Aplicação e significado do diagnóstico sorológico na estrongiloidíase

Parasitological diagnosis based on the faecal examination is frequently difficult in cases of chronic, low-level S. stercoralis infection. Even when a newly developed sensitive method (an agar plate culture) is applied, it is essential to examine faecal samples repeatedly to achieve a correct diagnosis. Additionally, it is important to note that a negative result does not necessarily indicate the unequivocal absence of the infection. On the other hand, several serological tests which have recently been developed for strongyloidiasis have proven reliable when used to complement parasitological examination. We have developed two serological tests, ELISA and GPAT, to demonstrate Strongyloides infection and possible applications of the serological tests for diagnosis, mass-screening, epidemiological study and postchemotherapy evaluation of strongyloidiasis were reviewed based on our recent studies.O diagnóstico parasitológico baseado no exame de fezes é muitas vezes difícil, principalmente nos casos de infecções crônicas ou leves pelo S. stercoralis. Mesmo utilizando o mais novo e sensível método (cultura em placas de ágar) é essencial examinar repetidamente as amostras fecais, para um diagnóstico correto. É importante ressaltar também que o resultado negativo não indica de modo inequívoco a ausência da infecção. Por outro lado, vários testes sorológicos recentemente desenvolvidos para estrongiloidíase tem provado a sua eficácia quando usados para complementar exames parasitológicos. Para demonstrar infecção por Strongyloides desenvolvemos dois tipos de testes sorológicos - ELISA e GPAT - e, com base em nossos recentes estudos, apresentamos uma opinião sobre sua possível aplicação para screening em massa, estudos epidemiológicos e avaliação pós-tratamento de estrongiloidíases

EPIDEMIOLOGICAL FEATURES OF STRONGYLOIDES INFECTION IN OKINAWA, JAPAN : COMPARATIVE STUDY WITH OTHER ENDEMIC AREAS

The epidemiological features of Strongyloides stercoralis infection in Okinawa, Japan, were studied by comparing with those in Thailand, Laos and Brazil. The prevalence rates of Strongyloides infection in the present study were 9.6% (133/1, 380) in Okinawa, 47.6% (99/208) in Chiang Mai, Thailand, 23.8% (106/445) in Khammouane, Laos, and 12.0% (32/267) in Maceio, Brazil, respectively. The age inclination in aged subjects and sex dominance in males were significant features of Strongyloides infection in Okinawa, suggesting that new infection from the environment does not occur in present-day Okinawa. The epidemiological feature was considered to provide a favorable field to investigate therapeutic efficacy unaffected by reinfection from environment after treatment. Absence of helminth infection other than Strongyloides was an additional feature in Okinawa. The features may also be convenient to study host response and pathogenicity in the Strongyloides infection unaffected by concurrent infection with other helminths

Association of a sex-related difference of Strongyloides stercoralis-specific IgG4 antibody titer with the efficacy of treatment of strongyloidiasis

It is difficult to completely eradicate strongyloidiasis, a human intestinal nematode infection with Strongyloides stercoralis with drugs, especially in males. To find host factors involved in the response to treatment, patients infected with S. stercoralis were examined for S. stercoralis-specific antibody titers and the effect of treatment with albendazole on these titers were determined. The cure rate was slightly but not significantly lower in males than in females (P = 0.108). However, a significantly higher titer of S. stercoralis-specific IgG4 antibody was observed in males than in females (P = 0.0097), and the S. stercoralis-specific IgG4 antibody titer was significantly higher in the male non-cured group than in the cured group (P = 0.035). These results suggest that elevation of the S. stercoralis-specific IgG4 antibody titer is associated with resistance to treatment of S. stercoralis infection, especially in males

Production of a high level of specific IgG4 antibody associated with resistance to albendazole treatment in HLA-DRBI*0901-positive patients with strongyloidiasis

Strongyloidiasis, a human intestinal infection with Strongyloides stercoralis, is difficult to treat with drugs. The factors influencing this phenomenon remain unclear. To determine the host factors involved in response to treatment, 46 patients with strongyloidiasis were treated with albendazole, followed-up for 1 year, and separated into two groups: cured and non-cured, Serum levels of specific IgA, IgE, IgG, IgG1, and IgC4 antibodies were estimated using S. stercoralis antigen. Significantly higher titers of IgG4 antibody were observed in the non-cured group than in the cured group (P = 0.016). A total of 88 patients were typed for HLA-DRB1 alleles and analyzed for serum levels of antibody. The S. stercoralis-specific IgG4 antibody titers were significantly higher in the HLA-DRB1*0901-positive group than in the negative group (corrected P = 0.044). These results suggest that HLA-DRB1*0901 is a possible genetic marker for resistance to treatment of S. stercoralis that is associated with elevation of S. stercoralis-specific IgG4 antibody titer