Farmer perceptions and willingness to pay for novel livestock pest control technologies: A case of tsetse repellent collar in Kwale County in Kenya

Tsetse-transmitted Animal African Trypanosomosis (AAT) is one of the most important constraints to livestock development in Africa. Use of trypanocides has been the most widespread approach for the management of AAT, despite the associated drug resistance and health concerns associated with drug metabolites in animal products. Alternative control measures that target tsetse fly vectors of AAT, though effective, have been hard to sustain in part because these are public goods applied area-wide. The International Centre of Insect Physiology and Ecology (icipe) and partners have developed and implemented a novel tsetse repellent collar (TRC) applied on animals to limit contact of tsetse flies and livestock, thereby reducing AAT transmission. The TRC has now advanced to commercialization. A household-level survey involving 632 cattle keeping households, was conducted in Shimba Hills region of Kwale County, where field trials of the TRC have been previously conducted to assess farmers’ knowledge, perception, and practices towards the management of tsetse flies, their willingness to pay (WTP) for the TRC, and factors affecting the WTP. Almost all the respondents (90%) reported that tsetse flies were the leading cattle infesting pests in the area. About 22% of these correctly identified at least four AAT clinical signs, and even though many (68%) used trypanocidal drugs to manage the disease, 50% did not perceive the drug as being effective in AAT management (50%). Few respondents (8%) were aware of the harmful effects of trypanocidal drugs. About 89% of the respondents were aware of icipe TRC, and 30% of them were using the field trial collars during the survey. Sixty-three (63%) of them were willing to pay for the TRC at the same cost they spend treating an animal for AAT. On average farmers were willing to pay KES 3,352 per animal per year. Male educated household heads are likely to pay more for the TRC. Moreover, perceived high AAT prevalence and severity further increases the WTP. Wider dissemination and commercialization of the herd-level tsetse control approach (TRC) should be encouraged to impede AAT transmission and thus enhance food security and farm incomes among the affected rural communities. Besides the uptake of TRC can be enhanced through training, especially among women farmers.

AQPX-cluster aquaporins and aquaglyceroporins are asymmetrically distributed in trypanosomes

Major Intrinsic Proteins (MIPs) are membrane channels that permeate water and other small solutes. Some trypanosomatid MIPs mediate the uptake of antiparasitic compounds, placing them as potential drug targets. However, a thorough study of the diversity of these channels is still missing. Here we place trypanosomatid channels in the sequence-function space of the large MIP superfamily through a sequence similarity network. This analysis exposes that trypanosomatid aquaporins integrate a distant cluster from the currently defined MIP families, here named aquaporin X (AQPX). Our phylogenetic analyses reveal that trypanosomatid MIPs distribute exclusively between aquaglyceroporin (GLP) and AQPX, being the AQPX family expanded in the Metakinetoplastina common ancestor before the origin of the parasitic order Trypanosomatida. Synteny analysis shows how African trypanosomes specifically lost AQPXs, whereas American trypanosomes specifically lost GLPs. AQPXs diverge from already described MIPs on crucial residues. Together, our results expose the diversity of trypanosomatid MIPs and will aid further functional, structural, and physiological research needed to face the potentiality of the AQPXs as gateways for trypanocidal drugs.

In Vitro and In Vivo Trypanocidal Efficacy of Synthesized Nitrofurantoin Analogs

African trypanosomes cause diseases in humans and livestock. Human African trypanosomiasis is caused by Trypanosoma brucei rhodesiense and T. b. gambiense. Animal trypanosomoses have major effects on livestock production and the economy in developing countries, with disease management depending mainly on chemotherapy. Moreover, only few drugs are available and these have adverse effects on patients, are costly, show poor accessibility, and parasites develop drug resistance to them. Therefore, novel trypanocidal drugs are urgently needed. Here, the effects of synthesized nitrofurantoin analogs were evaluated against six species/strains of animal and human trypanosomes, and the treatment efficacy of the selected compounds was assessed in vivo. Analogs 11 and 12, containing 11- and 12-carbon aliphatic chains, respectively, showed the highest trypanocidal activity (IC50 < 0.34 µM) and the lowest cytotoxicity (IC50 > 246.02 µM) in vitro. Structure-activity relationship analysis suggested that the trypanocidal activity and cytotoxicity were related to the number of carbons in the aliphatic chain and electronegativity. In vivo experiments, involving oral treatment with nitrofurantoin, showed partial efficacy, whereas the selected analogs showed no treatment efficacy. These results indicate that nitrofurantoin analogs with high hydrophilicity are required for in vivo assessment to determine if they are promising leads for developing trypanocidal drugs.

A systematic review of historical and current trends in Chagas disease

Introduction: Chagas disease (CD) is caused by Trypanosoma cruzi. When acquired, the disease develops in stages. For diagnosis, laboratory confirmation is required, and an extensive assessment of the patient’s health should be performed. Treatment consists of the administration of trypanocidal drugs, which may cause severe adverse effects. The objective of our systematic review was to analyze data contained in the CD published case reports to understand the challenges that patients and clinicians face worldwide. Materials and methods: We performed a systematic review following the PRISMA guidance. PubMed database was explored using the terms ‘American trypanosomiasis’ or ‘Chagas disease’. Results were limited to human case reports written in English or Spanish. A total of 258 reports (322 patients) were included in the analysis. Metadata was obtained from each article. Following this, it was analyzed to obtain descriptive measures. Results: From the sample, 56.2% were males and 43.8% were females. Most cases were from endemic countries (85.4%). The most common clinical manifestations were fever during the acute stage (70.0%), dyspnea during the chronic stage in its cardiac form (53.7%), and constipation during the chronic stage in its digestive form (73.7%). Most patients were diagnosed in the chronic stage (72.0%). Treatment was administered in 56.2% of cases. The mortality rate for the acute stage cases was 24.4%, while for the chronic stage this was 28.4%. Discussion: CD is a parasitic disease endemic to Latin America, with increasing importance due to human and vector migration. In this review, we report reasons for delays in diagnosis and treatment, and trends in medical practices. Community awareness must be increased to improve CD’s diagnoses; health professionals should be appropriately trained to detect and treat infected individuals. Furthermore, public health policies are needed to increase the availability of screening and diagnostic tools, trypanocidal drugs, and, eventually, vaccines.

Trypanotolerance Sheko cattle: an option for sustainable control of bovine trypanosomiasis

Trypanosomiasis is an impediment to cattle production and other agricultural development in tsetse-infested areas. It is a severe parasitic disease that causes loss in the production and performance of cattle. Hence, the aim of this paper is to review trypanosomiasis control options with emphasis on the use of trypanotolerant Sheko cattle breed for sustainable management of bovine trypanosomiasis in tsetse infested areas. Several methods have been used to control trypanosomiasis through the use of trypanocidal drugs and the management of the vector, tsetse fly. Tsetse fly controls require expensive insecticides and have adverse environmental consequences. Trypanocidal drugs are commonly used and considered a practical trypanosomiasis control method. However, the rise in trypanocidal drug resistance has rendered this option ineffective. The possibility of developing and using a vaccine against trypanosomiasis currently remains out of reach as Trypanosoma periodically undergo antigenic variation. In the absence of a vaccine, presence of trypanocidal drug resistance, and the lack of sustainable tsetse fly control measures demand the need to use trypanotole-rant cattle breeds. The Sheko breed which is found only in southwestern Ethiopia displays considerable natural resistance to tsetse-transmitted trypanosomiasis. This genetic resource provides sustainable solution for challenges related to trypanosomiasis. These cattle have a low level of parasitemia and are able to maintain a good packed cell volume (PCV) compared to other indigenous breeds. As several trypanosomiasis control methods are ineffective, the use of trypanotolerance cattle like Sheko breed in tsetse-fly-challenged areas was suggested.

Detection of Trypanosoma vivax in tissues of experimentally infected goats: what is the role of adipose tissue in the life cycle of this protozoon?

Trypanosomiasis, caused by Trypanosoma vivax, is responsible for great economic losses among livestock in Africa and South America. During the life cycle of these parasites, they may present different morphological, metabolic and physiological characteristics depending on the interactions that are encountered at each point of their life cycle. Although T. vivax is frequently reported in the circulation of its mammalian hosts, it has the ability to migrate to the tissues of these individuals. However, this characteristic is poorly understood. In this context, we aimed to investigate the presence of T. vivax and the changes caused in different tissues of experimentally infected goats. Despite the animals were not perfused before tissues collection, using different approaches, we demonstrated its presence in different samples, including in the adipose tissue and skin of infected animals. In addition, a mononuclear inflammatory reaction, mostly characterized by an infiltrate of lymphocytes, plasma cells and macrophages were observed. The results highlight the possibility that, like other trypanosomatids, T. vivax may use these tissues during its life cycle. Future studies aiming to elucidate the length of time for which T. vivax remains active in these sites, and whether it uses these sites as a refuge from trypanocidal drugs, and whether it is capable of recolonizing the blood circulation, are much needed.

Trypanocidal drug utilization practices in tsetse suppression and non-suppression areas of South Omo Zone, Southwestern Ethiopia

Trypanosomosis control in Ethiopia is largely rely on use of available trypanocidal drugs although there are other options such as vector control and use of trypanotolerant hosts. A cross-sectional survey aimed at assessing the knowledge, attitude and practices of trypanocidal drug utilization and constraints of trypanosome infection conducted in tsetse suppression and non-suppression areas of South Omo Zone, Ethiopia. The questionnaire based survey was conducted from November 2018 to May 2019. Descriptive statistics was used to summarize the field data obtained from 184 cattle owners. Sixty (60) of the cattle owners were from suppression area and 124 from tsetse non-suppression area. Accordingly, draft oxen and milking cows respectively from tsetse suppression and non-suppression areas were classes of animals which were given priority in trypanocidal drug treatment. About 79.03% and 81.7% of cattle owners respectively from tsetse suppression and non-suppression areas witnessedthat they treat their sick animals by themselves; indicating that veterinarians and other animal health experts have very little role in medication of sick animals. Diminazine aceturate (DA) was the main trypanocidal drug preferred by cattle owners in tsetse suppression area while both DA and Isometamidium chloride (ISM) were used in non-suppression areas. About 83.1% of the respondents from tsetse suppression areas and 86.7% from non-suppression area reported treatment failures following the use of trypanocidal drugs. Moreover, about 79.61% and 86.53% of respondents respectively from tsetse suppression and non-suppression areas observed that drugs obtained from private drug stores were less effective compared to drugs obtained from governmental veterinary clinics. Furthermore, the respondents disclosed that DA was the most horrible trypanocidal drug in showing treatment failures despite high preference by cattle owners. It was also noted that treatment frequency was higherin tsetse suppression areas than non-suppression areas regardless of vector suppression campaign. In conclusion, higher dependency of cattle owners on trypanocidal drugs, limited trypanocidal drug availability in the veterinary pharmaceutical market, frequent trypanocidal drug usage and injection by unskilled herdsmen and owners report on trypanocidal drug treatment failures may point out the issue of trypanocidal drug resistance in the area. Therefore, awareness creation to livestock owners on the effect of misuse of trypanocidal drugs and safe trypanocidal drug usage policy should be put into effect to uphold the effectiveness of currently available trypanocidal drugs. Keywords: Trypanosomosis; Trypanocidal Drugs; Tsetse suppression; South Omo Zone; Ethiopia