Abstract
Epidemics of konzo have occurred during severe droughts in parts of east, central, and southern Africa since the 1920s. Occurrence is attributed to exposure to cyanide from poorly processed cassava foods, the sole source of calories when other food crops fail. El Nino, the warm phase of the El Nino-Southern Oscillation (ENSO), induces severe droughts in the geographical areas of Africa where epidemics of konzo occur. Climate regimes are determined by modes of Pacific Decadal Oscillation, which modulates the ENSO. Study was done to determine the relationship of konzo epidemics to climate regimes and phases of ENSO, and to propose a model to explain while konzo epidemics do not occur in all drought affected areas. Data of all konzo epidemics in the past century and in DR Congo from 1974–1996, and indices of ENSO and PDO from 1915 to 2014 were obtained. Konzo epidemics were mapped to phases of ENSO and PDO. Wavelet spectral and wavelet spectral coherence analysis of climate indices and konzo epidemics were done. All konzo epidemics of the past century occurred during warm climate regimes. Of 19 warm phases of ENSO from 1974–1996 in DR Congo, 17 were coupled to konzo epidemics, while of 4 cold phases of ENSO, 1 was coupled to konzo epidemic, odds ratio 26 (95 % CI, 2–378). Global spectral of ENSO and konzo showed dominant periodicity of 5 years, while spectograms showed significant periodicities and coherence between 3–6 years. Spatial distribution of konzo is restricted to the area of maximal impact of El Nino on precipitation in Africa. El Nino is the underlying cause of konzo epidemics. Control of konzo epidemics requires management of the impact of El Nino on agriculture in areas where the population depends on cassava as sole source of calories during droughts. There is the need to develop forecast models of changes in cassava production to predict likely periods of konzo epidemics.
Highlights
Konzo is a neurological syndrome of spastic paraparesis or quadriparesis, dysarthria, impaired visual acuity, and nystagmus (Ministry of Health Mozambique, 1984; Howlett et al, 1990)
Konzo epidemics of late 1920s to late 1940s and of 1978–2005 all occurred during the warm regimes of Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillation (ENSO), while no epidemics were documented during the cold regime from 1942 to 1975
In conclusion it is shown that konzo epidemics and ENSO are coupled on interannual and multidecadal timescales
Summary
Konzo is a neurological syndrome of spastic paraparesis or quadriparesis, dysarthria, impaired visual acuity, and nystagmus (Ministry of Health Mozambique, 1984; Howlett et al, 1990). Disabling spastic paraparesis is the residual deficit in most subjects (Ministry of Health Mozambique, 1984). Major konzo epidemics occurred during severe droughts from the late 1920s to late 1940s (Trolli, 1939; Vileu, 1942; Lucasse, 1952), and from the late 1970s to early 2000s (World Health Organisation, 1982; Ministry of Health Mozambique, 1984; Tylleskar et al, 1991; Ciglenecki et al, 2011; Mlingi et al, 2011). Cassava (Manihot Esculenta Crantz), a drought resistant and cyanogenic food crop, was the main or only source of calories during konzo epidemics. Konzo epidemics occur during low precipitation (Oluwole, 2015b), interannual changes in precipitation alone will not explain the absence of major konzo epidemics between the 1950s and mid-1970s
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
