Abstract
BackgroundThe hyperreactive malarial splenomegaly (HMS) represents a chronic, potentially fatal complication of malaria. Case definition includes: gross splenomegaly, high level of anti-malarial antibody and IgM, response to long-term anti-malarial prophylaxis. In this study, a large series of patients not fully meeting the case definition was tentatively classified as early hyperreactive malarial splenomegaly (e-HMS). The main research questions was: does “e-HMS” tend to evolve to the full-blown syndrome? And if so, what are the main factors influencing this evolution?MethodsRetrospective, longitudinal study. The patient database was searched to retrieve all potentially eligible patients. e-HMS was defined by splenomegaly of any size (with or without raised IgM), high anti-malarial antibody titre and exclusion of other causes of splenomegaly. The clinical outcome at following visits was analysed in relation to re-exposure to malaria, and to treatment (only part of the patients with e-HMS were treated with a single anti-malarial treatment and advised to follow an effective anti-malarial prophylaxis, if re-exposed). The association of the outcome with the main independent variables was first assessed with univariate analysis. A stepwise logistic regression model was then performed to study the association of the outcome with the main independent variables.ResultsOne hundred and twenty-six subjects with e-HMS were retrieved. Eighty-one had at least one follow-up visit. Of 46 re-exposed to malaria for a variable period, 21 (46 %) had progressed, including 10/46 (22 %) evolving to full-blown HMS, while of 29 patients not re-exposed, 24 (93 %) had improved or cured and five (7 %) progressed (p < 0.001). At logistic regression re-exposure was confirmed as a major risk factor of progression (OR 9.458, CI 1.767–50.616) while treatment at initial visit was protective (OR 0.187, CI 0.054–0.650).Conclusione-HMS should be regarded as a clinical condition predisposing to HMS. Although the case definition may include false positives, e-HMS should be treated just as the full-blown syndrome. A single anti-malarial treatment is probably adequate, followed by effective prophylaxis for patients exposed again to malaria transmission.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-1015-6) contains supplementary material, which is available to authorized users.
Highlights
The hyperreactive malarial splenomegaly (HMS) represents a chronic, potentially fatal complication of malaria
Laboratory methods for malaria detection Patients were screened for Plasmodium using one of the following methods: QBC Malaria Test (QBC Diagnostics Inc, Philipsburg, US) or Malaria antigen Rapid Detection Test (RDT)
Anti-malarial antibodies were available for 86/97 Caucasian patients and for 20/29 non-Caucasians, while in the other cases the inclusion was based on the alternative criteria of ≥3 years stay in malaria-endemic areas and ≥10 acute malaria episodes
Summary
The hyperreactive malarial splenomegaly (HMS) represents a chronic, potentially fatal complication of malaria. Case definition includes: gross splenomegaly, high level of anti-malarial antibody and IgM, response to longterm anti-malarial prophylaxis. A large series of patients not fully meeting the case definition was tentatively classified as early hyperreactive malarial splenomegaly (e-HMS). The hyperreactive malarial splenomegaly (HMS), previously referred to as tropical splenomegaly or tropical splenomegaly syndrome (TSS) is a chronic complication of malaria. Patients have high levels of anti-malarial antibody [1, 2], as a result of the chronic antigenic stimulation, which seems to be an important factor in the development of the syndrome. Especially pregnant women are susceptible to episodes of massive haemolysis, which are usually preceded by febrile episodes [10]
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