Etiology of Bacterial Meningitis in Ethioia, 2007 - 2011 : A Retrospective Study

Abstract

Bacterial meningitis is a serious infection and is associated with considerable mortality and morbidity in various parts of the world. It has a global epidemiology but sub-Saharan Africa bears the highest burden of the disease. Located in the eastern horn of Africa, Ethiopia is also endemic for bacterial meningitis with frequent meningococcal epidemics occurring every few years particularly in the dry season from December to June. Although it is generally considered a disease of the childhood, no age group is exempt from the infection. In the developing countries the fatality rate associated with bacterial meningitis can often be very high. In the absence of proper treatment, bacterial meningitis is known to cause serious neurological complications which may persist throughout the life. Bacterial meningitis has remained a serious health concern for Ethiopia for the past few decades. Formulation of effective preventive strategies can only be based on the estimates of the recent epidemiological trends of bacterial meningitis. The study conducted focuses primarily on the recent trends of the disease in two major cities of Ethiopia i.e. Gondar and Awassa. The data collected retrospectively from the hospitals’ clinical and laboratory records provide an insight into the epidemiology, demographical characteristics such as age-wise and sex-wise distribution of the disease, seasonal variation of the etiological agents and the treatment outcomes of bacterial meningitis in Ethiopia. The bacterial cultures of the cerebrospinal fluid (CSF) and the Gram staining results from the past five years were studied to find out the estimated prevalence of the common agents of bacterial meningitis. The clinical records from the hospital wards provided insight into the various common clinical signs and symptoms associated with bacterial meningitis and the treatment outcomes including the various common complications of the disease. The study showed a higher prevalence of bacterial meningitis in males with an observed male to female ratio of 1.7:1 at Gondar and 1.9:1 at Awassa. The disease incidence was highest in small children and young adults. Infants were the most commonly affected age group at Gondar University Hospital which formed almost 27% of the cases. Young adults between 15-24 years of age were among the most effected age groups at Awassa Referral Hospital and also accounted to about 27% of the cases. A marked effect of seasonal variation was observed with more cases occurring in the summer months. Almost 35% of the cases of bacterial meningitis at Gondar were recorded in the months of May and June. Culture specific results show that this variation was most pronounced in meningococcal disease in which almost 2/3 of the cases (67%) occurred in the dry season during the second quarter of the year i.e. April to June. Among the various agents of bacterial meningitidis, Streptococcus pneumoniae was the most common organism which was identified in the CSF cultures of 35 patients (35.3%). This was followed by Neisseria meningitidis from 27 cases (27.3%) and Haemophilus influenzae from 9 cases (9.1%). In the absence of laboratory facilities the diagnosis of bacterial meningitis largely depends upon the clinical signs and symptoms at the time of presentation. The most common clinical symptoms that were recorded from the clinical records of Awassa Referral Hospital include high grade fever (88.9% of the cases), neck rigidity (74.8%), headache (69.6%) and nausea and vomiting (59.3%). Altered mental state was present in more than half of the patients. Various treatment outcomes were recorded including complete recovery (56.7%), partial recovery with sequelae (9.2%) and death which was recorded in 23.5% of the cases. The study had been conducted with the aim to provide data that will be useful for formulation and implementation of preventive strategies against bacterial meningitis in Ethiopia. The results represent two major and demographically distinct cities of Ethiopia. These results can be generalized to give estimate of the recent trends and the current prevalence of bacterial meningitis in Ethiopia which may provide basis for future research not only in these study sites but also in other cities of Ethiopia.