Compiled Body of Works in Field Epidemiology.
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Date
2013-05
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Addis Abeba Universty
Abstract
Introduction: Relapsing fever is a recurrent febrile infection caused by various Borrelia spirochetes transmitted either by lice (epidemic louse born relapsing fever LBRF) or by ticks (endemictick born relapsing fever TBRF). It was once a disease of global epidemic importance. However, largely as a result of the demise of the clothing louse Pediculus humanus, it is now restricted to areas where clothing lice are still common place. Two species of Borrelia are associated with a relatively high rate of relapsing fever–related fatality include B recurrentis (the cause LBRF and the focus of this study) and B duttoni (the cause of TBRF). The body louse spreads during direct contact with infected people or indirectly when infested clothing is shared. In the 1st half the 20th century there were 50 million affected by RF with case fatality rates of 10% - 40%. Largest epidemics claimed 1 million lives during World wars I and II. Epidemics have been common in overcrowded situations with poor hygiene; children and women are more affected.Relapsing fever was the 7th most common cause of hospital admission and 5th most common cause of death in Ethiopia in 2004. Laboratory confirmed RF cases were identified in prison camps of Bahirdar and Mekele during civil war in Ethiopia in 1991.Several confirmed cases of RF were identified in Yirgalem town prison in January 2012. The purpose of this investigation was to determine magnitude and etiology of the outbreak, to identify risk factors and risk group and use findings to undertake evidence based interventions.
Methods: Surveillance data of RF from line list and log books were reviewed. Clinical examination of suspect cases was done. Blood samples were taken from suspected cases and laboratory tested using Gimisa stain. Thick blood film was used. A case control study was conducted on 78cases and 108 controls. Data were analyzed using Excel, Epi – Info 3.5.1 and ARC GIS was used to create maps.
Results: From2604 prisoners a total of 831 cases and 1 death registered from January 15 to Feb.14, 2012 in prison and after two weeks, due to relapse, 24 cases were confirmed and treated. The overall attack rate was 32% and case fatality rate 0.12%. Among cases 100% (831) were males and the age range from 15 to 78 years, median age 20, Mode 20 and mean age 22. From total suspected cases 560 (67%) were laboratory tested and 345 (62%) were confirmed cases of relapsing fever as evidenced by presence of Borrelia recurrentis spps. in the thick blood samples tested. From total cases 823(99%), 780 (94%), 771 (93%), 756 (91%) and 20 (2.4%) developed, head ache, vomiting, fever, Chills and jaundice respectively. From respondents of the case control study 29/78(37%) cases and 57/108(53%) took a body bath weekly (OR = 0.52, 95% CI (0.29-0.96) and From total cases 63/ 78 and 101/108 controls were literate, OR=0.29,95%CI (0.1-0.75),the association was also significant. 37/78 cases and 66/108controls wash their clothes weekly (OR = 0.57, 95% CI, (0.30-1.02), whichwas not significant.
Conclusion & Recommendations: Overcrowding, close contact, water shortage and gap in keeping personal hygiene in the prison contributed to the outbreak, The outbreak was contained dueto prompt intervention measures taken and intervention activities were recommended to prevent the emergence of future outbreaks of relapsing fever.
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Keywords
Crowding, Close Contact, Borrelia Recurrentis, Relapsing Fever, Sidama, Ethiopia