Thrombotic Microangiopathy and the Kidney

Thrombotic microangiopathy can manifest in a diverse range of diseases and is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ injury, including AKI. It can be associated with significant morbidity and mortality, but a systematic approach to investigation and prompt initiation of supportive management and, in some cases, effective specific treatment can result in good outcomes. This review considers the classification, pathology, epidemiology, characteristics, and pathogenesis of the thrombotic microangiopathies, and outlines a pragmatic approach to diagnosis and management.

Drug-induced immune thrombocytopenia: incidence, clinical features, laboratory testing, and pathogenic mechanisms

Drug-induced immune thrombocytopenia (DIIT) is a relatively uncommon adverse reaction caused by drug-dependent antibodies (DDAbs) that react with platelet membrane glycoproteins only when the implicated drug is present. Although more than 100 drugs have been associated with causing DIIT, recent reviews of available data show that carbamazepine, eptifibatide, ibuprofen, quinidine, quinine, oxaliplatin, rifampin, sulfamethoxazole, trimethoprim, and vancomycin are probably the most frequently implicated. Patients with DIIT typically present with petechiae, bruising, and epistaxis caused by an acute, severe drop in platelet count (often to <20,000 platelets/pL). Diagnosis of DIIT is complicated by its similarity to other non-drug-induced immune thrombocytopenias, including autoimmune thrombocytopenia, posttransfusion purpura, and platelet transfusion refractoriness, and must be differentiated by temporal association of exposure to a candidate drug with an acute, severe drop in platelet count. Treatment consists of immediate withdrawal of the implicated drug. Criteria for strong evidence of DIIT include (1) exposure to candidate drug-preceded thrombocytopenia; (2) sustained normal platelet levels after discontinuing candidate drug; (3) candidate drug was only drug used before onset of thrombocytopenia or other drugs were continued or reintroduced after resolution of thrombocytopenia, and other causes for thrombocytopenia were excluded; and (4) reexposure to the candidate drug resulted in recurrent thrombocytopenia. Flow cytometry testing for DDAbs can be useful in confirmation of a clinical diagnosis, and monoclonal antibody enzyme-linked immunosorbent assay testing can be used to determine the platelet glycoprotein target(s), usually GPIIb/IIIa or GPIb/IX/V, but testing is not widely available. Several pathogenic mechanisms for DIIT have been proposed, including hapten, autoantibody, neoepitope, drug-specific, and quinine-type drug mechanisms. A recent proposal suggests weakly reactive platelet autoantibodies that develop greatly increased affinity for platelet glycoprotein epitopes through bridging interactions facilitated by the drug is a possible mechanism for the formation and reactivity of quinine- type drug antibodies.

Thrombocytopenic purpura after measles-mumps-rubella vaccination: a systematic review of the literature and guidance for management

OBJECTIVE

To determine the incidence of immune thrombocytopenic purpura (ITP) after measles-mumps-rubella (MMR) immunization compared with natural measles and rubella, its clinical course and outcome, and the risk of recurrence after repeat MMR vaccination.

STUDY DESIGN

We performed a systematic review of the Ovid MEDLINE (1950 to present) bibliographic database. We selected studies that reported cases of thrombocytopenia in a known number of children who were immunized with MMR vaccine before development of ITP. We also extracted data from the same and other studies regarding bleeding manifestations and the resolution of MMR-associated thrombocytopenia or thrombocytopenic purpura within 6 months. Finally, we studied the risk of ITP recurrence after MMR immunization or reimmunization.

RESULTS

On the basis of 12 studies, the incidence of MMR-associated ITP ranged from 0.087 to 4 (median 2.6) cases per 100,000 vaccine doses. Severe bleeding manifestations were rare, and MMR-associated thrombocytopenia resolved within 6 months from diagnosis in 93% of the children. MMR vaccination of unimmunized patients with ITP and revaccination of patients with prior ITP did not lead to recurrence of thrombocytopenia.

CONCLUSIONS

MMR-associated ITP is rare, self-limited, and non-life threatening, and susceptible children with ITP should be immunized with MMR at the recommended ages.

Immune thrombocytopenic purpura among the children attending at two teaching hospitals

The presenting features, diagnostic evaluation, seasonal variation and management performed in 110 children with immune thrombocytopenic purpura (ITP) attending at two tertiary level hospitals were evaluated. A peak incidence of children with ITP was observed during the month of June, July and the first step was found in May and lowest in the month of October to December. Mean initial platelet count was 65.5 x 10(9)/L. 35 patients with ITP did not require any treatment who were kept under observation and the rest 75 children who were admitted to hospital given platelet count enhancing treatment- intravenous immunoglobulin in 9, corticosteroids in 60 or both in 6 children with ITP. Intracranial hemorrhages were noticed in two children with ITP. So, this study suggests that ITP had special predilection during summer season and the least in winter along with variable approaches to management of these children.

Clinical surveillance of thrombotic microangiopathies in Scotland, 2003-2005

The prevalence, incidence and outcomes of haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are not well established in adults or children from prospective studies. We sought to identify both outcomes and current management strategies using prospective, national surveillance of HUS and TTP, from 2003 to 2005 inclusive. We also investigated the links between these disorders and factors implicated in the aetiology of HUS and TTP including infections, chemotherapy, and immunosuppression. Most cases of HUS were caused by verocytotoxin-producing Escherichia coli (VTEC), of which serotype O157 predominated, although other serotypes were identified. The list of predisposing factors for TTP was more varied although use of immunosuppressive agents and severe sepsis, were the most frequent precipitants. The study demonstrates that while differentiating between HUS and TTP is sometimes difficult, in most cases the two syndromes have quite different predisposing factors and clinical parameters, enabling clinical and epidemiological profiling for these disorders.

Is factor V Leiden a risk factor for thrombotic microangiopathies without severe ADAMTS 13 deficiency?

About 60% of patients diagnosed with acute thrombotic thrombocytopenic purpura (TTP) display a severe ADAMTS13 deficiency. Recently, Raife et al. concluded from a small case series, that factor V Leiden (FVL) might constitute a risk factor for acute thrombotic microangiopathy (TMA) without severe ADAMTS13 deficiency. Therefore, we determined ADAMTS13 activity and FVL carrier-ship in 256 consecutive patients presenting with various forms of acute TMA, including patients diagnosed with TTP or hemolytic-uremic syndrome (HUS). The overall prevalence of FVL was 8.2% (6.25% among patients diagnosed with TTP, and 9% among those with HUS) concordant with the FVL prevalence reported in Europe. FVL was present in 9.9% of patients with ADAMTS 13 activity < 10% and in 9.7% of those with normal ADAMTS13 activity (> 50%). We conclude that FVL is not more prevalent in TMA patients without as compared to those with severe ADAMTS13 deficiency. The prevalence of FVL carriers in certain HUS subgroups (HUS with ADAMTS 13 activity > 50%) reaching 12.3% suggests that a contributory role of FVL in the pathogenesis of defined forms of HUS needs further study.

The natural history of maternal immunization against foetal platelet alloantigens

Foetomaternal alloimmune thrombocytopenia (FMAIT) occurs when maternal antibodies of an antigen-negative mother cause destruction of sensitized foetal platelets. In Caucasian populations, 6-12% of human platelet antigen (HPA)-1a-negative women develop anti-HPA-1a, and the incidence of clinically affected cases is estimated to be 10-20% of immunized women. This study was performed in order to elucidate the rate of maternal immunization, incidence of FMAIT and the likely outcome of the condition in Asians. Excluding two or more pregnancies during the period, serum samples from 24 630 pregnant women, mainly Japanese, were screened for antibodies against platelet alloantigens by means of mixed passive haemagglutination (MPHA) (Anti-HPA-MPHA, Olympus, Tokyo). Antibodies were detected in 0.91% (223/24 630) of the women's samples and the immunization rate was correlated with the number of pregnancies. Antibody specificity included anti-HPA-4b (49), anti-HPA-5a (three), anti-HPA-5b (168), anti-HPA-4b + 5b (one) and anti-Nak(a) (CD36) (two). No alloimmunization was observed within the HPA-1, HPA-2, HPA-3 or HPA-6 systems. Among HPA-4b- or HPA-5b-negative women, 24% or 14% estimated, respectively, had antibodies and 26% (10/38) or 10% (12/125) of neonates, respectively, born to these mothers developed thrombocytopenia. Two neonates born to mothers having anti-HPA-4b developed generalized purpura. No cases of intracranial bleeding or death due to FMAIT were recorded. Generalized purpura due to FMAIT occurs in one in 9359 (95% CI: 1 in 77 519-1 in 2591) pregnancies solely because of HPA-4b incompatibility.

Clinical features and treatment outcomes of 79 infants with immune thrombocytopenic purpura

BACKGROUND

To determine the clinical features and treatment outcomes of infants with immune thrombocytopenic purpura (ITP).

METHODS

Retrospective analysis of 79 infant ITP patients treated from 1987 to 2002. The data abstracted comprised age, gender, clinical features, and treatment outcomes. A score test for the trend in the odds ratios was used to determine the risk of chronic ITP with advancing age. The infants were compared to a group of contemporaneous older children with regard to bleeding severity and incidence of chronic ITP.

RESULTS

The 34 female and 45 male infants had a median age of 16 months. Seventy-four presented with purpura, four with viral illnesses, and one was asymptomatic. Eight percent had active mucosal bleeding. The median platelet count was 8,000/microl. Forty infants received intravenous immunoglobulin, nine intravenous anti-D immunoglobulin, six steroids, and seven were observed without treatment. Fifty-five (76%) responded to a single course of treatment. Only 9% of infants developed chronic ITP compared to 18% of children between the ages of 25 and 119 months and 47% of children 120 months or older (P<0.0005).

CONCLUSIONS

Infants with ITP respond favorably to treatment and are less likely to develop chronic ITP compared to older children.

[Secondary effects of vaccinations]

The adverse effects of vaccines include local reactions and systemic symptoms or illnesses. Local reactions are frequent, most often presenting as transient pain, redness, edema and/or nodule. Fever of short duration is the main systemic symptom, generally occurring within 24-48 hours following vaccination. Some vaccines have recognized specific adverse effects such as thrombocytopenic purpura for the measles-mumps-rubella vaccine, and febrile convulsions for the pertussis vaccine. Hepatitis B vaccine and Haemophilus influenzae type b vaccine have been respectively suspected to be responsible for neurological demyelinating disease and insulin-dependent diabetes mellitus, but large-scale epidemiological studies have failed to confirm these allegations.

Acquired amegakaryocytic thrombocytopenic purpura (AATP): a hospital based study

OBJECTIVE

To determine the frequency of Acquired Amegakaryocytic Thrombocytopenic Purpura (AATT), possible aetiology, course and prognosis.

DESIGN

Retrospectively diagnosed patients, treated and followed prospectively.

SETTING

Department of Haematology, Armed Forces Institute of Pathology, Rawalpindi.

SUBJECTS

One hundred twenty patients with thrombocytopenic purpura.

MAIN OUTCOME MEASURES

Response to treatment and course of disease.

RESULTS

Out of 22 patients 2 died of cerebral haemorrhage, one transformed to Myelodysplastic Syndrome (MDS), one transformed to Acute Myeloid Levkaenia (AML). None is transfusion independent.

CONCLUSION

AATT is not an infrequent disorder. It shows poor response to all available therapeutic modalities and has a potential for transformation into Myelodysplasia and acute myeloid leukaemia.

Thrombotic thrombocytopenic purpura: understanding a disease no longer rare

Serial studies of plasma samples from patients during episodes of thrombotic thrombocytopenic purpura (TTP) have often shown either the presence of unusually large (UL) von Willebrand factor (vWf) multimers or, alternatively, absence of the largest plasma vWf forms. The presence of ULvWf multimers in TTP patient plasma may reflect impaired processing of the ULvWf forms released from endothelial cells. The disappearance of ULvWf and large vWf multimers in some TTP patient plasma samples during acute TTP episodes may be predominantly because these ULvWf forms, along with the largest vWf multimers, bind to platelets and cause aggregation. Serial flow cytometry studies of EDTA-whole blood samples from patients with initial episode, intermittent, and chronic relapsing types of TTP confirm that vWf is the likely aggregating agent, perhaps in association with fluid shear stress. The amount of vWf bound to single platelets has been found to be significantly increased during TTP relapses relative to remission periods in patients with all types of TTP. A substance in normal platelet-poor plasma and the cryoprecipitate-depleted fraction of normal plasma (cryosupernatant) is capable in vitro of reversibly reducing the size of ULvWf multimeric forms released by endothelial cells into the somewhat smaller vWf multimers ordinarily in circulation. This activity has characteristics of a limited disulfide bond reductase. The process of ULvWf breakdown may be made irreversible by the tandem proteolysis, catalyzed by a vWf metalloproteinase, of partially reduced vWf multimers. Several patients with chronic relapsing TTP have decreased or absent plasma vWf metalloproteinase activity, apparently on a congenital basis. Adult initial episode and intermittent TTP patients have been found to have vWf metalloproteinase activity inhibited by an autoantibody during, but not after, TTP epidsodes.

[Thrombocytopenic purpura after isolated or combined vaccination against measles, mumps and rubella]

A retrospective epidemiological survey was conducted to evaluate the incidence and characteristics of thrombocytopenic purpura (TP) reported in France following measles, mumps or rubella vaccination with monovalent or multivalent vaccines. Sixty cases of TP were reported i.e an incidence/100,000 doses of 0.23 and 0.17 for measles or rubella vaccines respectively given alone, to 0.87 for combined measles-rubella vaccine and 0.95 for MMR vaccine. The mean age was 21 +/- 12 months and the delay of diagnosis was 16 +/- 6 days after vaccination. Thrombopenia was severe (mean platelet count: 8000 +/- 6000/mm3) and always associated with purpura. The immediate outcome was favourable in 89.5 per cent of cases. Vaccine-associated TP appears to be similar to acute childhood idiopathic thrombocytopenic purpura but the clear temporal relationship between MMR vaccination and the occurrence of TP make a causal relationship highly plausible. Acute TP seems a rare complication of measles-rubella and MMR vaccination but clinicians had to be informed of the possibility of their occurrence. Acute TP following vaccination should be reported by physicians to their Regional Drug Surveillance Centre.

Chronic idiopathic thrombocytopenic purpura: incidence, treatment, and outcome

In order to determine incidence, outcome, trends in management and natural history, data on 92 children with chronic idiopathic thrombocytopenic purpura (ITP), comprising 66 from a single centre's experience between 1950 and 1980 and all 26 presenting from a defined population between 1984 and 1994, have been analysed. Its incidence, calculated from the population based group, is 0.46/10(5) children per year. Twenty nine of 34 (85%) remitted after splenectomy. Short initial histories predicted response to splenectomy. Splenectomy was offered only half as frequently in the last 10 years as in the 30 year, single centre group of children. Most (39 cases) of those not offered or successfully treated by splenectomy recovered spontaneously. The predicted spontaneous remission rate in 85 with adequate follow up data is 61% after 15 years. No other form of active treatment was of lasting benefit. No death solely attributable to chronic ITP occurred. The high spontaneous recovery rate, low mortality, and generally benign outcome may encourage a less interventionist approach to management.

Acute thrombocytopenic purpura following measles, mumps and rubella vaccination. A report on 23 patients

An acute thrombocytopenic purpura developed shortly after measles-mumps-rubella vaccination in 23 of approximately 700,000 children immunized over a period of seven years. The mean interval from inoculation to the onset of purpura was 19 days. Bone marrow aspirates obtained from 13 patients showed increased or normal amounts of megakaryocytes. Platelet survival time was markedly shortened in the two patients studied. Fifteen patients recovered (the platelet count exceeded 100 x 10(9)/l) in one month, five in two months and two in six months. Increase in platelet-associated immunoglobulin was detected in 10 of 15 patients. Circulating antiplatelet autoantibodies (AAb) against glycoprotein IIb/IIIa were detected in 5 of 15 patients. The findings are compatible with an autoimmune mechanism triggered by immune response to measles-mumps-rubella vaccination. As evaluated by the clinical course and the presence of AAb, post-vaccination thrombocytopenic purpura appears to be indistinguishable from childhood acute idiopathic thrombocytopenic purpura.

Alloimmunization to platelet antigen HPA-1a (PIA1) is strongly associated with both HLA-DRB3*0101 and HLA-DQB1*0201

Antibodies to the platelet HPA-1a antigen can elicit in the newborn a condition known as neonatal alloimmune thrombocytopenic purpura (NAITP). Previous studies based on RFLP analysis showed that 100% of HPA-1a-negative women who produced anti-HPA-1a antibodies (responders) were HLA-DRw52a (DRB3*0101). However, this specificity could also be found in some HPA-1a-negative women not producing anti-HPA-1a antibodies (nonresponders). We have analyzed in detail by PCR-SSOP the HLA-DR, -DQ, and -DP loci of 36 responders and 10 nonresponders. We found that while the allele DRB3*0101 was present in the vast majority of responders (91%), there were exceptions. Furthermore, the DQB1*0201 allele was found to be present in almost all responders (94%), but again was also found in nonresponders. The risk of alloimmunization to HPA-1a in an HPA-1b homozygous mother significantly increases with the presence of either allele, the odds ratio being 39.7 for DQB1*0201 and 24.9 for DRB3*0101. Sequencing of exon 2 of these two alleles from responders indicated no sequence difference when compared with the consensus sequences. This indicates that they do not represent variants when compared with the same alleles found in some nonresponders.

Onyalai

Onyalai is an acquired form of immune thrombocytopenia which differs clinically, epidemiologically and immunologically from idiopathic thrombocytopenic purpura (Table 4). The clinical hallmark is haemorrhagic bullae on the mucosa of the oronasopharynx. Haemorrhage from ruptured bullae, epistaxis or gastrointestinal bleeding is severe and may cause shock and death. The disease is limited to some black populations of central southern Africa, with a recorded incidence of one per 660 inhabitants per year in the Kavango territory of Namibia. The majority of patients demonstrate both IgG and IgM serum platelet antibodies and serum platelet glycoprotein IIb/IIIa autoantibodies. Chronic thrombocytopenia often ensues and recurrent episodes of clinical bleeding are common. Treatment directed at the prevention of haemorrhagic shock reduced the mortality rate in the acute phase from 9.8 to 2.8%. Standard dose prednisolone does not increase the platelet count. Vincristine sulphate may benefit some patients and splenectomy is indicated in patients with severe uncontrollable haemorrhage. High dose intravenous gammaglobulin may be followed by a rise in the platelet count and cessation of haemorrhage. The aetiology is unknown. The possible aetiological role of mycotoxins from contaminated millet, sorghum or maize requires further investigation.

Onyalai at Rundu, Namibia 1981-1988: age, sex, morbidity, mortality and seasonal variation of 612 hospitalized patients

Of 51,263 admissions to Rundu State Hospital in Namibia between 1981 and 1988, 612 (1.19%) were diagnosed as onyalai. The annual incidence varied between 0.96% and 1.66% of all admissions. The female to male ratio was 3:2. The mean age at presentation was 24.8 years (range 6 months to 80 years) and the mean hospital stay (and duration of clinical bleeding) for the years 1981 to 1982 and 1985 to 1988 was 7.68 d (range 1-38 d). Although the highest number of cases occurred during the months March, April and May a statistically significant monthly variation was not found. The treatment policy of commencing intravenous fluid on admission and a blood transfusion whenever the haemoglobin dropped below 10 g/dl in patients with active bleeding was associated with a mortality rate of 2.78% compared to 9.8% in cases recorded up to 1981.

Hemorrhagic sequelae of immune thrombocytopenic purpura in human immunodeficiency virus-infected hemophiliacs

Clinical bleeding tendency and tests of immune function were studied prospectively in 11 human immunodeficiency virus (HIV)-infected hemophiliacs with immune thrombocytopenic purpura (ITP) and a platelet count less than 50,000/microL. These 11 patients represented 13% of a well-characterized cohort of 87 HIV + hemophiliacs. ITP developed a mean 3.5 years after seroconversion, mean platelet count at presentation was 36,000/microL (range 15,000 to 49,000/microL), and the mean age at seroconversion was 37.1 years. Nine patients (82%) suffered bleeding complications, including four with intracranial hemorrhage, which was fatal in three. At the onset of ITP, five had AIDS and six were asymptomatic. Mean T4 lymphocyte count at onset of ITP was 126 +/- 32/microL (range 5 to 267/microL). Sustained treatment responses occurred with intravenous gammaglobulin (2 of 2), one of whom spontaneously remitted, and with zidovudine (1 of 2), but not with steroids (0 of 6) or danazol (0 of 3). In conclusion, 13% of a cohort of HIV + hemophiliacs has developed ITP with platelets less than 50,000/microL, a significant proportion of whom (82%) have experienced bleeding complications. It is recommended that treatment for ITP in HIV + hemophiliacs be instituted once the platelet count falls below 50,000/microL in order to avoid serious hemorrhagic sequelae.

Platelet surface-bound IgG and platelet-specific IgG in plasma in childhood thrombocytopenia

Quantification of platelet-bound immunoglobulin is widely used in the evaluation of thrombocytopenia. Several methods have been devised among which labelled ligand-binding assays seem to be most appropriate. In series of adult patients such assays have been shown to be superior in separating immune-thrombocytopenia from thrombocytopenia of non-immune causes. We studied 62 children with thrombocytopenia of various causes, using radiolabelled protein A as a ligand to measure platelet-surface bound IgG. The test was highly sensitive (93%) in detecting immune-thrombocytopenia. The specificity, however, was only 57%, which is less than in published studies of adults. In a number of cases presumed to be non-immune-thrombocytopenia, notably a few patients with leukaemia and bone marrow aplasia, we found increased amounts of platelet surface-bound IgG. The significance of this finding is not clear. An indirect assay measuring platelet-specific IgG in plasma was less sensitive (46%) but highly specific for immune-thrombocytopenia (89%). The measurements of platelet-surface-bound IgG and platelet-specific IgG in plasma are of limited diagnostic value in childhood thrombocytopenia but are useful in following the treatment in chronic ITP.

Childhood idiopathic thrombocytopenic purpura: report of 60 cases from Kuwait

Sixty children with idiopathic thrombocytopenic purpura (ITP) were admitted to a regional hospital in Kuwait over a 6-year period. A high annual incidence of ITP (12.5/10(5] was noted, probably related to viral infections during the period of the study. Forty-one were patients with acute ITP and 19 with chronic ITP. The initial treatment varied: corticosteroids were given in 33 cases, no therapy in 23 cases, and intravenous gamma globulin (IVGG) in four cases. Splenectomy was carried out in two children, of whom one died 2 years later as a result of septicaemia. This study showed that conservative management can be adopted in mild cases of ITP and active measurements should be reserved for patients presenting with moderate-severe mucocutaneous bleeding and significant thrombocytopenia.

Autoimmune thrombocytopenic purpura (AITP) in Zimbabwe

80 patients with autoimmune thrombocytopenic purpura (AITP) seen in Zimbabwe between January 1980 and December 1987 are presented. There was a female preponderance (male to female ratio of 1:1,9); and the mean age +/- s.d. was 18.1 +/- 14.5 (range 0.5 to 59) years. Seventy nine per cent of the acute AITP patients presented within the first decade of life; whilst 25% and 75% of the chronic AITP cases were seen below and above ten years respectively. Epistaxis was the commonest form of presentation; occurring in 70% of all cases. Platelet counts considered to be in the potentially dangerous level i.e. less than 40-50 X 10(9)/l were respectively found in 92% and 82% of the acute and chronic cases. The disease is not rare in Zimbabwe and presents with a picture identical with that previously described in Caucasian and other African populations.

Overview of ITP treatment modalities in children

Patients with idiopathic thrombocytopenia purpura (ITP) are frequently encountered by the pediatrician and pediatric hematologist. The clinical and laboratory features of ITP are quite uniform and facilitate prompt and accurate diagnosis. Bone marrow examination is not required in most cases since patients with alternative diagnoses (such as ALL) have greatly different presenting features. Acute ITP cannot be differentiated from the chronic form of the disease at presentation, nor can chronic disease be prevented by specific therapy administered for apparent acute ITP. Much controversy has revolved around whether an active interventionist (pharmacologic) or non-interventionist approach is preferred for management of ITP. The platelet count in both acute and chronic ITP often rises following treatment with prednisone and/or intravenous gamma globulin (IV GG), but such responses are transient and do not clearly provide protection against the rare complication of life-threatening hemorrhage. There are numerous disadvantages to an interventionist approach to therapy. Children with chronic ITP may require splenectomy if the disease is symptomatic enough to interfere with life-style, but the majority of these patients, too, require no specific therapy.

[A focus of thrombocytopenic purpura in East Azerbaidjan province, Iran (1974-1975) (author's transl)]

In Azerbaidjan, a rural province in the North-West of Iran, an hemorragic fever has been described, with a seasonal occurrence, mainly in July. it is characterized with the penia and thrombocytopenia. Its identification with the hemorragic fever of Crimea-Congo has been ruled out on clinical and biological arguments. In a new survey, fever appeared to be generally moderate or absent and the clinical aspect is that of a thrombocytopenic purpura. The role of a virus transmitted by tick, and a toxic etiology have been both suspected but not proved. Complementary surveys are necessary.

Childhood idiopathic thrombocytopenic purpura in Egypt and the neighboring Arab countries: a regional form with three different patterns of clinical expression

Childhood idiopathic thrombocytopenic purpura in the western world is essentially an acute self-limited disorder. In contrast, the clinical expression of the disease in Arab countries, as revealed by a study of 160 patients from Egypt, Saudi Arabia, Oatar and North Sudan, is heterogenous forming a spectrum that includes three distinct clinical forms: (a) the acute self-limited form, (b) the intermediate form, and (c) the chronic adulthood-like form. The relative proportions of these forms were 40. 15 and 45%, respectively. The chronic form shows limited response to steroids, and runs a platelet count less than 100,000 microliters for more than 1 year, with a tendency for later spontaneous elevation in platelet counts during the first few years of a long follow-up. The intermediate form shows a transient steroid-induced complete remission giving place to widely fluctuating platelet counts above and below 100,000 microliters once the steroid dosage is reduced to maintenance levels. Platelet counts in excess of 100,000 microliters were achieved in this group by extending steroid maintenance therapy fo 6--9 months. In spite of a tendency to chronicity and partial resistance to steroids i the intermediate and chronic forms, the overall response to steroids was enough both to reduce the number of cases requiring splenectomy to 15%, and to prevent the development of major complications in all the children included in the study.

[Idiopathic thrombopenic purpura in Algeria]

The study in Algeria over a period of 3 years of 90 cases of idiopathic thrombopenic purpura out of 409 hemorrhagic syndromes, showed the following peculiarities: the chronic forms are as frequent in the child as in the adult and we did not observe any subacute forms. Except in one case the use of prednisone at a dose of 2 mg/kg gave no result in patients who were not improved by a dose of 1 mg/kg.

[Clinical picture, pathophysiology and therapy of idiopathic thrombocytopenic purpura (author's transl)]

A review of the clinical picture, the therapy and the pathophysiology of idiopathic thrombocytopenic purpura (ITP) is presented. Emphasis is put on recent evidence concerning cellular and humoral autoimmune reactions, and their relevance for the pathogenesis of the disease is outlined.