Hard ticks (Acari: Ixodidae) and tick-borne diseases of sheep and goats in Africa: A review.

Ticks are leading vectors of economically important pathogens that affect small ruminants due to favourable climatic conditions across different regions of the African continent. They are responsible for both direct and indirect economic losses in the livestock industry. This review focuses on the species diversity of hard ticks, their biology, tick-borne diseases of sheep and goats including non-infectious disease, and risk factors to tick infestation in Africa. Furthermore, our review provides recent updates on distribution of ticks and tick-borne pathogens of small ruminants in Africa. It was observed that several species and subspecies of hard ticks belonging to the genera Hyalomma (Hy), Rhipicephalus (Rh), Ixodes (I) and Amblyomma (Am) were found infesting small ruminants across the different regions of the continent. Of these genera, Rhipicephalus ticks accounts for the majority of the registered species, with exactly 27 different species infesting small ruminant stocks comprising of different developmental instars and adults of the tick. Rhipicephalus decolaratus, Rh. e. evertsi and Rh. appendiculatus were the three most common Rhipicephalus species reported. Both protozoal (Babesia and Theileria) and bacterial (Anaplasma, Rickettsia, Ehrlichia, Coxiella and Mycoplasma) pathogens have being reported to be amplified in several hard tick species and/or small ruminant hosts. Furthermore, tick paralysis and lameness were non-infectious conditions attributed to tick infestations. Amblyomma hebraeum and Rh. glabroscutatum may cause lameness in goats, while Hy. rufipes is responsible for the same condition in Merino sheep. Host paralysis due to a neurotoxin released by female Rh. e. evertsi and I. rubicundus has been documented within the continent. We therefore advocate for the need of integrated control measures against tick-borne pathogens (TBPs) including their arthropod vectors, to be performed simultaneously to ease the burden of vector-borne diseases in small ruminant production.

Trypanocide usage in the cattle belt of southwestern Uganda.

Background: Systematic infrastructure and regulatory weaknesses over many decades, in communities struggling with animal African trypanosomiasis (AAT) would be expected to create an environment that would promote drug misuse and risk development of drug resistance. Here, we explore rural community practices of livestock keepers, livestock extension officers and drug shop attendants to determine whether appropriate practice was being followed in administration of trypanocides and other drugs. Methods: A questionnaire-based survey was undertaken in southwestern Uganda in 2022 involving 451 farmers who kept cattle, sheep or goats and 79 "professionals" who were either livestock extension officers or drug shop attendants. Results: Respondents reported using one or more type of trypanocidal drug on 80.1% of the 451 farms in the last 30 days. Diminazene aceturate was used on around three-quarters of farms, while isometamidium chloride was used on around one-fifth. Homidium bromide was used on less than 1% of farms. Cattle were significantly more likely to be treated with trypanocides than sheep or goats. On around two-thirds of farms, trypanocides were prepared and injected by farmers, with extension officers administering these drugs on most of the other third, especially on cattle farms. Almost all drugs were obtained from privately-owned drug shops. For treatment of AAT with trypanocides, prescription-only medicines were routinely used by farmers without professional supervision and in the absence of a definitive diagnosis. While a far greater proportion of professionals had a better education and had received training on the use of trypanocides than farmers, there was relatively little difference in their ability to use these drugs correctly. Farmers were more likely than professionals to use only DA to treat trypanosomiasis and were more likely to use antibiotics as well as trypanocidal drugs to treat the animal. Furthermore, they estimated, on average, that twice the recommended dose of either diminazene aceturate or isometamidium chloride was needed to treat a hypothetical 400 kg bovine. A minority of both farmers and professionals reported that they observed the recommended withdrawal times following injection of trypanocidal drugs and very few of either group knew the recommended withdrawal times for milk or meat. Only one in six farmers reported using the sanative pair (alternating use of diminazene aceturate and isometamidium chloride), to reduce the risk of drug resistant trypanosome strains emerging, while this approach was more widely used by professionals. Farmers reported using antibiotics more commonly than the professionals, especially in sheep and goats, raising concerns as to overuse and misuse of this critical class of drugs. In addition to using trypanocides, most farmers also reported using a topical veterinary pesticide for the control of ticks and tsetse. On average, farmers spent 12.2% of their income from livestock sales on trypanocides. Conclusion: This study highlights the complexity of issues involved in the fight against AAT using drug treatment. A multistakeholder campaign to increase awareness among farmers, drug shop attendants, and extension workers of the importance of adherence to recommended drug dosing, using the sanative pair and following recommended drug withdrawal guidance would promote best practice, reduce the risk of emergence of resistant strains of trypanosomes, and support enhanced food safety.

Systematic Review and Meta-Analysis on Human African Trypanocide Resistance.

Background Human African trypanocide resistance (HATr) is a challenge for the eradication of Human African Trypansomiaisis (HAT) following the widespread emergence of increased monotherapy drug treatment failures against Trypanosoma brucei gambiense and T. b. rhodesiense that are associated with changes in pathogen receptors. Methods: Electronic searches of 12 databases and 3 Google search websites for human African trypanocide resistance were performed using a keyword search criterion applied to both laboratory and clinical studies. Fifty-one publications were identified and included in this study using the PRISMA checklist. Data were analyzed using RevMan and random effect sizes were computed for the statistics at the 95% confidence interval. Results: Pentamidine/melarsoprol/nifurtimox cross-resistance is associated with loss of the T. brucei adenosine transporter 1/purine 2 gene (TbAT1/P2), aquaglyceroporins (TbAQP) 2 and 3, followed by the high affinity pentamidine melarsoprol transporter (HAPT) 1. In addition, the loss of the amino acid transporter (AAT) 6 is associated with eflornithine resistance. Nifurtimox/eflornithine combination therapy resistance is associated with AAT6 and nitroreductase loss, and high resistance and parasite regrowth is responsible for treatment relapse. In clinical studies, the TbAT1 proportion of total random effects was 68% (95% CI: 38.0−91.6); I2 = 96.99% (95% CI: 94.6−98.3). Treatment failure rates were highest with melarsoprol followed by eflornithine at 41.49% (95% CI: 24.94−59.09) and 6.56% (3.06−11.25) respectively. HATr-resistant phenotypes used in most laboratory experiments demonstrated significantly higher pentamidine resistance than other trypanocides. Conclusion: The emergence of drug resistance across the spectrum of trypanocidal agents that are used to treat HAT is a major threat to the global WHO target to eliminate HAT by 2030. T. brucei strains were largely resistant to diamidines and the use of high trypanocide concentrations in clinical studies have proved fatal in humans. Studies to develop novel chemotherapeutical agents and identify alternative protein targets could help to reduce the emergence and spread of HATr.

Systematic Review and Meta-Analysis on Knowledge Attitude and Practices on African Animal Trypanocide Resistance.

BACKGROUND: African trypanocide resistance is an emerging public health emergency whose control requires a revisit on farmer's knowledge, attitudes, and practices in developing countries. African animal trypanocide resistance (AATr) is rife in an environment where drug use and policy decisions are disjointed. The objective of the study was to identify community factors responsible for the development of AATr. This was important since diminazene aceturate (DA), isometamidium chloride (ISM), and homidium bromide (HB) have existed for over 30 years and no new drugs have been provided to farmers. METHODS: An electronic keyword search across 12 databases was conducted using a search criterion from 1806 to June 2022. This generated a total of 24 publications, but after removing duplicates, review articles, and nonrelated articles, a total of eight papers were included in the analysis by following the PRISMA checklist. A meta-analysis was conducted on the data extracted and the risk ratio and inverse variance at 95% confidence interval were calculated using RevMan®. RESULTS: All the eight articles in the study showed that DA was the most preferred trypanocide in both West and Eastern Africa. Poor farmer knowledge of AATr and limited drug options were major drivers for trypanocide resistance. In addition, farmer treatments, use of untrained personnel, poor administration, poor dosing, and preparation of trypanocides were major drivers for the development of AATr and similarities were identified in DA and ISM practices (P = 0.13). CONCLUSIONS: AATr is spread in developing countries due to a lack of community knowledge, attitudes, and drug-use practices. This situation could be reversed through interdisciplinary collaborations in endemic communities by promoting effective treatments and responsible drug handling.

Molecular survey for tick-borne pathogens and associated risk factors in sheep and goats in Kano Metropolis, Nigeria.

Tick-borne pathogens (TBPs) pose an increased health and productivity risk to livestock in sub-Saharan Africa. Information regarding TBPs infecting small ruminants in Kano metropolis is scarce. Therefore, we investigated the molecular epidemiology of tick-borne pathogens of economic importance from sheep and goats in Kano, Nigeria using Polymerase chain reaction (PCR). A total of 346 blood DNA samples were collected from small ruminants and analyzed for TBPs using PCR and sequencing. Risk of infection was determined for age, sex, breed and animal species. Our results indicate the absence of piroplasmids (Babesia/Theileria) and Rickettsia spp. infections. The overall prevalence for Anaplasma spp. was 9.25% (32/346) with a higher prevalence in goats 13.59% (25/184) compared with sheep 4.32% (7/162). With respect to age of animals, goats >4 years had the highest prevalence of 32.45% (11/37) which differs significantly (P = 0.0059) compared with other age categories. Cross breed goats had a prevalence of 15.63% (5/32) compared with Kano brown breed 14.08 (20/142). Sex significant difference (P = 0.029) was observed in the goats with females having the highest prevalence 20.89% (14/67) compared with males 9.40% (11/117). Furthermore, with regards to sheep, no significant difference (P > 0.05) was observed with respect to age and breed. Finally, no significant difference (P > 0.05) was observed with the prevalence of Anaplasma spp. due to Body condition score (BCS) in both sheep and goats. Conclusively, the occurrence of TBPs in small ruminants is low. Continuous efforts in tick control must be sustained to ensure high productive yield and reduced disease burden associated with TBPs of sheep and goats in Kano metropolis.

An Update on African Trypanocide Pharmaceutics and Resistance.

African trypanosomiasis is associated with Trypanosoma evansi, T. vivax, T. congolense, and T. brucei pathogens in African animal trypanosomiasis (AAT) while T. b gambiense and T. b rhodesiense are responsible for chronic and acute human African trypanosomiasis (HAT), respectively. Suramin sodium suppresses ATP generation during the glycolytic pathway and is ineffective against T. vivax and T. congolense infections. Resistance to suramin is associated with pathogen altered transport proteins. Melarsoprol binds irreversibly with pyruvate kinase protein sulfhydryl groups and neutralizes enzymes which interrupts the trypanosome ATP generation. Melarsoprol resistance is associated with the adenine-adenosine transporter, P2, due to point mutations within this transporter. Eflornithine is used in combination with nifurtimox. Resistance to eflornithine is caused by the deletion or mutation of TbAAT6 gene which encodes the transmembrane amino acid transporter that delivers eflornithine into the cell, thus loss of transporter protein results in eflornithine resistance. Nifurtimox alone is regarded as a poor trypanocide, however, it is effective in melarsoprol-resistant gHAT patients. Resistance is associated with loss of a single copy of the genes encoding for nitroreductase enzymes. Fexinidazole is recommended for first-stage and non-severe second-stage illnesses in gHAT and resistance is associated with trypanosome bacterial nitroreductases which reduce fexinidazole. In AAT, quinapyramine sulfate interferes with DNA synthesis and suppression of cytoplasmic ribosomal activity in the mitochondria. Quinapyramine sulfate resistance is due to variations in the potential of the parasite's mitochondrial membrane. Pentamidines create cross-links between two adenines at 4-5 pairs apart in adenine-thymine-rich portions of Trypanosoma DNA. It also suppresses type II topoisomerase in the mitochondria of Trypanosoma parasites. Pentamidine resistance is due to loss of mitochondria transport proteins P2 and HAPT1. Diamidines are most effective against Trypanosome brucei group and act via the P2/TbAT1 transporters. Diminazene aceturate resistance is due to mutations that alter the activity of P2, TeDR40 (T. b. evansi). Isometamidium chloride is primarily employed in the early stages of trypanosomiasis and resistance is associated with diminazene resistance. Phenanthridine (homidium bromide, also known as ethidium bromide) acts by a breakdown of the kinetoplast network and homidium resistance is comparable to isometamidium. In humans, the development of resistance and adverse side effects against monotherapies has led to the adoption of nifurtimox-eflornithine combination therapy. Current efforts to develop new prodrug combinations of nifurtimox and eflornithine and nitroimidazole fexinidazole as well as benzoxaborole SCYX-7158 (AN5568) for HAT are in progress while little comparable progress has been done for the development of novel therapies to address trypanocide resistance in AAT.

African animal trypanocide resistance: A systematic review and meta-analysis.

Background: African animal trypanocide resistance (AATr) continues to undermine global efforts to eliminate the transmission of African trypanosomiasis in endemic communities. The continued lack of new trypanocides has precipitated drug misuse and overuse, thus contributing to the development of the AATr phenotype. In this study, we investigated the threat associated with AATr by using the major globally available chemotherapeutical agents. Methods: A total of seven electronic databases were screened for an article on trypanocide resistance in AATr by using keywords on preclinical and clinical trials with the number of animals with treatment relapse, days taken to relapse, and resistant gene markers using the PRISMA checklist. Data were cleaned using the SR deduplicator and covidence and analyzed using Cochrane RevMan®. Dichotomous outputs were presented using risk ratio (RR), while continuous data were presented using the standardized mean difference (SMD) at a 95% confidence interval. Results: A total of eight publications in which diminazene aceturate (DA), isometamidium chloride (ISM), and homidium chloride/bromide (HB) were identified as the major trypanocides were used. In all preclinical studies, the development of resistance was in the order of HB > ISM > DA. DA vs. ISM (SMD = 0.15, 95% CI: -0.54, 0.83; I 2 = 46%, P = 0.05), DA vs. HB (SMD = 0.96, 95% CI: 0.47, 1.45; I 2 = 0%, P = 0.86), and HB vs. ISM (SMD = -0.41, 95% CI: -0.96, 0.14; I 2 = 5%, P = 0.38) showed multiple cross-resistance. Clinical studies also showed evidence of multi-drug resistance on DA and ISM (RR = 1.01, 95% CI: 0.71-1.43; I 2 = 46%, P = 0.16). To address resistance, most preclinical studies increased the dosage and the treatment time, and this failed to improve the patient's prognosis. Major markers of resistance explored include TbAT1, P1/P2 transporters, folate transporters, such as F-I, F-II, F-III, and polyamine biosynthesis inhibitors. In addition, immunosuppressed hosts favor the development of AATr. Conclusion: AATr is a threat that requires a shift in the current disease control strategies in most developing nations due to inter-species transmission. Multi-drug cross-resistance against the only accessible trypanocides is a major public health risk, justifying the need to revise the policy in developing countries to promote control of African trypanosomiasis.

Correction: Mathematical modelling and control of African animal trypanosomosis with interacting populations in West Africa-Could biting flies be important in maintaining the disease endemicity?

[This corrects the article DOI: 10.1371/journal.pone.0242435.].

A Descriptive-Multivariate Analysis of Community Knowledge, Confidence, and Trust in COVID-19 Clinical Trials among Healthcare Workers in Uganda.

Background-misinformation and mistrust often undermines community vaccine uptake, yet information in rural communities, especially of developing countries, is scarce. This study aimed to identify major challenges associated with coronavirus disease 2019 (COVID-19) vaccine clinical trials among healthcare workers and staff in Uganda. Methods-a rapid exploratory survey was conducted over 5 weeks among 260 respondents (66% male) from healthcare centers across the country using an online questionnaire. Twenty-seven questions assessed knowledge, confidence, and trust scores on COVID-19 vaccine clinical trials from participants in 46 districts in Uganda. Results-we found low levels of knowledge (i.e., confusing COVID-19 with Ebola) with males being more informed than females (OR = 1.5, 95% CI: 0.7-3.0), and mistrust associated with policy decisions to promote herbal treatments in Uganda and the rushed international clinical trials, highlighting challenges for the upcoming Oxford-AstraZeneca vaccinations. Knowledge, confidence and trust scores were higher among the least educated (certificate vs. bachelor degree holders). We also found a high level of skepticism and possible community resistance to DNA recombinant vaccines, such as the Oxford-AstraZeneca vaccine. Preference for herbal treatments (38/260; 14.6%, 95% CI: 10.7-19.3) currently being promoted by the Ugandan government raises major policy concerns. High fear and mistrust for COVID-19 vaccine clinical trials was more common among wealthier participants and more affluent regions of the country. Conclusion-our study found that knowledge, confidence, and trust in COVID-19 vaccines was low among healthcare workers in Uganda, especially those with higher wealth and educational status. There is a need to increase transparency and inclusive participation to address these issues before new trials of COVID-19 vaccines are initiated.

Molecular epidemiology of anaplasmosis in small ruminants along a human-livestock-wildlife interface in Uganda.

BACKGROUND: Information as regards the epidemiology of the Anaplasmataceae in small ruminants in several low- and middle-income countries is scarce. METHODS: In this study a total of 712 DNA samples collected from small ruminants were analyzed for Anaplasmataceae and Anaplasma ovis using the 16S rRNA and MSP4 genes respectively. Infection risk was assessed by location, sex and age of the animals and qGIS® was used to construct spatial maps. RESULTS: The prevalence of Anaplasmataceae spp was 89.1% (95% CI: 77.5-95.9) and 79.1% (95% CI: 75.9-82.1) in ovines and caprines respectively (RR = 1.1, 95% CI: 1.0-1.3); higher than those previously reported in other eastern African countries. The prevalence of A. ovis was 26.1% and 25.4% for both ovines and caprines respectively with ovines showing significantly higher levels of infection than caprines (P < 0.05). The risk of Anaplasma ovis infections was not affected by age (OR = 1.2, 95% CI: 0.9-1.7) or sex (OR = 1.1, 95% CI: 0.6-2.0). Small ruminants located at the forest edge (<0.3 km) showed higher A. ovis prevalence than those found inland with infections present in the midland regions associated with increased agricultural activity. CONCLUSION: Anaplasma ovis remains a major challenge for small ruminant husbandry in Uganda and infections are under-reported. Policy efforts to prioritize management of Anaplasmataceae for small ruminant health would promote livestock productivity in vulnerable communities, improving livelihoods and ecosystem health.

Morphological, Molecular Identification and Distribution of Trypanosome-Transmitting Dipterans from Cattle Settlements in Southwest Nigeria.

INTRODUCTION: Glossina spp. (Glossinidae), Tabanus spp. (Tabanidae), Ancala spp. (Tabanidae), Atylotus spp. (Tabanidae) and Stomoxys spp. (Muscidae) are important transmitting vectors of African animal trypanosomosis in sub-Saharan Africa. There is paucity of information on the distribution and identification of these flies in cattle settlements in southwest Nigeria. METHODS: The distribution patterns, genetic variations and diversities of dipteran flies in southwest Nigeria were described and identified using morphological and molecular analysis of the 28S rDNA gene. RESULTS: Of the 13,895 flies examined morphologically between April 2016 and March 2017, tabanids were identified [Tabanus (0.34%), Ancala (0.03%), Atylotus (0.01%), Haematopota (0.014%) and Chrysops (0.11%)]. Two stomoxyine species were identified; Stomoxys niger niger Macquart (45.30%) and Stomoxys calcitrans Linnaeus (17.29%) and two Glossina spp. namely; Glossina p. gambiense Vanderplank, 1911 (0.46%) and Glossina tachinoides Westwood (0.51%) were identified. The identities were further confirmed in a BLAST search using their nucleotide sequences. The median-joining network of the 28S rDNA gene sequences indicated that fly species examined were genetically distinct. The apparent density of all the trapped flies was highest at a mean temperature of 26-28 â„ƒ, humidity > 80% and rainfall of 150-220 mm/month. The distribution of flies was observed to increase as vegetation increased in density and decreased in areas with relatively high human population density (> 100/km2). CONCLUSIONS: The population indices of the 28S rDNA gene of the flies suggest that analysis of nuclear DNA fragments may provide more information on the molecular ecology of these flies. Characterising fly species and assessing their impact are essential in distribution and monitoring AAT spread.

Mathematical modelling and control of African animal trypanosomosis with interacting populations in West Africa-Could biting flies be important in main taining the disease endemicity?

African animal trypanosomosis (AAT) is transmitted cyclically by tsetse flies and mechanically by biting flies (tabanids and stomoxyines) in West Africa. AAT caused by Trypanosoma congolense, T. vivax and T. brucei brucei is a major threat to the cattle industry. A mathematical model involving three vertebrate hosts (cattle, small ruminants and wildlife) and three vector flies (Tsetse flies, tabanids and stomoxyines) was described to identify elimination strategies. The basic reproduction number (R0) was obtained with respect to the growth rate of infected wildlife (reservoir hosts) present around the susceptible population using a next generation matrix technique. With the aid of suitable Lyapunov functions, stability analyses of disease-free and endemic equilibria were established. Simulation of the predictive model was presented by solving the system of ordinary differential equations to explore the behaviour of the model. An operational area in southwest Nigeria was simulated using generated pertinent data. The R0 < 1 in the formulated model indicates the elimination of AAT. The comprehensive use of insecticide treated targets and insecticide treated cattle (ITT/ITC) affected the feeding tsetse and other biting flies resulting in R0 < 1. The insecticide type, application timing and method, expertise and environmental conditions could affect the model stability. In areas with abundant biting flies and no tsetse flies, T. vivax showed R0 > 1 when infected wildlife hosts were present. High tsetse populations revealed R0 <1 for T. vivax when ITT and ITC were administered, either individually or together. Elimination of the transmitting vectors of AAT could cost a total of US$ 1,056,990 in southwest Nigeria. Hence, AAT in West Africa can only be controlled by strategically applying insecticides targeting all transmitting vectors, appropriate use of trypanocides, and institutionalising an appropriate barrier between the domestic and sylvatic areas.

Suspected resistance of Trypanosoma species to diminazene aceturate on a cattle farm in Nigeria.

African animal trypanosomiasis is a major cause of mortality and economic losses for the livestock industry in Nigeria. Chemotherapy has been the most reliable option for cattle herders, and the most commonly found drug on the market is diminazene aceturate. To ascertain the long-term efficacy of this compound, we sampled a cattle herd in Ogun State, Nigeria, 2 months after they were treated with diminazene aceturate. The ITS-PCR results revealed 19 positives for trypanosome DNA out of the 79 samples tested (24.1%, 95% CI 16.0-34.5). Seventeen out of the total 19 positives were Trypanosoma congolense (21.5%, 95% CI 13.9-31.8). Mixed infections were also observed. Therefore, the persistence of bovine trypanosomiasis at this Nigerian cattle farm despite treatment could be due to diminazene aceturate resistant trypanosomes being present in the herd.

Endosymbionts interaction with trypanosomes in Palpalis group of Glossina captured in southwest Nigeria.

Glossina species epidemiological studies were conducted in "fly-belt" endemic zone of southwest Nigeria. Two major study areas were identified and four Nzi traps were set in each site for tsetse collection. This study was conducted to determine the prevalence of endosymbionts (Wigglesworthia glossinidia, Sodalis glossinidius and Wolbachia) in natural field-trapped populations of G. p. palpalis and G. tachinoides and investigate the corresponding interactions with African trypanosomes. A total of 64 tsetse flies were collected, these included G. p. palpalis (n = 28) and G. tachinoides (n = 36). Trypanosome infection and endosymbionts of these flies were determined using polymerase chain reaction (PCR) amplification. The infection rates of W. glossinidia was 100.0% in both species, no flies were positive for Wolbachia. Sodalis glossinidius prevalence was similar between the two-tsetse species, with G. p. palpalis and G. tachinoides showing prevalence of 35.7% (95%CI: 20.7-54.2) and 27.8% (95%CI: 15.9-44.0) respectively. No relationship was found between the endosymbionts and trypanosomes in trapped tsetse flies. More studies are needed to enhance the potential control interventions mediated by endosymbionts to reduce parasitic infections.

Molecular identification of bovine trypanosomes in relation to cattle sources in southwest Nigeria.

Bovine trypanosomosis is a problem in the livestock industry in Nigeria. A longitudinal survey of cattle sampled during the wet and dry seasons was conducted from April 2016 to March 2017. Blood samples were collected by random sampling from 745 cattle in southwest Nigeria and screened for trypanosomes by internal transcribed spacer-polymerase chain reaction (ITS-PCR). Cattle positive for Trypanozoon DNA were further screened with the Rode Trypanozoon antigen type (RoTat) 1.2 PCR and Trypanosoma brucei gambiense glycoprotein (TgsGP) genes for T. evansi and T. b. gambiense respectively. Trypanosome DNA was amplified in 23.8% (95%CI: 20.8-26.9) of cattle with significantly higher prevalence in wet season (95%CI: 22.9-30.8) when compared to the dry season (95%CI: 14.3-23.6). A high prevalence was observed in Fulani cattle farms 54.1% (95%CI: 42.78-64.93%) while the prevalence was lower in institutional farms 14.7% (95%CI: 10.10-20.97%). Trypanosoma vivax was the most prevalent trypanosome observed (11.54% (95%CI: 9.44-14.04%)), followed by T. congolense 8.5% (95%CI: 6.67-10.67%) T. b. brucei 4.8% (95%CI: 3.51-6.62%) and T. evansi 1.74% (95%CI: 1.02-2.96%). Mixed infections were observed in 2.8% (95%CI: 1.85-4.27%) of cattle. Seasonal variation revealed a predominance of T. congolense and T. vivax in wet and dry season, respectively. The high prevalence of Trypanosoma species in cattle indicates a need for expanded surveillance for AAT in southwest Nigeria. Migration, settlement patterns, increased marketing and management types were some of the risk factors identified for AAT.

Practices of cattle keepers of southwest Nigeria in relation to bovine trypanosomosis.

Significant increases in human and livestock populations coupled with agricultural practices have changed the socioeconomic perspectives of livestock diseases. Evaluating the socioeconomic impact of bovine trypanosomosis and its vectors (Glossina, Tabanus and Stomoxys) from the perspective of the livestock owners is of great significance. Participatory rural appraisal was conducted among 209 livestock owners (focus groups) to determine the behavioural practices of animal husbandary to bovine trypanosomosis. In Nigeria, common Trypanosoma species found in cattle are Trypanosoma vivax, Trypanosoma congolense and Trypanosoma brucei. Trypanosomosis peaks were reported by owners to be in the months of March-August. A total of 70.8% (95%CI 64.32-76.56%) cattle owners perceived trypanosomosis as a major disease in their herd, 13.4% (95%CI 9.43-18.68%) practiced transhumance in the wet season and 93.9% (95%CI 88.58-96.92%) make use of trypanocides, and approximately US$ 8.4 million is spent annually on trypanocides in southwest Nigeria livestock industry. About 60.5% (95%CI 51.84-68.48) make use of insecticides against transmitting vectors, and only 1.9% (95%CI 0.75-4.82%) have ever heard of any form of government intervention scheme. Estimated losses ≥ US$ 426 (80-100% loss) can be incurred on a single animal depending on the size and market value. There is significant increase (16.2%, 95%CI 11.15-23.00%, P < 0.05) in the mortality rate of bovine trypanosomosis when compared to other livestock diseases. It will therefore be useful to involve the livestock owners with devising new and integrated measures for reducing the impact of this trypanosomosis.

Bovine and small ruminant African animal trypanosomiasis in Nigeria - A review.

Despite extensive attempts over many decades to control African Animal Trypanosomiasis (AAT) across the tsetse fly belt of Nigeria, AAT persists as major animal health problem causing severe morbidity and mortality in livestock. The large agricultural losses in turn have severe adverse impacts on sustainable agricultural development. Despite this, in the past 50 years there have been no significant national control programs against AAT. This review explores the history of AAT control in Nigeria, examining the successes and failures in measures adopted in Nigeria to control AAT and the changing disease epidemiology.

Apoptotic markers in protozoan parasites.

The execution of the apoptotic death program in metazoans is characterized by a sequence of morphological and biochemical changes that include cell shrinkage, presentation of phosphatidylserine at the cell surface, mitochondrial alterations, chromatin condensation, nuclear fragmentation, membrane blebbing and the formation of apoptotic bodies. Methodologies for measuring apoptosis are based on these markers. Except for membrane blebbing and formation of apoptotic bodies, all other events have been observed in most protozoan parasites undergoing cell death. However, while techniques exist to detect these markers, they are often optimised for metazoan cells and therefore may not pick up subtle differences between the events occurring in unicellular organisms and multi-cellular organisms.In this review we discuss the markers most frequently used to analyze cell death in protozoan parasites, paying special attention to changes in cell morphology, mitochondrial activity, chromatin structure and plasma membrane structure/permeability. Regarding classical regulators/executors of apoptosis, we have reviewed the present knowledge of caspase-like and nuclease activities.

Factors affecting trypanosome maturation in tsetse flies.

Trypanosoma brucei brucei infections which establish successfully in the tsetse fly midgut may subsequently mature into mammalian infective trypanosomes in the salivary glands. This maturation is not automatic and the control of these events is complex. Utilising direct in vivo feeding experiments, we report maturation of T. b. brucei infections in tsetse is regulated by antioxidants as well as environmental stimuli. Dissection of the maturation process provides opportunities to develop transmission blocking vaccines for trypanosomiasis. The present work suggests L-cysteine and/or nitric oxide are necessary for the differentiation of trypanosome midgut infections in tsetse.