Modelling the ecological niche of hookworm in Brazil based on climate
Date
2012
Authors
Mudenda, Ntombi B.
Malone, John B.
Kearney, Michael T.
Mischler, Paula D.
Nieto, Prixia del Mar
McCarroll, Jennifer C.
Vounatsou, Penelope
Journal Title
Journal ISSN
Volume Title
Publisher
Geospatial Health
Abstract
. The distribution of hookworm in schistosomiasis-endemic areas in Brazil was mapped based on climate suitability.
Known biological requirements of hookworm were fitted to data in a monthly long-term normal climate grid (18 x 18 km)
using geographical information systems. Hookworm risk models were produced using the growing degree day (GDD) water
budget (WB) concept. A moisture-adjusted model (MA-GDD) was developed based on accumulation of monthly temperatures
above a base temperature of 15 °C (below which there is no lifecycle progression of Necator americanus) conditional
on concurrent monthly values (rain/potential, evapotranspiration) of over 0.4. A second model, designated the gradient
index, was calculated based on the monthly accumulation of the product of GDD and monthly WB values (GDD x WB).
Both parameters had a significant positive correlation to hookworm prevalence. In the northeastern part of Brazil (the
Caatinga), low hookworm prevalence was due to low soil moisture content, while the low prevalence in southern Brazil was
related to low mean monthly temperatures. Both environmental temperature and soil moisture content were found to be
important parameters for predicting the prevalence of N. americanus.
Description
Journal article
Keywords
Hookworm, , Necator americanus , Risk models , Growing degree days , Geographical information systems , Water budget