Background
Malnutrition is a deficiency state of both macro and micronutrients (under - nutrition) and their over consumption (over- nutrition) causing measurable adverse effects on human body structure and function, resulting in specific physical and clinical outcomes. Little has been known about the seasonal variation in the magnitude of acute child under-nutrition and its determinants in low and middle-income countries making difficult the choice of a better nutrition intervention. The objective of this study was to determine the prevalence of acute under-nutrition and its associated factors on children aged 6 to 36 months in east rural Ethiopia in wet and dry seasons.

Methods
A longitudinal study was conducted on children aged 6 to 36 months and their mothers (mother–child pairs) from July/August 2010/2011 to January/ February 2011/2012 in east rural Ethiopia. Data were collected from 2,132 mother–child pairs using a pretested structured questionnaire and the UNICEF recommended anthropometric measuring instruments after standardization. The Odds Ratio with 95% confidence interval was estimated to identify the predictors of acute child under nutrition (wasting) using a conditional fixed- effects logistic regression.

Results
The prevalence of acute child under-nutrition was 7.4%; 95% CI: (6.3%, 8.5%) in wet and 11. 2%; 95% CI: (9.8%, 12.5%) in dry seasons. Child wasting was more common among children of poor households who had no cooperative bank saving accounts [AOR (95% CI) = 8.2. (1.8, 37.6)], and access to health facilities [AOR (95% CI) = 2.2 (1.4, 3.6)].

Conclusion
Acute child under-nutrition was relatively higher in the dry season. Although season was not significantly associated with child under - nutrition, poverty and poor access to health services were important predictors of wasting in the study setting. Thus, effective community–based nutrition interventions that require a multi - disciplinary approach should be scaled up to curb childhood under-nutrition.