Gap Analysis of the Habitat Interface of Ticks and Wildlife in Mexico

Mexico is a highly diverse country where ticks and tick-borne diseases (TBD) directly impact the health of humans and domestic and wild animals. Ticks of the genera Rhipicephalus spp., Amblyomma spp., and Ixodes spp. represent the most important species in terms of host parasitism and geographical distribution in the country, although information on other genera is either limited or null. In addition, information regarding the influence of global warming on the increase in tick populations is scarce or nonexistent, despite climate conditions being the most important factors that determine tick distribution. In order to aid in the management of ticks and the risks of TBD in humans and domestic animals in Mexico, an analysis was conducted of the gaps in information on ticks with the purpose of updating the available knowledge of these ectoparasites and adapting the existing diagnostic tools for potential distribution analysis of TBD in wildlife. These tools will help to determine the epidemiological role of wildlife in the human–domestic animal interface in anthropized environments in Mexico.

Predictive Analytics of Cattle Host and Environmental and Micro-Climate Factors for Tick Distribution and Abundance at the Livestock–Wildlife Interface in the Lower Okavango Delta of Botswana

Tick distribution and abundance is influenced by several factors that include micro-climate and environmental and host factors. Contextual understanding of the role played by these factors is critical to guide control measures. The aim of this study was to determine the predictive value of these factors for changes in tick distribution and abundance at the livestock–wildlife interface of the lower Okavango Delta. A two-stage quota sampling design was adopted to select 30 clusters of seven cattle each for tick investigation. Tick investigation was done by lifting the tail to count the total number of ticks at the anno-vulva region during the four meteorological seasons of the year. Additional data were collected on ear tag number, location of origin, sex, age, body condition score (BCS), season of the year, stocking density, and Normalized Difference Vegetation Index values of source terrain. A random effects model was used to evaluate predictive value of the above for tick abundance. Additional mapping of tick distribution pattern in the abattoir catchment area was conducted using spatial autocorrelation and hot-spot analysis. Tick intensity of infection increased linearly from males to females (Z = 3.84, p < 0.001), decreased linearly from lower to higher BCS (Z = −4.11, p < 0.001), and increased linearly from cold-dry through dry to wet seasons (Z = 10.19, p < 0.001). Significant clustering of neighboring crushes on account of tick count was noted in the late-hot-dry season, with high tick count in crushes located along the seasonal flood plains and low tick counts in those located in the dry grasslands. It was concluded from this study that cattle tick abundance is influenced largely by season of the year and that the micro-climatic conditions brought about by the seasonal flooding of the delta have a decided effect on tick distribution during the driest of the seasons. Our study has, for the first time, profiled drivers of tick distribution and population growth in this unique ecosystem. This has the potential to benefit human and veterinary public health in the area through implementation of sustainable tick control strategies that are not heavily reliant on acaricides.

Ticks of the genus Rhipicephalus Koch, 1844 in Senegal: Review host associations, chorology, and associated human and animal pathogens

Ticks of the genus Rhipicephalus (Acari: Ixodidae) in Senegal were reviewed. The data presented originate from a tick collection maintained at IRD’s Laboratory of Medical Entomology since 1967 and continuously enriched with samples obtained from different vertebrate hosts captured during various projects conducted in Senegal from 1987 to 2007. Fifteen Rhipicephalus tick species were collected and characterized, resulting in 1127 referenced collections. Three species were of the Boophilus subgenus: Rhipicephalus (Bo.) annulatus, Rh. (Bo.) decoloratus and Rh. (Bo.) geigyi. The twelve others were Rh. boueti, Rh. cuspidatus, Rh. evertsi, Rh. guilhoni, Rh. lunulatus, Rh. muhsamae, Rh. sanguineus, Rh. senegalensis, Rh. sulcatus, Rh. tricuspis, Rh. turanicus and Rh. ziemanni. Although there were recent indications that Rh. turanicus should have been considered as part of the Rh. sanguineus s.l. complex, data regarding these two ticks were presented separately. The collection comprised 14,165 tick specimens at different developmental stages. Data concerning their host relationships as well as distribution and seasonal dynamics were also presented. Vertebrate hosts were identified and listed in the different ecological zones of Senegal. The role of the ticks as potential vectors of pathogens has been reviewed. Climate change, causing variations in rainfall and temperature, will impact tick distribution and dynamics. The situation supports the necessity of this inventory of tick populations for (re)emerging tick-borne diseases surveillance and monitoring.

Survey of cattle tick infestation on farm herds in Ogun state, Nigeria

Cattle in the tropics are exposed to varying levels of challenges r from endo and ectoparasites as well as environmental stressors. Ticks have been recognized as the most notorious threat to cattle because of their hide damaging and disease vector. As a result of these, continuous study of tick distribution on cattle is necessary. Two hundred and five cattle of determined breed, sex and age, were randomly sampled from eight different locations across four local Government areas of Ogun state in 2015. Harvested ticks were identified to species level. Variation in tick distribution across age, sex and locations were subjected to statistical analysis. Among the 205 cattle sampled, 125 (61%) had ticks while 80 (39%) had no ticks, 84 (67%) female have ticks, 27 (33%) do not have, 41 (44%) males have ticks and 53 (56%) do not have. The mean age of the cattle sampled was 3.0±0.1 years, with a mean Packed Cell Volume (PCV) of 30.8±0.4%. Amblyommavariegatum was the most prevalent tick (76%), followed by Rhipicephalus (Boophilus) decoloratus (20%), Rhipicephalus (Boophilus) microplus (2%) while Rhipicephalus (Boophilus) annulatus. and Hyalommam arginatum were 1% respectively. Age and sex of cattle were discovered to be statistically significant in this study. Considering the economic importance of ticks in regards to morbidity and mortality; appropriate tick control strategy and technique need to be applied and constant tick surveillance should be encouraged in the study area

Identification of Bio-climatic Determinants and Potential Risk Areas for Kyasanur Forest Disease in Southern India using MaxEnt Modelling Approach

Background: Kyasanur Forest Disease (KFD), known as monkey fever was for the first time reported in 1957 from Shivamogga district of Karnataka. But since 2011, it is spreading to the neighbouring state of Kerala, Goa, Maharashtra, and Tamil Nadu. The disease is transmitted to humans, monkeys and by the infected bite of ticks Haemaphysalis spinigera. It is known that deforestation and ecological changes are the main reasons for KFD emergence, but the bio-climatic understanding and emerging pathways remain unknown.Methods: The present study aims to understand the bio-climatic determinants of KFD tick distribution in southern India using Maximum Entropy (MaxEnt) model. The analysis was done using 34 locations of Haemaphysalis spinigera occurrence and nineteen bio-climatic variables from WorldClim. Climatic variables’ contribution was assessed using the jackknife test and mean AUC 0.859 which indicated the model performs with very high accuracy.Results: Most influential variables affecting the spatial distribution of Haemaphysalis spinigera were the average temperature of the warmest quarter (bio10, contributed 32.5%), average diurnal temperature range (bio2, contributed 21%), precipitation of wettest period (bio13, contributed 17.6%), and annual precipitation (bio12, contributed 11.1%). The highest probability of Haemaphysalis spinigera presence was found when mean warmest quarter temperature ranged between 25.4-30°C. The risk of availability of the tick increases noticeably when the mean diurnal temperature ranged between 8-10°C. The tick also preferred habitat having an annual mean temperature (bio1) between 23-26.2°C, mean temperature of the driest quarter (bio9) between 20-28°C, and mean temperature of the wettest quarter (bio8) between 22.5-25°C.Conclusions: The results have established the relationship between bioclimatic variables and KFD tick distribution and mapped the potential areas for KFD in adjacent areas wherein surveillance for the disease is warranted for early preparedness before the occurrence of outbreaks etc. The modelling approach has been found a very useful tool to link bioclimatic variables with present and predicted distribution of Haemaphysalis spinigera tick .

Modeling the potential climate change- induced impacts on future genus Rhipicephalus (Acari: Ixodidae) tick distribution in semi-arid areas of Raya Azebo district, Northern Ethiopia

Background Climate change is believed to be continuously affecting ticks by influencing their habitat suitability. However, we attempted to model the climate change-induced impacts on future genus Rhipicephalus distribution considering the major environmental factors that would influence the tick. Therefore, 50 tick occuance points were taken to model the potential distribution using maximum entropy (MaxEnt) software and 19 climatic variables, taking into account the ability for future climatic change under representative concentration pathways (RCPs) 4.5 and 8.5, were used. Results MaxEnt model performance was tested and found with the AUC value of 0.99 which indicates excellent goodness-of-fit and predictive accuracy. Current models predict increased temperatures, both in the mid and end terms together with possible changes of other climatic factors like precipitation which may lead to higher tick-borne disease risks associated with expansion of the range of the targeted tick distribution. Distribution maps were constructed for the current, 2050, and 2070 for the two greenhouse gas scenarios and the most dramatic scenario; RCP 8.5 produced the highest increase probable distribution range. Conclusions The future potential distribution of the genus Rhipicephalus show potential expansion to the new areas due to the future climatic suitability increase. These results indicate that the genus population of the targeted tick could emerge in areas in which they are currently lacking; increased incidence of tick-borne diseases poses further risk which can affect cattle production and productivity, thereby affecting the livelihood of smallholding farmers. Therefore, it is recommended to implement climate change adaptation practices to minimize the impacts.

Counting Ticks (Acari: Ixodida) on Hosts Is Complex: A Review and Comparison of Methods

Locating and counting parasites on a host is a fundamental aspect of ecological research and basic veterinary and clinical practice. Variability in the biology and behavior of both hosts and parasites creates many methodological, logistical, and ethical considerations that must be made to collect this deceptively simple measurement. We identified methods that are used to count ticks (Acari: Ixodida, Leach 1815) on hosts by reviewing the methods sections of relevant published studies. Unfortunately, there is no best method agreed upon by scientists to collect ticks from hosts. In general, we suggest that studies focusing purely on counting ticks on hosts should use more sensitive methods to determine patterns of tick distribution on the surfaces of unconscious or deceased hosts in order to provide host body regions to target in future studies to maximize tick detection ability and limit the costs of research for researchers and the host animals involved. As ticks are counted on hosts for many different reasons, researchers must be goal oriented and chose methods that are appropriate for addressing their specific aims.