Detailed clinical and ultrasound examination of children and adolescents in a Schistosoma mansoni endemic area in Kenya: hepatosplenic disease in the absence of portal fibrosis

Hepatosplenic schistosomiasis involving organomegaly, portal fibrosis and portal hypertension has been observed in autopsy studies. Here, we have tested the hypothesis that hepatosplenic disease including organomegaly and markers of increased portal pressure can occur in school aged children in the absence of fibrosis. A case-only study of 96 children aged 7-20 years defined by ultrasound detectable hepatomegaly was undertaken in Makueni district, Kenya. A novel method of clinical examination that involved a consensus scoring by three or four examiners was used to classify children as presenting with severe or moderate hepatosplenic disease after palpation of livers and spleens. Ultrasound examination of livers and spleens was based on the Niamey protocol. Clinical measurements included spleen enlargement along the mid-clavicular and mid-axillary lines, liver enlargement along the mid-sternal (MSL) and mid-clavicular lines, as well as organ consistency. The clinical examination indicated that 9% and 60% of the children had severe or moderate hepatosplenomegaly, respectively. Amongst egg-positive children, all clinical measurements, except MSL liver enlargement, correlated with egg count, as did portal vein diameter, spleen length and liver length measured by ultrasound. Peri-portal fibrosis was not observed in any child, whereas 28% of the children were classified as having increased portal pressure according to World Health Organization criteria. There was no effect of malaria parasitaemia or hepatitis seropositvity on any of the observed parameters. These results indicate that hepatosplenic disease in school-aged children attributable to S. mansoni infection, involving hepatosplenomegaly and increased portal vein diameter, can occur in the absence of peri-portal fibrosis.     

Quantile regression for the statistical analysis of immunological data with many non-detects

Background

Hemolytic uremic syndrome (HUS) leading to acute kidney failure, is a condition linked to the production of primarily Shiga toxin 2 (Stx2) by some E. coli serotypes. We have previously shown that Stx2 A subunit-specific human monoclonal antibody (HuMAb) 5C12, and B subunit-specific HuMAb 5H8 inhibit cultured cell death, and protect mice and piglets from fatal Stx2-intoxication. We have also shown that 5H8 blocks binding of Stx2 to its cell-surface receptor globotriaosyl ceramide (Gb₃), whereas Stx2 when complexed with 5C12 binds Gb₃ with higher affinity than Stx2. The mechanism by which 5C12 neutralizes Stx2 in vitro involves trapping of Stx2 in the recycling endosomes and releasing it into the extracellular environment. Because of the clinical implications associated with the formation of Stx2/antibody complexes and the potential for trapping and clearance through a severely damaged kidney associated with HUS, we investigated the likely site(s) of Stx2/antibody localization and clearance in intoxicated mice treated with antibody or placebo.

Results

Mice were injected with radiolabeled Stx2 (¹²⁵I-Stx2) 4 hours after administration of 5C12, 5H8, or phosphate buffered saline (PBS) and the sites of localization of labeled Stx2, were investigated 3, 24 and 48 hours later. The liver recorded statistically much higher concentrations of labeled Stx2 for groups receiving 5C12 and 5H8 antibodies after 3, 24 and 48?hours, as compared with the PBS group. In contrast, highest levels of labeled Stx2 were detected in the kidneys of the PBS group at all 3 sampling times. Mice receiving either of the two HuMAbs were fully protected against the lethal effect of Stx2, as compared with the fatal outcome of the control group.

Conclusions

The results suggest that HuMAbs 5C12 and 5H8 promoted hepatic accumulation and presumably clearance of toxin/antibody complexes, significantly diverting Stx2 localization in the kidneys, the target of Stx2 and the cause of HUS. This is in contrast to the fatal outcome of the control group receiving PBS. The results also confirm earlier observations that both HuMAbs are highly and equally protective against Stx2 intoxication in mice.     

Challenges of establishing the correct diagnosis of outbreaks of acute febrile illnesses in Africa: the case of a likely Brucella outbreak among nomadic pastoralists, northeast Kenya, March-July 2005

An outbreak of acute febrile illness was reported among Somali pastoralists in remote, arid Northeast Kenya, where drinking raw milk is common. Blood specimens from 12 patients, collected mostly in the late convalescent phase, were tested for viral, bacterial, and parasitic pathogens. All were negative for viral and typhoid serology. Nine patients had Brucella antibodies present by at least one of the tests, four of whom had evidence suggestive of acute infection by the reference serologic microscopic agglutination test. Three patients were positive for leptospiral antibody by immunoglobulin M enzyme-linked immunosorbent assay, and two were positive for malaria. Although sensitive and specific point-of-care testing methods will improve diagnosis of acute febrile illness in developing countries, challenges of interpretation still remain when the outbreaks are remote, specimens collected too late, and positive results for multiple diseases are obtained. Better diagnostics and tools that can decipher overlapping signs and symptoms in such settings are needed.     

In-vivo efficacy of amodiaquine-artesunate in children with uncomplicated Plasmodium falciparum malaria in western Kenya

Objectives  To assess the efficacy of amodiaquine-artesunate in an area with high chloroquine resistance in western Kenya.
Methods  Twenty-eight day in-vivo efficacy trial of amodiaquine-artesunate in 103 children aged 6–59 months in western Kenya with smear-confirmed uncomplicated Plasmodium falciparum malaria.
Results  The 28-day uncorrected adequate clinical and parasitological response (ACPR) was 69.0%, with 15.5% Late Clinical Failure and 15.5% Late Parasitologic Failure rates. The PCR-corrected 28-day ACPR was 90.2%. Clinical risk factors for recurrent infection (recrudescences and reinfections) were lower axillary temperature at enrolment and low weight-for-age Z-score. The presence of single nucleotide polymorphisms pfcrt 76T and pfmdr1 86Y at baseline was associated with increased risk of recurrent infections, both reinfections and recrudescences.
Conclusion  Although artemether-lumefantrine (Coartem^®) is the first line ACT in Kenya, amodiaquine-artesunate is registered as an option for treatment of uncomplicated P. falciparum and remains an effective alternative to Coartem^® in western Kenya. Continued amodiaquine monotherapy in the private sector may jeopardise the future use of amodiaquine-artesunate as an alternative artemisinin-based combination therapy.     

Elevated serum interferon‐α activity in juvenile dermatomyositis: Associations with disease activity at diagnosis and after thirty‐six months of therapy

Objective

Interferon‐α (IFNα) has been implicated in the pathogenesis of juvenile dermatomyositis (DM). The aim of this study was to examine serum IFNα activity in a cohort of children with juvenile DM to determine relationships between IFNα and indicators of disease activity and severity.

Methods

Thirty‐nine children with definite/probable juvenile DM were included in the study. Serum samples were obtained at the time of diagnosis from 18 untreated patients with juvenile DM. Second samples from 11 of these patients were obtained at 24 months, while they were receiving treatment, and third samples were obtained from 7 of these patients at 36 months. The remaining 21 children were studied 36 months after their initial diagnosis. Serum IFNα activity was measured using a functional reporter cell assay.

Results

Patients with juvenile DM had higher serum IFNα activity than both pediatric and adult healthy control subjects. In untreated patients, serum IFNα activity was positively correlated with serum muscle enzyme levels (P < 0.05 for creatine kinase, aspartate aminotransferase, and aldolase) and inversely correlated with the duration of untreated disease (P = 0.017). The tumor necrosis factor α −308A allele was associated with higher serum IFNα levels only in untreated patients (P = 0.030). At 36 months, serum IFNα levels were inversely correlated with muscle enzyme levels in those patients still requiring therapy and with the skin Disease Activity Score in those patients who had completed therapy (P = 0.002).

Conclusion

Serum IFNα activity was associated with higher serum levels of muscle‐derived enzymes and a shorter duration of untreated disease in patients with newly diagnosed juvenile DM and was inversely correlated with measures of chronic disease activity at 36 months postdiagnosis. These data suggest that IFNα could play a role in disease initiation in juvenile DM.

     

Typhoid in Kenya Is Associated with a Dominant Multidrug-Resistant Salmonella enterica Serovar Typhi Haplotype That Is Also Widespread in Southeast Asia

In sub-Saharan Africa, the burden of typhoid fever, caused by Salmonella enterica serovar Typhi, remains largely unknown, in part because of a lack of blood or bone marrow culture facilities. We characterized a total of 323 S. Typhi isolates from outbreaks in Kenya over the period 1988 to 2008 for antimicrobial susceptibilities and phylogenetic relationships using single-nucleotide polymorphism (SNP) analysis. There was a dramatic increase in the number and percentage of multidrug-resistant (MDR) S. Typhi isolates over the study period. Overall, only 54 (16.7%) S. Typhi isolates were fully sensitive, while the majority, 195 (60.4%), were multiply resistant to most commonly available drugs—ampicillin, chloramphenicol, tetracycline, and cotrimoxazole; 74 (22.9%) isolates were resistant to a single antimicrobial, usually ampicillin, cotrimoxazole, or tetracycline. Resistance to these antibiotics was encoded on self-transferrable IncHI1 plasmids of the ST6 sequence type. Of the 94 representative S. Typhi isolates selected for genome-wide haplotype analysis, sensitive isolates fell into several phylogenetically different groups, whereas MDR isolates all belonged to a single haplotype, H58, associated with MDR and decreased ciprofloxacin susceptibility, which is also dominant in many parts of Southeast Asia. Derivatives of the same S. Typhi lineage, H58, are responsible for multidrug resistance in Kenya and parts of Southeast Asia, suggesting intercontinental spread of a single MDR clone. Given the emergence of this aggressive MDR haplotype, careful selection and monitoring of antibiotic usage will be required in Kenya, and potentially other regions of sub-Saharan Africa.Typhoid fever, caused by Salmonella enterica serovar Typhi, is an important disease in many developing countries. It is estimated that there are approximately 22 million typhoid cases and ∼200,000 deaths per year worldwide (10). However, the true global distribution of typhoid fever is not well documented. For example, in Africa the overall burden of typhoid fever remains largely unknown, mainly because facilities capable of performing the blood culture tests essential for diagnosis are absent from many regions. Some local estimates of typhoid incidences in different African regions have been made. Typhoid incidence rates of 39/100,000 and 59/100,000 have been reported for Kenya/East Africa and Egypt, respectively (10, 28), but these figures may be underestimates due to underreporting, as only severely ill patients seek treatment in hospitals. In other studies, Weeramanthri et al. (30) observed that over a 5-year period typhoid remained a common cause of septicemic illness in The Gambia, while in Nigeria (2) and Ghana (5), cases of ileal perforation due to typhoid were documented.Problems are also emerging with the clinical treatment of typhoid in resource-poor settings. For many years, the antibiotics chloramphenicol, ampicillin, and cotrimoxazole formed the mainstays of typhoid treatment. However, outbreaks of multidrug-resistant (MDR) S. Typhi (20, 24, 25) prompted the widespread use of fluoroquinolones, such as ciprofloxacin and ofloxacin. Fluoroquinolone usage was followed by the emergence of nalidixic acid-resistant S. Typhi exhibiting reduced susceptibility to fluoroquinolones in the early 1990s (18, 22), and it has since become widespread (1, 12, 16, 19, 25). Thus, the spread of MDR and fluoroquinolone resistance in S. Typhi presents significant clinical challenges.Better methods for monitoring the emergence and spread of MDR S. Typhi would facilitate disease control and treatment. However, this monophyletic (clonal) pathogen presents particular challenges in this regard. Studies on the population structure of S. Typhi have shown that this human-adapted pathogen exhibits extremely limited genetic variation, challenging our ability to develop discriminatory tools of value in the field (3, 11, 25, 27). However, the application of novel deep-sequencing and bioinformatics approaches has succeeded in stratifying the S. Typhi population into distinct phylogenetic lineages based on over 1,000 single-nucleotide polymorphisms (SNPs) distributed throughout the chromosome. Typing of these chromosomal SNPs allows isolates from typhoid patients to be mapped to specific points on the phylogenetic tree of S. Typhi (11, 27). This provides an unequivocal test of the genetic relatedness of multiple S. Typhi isolates, which can be inferred from their relative positions in the phylogenetic tree. In particular, isolates sharing identical haplotypes, mapping to the leaf nodes of the S. Typhi phylogenetic tree, are deemed to be very closely related even if they are isolated in widely different geographical locations.In Kenya, MDR S. Typhi isolates from adults and school age children associated with sporadic outbreaks in resource-poor settings, especially in slum areas, have been reported (13, 15). Here, we analyzed a collection of 323 S. Typhi isolates from three hospitals in Nairobi, Kenya, between 1988 and 2008 for their population structure. We used a novel SNP-typing method capable of simultaneously interrogating ∼1,500 points of potential variation on the S. Typhi genome in a single DNA sample. Using this powerful high-throughput approach, we show that a particular MDR-associated haplotype, H58, previously shown to be widespread in several countries in Asia, has become dominant in Kenya, replacing more divergent antimicrobial-susceptible S. Typhi strains.     

Neutralizing antibodies to interferon-α and circulating interferon in patients with chronic hepatitis C non-responding to pegylated interferon plus ribavirin re-treated by pegylated interferon-α-2a and ribavirin (ANRS HC16 GAMMATRI substudy)

A lack of antiviral response in patients with chronic hepatitis C treated with pegylated (PEG)‐interferon (IFN)‐α‐2a + ribavirin (RIBA) may be explained by neutralizing antibodies to IFN‐α‐2a. The aim of this study was to assess neutralizing antibodies to IFN‐α‐2a and IFN levels in non‐responder patients who were re‐treated by PEG IFN‐α‐2a and RIBA for 12 weeks. Non‐responders to a first‐line treatment of PEG IFN‐α‐2a + RIBA were included for treatment with PEG IFN‐α‐2a (180 µg/week) + RIBA (1,000 mg/day if <75 kg, 1,200 mg otherwise) for 48 weeks. HCV RNA was measured at week 12. IFN levels and neutralizing antibodies to IFN‐α‐2a were measured retrospectively on stored sera at baseline and weeks 4 and 12, using a quantitative sandwich ELISA for neutralizing antibodies to IFN‐α‐2a. Twenty‐three patients were non‐responders and 19 patients were responders at week 12 of the initial phase of the second‐line treatment. Non‐responders and responders did not differ statistically: baseline age (median age 47 vs. 50 years), HCV RNA (median 6.8 vs. 6.4 log₁₀ copies/ml), gender (70% vs. 73% males), genotype (genotype 1: 91% vs. 80%). The median IFN‐α‐2a levels (pg/ml) at weeks 0, 4, and 12 (interquartile range) did not differ between the 19 responders to initial phase of second‐line treatment and the 23 non‐responders: <3.3 (<3.3–371.4), 1457.3 (106.8–3284.8), and 1,652 (90.8–5,000); 84.5 (3.3–277.4), 1407.4 (120.2–2443.4), and 1620.1 (120.2–2287.1), respectively. Among non‐selected consecutive non‐responder patients, re‐treatment with PEG IFN‐α‐2a + RIBA is associated with virological response regardless of the presence of antibody‐mediated resistance to conventional IFN treatment. J. Med. Virol. 82:2027–2031, 2010. © 2010 Wiley‐Liss, Inc.