Echinococcus granulosus sensu lato in animal intermediate hosts: What is with the organ location?

Organ or tissue tropism/preference in many parasites is essential for their establishment, survival and pathogenesis. In protozoan parasites e.g. Trypanosoma and Plasmodium, tissue tropism is associated with many important aspects such as transmission, treatment, and pathogenesis. In these parasites, tissue tropism is achieved by mechanisms such as sequestration, extravasation, transcellular migration, and vascular permeability. In contrast, little is known about the mechanism behind organ tropism/preference and the potential implication in parasitic metazoans like Echinococcus. Since intraspecies/genetic variation was described for Echinococcus, the organ preference of currently known species and subspecies among animal intermediate hosts remains unclear or perhaps poorly investigated. Here, analysis of 89,359 Echinococcus cysts from different animal intermediate hosts across 47 countries suggests a potential organ distribution pattern in different animal intermediate hosts. For example, E. granulosus s.s. (G1, G3) and E. canadensis (G7) were found more in the liver of sheep and pigs, respectively than in other organs, whereas E. ortleppi and E. canadensis G6 were significantly higher in the lung of cattle and camels, respectively. While the mechanism of organ tropism in Echinococcus and whether it is species/genotype-dependent, host-dependent, or a combination of both is still a subject of future investigations, further and detailed investigation could provide significant information that may be applicable in the diagnosis and treatment of organ-specific cystic echinococcosis or designing host or genotype-specific interventions.

A meta-analysis of Cryptosporidium species in humans from southern Africa (2000-2020).

Abstract: The epidemiology of cryptosporidiosis in southern Africa is largely unknown. The disease is associated with diarrhea and nutritional deficiencies, leading to severe morbidity and mortality among immune-compromised patients. This study aimed to assess the pooled prevalence of Cryptosporidium spp. infection among immune-compromised humans in southern Africa over the past 20 years. Reports of Cryptosporidium spp. infection in humans published between 2000 and 2020 using Google Scholar, PubMed, Ovid Medline, African Journal Online (AJOL), and Web of Science literature databases were obtained. Inclusion criteria of sorted articles for Cryptosporidium spp. infection were standardized using preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist. A total of 22 eligible studies were sorted for meta-analysis. Overall prevalence of Cryptosporidium spp. infection in southern African countries with reports was 16.8% (95% CI 9.7-25.3). Sub-group analysis showed a pooled prevalence of 25.2, 20.5, and 17.9% among HIV/AIDS patients, children, and diarrhoeic individuals, respectively. Pooled prevalence was highest in South Africa and lowest in Zimbabwe across examined individuals. The pooled prevalence of Cryptosporidium spp. infections in diarrhoeic patients was highest in individuals from Botswana (17.6%) which is significantly different (Χ 2 = 9.337; P = 0.002) from South Africans (12.7%). South African individuals with HIV/AIDS showed the highest pooled prevalence of Cryptosporidium infections than other countries. The high prevalence of Cryptosporidium spp. infections among immune-compromised patients in southern Africa showed that the pathogen is of significant importance in this region. Continuous studies on the genetic characterization of Cryptosporidium spp. isolates and associated risk factors are needed across southern Africa to identify the predominant subtypes in humans. Supplementary Information: The online version contains supplementary material available at 10.1007/s12639-021-01436-4.

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.].

Economic impact assessment of small ruminant fasciolosis in Nigeria using pooled prevalence obtained from literature and field epidemiological data.

Small ruminant fasciolosis (SRF) is a snail - borne disease, transmitted by tropical freshwater snail, Lymnaea (Radix) natalensis in Nigeria. Fasciolosis in small ruminants is often neglected and information on the prevalence and economic losses are scarce. The aim of this study was to evaluate the prevalence of SRF and provide estimated annual economic losses associated with the disease. Meta-analysis revealed pooled prevalence of 2.1% (95%CI: 0.0-5.8) in studies across Nigeria, while the distribution of L. natalensis was 13.2% (95%CI: 11.6-14.1) among collected snails. Approximately 29.4% livestock owners disagree with veterinary inspectors on the liver condemnation of their slaughtered animals in the abattoir during meat inspection. No significant difference (P > 0.05) was observed between SRF in sheep and goats. Mortality cost was estimated at US$ 55,671,620, while total liver condemnation was US$ 552,448. Direct losses were estimated at US$ 60,132,318 and indirect losses at US$ 17,807,706. The overall economic losses attributable to SRF in Nigeria was estimated at US$ 77,940,024 / annum (equivalent to 28.06 billion naira). Fasciolosis in small ruminant remains a major concern for Nigerian livestock industry. The present and future impact of the disease was further discussed. Considering the high economic burden of fasciolosis in small ruminants, improved disease surveillance and meat inspection, regular treatment and control campaigns are important to reduce infection rates and economic losses.

Financial losses estimation of African animal trypanosomosis in Nigeria: field reality-based model.

INTRODUCTION: Theoretical and modelling approaches were undertaken on Nigerian livestock industry to estimate financial losses due to African animal trypanosomosis. METHODS: Surveys were conducted between March 2018 and February 2019 to include focus group interactions, in-depth household engagements concerning livestock practices in relation to AAT. Financial losses estimation on livestock were targeted to provide ways to regain cost and maximize household livelihoods. Mathematical equation was developed to project the effects of intervention strategies. Important variables such as mean AAT prevalence, incidence rate, birth rate, morbidity and mortality were estimated and inserted in the model. RESULTS: Mean total income per capita was US$ 1.31 / person / day among livestock producers in Nigeria. A total of US$ 518. 9 million were estimated from direct losses, while US$ 58.8 million as indirect losses. Annual estimated losses to AAT from cattle, sheep, goat and pigs in Nigeria is US$ 577.7 million. This is equivalent to 207.98 billion Nigerian naira and represents 6.93% of annual livestock GDP in the country. This could increase to 85% in the next 50 years if there are no proper control interventions. Control efforts could reduce the losses to US$ 16.7 million at the rate of 0.2% during the same period. DISCUSSIONS: AAT has severe socioeconomic impact on producer's livelihood and urgent improved control intervention strategies should be instituted to reduce the losses attributed to the disease.

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.

Economic model of bovine fasciolosis in Nigeria: an update.

Bovine fasciolosis is a zoonotic infection transmitted by infected freshwater snail-Lymnaea (Radix) natalensis-in tropical regions. The prevalence of bovine fasciolosis in Nigeria is overwhelming with huge financial cost. In the chronic form of the disease, hyperplastic cholangitis and calcification of bile ducts occur with severe liver damage. The aim of the study was to estimate annual economic losses of bovine fasciolosis in Nigeria. Disease prevalence was estimated at 18.3% (8.5-30.6), average annual disease incidence is maintained at 2.5%, an estimated mortality rate of 1.5%, a total liver condemnation rate of 11.1% were estimated from affected liver due to fasciolosis, annual slaughter rate of 10.5% and a total cattle population of 20 million. A total of 7.3% livestock owners consider fasciolosis as a threat, while only 4.3% have ever used molluscicide. Treatment cost of controlling fasciolosis is estimated at US$375,000, which puts the total annual loss due to fasciolosis at US$26.02 million. Both direct and indirect sources of production losses have an impact on the livestock industry in Nigeria. Bovine fasciolosis threatens food security in Nigeria; therefore, further awareness among livestock owners is needed on control strategies to improve the income base for small-scale livestock farmers.

Risk factors associated with seropositivity for Toxoplasma gondii in population-based studies among immunocompromised patients (pregnant women, HIV patients and children) in West African countries, Cameroon and Gabon: a meta-analysis.

Toxoplasmosis in immunocompromised individuals can be life threatening. The information needed for proper control and management strategies in endemic West African countries is lacking, hence a systematic review and meta-analysis were performed. This study aimed to determine the seroprevalence of anti-Toxoplasma gondii among pregnant women, HIV/AIDs and children in West Africa, Cameroon and Gabon. The epidemiology of the disease published between 1984 and 2019 using PubMed, Web of Science, Ovid MEDLINE, AJOL and Google Scholar databases were identified. Studies that met the inclusion criteria of Toxoplasma gondii infections under the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist were analysed. A total of 58 eligible studies were selected for meta-analysis. These studies considered 18,674 hosts and an overall pooled seroprevalence of anti-T. gondii antibodies were 45.4, 39.0 and 29.5% for pregnant women, HIV/AIDS patients and children, respectively. Pooled seroprevalence was highest in Gabon and lowest in Mali for pregnant women while highest levels of seropositivity for anti-T. gondii antibodies for HIV/AIDS individuals and children were both observed in Ghana. The major risk factors associated with anti-T. gondii seropositivity were gravida status, contact with cats, consumption of raw vegetables and /fruits, age and CD4 counts. More studies are needed to determine seroconversion rate. Improved sensitization among immunocompromised patients on T. gondii and its risk factors will be an efficient method to reducing the prevalence of the disease. One Health interventions involving transdisciplinary, integrative research and capacity building are necessary to address the problem of toxoplasmosis in West Africa.

Epidemiological dynamics and associated risk factors of S. haematobium in humans and its snail vectors in Nigeria: a meta-analysis (1983-2018).

Schistosoma haematobium, a major pathogen of urogenital schistosomiasis, has been reported to be affecting an estimated 30 million people in Nigeria. Current national estimates of S. haematobium and its cercariae, in humans and snail vectors respectively, are lacking in Nigeria, hence systematic meta-analyses were conducted to understand the disease dynamics in the endemic country over a period of 35 years based on publications from five databases (AJOL, Ovid MEDLINE, Google Scholar, PubMed and Web of Science). The preferred reporting items for systematic reviews and meta-analyses (PRIMSA) checklist were used as the standard guide for the analyses. The prevalence of S. haematobium in human hosts in Nigeria using quality effects model was 32.1% (27.3-37.2), while schistosome cercariae were observed at 3.5% (0.0-11.9), 18.2% (4.7-36.8) and 18.7% (0.0-46.1) and for B. forskalii, Bulinus globosus and B. truncatus, respectively. The high report of schistosome cercariae indicates the continuous transmission of S. haematobium in humans especially with individuals who have frequent contact with freshwater. Heterogeneity of subgroup analyses (regions, zones, sex, age groups, diagnostic techniques) and risk factors (pathological signs, occupation, water sources, anthropogenic activities, treatment) were determined. The result showed prevalence of an endemic moderate class infection that has been linked to several risk factors. Therefore, there is need for increased awareness on the prevalence, transmission routes and treatment strategies to mitigate the disease in this endemic area.

A meta-analysis of Toxoplasma gondii seroprevalence, genotypes and risk factors among food animals in West African countries from public health perspectives.

Toxoplasma gondii has been incriminated as an important opportunistic zoonotic protozoan parasite in food animals. A West African meta-analysis was conducted to assess the seroprevalence, genotypes and risk factors of T. gondii infection in food animals. Databases were searched electronically, considering T. gondii infection in cattle, goats, sheep, pigs and chickens. These were conducted to estimate overall pooled seroprevalence, confidence intervals at 95 % (CI) and heterogeneity using quality effects model. Qualitative data on risk factors to determine effects on human populace and possible control strategies were evaluated. Pooled seroprevalence of anti-T. gondii antibodies for food animals was 25.5 % (18.9-32.8); and for each animal namely cattle, sheep, goats, pigs and chickens were 16.3, 29.1, 18.1, 35.9 and 36.0 %, respectively. Most studied food animals were observed in Nigeria, while the highest seroprevalence was observed in examined goats from Republic of Benin, the lowest was in cattle from the same country. Substantial variability (Q = 2759.5; I2 = 98.3; Qi = 17.3; df = 48) among studies and lack of publication bias (LFK index = -0.08) in overall assessment was observed. In spite of the high seroprevalence in food animals, awareness and research activities in most endemic West African countries is low. Failure to associate the common risk factors have limited the reliable estimation of T. gondii infection. Therefore, more efforts are needed in awareness campaign, management practises, careful treatment of contaminated environment with cat faeces, among other measures to assist in the prevention of T. gondii in food animals.

Epidemiology of Cryptosporidium infection in different hosts in Nigeria: A meta-analysis.

Cryptosporidium is a medical and veterinary significant protozoan parasite that infects all classes of vertebrates. Environmental contamination with infective oocyst increases the risk of transmission to susceptible host. Estimates of Cryptosporidium prevalence in humans and animals are lacking in Nigeria, therefore a systematic review and meta-analysis were performed to understand the epidemiology of the disease over a period of 30 years using publications from EMBASE, Ovid MEDLINE, Web of Science, AJOL and Google Scholar databases. Studies that met the inclusion criteria of Cryptosporidium infections under the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist were analysed. Point estimates prevalence and subgroup analyses based on potential risk factors and diagnostic techniques were evaluated at 95% confidence interval (CI). A total of 64 eligible studies published between 1987 and 2017 were selected for meta-analysis. The prevalence of Cryptosporidium infection using quality effects model among human, cattle, sheep, goat, pigs, laboratory animals and birds was estimated as 15.0, 26.1, 16.6, 26.0, 20.1, 9.0 and 7.2%, respectively. The high report of C. parvum subtype family IIc indicates the importance of anthroponotic transmission of Cryptosporidium in Nigeria. Heterogeneity of subgroup (regions, species) and risk factors (HIV status, age, gender, faecal type) analyses were determined. The pooled prevalence of Cryptosporidium spp. in different hosts were high and linked with several risk factors such as environmental contamination and animal contact. There is need for increased awareness on the prevalence of the disease to provide strategies that mitigate the disease in humans and animals.

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.

Comparative insecticidal activity of cypermethrin and cypermethrin-mix applications against stomoxyine vectors.

Stomoxyines are mechanical vectors of several pathogens of livestock with severe consequences such as low productivity from constant irritation and disturbance. In vitro and in vivo bioassays were conducted to confirm the efficacy of cypermethrin analogues on stomoxyines. Cattle treated with cypermethrin (Pantex 30 g l-1) and cypermethrin-mix (cypermethrin + oil from Senna occidentalis locally prepared by Fulani herdsmen) were compared using the restricted insecticidal application (RAP) method and a local Fulani application approach (FAA), while untreated cattle serve as control. A total of 550 speciated-fed Stomoxys niger were exposed to graded concentration of cypermethrin (Group A-D) at 30 µg/ml, 20 µg/ml, 10 µg/ml, 5 µg/ml, 1 µg/ml and 0.5 µg/ml. After 48 h, the flies were assessed for mortality. In vivo bioassay of behavioural responses to stomoxyines showed greater mean percentage repellence using RAP (94.6%) of cypermethrin when compared with FAA (46.3%). The sigmoidal non-linear regression model curve of in vitro bioassay showed cypermethrin (Pantex®-group A) to be most effective with LC50 of 1.52 µg/mL and it is significantly more effective than cypermethrin (Ectopouron®-group B) and cypermethrin-mix (Fulani cypermethrin mixture-group C) at 22.62 µg/ml and 20.62 µg/ml concentration, respectively. In this study, Pantex® demonstrated excellent stomoxyine repellence using RAP method with significant insecticidal effect. Therefore, the appropriate use of cypermethrin insecticides using RAP method is recommended for vector control to prevent African animal trypanosomiasis in Nigeria.

Alighting and Feeding Behavior of Trypanosome-Transmitting Vectors on Cattle in Nigeria.

Vector control is important to effectively prevent trypanosomiasis. Therefore, alighting and feeding responses of trypanosome-transmitting vectors were conducted in Nigeria. The aim of this study was to assess the landing preference, level of fly annoyance on cattle, and feeding behavior by direct observation of cows, bulls, and calves. The percentage of Glossina species, Tabanus species, and stomoxyine that fed on cattle blood after landing varied according to the age and sex of the cattle host. Although most flies left the cattle host before completing their meal because of host defensive behaviors, an average of 78, 19.6, and 10.2% of Glossina, Tabanus, and stomoxyines, respectively, were fully engorged. The longest mean feeding time was observed in Glossina. Over more than 90% of Glossina spp. landed on the belly and legs. Most Tabanus spp. (85%) also landed on the belly and legs while Tabanus par Walker (Diptera: Tabanidae) often landed on the back (45%). Half of Stomoxys species landed on the head and neck. Vector flies' feeding success varied according to cattle host age and was negatively correlated with defensive host behaviors and apparent fly density. Hence, fly defensive behaviors contribute to trypanosomiasis dynamics in a cattle herd, and expended energy from defensive behaviors could adversely affect productivity.

A review of wildlife tourism and meta-analysis of parasitism in Africa's national parks and game reserves.

The recent increase of parasitic diseases associated with wildlife tourism can be traced to human contact with wildlife and intense modification of wildlife habitat. The continental estimates of parasitic diseases among visited wildlife-tourists and mammalian wildlife present in conservation areas are lacking; therefore, a general review was necessary to provide insights into Africa's parasitic disease burden and transmission between humans and wildlife. A two-step analysis was conducted with searches in Ovid MEDLINE, EMBASE, PubMed, Web of Science and Global Health. All diseases reported without prevalence were grouped and analysed as categorical data while meta-analysis of prevalence rates of parasitic diseases in wildlife from national parks and reserves in Africa was conducted. Only 4.7% of the tourist centres reported routine wildlife diagnosis for parasitic diseases. Disease intensity shows that cryptosporidiosis and seven other parasitic diseases were observed in both human and wildlife; however, no significant difference in intensity between human and wildlife hosts was observed. Schistosomiasis intensity reports showed a significant increase (P < 0.05) while entamoebiasis showed a significant decrease (P < 0.05) in humans as compared to wildlife. Visiting tourists were more infected with malaria, while wildlife was more infected with parasitic gastroenteritis (PGE). The meta-analysis of wildlife revealed the highest prevalence of PGE with mixed parasites and lowest prevalence of Giardia spp. at 99.9 and 5.7%, respectively. The zoonotic and socioeconomic impact of some of these parasites could pose a severe public threat to tourism. Pre- and post-travel clinical examinations are important for tourists while routine examination, treatment and rational surveillance are important for these animals to improve wildlife tourism.

A meta-analysis of the prevalence of African animal trypanosomiasis in Nigeria from 1960 to 2017.

BACKGROUND: African animal trypanosomiasis is an economically significant disease that affects the livestock industry in Nigeria. It is caused by several parasites of the genus Trypanosoma. National estimates of the disease prevalence in livestock and tsetse flies are lacking, therefore a systematic review and meta-analysis were performed to understand the trend of the disease prevalence over the years. METHODS: Publications were screened in Web of Science, Ovid MEDLINE, Global Health, EMBASE and PubMed databases. Using four-stage (identification, screening, eligibility and inclusion) process in the PRIMSA checklist, only studies that met the inclusion criteria for AAT and tsetse infections were analysed. Point estimates prevalence and subgroup analyses based on diagnostic techniques in livestock were evaluated at 95% confidence interval (CI). RESULTS: A total of 74 eligible studies published between 1960 and 2017 were selected for meta-analysis. This covers the six geopolitical zones, involving a total of 53,924 animals. The overall prevalence of AAT was 16.1% (95% CI: 12.3-20.3%). Based on diagnostic techniques, the prevalence of AAT in cattle was highest in PCR followed by serology and microscopy while the highest prevalence in pigs was observed with serology. Out of 12,552 tsetse flies examined from 14 eligible studies, an overall prevalence of 17.3% (95% CI: 4.5-36.0%) and subgroup prevalence of 49.7% (95% CI: 30.7-68.8%), 11.5% (95% CI: 6.1-18.5) and 4.5% (95% CI: 1.8-8.8%) in G. morsitans, G. tachinoides and G. palpalis, respectively, were observed using the random effects-model. CONCLUSIONS: The prevalence of trypanosomes in both vectors and animal hosts was high in Nigeria. Therefore, further research on risk factors, seasonal and transhumance effects, vectoral capacity and competence are warranted for an effective control of AAT in Nigeria.