.C., 1979. Development of Dipetalonema gracile Data curation, Writing – original draft. and D. caudispina to the infective stage in Culicoides hollensis. J. Parasitol. 65, 89–95. Eberhard, M.L., Orihel, T.C., 1984. The genus Mansonella (syn. Tetrapetalonema): a new classification. Ann. Parasitol. Hum. Comp. 59, 483–496. https://doi.org/10.1051/ Declaration of Competing Interest parasite/1984595483. Emmons, L.H., Feer, F., 1990. Neotropical Rainforest Mammals: a Field Guide. University The authors declare that they have no known competing financial of Chicago Press, Chicago. Endo, W., Peres, C.A., Haugaasen, T., 2016. Flood pulse dynamics affects exploitation of interests or personal relationships that could have appeared to influence both aquatic and terrestrial prey by Amazonian floodplain settlements. Biol. the work reported in this paper. Conserv. 201, 129–136. https://doi.org/10.1016/j.biocon.2016.07.006. Famakinde, D.O., 2018. Mosquitoes and the lymphatic filarial parasites: research trends Data Availability and budding roadmaps to future disease eradication. Trop. Med. Infect. Dis. 3 (1), 4. https://doi.org/10.3390/tropicalmed3010004. Fang, T., Bodmer, R., Puertas, P., Mayor, P., Perez, P., Acero, R., Hayman, D., 2008. Data will be made available on request. Certificación de Pieles de Pecaries (Tayassu Tajacu y T. pecari) En La Amazonía peruana: Una estrategia Para La Conservación y Manejo de Fauna Silvestre en La Amazonia peruana. Wust Editions-Darwin Institute, Lima. Ford, S.M., 1994. Evolution of sexual dimorphism in body weight in platyrrhines. Am. J. Acknowledgements Primatol. 34, 221–244. https://doi.org/10.1002/ajp.1350340211. Gaillard, C.M., Pion, S.D., Hamou, H., Sirima, C., Bizet, C., Lemarcis, T., Rodrigues, J., Esteban, A., Peeters, M., Mpoudi Ngole, E., Mombo, I., Liégeois, F., Martin, C., The authors gratefully acknowledge the people of all rural commu­ Boussinesq, M., Locatelli, S., 2020. Detection of DNA of filariae closely related to nities who participated actively in sample collection, demonstrating that Mansonella perstans in faecal samples from wild non-human primates from Cameroon communal participation is an important step in the development of 6 D.F. Conga et al. Acta Tropica 235 (2022) 106670 and Gabon. Parasit. Vectors 13 (1), 313. https://doi.org/10.1186/s13071-020- Muehlenbein, M.P., 2006. Intestinal parasite infections and fecal steroid levels in wild 04184-1. chimpanzees. Am. J. Phys. Anthropol. 130, 546–550. https://doi.org/10.1002/ Gillespie, T.R., Chapman, C.A., Greiner, E.C., 2005. Effects of logging on gastrointestinal ajpa.20391. parasite infections and infection risk in African primates. J. Appl. Ecol. 42, 699–707. Notarnicola, J., 2004. Taxonomía y Biología De Las Filarias De Animales Silvestres y de https://doi.org/10.1111/j.1365-2664.2005.01049.x. Importancia Sanitaria En La República Argentina. Universidad Nacional de La Plata, Gusmão, G.M.C., Brito, G.A., Moraes, L.S., Bandeira, M.D.C.A., Rebêlo, J.M.M., 2019. Buenos Aires. Ph.D. dissertation. Temporal variation in species abundance and richness of Culicoides (Diptera: Nunn, C.L., Altizer, S., Jones, K.E., Sechrest, W., 2003. Comparative Tests of parasite ceratopogonidae) in a tropical equatorial area. J. Med. Entomol. 27 (4), 1013–1018. species richness in Primates. Am. Nat. 162, 597–614. https://doi.org/10.1086/ https://doi.org/10.1093/jme/tjz015, 56. 378721. Haugaasen, T., Peres, C.A., 2005. Primate assemblage structure in Amazonian flooded Peres, C.A., 1999. General guidelines for standardizing line-transect surveys of tropical and unflooded forests. Am. J. Primatol. 67, 243–258. https://doi.org/10.1002/ forest primates. Neotrop. Primates 7, 11–16. ajp.20180. Pitman, N., Vriesendorp, C., Moskovits, D., 2003. Perú: Yavarí. Rapid Biological Henriquez, F.L., Menzies, F.M., Roberts, C.W., 2010. Pregnancy and susceptibility to Inventories Report 11. The Field Museum, Chicago, IL. parasites. In: Klein, S.L., Roberts, C.W. (Eds.), Sex Hormones and Immunity to Core Team, R., 2021. R: A language and Environment For Statistical Computing. R Infection. Springer, Berlin, pp. 227–256. Foundation for Statistical Computing, Vienna, Austria. URL. https://www.R-project. Herrera, J., Arróspide, N., González, S., Celis, J., Solano, D., Hermenegildo, L., org/. Cabezas, C., 2013. Report of four clinical cases of filariasis in Alto Nanay, Loreto. Ramasamy, R., Surendran, S.N., 2012. Global climate change and its potential impact on Rev. Peru Med. Exp. Salud Publica 30 (3), 506–511. disease transmission by salinity-tolerant mosquito vectors in coastal zones. Front. Hershkovitz, P., 1990. Titis, new world monkeys of the genus Callicebus (Cebidae, Physiol. 3, 198. https://doi.org/10.3389/fphys.2012.00198. Platyrrhini): a preliminary taxonomic review. Fieldiana Zool. 55, 1–109. https://doi. Rudolphi, C.A., 1809. Entozoorum sive vermium intestinalium. Hist. Nat. 2, 457. org/10.5962/bhl.title.2843. Scott, M.E., 1988. The impact of infection and disease on animal populations: Jack, K., 2007. The Cebines: toward an explanation of variable social structure. In: implications for conservation biology. Conserv. Biol. 2, 40–56. https://doi.org/ Campbell, C.J., Fuentes, A., Mackinnon, K.C., Panger, M., Bearder, S.K. (Eds.), 10.1111/j.1523-1739.1988.tb00334.x. Primates in Perspective. Oxford University Press, Oxford, pp. 107–123. Seidahmed, O.M., Eltahir, E.A., 2016. A sequence of flushing and drying of breeding Jamieson, D.J., Theiler, R.N., Rasmussen, S.A., 2006. Emerging infections and habitats of aedes aegypti (L.) Prior to the low dengue season in Singapore. PLoS pregnancy. Emerg. Infect. Dis. 12, 1638–1643. https://doi.org/10.3201/ Negl. Trop. Dis. 10, e0004842 https://doi.org/10.1371/journal.pntd.0004842. eid1211.060152. Smith, R.J., Jungers, W.L., 1997. Body mass in comparative primatology. J. Hum. Evol. Klein, S.L., 2004. Hormonal and immunological mechanisms mediating sex differences in 32, 523–559. https://doi.org/10.1006/jhev.1996.0122. parasite infection. Parasite Immunol. 26, 247–264. https://doi.org/10.1111/j.0141- Stevenson, P.R., Quiñones, M.J., Ahumada, J.A., 2000. Influence of fruit availability on 9838.2004.00710.x. ecological overlap among four Neotropical primates at Tinigua National Park, Kuhn, K., Campbell-Lendrum, D., Haines, A., Cox, J., 2005. Using Climate to Predict Colombia. Biotropica 32, 533–544. https://doi.org/10.1111/j.1744-7429.2000. Infectious Disease Epidemics. World Health Organization, Geneva. tb00499.x. Lacey, L.A., 1981. Simulídeos antropofílicos no parque nacional da Amazônia (Tapajós), Storti, E.F., 1993. Biologia floral de Mauritia flexuosa Lin. Fil. na região de Manaus, AM, Brasil, com referências aos efeitos no Homem. Bolletin Sanit. Panama 90 (4), Brasil. Acta Amazon. 23 (4), 371–381. https://doi.org/10.1590/1809- 326–338. 43921993234381. Lu, F.E., 1999. Changes in Subsistence Patterns and Resource Use of the Huaroni Indians Sutherland, W.J., 2000. The Conservation handbook: Techniques in research, in the Ecuadorian Amazon. University of North Carolina, Chapel Hill, NC. Management and Policy. Blackwell Science, Oxford. Marquardt, D.W., 1970. Generalized inverses, ridge regression, biased linear estimation, Takken, W., Verhulst, N.O., 2013. Host preferences of blood-feeding mosquitoes. Annu. and nonlinear estimation. Technometrics 12, 591–612. https://doi.org/10.1080/ Rev. Entomol. 58, 433–453. https://doi.org/10.1146/annurev-ento-120811- 00401706.1970.10488699. 153618. Martínez-Mota, R., Garber, P.A., Palme, R., Gillespie, T.R., 2017. The relative effects of Therneau, T., Atkinson, B., Ripley, B., 2013. Rpart: recursive Partitioning. R Package reproductive condition, stress, and seasonality on patterns of parasitism in wild Version 4.1-15. http://CRAN.R-project.org/package=rpart. female black howler monkeys (Alouatta pigra). Am. J. Primatol. 79, e22669. https:// Tidwell, M.A., TidwelL, M.A., 1982. Development of Mansonella ozzardi in Simulium doi.org/10.1002/ajp.22669. amazonicum, S. argentiscutum, and Culicoides insinuatus from Amazonas, Colombia. Medeiros, J.F., Py-Daniel, V., 2004. Seasonality, parity rates and transmission indices of Am. J. Trop. Med. Hyg. 31 (6), 1137–1141. Mansonella ozzardi (Manson) (Nematoda: onchocercidae) by Cerqueirellum Travi, B.L., Eberhard, M.L., Lowrie Jr., R.C., 1985. Development of Dipetalonema gracile argentiscutum (Shelley & Luna Dias) (Diptera: simuliidae) in a lower Solimões River in the squirrel monkey (Saimiri sciureus), with notes on its biology. J. Parasitol. 71 community, Amazonas, Brazil. Acta Amazon. 34 (2), 201–207. https://doi.org/ (1), 17–19. 10.1590/S0044-59672004000200008. Vanderhoeven, E., Notarnicola, J., Agostini, I., 2017. First record of Dipetalonema robini Medeiros, J.F., Py-Daniel, V., Barbosa, U.C., Ogawa, G.M., 2009. Current profile of Petit, Bain and Roussilhon 1985 (Nematoda: onchocercidae) parasitizing Sapajus Mansonella ozzardi (Nematoda: onchocercidae) in communities along the Ituxi river, nigritus in northeastern Argentina. Mastozool. Neotrop. 24 (2), 7483–7488. Lábrea municipality, Amazonas, Brazil. Mem. Inst. Oswaldo Cruz 103 (4), 409–411. Velasques, S.N., Medeiros, J.F., Pessoa, F.A.C., Julião, G.R., Souza, C.C.S., Camargo, L.M. https://doi.org/10.1590/S0074-02762008000400017. A., 2012. Ocorrência e antropofilia de simulídeos em comunidades ribeirinhas de Molin, R., 1858. Versuch einer monographie der filarien. Sitzungsb. Denkschriften der rondônia. EntomoBrasilis 5 (1), 59–64. kaiserlichen der wissenschaften. Wien. Math. Naturwiss 28, 365–461. Weaver, S.C., Reisen, W.K., 2010. Present and future arboviral threats. Antivir. Res. 85, Morand, S., Poulin, R., 1998. Density, body mass and parasite species richness of 328–345. https://doi.org/10.1016/j.antiviral.2009.10.008. terrestrial mammals. Evol. Ecol. 12, 717–727. https://doi.org/10.1023/A: Webster-Marketon, J.I., Glaser, R., 2008. Stress hormones and immune function. Cell. 1006537600093. Immunol. 252, 16–26. https://doi.org/10.1016/j.cellimm.2007.09.006. 7