Serological investigation to identify risk factors for post-flood infectious diseases: a longitudinal survey among people displaced by Typhoon Morakot in Taiwan

OBJECTIVES

After Typhoon Morakot struck Taiwan in 2009, thousands of Taiwanese citizens were displaced to shelters for several weeks. Others were placed in urban communities where they had family members. This study aimed to investigate serological status in both groups and identify risk factors associated with seroconversion of infectious diseases.

DESIGN

A longitudinal survey.

SETTING

All experimental and clinical investigations were performed in a tertiary teaching hospital.

PARTICIPANTS

A total of 288 displaced persons (96 males and 192 females) were recruited and complete follow-up data through two rounds of sampling were collected. The average age was 58.42 years (range 31-87 years).

INTERVENTIONS

First, serum specimens were collected between December 2009 and January 2010, 4-5 months after the typhoon. The second round of specimen collection was carried out after 6 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measured was serological status of vaccine-preventable droplet-borne infectious diseases (ie, measles, mumps, rubella) and water-borne diseases (ie, amoebiasis and leptospirosis). The secondary outcome was identification of risk factors for seroconversion using univariate and multivariate analyses.

RESULTS

Complete data were available for all 288 displaced persons (114 from the shelter group; 174 from the community group). Seroconversion of Entamoeba histolytica was observed in 128 (44.4%) participants, with a significantly higher rate in the shelter group than in the community group (56.1% vs 36.8%; p=0.001). There were 10 cases of rubella seroconversion. After adjusting for medical history, hypertension and hyperlipidaemia, shelter stay was associated with higher risk for seroconversion (OR=2.055, 95% CI 1.251 to 3.374; p=0.004). Amoebiasis was more evident in the shelter group, although the manifestations were mild.

CONCLUSIONS

Our results suggested that (1) a clean water supply is essential postdisaster, especially in crowded shelters, and (2) vaccination programmes should be extended to populations at higher risk for post-disaster displacement or to those with weakened immune status.

Amoebic gill disease resistance is not related to the systemic antibody response of Atlantic salmon, Salmo salar L

Amoebic gill disease (AGD) is a proliferative gill tissue response caused by Neoparamoeba perurans and is the main disease affecting Australian marine farmed Atlantic salmon. We have previously proposed that macroscopic gill health ('gill score') trajectories and challenge survival provide evidence of a change in the nature of resistance to AGD. In order to examine whether the apparent development of resistance was because of an adaptive response, serum was sequentially sampled from the same individuals over the first three rounds of natural AGD infection and from survivors of a subsequent non-intervention AGD survival challenge. The systemic immune reaction to 'wildtype'Neoparamoeba sp. was characterized by Western blot analysis and differentiated to putative carbohydrate or peptide epitopes by periodate oxidation reactions. The proportion of seropositive fish increased from 46% to 77% with each AGD round. Antibody response to carbohydrate epitope(s) was immunodominant, occurring in 43-64% of samples. Antibodies that bound peptide epitope were identified in 16% of the challenge survivors. A 1:50 (single-dilution) enzyme-linked immunosorbent assay confirmed a measurable immune titre in 13% of the survivors. There was no evidence that antibodies recognizing wildtype Neoparamoeba provided significant protection against AGD.

Th-1/Th-2 cytokine pattern in human amoebic colitis

Amoebiasis, caused by Entamoeba histolytica, is still considered a major health problem in developing countries. Since the immune response during human amoebiasis has not been clearly defined, we chose to evaluate cytokine production in patients suffering from amoebic colitis. A case-control association study was carried out on 62 subjects, including 31 patients with amoebic colitis and 31 healthy controls (age, sex and geographic region-matched). Serum levels of IL-12, IFN-gamma, IL-13 and IL-5 were measured by solid-phase sandwich enzyme linked immunosorbant assay. Serum levels of IFN-gamma, IL-12, IL-13 and IL-5 were higher in the patients with amoebic colitis than in healthy controls, but were only statistically increased for IL-5 (p = 0.04) and IL-13 (p = 0.014). Stratification of patients according to gender revealed that IL-13 was significantly elevated in men as compared to levels measured in women (p = 0.04). These findings suggest that E. histolytica induce a mixed Th-1/Th-2 response with a polarization toward Th-2 during the early stage of amoebiasis, which may aide in developing a clinical illness.

The role of blood vessels and lungs in the dissemination of Naegleria fowleri following intranasal inoculation in mice

Primary amoebic meningoencephalitis (PAM) was induced in mice by intranasal inoculation of Naegleria fowleri (Singh et Das, 1970) to study the role of the blood vessels and lungs in the early and later stages in this disease. Upon culturing blood and lung tissue obtained at 24-, 36-, 48-, 72-, 96-, and 120-hour time periods, it was found that amoebae grew only from blood and lung tissue obtained at the 96 and 120 hour time periods. Paraffin sections of the head revealed small foci of acute inflammation and amoebae within the olfactory bulb of the central nervous system (CNS) at 24 hours. Amoebae were not observed within blood vessels of the CNS until 96 and 120 hours. Also, amoebae were observed within the connective tissue surrounding blood vessels and sutures of the skull, bone marrow, and venous sinusoids between the skull bone tables at 96 and 120 hours. No amoebae or acute inflammatory reactions were observed in the lung sections from any time period and indirect immunofluorescence microscopy was negative for N. fowleri. This study provides evidence that neither blood vessels nor lungs provide routes for N. fowleri to the CNS during the early stages of PAM and that amoebae enter veins of the CNS and bone marrow during later stages of the disease.

Characterization of entamoeba histolytica antigens in circulating immune complexes in sera of patients with amoebiasis

Isolated circulating immune complexes (CICs) from sera of patients with amoebiasis were characterized to determine Entamoeba histolytica antigens that participate in the disease process. In total, 116 serum samples were collected before starting anti-amoebic therapy, and their CICs were isolated by differential polyethylene glycol precipitation. The presence of amoeba-specific antigens in CICs was detected by antigen capture enzyme-linked immunosorbent assay (ELISA) and by immunoblot assay. Antigen capture ELISA showed significantly higher optical density (p < 0.001) in all patients with amoebiasis than in the normal healthy controls and patients of non-amoebic hepatic disorder. Immunoblot assay detected amoeba-specific CICs in all 18 patients (100%) with confirmed amoebic liver abscess, 28 (80%) of 35 patients with clinically-suspected amoebic liver abscess, and 18 (78.26%) of 23 patients with amoebic colitis. No patients with non-amoebic hepatic disorders and healthy control subjects had any detectable level of amoebic antigens in CICs. Immunoblot assay revealed E. histolytica antigens of relative molecular masses of 35, 56, 70, and 90 kDa present in CICs of 64 of 76 patients with amoebiasis. The 35-kDa polypeptide was observed in 52 patients (81.25%). The results of the study suggest that the 35-kDa polypeptide antigen can be a diagnostic marker in active amoebiasis.

Standardized method of measuring acanthamoeba antibodies in sera from healthy human subjects

Acanthamoeba species can cause serious, debilitating, and sometimes life-threatening infections. Three groups have been identified using morphological and immunological comparisons. Previous serological studies have utilized a variety of antigen preparations and assay methods and reported disparate (3 to 100%) results. This study was designed to (i) optimize an enzyme-linked immunosorbent assay for detecting serum antibodies to each of the Acanthamoeba serogroups and (ii) test 55 healthy individuals for specific immunoglobulin G reactivity. The highest signal-to-background ratio was found when 3,000 fixed, intact trophozoites per well were used with a 1:10 serum dilution. Sera yielding optical densities of <0.25 against all three Acanthamoeba serogroups were used to define the cutoff for positive results. The highest background reactivity with these sera was seen with Acanthamoeba polyphaga (serogroup 2), followed by Acanthamoeba culbertsoni (serogroup 3) and Acanthamoeba astronyxis (serogroup 1). Of 55 subjects tested, the highest number of positive results was seen with A. polyphaga (81.8%), followed by A. astronyxis (52.8%) and A. culbertsoni (40%). Seven serum samples (12.7%) were negative for all three Acanthamoeba serogroups, 16 (29.1%) were positive for one serogroup only, 16 were positive for two serogroups, and 16 reacted to all three serogroups. Further analysis showed no significant associations between serogroup reactivity and age or gender. However, some ethnic differences were noted, especially with A. polyphaga antigens. In that case, serum samples from Hispanic subjects were 14.5 times less likely to be positive (P = 0.0025) and had lower mean absorbance values (P = 0.047) than those from Caucasian subjects. Overall, these data suggest that Acanthamoeba colonization or infection is more common than previously thought. Mild or asymptomatic infections may contribute to the observed serum reactivities.

Serum zinc and copper levels in southeastern Turkish children with giardiasis or amebiasis

Alterations of serum zinc (Zn) and copper (Cu) concentrations are commonly found in patients suffering from gastrointestinal infections and with hepatic, renal, cardiovascular, and malignant diseases. In this study, the serum Zn and Cu levels in 20 children with giardiasis and in 40 children with amebiasis were evaluated. The serum Zn levels showed a significant decrease when compared to controls (p<0.001). After metronidazole therapy, a significant increase in Zn levels was observed (p<0.001). There was no significant difference in serum Cu levels between patients and controls before therapy. Before therapy, the serum Cu/Zn ratio in children with either giardiasis or amebiasis was significantly higher than that of the control group. After therapy, the Cu/Zn ratio was found to be back to normal. There were no significant differences in serum Zn levels and Cu/Zn ratios between children with and without diarrhea and there was no significant difference in children with or without failure to thrive. We concluded that Zn deficiency and elevated Cu/Zn ratio could be acute-phase responses to parasitic infections in children with giardiasis or amebiasis and that a successful treatment of the primary disorder will lead to complete recovery. Further studies are in progress to confirm the benefit of Zn supplementation during the acute phase of the disease, particularly in zinc-deficient regions of the world, such as in the case of Turkey.

Immunoblot analysis of IgA antibodies to Naegleria fowleri in human saliva and serum

The objective of this study was to evaluate the secretory IgA (SIgA) antibody response to Naegleria fowleri (Nf) in individuals living in a parasite endemic area. Saliva and serum samples were obtained from both healthy subjects and patients suffering from a respiratory illness (chronic bronchitis or rhinitis) and were analyzed by immunoblot assay. SIgA from the patients' samples recognized more intensely a greater number of Nf proteins than did SIgA from the healthy control group. The proteins more frequently recognized were those with a molecular weight of 171, 107, 102, 62, 50, 46, and 10 kDa. Some IgA antibodies recognized proteins from Nf and Entamoeba histolytica (Eh) of similar molecular weight. These results suggest that some of those antibodies could have been elicited by a previous intestinal infection with Eh. Through the common mucosal immune system the IgA B-cells activated by Eh antigens can be disseminated to all the mucosae, including the nasal mucosa. SIgA antibodies recognizing Nf proteins, induced either by specific immunization or by cross-reaction, could participate in the resistance to the infection, probably by inhibiting the adherence of Nf trophozoites to the nasal mucosa.

Investigation of cross-reactions against Trichinella spiralis antigens by enzyme-linked immunosorbent assay and enzyme-linked immunoelectrotransfer blot assay in patients with various diseases

Data regarding cross-reactions against Trichinella spiralis in humans are scarce and controversial. For this reason, we tested serum samples from patients with typhoid fever, brucellosis, toxoplasmosis, amoebiasis, cysticercosis, trichocephaliasis, ascariasis, and onchocerciasis against an antigenic extract of T. spiralis infective larvae in an enzyme-linked immunosorbent assay (ELISA) and an enzyme-linked immunoelectrotransfer blot (EITB) assay. All except one serum sample from the group of patients with onchocerciasis were negative in the ELISA; in the EITB assay, only faint bands were observed with the samples from patients with onchocerciasis and ascariasis and negative results were obtained with the samples from patients with other diseases. In conclusion, cross-reactions were found only in the groups of patients with other nematode infections and were of very low magnitude, most of them virtually negative.

[Evaluation of an indirect hemagglutination test for the serodiagnosis of amebiasis]

167 sera have been tested to appreciate the value of an indirect hemagglutination test (Amibiase HAI FUMOUZE) comparatively to an agglutination test of sensibilized particles of latex (Bichro latex Amibe Fumouze BLA) Amibiase HAI test comes out as sensitive and specific for the detection of antibodies in patients suffering from visceral amoebiasis. But some antibodies are also detected in patients with an antecedent of amoebiasis, as it is usually the case with some other techniques. A high positivity of the indirect hemagglutination test, and the concordance between the test HAI and the BLA one are in favour of a visceral amoebiasis. While lower rates or discrepancy between the two tests may evoke an hidden infestation in patients coming out or originated from endemic zones.

An assessment of hepatic functional capacities and haemoglobin values in amaebiasis

Fourty adult males with amaebiasis and a match control group of the same age and sex were subjected to complete blood examination. The results showed that the mean values for total serum protein, total serum bilirubin, A.L.P. and Hb % were within the acceptable limits i.e. statistically insignificant, whilst A.S.T. and A.L.T. were not within the acceptable limits, i.e. statistically significant. The percentages of normals as regards the frequency distribution test were as follows: Total serum protein (80%), total serum bilirubin (82.5%), A.L.P. (94.59%), A.S.T. (67.5%), A.L.T. (75%) and Hb. (86.21%). The regression analysis test, confirmed by the correlation test, were performed to indicate the relationship between the intensity of infection (indicated by the population of E. histolytica in stool analysis) and the serum levels of the tests to follow. Accordingly the serum levels of A.L.P., A.S.T. and A.L.T. showed a relatively slight increase, while the total serum protein level and Hb% showed a slight decrease. The serum bilirubin indicated no change whatsoever.

[Serum levels of IgE in children with invasive amebiasis]

In order to determine whether an elevation of the IgE serum level exist in children with invasive amebiasis when compared with a control group, a prospective, observational and descriptive study was performed on 20 patients from the problem group and 21 from a control group, where the possibility of other causes which could raise the IgE levels were dismissed. This antibody was measured in serum and compared with the reported levels of mexican and foreign populations. A notable elevation of the IgE level was found in the studied groups, without any significant differences between them. It wasn't demonstrated that the serum level is as high as immunological response against E. histolytica.

Application of a micro enzyme-linked immunosorbent assay (ELISA) to detection of anti-amebic antibody in various forms of amebic infection

Techniques of a micro enzyme-linked immunosorbent assay (ELISA) used for the serodiagnosis of schistosomiasis were applied to amebic infection. Test sera were divided primary on the basis of serologic diagnosis and stool examination as follows; (I) gel diffusion precipitin test (GDP) positive and stool examination positive: 9 specimens, (II) GDP positive and stool examination negative: 29 specimens, (III) GDP negative and stool examination positive: 32 specimens. Virtually all of the individuals belonging to (III) were asymptomatic, while more than 75% of (I) and (II) were symptomatic. The upper limit of 99% critical range was calculated from the data of 70 serum specimens from healthy adult Japanese and was employed as the cut-off value. All of the specimens of (I) and (II) were judged positive by ELISA, generally with a much higher absorbance than the cut-off value; whereas, approximately 80% of (III) were judged positive. The average absorbance of (III) was lower than that of (I) and (II). These findings suggest that the ELISA is well in accord with GDP qualitatively as far as GDP-positive individuals are concerned, and that even asymptomatic cyst carriers with negative serology by GDP may often be producing anti-amebic antibodies, although the titers are low.

A multicomponent hemolytic system in the pathogenic amoeba Naegleria fowleri

A hemolytic activity associated with postnuclear supernatant fractions of Naegleria fowleri has been partially characterized in an attempt to isolate cytolytic molecules that may participate in naeglerial cytopathogenicity. Hemolysis by naeglerial postnuclear supernatant fractions was sensitive to heat and trypsin hydrolysis, and was inhibited by divalent cations. The majority of the hemolytic activity was nonlatent and associated with a particle fraction sedimenting at 48,000 X g (maximum) for 1 h. This particle-associated hemolytic activity appears to be membrane associated, as high salt concentration, chelating agents, and pH extremes were ineffective in solubilizing the hemolytic activity, whereas treatment with 0.15% Zwittergent 3-12, a dipolar ionic detergent, results in 98% release of the sedimentable hemolysin. The sigmoidal nature of the progress curve of postnuclear supernatant hemolysis, as well as synergistic interactions between fractions of amoebal whole cell extracts, suggests that the hemolytic activity has a multicomponent nature, with at least two and possibly three components participating in the hemolytic event. The significance of these findings in the context of naeglerial cytopathogenicity is discussed.

[Eosinophilia and dormant parasitosis]

The exotic diseases are still far from a daily preoccupation and sometimes face the physician with unusual problems. Two classical situations are reported: eosinophilia of parasitic origin, and three examples of asymptomatic parasitosis. Eosinophilia is a classical sign accompanying multicellular parasites (helminths). The rate depends on the duration of the disease, the type of parasite and the scale of the infestation. Pathological eosinophilia is usually present before diagnosis is possible; hence it is necessary to repeat laboratory examinations. Several parasitic diseases are asymptomatic and, after a long evolution, cause serious complications. Examples quoted are malaria, for which there is no absolute prophylaxis, amoebiasis, which is responsible for hepatic necrosis in patients who have never had dysentery, and schistosomiasis, which insidiously causes irreversible hepatic necrosis and ureteral stenosis. These conditions are becoming increasingly frequent in our countries and call for closer attention.

Immunodiagnosis of amoebiasis

Serological studies were done on 127 cases using three different techniques namely indirect haemagglutination (IHA), indirect fluorescent antibody test (IFT) and counter immunoelectrophoresis (CIEP) to detect antiamoebic antibodies. All amoebic liver abscess cases showed significant titre of antibodies by all the three tests used. In the group of patients suffering from amoebic pathology of liver, 90.47 per cent were positive by IHA, 100 per cent by IFT and 85.71 per cent by CIEP respectively. Among amoebic dysentry and amoebic colitis cases 81.81 per cent and 80.64 per cent respectively were positive by IHA. The corresponding figures for IFT were 100 per cent and 74.19 per cent and for CIEP 90.90 per cent and 64.51 per cent respectively. Follow up study showed no significant fall in antibody titre in nine cases studied upto 10 weeks after treatment. Amoebic antigen could be detected in pus from all the nine cases with amoebic liver abscess by CIEP test.

[Serological diagnosis of human amebiasis using the fluorescent antibody technic]

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Amebiasis in northern Saskatchewan: clinical aspects

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