Animal African Trypanosomiasis in Nigeria: A long way from elimination/ eradication

Acta Tropica 176 (2017) 323–331 Contents lists available at ScienceDirect Acta Tropica journal homepage: www.elsevier.com/locate/actatropica Review Animal African Trypanosomiasis in Nigeria: A long way from elimination/ eradication MARK C. Isaaca, J.A. Ohioleia, , F. Ebhodagheb, I.B. Igbinosaa, A.A. Ezec ⁎ a b c Department of Zoology, Ambrose Alli University, Ekpoma, Nigeria African Regional Postgraduate Programme in Insect Science, West African Sub-Regional Centre, University of Ghana, Legon-Accra, Ghana Department of Medical Biochemistry, College of Medicine, University of Nigeria, Enugu Campus, Enugu, Nigeria A R T I C L E I N F O A B S T R A C T Keywords: Animal African Trypanosomiasis (AAT) Livestock The progressive control pathway (PCP) Nigeria Animal African Trypanosomiasis (AAT) is a disease of livestock that directly hinders livestock production and therefore impedes the socio-economic development of sub-Saharan Africa. The establishment of the Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) was to enhance the goal of elimination and eradication of tsetse flies and AAT from endemic countries in Africa. In order to achieve AAT eradication, a five-step progressive control pathway (PCP) model has been proposed. The data presented in this report demonstrates that Nigeria is highly endemic of AAT and that it is yet to comprehensively approach the process of eradication as it is at the infancy stage of data gathering and processing. This review is thus presented to serve as a wake-up call to all relevant stakeholders to intensify efforts in approaching the painstaking process of AAT eradication in Nigeria. 1. Introduction Animal African Trypanosomiasis (AAT) is a disease of livestock caused by trypanosomes and cyclically transmitted by tsetse flies. The disease brings with it huge annual economic losses (Dede et al., 2007). The impact of AAT on a community is the result of complex interactions between environmental, political, socio-cultural, entomological and livestock management factors (Bouyer et al., 2013). It was recently estimated that Nigeria has 19.5 million cattle, 72.5 million goats, 41.3 million sheep, 7.1 million pigs, 28,000 camels and 974, 499 donkeys (National Agriculture Sample Survey, Nigeria, 2010). However, majority of these livestock are at risk of AAT because they are located in tsetse-infested regions. Infection with AAT may result in weakness, lethargy, weight loss, anaemia and sometimes death of the animal. Control efforts against AAT in Africa have been employed on isolated bases and hence identified as an impediment to effective control because of trans-boundary transmission. Thus, the need for a concerted effort was proposed and this berthed the Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) programme with the mandate of fostering the elimination of tsetse and trypanosomiasis from the African continent (Kabayo, 2002). For PATTEC-Nigeria to strategically approach elimination/eradication, it has to constantly update information on AAT in relation to parasite’s infection rate in livestock, parasite’s prevalence in the vectors, tsetse distribution and applied diagnostic methods. Parts of these data are presented in this report, while the challenges of AAT elimination and eradication are discussed. The progressive control pathway (PCP) is a model that captures the sequence of events that should be rigorously followed before tsetse and AAT elimination/eradication can be achieved (Diall et al., 2017). There are five PCP stages: the first requires the development of a national atlas on tsetse and AAT, while the second is characterised by employing methods that should bring about reduction in tsetse density and AAT burden. Others involve creating sustainable AAT free areas after successful application of appropriate integrated methods in endemic locations. Thus, within the PCP model, it is imperative that AAT endemic countries regularly appraise control efforts and other activities so as to precisely identify its stage in the AAT eradication plan as presented for Nigeria in this report. 1.1. Tsetse distribution, density and infection rate Nigeria occupies 923,768 km2 with 36 states and the Federal Capital Territory (FCT), Abuja. These states which are comprised of local government areas are further clustered into six geopolitical zones (North-Central, North-East, North-West, South-South, South-East, and South-West) (see Fig. 1). The rainfall pattern is such that the north Corresponding author. E-mail addresses: cle21200@gmail.com (C. Isaac), asekhaenj@gmail.com (J.A. Ohiolei), fiebhodaghe@st.ug.edu.gh (F. Ebhodaghe), igbinosa202@yahoo.com (I.B. Igbinosa), anthonious.eze@unn.edu.ng (A.A. Eze). ⁎ http://dx.doi.org/10.1016/j.actatropica.2017.08.032 Received 1 August 2017; Received in revised form 18 August 2017; Accepted 26 August 2017 0001-706X/ © 2017 Elsevier B.V. All rights reserved. Acta Tropica 176 (2017) 323–331 C. Isaac et al. Fig. 1. Map of Nigeria indicating areas of AAT survey on livestock. dense mangrove forests of the Niger Delta and the rain forests of the south to the dry grassland of the north. About 70% of Nigeria landmass is infested with eleven Glossina species (Jordan, 1961) with four (G. palpalis palpalis, G. tachinoides, G. morsitans submorsitans and G. longipalpis) commonly seen (Federal Ministry of Agriculture, 1981; Onyiah, 1995). Nigeria tsetse map showed the occurrence of G. m. submorsitans in a series of discontinuous belt across the northern region, while G. longipalpis are over a wide area in central and south-western Nigeria. Glossina palpalis and G. tachinoides occur across all geopolitical zones but absent from the extreme Northeast areas with only G. tachinoides seen in limited areas on the southern boundary (Onyiah et al., 1983). As a result of the rise in human population and consequent increase in human activities, significant changes in the availability of suitable habitat and hosts that potentially ensure tsetse survival and sustenance in a given location may have occurred with time (Dede et al., 2007). receives less rainfall with much shorter wet season than the south. In addition, Nigeria could be zoned latitudinally into: Guinea (majorly South: 8°N) [Lagos, Oyo, Ekiti, Osun, Ondo, Edo, Delta, Bayelsa, Abia, Ebonyi, Anambra, Rivers, Imo, Enugu, Cross River, Akwa Ibom states]; Savanna [Plateau, Kaduna, Bauchi, Kwara, Niger, Nassawara, Taraba, Adamawa, Gombe, Benue and Kogi states with Abuja (8–11°N)]; and Sahel (extreme North: 11–16°N) [Kebbi, Sokoto, Zamfara, Katsina, Kano, Jigawa, Borno, Gombe and Yobe states] (Omotosho and Abiodun, 2007). Annual rainfall ranges from 1400 to 2700 mm in the Guinean zone, 950–1400 mm (Savanna zone) and 450–1050 mm (Sahelian zone) (Ogungbenro and Morakinyo, 2014). Monthly rainfall pattern is monomodal for Savanna and Sahel and bi-modal for Guinea. Agriculturally sufficient rainfall starts in Nigeria in April peaking between August and September in Sahel and Savanna; while in Guinea, the first peak is in July followed by a short dry break in August, then a second peak in September. The dominant vegetation types range from the 324 Acta Tropica 176 (2017) 323–331 C. Isaac et al. revisit the SIT programme; but before this exercise can be effective and successful, the tsetse species composition, density and distribution have to be reliably investigated across the country. By molecularly identifying tsetse and establishing the degree of isolation and related risk of reinvasion, the tsetse target population are to be divided into partially isolated subunits in which evidence-based decision on the most appropriate control strategy is made for each subunit (Challier et al., 1983; Gooding et al., 2004; Adam et al., 2014; Pagabeleguem et al., 2016). Furthermore, the profiling of cryptic species across locations where SIT could be applied is thus a necessity as this would inform on the vector-complementary strategy because sometimes differences in the feeding preference and trap-avoidance behaviour do occur within subspecies (Simo et al., 2008; Cordon-Obras et al., 2014). Also, areas that were previously tsetse-free or reclaimed may now be tsetse-infested or reinvaded. For instance, erstwhile tsetse-free regions in Jos (North-Central), Obudu (South-South), Mambilla (North-East) and Kano (North-West) are presently tsetse-infested (Kalu, 1992; Fajinmi et al., 2011; Majekodunmi et al., 2013). Recently, there have been pockets of tsetse surveys in northern Nigeria (Ahmed, 2004; Ajibade and Agbede, 2008; Okoh et al., 2011; Obaloto et al., 2015; Abubakar et al., 2016; Isaac et al., 2016; Karshima et al., 2016a) and scantily in the south (Ogedegbe and Rotimi, 2006; Oyekwelu et al., 2017), but the most comprehensive was carried out in Jigawa state (North-East). No tsetse was trapped rather some biting flies that are known mechanical transmitters of trypanosomes (Dede et al., 2013). Similarly, in parts of Gombe (North-East), T. vivax was isolated from livestock without recovery of tsetse in the area but some other biting insects (Usman et al., 2008). Generally, in Nigeria, non-tsetse transmitted trypanosomiasis prevalence is about 27%, higher than some other AAT-endemic countries like Mauritania (24%), Ethiopia (21%) and India (22%) (Losos, 1980; Dia et al., 1997; Pathak et al., 1993; Zeleke and Bekele, 2001). There are several reports suggesting transmission of AAT by non-tsetse biting flies in the northern part of the country (Maxie et al., 1979; Abenga et al., 2004; Dede et al., 2005; Samdi et al., 2011; Obaloto et al., 2015; Abubakar et al., 2016). The only report from the South was in Edo state where parasites of rodents were profiled and results showed the presence of Trypanosoma in two foci (Ekpoma and Sapele Road) with fleas being the likely mechanical transmitters (unpublished data). This brings to fore the need to factor-in other mechanical transmitters of trypanosomes in the fight against AAT. Furthermore, current information on tsetse density and infection rate in known tsetse-infested areas could be useful in the future application of sterile insect technique (SIT) as greater efficiency is attained when low fly density is recorded in an area (Bouyer et al., 2010). Apparent fly density in Yankari, Bauchi state was 70.68 flies/trap/day for G. tachinoides while 5.5 flies/trap/day for G. m. submorsitans (Abubakar et al., 2016) with Gashaka Gumti National Park,Taraba state (NorthEast) recording 26.34 flies/trap/day for all species of tsetse. Meanwhile, a 4.5flies/trap/day was reported in Benue state (Karshima et al., 2016a) while Kamuku National Park had very low density of 0.1fly/ trap/day. Very few surveys with varying results on tsetse infection rate using molecular diagnostic tool have been documented for Nigeria in Yankari, Bauchi state (North-East), Wuya, Kaduna state (North-West) and Benue state (North-Central) (Karshima et al., 2016a; Isaac et al., 2016; Karshima et al., 2016b). Clearly, data in this regard are lacking in most parts of Nigeria; hence the need for a comprehensive national survey using highly sensitive and species/subspecies-specific molecular methods is inevitable as this would ensure an updated national atlas for an effective execution of AAT-control programme. 1.3. Trypanosomiasis in livestock The importance of trypanosomiasis in Nigeria especially to livestock has been recognized in the wake of the 20th century. As soon as the disease started to cause the death of livestock and consequent economic losses, the defunct West African Institute for Trypanosomiasis Research (WAITR) in 1947 now known as Nigerian Institute for Trypanosomiasis Research (NITR) in Kaduna (North-West) was established to conduct research and development for the control and eradication of trypanosomiasis in all geo-ecological zones. It has been estimated that the presence of AAT reduces the total number of livestock in an area by between 25% and 50% (Kristjanson et al., 1999). It has also been predicted that with an output elasticity of 0.2, AAT can bring down agricultural gross domestic product (GDP) by 5% and 10% (Thirtle et al., 1995; Frisvold and Ingram, 1995). An estimate of the impact of trypanosomiasis on agricultural GDP for 10 African countries that are completely tsetse-infested is presented in Table 1. All over the country, reports of AAT prevalence in livestock vary. Similarly, the methods for detection and identification have not been quite uniform albeit light microscopy has been commonly applied. Other diagnostic method readily employed are card agglutination test (CATT) and the enzyme-linked immunosorbent assay (ELISA); while data from polymerase chain reaction (PCR) has been sparse and recent (Table 2). Over the years, data on the following livestock (cattle, sheep, goat, pigs, camel, donkeys and horses) positive for AAT are thus documented (Table 2). In Nigeria, cattle rearing are occupational jobs. The products and value chain from cattle processing meets different human needs; however, AAT threatens it economic potentials. Trypanosoma vivax and T. Table 1 Estimates of impacts of AAT on agricultural GDP for some African countries infested by tsetse. Sources: World Bank (1999) (estimates of agricultural GDP); Thirtle et al. (1995) and Frisvold and Ingram (1995) (estimates the output elasticity of livestock stock). 1.2. Sterile insect technique (SIT) In the bid to eradicate AAT from Nigeria, tsetse flies have to be eliminated. One method in achieving this is the use of SIT. SIT works on the principle of tsetse - mating behaviour. Unlike male tsetse flies, females mate once in a life time. In using SIT, males are transformed to be sexually sterile by exposure to irradiation and then released into the wild to compete with males for females of same species. Females that mate with sterile males are incapable of producing viable offspring, thereby reducing the tsetse population. Overtime, the few females in the field are then moped-up to achieve tsetse elimination. In 1967, SIT was conceived as a possible tsetse control strategy in Nigeria (Olandunmade et al., 1990). The prospects of SIT raised new hopes for tsetse elimination and consequent eradication of AAT in the country. So in 1987, SIT in combination with other control methods were used to clear G. palpalis from an area of about 1500 km2 in NorthCentral Nigeria (Olandunmade et al., 1990). Ever since, SIT has been halted on account of poor funding which has led to a reinvasion of once cleared areas (Oluwafemi et al., 2008). PATTEC is therefore urged to Country Benin Central African Republic Congo Republic Cote d’Ivoire Gabon Ghana Guinea Guinea-Bissau Sierra Leone Togo Total for 10 countries 325 Agricultural GDP (USD millions in 1997) Impacts of trypanosomiasis with 40% and 80% impacts on total stock of livestock 40% 80% 812 468 65.0 41.2 130.0 82.4 230 2768 380 3178 1039 143 414 512 999.1 18.4 221.4 30.4 254.3 83.2 11.4 33.1 40.9 799.3 36.8 442.8 60.9 508.5 166.3 22.9 66.2 81.9 1598.6 Acta Tropica 176 (2017) 323–331 C. Isaac et al. Table 2 Prevalence of AAT in livestock across the states and zones in Nigeria. Zone Location Number tested Prevalence (%) Method of Investigation Livestock Type Reference North-Central Benue Benue Benue Benue 41.7 8.9 3.8 7.2, 0.5 10.7, 1.3 28 13.1 27.6 1.25 16.8, 25 9.8 53.3 6.3 100 38.0 12.2 4.5 6.4 46.8 1.4 16.6 HCT STM, BCM, HCT STM, BCM CATT, PCR CATT, PCR PCR STM, HCT, BCM STM, HCT, BCM STM, HCT BCM, ELISA STM STM, HCT, BCM STM, HCT HCT STM STM STM PCR STM, BCM PCR Goat, sheep, Cattle and Pigs Cattle Cattle Cattle Pigs Cattle Cattle Sheep, goat Cattle, goat Cattle Cattle Cattle Cattle Cattle Sedentary cattle Cattle and Sheep Slaughtered cattle Cattle Cattle Cattle Pigs Omotainse et al. (2000) Kalu (1995) Enwezor et al. (2012a,b) Karshima et al. (2016c) Benue Benue Benue Kogi Kwara Nasarawa Nasarawa Niger Niger Plateau Plateau Plateau Plateau Plateau Plateau Taraba 163 268 395 600 600 200 214 543 240 310 400 150 300 100 200 740 200 1035 7143 358 712 Ode et al. (2017) Abenga (2015) Kalu et al. (2001) Omoogun and Akinboade (2000) Ijagbone et al. (2004) Oluwafemi et al. (2008) Hassan et al. (2016) Adama et al. (2010) Akinboade et al. (1983) Anosike et al. (2003) Kalejaiye et al. (2004) Pam et al. (2016) Kalu (1996) Majekodunmi et al. (2013) Anene et al. (1991) Karshima et al. (2016b) North-East Adamawa Adamawa and Taraba Bauchi Bauchi Gombe 240 1065 615 448 450 13.3 3.9 6.0 51 4.5 STM, STM, STM, STM, STM, Cattle Cattle from tse tse free regions Goats and sheep Cattle, sheep and goat Cattle, sheep, goat, donkey, pigs Zubairu et al. (2013) Daniel et al. (1993) Daniel et al. (1994) Obaloto et al. (2015) Usman et al. (2008) North-West Kaduna Kaduna Kaduna 526 40 900 9.1 12.5 4.3 STM, BCM HCT, BCM STM, HCT Abenga et al. (2004) Fajinmi et al. (2006) Ezebuiro et al. (2009) Kaduna Kaduna Kaduna Kaduna Kaduna Kaduna Kaduna Kaduna, Bauchi, Plateau Kaduna Kano 1293 634 96 150 150 110 529 243 146 1106 166 152 56 8.4 2.2 15.6 14.7 26.0 40.9 2.1 1.6 37 5.3 1.2 0.7 75.0 STM, STM, STM, STM, STM, STM, STM, BCM PCR HCT, PCR Cattle Cattle Ruminants (Cattle, sheep and goat) Cattle from grazing reserve Cattle Cattle Cattle from abattoir and Farms Cattles from abattoir Sheep Goats, sheep Horses Cattle Cattle Sheep Goats Goats 200 500 31.5 1.8 STM STM, HCT, PCR Camels Cattle Argungu et al. (2015) Fajinmi et al. (2011) Abia Abia Anambra Anambra Anambra and Imo Enugu 1361 125 150 302 264 106 1.9 1.6 30.7 2.98 18.6 14.1 STM STM STM, HCT STM, BCM ELISA STM, BCM Cattle, sheep and goats Goats Pigs Cattle, dogs pigs Cattles Goats Kano, Kaduna, Sokoto, Kebbi Sokoto Sokoto South-East BCM BCM BCM, HCT HCT HCT BCM BCM, HCT HCT PCR PCR HCT, BCM HCT, BCM BCM Enwezor et al. (2009) Samdi et al. (2011) Andrew et al. (2014) Sambo et al. (2017) Muhammad et al. (2016) Wayo et al. (2017) Samdi et al. (2008) Ehizibolo et al. (2012) Takeet et al. (2013) Kalu and Lawwani (1996) Sanni et al. (2013) Enugu 107 13.08 STM, BCT, HCT Sheep, goat Ohaeri (2010) Ukwueze and Kalu (2015) Onah (1991) Enwezor et al. (2012a,b) Ezeani et al. (2008) Anyaegbunam and Okafor (2013) Fakae and Chiejina (1993) South-South Cross river Delta 6203 100 6.53 3.0 STM STM, BCM Cattle Cattle Owai (2011) Enwezor et al. (2012a,b) South-West Ogun Ogun Ogun Ogun Ondo Oyo Oyo Oyo Oyo 200 133 59 265 296 305 189 180 2080 6.0 31.6 71.2 76.6 14.6, 25.0 9.2, 16.4 3.2, 27 3.8 4.1 STM STM PCR PCR BCM, ELISA BCM, ELISA HCT, ELISA STM STM, HCT Akande et al. (2010) Sam-Wobo et al. (2010) Sanni et al. (2013) Takeet et al. (2013) Ijagbone et al. (2004) Ijagbone et al. (2004) Ogunsanmi et al. (2000) Okorafor and Nzeako (2014) Ameen et al. (2008) Oyo 320 4.7 STM, HCT Cattle Cattle Goats Cattle Cattle Cattle Pigs Cattle Ruminants (cattle, goat and sheep) Cattle Fasanmi et al. (2014) HCT = Haematocrit Centrifugation Technique, ELISA = Enzyme-linked immunosorbent assay, STM = Standard parasitological method, BCM = Buffy coat method, PCR = Polymerase Chain Reaction, CATT = Card agglutination test. 326 Acta Tropica 176 (2017) 323–331 C. Isaac et al. for AAT chemotherapy, has been present in Nigeria from decades ago (Kalu, 1995; Anene et al., 2006) to very recently (Sonibare et al., 2016). Resistance is a very serious problem not only because of the few drugs available, but because cross resistance tends to occur between them. For instance, cross resistance between ISM and diminazene has been reported in the field (McDermott et al., 2003; Sinyangwe et al., 2004) in addition to the more established cross resistance to ethidium bromide in ISM resistance (Codjia et al., 1993; Gray and Peregrine, 1993) Resistance to trypanocides is almost always due to gene mutations, in the TbAT1/P2 transporter and the High Affinity Pentamidine Transporter genes for diminazene uptake (Carter et al. 1995; Munday et al. 2013a) and in the γ-subunit gene of the F1F0-ATP synthase for ISM and ethidium bromide uptake (Dean et al., 2013; Eze et al., 2016), both of the T. b. brucei. In T. congolense, resistance to trypanocides is still being characterized, though it is gradually becoming clear that there are differences compared to the T. b. brucei model especially with regards to drug transporters since T. congolense does not have an equivalent of TbAT1/P2 (Munday et al., 2013b). Resistant trypanosomes are selected in African animals in the field by practices such as under-dosing which arise because farmers tend to administer these trypanocides on their livestock by themselves. The decreasing efficacy of trypanocides and the narrow prospects of anti-trypanosome vaccine development in the nearest future have occasioned the search for plants with trypanocidal potentials. Some plants sourced in Nigeria with suggested trypanocidal properties are presented in Table 3. However, further screening of the trypanocidal potentials of these natural products and others should be comprehensively performed on all relevant parameters; and those confirmed should be licensed as prospective candidates to be considered in the development of a new drug. All these therefore would require diligent efforts and huge budgets. We recommend therefore that relevant bodies both locally and internationally should support this initiative in identifying the most suitable botanical(s) capable of overcoming the limitations of the in-use trypanocides. congolense (Savannah and Forest forms) are the common aetiological agents causing nagana in cattle. Studies have recently reported the presence of T. brucei and T. evansi in cattle (Majekodunmi et al., 2013; Takeet et al., 2013). Surveyed areas positive for bovine trypanosomiasis with prevalence data over the years (1993–2017) are respectively presented in Fig. 1 and Table 2. Similarly, T. vivax and T. congolense are mainly responsible for trypanosomiasis infection in sheep and goats with higher infection rate in northern than in the southern region of the country (Table 2). The susceptibility of different breeds of goat have also been reported (Anyaegbunam and Okafor, 2013; Obaloto et al., 2015). A dearth of information exists on the prevalence and effect of porcine trypanosomiasis. Meanwhile, molecular evidence has suggested the presence of T. b. brucei, T. congolense (Forest and Savannah forms) in pigs (Karshima et al., 2016b). Available reports have put porcine trypanosomiasis at 36.8% (Omotainse et al., 2000) and 16.6% (Karshima et al., 2016b) from areas in North-Central and North-East zones respectively. Meanwhile, prevalence of porcine trypanosomiasis in SouthWest, South–South and South-East regions are not available. Horses serve various purposes in Nigeria including sports (polo), pleasure riding, security operations (police and the military) and in traditional ceremonies. Trypanosoma vivax and T. evansi have been isolated from horses in northern Nigeria (Bauchi, Kaduna and Plateau states) with mean prevalence of 1.6% (Ehizibolo et al., 2012). Of the 36 states and Abuja, we could only access AAT data in livestock from 24 states (see Fig. 1, Table 2). With respect to the landmass of Nigeria, survey on livestock population in the different states is largely insufficient. Data analyses on livestock (cattle, sheep and goat) mean prevalence by zone using microscopy (STM, BCM, HCT) estimates the following: North-West (10.8% ± 11.4%), North-Central (17.1% ± 15.7), North-East (17.6% ± 16.8), South-West (9.7% ± 9.0%), South-East (11.9% ± 9.9%) and South–South (4.7 ± 1.8%). Similarly, by PCR, available data estimates North-West (56 ± 19%), North-Central (37.4 ± 9.4%), North-East (17 ± 0%), South-West (73.9 ± 2.7%), South-East (N/A) and South–South (N/A). Furthermore, in AAT-positive livestock, mean prevalence with T. vivax was 48.7%, T. congolense (44.8%), T. brucei (5.8%) and T. evansi (0.7%). Among the sampled livestock (cattle sheep and goats), the overall mean infection rate for cattle (19.4 ± 21.1%) was higher than goat (6.0 ± 10.7) and sheep (12.1 ± 19.3). Considering the limitations of the prevailing method (microscopy) in AAT investigation, results on mean prevalence are likely to be lower than through other means (Nantulya, 1990). Further, a higher prevalence is likely if molecular methods were applied (Takeet et al., 2013). The necessity for a more sensitive and species-specific methods cannot be overlooked as this would present a near-accurate prevalence picture being the first step in developing a potentially successful trypanosomiasis control strategy. The major challenge however in the use of molecular methods for epidemiological studies in Nigeria has been the seldom availability of molecular facilities as they are relatively expensive and largely unaffordable by disease epidemiologists. Data on genomic studies of tsetse in Nigeria would be generally useful for AAT control plan (International Glossina Genome Initiative, 2014). 1.5. Trypanotolerant livestock The availability of trypanotolerant livestock has been recognized as a management strategy for AAT in Africa with an estimated 6% (N’Dama and West African Shorthorn) of the cattle population being trypanotolerant and 17% located in risk areas (Agyemang, 2005). In Nigeria, the cattle population are predominantly Zebu with few Mututru, Keteku, N’dama and Kuri breeds (Resourse Inventory and Management Limited, 1992). Three main breeds of goats are seen, the Sahel/Desert/West African long-legged goat, the Sokoto red and West African dwarf (Ngere et al., 1984); while sheep are Balami, Uda, Yankasa and West African Dwarf (Adu and Ngere, 1979). The great majority of the cattle in Nigeria are owned and managed by pastoralists, which explains the considerable intra- and inter-annual fluctuation in the numbers and distribution across locations. However, there is need to update available information on the distribution of the breeds of livestock in Nigeria. This is imperative in order to evolve a livestock programme that would ensure that areas heavily infested with tsetse, receives trypanotolerant breeds that are likely to interbreed with on-site cattle, while tsetse control activities like trapping and insecticidespraying/insecticide-treated cattle are ongoing. N’dama and West African short horns are known to be trypanotolerant (Murray et al., 1990). Also, Muturu being a crossbreed of Ndama and Zebu has demonstrated resistance to AAT (Takeet et al., 2013). Similarly, having identified trypanotolerant breeds of small ruminants, they should also be introduced into heavily infested-tsetse areas. It is believed that correct assessment and profiling of livestock in the different AAT endemic regions in southern and northern Nigeria would inform on the most appropriate integrated methods that would guarantee a positive and sustainable AAT control effect. Notably, at the stage of engaging integrated methods in AAT control, the cautious adoption of the feature 1.4. Chemotherapy and botanicals One of the mandates of PATTEC-Nigeria is to strategise and execute an effective integrated approach against AAT in the country. This means effective vector control and parasite burden reduction or possibly complete parasite clearance within animal hosts. To achieve the later, chemotherapy is a veritable tool as isometamidium chloride, homidium bromide or chloride and diminazene aceturate are commonly used. However, over the years, the administration of these drugs have been challenged with drug resistance (Mamoudou et al., 2008; Grace et al., 2009), severe side effects (Guttering, 1985), toxicity, inaccessibility, unavailability and its high cost (Legros et al., 2002). Resistance to diminazene and isometamidium, the most important drugs 327 Acta Tropica 176 (2017) 323–331 C. Isaac et al. Table 3 Plants sourced in Nigeria with suggested trypanocidal properties. Plant Scientific name Plant Common/Local Name Plant Part Extraction medium Effective dose/concentration Reference Adenium obesum Acacia nilotica Afrormosia laxiflora Afzelia Africana Anchomanes difformis Desert rose Bagaruwaa Makarfoa African oak Forest anchomanes Stem bark Stem bark Leaves Leaves Rhizome Methanol Methanol Petroleum ether Methanol Methanol 4 mg/ml 400 mg/kg 4 mg/ml 3 mg/ml 2 mg/ml Annona senegalensis Wild custard apple Leaves Water 200 mg/kg Anogeissus leiocarpus African birch Plant bark Aqeous methanol 200 mg/kg Artemisia maritime Boswellia dalzielii Bucholzia coriacea Carissa spinarum Sea wornwood Frankincense tree Musk tree Wild karanda Whole plant Leaves Seed Root chloroform and petroleum ether Methanol Methanol Ethanol Cassytha filiformis Cissus multistriata Cochlospermum planchonii Crateva adansonii Cucurbita pepo Entada abyssinica Khaya senegalensis Lannea kerstingii Lannea welwistchii Lawsonia inermis Magnifera indica Monodora myristica Moringa oleifera Love vine Abeekanna manunb Rawayaa Garlic pear tree Pumpkin Splinter bean African mahogany Farua Ekikac Lallaib Mango African nutmeg Moringa Nauclea latifolia Peristrophe bicalyculata Piliostigma reticulatum Prosopis Africana Tapashiyaa Tubanin dawakia Kalgoa Kiryaa Methanol Aqeous ethanol Water Hexane Water Water Methanol Aqeous methanol Methanol Petroleum ether Water Ethyl acetate Petroleum ether, chlorofoam and methanol Petroleum ether Cold water Water Petroleum ether Saba florida Securidaca longepedunculata Spondias mombim Sterculia setigera Swartzia madagascariensis Syzygium guineense Terminalia avicennioides Terminalia catappa Terminalia superb Tridax procumbens Waltheria indica Ximenia Americana Paste rubber Violet tree Hog plum Kukukia Bayamaa Water pear Baushea Tropical almod Limba Tridax daisy Sleepy morning Wild plum Stem Leaves Stem bark Leaves Seed Stem bark Root Root Leaves Leaves Root Seed Root and stem bark Root Whole plant Leaves Leaves and root bark Root Stem bark Root Root bark Leaves Stem bark Stem bark Stem bark Root and stem Whole plant Whole plant Stem bark 0.4 mg/ml 10 mg/ml 1000 mg/kg > 100 mg/kg of mice body weight 4 mg/ml 400 mg/ml 4 mg/ml 12.5 μg/ml 4 mg/ml 4 mg/ml 3 mg/ml 4 mg/ml 6.3 mg/ml 4 mg/ml 2 mg/ml 12.5 μg/ml 2 and 4 mg/ml Atawodi (2005) Ogbadoyi et al. (2011) Atawodi (2005) Antia et al. (2009) Atawodi (2005), Nwodo et al. (2015) Ogbadoyi et al. (2007), Atawodi (2005) Wurochekke and Anyanwu (2012) Ene et al. (2014) Atawodi et al. (2005) Nweze et al. (2009) Onotu et al. (2013) a b c Aqeous ethanol Water Hexane Petroleum ether Chlorofoam Chlorofoam Water Water Methanol Ethyl acetate Water Water Atawodi (2005) Omale and Joseph (2011) Atawodi (2005) Igoli et al. (2012) Bala et al. (2009) Bala et al. (2009) Antia et al. (2009) Atawodi (2005) Antia et al. (2009) Atawodi (2005) Atawodi (2005) Igoli et al. (2011) Atawodi (2005) 4 mg/ml 50 mg/kg 4 mg/ml 4 mg/ml Atawodi (2005) Abimbola et al. (2013) Atawodi (2005) Atawodi (2005) 400 mg/ml 4 mg/ml 25 μg/ml 4 mg/ml 4 mg/ml 4 mg/ml 2 mg/ml 4 mg/ml 3 mg/ml 200 mg/kg 4 mg/ml 4 mg/ml Omale and Joseph (2011) Atawodi (2005) Igoli et al. (2011) Atawodi (2005) Atawodi (2005) Atawodi (2005) Atawodi (2005) Bala et al. (2009) Antia et al. (2009) Abubakar et al. (2012) Bala et al. (2009) Bala et al. (2009) Name in Hausa. Name in Ganye. Name in Yoruba. Nigeria is domiciled, there has been no significant financial backing to PATTEC-Nigeria from the government or other sources since Nigeria joined the African Union-PATTEC initiative. The second requirement relates to self-assessment and planning. Here a work-plan must be developed after taking into consideration existing capacities, epidemiological knowledge and institutional arrangement across the country. PATTEC-Nigeria is yet to come up with a comprehensive and a dependable work-plan because in our view it has not sufficiently appraised what is presently on ground. The survey-data presented in this report are largely from researchers across the country collected at various times; and they are unstructured as well as scanty. The only and most comprehensive tsetse-survey effort in Nigeria was embarked upon by PATTEC-Nigeria in Jigawa state (North-East) covering all the local government areas within the state. An organised/structured and comprehensive tsetse and AAT survey in every local government area of a state across the six geopolitical zones should be an inevitable first step towards AAT control. Thereafter, PATTEC-Nigeria has to harmonise and geo-reference epidemiological and entomological data as this is one of stage-two under the PCP model should instruct the application of cost-effective vector control (Torr et al., 2007; Bouyer et al., 2009; Van den Bossche, 2010; Bauer et al., 2011) with the responsible use of trypanocides to limit the emergence and spread of drug resistance (Giordani et al., 2016). 2. Conclusion Data available in this report has clearly indicated a dearth of preliminary information on tsetse distribution and AAT prevalence across the states particularly in southern Nigeria. Also, in most locations where AAT data are available, they are substantially not reliable owing to the relatively less specific and sensitive tools used for diagnosis. Unambiguously, Nigeria is below the stage-one of the PCP because the requirement to enter PCP stage-one would involve strong political and heavy financial commitments to a specialized and a national structure dedicated to tsetse and AAT control. Although there is an institution (Nigerian Institute for Trypanosomiasis Research) in which PATTEC328 Acta Tropica 176 (2017) 323–331 C. Isaac et al. brucei isolated from a dog is cross-resistant to pentamidine in experimentally infected albino rats. Parasitology 132, 127–133. Anosike, J.C., Opara, M.N., Okoli, C.G., Kyakya, A., Okoli, I.C., 2003. Bovine trypanosomiasis in sedentary cattle at previously assumed trypanosome-free Jos plateau, Nigeria. Niger. Vet. J. 24, 33–36. Antia, R.E., Olayemi, J.O., Aina, O.O., Ajaiyeoba, E.O., 2009. In vitro and in vivo animal model antitrypanosomal evaluation of ten medicinal plant extracts from south west Nigeria. Afr. J. Biotechnol. 8, 1437–1440. Anyaegbunam, L.C., Okafor, O.J., 2013. 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