Temporal trends in the incidence of HIV infection in antenatal clinic attendees in Addis Ababa, Ethiopia, 1995-2003.

BACKGROUND: The HIV incidence data are relevant in depicting the current dynamics and trend of the epidemic. Using a new laboratory method for HIV-1 incidence, we aimed at estimating a 10-year trend in HIV-1 incidence in Addis Ababa, Ethiopia. METHODS: We determined the temporal trends in HIV incidence based on a total of 7744 serum specimens from pregnant women who attended antenatal clinics in Addis Ababa between 1995 and 2003. HIV incidence was determined by IgG-capture HIV-1 BED incidence enzyme immunoassay following a validation using a well-characterized panel of serial serum specimens from subtype C-infected seroconverters. FINDINGS: Of the 1350 HIV+ specimens tested as part of the annual sentinel survey between 1995 and 2003, a total of 1332 (98.7%) were tested by BED HIV-1 incidence assay. The incidence rate of HIV-1 infection declined significantly from 7.7% (95% CI, 3.9-11.5%) in 1995 to 2.0% (95% CI, 0.7-3.3%) in 2003. Although there was a trend, amongst the age group of 15-29 years, in age-specific decline in incidence, it was not statistically significant. No change in HIV incidence rate was observed for the group aged above 30 years. INTERPRETATION: A corresponding decline in the incidence of HIV infection was observed with the decline in the prevalence of HIV infection between 1995 and 2003 in Addis Ababa City. Whether the declines were because of changes in sexual behaviours or other reasons needs to be explored. The BED HIV-1 incidence assay provides a valuable tool in obtaining information on recent HIV-1 infection.

Persistent diarrhea signals a critical period of increased diarrhea burdens and nutritional shortfalls: a prospective cohort study among children in northeastern Brazil.

Persistent diarrhea (PD; duration >/=14 days) is a growing part of the global burden of diarrheal diseases. A 45-month prospective cohort study (with illness, nutritional, and microbiologic surveillance) was conducted in a shantytown in northeastern Brazil, to elucidate the epidemiology, nutritional impact, and causes of PD in early childhood (0-3 years of age). A nested case-control design was used to examine children's diarrhea burden and nutritional status before and after a first PD illness. PD illnesses accounted for 8% of episodes and 34% of days of diarrhea. First PD illnesses were preceded by a doubling of acute diarrhea burdens, were followed by further 2.6-3.5-fold increased diarrhea burdens for 18 months, and were associated with acute weight shortfalls. Exclusively breast-fed children had 8-fold lower diarrhea rates than did weaned children. PD-associated etiologic agents included Cryptosporidium, Giardia, enteric adenoviruses, and enterotoxigenic Escherichia coli. PD signals growth shortfalls and increased diarrhea burdens; children with PD merit extended support, and the illness warrants further study to elucidate its prevention, treatment, and impact.

Longitudinal study of Cryptosporidium infection in children in northeastern Brazil.

A prospective, 4-year cohort study of children born in an urban slum in northeastern Brazil was undertaken to elucidate the epidemiology of Cryptosporidium infection in an endemic setting, describe factors associated with Cryptosporidium-associated persistent diarrhea, and clarify the importance of copathogens in symptomatic cryptosporidiosis. A total of 1476 episodes of diarrhea, accounting for 7581 days of illness (5.25 episodes/child-year), were recorded: of these, 102 episodes (6.9%) were persistent. Cryptosporidium oocysts were identified in 7.4% of all stools, and they were found more frequently in children with persistent diarrhea (16.5%) than in those with acute (8.4%) or no (4.0%) diarrhea (P<.001). Low-birth-weight children and those living in densely crowded subdivisions were at greater risk for symptomatic infection. Disease course was highly variable and was not associated with the presence of copathogens. Recurrent Cryptosporidium infection and relapsing diarrhea associated with it were moderately common. In light of these data, the applicability of the current World Health Organization diarrheal definitions to Cryptosporidium-associated diarrheal episodes may need to be reconsidered.

Cryptosporidiosis in northeastern Brazilian children: association with increased diarrhea morbidity.

To evaluate the impact of Cryptosporidium infection on diarrheal disease burden and nutrition status, a nested case-control study was done among children who were followed from birth in Fortaleza, Brazil. The diarrhea history and growth records of 43 children with a symptomatic diarrhea episode of cryptosporidiosis (case-children) were compared with those of 43 age-matched controls with no history of cryptosporidiosis. After Cryptosporidium infection, case-children < or = 1 year old experienced an excessive and protracted (nearly 2 years) diarrheal disease burden. Case-children < or = 1 year old with no history of diarrhea prior to their Cryptosporidium infection also experienced a subsequent increased diarrheal disease burden with an associated decline in growth. Control subjects experienced no change in their diarrhea burden over time. This study suggests that an episode of symptomatic Cryptosporidium infection in children < or = 1 year of age is a marker for increased diarrhea morbidity.

Seroepidemiology of Entamoeba histolytica in a slum in northeastern Brazil.

Infection with the human pathogenic parasite Entamoeba histolytica has not been well-characterized in northeastern Brazil. In this study, the prevalence of E. histolytica infection in a slum in northeastern Brazil was assayed using an enzyme-linked immunosorbent assay (ELISA) for antibodies against the galactose/N-acetyl-D-galactosamine (Gal/GalNAc)-inhibitable adherence lectin of E. histolytica. Sera from a total of 335 individuals were examined for anti-Gal/GalNAc lectin antibodies. The overall seropositivity was 24.7%; 29.4% of females and 19.4% of males were positive. Among different age groups there was a peak of 40% positivity in the 6-14-year-old age group. There was also familial clustering of seropositivity. To examine colonization, stool samples from 155 people were examined microscopically for the presence of the parasite. Fourteen of 155 stools (9.0%) were identified as containing E. histolytica or nonpathogenic E. dispar. These 14 positive stools were analyzed with an ELISA that detects Gal/GalNAc lectin antigen and can distinguish between E. histolytica and E. dispar. Four stools (29%) were positive for E. histolytica and the remaining 10 were identified as E. dispar-positive. Although the overall colonization rate by microscopy was only 9%, with a third identified as E. histolytica, up to 40% of older children develop serologic evidence of having experienced pathogenic E. histolytica infection. The results of this study demonstrate that this community in northeastern Brazil is highly endemic for E. histolytica with infection rates similar to other developing nations.

Cryptosporidial and microsporidial infections in human immunodeficiency virus-infected patients in northeastern Brazil.

To determine the frequency of the parasitic pathogens in human immunodeficiency virus (HIV)-infected patients in a developing world setting, 295 stool specimens were examined from 166 HIV-positive patients (49% with AIDS) at São José Hospital, Fortaleza, Brazil, from September 1990 to March 1992. Significantly more patients with diarrhea (85%) than without (66%) had AIDS or AIDS-related complex (ARC) (P < .005). Of the potential parasitic causes of diarrhea, only Cryptosporidium parvum and microsporidia were significantly associated with diarrheal disease. Infections with C. parvum, but not microsporidia, were associated with the rainy season (P < .005). Thus, C. parvum and microsporidia are the most common intestinal parasites associated with diarrhea in an HIV-infected population in Brazil and are associated with advanced HIV disease. The association of C. parvum infections with the rainy season suggests that contaminated water may be important in its transmission; however, the source of human microsporidia requires further investigation.

Household epidemiology of Cryptosporidium parvum infection in an urban community in northeast Brazil.

OBJECTIVE: To examine the transmission of Cryptosporidium infection in households with an identified person with cryptosporidiosis. DESIGN: Prospective cohort study. SETTING: An urban slum in Fortaleza, Brazil. PARTICIPANTS: Thirty-one households with a child less than 3 years of age (index case) who was positive for Cryptosporidium parvum using acid-fast and auramine-stained stool smears. MEASUREMENTS: Three stool samples (at 0, 2, and 6 weeks after identification of the index case) and two serum samples (0 and 6 weeks) were collected from each family member in households with an index case of Cryptosporidium infection. RESULTS: Forty-five percent of index cases of Cryptosporidium infection were associated with persistent (> 14 days) diarrhea. Secondary cases of Cryptosporidium infection were identified either by stool examination or seroconversion in 18 (58%) of 31 households involving 30 persons, yielding an overall transmission rate of 19%. Of the 202 persons in this study with at least one serum sample available for analysis, 191 (94.6%) had evidence of antibodies (either IgM or IgG) to Cryptosporidium. CONCLUSIONS: Cryptosporidium parvum is highly transmissible and infective in the family setting, with transmission rates similar to other highly infectious enteric pathogens such as Shigella species. These data are cause for added concern because of the rapidly increasing rate of seropositivity for human immunodeficiency virus.

PIP: Between December 1990 and April 1992 investigators enrolled 31 households with a less than 3-year-old child infected with Cryptosporidium parvum in a prospective cohort study to determine the infectivity of Cryptosporidium parvum in families living in crowded conditions, mainly in the Goncalves Dias slum in Fortaleza, Brazil. The median household size was 7. The median age of the 33 index cases was 11 months, while the median age of the 192 family contacts was 21 years. 94% of the index cases had diarrhea at the time Cryptosporidium infection was diagnosed. 45% of the index cases had persistent diarrhea ( 14 days). The median duration of diarrhea was 14 days (range, 1-84 days). Most index cases (83%) had at least 1 other positive stool test for Cryptosporidium. Just 1 index case shed oocysts for 6 weeks. Index cases transmitted Cryptosporidium infection to 30 (19%) of 182 household contacts as evidenced by either a positive stool examination or seroconversion. These 30 secondary cases were from 18 of the 31 households. Only 8 (27%) secondary cases had diarrhea and 25% of them had persistent diarrhea, suggesting preexisting protective immunity in this area where Cryptosporidium infection is endemic. Household contacts who were 5 years old or younger were significantly more likely to have been diagnosed with Cryptosporidium than were those older than 5 years (30% vs. 5%; p 0.001). Most persons with at least 1 serum sample available for analysis (191/202 = 94.6%) had antibodies (IgM or IgG) to Cryptosporidium. The high rate of transmission of Cryptosporidium in this population, the serious threat of persistent diarrhea among young children, and the ever increasing rate of HIV transmission in Brazil (especially among slum dwellers with no access to condoms and to education about AIDS) should raise great concern.

Evaluation of an antigen capture enzyme-linked immunosorbent assay for detection of Cryptosporidium oocysts.

The diagnosis of the small (4- to 6-microns) Cryptosporidium oocysts is labor intensive and relies on stool concentration, with subsequent staining and microscopy. The primary purpose of this study was to evaluate the clinical utility of an antigen capture enzyme-linked immunosorbent assay (ELISA) (LMD Laboratories, Carlsbad, Calif.) in detecting Cryptosporidium oocysts in human stools. A total of 591 specimens (76 diarrheal, 515 control) obtained from 213 inhabitants of an urban slum in northeastern Brazil were examined by both ELISA and conventional microscopic examination (CME) of formalin-ethyl acetate-concentrated stool samples stained with modified acid-fast and auramine stains. Forty-eight diarrheal stools (63.2%) were positive for Cryptosporidium oocysts by CME, with 40 of these positive by ELISA. Thirty-five control stools (6.8%) had Cryptosporidium oocysts detected by CME, with 15 of these also positive by ELISA. All of the 480 nondiarrheal stools and all but one of the diarrheal stools negative by CME were negative by ELISA. The test had an overall sensitivity of 66.3% and a specificity of 99.8% (positive predictive value, 98.2%; negative predictive value, 94.8%). In the evaluation of human diarrheal stool samples, the test sensitivity increased to 83.3%, with a specificity of 96.4%, and, in analysis of samples from individual patients with diarrhea, the sensitivity was 87.9%, with a specificity of 100%. These results indicate that this stool ELISA is sensitive and specific for the detection of Cryptosporidium oocysts in human diarrheal stool specimens but has limited use in epidemiologic studies for the diagnosis of asymptomatic Cryptosporidium infection.

Environmental sources of Cryptosporidium in an urban slum in northeastern Brazil.

Cryptosporidium is an important cause of diarrheal disease in children worldwide. To elucidate the environmental sources of this parasite, we selected an urban slum in Fortaleza, Brazil, a community with a known high incidence of cryptosporidiosis, and examined both stool smears from household animals (n = 127) and filtrates from local water sources (n = 18) for Cryptosporidium oocysts. Because previous work in this community has demonstrated the seasonal nature of human infection with Cryptosporidium, collections were made separately for the dry and rainy seasons. Of the 64 stools collected during the dry season (September-December 1990), four (6.3%) were positive by acid-fast staining for Cryptosporidium. Of the 63 rainy season samples (March-May 1991), nine (14.3%) were positive. Overall, oocysts were detected in 13 (10.2%) of 127 animal stool samples. Freshwater samples were obtained from a variety of sources including open and closed wells, and running city water and then processed. Four of 18 samples (22.2%), including a sample from city water were positive by at least one of two staining techniques (acid-fast and immunofluorescence). In summary, animals may serve as a reservoir of Cryptosporidium, with potential for the contamination of immediate household water sources. These findings may help to explain the high incidence of cryptosporidiosis among infants in this impoverished community.