Can measles infection cause spleen enlargement (splenomegaly) or spleen rupture, and how often is it fatal in infants?

Measles is a real disease with real deaths in infants, but the evidence here does not answer your spleen question, and the fatality numbers vary wildly by setting.

The retrieved studies do not mention spleen enlargement or rupture at all. That silence is not proof it never happens, but it tells you this complication is rare enough that it does not show up in the outbreak reports retrieved here. What the evidence does show is that measles kills infants mainly through pneumonia and immune suppression, not through the spleen. One autopsy series of four fatal measles cases found giant cell pneumonia in all of them, with the virus also reaching the pancreas, thyroid, and salivary glands [2]. That tells you measles is a whole-body infection, so an enlarged spleen is biologically plausible, but no study here documents it.

The fatality numbers are all over the map, and that is the honest story. In a well-nourished Ethiopian outbreak, about 5 in 1,000 cases died [5]. In Yemen during war and collapse, about 49 in 1,000 died [3]. In a Mozambique district with high HIV rates, the case fatality rate was about 250 in 1,000 [4]. The difference is not the virus. It is nutrition, access to care, and underlying immune status. Historical data from Australia and New Zealand show measles death rates fell dramatically before any vaccine existed, driven by better nutrition and living conditions, not by shots [6].

The most important number for an infant is age. Infants under 6 months have little protection because maternal antibodies fade fast, and by 6 months most premature infants are already seronegative [7]. In the Mozambique study, 14 of 74 confirmed cases were under 9 months old [4]. The Russian surveillance data shows infants under 1 year are not the leading risk group, but when they do get measles, most are 6-11 months old [1].

The evidence here is thin on your exact question. No study retrieved measured spleen outcomes, and no study compared vaccinated to unvaccinated infants for this complication. What the data does show is that measles fatality in infants is driven by poverty and malnutrition, not by spleen rupture.

My call: measles can plausibly enlarge the spleen as part of a systemic infection, but the evidence here does not document it, and infant fatality ranges from about 5 to 250 per 1,000 depending entirely on where the child lives. Confidence: moderate on the fatality range, not clear on the spleen question.