Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania

Abstract Background In the past two decades, Rift Valley Fever (RVF) outbreaks have been reported twice in Tanzania, with the most recent outbreak occurring in 2006/07. Given the ecology and climatic factors that support mosquito vectors in the Serengeti ecosystem, we hypothesized a continued transm...

Full description

Bibliographic Details
Main Authors: Abade Ahmed, Jabir Makame, Fyumagwa Robert, Keyyu Julius, Matee Mecky
Format: Article
Language:English
Published: BMC 2018-06-01
Series:BMC Infectious Diseases
Subjects:
Online Access:http://link.springer.com/article/10.1186/s12879-018-3183-9
_version_ 1818340104298561536
author Abade Ahmed
Jabir Makame
Fyumagwa Robert
Keyyu Julius
Matee Mecky
author_facet Abade Ahmed
Jabir Makame
Fyumagwa Robert
Keyyu Julius
Matee Mecky
author_sort Abade Ahmed
collection DOAJ
description Abstract Background In the past two decades, Rift Valley Fever (RVF) outbreaks have been reported twice in Tanzania, with the most recent outbreak occurring in 2006/07. Given the ecology and climatic factors that support mosquito vectors in the Serengeti ecosystem, we hypothesized a continued transmission of RVF virus (RVFV) during interepidemic periods. This study was carried out to determine sero-prevalence, spatial distribution and factors associated with RVF in at-risk agro-pastoral and pastoral communities in the Serengeti Ecosystem in northern Tanzania. Methods A cross sectional study was carried out to establish the general exposure to RVFV by detecting anti–RVFV IgG and anti–RVFV IgM using ELISA techniques. The health facilities where human subjects were blood sampled concurrent with interviews included Bunda District Designated Hospital, Wasso DDH, Endulen hospital, Arash, Malambo, Olbabal, and Piyaya dispenaries (Ngorongoro district) and Nyerere DDH (Serengeti district) respectively. In addition, human subjects from Lamadi ward (Busega district) were recruited while receiving medical service at Bunda DDH. We conducted logistic regression to assess independent risk factor and mapped the hotspot areas for exposure to RVFV. Results A total of 751 subjects (males = 41.5%; females = 58.5%) with a median age of 35.5 years were enrolled at out-patient clinics. Of them, 34 (4.5, 95%CI 3.3–6.3%) tested positive for anti–RVFV IgG. Of the 34 that tested positive for anti–RVFV IgG, six (17.6%) tested positive for anti–RVFV IgM. Odds of exposure were higher among pastoral communities (aOR 2.9, 95% C.I: 1.21–6.89, p < 0.01), and agro-pastoral communities residing in Ngorongoro District (aOR 1.8, 95% C.I 1.14–3.39, p = 0.03). Hotspot areas for exposure to RVFV were Malambo, Olbalbal and Piyaya wards in Ngorongoro district, and Lamadi ward in Busega district. Conclusions The study found both previous and recent exposure of RVFV in humans residing in the Serengeti ecosystem as antibodies against both IgG and IgM were detected. Detection of anti-RVF IgM suggests an ongoing transmission of RVFV in humans during inter-epidemic periods. Residents of Ngorongoro district were most exposed to RVFV compared to Bunda and Serengeti districts. Therefore, the risk of exposure to RVFV was higher among pastoral communities compared to farming communities.
first_indexed 2024-12-13T15:37:35Z
format Article
id doaj.art-3a397799d6174a25ac241a9d246666c1
institution Directory Open Access Journal
issn 1471-2334
language English
last_indexed 2024-12-13T15:37:35Z
publishDate 2018-06-01
publisher BMC
record_format Article
series BMC Infectious Diseases
spelling doaj.art-3a397799d6174a25ac241a9d246666c12022-12-21T23:39:58ZengBMCBMC Infectious Diseases1471-23342018-06-011811810.1186/s12879-018-3183-9Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern TanzaniaAbade Ahmed0Jabir Makame1Fyumagwa Robert2Keyyu Julius3Matee Mecky4Tanzania Field Epidemiology and Laboratory Training Program, Ministry of Health, Community Development, Gender, Elderly and ChildrenTanzania Field Epidemiology and Laboratory Training Program, Ministry of Health, Community Development, Gender, Elderly and ChildrenTanzania Wildlife Research InstituteTanzania Wildlife Research InstituteDepartment of Microbiology and Immunology, Muhimbili University of Health and Allied ScienceAbstract Background In the past two decades, Rift Valley Fever (RVF) outbreaks have been reported twice in Tanzania, with the most recent outbreak occurring in 2006/07. Given the ecology and climatic factors that support mosquito vectors in the Serengeti ecosystem, we hypothesized a continued transmission of RVF virus (RVFV) during interepidemic periods. This study was carried out to determine sero-prevalence, spatial distribution and factors associated with RVF in at-risk agro-pastoral and pastoral communities in the Serengeti Ecosystem in northern Tanzania. Methods A cross sectional study was carried out to establish the general exposure to RVFV by detecting anti–RVFV IgG and anti–RVFV IgM using ELISA techniques. The health facilities where human subjects were blood sampled concurrent with interviews included Bunda District Designated Hospital, Wasso DDH, Endulen hospital, Arash, Malambo, Olbabal, and Piyaya dispenaries (Ngorongoro district) and Nyerere DDH (Serengeti district) respectively. In addition, human subjects from Lamadi ward (Busega district) were recruited while receiving medical service at Bunda DDH. We conducted logistic regression to assess independent risk factor and mapped the hotspot areas for exposure to RVFV. Results A total of 751 subjects (males = 41.5%; females = 58.5%) with a median age of 35.5 years were enrolled at out-patient clinics. Of them, 34 (4.5, 95%CI 3.3–6.3%) tested positive for anti–RVFV IgG. Of the 34 that tested positive for anti–RVFV IgG, six (17.6%) tested positive for anti–RVFV IgM. Odds of exposure were higher among pastoral communities (aOR 2.9, 95% C.I: 1.21–6.89, p < 0.01), and agro-pastoral communities residing in Ngorongoro District (aOR 1.8, 95% C.I 1.14–3.39, p = 0.03). Hotspot areas for exposure to RVFV were Malambo, Olbalbal and Piyaya wards in Ngorongoro district, and Lamadi ward in Busega district. Conclusions The study found both previous and recent exposure of RVFV in humans residing in the Serengeti ecosystem as antibodies against both IgG and IgM were detected. Detection of anti-RVF IgM suggests an ongoing transmission of RVFV in humans during inter-epidemic periods. Residents of Ngorongoro district were most exposed to RVFV compared to Bunda and Serengeti districts. Therefore, the risk of exposure to RVFV was higher among pastoral communities compared to farming communities.http://link.springer.com/article/10.1186/s12879-018-3183-9Rift valleySerengeti ecosystemInter-epidemic humanTanzania
spellingShingle Abade Ahmed
Jabir Makame
Fyumagwa Robert
Keyyu Julius
Matee Mecky
Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
BMC Infectious Diseases
Rift valley
Serengeti ecosystem
Inter-epidemic human
Tanzania
title Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
title_full Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
title_fullStr Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
title_full_unstemmed Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
title_short Sero-prevalence and spatial distribution of Rift Valley fever infection among agro-pastoral and pastoral communities during Interepidemic period in the Serengeti ecosystem, northern Tanzania
title_sort sero prevalence and spatial distribution of rift valley fever infection among agro pastoral and pastoral communities during interepidemic period in the serengeti ecosystem northern tanzania
topic Rift valley
Serengeti ecosystem
Inter-epidemic human
Tanzania
url http://link.springer.com/article/10.1186/s12879-018-3183-9
work_keys_str_mv AT abadeahmed seroprevalenceandspatialdistributionofriftvalleyfeverinfectionamongagropastoralandpastoralcommunitiesduringinterepidemicperiodintheserengetiecosystemnortherntanzania
AT jabirmakame seroprevalenceandspatialdistributionofriftvalleyfeverinfectionamongagropastoralandpastoralcommunitiesduringinterepidemicperiodintheserengetiecosystemnortherntanzania
AT fyumagwarobert seroprevalenceandspatialdistributionofriftvalleyfeverinfectionamongagropastoralandpastoralcommunitiesduringinterepidemicperiodintheserengetiecosystemnortherntanzania
AT keyyujulius seroprevalenceandspatialdistributionofriftvalleyfeverinfectionamongagropastoralandpastoralcommunitiesduringinterepidemicperiodintheserengetiecosystemnortherntanzania
AT mateemecky seroprevalenceandspatialdistributionofriftvalleyfeverinfectionamongagropastoralandpastoralcommunitiesduringinterepidemicperiodintheserengetiecosystemnortherntanzania