Mapping as a tool for predicting the risk of anthrax outbreaks in Northern Region of Ghana.
BACKGROUND
Anthrax is a febrile soil-born infectious disease that can affect all warm-blooded animals including man. Outbreaks of anthrax have been reported in northern region of Ghana but no concerted effort has been made to implement risk-based surveillance systems to document outbreaks so as to implement policies to address the disease. We generated predictive maps using soil pH, temperature and rainfall as predictor variables to identify hotspot areas for the outbreaks.


METHODS
A 10-year secondary data records on soil pH, temperature and rainfall were used to create climate-based risk maps using ArcGIS 10.2. The monthly mean values of rainfall and temperature for ten years were calculated and anthrax related evidence based constant raster values were created as weights for the three factors. All maps were generated using the Kriging interpolation method.


RESULTS
There were 43 confirmed outbreaks. The deaths involved were 131 cattle, 44 sheep, 15 goats, 562 pigs with 6 human deaths and 22 developed cutaneous anthrax. We found three strata of well delineated distribution pattern indicating levels of risk due to suitability of area for anthrax spore survival. The likelihood of outbreaks occurrence and reoccurrence was higher in Strata I, Strata II and strata III respectively in descending order, due to the suitability of soil pH, temperature and rainfall for the survival and dispersal of B. anthracis spore.


CONCLUSIONS
The eastern corridor of Northern region is a Hots spot area. Policy makers can develop risk based surveillance system and focus on this area to mitigate anthrax outbreaks and reoccurrence.
Veterinary Services Directorate Tamale, P.O. Box 241, Tamale, Northern Region, Ghana; Ghana Field Epidemiology and Laboratory Training Programme, Tamale, Northern Region, Ghana.
Ayamdooh Evans
AE
Nsoh
University of Ghana, College of Health Sciences, School of Public Health, Accra, Ghana.
Ernest
E
Kenu
Rudan Engineering Limited, 156 Atomic-Haatso Road, P.O. Box CT 828, Cantonments, Accra, Ghana.
Eric Kofi
EK
Forson
Ghana Field Epidemiology and Laboratory Training Programme, Tamale, Northern Region, Ghana.
Edwin
E
Afari
Ghana Field Epidemiology and Laboratory Training Programme, Tamale, Northern Region, Ghana.
Samuel
S
Sackey
Ghana Field Epidemiology and Laboratory Training Programme, Tamale, Northern Region, Ghana.
Kofi Mensah
KM
Nyarko
University of Ghana, School of Public Health, Accra, Ghana.
Nathaniel
N
Yebuah
D000820:Animal Diseases / Q000453:epidemiology; D000818:Animals; D000881:Anthrax / Q000453:epidemiology* / Q000662:veterinary; D001408:Bacillus anthracis / Q000302:isolation & purification*; D002417:Cattle; D002980:Climate; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005869:Ghana / Q000453:epidemiology; D006041:Goats; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011159:Population Surveillance; D011891:Rain; D012306:Risk; D012756:Sheep; D017192:Skin Diseases, Bacterial / Q000453:epidemiology*; D012987:Soil; D012988:Soil Microbiology; D013552:Swine; D013696:Temperature
D012987:Soil
Anthrax; B. anthracis; Northern Region; outbreak; rainfall; soil pH; spatial risk mapping; surveillance; temperature