Influence of trypanocidal therapy on the haematology of vervet monkeys experimentally infected with Trypanosoma brucei rhodesiense.

The aim of this study was to characterise the sequential haematological changes in vervet monkeys infected with Trypanosoma brucei rhodesiense and subsequently treated with sub-curative diminazene aceturate (DA) and curative melarsoprol (MelB) trypanocidal drugs. Fourteen vervet monkeys, on a serial timed-kill pathogenesis study, were infected intravenously with 10(4) trypanosomes of a stabilate T. b. rhodesiense KETRI 2537. They were treated with DA at 28 days post infection (dpi) and with MelB following relapse of infection at 140 dpi. Blood samples were obtained from the monkeys weekly, and haematology conducted using a haematological analyser. All the monkeys developed a disease associated with macrocytic hypochromic anaemia characterised by a reduction in erythrocytes (RBC), haemoglobin (HB), haematocrit (HCT), mean cell volume (MCV), platelet count (PLT), and an increase in the red cell distribution width (RDW) and mean platelet volume (MPV). The clinical disease was characteristic of human African trypanosomiasis (HAT) with a pre-patent period of 3 days. Treatment with DA cleared trypanosomes from both the blood and cerebrospinal fluid (CSF). The parasites relapsed first in the CSF and later in the blood. This treatment normalised the RBC, HCT, HB, PLT, MCV, and MPV achieving the pre-infection values within two weeks while RDW took up to 6 weeks to attain pre-infection levels after treatment. Most of the parameters were later characterised by fluctuations, and declined at one to two weeks before relapse of trypanosomes in the haemolymphatic circulation. Following MelB treatment at 140 dpi, most values recovered within two weeks and stabilised at pre-infection levels, during the 223 days post treatment monitoring period. It is concluded that DA and MelB treatments cause similar normalising changes in the haematological profiles of monkeys infected with T. b. rhodesiense, indicating the efficacy of the drugs. The infection related changes in haematology parameters, further characterise the vervet monkey as an optimal induced animal model of HAT. Serial monitoring of these parameters can be used as an adjunct in the diagnosis and prognosis of the disease outcome in the vervet monkey model.

Biochemical changes in cerebrospinal fluid of Chlorocebus aethiops naturally infected with zoonotic Meningonema peruzzii.

BACKGROUND: Thirty-four wild Chlorocebus aethiops monkeys were trapped for research purposes. METHODS: During routine quarantine check-up, cerebrospinal fluid (CSF) and blood were microscopically examined for parasites. Estimations of CSF protein levels were made by the biuret method and the white cell counts by the hemocytometer. RESULTS: Seven monkeys demonstrated microfilariae in blood and CSF. This was accompanied by a two- and ninefold increase in CSF total protein and white cell counts, respectively. Necropsy of one of the blood and CSF microfilariae-positive animals revealed the presence of adult worms in the brain meninges. The parasites were identified as the zoonotic filaroid nematode Meningonema peruzii. CONCLUSIONS: Wild C. aethiops monkeys developed CSF changes resulting, most probably, from infection with M. peruzii. Moreover, the monkeys could be acting as an important reservoir. The study highlights the need for epidemiological and pathogenological studies of this parasite, which is of public health significance. Moreover, C. aethiops proved to be a useful primate model for the study of this zoonotic infection.

Secondary sexual coloration and CSF 5-HIAA are correlated in vervet monkeys (Cercopithecus aethiops sabaeus).

BACKGROUND: Identifying indirect markers of the physiology or neuroendocrinology of a primate can provide a powerful tool to scientists. Anecdotal descriptions and recent experimental evidence suggests that the colorful sexual skin in adult male vervet monkeys (Cercopithecus aethiops sabaeus) might be sensitive to social changes, including dominance relationships, which could be related to serotonergic activity. The present study examined whether individual differences in scrotal coloration were related to cisternal cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid (CSF 5-HIAA) in a captive population of vervet monkeys. RESULTS: Darkly colored males had relatively higher CSF 5-HIAA concentrations than paler males, and scrotal color hue was also related CSF 5-HIAA concentrations. CONCLUSIONS: These preliminary data are compatible with the hypothesis that scrotal coloration serves as an indirect marker of serotonergic activity. These findings suggest that color assessments might be useful to consider for study design, as well as for animal welfare and captive management.

Alzheimer's disease abeta vaccine reduces central nervous system abeta levels in a non-human primate, the Caribbean vervet.

Amyloid beta (Abeta) protein immunotherapy lowers cerebral Abeta and improves cognition in mouse models of Alzheimer's disease (AD). Here we show that Caribbean vervet monkeys (Chlorocebus aethiops, SK) develop cerebral Abeta plaques with aging and that these deposits are associated with gliosis and neuritic dystrophy. Five aged vervets were immunized with Abeta peptide over 10 months. Plasma and cerebral spinal fluid (CSF) samples were collected periodically from the immunized vervets and five aged controls; one monkey per group expired during the study. By Day 42, immunized animals generated plasma Abeta antibodies that labeled Abeta plaques in human, AD transgenic mouse and vervet brains; bound Abeta1-7; and recognized monomeric and oligomeric Abeta but not full-length amyloid precursor protein nor its C-terminal fragments. Low anti-Abeta titers were detected in CSF. Abetax-40 levels were elevated approximately 2- to 5-fold in plasma and decreased up to 64% in CSF in immunized vervets. Insoluble Abetax-42 was decreased by 66% in brain homogenates of the four immunized animals compared to archival tissues from 13 age-matched control vervets. Abeta42-immunoreactive plaques were detected in frontal cortex in 11 of the 13 control animals, but not in six brain regions examined in each of the four immunized vervets. No T cell response or inflammation was observed. Our study is the first to demonstrate age-related Abeta deposition in the vervet monkey as well as the lowering of cerebral Abeta by Abeta vaccination in a non-human primate. The findings further support Abeta immunotherapy as a potential prevention and treatment of AD.

CSF monoamines, age and impulsivity in wild grivet monkeys (Cercopithecus aethiops aethiops).

Brain monoaminergic activity has been associated with behaviors, such as impulsive risk-taking, that tend to peak during adolescence in humans and nonhuman primates. This study was designed to assess natural variation in monoamine neurotransmitter metabolism in relation to age and behavioral impulsivity in grivet monkeys (Cercopithecus aethiops aethiops) living in their native habitat and subject to natural ecological pressures. Cisternal cerebrospinal fluid, collected from 22 animals living in the Awash National Park, Ethiopia, was assayed for the major metabolites of serotonin (5-hydroxyindoleacetic acid, 5-HIAA), dopamine (homovanillic acid, HVA) and norepinephrine (3-methoxy-4-hydroxyphenylglycol, MHPG). Concentrations of HVA declined significantly from one year of age to older adulthood. Further, a significant curvilinear relationship was identified between age and the 5-HIAA/HVA ratio, with the trough coinciding with the period of adolescence. Finally, behavioral impulsivity, as measured by re-entering baited traps a second time after the animal had already been captured and sampled for CSF, was related to lower levels of MHPG. The results suggest that normal variation in central monoaminergic activity may have functional consequences in wild populations.