Flotation techniques (FLOTAC and mini-FLOTAC) for detecting gastrointestinal parasites in howler monkeys
Alvarado-Villalobos et al. Parasites & Vectors
Flotation techniques (FLOTAC and mini-FLOTAC) for detecting gastrointestinal parasites in howler monkeys
Mayra Alejandra Alvarado-Villalobos 0 3
Giuseppe Cringoli 2
Maria Paola Maurelli 2
Aurelie Cambou 1
Laura Rinaldi 2
Arturo Barbachano-Guerrero
Roger Guevara
Colin A. Chapman
Juan Carlos Serio-Silva 0 3
0 Red de Biología y Conservación de Vertebrados, Instituto de Ecología A.C , Xalapa, 91070 Veracruz , Mexico
1 ENSAIA (Ecole National e Supérieure d'Ágronomie et des Industries Alimentaires) , Vandoeuvre-lés-Nancy , France
2 Unit of Parasitology and Parasitic Diseases, Department of Veterinary Medicine and Animal Productions, University of Naples Federico II , Naples , Italy
3 Red de Biología y Conservación de Vertebrados, Instituto de Ecología A.C , Xalapa, 91070 Veracruz , Mexico
Background: Analyses of environmental correlates of the composition of gastrointestinal parasite communities in black howler monkeys (Alouatta pigra) have been hindered by inadequate calibration techniques of detection and quantification methods of the parasites. Here we calibrate samples and compare the likelihood of parasite detection using two flotation techniques, FLOTAC and Mini-FLOTAC, and compare flotation solution, preservation method and dilution ratio for egg detection and counts of the most common parasites (Controrchis spp. and Trypanoxyuris spp.) in howler monkeys. Results: For samples preserved in 5% formalin, the Mini-FLOTAC technique was the best option for qualitative and quantitative copro-microscopic analysis. This technique displays an 83.3% and 100% detection of Controrchis spp. and Trypanoxyuris spp. infections, respectively. For the trematode Controrchis spp., more eggs per gram of feces (EPG) were recorded with the flotation solution (FS) #7 (zinc sulfate; specific gravity SG = 1.35) at 1:20 and 1:25 dilution than other methods. By contrast, for the nematode Trypanoxyuris spp., the best results were recorded with FS1 (sucrose and formaldehyde; SG = 1.20) at 1:10 dilution. Conclusions: We recommend the Mini-FLOTAC technique for general use with parasite analysis on frugivore/ folivores like the howler monkey, especially if many samples are analyzed. The technique has a high detection rate and the best EPG counts, allowing the qualitative and quantitative analysis of parasite load among the species or populations without the need for specialized equipment.
Quantitative flotation; Gastrointestinal parasites; Nematodes; Trematodes; Howler monkeys; Alouatta
Background
The accurate detection of the prevalence and intensity
of gastrointestinal parasite infections is key to
understanding the effect of parasites on the biology, behavior,
and the conservation of hosts. Gastrointestinal parasites
are most often surveyed in the feces [
1
] of wild host
populations using light microscopy [
2–4
], which is
particularly effective where the feces of host populations
can be identified and collected in the wild, as this
eliminates the need to capture or handle host individuals.
An increasing number of studies have focused on the
gastrointestinal parasites of howler monkeys (Alouatta
spp.), in which polyparasitism is common, including
helminths, protozoans and acanthocephalans [
5
]. Among
these parasites, trematodes (Controrchis spp.) and
nematodes (Trypanoxyuris spp.) are the most common
gastrointestinal parasites of howler monkeys [
5, 6
].
Controrchis spp. are common in most studies [
5, 7
] and
may influence the ecology of the host [
8
]. By contrast,
Trypanoxyuris spp. appear to be indicators of ecosystem
health with low prevalence in human dominated
landscapes and high prevalence in more natural landscapes
[
9
]. Most studies report low levels of Controrchis spp.
and Trypanoxyuris spp. parasitism in the black howler
monkey (Alouatta pigra) [
7, 8
], possibly due to
unsuitable sampling or analytical methods.
Consequently, standardization of the copro-microscopic
techniques is essential for the diagnosis of gastrointestinal
parasites.
In wild primates, including howler monkeys, parasitic
infections are typically detected by identifying eggs,
larvae, oocysts, or cysts in the feces of the host by
flotation procedures [
10–15
] or sedimentation
techniques [
8, 10, 12
]. Sodium nitrate (NaNO3) is a common
flotation solution (FS) for fecal samples from wild
primates [
16, 17
]. However, studies of black howler
monkeys (Alouatta pigra) have also used sodium chloride
(NaCl) [
11, 18
], zinc sulfate (ZnSO4) [
13–15
], and
sucrose (C12H22O11) for samples preserved in 10% formalin
[
8, 12, 14, 15
]. In folivore-frugivore primates, such as
Alouatta pigra [
19–21
], identification of parasites in fecal
samples is often complicated by the high fiber content of
their diet [
19
], as well as the common presence of pollen,
plant tissue, flowers, and invertebrate fragments
(accidentally ingested with the plants) [
19, 21, 22
], all of which (...truncated)