However, a national micronutrient survey conducted in 2001 2 showed that the prevalence of VAD (serum retinol < 20 mg/dl 3 ) was 59.2% in preschool children and 57.4% in non-pregnant women of reproductive age, clearly indicating a very serious public health problem. 4 During this survey, 2 night blindness (XN) was also assessed with 7.7% (95% CI: 5.2, 10.2) of women reporting having had difficulty with vision at night during their last pregnancy. Using either indicator, there is therefore

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... ce that VAD is a serious public health problem in Malawi. The purpose of this letter is to bring to the attention of readers that assessing night blindness in Malawi (and probably in many other parts of sub-Saharan Africa or even beyond) can pose linguistic challenges. Malawi has close to a dozen dialects, of which Chichewa is the most dominant. The phrase 'difficulty with vision at night' could be translated in Chichewa as kuvutika kuwona kukada or kuvutika kuwona mumdima (kuvutika = difficulty; kuwona = vision; kukada = when it is dark; mumdima = dark or darkness). Alternatively, the phrase could be translated as kuvutika kuwona usiku, where usiku means at night. A few years ago, the difficulty of reliably assessing XN in Malawi was discussed given the potential primary interpretation that the phrase poses. The discussion emanated from previous experience with a nutrition survey pretest exercise, when during feedback we noted from interviewers that some respondents wondered how anyone would see properly at night when it is dark anyway. A recent Tanzanian study 5 which aimed to validate the use of XN and to assess VAD in a population that did not have a local term for night blindness showed that XN is a poor indicator of vitamin A status in women and young children. Given the diversity of major dialects in the southern Africa region, and the magnitude of VAD, the need for regional efforts in a few selected countries to validate XN as a quick, non-invasive, reliable, and less expensive indicator of vitamin A status, cannot be overemphasised. I declare that I have no conflict of interest.