Severe Iron Deficiency Anemia and Lice Infestation

Background

Lice infestation is a commonly encountered disorder in emergency medicine. The louse survives from a blood meal from its host; hence, iron deficiency anemia is a theoretic possibility. A limited number of reports of severe iron deficiency anemia have appeared in the veterinary literature, but a thorough review of the medical literature did not reveal a single instance in human beings.

Objective

We report a small case series of patients with heavy louse infestation and profound iron deficiency anemia.

Case report

The index case along with two other cases discovered from an exhaustive search of 4 years of the institution’s Emergency Department records all had heavy infestation with head and body lice. Laboratory evaluation revealed serum hemoglobin levels under 6 gm/dL, low serum ferritin levels, and microcytic red blood cell indices. All patients were admitted to the hospital, received transfusions, and had evaluation of their anemia. No patient had evidence of gastrointestinal blood loss or alternative explanation for their anemia.

Conclusions

Although cause and effect cannot be established from this case series, to the best of our knowledge, this is the first published evidence of a provocative association of louse infestation and severe iron deficiency anemia in humans.     

An incurable itch: Head lice

Question Head lice infestations continue to be seen frequently in many communities. Some of these children require multiple treatments before eradication. What are the current treatment recommendations for head lice?Answer Head lice (Pediculus humanus capitis) infestations are common, particularly among school-aged children. In order to minimize louse resistance, insecticide usage, and social stigmatization, diagnosis and treatment should be limited to those with live lice on the scalp. Options for management are predominantly topical therapies or physical removal. Large studies comparing the efficacy of these treatments are lacking. Treatment should be repeated in approximately 7 days if topical insecticides are used or every 2 to 3 days for 2 weeks if wet combing is used. Lice resistance patterns vary widely geographically, and resistance is now the most common cause of treatment failure.Pediculosis (infestation with head lice, Pediculus humanus capitis) is the most common parasitic infection in children.¹ The highest prevalence is in children between 3 and 11 years old and in girls, with no relevant seasonal variation nor relation to level of hygiene.²The diagnosis of pediculosis requires the presence of live lice on the scalp, not only the presence of nits (hatched empty eggshells).³ Detection by combing was found to be 3.8 times more effective than visual inspection for live lice.⁴ The human head louse (Pediculus humanus capitis) is a parasite with 6 legs that cannot fly or jump; thus, lice are transmitted by head-to-head contact. As obligate human blood feeders, lice do not survive away from a human host for more than 3 days.¹ The role and extent of fomite transmission (eg, hats, hair accessories, bedding) remains controversial.²An adult louse deposits eggs close to the scalp and the eggs hatch within 6 to 9 days. Within 9 to 15 days these nymphs mature to adults and begin laying eggs.² The life span of a louse is generally 3 to 4 weeks and it can lay 50 to 150 eggs in this time frame.⁵The characteristic itch that is classic of head lice infestations is caused by irritation from saliva injected by the feeding louse. This might take 2 to 6 weeks to develop with the first infestation, and subsequent infestations might take hours for symptoms to start.⁶     

The life of a head louse

When children return to school after the summer holiday, cases of head lice appear to increase. Ian Burgess describes the life cycle of the head louse and dispels some of the myths about transmission of this insect. A second article discusses the detection and treatment of head lice.     

Head lice resistance: itching that just won't stop

OBJECTIVE: To evaluate the reports of resistance and cross-resistance to pediculicides in the head louse (Pediculus capitis), as well as the mechanisms involved. DATA SOURCES: Literature identified through a MEDLINE search (1966-April 2000) and through other secondary literature databases and/or bibliographies of pertinent articles. DATA SYNTHESIS: Head lice infestation is a common, worldwide problem. The widespread use of insecticide treatments together with inadequate treatment methods has led to a concern regarding the potential development of resistant head lice. This literature review examines the reports of resistance of the head louse as well as the purported mechanisms involved. CONCLUSIONS: Current research suggests that head lice resistance exists, but little is known regarding the actual incidence of this resistance or whether this incidence is increasing. More research is needed to assess the status of this problem. Proposed mechanisms for head lice resistance include knock-down resistance, glutathione S-transferase-based resistance, and monooxygenase-based resistance.     

Overcoming health inequalities by using the Bug Busting 'whole-school approach' to eradicate head lice

Aims and Objectives. The aim of this paper was to illustrate the socially inclusive nature of the Bug Busting ‘whole‐school approach’ to head louse eradication. Background. In the UK, Belgium and Denmark, persistent head lice in families of all socio‐economic status (SES) is a problem. Since 1995 in the UK and 1998 elsewhere, an educational programme intended to teach families how to detect and treat head lice by using the Bug Busting wet combing method has been organized in some areas. Local schools lead this community strategy for prevention, known as a ‘whole‐school approach’ (UK). Design and methods. We describe five studies applying the Bug Busting approach, four set in districts where some disadvantaged families live (UK and Belgium) and a fifth set in Denmark. Feasibility and consumer satisfaction are examined. One UK study analyses data on area prescribing for head lice and the impact in a deprived locality of raising the profile of Bug Busting. Results. We find parental education in Bug Busting enables families of all SES to participate in a ‘whole‐school approach’ to head lice. Best results are obtained when each family has a Bug Buster Kit. This provides all the combs necessary with full instructions on their use with ordinary shampoo and conditioner to detect lice, eradicate an infestation mechanically, or to check the success of any treatment. In the UK, the promotion of the Bug Busting approach is reducing primary care expenditure on treatment for head lice and professional time spent with worried parents. As a result, healthcare providers can give time to the few families who require one‐to‐one guidance. Relevance to Clinical Practice. Incorporation of the Bug Busting approach to head lice into clinical practice in school communities contributes to sustainable control whilst overcoming health inequalities in participating families.     

Transgene‐mediated suppression of the RNA interference pathway in Aedes aegypti interferes with gene silencing and enhances Sindbis virus and dengue virus type 2 replication

RNA interference (RNAi) is the major innate antiviral pathway in Aedes aegypti that responds to replicating arboviruses such as dengue virus (DENV) and Sindbis virus (SINV). On the one hand, the mosquito's RNAi machinery is capable of completely eliminating DENV2 from Ae. aegypti. On the other, transient silencing of key genes of the RNAi pathway increases replication of SINV and DENV2, allowing the viruses to temporally overcome dose‐dependent midgut infection and midgut escape barriers (MEB) more efficiently. Here we expressed Flock house virus B2 (FHV‐B2) from the poly‐ubiquitin (PUb) promoter in Ae. aegypti using the ΦC31 site‐directed recombination system to investigate the impact of transgene‐mediated RNAi pathway suppression on infections with SINV‐TR339eGFP and DENV2‐QR94, the latter of which has been shown to be confronted with a strong MEB in Ae. aegypti. FHV‐B2 was constitutively expressed in midguts of sugar‐ and blood‐fed mosquitoes of transgenic line PUbB2 P61. B2 over‐expression suppressed RNA silencing of carboxypeptidase A‐1 (AeCPA‐1) in midgut tissue of PUbB2 P61 mosquitoes. Following oral challenge with SINV‐TR339eGFP or DENV2‐QR94, mean titres in midguts of PUbB2 P61 females were significantly higher at 7 days post‐bloodmeal (pbm) than in those of nontransgenic control mosquitoes. At 14 days pbm, infection rates of carcasses were significantly increased in PubB2 P61 mosquitoes infected with SINV‐TR339eGFP. Following infection with DENV2‐QR94, midgut infection rates were significantly increased in the B2‐expressing mosquitoes at 14 days pbm. However, B2 expression in PUbB2 P61 did not increase the DENV2‐QR94 dissemination rate, indicating that the infection phenotype was not primarily controlled by RNAi.     

Home remedies to control head lice: assessment of home remedies to control the human head louse, Pediculus humanus capitis (Anoplura: Pediculidae)

As the frequency and level of pediculicide resistance increases throughout the world, the need for novel solutions to control pediculosis has intensified. The development and registration of new pesticides has become so costly that many chemical companies are unwilling to pursue it and health-care providers now face a serious lack of new commercial pediculicides. Many infested people resort to using "home-remedy" approaches that have not been scientifically tested. In this article, we examined the potential value of six purportedly effective "home remedies" (vinegar, isopropyl alcohol, olive oil, mayonnaise, melted butter, and petroleum jelly) to treat head louse infestations and the likelihood of drowning lice by water submersion. Results indicated that only the application of petroleum jelly caused significant louse mortality but no treatment prevented lice from laying eggs. Most home remedy products did little to kill eggs, despite prolonged exposure. Petroleum jelly caused the greatest egg mortality, allowing only 6% to hatch. It was extremely difficult to drown lice, despite extended periods (i.e., 8 hr) of water submersion, suggesting that killing lice by depriving them of oxygen is inefficient. None of the home remedy products we surveyed was an effective means of louse control. This suggests that when treatment failure occurs, an increased amount of time and effort should be focused on alternative chemical pediculicides and/or manual louse removal (i.e., combing) rather than using any of these products.     

Induction of partial immune tolerance to factor VIII through prior mucosal exposure to the factor VIII C2 domain

Summary. Background: The development of anti‐factor VIII (FVIII) neutralizing antibodies (inhibitors) is a significant obstacle to FVIII replacement therapy. Objective: As mucosal administration of an antigen may induce immune tolerance we have evaluated the efficacy of mucosal antigen exposure to achieve tolerance to FVIII. Methods: We investigated the effects of oral and nasal administration of the purified FVIII C2 domain (FVIII‐C2) to FVIII‐deficient BALB/c mice prior to FVIII protein challenge. Mice received oral or nasal doses of FVIII‐C2, followed by a subcutaneous challenge of either FVIII‐C2 or FVIII. The development of anti‐FVIII inhibitors, cytokine production by splenocytes in vitro, and adoptive transfer assays were analyzed. Results and Conclusions: Mucosal administration of FVIII‐C2 decreases the titer of anti‐FVIII‐C2 inhibitors after FVIII‐C2 challenge, and decreases the percentage of FVIII‐C2 specific antibodies after challenge with full‐length FVIII. Tolerance induction to FVIII‐C2 is associated with increased IL‐10 production by splenocytes in vitro, and can be adoptively transferred to naïve mice. This study is the first to demonstrate that tolerance to the FVIII‐C2 domain can be induced via the mucosal route. Based on these results, the potential use of FVIII‐specific mucosal tolerance induction as an immunotherapy treatment for anti‐FVIII inhibitor development warrants further investigation.     

Expressional analysis of the silkworm storage protein 1 and identification of its interacting proteins

Storage proteins are haemolymph‐specific proteins in insects, mainly synthesized in the fat body, released into the haemolymph, and then selectively reabsorbed by the fat body before pupation. These storage proteins play an important role in insect metamorphosis and egg development. Some of these storage proteins are responsive to pathogen infection and can even suppress pathogen multiplication. However, the mechanisms of the physiological, biochemical and immune‐responsive functions of storage proteins remain unclear. In this study, the expression patterns of Bombyx mori storage protein 1 (BmSP1) during the larval stage were analysed. Then, BmSP1 protein fused with enhanced green fluorescent protein (EGFP) was successfully expressed in a B. mori baculovirus vector expression system. Quantitative real‐time PCR showed that the expression level of BmSP1 increased with the advance of instars and reached the highest level in the fifth instar, especially in the fat body. Recombinant BmSP1 expressed in silkworm larvae inhibited haemolymph melanization. Then, proteins that interact with BmSP1 were identified with EGFP used as an antigenic determinant by co‐immunoprecipitation. A 30 kDa low molecular weight lipoprotein PBMHP‐6 precursor (BmLP6) was shown to interact with BmSP1. Yeast two‐hybrid experiments confirmed the interaction between BmSP1 and BmLP6. The results obtained in this study will be helpful for further study of the functions of BmSP1 and BmLP6 in the regulatory network of silkworm development and innate immunity.     

Identification,characterization and expression of a defensin‐like antifungal peptide from the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Defensins are a class of small and diverse cysteine‐rich proteins which have broad‐spectrum antimicrobial activities. We identified and characterized a full‐length cDNA encoding a putative defensin‐like peptide from the whitefly Bemisia tabaci by RACE and quantitative real‐time (qRT)‐PCR. The full‐length cDNA, named Btdef, was 388 bp long and contained an open reading frame of 228 bp. The putative mature Btdef had 46 amino acids with a molecular weight of 5.06 kDa. The deduced amino acid sequence showed significant homology with insect defensins from Heliothis virescens (76%) and Galleria mellonella (75%). The predicted mature form of Btdef was expressed as a recombinant peptide in Escherichia coli. Antimicrobial assays of the purified product indicated that Btdef was most active against fungi. qRT‐PCR analyses indicated that Btdef mRNA was constitutively expressed in different tissues of B. tabaci, including fat body, midgut, ovaries and salivary gland, and was induced by fungal infection. Btdef mRNA expression was also significantly altered after feeding on different host plants, indicating that diet affects immune defences in B. tabaci. These results describe for the first time the basic properties of a defensin‐like peptide from B. tabaci that probably plays an important role in the immune response against pathogens.     

Molecular cloning and characterization of a short peptidoglycan recognition protein from silkworm Bombyx mori

Peptidoglycan is the major bacterial component recognized by the insect immune system. Peptidoglycan recognition proteins (PGRPs) are a family of pattern‐recognition receptors that recognize peptidoglycans and modulate innate immune responses. Some PGRPs retain N‐acetylmuramoyl‐L‐alanine amidase (Enzyme Commission number: 3.5.1.28) activity to hydrolyse bacterial peptidoglycans. Others have lost the enzymatic activity and work only as immune receptors. They are all important modulators for innate immunity. Here, we report the cloning and functional analysis of PGRP‐S4, a short‐form PGRP from the domesticated silkworm, Bombyx mori. The PGRP‐S4 gene encodes a protein of 199 amino acids with a signal peptide and a PGRP domain. PGRP‐S4 was expressed in the fat body, haemocytes and midgut. Its expression level was significantly induced by bacterial challenges in the midgut. The recombinant PGRP‐S4 bound bacteria and different peptidoglycans. In addition, it inhibited bacterial growth and hydrolysed an Escherichia coli peptidoglycan in the presence of Zn²⁺. Scanning electron microscopy showed that PGRP‐S4 disrupted the bacterial cell surface. PGRP‐S4 further increased prophenoloxidase activation caused by peptidoglycans. Taken together, our data suggest that B. mori PGRP‐S4 has multiple functions in immunity.     

Generation of a novel factor IX with augmented clotting activities in vitro and in vivo

Summary. Background: Hemophilia B is an X‐linked inherited disorder caused by the lack of functional factor IX (FIX). Currently, treatment of hemophilia B is performed by intravenous infusion of plasma‐derived or recombinant FIX. Objective: In an effort to reduce factor usage and cost, we investigated the potential use of FIX variants with enhanced specific clotting activity. Methods: Seven recombinant FIX variants using alanine replacement were generated and assayed for their activity in vitro and in vivo. Results: One variant containing three substitutions (V86A/E277A/R338A, FIX‐Triple) exhibited 13‐fold higher specific clotting activity and a 10‐fold increased affinity for human FVIIIa compared with FIX‐wild‐type (FIX‐WT) and was thus investigated systematically in vivo. Liver‐specific FIX‐Triple gene expression following hydrodynamic plasmid delivery revealed a 3.5‐fold higher specific clotting activity compared with FIX‐WT. Human FIX‐Triple and FIX‐WT knock‐in mice were generated and it was confirmed that FIX‐Triple has 7‐fold higher specific clotting activity than FIX‐WT under normal physiological conditions. Protein infusion of FIX‐Triple into hemophilia B mice resulted in greater improvement of hemostasis than that achieved with FIX‐WT. Moreover, tail‐vein administration of a serotype 8 recombinant Adeno‐associated vector (AAV8) expressing either FIX‐WT or FIX‐Triple in hemophilia B mice demonstrated a 7‐fold higher specific clotting activity of FIX‐Triple than FIX‐WT. Conclusions: Our results indicate that the FIX‐Triple variant exhibits significantly enhanced clotting activity relative to FIX‐WT due to tighter binding to FVIIIa, as demonstrated both in vitro and in vivo. Therefore, FIX‐Triple is a good candidate for further evaluation in protein replacement therapy as well as gene‐based therapeutic strategies.     

Asymmetric dimethylarginine and total homocysteine in plasma after oral methionine loading

Background: Elevation of homocysteine (Hcy) and asymmetric dimethylarginine (ADMA) in plasma are believed to be involved in the pathogenesis of cardiovascular disease (CVD). In humans, oral methionine loading results in acute elevation of plasma Hcy. This is associated with impaired NO‐dependent vasodilatation, a mechanism that may explain the relationship between elevated Hcy and risk of CVD. ADMA, an endogenous competitive inhibitor of NO‐synthase, may be elevated in plasma of patients with CVD. It was proposed that ADMA is synthesized in a methionine‐dependent reaction which also forms Hcy. In this study plasma total homocysteine (tHcy) and ADMA concentrations were measured before and after oral methionine loading of human subjects. Methods: Plasma tHcy and ADMA levels were measured in 12 healthy males (age 32–58 years) before and after oral loading with L‐methionine (100?mg/kg body weight in orange juice). Results: At noon, 4?h after methionine loading, tHcy and ADMA levels (35.4±10.9 and 0.80±0.13?μmol/L, mean ±SD) were significantly higher than the corresponding values obtained at noon the day before (15.6±7.4 and 0.63±0.10?μmol/L, both p<0.001). Noon values 4?h after methionine loading were also significantly higher than values obtained immediately before the methionine load (13.7±5.9 and 0.66±0.10?μmol/L, both p<0.001). Reinvestigation of 8 of 12 subjects showed that at 4 and 8?h after compared with levels immediately before methionine loading there was a significant increase in tHcy (28.4±10.2 and 33.45±11.1 vs. 10.8±3.3?μmol/L, both p<0.001). However, the corresponding ADMA levels did not increase (0.73±0.17 and 0.76±0.22 vs. 0.70±0.10?μmol/L, both not significant). Conclusions: No clear evidence was found to support the supposition that methionine‐induced hyperhomocysteinaemia may be accompanied by elevated levels of ADMA, an endogenous competitive NO‐synthase inhibitor that may represent an alternative pathogenic mechanism for homocysteine‐associated impairment of endothelial NO‐dependent functions.