Haematology of Experimental Trypanosoma Brucei Rhodesiense Infection in Vervet Monkeys

Haematological aberrations associated with human infective trypanosomes were investigated in the vervet monkey model of the Rhodesian sleeping sickness. Four monkeys were infected intravenously with 104 Trypanosoma brucei rhodesiense and monitored for changes in the blood profile using a haematological analyser. A chronic infection lasting between 48 and 112 days was observed. Microcytic hypochromic anaemia, which was characterized by a decline in packed cell volume (PCV), red blood cell (RBC) numbers, mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCH) developed at an early stage, and persisted throughout the infection. The mean platelet counts declined significantly from 3 x 105/\u3bcl (day 0 post infection) to 6.8 x 104/\u3bcl (day 7 post infection) and remained low in all the animals. However, the mean platelets volume rose during the course of the infection. An initial decline in total white blood cell (WBC) counts occurred between day 0 and 7 (3.1 x 106/\u3bcl) and remained low up to day 35 post infection (3.5 x 106/\u3bcl). This was followed by an increase in WBC counts, principally associated with increased lymphocyte numbers. It is concluded that microcytic hypochromic anaemia, thrombocytopaenia and an initial leucocytopaenia are the most important haematological changes associated with a chronic infection of T.b. rhodesiense infection in vervet monkeys

<i>Trypanosoma brucei rhodesiense</i> transmitted by a single tsetse fly bite in vervet monkeys as a model of human African trypanosomiasis

Sleeping sickness is caused by a species of trypanosome blood parasite that is transmitted by tsetse flies. To understand better how infection with this parasite leads to disease, we provide here the most detailed description yet of the course of infection and disease onset in vervet monkeys. One infected tsetse fly was allowed to feed on each host individual, and in all cases infections were successful. The characteristics of infection and disease were similar in all hosts, but the rate of progression varied considerably. Parasites were first detected in the blood 4-10 days after infection, showing that migration of parasites from the site of fly bite was very rapid. Anaemia was a key feature of disease, with a reduction in the numbers and average size of red blood cells and associated decline in numbers of platelets and white blood cells. One to six weeks after infection, parasites were observed in the cerebrospinal fluid (CSF), indicating that they had moved from the blood into the brain; this was associated with a white cell infiltration. This study shows that fly-transmitted infection in vervets accurately mimics human disease and provides a robust model to understand better how sleeping sickness develops

Anti-Severe Acute Respiratory Syndrome Coronavirus 2 Immunoglobulin G Antibody Seroprevalence Among Truck Drivers and Assistants in Kenya.

In October 2020, anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G seroprevalence among truck drivers and their assistants (TDA) in Kenya was 42.3%, higher than among healthcare workers and blood donors. Truck drivers and their assistants transport essential supplies during the coronavirus disease 2019 pandemic, placing them at increased risk of being infected and of transmitting SARS-CoV-2 over a wide geographical area

Seroprevalence of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 Among Healthcare Workers in Kenya.

BACKGROUND: Few studies have assessed the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCWs) in Africa. We report findings from a survey among HCWs in 3 counties in Kenya. METHODS: We recruited 684 HCWs from Kilifi (rural), Busia (rural), and Nairobi (urban) counties. The serosurvey was conducted between 30 July and 4 December 2020. We tested for immunoglobulin G antibodies to SARS-CoV-2 spike protein, using enzyme-linked immunosorbent assay. Assay sensitivity and specificity were 92.7 (95% CI, 87.9-96.1) and 99.0% (95% CI, 98.1-99.5), respectively. We adjusted prevalence estimates, using bayesian modeling to account for assay performance. RESULTS: The crude overall seroprevalence was 19.7% (135 of 684). After adjustment for assay performance, seroprevalence was 20.8% (95% credible interval, 17.5%-24.4%). Seroprevalence varied significantly (P < .001) by site: 43.8% (95% credible interval, 35.8%-52.2%) in Nairobi, 12.6% (8.8%-17.1%) in Busia and 11.5% (7.2%-17.6%) in Kilifi. In a multivariable model controlling for age, sex, and site, professional cadre was not associated with differences in seroprevalence. CONCLUSION: These initial data demonstrate a high seroprevalence of antibodies to SARS-CoV-2 among HCWs in Kenya. There was significant variation in seroprevalence by region, but not by cadre

Population genetics of Anopheles funestus, the African malaria vector, Kenya

Abstract Background Anopheles funestus is among the major malaria vectors in Kenya and sub-Saharan Africa and has been recently implicated in persistent malaria transmission. However, its ecology and genetic diversity remain poorly understood in Kenya. Methods Using 16 microsatellite loci, we examined the genetic structure of An. funestus sampled from 11 locations (n = 426 individuals) across a wide geographical range in Kenya spanning coastal, western and Rift Valley areas. Results Kenyan An. funestus resolved as three genetically distinct clusters. The largest cluster (FUN1) broadly included samples from western and Rift Valley areas of Kenya with two clusters identified from coastal Kenya (FUN2 and FUN3), not previously reported. Geographical distance had no effect on population differentiation of An. funestus. We found a significant variation in the mean Plasmodium infectivity between the clusters (χ 2 = 12.1, df = 2, P = 0.002) and proportional to the malaria prevalence in the different risk zones of Kenya. Notably, there was variation in estimated effective population sizes between the clusters, suggesting possible differential impact of anti-vector interventions in represented areas. Conclusions Heterogeneity among Kenyan populations of An. funestus will impact malaria vector control with practical implications for the development of gene-drive technologies. The difference in Plasmodium infectivity and effective population size between the clusters could suggest potential variation in phenotypic characteristics relating to competence or insecticide resistance. This is worth examining in future studies

Progressive changes in haematology indices of vervet monkeys infected with <i>T.b. rhodesiense</i> cloned strains through cyclic (tsetse; <i>Glossina pallidipes</i>) transmission.

<p>Key: dpi = days post infection; T.b.r. = <i>Trypanosoma brucei rhodesiense</i>; a = Laboratory number of monkey; F = Female; M = Male; O = observed; NO = Not observed; fl = femtolitres; pg = picograms; g/dl = grams per decilitre; − = decreased; + = increased; NDA = No data available.</p

Changes in the mean corpuscular volume (MCV) mean corpuscular haemoglobin (MCH) and Red cell distribution width (RDW) in two vervet monkeys (•-554 and ▵-555) that were infected with <i>T.b. rhodesiense</i> KETRI 3928.

<p>Panel A: MCV; Panel B: MCH; and Panel C: RDW. Note that while both MCV and MCH decreased below pre-infection levels and remained low throughout; RDW increased throughout the infection.</p