Malaria outbreak was investigated in Laelay Adyabo district northern Ethiopia. The overall attack rate was 12.1 cases per 1000 population, this finding was lower than a study done in Asgede Tsimbla district, Ethiopia (attack rate: 22.3) and India (attack rate: 15.1) [14, 21] but greater than a study done in Pakistan (attack rate: 0.9) [22]. The low attack rate in this study might be attributed to area difference in the burden of malaria and duration of the illness. This area is known as low transmission area for malaria and the duration of illness was short compared to other studies [7, 23, 24].
Median age of malaria patients were 16 years, which is in line with outbreak investigation done in Ankesha and Asgede Tsimbla districts, Ethiopia [10, 14], but younger than the study done in Guna Yala, Panama where the median age was 25 years [25]. This might be due to majority of the adolescents were spending more time outdoors in this area for agricultural and livestock keeping activities [6].
Most of the patients (72%) were males, this is also similar with the studies done in Ethiopia (Ziway and Amhara region pilot study), but higher than a study done in India (50.6%) and Ethiopia (Asgede Tsimbla (58%) and Bunga (69%)) [6, 13, 14, 23]. This could be due to the reason that males were more likely engaged in agricultural, livestock keeping and traditional gold mining activities than females in our study area than the other studies. Most of male adolescent population in those Kebelles engaged on traditional gold mining, most of the summer period stays outdoor overnight and also during the study period there was interruption of rain fall. This implies that the regional health bureau needs to give more focus and extend medical services to people who are engaged in agriculture, livestock keeping and traditional gold mining.
In this study most of the cases were caused by Plasmodium falciparum (86.9%). This is similar with the previous year report of the district and by Tigray regional health bureau report. This result also similar with the study done in Asgede Tsimbla and Setit Humera, Ethiopia [3, 7, 13, 14]. As the species of Plasmodium were identified by microscope and rapid diagnostic test the high amount of Plasmodium falciparum could be due to the areas which are in the same region.
Peoples who wore protective cloth at night, knowing about malaria mode of transmission, and availability of waste collection material in their house were less likely to be diseased than those who didn’t wore protective cloth at night, less knowledgeable on mode of transmission, and have waste collection material in their houses. This is consistent with the study done in Zimbabwe [11]. But it is different from the studies conducted in Ameya and Asgede Tsimbla districts of Ethiopia [9, 14]. This may be due to the difference in study period and malaria intervention measures of the study areas which is in our area the health personnel’s were educated the community about malaria mode of transmission and prevention modalities [3, 4, 7, 9, 13, 14]. These findings indicate that comprehensive awareness creation measures on prevention and transmission modalities of malaria are required to mitigate the outbreak effectively.
Those who had mosquito breeding site around their houses were more likely to be diseased by malaria than those who didn’t have mosquito breeding site. This is similar with study done in Ankesha, Ameya, Setit Humera, and Asgede Tsimbla districts of Ethiopia [9, 10, 13, 14]. This could be due to the presence of mosquito breeding site that created suitable condition for reproduction of mosquito and infecting more people since most of the populations stayed out door during the night. The other reason might be due to availability of more stagnant waters and other suitable factors for mosquito breeding sites due to an interruption of rainfall during the study period. Also it could be due to the fact that most of the populations were engaged in outdoor activities especially during the study period. To control malaria outbreak, mosquito breeding sites need to be cleared by involvement of the local community.
In the study those who developed malaria were three times staying out door overnight than those who didn’t develop malaria. This is consistent with the study done in India, Setit Humera, and Asgede Tsimbla districts of Ethiopia [13,14,15]. This may be due to the fact that mosquitos were abundant during night and most of the peoples were not using any protective modalities during night and less use of ITNs outside their home. This indicated that the local health office should educate people staying out-door to use protective modalities.
Limitations of the study include that health facilities registration book didn’t record all relevant variables and that there were no malaria data during the past 5 years which was the best to set baseline levels of malaria cases; thus, the assessment of an outbreak was done based on doubling the previous year in similar weeks.
Conclusions and recommendation
The overall attack rate for malaria during this outbreak was high affecting > 1% of the population. This malaria outbreak was mostly affected for those male populations and residence in Zelazle Kebelle. Even though there are efforts to eliminate malaria in low transmission areas, the factors responsible to maintain malaria were not well controlled. Factors including presence of mosquito breeding sites around the home, staying outdoor overnight, wearing protective close during night, good knowledge on malaria mode of transmission, and presence of waste collection material at home are predictors of the infection.
Therefore, further creation of awareness to the community on malaria mode of transmission and prevention modalities and empowerment of community on their environmental cleanness may mitigate malaria outbreak. The local health workers and decision makers better to keep clean environment by empowering the community themselves and also better to create prevention modalities like preventive cloths and another insecticidal repellents to those outdoor at the night population and to people of special need.
