Isao Teramoto

High and Heterogeneous Prevalence of Asymptomatic and Sub-microscopic Malaria Infections on Islands in Lake Victoria, Kenya.

Kenya is intensifying its national efforts in malaria control to achieve malaria elimination. Detailed characterization of malaria infection among populations living in the areas where the disease is endemic in Kenya is a crucial priority, especially for planning and evaluating future malaria elimination strategy. This study aimed to investigate the distribution and extent of malaria infection on islands in Lake Victoria of Kenya to aid in designing new interventions for malaria elimination. Five cross-sectional surveys were conducted between January 2012 and August 2014 on four islands (Mfangano, Takawiri, Kibuogi and Ngodhe) in Lake Victoria and a coastal mainland (Ungoye). Malaria prevalence varied significantly among settings: highest in Ungoye, followed by the large island of Mfangano and lowest in the three remaining small islands. Of the 3867 malaria infections detected by PCR, 91.8% were asymptomatic, 50.3% were sub-microscopic, of which 94% were also asymptomatic. We observed geographical differences and age dependency in both proportion of sub-microscopic infections and asymptomatic parasite carriage. Our findings highlighted the local heterogeneity in malaria prevalence on islands and a coastal area in Lake Victoria, and provided support for the inclusion of mass drug administration as a component of the intervention package to eliminate malaria on islands.

Oral inoculation of live or dead third-stage larvae of Anisakis simplex in rats suggests that only live larvae induce production of antibody specific to A. simplex

Live Anisakis simplex third-stage larvae (L3) penetrate gastrointestinal mucosa after they are ingested in raw or undercooked seafood, thereafter causing gastrointestinal manifestations and allergic manifestations such as urticaria and anaphylaxis. These allergic reactions are mediated by specific IgE to L3 allergens, especially excretory-secretory (ES) allergens. Recent evidences suggest that only live larvae can cause allergic reactions, although cases attributable to ingestion of cooked, frozen seafood have been reported. Therefore the risk of Anisakis-associated hypersensitivity by ingestion of properly cooked and frozen fish remains controversial. No prior report describes the kinetics of antibody production in experimental animals after oral inoculation with dead L3. This study used ELISA to assess antibody production in rats inoculated orally with dead L3. Positive absorbance value in IgG, IgM, and IgE specific to ES antigen from L3 were found in rats inoculated with live L3 but not with dead L3 (frozen, heated, cut, or homogenized). At one week post re-inoculation with live or frozen L3 to the initially sensitized rats, the absorbance value of the specific IgM and IgE to ES antigen elevated quickly and highly in rats that had been re-inoculated with live L3, but they decreased slightly or did not change in rats inoculated with frozen L3. These results suggest that only ingestion of live L3 can produce the specific antibody and induce initial and secondary sensitizations to L3.

Rapid and sensitive multiplex single-tube nested PCR for the identification of five human Plasmodium species

Malaria is caused by five species of Plasmodium in humans. Microscopy is currently used for pathogen detection, requiring considerable training and technical expertise as the parasites are often difficult to differentiate morphologically. Rapid diagnostic tests are as reliable as microscopy and offer faster diagnoses but possess lower detection limits and are incapable of distinguishing among the parasitic species. To improve global health efforts towards malaria control, a rapid, sensitive, species-specific, and economically viable diagnostic method is needed. In this study, we designed a malaria diagnostic method involving a multiplex single-tube nested PCR targeting Plasmodium mitochondrial cytochrome c oxidase III and single-stranded tag hybridization chromatographic printed-array strip. The detection sensitivity was found to be at least 40 times higher than that of agarose gel electrophoresis with ethidium bromide. This system also enables the identification of both single- and mixed-species malaria infections. The assay was validated with 152 Kenyan samples; using nested PCR as the standard, the assays sensitivity and specificity were 88.7% and 100.0%, respectively. The turnaround time required, from PCR preparation to signal detection, is 90min. Our method should improve the diagnostic speed, treatment efficacy, and control of malaria, in addition to facilitating surveillance within global malaria eradication programs.

Gnathostomiasis caused by ingestion of raw Oncorhynchus masou ishikawae roe

Dear Editor, Human gnathostomiasis is a well-known larva migrans caused by ingesting Gnathostoma larvae, characterized by cutaneous migratory swellings. We present a case of gnathostomiasis caused by ingesting of raw Oncorhynchus masou ishikawae roe. A 57-year-old Japanese man presented with an itchy migrating eruption on his back. He had caught some Oncorhynchus masou at a mountain stream in Nara Prefecture, Japan, and had eaten the roe marinated with soy sauce. After 3 weeks, he noticed right inguinal pain and erythema. Subsequently, an itchy erythema had developed on the right abdomen, and it moved to the upper back (Fig. 1a). The symptoms and a high eosinophil count (1.67 9 10 cells/L; normal, <0.4 9 10) led to a clinical diagnosis of gnathostomiasis. Skin biopsies were acquired at each end of two branches of a linear erythema on the middle back, which aimed to remove the larva. Histopathological examination showed a dense superficial and deep dermal infiltration of eosinophils (Fig. 1b, c). We also observed denatured collagen fragments, apparently caused by the larva’s transfer (Fig. 1d), without any identifiable parasites. The enzyme-labeled antibody method for a serumspecific antibody against Gnathostoma spp. showed positive results. Because new erythema had developed on his middle back (Fig. 1e), the patient was treated with ivermectin 200 lg/ kg and took the same dose 2 weeks later. After treatment, the