Investigation of the high rates of extrapulmonary tuberculosis in Ethiopia reveals no single driving factor and minimal evidence for zoonotic transmission of Mycobacterium bovis infection

Abstract

BackgroundEthiopia, a high tuberculosis (TB) burden country, reports one of the highest incidence rates of extra-pulmonary TB dominated by cervical lymphadenitis (TBLN). Infection with Mycobacterium bovis has previously been excluded as the main reason for the high rate of extrapulmonary TB in Ethiopia.MethodsHere we examined demographic and clinical characteristics of 953 pulmonary (PTB) and 1198 TBLN patients visiting 11 health facilities in distinct geographic areas of Ethiopia. Clinical characteristics were also correlated with genotypes of the causative agent, Mycobacterium tuberculosis.ResultsNo major patient or bacterial strain factor could be identified as being responsible for the high rate of TBLN, and there was no association with HIV infection. However, analysis of the demographic data of involved patients showed that having regular and direct contact with live animals was more associated with TBLN than with PTB, although no M. bovis was isolated from patients with TBLN. Among PTB patients, those infected with Lineage 4 reported “contact with other TB patient” more often than patients infected with Lineage 3 did (OR = 1.6, CI 95% 1.0-2.7; p = 0.064). High fever, in contrast to low and moderate fever, was significantly associated with Lineage 4 (OR = 2.3; p = 0.024). On the other hand, TBLN cases infected with Lineage 4 tended to get milder symptoms overall for the constitutional symptoms than those infected with Lineage 3.ConclusionsThe study suggests a complex role for multiple interacting factors in the epidemiology of extrapulmonary TB in Ethiopia, including factors that can only be derived from population-based studies, which may prove to be significant for TB control in Ethiopia.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-0846-7) contains supplementary material, which is available to authorized users.

Profile and treatment outcomes of patients with tuberculosis in Northeastern Ethiopia: A cross sectional study

“…This agreed with different findings reported in Ethiopia and aboard 5,[10][11][12][13] . The possible reason might be related with, lower rates of notification of TB among women than men due to low health seeking behavior, lack of financial control and stigma associated with being TB positive 2 .…”

“…The other justification goes in line with Berg et al, study justified that regular and direct contact with live animals, was a significant risk factor for EPTB 21 . These factors also seem likely, because, people in the study area are known live stock keepers and due to their local tradition, most of their domestic animals shared human shelter.…”

Treatment outcomes of tuberculosis patients under directly observed treatment short-course at Debre Tabor General Hospital, northwest Ethiopia: nine-years retrospective study

“…This might be due to the statistical pooling effect of the reference groups. In contrast to our study, other studies have shown an association between HIV co-infection and TB treatment outcome [27,35].…”

“…However, there are similar reports showing lower notification rates of PTB+ cases and high numbers of EPTB cases in the northern part Ethiopia [3, 13-15, 25, 26]. The causes for this are not yet identified and some reports suggest that it might have something to do with the host genomic base, but this needs further investigation [27]. On top of this, due to limited resources, most of the health facilities in Ethiopia have been using AFB microscopy, which has low sensitivity (40-45%) and might contribute to lower notification rates of PTB+ (observation).…”

Breaking Transmission with Vaccines: The Case of Tuberculosis

“…However, some particular M. bovis strains have adapted to the human host with the ability to transmit between immune-compromised individuals, as discussed later in this chapter. Even in countries with a very high incidence of livestock TB caused by M. bovis and high incidence rates of extrapulmonary TB in humans, human infection with M. bovis is excluded, as different lineages of M. tuberculosis are considered responsible for extrapulmonary TB (7).…”