Systematic review and meta-analysis of animal listeriosis in Ethiopia

Listeriosis is a widespread zoonotic disease that becomes an important source of food borne infections all over the world. Mostly it affects cattle herd, sheep and goat fl ocks. The objective of the research was to estimate prevalence of Listeriosis in Ethiopia and to provide the distribution of the disease at national level. The metaanalysis was conducted to collect the information and to provide a pooled prevalence estimate at national level and identify potential predictors. The secondary data were searched from Published research and review written by English language during the period between October, 2000 and June 2018. The publications were selected based on inclusive and exclusion criteria for data extraction and analysis by Meta-Analysis Software Relevant animal level data on 1460 was collected from 14 published manuscripts and one master’s thesis resulting conformed to predefi ned criteria. The dataset was analyzed using a meta-analytical technique. The pooled prevalence assessed computed for listeriosis problem was 23.9% with confi dence interval of 17.6, 30.2. Among the predictors considered for heterogeneity analysis only sample size and listeriosis the prevalence was showed to decrease with increasing sample size. This study showed occurrence of animal listeriosis at national level. Thus, approach used to know the prevalence of the disease at national level. Research article Systematic review and metaanalysis of animal listeriosis in Ethiopia Sagni Diba* and Habtamu Terefe Ministry of Agriculture, Addis Ababa, Ethiopia Received: 10 March, 2021 Accepted: 05 April, 2021 Published: 06 April, 2021 *Corresponding author: Segni Diba, Ministry of Agriculture, Addis Ababa, Ethiopia, Email:


Introduction
Listeriosis is unimportant emerging food borne of bacterial zoonotic infections in worldwide [1]. It is occurred in 1920 for the fi rst time as an infectious disease of rodents and small animals [2]. From listeria species L. monocytogenes primarily affects older, adults, pregnant women, and newborns with weakened immune systems [3]. Because ingested with poorly preserved silage and contamination of food in animal (unfermented feed) and human, absences of acidity enough to kill the bacteria [4].
Epidemiological distribution of Listeriosis changing now a day, the pathogen has been occurred some has spread in Ethiopia. In different part of country the study were reported in different area with different prevalence [5,6]. The areas in which the disease is distributed are specially established at central the part of the country [7]. From those towns Bishoftu and Selale are well known because growth in the dairy industry [8].
Animal products and poultry were sources of infection. From listeria species L. monocytogenes in human well known on the status of food borne listeriosis [3].The general symptom of the disease was fever, watery diarrhea, nausea, headache, and pain in joints and muscles [9]. The diagnosis methods of disease are Oxford agar, isolation of agents, FA, inoculation, serological technique, and Molecular methods [10]. Combination of antibiotics used for treatment of the disease [11]. Good hygienic practice and proper bio-security was the control methods of disease [12].
The listeriosis is bacterial zoonotic in both veterinary and human's pathogen. In Veterinary the bacteria causes basilar meningitis and still birth, Although in human pathogen causes infection especially immune suppressed, elder, pregnant human population [13]. Economically the disease importance to loss of production due to abortion, treatment cost, reduces trade of animal [14,15]. In Ethiopia Contamination of animal products considered as a sources of disease. There does not know the pooled prevalence to assess the distribution of Listeria species in the country level. Therefore, the quantitative synthesis of research assessed important to know level of disease distribution. The objective of the study was to estimate prevalence of disease in by meta-analysis software and to provide good distribution of the disease at national level.

Study protocol
Study standard was collecting secondary data and categorized inclusion and exclusion criteria. Two types of guidelines and a data extraction method were developed. The primarily was a standard for preliminary screening depends on title of research and abstract contents. The second standard included specifi c criteria to assist in categorized valid studies that were in line with the objective of the study. The approach ensured compliance with PRISMA guideline for review processes [16].

Literature search
Electronic secondary data search methods were used.
Key words such as "Listeria species", or "L. monocytogenes", "food of animal origin", "antimicrobials susceptibility of listeria species" or "bovine milk" or "Dairy farms operational

Inclusion and exclusion criteria
The criteria for identifying Ethiopian authors were

Data extraction and quality assessment
The standard for collection methods depends; name of the author, year of publication, species affected, region, sample size, number positives, number negatives, prevalence and respective 95 % CI. Extracted data were written on Excel sheet.

Meta analysis
Descriptive statistics were applied to determine the total number species included at each level of analysis [17]. Randomeffects model was used to pool the estimations. Outcomes were the total prevalence of listeriosis in Ethiopia. Results of the meta-analysis were shown as a forest plot diagram. Q-test and I 2 statistics were used to examine heterogeneity of studies.
Subgroup metaanalysis was utilized to estimate the pooled prevalence of CE in small ruminants by stratifying the species.
STATA-11 software and meta-prop one described on were used to analysis.

Publication bias assessment
Funnel plots were used to obtain visual impressions acrossstudy bias. Begg's and Egger's tests were used to assess the statistical signifi cance of the bias noted [18].

Literature search results
Literature search results by using the secondary data from internet and manual search resulted in 48 published researches and master's research. 29 of them were totally failed due to criteria.
During inspection of the individual thesis, 5 of them had lack of methodology; others are due to sampling methods and study design that forced us to question the internal validity of the estimates for the study population. Finally 13 published articles and one master's thesis met used based on the criteria; Ethiopian authors, written only in English language, their objective, study design, sampling methods, year of publication, data analysis and presentation were the minimum acceptable standard to be included in this review ( Figure 1).

Meta-analysis
The pooled prevalence estimate of listeria infection was 23.9% with 95% CI: 17.6, 30.2. In a random effect model, the calculated Cochran value (Q) was 387.39 (df = 12 and p=0.000).
The raw and logit-transformed effect size distribution is given on. The effect size and respective weight of each eligible study report in the review is also presented the forest plot ( Figure   2). The variation among studies was signifi cant attributable to heterogeneity between studies. The magnitude of this true variation is high (I 2 = 96.9%).

Publication bias assessment
In the publication bias analysis based on the Begg's and Egger's statistics were seen to have p value=0.000. The parameters were consistent with what is observed on the funnel plot ( Figure 3) and suggests the presence of bias to the right side that could be linked to more study reports with higher prevalence estimate. In Ethiopia, prevalence of the listeosis is well established.

Discussion
Hence the real causes of these differences in the prevalence of the listeria species are clear for all the population of animals.
The prevalence of listeriosis is common in the farm level as study reported by Garedew et al., 2015 in Gonder. Listeria prevalence was high in meat and milk. However, the study shows all prevalence from the animal products not live [11].
Infection may result in an obvious clinical disease, such that the affected animals may not be marketable [13].
listeria transmission due to direct contact between animals and human due to poor hygiene. Investigators reported listeria monocytegen is more common in the area of country than other listeria species. Besides, more of farm sourced of the disease than other animals relatively.
There are Limitations in our analysis fi rst; due to lack of study on listeria species in many regions of the country.
Secondly the fi nding not fully indicates the prevalence of the disease in country because the prevalence of listeria species has not yet been surveyed in many studies conducted in Ethiopia.
Third heterogeneity was detected among the included studies therefore the results should be interpreted with caution.

Conclusion and recommendation
The study to show the distribution of the disease in country level and to shows the status of the disease especially epidemiological evidence. The disease affected humans due to sources of contamination for susceptible groups. In addition, as explained above L. monocytogenes is proved to be sensitive to many and available drugs. So, appropriate drug selection for Listeriosis and checking for effectiveness must be made as routine way in food microbiology laboratories.