Trypanosoma cruzi defined antigens in the serological evaluation of an outbreak of acute Chagas disease in Brazil (Catolé do Rocha, Paraíba)

Immunoglobulin G and M humoral response to recombinant protein B13 and glycoconjugate LPPG Trypanosoma cruzi defined antigens was evaluated by ELISA in 18 patients in the acute phase of Chagas disease, who were contaminated on the same occasion. LPPG showed 100% positivity detecting both IgM and IgG antibodies, while positivity of 55-65% was observed for B13. An epimastigote alkaline extract (EPI) also showed high sensitivity for acute IgM (100%) and IgG (90%) antibodies. However LPPG had better discriminatory reactivity since with EPI two patients showed negative IgG and several other sera presented OD values for IgG and IgM antibodies very close to the cutoff. Thus, it is suggested that detection of IgM antibodies by LPPG may be used for diagnosis of the acute phase of Chagas disease. An intense decline of IgG and IgM antibodies to the three antigens was observed in response to anti-T. cruzi chemotherapy in all acute phase patients. After treatment, six (30%) individuals maintained IgG positivity to EPI, LPPG, and B13 with lower reactivity than that measured at the acute phase. For comparison, serology of a group of 22 patients in the chronic phase of Chagas disease and also submitted to chemotherapy was determined. Positive IgM antibodies to EPI, LPPG and B13 were detected in only 5-9% cases. In all chronic-phase patients IgG antibodies highly reactive to the three antigens were present and no significant decrease resulted after benznidazole administration. These observations reinforce previous reports that treatment in the acute phase may reduce or eliminate the parasite.

An outbreak of gastroenteritis associated with astrovirus serotype 1 in a day care center, in Rio de Janeiro, Brazil

Between June 4th and June 20th1996 rotavirus, adenovirus, and astrovirus (HAstrV) were investigated in fecal samples from 27 children under three years old with acute diarrhea, attending the Bertha Lutz day care center, in Rio de Janeiro. All fecal samples were analyzed by polyacrylamide gel electrophoresis (PAGE), reverse transcriptase polymerase chain reaction (RT-PCR), enzyme immunoassays (EIA), and electron microscopy (EM). Nine of them (33%) showed positive results for HAstrV by at least one of the employed methodologies. Eight were positive by RT-PCR and EIA, and six by EM. All positive samples were inoculated onto HT-29 (human colon adenocarcinoma) cultured cells for HAstrV isolation and seven were positive after three passages. The sequencing analysis of eight RT-PCR products (449 bp) from gene that codifies VP2 protein, showed a total nucleotide identity among them and 98% with HAstrV-1 (strain Oxford type 1). This is the first report of a gastroenteritis outbreak associated with HAstrv-1 in a day care center in Rio de Janeiro and it reinforces the importance of this virus in association with infantile acute gastroenteritis.

Hepatitis A Outbreak in a Public School in Rio de Janeiro, Brazil

From June 1 to July 1 1999, an outbreak involving 25 cases of hepatitis A occurred in a public school in Rio de Janeiro, Brazil. Since these cases were notified to the State Health Department, the National Reference Center for Hepatitis Viruses (CNRHV) was required to investigate the extent of hepatitis A virus (HAV) dissemination. Blood samples from all students were tested for IgM and total anti-HAV antibodies using a commercial enzyme-linked immunoassay (ELISA). At the same time, a questionnaire was completed in order to identify possible risk factors for HAV infection. The environmental investigation showed that there was no fecal contamination of the water supply. The epidemiological investigation demonstrated that almost 50% of this population was susceptible to HAV infection and probably person-to-person transmission was the principal mode of virus dissemination. In this situation, a massive vaccination campaign could control the HAV infection.

Acute schistosomiasis outbreak in the metropolitan area of Belo Horizonte, Minas Gerais: alert about the risk of unnoticed transmission increased by growing rural tourism

The present article describes the occurrence of 17 cases of acute schistosomiasis in the metropolitan area of Belo Horizonte, state of Minas Gerais, Brazil. All individuals affected took a bath in a swimming pool of a holiday resort that was provided with water from a nearby brook. The apparently clean water and the absence of snails in the pool gave the wrong impression that there was no risk for infection. During a malacological survey at the site snails of the species Biomphalaria glabrata were found and tested positive for Schistosoma mansoni. All the patients live in the middle-class area of Barreiro, metropolitan area of Belo Horizonte and have medium grade school education. The difficulties in establishing the right diagnosis is expressed by the search for medical attention in 17 different medical facilities, the wide range of laboratory test and the inadequate treatment administration. A lack of knowledge about the disease was found in all groups studied. The booming rural tourism in endemic areas is identified as a probable risk factor for infection, especially for individuals of the non-immune middle and upper class parts of the society in urban centers. Special attention is given to a multidisciplinary approach to the complex issue of disease control and prevention.

Tegumentary leishmaniasis outbreak in Bella Vista City, Corrientes, Argentina during 2003

Bella Vista City, Corrientes, Argentina, reported an epidemic outbreak of tegumentary leishmaniasis during 2003. The mean age of the 31 cases was 25.0 ± 13.7 years old, with a sex ratio male:female 1.8, and without mucosal involvement. They clustered in two contiguous neighbourhoods, 96% in the periurban border and 4% in the peripheral outskirts. The transmission peak was estimated to have occurred during April 2003. Four species (3608 sand flies) were captured in nine sites: Lutzomyia neivai (90.1%), Lu. pessoai (8.9%), Lu. migonei (0.8 %), and Brumptomyia avellari (0.2 %). The outskirts/rural capture ratio of Lu. neivai was up to 3, and the outskirts/periurban up to 200. Therefore, the 'urban' transmission in this southernmost known focus is still an ecotone-border associated risk. The changes in human distribution or activities, patches of the secondary vegetation, periurban streams, rainfall of the previous year, and river period floods could all contribute to 'urban' outbreaks in the region. Tegumentary leishmaniasis risk should be assessed for any project that involves changes in land use throughout an endemic area.

Hepatitis A virus subgenotypes dissemination during a community outbreak in a surrounding region of Rio de Janeiro

From December 1999 to December 2001, many cases of hepatitis A were notified in the county of Belford Roxo involving individuals aged 0 to 79 years. Serum samples were collected to evaluate the prevalence of anti-hepatitis A virus (HAV) antibodies, to detect HAV-RNA and to correlate with possible risk factors of HAV infection. Serum samples were screened by commercial IgM and total anti-HAV antibody ELISA and HAV-RNA was isolated and subsequently amplified by reverse transcription-polymerase chain reaction (RT-PCR) at VP1/2A region, sequenced and analyzed. Total anti-HAV prevalence was 87.9% (203/231) and IgM anti-HAV prevalence was 38.7% (89/231). Multivariate analysis showed that individuals under 20 years old are risks groups to acquire the infection suggesting that hygienic habits of young subjects are the principal factor of transmission and so they could be the target for vaccine programs. HAV-RNA was amplified from 29 (32.5%) IgM anti-HAV positive patients and 26 samples were sequenced and classified into subgenotypes IB (8 isolates) and IA (18 isolates). Isolates classified into subgenotype IB were identical representing one distinct strain. We could observe both subgenotypes circulating during the study which suggests different sources of infection. Prophylactic measures as vaccination strategies added to improvements in hygienic and sanitary conditions would be highly effective to reduction of infection.

Dynamics of the 2006/2007 dengue outbreak in Brazil

We analyzed dengue incidence in the period between October 2006-July 2007 of 146 cities around the country were Larval Index Rapid Assay (LIRA) surveillance was carried out in October 2006. Of these, we chosen 61 cities that had 500 or more cases reported during this period. We calculated the incidence coefficient, the force of infection (») and the basic reproduction number (R0) of dengue in those 61 cities and correlated those variables with the LIRA. We concluded that » and R0 are more associated with the number of cases than LIRA. In addition, the average R0 for the 2006/2007 dengue season was almost as high as that calculated for the 2001/2002 season, the worst in Brazilian history.

Outbreak of Rocky Mountain spotted fever in Córdoba, Colombia

Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the obligate intracellular bacterium Rickettsia rickettsii. Although RMSF was first reported in Colombia in 1937, it remains a neglected disease. Herein, we describe the investigation of a large cluster of cases of spotted fever rickettsiosis in a new area of Colombia.

The endemisation of schistosomiasis in Porto de Galinhas, Pernambuco, Brazil, 10 years after the first epidemic outbreak

In 2000, after heavy rains and floods in Porto de Galinhas, Pernambuco, Brazil, an outbreak of schistosomiasis was recorded, of which 62.2% (412 cases) were of the acute clinical form. Between 2001-2009, occasional findings of Biomphalaria snails parasitised by Schistosoma mansoni indicated that disease transmission was still occurring. This motivated a new epidemiological survey between August-December 2010 to provide an update of the occurrence of this health hazard and to investigate the process of disease endemisation at this locality. This survey gathered parasitological, clinical and malacological data. The results of this survey, compared with data from the year 2000 survey, showed the following: (i) over these 10 years, there were declines in the total percentage of cases and the percentage of acute forms, (ii) the acute clinical form now represents 23.3% in contrast with the 62.2% detected in 2000 and (iii) the current prevalence of schistosomiasis is 15.7%, while in 2000 32.1% of the individuals were diagnosed as parasitised. Today, the chronic clinical form represents 76.7% of the total number of cases diagnosed, thus showing that over the 10-year period the occurrences of clinical forms became inverted. These findings, together with visual observation of insalubrious environmental conditions, indicate that schistosomiasis has become endemic in Porto de Galinhas.

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8% suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68% of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Biological, biochemical and molecular features of Trypanosoma cruzi strains isolated from patients infected through oral transmission during a 2005 outbreak in the state of Santa Catarina, Brazil: its correspondence with the new T. cruzi Taxonomy Consensus (2009)

We examined strains of Trypanosoma cruzi isolated from patients with acute Chagas disease that had been acquired by oral transmission in the state of Santa Catarina, Brazil (2005) and two isolates that had been obtained from a marsupial (Didelphis aurita) and a vector (Triatoma tibiamaculata). These strains were characterised through their biological behaviour and isoenzymic profiles and genotyped according to the new Taxonomy Consensus (2009) based on the discrete typing unities, that is, T. cruzi genotypes I-VI. All strains exhibited the biological behaviour of biodeme type II. In six isolates, late peaks of parasitaemia, beyond the 20th day, suggested a double infection with biodemes II + III. Isoenzymes revealed Z2 or mixed Z1 and Z2 profiles. Genotyping was performed using three polymorphic genes (cytochrome oxidase II, spliced leader intergenic region and 24Sα rRNA) and the restriction fragment length polymorphism of the kDNA minicircles. Based on these markers, all but four isolates were characterised as T. cruzi II genotypes. Four mixed populations were identified: SC90, SC93 and SC97 (T. cruzi I + T. cruzi II) and SC95 (T. cruzi I + T. cruzi VI). Comparison of the results obtained by different methods was essential for the correct identification of the mixed populations and major lineages involved indicating that characterisation by different methods can provide new insights into the relationship between phenotypic and genotypic aspects of parasite behaviour.

The performance of laboratory tests in the management of a large outbreak of orally transmitted Chagas disease

Orally transmitted Chagas disease (ChD), which is a well-known entity in the Brazilian Amazon Region, was first documented in Venezuela in December 2007, when 103 people attending an urban public school in Caracas became infected by ingesting juice that was contaminated with Trypanosoma cruzi. The infection occurred 45-50 days prior to the initiation of the sampling performed in the current study. Parasitological methods were used to diagnose the first nine symptomatic patients; T. cruzi was found in all of them. However, because this outbreak was managed as a sudden emergency during Christmas time, we needed to rapidly evaluate 1,000 people at risk, so we decided to use conventional serology to detect specific IgM and IgG antibodies via ELISA as well as indirect haemagglutination, which produced positive test results for 9.1%, 11.9% and 9.9% of the individuals tested, respectively. In other more restricted patient groups, polymerase chain reaction (PCR) provided more sensitive results (80.4%) than blood cultures (16.2%) and animal inoculations (11.6%). Although the classical diagnosis of acute ChD is mainly based on parasitological findings, highly sensitive and specific serological techniques can provide rapid results during large and severe outbreaks, as described herein. The use of these serological techniques allows prompt treatment of all individuals suspected of being infected, resulting in reduced rates of morbidity and mortality.