Table 1. Results of the Kuldorff space-time permutation analysis.

Statistical significant was defined by P < 0.05. The clusters identified were associated with non-significant, higher relative risk (Kulldorff, 2015).

Cluster	Coordinates	Radius	Time frame	No. of outbreaks	Expected outbreaks	Observed/Expected	Test statistic	P-value
A	18.999396 S, 28.901210 E	32.95 km	Nov-78 to Dec-78	2	0.087	23	4.4	0.24
B	18.469056 S, 29.444797 E	59.37 km	Sep-79	3	0.26	11.5	4.67	0.055
C	17.507240 S, 30.975851 E	58.94 km	Jan-80	4	0.61	6.57	4.27	0.25
D	20.916667 S, 28.466667 E	83.34 km	Feb-80	3	0.43	6.9	3.3	0.79