Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Prevalence and Characteristics of Fluorosis Causing Skeletal Deformities in Rural Tanzania.

Jarvis2,  Helen G., Heslop2,  Peta S., Kissima1,  John, Walker3,  Richard

Hai District Hospital, Kilimanjaro Region, Tanzania, East Africa
Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
Northumbria Healthcare NHS Foundation Trust, Tyne & Wear, United Kingdom

Introduction:

Excessive ingestion of fluoride affects bone during growth causing a condition known as skeletal fluorosis (SF). This process can distort the congruence of joints, particularly weight bearing joints, leading to bone and joint pain. Previous small case series have reported rheumatological deformities in areas with high fluoride concentrations in the drinking water. Due to the harmful effects of excessive fluoride to teeth and bone the WHO (2004) recommended that fluoride levels in drinking water be < 1.5 mg/L. The area of Tanzania where the study was based had reported levels of fluoride as high as 35 mg/L in the ground water.

A survey was carried out to estimate the prevalence of SF in a Northern Tanzania village and the study was designed to focus on identifying those with deformity and disability due to SF.

Methods:

Using census information a door to door survey was conducted to identify cases of SF. Based on literature review and expert opinion, a diagnosis of severe SF was made if the following were identified on clinical examination: abnormal coronal tibio-femoral angle, sabre tibia or juvenile kyphosis/scoliosis with no alternative cause. Cases were then examined for other clinical manifestations, and disability/pain levels were estimated using a 4 point Likert scale. Social & educational exclusion were also assessed as part of the estimate of disease burden.

Results:

A population of 1435 were studied 762 (53%) Female & 673 (47%) Male, of whom 1135 (79%) were under 30 years of age. We identified 56 cases (22 (39%) female & 34 (61%) male) of severe SF (aged 2 – 30 yrs). This gives a crude prevalence of 3.9% of severe deforming disease.

52 (93%) had evidence of coronal tibio-femoral joint deformities - 45 valgus & 7 varus. Sabre tibia was identified in 18 (32%) and juvenile scoliosis/kyphosis in 3 (5%) of the cases. Combinations of the above diagnostic criteria were common with 2 cases having all 3 conditions.

Pain was reported in 37 (66%) cases using the ascending 4 point Likert severity scale. 25 (45%) reported moderate to severe pain & 36 (64%) reported limitation of normal activities. 97% had knee and lower limb pain with only 32% of those reporting pain in other skeletal sites.

17 (30%) felt their school attendance had been affected & 5 (9%) felt they were treated differently by their peers due to their SF.

Financial constraints meant only those with the worst deformities were referred for corrective surgery. 11 children have been operated on to date.

Conclusion:

In this area with very high levels of fluoride in the ground water, SF is a common condition. The prevalence of nearly 4% in this village represents only the most severe end of the spectrum, being an estimate of the disability and burden that this condition causes in a community ingesting excessive amounts of fluoride. It appears that only the under 30's in the population have been affected by severe SF, most likely due to the time of construction of the deep wells in the area, which carry higher fluoride levels than surface water. Severe SF also seems to be more common in males than females, possibly due to hormonal effects. The study group is currently investigating why, despite endemic exposure, only a minority appear to develop severe deforming disease.

To cite this abstract, please use the following information:
Jarvis, Helen G., Heslop, Peta S., Kissima, John, Walker, Richard; The Prevalence and Characteristics of Fluorosis Causing Skeletal Deformities in Rural Tanzania. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1568
DOI: 10.1002/art.29334

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