Background Rift Valley fever (RVF)-like disease was first reported in Tanzania more than eight decades ago and the last large outbreak of the disease occurred in 2006–07. This study investigates the spatial and temporal pattern of RVF outbreaks in Tanzania over the past 80 years in order to guide prevention and control strategies. Materials and Methods A retrospective study was carried out based on disease reporting data from Tanzania at district or village level. The data were sourced from the Ministries responsible for livestock and human health, Tanzania Meteorological Agency and research institutions involved in RVF surveillance and diagnosis. The spatial distribution of outbreaks was mapped using ArcGIS 10. The space-time permutation model was applied to identify clusters of cases, and a multivariable logistic regression model was used to identify risk factors associated with the occurrence of outbreaks in the district. Principal Findings RVF outbreaks were reported between December and June in 1930, 1947, 1957, 1960, 1963, 1968, 1977–79, 1989, 1997–98 and 2006–07 in 39.2% of the districts in Tanzania. There was statistically significant spatio-temporal clustering of outbreaks. RVF occurrence was associated with the eastern Rift Valley ecosystem (OR = 6.14, CI: 1.96, 19.28), total amount of rainfall of >405.4 mm (OR = 12.36, CI: 3.06, 49.88), soil texture (clay [OR = 8.76, CI: 2.52, 30.50], and loam [OR = 8.79, CI: 2.04, 37.82]). Conclusion/Significance RVF outbreaks were found to be distributed heterogeneously and transmission dynamics appeared to vary between areas. The sequence of outbreak waves, continuously cover more parts of the country. Whenever infection has been introduced into an area, it is likely to be involved in future outbreaks. The cases were more likely to be reported from the eastern Rift Valley than from the western Rift Valley ecosystem and from areas with clay and loam rather than sandy soil texture.
References
[1]
Flick R, Bouloy R (2005) Rift Valley Fever Virus. Curr. Mol. Med 5: 827–834. doi: 10.2174/156652405774962263
Rich KM, Wanyoike F (2010) An assessment of the regional and national socioeconomic impacts of the 2007 Rift Valley fever outbreak in Kenya. Am J Trop Med Hyg 83: 52–57. doi: 10.4269/ajtmh.2010.09-0291
[4]
Dar O, McIntyre S, Hogarth S, Heymann D (2013) Rift Valley fever and a new paradigm of research and development for zoonotic disease control. Emerg Infect Dis. 19(2): 189–193. doi: 10.3201/eid1902.120941
[5]
Chevalier V, Lancelot R, Thiongane Y, Sall B, Diaite A, et al. (2005) Rift Valley fever in small ruminants, Senegal, 2003. Emerg Infect Dis 11: 1693–1700. doi: 10.3201/eid1111.050193
[6]
Morvan J, Rollin PE, Laventure S, Rakotoarivony I, Roux J (1992) Rift Valley fever epizootic in the central highlands of Madagascar. Res Virol 143: 407–415. doi: 10.1016/s0923-2516(06)80134-2
[7]
Shoemaker T, Boulianne C, Vincent MJ, Pezzanite L, Al-Qahtani MM, et al. (2002) Genetic analysis of viruses associated with emergence of Rift Valley fever in Saudi Arabia and Yemen, 2000–2001. Emerg Infect Dis 12: 1415. doi: 10.3201/eid0812.020195
[8]
Balkhy HH, Memish ZA (2003) Rift Valley fever: an uninvited zoonosis in the Arabian Peninsula. International Journal of Antimicrobiological Agents 21: 153–7. doi: 10.1016/s0924-8579(02)00295-9
[9]
Hartley DM, Rinderknecht JL, Nipp TL, Clarke NP, Snowder GD (2011) National Centre for Foreign Animal and Zoonotic Disease Defense Advisory Group. Potential effects of Rift Valley fever in the United States. Emerg Infect Dis 17. Available: http://dx.doi.org/10.3201/eid1708.101088. Accessed 13 May 2013.
[10]
European Food Safety Authority (2005) Opinion of the Scientific Panel on Animal Health and Welfare on a request from the commission related to the risk of a Rift Valley fever incursion and its persistence within the community. European Food Safety Authority Journal 238: 1–128.
[11]
Versteirt V, Ducheyne E, Schaffner F, Hendrickx G (2013) Systematic literature review on the geographic distribution of Rift Valley Fever vectors in the Europe and the neighbouring countries of the Mediterranean Basin. Supporting Publications. Available: www.efsa.europa.eu/publications. Accessed 13 May 2013.
[12]
Pepin M, Bouloy M, Bird B, Kemp A, Paweska J (2010) Rift Valley fever virus (Bunyaviridae: Phlebovirus): an update on pathogenesis, molecular epidemiology, vectors, diagnostics and prevention, Veterinary Research. 41: 61 DOI: 10.1051/vetres/2010033.
[13]
Grobbelaar AA, Weyer J, Leman PA, Kemp A, Paweska JT, et al. (2011) Molecular epidemiology of Rift Valley fever virus. Emerg Infect Dis. 12: 2270–76. doi: 10.3201/eid1712.111035
[14]
Murithi RM, Munyua P, Ithondeka PM, Macharia JM, Hightower A, et al. (2011) Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districs. Epidemiol Infect. 139: 372–80. doi: 10.1017/s0950268810001020
[15]
LaBeaud AD, Ochiai Y, Peters CJ, Muchiri EM, King CH (2007) Spectrum of Rift Valley fever virus transmission in Kenya: insight from three distinct regions. J Trop Med Hyg. 76: 795–800.
[16]
Bird BH, Githinji JWK, Macharia JM, Kasiiti JL, Muriithi RM, et al. (2008) Multiple virus lineages sharing recent common ancestry were associated with a large Rift Valley fever outbreak among livestock in Kenya during 2006–2007. J Virol. 111: 52–66. doi: 10.1128/jvi.01519-08
[17]
Nderitu L, Lee JS, Omolo J, Omulo S, O’Guinn ML, et al. (2011) Sequential Rift Valley fever outbreaks in Eastern Africa caused by multiple lineages of the virus. J Infect Dis. 203: 655–65. doi: 10.1093/infdis/jiq004
[18]
Evans A, Gakuya F, Paweska JT, Rostal M, Akoolo L, et al. (2008) Prevalence of antibodies against Rift Valley fever virus in Kenyan wildlife. Epidemiol Infect 136: 1261–1269 doi:10.1017/S0950268807009806.
[19]
Desirée LaBeaud A, Bashir F, King CH (2011) Measuring the burden of arboviral diseases: the spectrum of morbidity and mortality from four prevalent infections. Population Health Metrics 9: 1. doi: 10.1186/1478-7954-9-1
[20]
Britch SC, Binepal YS, Ruder MG, Karithi HM, Linthicum KJ, et al. (2013) Rift Valley fever risk map model and seroprevalence in selected wild ungulates and camels from Kenya. PLoS ONE. 8(6): e66626. doi: 10.1371/journal.pone.0066626
[21]
Cêtre-Sossah C, Pédarrieu A, Guis H, Defernez C, Bouloy M, et al. (2012) Prevalence of Rift Valley Fever among Ruminants, Mayotte. Emerging Infectious Diseases 18: 6 DOI:10.3201/eid186.111165.
[22]
Fafetine J, Neves L, Thompson PN, Paweska JT, Rutten VPMG, et al. (2013) Serological Evidence of Rift Valley Fever Virus Circulation in Sheep and Goats in Zambézia Province, Mozambique. PLoS Negl Trop Dis 7(2): e2065 doi:10.1371/journal.pntd.0002065.
[23]
Heinrich N, Saathoff E, Weller N, Clowes P, Kroidl I, et al. (2012) High Seroprevalence of Rift Valley Fever and evidence for endemic circulation in Mbeya Region, Tanzania, in a cross-sectional study. PLoS Negl Trop Dis 6(3): e1557 doi:10.1371/journal.pntd.0001557.
[24]
Poourrut X, Nkoghe D, Souris M, Paupy C, Paweska J, at al (2010) Rift Valley fever seroprevalence in human rural populations of Gabon. PLoS Negl Trop Dis. 4: e763. doi: 10.1371/journal.pntd.0000763
[25]
Swanepoel RCJ (1994) Rift Valley fever in JAW Coetzer GR, Thompson RD Tustin (eds.), Infectious diseases of Livestock with special reference to southern Africa. 688？717, Oxford University Press, Cape Town.
[26]
Archer BN, Thomas J, Weyer J, Cengimbo A, Essoya LD, et al. (2013) Epidemiological investigations into outbreaks of Rift Valley fever in humans, South Africa, 2008–2011. Emerg Infect Dis 19(2): 1918–25.
[27]
Mohamed M, Mosha F, Mghamba J, Zaki SR, Shieh W-J, et al. (2010) Epidemiologic and clinical aspects of a Rift Valley fever outbreak in humans in Tanzania, 2007. Am J Trop Med Hyg 83 (Suppl. 2)S22–7. doi: 10.4269/ajtmh.2010.09-0318
[28]
Nguku P, Sharif SK, Mutonga D, Amwayi S, Omolo J, et al. (2010) An investigation of a major outbreak of Rift Valley fever in Kenya: 2006–2007. Am J Trop Med Hyg 83 (Suppl. 2)S5–13. doi: 10.4269/ajtmh.2010.09-0288
[29]
Paweska JT, Burt FJ, Swanepoel R (2005) Validation of IgG-sandwich and IgM-capture ELISA for the detection of antibody to Rift Valley fever virus in humans. Journal of Virological Methods 124: 173–181. doi: 10.1016/j.jviromet.2004.11.020
[30]
Paweska JT, Van Vuren PJ, Swanepoel R (2007) Validation of an indirect ELISA based on a recombinant nucleocapsid protein of Rift Valley fever virus for the detection of IgG antibody in humans. Journal of Virology Methods 146: 119–124. doi: 10.1016/j.jviromet.2007.06.006
[31]
Paweska JT, Burt FJ, Anthony F, Smith SJ, Grobbelaar AA, et al. (2003) IgG sandwich and IgM-capture enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in domestic ruminants. J Virol Methods 113: 103–112. doi: 10.1016/s0166-0934(03)00228-3
[32]
Paweska JT, Smith SJ, Wright IM, Willliams R, Cohen AS, et al. (2003b) Indirect enzyme-linked immunosorbent assay for the detection of antibody against Rift Valley Fever virus in domestic and wild ruminant sera. Onderstepoort J. Vet. Res. 70: 49–64.
[33]
Paweska JT, Mortimer E, Leman PA, Swanepoel R (2005) An inhibition enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in humans, domestic and wild ruminants. Journal of Virology Methods 127: 10–18. doi: 10.1016/j.jviromet.2005.02.008
[34]
Paweska JT, Jansen van Vuren P (2013) Rift Valley fever virus: a virus with potential for global emergence. In: Johnson N. The role of Animals in emerging viral diseases, editor. Elsevier, Academic Press. 169–200.
[35]
United Republic of Tanzania; The Animal Diseases Act No. 17 of 2003. Government Printer, Dar-es-Salaam.
[36]
Ministry of Health and Social Welfare United Republic of Tanzania (2011) The National Integrated Disease Surveillance and Response (IDSR) Guidelines, 2nd edition.
[37]
Mlozi MRS, Mtambo MMA (2008) Socio-economic impact analysis of the recent Rift Valley fever outbreak in Tanzania. FAO consultancy report.
[38]
Sindato C, Karimuribo E, Mboera LEG (2011) The epidemiology and socio-economic impact of rift valley fever epidemics in Tanzania: a review. Tanzania Journal of Health Research 13 (Suppl 1) DOI:http://dx.doi.org/10.4314/thrb.v13i5.1.
[39]
United republic of Tanzania; National sample census of agriculture, small holder agriculture volume III 2007/2008.
[40]
Food and Agriculture Organization; Livestock Information, sector analysis and policy branch, United Republic of Tanzania.
[41]
NBS (2002) United Republic of Tanzania, Population and Housing Census.
[42]
Morley CK (1999) Tectonic evolution of the East African Rift System and the modifying influence of magmatism: a review. Acta Vulcanologia 11: 1–19.
[43]
FAO (1988) FAO/UNESCO Soil Map of the World, Revised Legend with Corrections and Updates. World Soil Resources Report 60. Rome, Italy: FAO, Rome.
[44]
Kulldorff M, Heffernan R, Hartman J, Assun？ao RM, Mostashari F (2005) A space-time permutation scan statistic for the early detection of disease outbreaks. PLoS Medicine 2: 216–224. doi: 10.1371/journal.pmed.0020059
[45]
Anyamba A, Chretien JP, Small J, Tucker CJ, Formenty P, et al. (2009) Prediction of Rift Valley fever outbreak in the horn of Africa 2006–2007. Proceedings of the National Academy of Sciences of the United Staes of America USA 106: 955–959. doi: 10.1073/pnas.0806490106
[46]
Anyamba A, Linthicum KJ, Tucker CJ (2001) Climate-disease connections: Rift Valley fever in Kenya. Cadernos de Saude Publica 17: 133–140. doi: 10.1590/s0102-311x2001000700022
[47]
Nguku PM, Sharif SK, Mutonga D, Amwayi S, Omolo J, et al. (2010) An Investigation of a Major Outbreak of Rift Valley Fever in Kenya: 2006–2007. Am. J. Trop. Med. Hyg. (Suppl 2): 5–13. doi:–10.4269/ajtmh.2010.09–0288.
[48]
Hightower A, Kinkade C, Nguku PM, Anyangu A, Mutonga D, et al. (2012) Relationship of Climate, Geography, and Geology to the Incidence of Rift Valley Fever in Kenya during the 2006–2007 Outbreak. Am. J. Trop. Med. Hyg. 86(2): 373–380 doi:–10.4269/ajtmh.2012.11–0450.
[49]
Murithi RM, Munyua P, Ithondeka PM, Macharia JM, Hightower A, et al. (2010) Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts. Epidemiology and Infectious Diseases 18: 1–9. doi: 10.1017/s0950268810001020
[50]
Munyua P, Murithi RM, Wainwright J, Githinji J, Hightower A, et al. (2010) Rift Valley Fever Outbreak in Livestock in Kenya, 2006–2007. Am J Trop Med Hyg 83: 58–64. doi: 10.4269/ajtmh.2010.09-0292
[51]
Hosmer DW, Lemeshow S (2002) Applied logistic regression. 2nd ed. New York: John Wiley & Sons.
[52]
Balk D, Deichmann U, Yetman G, Pozzi F, Hay S, et al. (2006) Determining global population distribution: methods, applications and data. Advances in parasitology 62: 119–156. doi: 10.1016/s0065-308x(05)62004-0
[53]
Chevalier V, Lancelot R, Thiongane Y, Sall B, Diaite A, et al. (2005) Rift Valley fever in small ruminants, senegal, 2003. Emerg Infect Dis 11: 1693–1700. doi: 10.3201/eid1111.050193
[54]
Pfeffer M, Dobler G (2010) Emergence of zoonotic arboviruses by animal trade and migration. Parasites and Vectors 3: 35. doi: 10.1186/1756-3305-3-35
[55]
Gubler DJ (2002) The global emergence/resurgence of arboviral diseases as public health problems. Archives of Medical Research 33: (4) 330–342.
[56]
LaBeaud AD, Muchiri EM, Ndzovu M, Mwanje MT, Muiruri S (2005) Interepidemic Rift Valley fever virus seropositivity, northeastern Kenya. Emerg Infect Dis 14: 1240–1246. doi: 10.3201/eid1408.080082
[57]
Mboera LE, Kitua AY (2001) Malaria epidemics in Tanzania: An overview. African Journal of Health Scinces 8: 17–23.
[58]
Pienaar NJ, Thompson PN (2013) Temporal and spatial history of Rift Valley fever in South Africa: 1950 to 2011. Onderstepoort Journal of Veterinary Research 80: (1), Art. #384. Available: http://dx.doi.org/10.4102/ojvr. v80i1.384. Accessed 9 September 2013.
[59]
Anderson EC, Rowe LW (1998) The prevalence of antibody to the viruses of bovine virus diarrhea, bovine herpes virus 1, Rift Valley fever, ephemeral fever and bluetongue and to Leptospira sp. in free-ranging wildlife in Zimbabwe. Epidemiol. Infect. 121: 441–449. doi: 10.1017/s0950268898001289
[60]
Evans A, Gakuya F, Paweska JT, Rostal M, Akoolo L, et al. (2008) Prevalence of antibodies against Rift Valley fever virus in Kenyan wildlife. Epidemiol. Infect. 136: 1261–1269 doi:10.1017/S0950268807009806).
[61]
Sindato C, Swai ES, Karimuribo ED, Dautu G, Pfeiffer DU, et al. (2013) Spatial distribution of non-clinical Rift Valley fever viral activity in domestic and wild ruminants in northern Tanzania. Tanzania Veterinary Journal (Special) 28: 21–38.
[62]
Turell MJ, Rossi CA (1991) Potential for mosquito transmission of attenuated strains of Rift Valley fever virus. Am J Trop Med Hyg 44: 278–282.
