Risk Factors and Spatio-Temporal Patterns of Human Rabies Exposure in Northwestern Tigray, Ethiopia

Gebru G, et al. Risk Factors and Spatio-Temporal Patterns of Human Rabies Exposure in Northwestern Tigray, Ethiopia. Annals of Global Health. 2019; 85(1): 119, 1–12. DOI: https://doi.org/10.5334/aogh.2518 ORIGINAL RESEARCH Risk Factors and Spatio-Temporal Patterns of Human Rabies Exposure in Northwestern Tigray, Ethiopia Gebreyohans Gebru*, Gebremedhin Romha†, Abrha Asefa‡, Haftom Hadush§ and Muluberhan Biedemariam‖ Background: Rabies is a neglected tropical disease, which is economically important with great public health concerns in developing countries including Ethiopia. Epidemiological information can play an important role in the control and prevention of rabies, though little is known about the status of the disease in many settings of Ethiopia. The present study aimed to investigate the risk factors and spatio-temporal patterns of human rabies exposure in Northwestern Tigray, Ethiopia. Methods: A prospective study was conducted from 01 January 2016 to 31 December 2016 (lapsed for one year) at Suhul general hospital, Northern Ethiopia. Data of human rabies exposure cases were collected using a pretested questionnaire that was prepared for individuals dog bite victims. Moreover, GPS coordinate of each exposure site was collected for spatio-temporal analysis using hand-held Garmin 64 GPS apparatus. Later, cluster of human rabies exposures were identified using Getis-Ord *Gi statistics. Results: In total, 368 human rabies exposure cases were collected during the study year. Age group of 5 to 14 years old were highly exposed (43.2%; 95% CI, 38.2–48.3). Greater number of human rabies exposures was registered in males (63%; 95% CI, 58.0–67.8) than females (37%; 95% CI, 32.1–42.0). Residents of rural (85.6%; 95% CI, 81.6–88.8) areas were at greater risk to rabies than urban residents (14.4%; 95% CI, 11.2–18.4). Higher proportion of human rabies exposures were caused by unprovoked (96.5%; 95% CI, 94.0–98.0) and unvaccinated (85.9%; 95% CI, 81.9–89.1) dogs. All rabies exposures were exclusively caused by dog bites and the majority of them (80.4%; 95% CI, 76.0–84.2) were caused by stray dogs. Results of spatio-temporal analysis showed that Asgede Tsimbla, Endaselassie and Laelay Adiyabo districts experienced the highest burden of rabies exposure; identified as hot spots. Strong peaks of human rabies exposure occurred between March and July months. Conclusion: The present study provided basic epidemiological information on the potential risk factors associated with human rabies exposure. Moreover, our findings provided basis for understanding the spatio-temporal patterns of human rabies in Northwestern Tigray districts for the first time. Background available for humans and dogs [10, 11]. Although most Rabies is a fatal viral disease that affects the central developed countries have eliminated the disease, rabies nervous system of all warm-blooded animals, including is yet the most important deadly disease in developing humans [1–3]. Domestic dogs have remained as the most countries with low public health and veterinary service important vectors worldwide, causing greater than 95% settings [12]. of all human rabies cases [4–8]. Rabies is almost 100% Rabies is estimated to cause 59,000 human deaths per fatal once the symptoms of the disease develop [2, 9, 10]. year globally. It also causes about 3.7 million disability- However, effective vaccines to prevent rabies are widely adjusted life years (DALYs) burden and 8.6 billion USD economic losses per year in the world [12]. Elimination * Department of Animal Sciences, College of Agriculture, Aksum of dog-transmitted rabies as a public health problem has University, Shire Campus, Shire, Tigray, ET been documented to be feasible by vaccinating dogs and † Department of Animal Production and Technology, College providing post-exposure prophylaxis (PEP) to humans of Agriculture and Environmental Science, Adigrat University, until dog rabies is eliminated [3, 13, 14]. However, this Adigrat, Tigray, ET should be complemented with mandatory legislations ‡ Department of Geography and Environmental Studies, Adigrat for registration, certification and regular vaccination of University, Adigrat, ET owned dogs; depopulation of stray dogs; creating public § Department of Biomedical Science, College of Health Science, awareness as well as provision of easily accessible and Aksum University, Aksum, Tigray, ET affordable post exposure vaccines for humans [3]. ‖ Department of Soil Resource and Watershed management, College of Agriculture, Aksum University, Shire Campus, Shire, Most human deaths due to rabies occur in develop- Tigray, ET ing countries of Asia and Africa [5]. Of these, Ethiopia Corresponding author: Gebreyohans Gebru ([email protected]) is one of the worst affected [12]. Domestic dogs are the Art. 119, page 2 of 12 Gebru et al: Risk Factors and Spatio-Temporal Patterns of Rabies in Northwestern Tigray principal reservoirs of rabies in Ethiopia [8, 15]. Data on previously reported in other studies conducted at different dog demography is not available and policies for control- settings of Ethiopia [8]. Epidemiological information such ling dog breeding and population are also lacking in the as analysis of risk factors and integrating spatio-temporal country [9]. Besides, dog management is poor and anti- data can play an important role in the prevention and con- rabies dog vaccination is often available to owned dogs trol of rabies. Spatio-temporal human rabies distribution found in urban settings [16]. Large population of dogs has become easier with the development and improve- combined with poor dog management contributes to ment of Geographic Information Systems (GIS), software the high endemicity of canine rabies in the country [15]. systems that visually represent information spatially and Severe under-reporting of human rabies cases and lack of non-spatially on maps. However, little is known about the record keeping have also been reported in Ethiopia [17]. spatio-temporal distribution of disease in Northwestern This has resulted in underestimating the actual burden Tigray, which hinders the implementation of cost-effective of the disease and made it less prioritized for control and disease prevention and control measures. The objectives prevention. Besides, a substantial number of exposed to of this research were, therefore, to give insights into the rabies prefer to seek medical care from traditional heal- risk factors and spatio-temporal patterns of human rabies ers rather than visiting health care centers [18, 19]. Efforts exposure in Northwestern Tigray, Ethiopia. aiming at rabies control are fragmented due to weak coordination between the veterinary and public health Methods sectors. The supply of anti-rabies dog vaccines is also lim- Description of the study area ited and irregular [8]. Even in situations when anti-rabies Health facility study was conducted at Suhul general vaccines are available, owners are not willing to vaccinate hospital based on human PEP data. Dog bite victims their dogs due to lack of awareness [15]. admitted in the hospital were from eight districts of Rabies is an endemic and economically important dis- Northwestern Tigray namely: Shire Endaselassie, Laelay ease with great public health concern in Northwestern Adiabo, Tselemti, Tahtay Adiabo, Asgede Tsimbla, Sheraro, Tigray. A retrospective study conducted at Suhul hos- Medebay Zana and Tahtay Koraro. The hospital is located pital, located in Northwestern Tigray, reported that the at Shire Endaselassie town in Northwestern Tigray annual incidence of human rabies was much higher than (Figure 1). Northwestern Tigray is a zonal administration Figure 1: Location map of the study area. Gebru et al: Risk Factors and Spatio-Temporal Patterns of Rabies in Northwestern Tigray Art. 119, page 3 of 12 with an altitude ranges from 645 to 2852 meters above skin; and minor scratches or abrasions without bleed- sea level. The total area of the zone (in Ethiopia, zone is a ing. large political administrative unit next to regional state) is • Category of exposure type III – Single or multiple estimated to be 18,325 km2 with an average annual rain- transdermal bites or scratches, licks on broken skin; fall of 878 mm, which mainly occurs between June and Contamination of mucous membrane with saliva (i.e. September. Average annual temperature of the area varies licks); and Exposure to bats. from 18 to 34.6°C. More than 40% of Northwestern Tigray • Rabies post exposure prophylaxis (PEP) – rabies PEP is estimated to be covered with forests. It is also one of was administered for category II and III exposures the areas of the Tigray region, where high population of and 17 total doses were given through subcutane- livestock are found. Kafta Sheraro national park, which is ous route around the umbilicus (14 doses for the first the home for 95 avian and 42 mammalian wildlife species, 14 consecutive days and three booster doses on the are also found in this zone. 10th, 20th and 30th days following the last injection). Five percent of aqueous suspension of brain tissue of Identification of human rabies exposure sheep inoculated with fixed rabies virus, inactivated A prospective study was conducted from 01 January 2016 with Phenol (Fermi-Type) was used as PEP. The vaccine to 31 December 2016 (lapsed for one year) at Suhul general is produced by the Ethiopian Health and Nutrition hospital. Dog bite victims admitted to the hospital were Research Institute (EHNRI). The recommended doses purposively selected for the study.

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