title: Low folate status and indoor pollution are risk factors for endemic optic neuropathy in Tanzania.
abstract: OBJECTIVE
  Bilateral optic neuropathy in Dar-es-Salaam, Tanzania was first reported as an epidemic in 1988. Now argued to be endemic in 2010, the aetiology remains unclear. The authors investigated the hypothesis that low folate and vitamin B₁₂ status are associated with optic neuropathy, and also sought to investigate whether mercury, commonly used drugs, dietary factors and indoor pollution may also be risk factors.
  
  
  METHODS
  57 cases and 102 controls were recruited from two tertiary referral centres in Dar-es-Salaam. Data were collected on demographic characteristics, diet, medication history and HIV status. Folate and vitamin B₁₂ (holo-transcobalamin) were measured in stored serum samples. Exposure to mercury was assessed from concentrations in random urine samples.
  
  
  RESULTS
  Cooking indoors more than twice per week (OR 54.48 (95% CI 9.30 to 319.10)) and indoor use of charcoal or firewood (OR 21.20 (95% CI 2.51 to 179.36)) increased the risk of optic neuropathy. Risk was reduced in those with a higher folate status (highest versus lowest quartile OR=0.11 (95% CI 0.02 to 0.51)) and higher protein intakes (OR=0.84 (95% CI 0.72 to 0.96). No association was found with mercury exposure or any common drug or food commodity.
  
  
  CONCLUSIONS
  This study presents the first direct evidence of low folate status and indoor pollution in the aetiology of endemic bilateral optic neuropathy in Tanzania.
authors: Department of Nutrition & Public Health Intervention Research, London School of Hygiene & Tropical Medicine, London, UK.
authors: Katherine E
authors: KE
authors: Hodson
authors: Richard J
authors: RJ
authors: Bowman
authors: Milka
authors: M
authors: Mafwiri
authors: Mark
authors: M
authors: Wood
authors: Vincent
authors: V
authors: Mhoro
authors: Sharon E
authors: SE
authors: Cox
mesh_terms: D000293:Adolescent; D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects*; D002648:Child; D003296:Cooking; D004781:Environmental Exposure; D005492:Folic Acid / Q000097:blood*; D005494:Folic Acid Deficiency / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015596:Nutrition Assessment; D009901:Optic Nerve Diseases / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D013636:Tanzania / Q000453:epidemiology; D014792:Visual Acuity; D014805:Vitamin B 12 / Q000097:blood; D055815:Young Adult
chemical_list: D005492:Folic Acid; D014805:Vitamin B 12