A Case of Hyper-reactive Malarial Splenomegaly. The Role of Rapid Antigen-detecting and PCR-based Tests

Tropical splenomegaly in a migrant-in-transit crossing the Darien gap, Panamá: A probable case of hyper-reactive malarial splenomegaly

Hyper-reactive malarial splenomegaly (HMS), or tropical splenomegaly syndrome, is a severe complication of chronic and recurrent infections caused by Plasmodium spp. This condition typically results in splenomegaly greater than or equal to 10 cm and a constellation of laboratory findings, including the absence of identifiable parasites in peripheral blood smears. However, patients with HMS demonstrate serological or molecular evidence of infection. Despite being a familiar entity in malaria holoendemic countries in Africa, and regions of Papua New Guinea, the pathophysiology, natural history, and treatment of the syndrome remains to be fully elucidated. Herein, we describe a highly suggestive case of HMS in a Senegalese patient migrating northbound to reach the U.S.-Mexico border and for whom we provided medical care during his crossing of the Darien Gap in Panama. We also reviewed the literature on diagnosing and treating HMS in-depth.

Case Report: Hyperreactive Malarial Splenomegaly Syndrome Diagnosed with Loop-Mediated Isothermal Amplification and Treated with Artemisinin-Based Combination Therapy

Hyperreactive malarial splenomegaly syndrome (HMSS) is a rare cause of splenomegaly in the Western world. Hyperreactive malarial splenomegaly syndrome is caused by an aberrant immunological response to chronic malaria exposure in endemic areas. Revised Fakunle's criteria may be helpful for diagnosis: persistent splenomegaly (> 10 cm below the costal margin), increased anti-Plasmodium antibodies, increased IgM levels, exclusion of other causes of splenomegaly or malignancy, and a favorable response to antimalarial treatment. We describe the case of a 16-year-old patient, who recently arrived in Belgium from Guinea with a history of splenomegaly and B symptoms in whom HMSS diagnosis was achieved, thanks to the loop-mediated isothermal amplification method. To our knowledge, this is also the first described case treated by dihydroartemisinin/piperaquine.

[Hyper-reactive malarial splenomegaly]

Hyper-reactive malarial splenomegaly is a rare and severe form of chronic malaria. This condition is a common cause of splenomegaly in endemic areas. The pathophysiology of hyper-reactive malarial splenomegaly involves an intense immune reaction (predominantly B cell-driven) to repeated/chronic infections with Plasmodium sp. The diagnosis may be difficult, due to a poorly specific clinical presentation (splenomegaly, fatigue, cytopenias), a long delay between residence in a malaria-endemic area and onset of symptoms, and a frequent absence of parasites on conventional thin and thick blood smears. A strongly contributive laboratory parameter is the presence of high levels of total immunoglobulin M. When the diagnostic of hyper-reactive malarial splenomegaly is considered, search for anti-Plasmodium antibodies and Plasmodium nucleic acids (genus and species) by PCR is useful. Diagnosis of hyper-reactive malarial splenomegaly relies on the simultaneous presence of epidemiological, clinical, biological and follow-up findings. Regression of both splenomegaly and hypersplenism following antimalarial therapy allows the differential diagnosis with splenic lymphoma, a common complication of hyper-reactive malarial splenomegaly. Although rare in Western countries, hyper-reactive malarial splenomegaly deserves increased medical awareness to reduce the incidence of incorrect diagnosis, to prevent progression to splenic lymphoma and to avoid splenectomy.

The hyper-reactive malarial splenomegaly: a systematic review of the literature

BACKGROUND

The hyper-reactive malarial splenomegaly syndrome (HMS) is a leading cause of massive splenomegaly in malaria-endemic countries. HMS is caused by a chronic antigenic stimulation derived from the malaria parasite. Classic Fakunle's major criteria for case definition are: persistent gross splenomegaly, elevated anti-malarial antibodies, IgM titre >2 SD above the local mean value and favourable response to long-term malaria prophylaxis. The syndrome is fatal if left untreated. The aim of this study is to systematically review the literature about HMS, particularly focussing on case definition, epidemiology and management.

METHODS

The search strategy was based on the following database sources: Pubmed, EmBase, Scopus. Search was done in March, 2014 and limited to English, Spanish, Italian, French, and Portuguese.

RESULTS

Papers detected were 149, of which 89 were included. Splenomegaly was variably defined and the criterion of increased IgM was not always respected. The highest prevalence was reported in Papua New Guinea (up to 80%). In different African countries, 31 to 76% of all splenomegalies were caused by HMS. Fatality rate reached 36% in three years. The most frequent anti-malarial treatments administered were weekly chloroquine or daily proguanil from a minimum of one month to lifelong. In non-endemic countries, a few authors opted for a single, short anti-malarial treatment. All treated patients with no further exposure improved. Cases not completely fulfilling Fakunle's criteria and therefore untreated, subsequently evolved into HMS. It seems thus appropriate to treat incomplete or 'early' HMS, too.

CONCLUSIONS

For patients not re-exposed to endemic areas, a short course of treatment is sufficient, showing that eradicating the infection is sufficient to cure HMS. Longer (probably lifelong) courses, or intermittent treatments, are required for those who remain exposed. Splenectomy, associated with high mortality, should be strictly limited to cases not responding to medical treatment.

Treatment of suspected hyper-reactive malarial splenomegaly (HMS) in pregnancy with mefloquine

Malaria infections in pregnancy are associated with adverse outcomes for both mother and child. There are few data on hyper-reactive malarial splenomegaly, an aberrant immunological response to chronic or recurrent malaria in pregnancy. This retrospective assessment reviewed the impact of mefloquine treatment on pregnant women with suspected hyper-reactive malarial splenomegaly in an area of low malaria transmission in the 1990s, showing significant reductions in spleen size and anemia and anti-malarial antibody titers without any notable negative effect on treated women or their newborns.

HMS-related hemolysis after acute attacks of Plasmodium vivax malaria

Among a cohort of 1,213 cases treated for Plasmodium vivax malaria from an isolated Papua New Guinean population, seven adults with severe and sustained hemolytic anemia after clearance of the peripheral parasitemia were prospectively investigated. All the patients fulfilled the criteria for hyper-reactive malarial splenomegaly and in 2 of 7 cases an IgG warm antibody was identified. Hereditary hemolytic anemia was excluded in 5 of 5 patients. All treated cases improved after an initial high dose of prednisone and antimalarial chemoprophylaxis. The persistence of marked anemia in a patient with splenomegaly after a P. vivax attack should raise the suspicion of hyper-reactive malarial splenomegaly.

Validation of PCR for detection and characterization of parasitaemia in massive splenomegaly attributed clinically to malaria infection

In this study, 101 patients with massive splenomegaly (MS) and 41 with moderate splenomegaly (MoS) from Kassala, Eastern Sudan, were included. The patients were recruited during a peak and the end of a malaria season and during a dry season between 2007 and 2008. Based on clinical findings and exclusion of other causes of MS, the former patients were presumed to be infected with malaria parasite; thus, the condition was termed as massive malarial splenomegaly (MMS). Rapid diagnostic test (RDT) and polymerase chain reaction (PCR) were used for malaria parasite detection. In the MMS group, the parasite rate was 50% and 49% as estimated by microscopy and RDT, respectively. However, the PCR showed higher parasite rate (79.3%, P = 0.000), Plasmodium vivax infection, and mixed infections. The PCR-corrected parasite rate in the MoS and control groups was 73.2% and 3.5%, respectively. The parasite rate as estimated by microscopy was highest at the end of the malaria season and lowest in the dry season; however, the parasite rate estimated by PCR was stable in all study periods. There was significant reduction in spleen size following anti-malaria treatment. In conclusion, the use of PCR had revealed significantly higher parasite rate, P. vivax, and mixed infections in MMS as compared to microscopy, while the RDT was found to be comparable to microscopy and is suggested to complement the use of the latter. The study also disclosed a seasonal variation of patent parasitemia with an overall low parasite count and scarce gametocytaemia in MMS.

The 'non-falciparum' malarias: the roles of epidemiology, parasite biology, clinical syndromes, complications and diagnostic rigour in guiding therapeutic strategies

Plasmodium vivax, P. ovale, P. malariae and P. falciparum routinely infect humans. The infections caused by these parasites are loosely referred to as vivax (or benign tertian), ovale, malariae (or quartan) and falciparum (or malignant tertian) malaria, respectively. Recently, P. knowlesi, a parasite of macaque monkeys in South-east Asia, has been identified as the cause of uncomplicated and severe human malaria in Malaysian Borneo. The prescription of appropriate therapies for reliably diagnosed malaria requires a grasp of the epidemiology of the 'non-falciparum' malarias, the biology of the parasites involved, the chemotherapeutic strategies that are available and the problems of emerging drug resistance and changing clinical syndromes. This review is intended to increase clinicians' understanding of how these factors relate to the selection of the antimalarial drugs to be given to a case of 'non-falciparum' malaria, with the aims of improving outcomes and preventing relapses and recrudescences.

Retention of erythrocytes in the spleen: a double-edged process in human malaria

PURPOSE OF REVIEW

Splenomegaly is frequent in acute or chronic forms of Plasmodium falciparum malaria, and splenectomy is associated with more frequent fever and parasitaemia. A novel role for the spleen in malaria is indicated by recent epidemiological and experimental data, bringing about a novel paradigm on severe malaria pathogenesis.

RECENT FINDINGS

In Sudanese children, severe malarial anaemia was associated with larger spleen, longer fever duration, and lower parasitaemia than cerebral malaria. These findings are consistent with evolution toward severe malarial anaemia being linked to the presence of a spleen-dependent mechanism that is absent or inefficient in cerebral malaria. An isolated-perfused human spleen model revealed unexpected retention of numerous erythrocytes harbouring young parasite stages (rings), probably through an innate mechanical process.

SUMMARY

A new paradigm is discussed, whereby the extent of erythrocyte retention in the spleen conditions not only haemoglobin concentration and spleen size but also the rate of parasite load increase. The prediction is that, in nonimmune children, stringent splenic retention of rings and uninfected erythrocytes reduces the risk of cerebral malaria (a complication associated with high parasite loads) but increases the risk of severe malarial anaemia. This hypothesis casts new light on epidemiological, genetic, and experimental studies in malaria pathogenesis.