A stepwise diagnostic approach for undiagnosed Anemia in children: A model for low-middle income country

BACKGROUND

Reaching a precise diagnosis in rare inherited anemia is extremely difficult and challenging, especially in areas with limited use of genetic studies, which makes undiagnosed anemia a unique clinical entity in tertiary hematology centers. In this study, we aim at plotting a stepwise diagnostic approach in children with undiagnosed anemia while identifying indications for genetic testing.

PATIENTS AND METHODS

A one-year cross-sectional study involved 44 children and adolescents with undiagnosed anemia after undergoing an initial routine panel of investigations. They were classified based on mean corpuscular volume (MCV) into 3 groups: microcytic (n = 19), normocytic (n = 14) and macrocytic (n = 11). An algorithm that included four levels of investigations was devised for each category.

RESULTS

After applying a systematic diagnostic approach, 33 patients (75 %) were diagnosed of whom 7 (15 %) had combined diagnoses, while 11 (25 %) patients remained undiagnosed. Based on the first, second, third and fourth levels of investigations, patients were diagnosed, respectively, as follows: of the 11 patients, 7 were microcytic, 3 normocytic and 1 macrocytic; of the 7 patients, 2 were microcytic, 2 normocytic, and 3 macrocytic; of 10 patients, 5 were microcytic, 4 normocytic and 1 macrocytic; finally, of the 16 patients, 8 were microcytic, 6 normocytic and 2 macrocytic. Numbers recorded appear higher than the actual number of the patients because some of them were diagnosed by more than one level of investigation. The diagnoses obtained in the microcytic group showed hemoglobinopathies, iron refractory iron deficiency anemia (IRIDA), membrane defects, sideroblastic anemia, hypo-transferrinemia, a combined diagnosis of sickle cell trait and pyropoikilocytosis. The diagnoses also showed a combined diagnosis of hereditary spherocytosis (HS) and alpha thalassemia minor, and a combined diagnosis of iron deficiency anemia and beta thalassemia minor, while 15 % remained undiagnosed. In the normocytic group, the diagnosis revealed autosomal recessive (AR) HS, vitamin B12 deficiency, pyruvate kinase deficiency (PKD), congenital dyserythropoietic anemia (CDA) type I, Diamond Blackfan anemia and beta thalassemia major. In addition, it showed a combined diagnosis of AR HS and CDA type II, a combined diagnosis of AR HS and PKD, and a combined diagnosis of dehydrated stomatocytosis (DHS) and G6PD carrier, meanwhile 20 % remained undiagnosed. Finally, the macrocytic group was diagnosed by vitamin B12 deficiency, sideroblastic anemia, PKD, a combined diagnosis of PKD and G6PD deficiency carrier, while 45 % remained undiagnosed.

CONCLUSION

Conducting a stepwise approach with different levels of investigations may help reach the diagnosis of difficult anemia without having to resort to unnecessary investigations. Combined diagnosis is an important cause of undiagnosed anemia, especially in countries with high frequency of consanguinity. The remaining 25 % of the patients continued to be undiagnosed, requiring more sophisticated investigations.

Prevalence of Cryptosporidium species isolated from diarrheic children in Makkah, Saudi Arabia

Cryptosporidiosis has been identified as a significant underlying cause of morbidity and mortality worldwide. Studies in high and low income countries have recognized the importance of Cryptosporidium as a cause of diarrhea. The objectives of the current study were to determine the prevalence rate and genotypes of Cryptosporidiumin in diarrheic children in Makkah Region. A total of 1,380 fecal samples were collected from children aged up to 14 years attending 3 major hospitals of Makkah between March 2015 and March 2016. Stool collected were subjected to direct microscopic examination and crypto antigen detection using ImmunoCard STAT, Cryptosporidium/Giardia rapid test. Part of each positive stool sample was kept frozen at -20ºC for molecular characterization. Initial screening by immunochromatographic detection kit revealed 23 positive cases. PCR was performed for positive cases by amplification of a piece of the gene encoding the small (18S) subunit of rRNA producing a 435-438 bp product. Cryptosporidium genotyping was performed by RFLP analysis of PCR products. Genotyping revealed 18 cases C. hominis genotype, 4 cases C. parvaum genotype and one sample failed to be amplified. The data revealed a higher incidence of the common human species C. hominis (81.8%). The detection of both C. hominis and C. parvaum genotypes point to the possibility of both anthroponotic and zoonotic transmission routes occurring in Makkah region. Further studies are needed to verify the subgenotypes of Cryptosporidium to elucidate the real transmission modes and hence plan for effective control strategies.

Sensitive and specific assay for detecting circulating antigens in individuals infected with Schistosoma mansoni

Monoclonal antibody 128C3/3/21 in an antigen-capture ELISA was used to detect circulating antigen in individuals infected with Schistosoma mansoni. This antibody recognizes a carbohydrate epitope expressed on the major group of acidic egg glycoproteins and on glycoproteins and glycolipids in all other stages of parasite development. The overall sensitivity of the assay was 78%, with a sensitivity of 100% for patients excreting >100 egg/g feces (EGF) and 72% for those excreting <100 EGF. By increasing the degree of antibody biotinylation, the authors have now achieved sensitivities of 92.4% overall and 82% for those excreting <100 EGF. A direct increase in the mean level of circulating antigen was found with increasing egg counts. The difference between those excreting >100 EGF (53 individuals) and those excreting <100 EGF (39 cases) was statistically significant (P<0.01). None of the control sera (23 uninfected individuals and 16 patients infected with other parasites) had circulating antigen levels >80 ng/ml. Thus, the test specificity was >99%. The test accuracy was 94.7%, the positive predictive value 100%, and the negative predictive value 84.8%.

Specific anti-Toxoplasma antibodies in relation to infection and reinfection using different infective stages

The possibility of rat re-infection with different Toxoplasma gondii stages was studied in this work. Two groups of rats were infected with either intra-peritoneal injection of 1000 trophozoites of virulent Toxoplasma strain or 1000 oocysts through oral routes. IgA, IgM and IgG were detected 15, 30, 60 and 120 days post infections. IgA and IgM appeared as early as 15 days post infection but declined afterwards. IgA antibody response was more prominent with oocyst infection and IgM was more prominent with tachyzoite infection with insignificant statistical difference. On the other hand, IgG started to increase 60 days post infection, then increased gradually till the end of the experiment (120 days). The primary orally infected rats were either re-infected orally with oocysts or intra-peritoneal trophozoites and re-examined after 15 and 120 days for the same immunological parameters. Those rats which primary infected with intra-peritoneal trophozoites were re-examined after oral infection with oocysts or injection of trophozoites intra-peritoneal. The level of IgA and IgM in one rat of group A and 2 rats of group B were significantly increased and this occurred in presence of anti-Toxoplasma IgG from the primary infection. In this study, the rats were lab-bred so, the factors affect the immune system could be under control, also strain variability was excluded as the infection was only by one strain, and as the IgG level was high, these rats were presumed to be immune from the primary infection. So, the rats which became positive after challenge most probably re-infected.

Circulating filarial antigens for monitoring the efficacy of ivermectin in treatment of filariasis

Seventy-three asymptomatic bancroftian filariasis patients with positive microfilaria in their blood films were included. The patients were randomly divided into 2 groups: ivermectin group (50 cases) given 2 doses each of 100 ug/kg body weight, 3 months apart, and 23 cases had 2 doses of placebo. The study was run blindly for one year. The initial mean microfilaria (MF) count was 111/ml. At 3 months after ivermectin therapy, mean MF became 7.8/ml and 24% of ivermectin treated cases had no detectable MF (P <0.05). At 6, 9 and 12 months, the mean MF count became 4.1, 6.5 and 11/ml with amicrofilaria in 54%, 42% and 40% of treated cases respectively (P <0.05). On the other hand, no statistically significant change in the mean MF count in placebo group was detected. The routine laboratory investigations were unchanged or slightly improved at 3 and 6 months. Side effects after the first dose of ivermectin were mild fever in 16% and weakness in 20%. None was recorded after the second dose. Circulating filarial antigens could be detected in 66% of cases before treatment, as all cases with high microfilaremia had positive antigenemia. The mean antigen level started to decline significantly after 9 months post treatment. At the end of the study (one-year), all negative microfilaremic cases had negative antigen levels, indicating that detection of antigen in-patients sera is a very good indicator of cure and efficacy of the drug.