High Seroprevalence for Spotted Fever Group Rickettsiae, Is Associated with Higher Temperatures and Rural Environment in Mbeya Region, Southwestern Tanzania

Abstract

BackgroundRickettsioses are endemic in sub-Sahara Africa. Burden of disease, risk factors and transmission are hitherto sparsely described.MethodsFrom the EMINI (Evaluating and Monitoring the Impact of New Interventions) population cohort, we randomly selected 1,228 persons above the age of 5 years from the nine participating communities in Mbeya region, Southwestern Tanzania, stratified by age, altitude of residence and ownership of domestic mammals, to conduct a cross-sectional seroprevalence study in. The aim was to estimate the seroprevalence of IgG antibodies against Spotted Fever Group (SFG) rickettsiae and to assess socioeconomic and environmental risk factors. Serology (indirect immunofluorescence) was performed at a dilution of 1:64.ResultsSFG-seropositivity in the cohort was found to be 67.9% (range among nine sites: 42.8–91.4%). Multivariable analysis revealed an association with age (prevalence ratio, PR per 10 years: 1.08; 95% CI 1.06–1.10), warmer temperatures (PR per °C: 1.38; 1.11–1.71), male gender (PR 1.08; 1.00–1.16), and low population density (PR per 1.000 persons/km²increase 0.96; 0.94–0.99). At higher elevations, higher cattle density was associated with higher seroprevalence.ConclusionSFG rickettsial infection seems to be common in the more rural population of Mbeya Region. Spread seems to be further limited by temperature and higher elevation. Examination of the contribution of SFG to febrile illnesses seems warranted in a prospective study to estimate the disease burden in the population. This will also allow determination of the causative pathogens.

Seroprevalence of Alphavirus Antibodies in a Cross-Sectional Study in Southwestern Tanzania Suggests Endemic Circulation of Chikungunya

“…Together with previous reports on RVFV, rickettsiae of the typhus group and spotted fever group, we are demonstrating comparably high seroprevalences which could be caused by considerable exposure of the population to arthropod-borne infections other than malaria [23], [26], [27]. Akin to RVFV, a near-linear correlation of anti- Alphavirus IgG prevalence with age suggests endemic exposure rather than single or few epidemic events.…”

“…Rural living conditions, defined by low population density and long distances to roads, was a risk factor in our analysis of SFG rickettsia IgG [27]. Others authors also found this to be a risk factor for anti- Alphavirus IgG [33], so it is possible that rural conditions are the factor which increases the risk for both of these diseases which do not have much else in common.…”

Rickettsial seropositivity in the indigenous community and animal farm workers, and vector surveillance in Peninsular Malaysia

“…7 The indigenous community in Malaysia (also referred as Orang Asli or ‘original people') constitutes a minority group (0.6%) of the total population in Malaysia. 8 They stay in huts or settlements that are surrounded by primary or secondary forest, and engage in activities involving agriculture, hunting and collection of forest products.…”

“…People who live at the fringe of the forest or rural areas, including the indigenous community and animal farm workers, are regarded as populations who are at high risk of acquiring rickettsioses. 7 The indigenous community in Malaysia (also referred as Orang Asli or ‘original people') constitutes a minority group (0.6%) of the total population in Malaysia. 8 They stay in huts or settlements that are surrounded by primary or secondary forest, and engage in activities involving agriculture, hunting and collection of forest products.…”

Health Beliefs and Patient Perspectives of Febrile Illness in Kilombero, Tanzania

“…[1][2][3][4][5][6][7][8] Recent etiologic investigations of febrile illness in Tanzania have detected the prevalence of a variety of pathogens, including zoonoses, such as leptospirosis, brucellosis, salmonellosis, and Q-fever, and vector-borne pathogens, such as dengue virus, chikungunya virus, and Rift Valley fever virus. [9][10][11][12][13][14][15][16][17][18] In Tanzania's Morogoro region, diseases such as acute respiratory infections (ARIs), urinary tract infections, and typhoid fever have also recently been reported. [19][20][21] These agents may contribute to high morbidity and mortality in humans, and therefore, awareness of such acute febrile illness (AFI)-associated agents should be more fully evaluated among at-risk communities.…”