The American Journal of Tropical Medicine and Hygiene - Volume 80, Issue 1, 2009

A woman had cutaneous, mucosal, and possible visceral leishmaniasis simultaneously. Many of her cutaneous lesions consisted of boggy indurations rather than customary papules, nodules, or ulcers. This unusual case was finally cured after four courses of miltefosine, one course of antimony, and two courses of Ambisome.

Prevalence of antibodies against Giardia duodenalis was determined by enzyme-linked immunosorbent assay in serum samples from a national serologic survey of Mexico that included all geographic areas and socioeconomic and demographic data for each person sampled. The country was divided into four regions on the basis of development (high, medium high, medium low, and low). Of 3,461 serum samples tested, 1,914 (55.3%) were positive for IgG antibodies against Giardia duodenalis. Seropositivity was age-specific; the probability of seropositivity increased 4.9-fold (95% confidence interval [CI] = 3.16–7.64) in adolescents 10–19 years of age, 8.0-fold (95% CI = 5.19–12.53) in young adults 20–39 years of age, and 12.6-fold (95% CI = 7.93–20.28) in adults more than 40 years of age. Giardia duodenalis seropositivity was associated with male sex (odds ratio = 1.40, 95% CI = 1.22–1.61). No association was found between seropositivity and socioeconomic variables or regional development status.

We examined 364 school children for intestinal parasites in a sub-urban zone of Caracas, Venezuela. Giardia intestinalis was the most prevalent parasite in stool samples from 34 children. Levels of IgA and IgG antibodies to G. intestinalis were assessed by enzyme-linked immunosorbent assay and Western blot before and after treatment with secnidazole. All patients were cured with a reduction of IgA antibody levels in 26 of 34 children and a reduction in IgG-specific antibody levels in 18 of 34 children. Serum of infected patients reacted with proteins of 14 kD to 137 kD. Some patients did not show a change in IgA serum reactivity for parasite proteins by Western blot after treatment. Seventeen children showed reduction of the reactivity or disappearance of protein reactivity (mainly the 14-kD, 122-kD, and 137-kD proteins). Antibody response was not related to clinical status, but quantitative and qualitative serum antibody response against G. intestinalis infection could be used to assess levels of new protein markers that decrease or disappear with successful chemotherapy.

Giardial diarrhea in a birth cohort of 452 children in an urban slum in South India was characterized. Of the 155 episodes that occurred in 99 children, 73% were acute diarrhea. Children with better educated mothers and a toilet at home had lower odds of acquiring giardial diarrhea, whereas low socioeconomic status and drinking municipal water were associated with greater risk. Children with co-infections tended to have a slightly longer duration of diarrhea (P = 0.061) and showed significantly more wasting after an episode than children with diarrhea resulting from Giardia alone (P = 0.032). Among the 99 cases, 50 diarrheal and 51 asymptomatic Giardia positive samples were genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) at the triose phosphate isomerase gene. Assemblage B was predominant both in giardial diarrhea (80%) and asymptomatic giardiasis (94%). Children with Assemblage A subgroup-II alone or dual infections with both assemblage A and B had diarrhea more frequently (P = 0.07).

No cause of one-third of travelers’ diarrhea (TD) cases can be detected despite microbiologic assessment. We propose that these pathogen-negative TD cases include undetected enterotoxigenic Escherichia coli (ETEC). As a standard in diagnostic microbiology, samples of five E. coli colonies were tested to detect ETEC from stool cultures. We compared the sensitivities and the number of ETEC detected by 20 colonies with those of 5, 10, and 15 colonies. The percent detection of ETEC with five E. coli colonies was significantly different from that using 20 E. coli colonies. Of the 116 subjects studied, the number positive for ETEC for 5, 10, 15 and 20 colonies tested were 22 (19.0%), 37 (31.9%), 45 (38.8%) and 46 (39.7%), respectively. Based on our results, we recommend the testing of at least 10 E. coli colonies for optimum detection of ETEC in patients with TD.

Stool samples from 86 immunocompromised patients (51 human immunodeficiency virus (HIV)–infected patients and 35 patients with haematologic malignancies) were systematically screened for intestinal microspordiosis by microscopic examination and polymerase chain reaction (PCR) using universal primer V1/PMP2. Nine samples (10.5%) showed amplification with the predictive size of fragment (6 from HIV–infected patients and 3 from patients with myeloma). Only 5 out of them (all HIV–infected patients) were revealed positive by microscopy. By means of amplicons fragment size, species–specific primers (V1/EB450, V1/IS500) and sequencing, 3 microsporidia species were for the first time identified in Tunisia: Enterocytozoon bieneusi (3 isolates), Encephelitozoon intestinalis (2 isolates), and Encephalitozoon hellem (1 isolate). Systematic use of such sensitive and discriminative molecular tools will contribute to determining the true prevalence of microsporidiosis in Tunisia and to better management of infected immunocompromised subjects.

Envenoming by Protobothrops mucrosquamatus and Viridovipera stejnegeri accounts for the majority of venomous snakebites in Taiwan. We conducted a retrospective study to systematically examine the clinical manifestations and responses to antivenom therapy after P. mucrosquamatus and V. stejnegeri envenoming. Information on demographic characteristics, treatments, and systemic/local complications were abstracted from medical charts between 1991 and 2006. One hundred forty-nine patients with P. mucrosquamatus envenoming and 51 with V. stejnegeri envenoming were eligible for the final analysis, and they differed in terms of patient age, bite site, local bruising, proportion of patients needing ≥ 3 vials of antivenom, and mean hospital stay. Univariate analysis revealed that P. mucrosquamatus envenoming had a higher risk of developing rhabdomyolysis, cellulitis, necrosis, and skin graft. Our findings suggested that P. mucrosquamatus envenoming was associated with a greater risk of severe clinical events, and monitoring for major clinical complications would be recommended.

Gnathostomiasis is increasingly reported among travelers returning from endemic areas. Between 2000 and 2004, thirteen patients were diagnosed with imported gnathostomiasis and followed for at least 6 months after treatment. Nine patients presented with cutaneous signs, two with gastrointestinal signs, and two with neurological signs. The median age was 38 years and the female/male sex ratio was 1.6. The patients had visited South East Asia or Central America. The median interval between symptom onset and treatment (with albendazole in 12 cases and ivermectin in one case) was 3.5 months. Post-treatment follow-up lasted a median of 15 months. Eight patients relapsed, a median of 2 months (1–7 months) after initial treatment. These eight patients had a total of 13 relapses, the last occurring a median of 16 months (2–26 months) after initial treatment. Thus patients with imported gnathostomiasis should be monitored for at least 6 months to detect late treatment failure.

Geophagy, the regular and deliberate consumption of soil, is prevalent among pregnant women in sub-Saharan Africa. We examined the associations of geophagy with anemia and helminth infection among 971 human immunodeficiency virus (HIV)-positive pregnant women in Tanzania. About 29% of pregnant women regularly consumed soil. Occupation, marital status, and gestational age were associated with geophagy. Ascaris lumbricoides infection was associated with the prevalence of geophagy (adjusted-prevalence ratio 1.81; 95% confidence interval [CI] = 1.37–2.40); however, hookworm, Trichuris trichiura, and Strongyloides stercoralis showed no association. Anemia and red blood cell characteristics suggestive of iron deficiency were strongly correlated with geophagy at baseline. In longitudinal analyses, we found evidence suggesting that soil consumption may be associated with an increased risk of anemia (adjusted-relative risk 1.16; 95% CI = 0.98–1.36) and a lower hemoglobin concentration (adjusted-mean difference −3.8 g/L; 95% CI [−7.3, −0.4]). Pregnant women should be informed about the potential risks associated with soil consumption.

Concurrent ingestion of microfilariae (mf) and arboviruses by mosquitoes can enhance the transmission of virus compared with when virus is ingested alone. We studied the effect of mf enhancement on the extrinsic incubation period (EIP) of dengue 1 virus within Aedes aegypti mosquitoes by feeding mosquitoes on blood that either contained virus plus Brugia malayi mf or virus only. Mosquitoes were sampled over time to determine viral dissemination rates. Co-ingestion of mf and virus reduced viral EIP by over half. We used the computer simulation program, DENSiM, to compare the predicted patterns of dengue incidence that would result from such a shortened EIP versus the EIP derived from the control (i.e., virus only) group of mosquitoes. Results indicated that, over the 14-year simulation period, mf-induced acceleration of the EIP would generate more frequent (but not necessarily more severe) epidemics. Potential interactions between arboviruses and hematozoans deserve closer scrutiny.

The present work deals with the identification of a patient with two liver abscesses containing two different strains of Entamoeba histolytica, as defined by chitinase gene plymorphisms.

A superoxide dismutase excreted by promastigote forms of L. (Viannia) peruviana (SODe-Lp), L. (Viannia) brazilensis (SODe-Lb), and L. (L.) amazonensis (SODe-La) is tested to evaluate its potential value as a diagnostic tool of mucocutaneous and Andean cutaneous leishmaniasis. We used 45 sera with mucocutaneous leishmaniasis (SL) and 68 with Andean cutaneous leishmaniasis (ACL). SODe-Lp antigen was recognized by 94% of the serum from ACL patients, and the SODe-Lb antigen was recognized by 93% of the serum from SL patients. Meanwhile, the result for SL and ACL patients with SODe-La antigen was 69% and 43% and SODe-Li was 11% and 9%, respectively. This suggest that antibodies to SODe-Lp undergo further response in patients with ACL and the antibodies to SODe-Lb do so preferentially in patients with SL. The SODe ELISA may be useful in endemic areas for discriminative assays between patients with different forms of leishmaniases and those with other clinical conditions.

We describe microneutralization assays that used automated 96-well enzyme-linked immunospot (ELI-SPOT) readout instrumentation to measure human anti-dengue virus (DENV) antibodies in CV-1 cells that were stably transfected to express human FcγRIIA (CD32) using conventional Vero cells as a comparator. Classic plaque reduction neutralization test (PRNT) end-point titers were determined by probit analysis. Neutralization titers against DENV measured in CV-1 transfectants were expressed in terms of both conventional 50% to 90% PRNT end-point titers and differential infectivity of antibody-treated virus in control and CD32-expressing CV-1 cells. Significantly reduced PRNT titers and strikingly heightened infectivity (up to 100-fold) of antibody-treated DENV was observed in CV-1 CD32 transfectants compared with that observed in control CV-1 or Vero cells. Because DENVs may preferentially replicate in CD32-expressing monocytes/macrophages and dendritic cells, in vivo, it is possible that CD32 introduced into a conventional DENV neutralization assay might provide results that better correlate with protection.

The 2005 dengue outbreak in Singapore cumulated in > 14,000 cases and 27 reported dengue deaths. We fit the single-phase Richards model to weekly dengue notification numbers to detect the turning point for the outbreak, which enables us to study the impact of intervention measures relating to the turning point. The results indicate that turning point had most likely occurred in late August or early September, before large-scale intervention measures were implemented. The “initial” reproduction number for the outbreak is estimated to be ~1.89–2.23 (95% confidence interval: 1.15–3.00). One of the lessons learned from the 2003 severe acute respiratory syndrome (SARS) outbreak is that multiple phases of outbreak were observed in some affected countries when efforts to intensify intervention or to sustain vigilance were compromised. Intensive and continuing efforts in the implementation of control measures are essential in reducing further dengue occurrences during any resurgence of dengue.

Rocky Mountain spotted fever (RMSF) occurs throughout much of the United States, ranging in clinical severity from moderate to fatal infection. Yet, little is known about possible differences among severity levels across geographic locations. To identify significant spatial clusters of severe and non-severe disease, RMSF cases reported to Centers for Disease Control and Prevention (CDC) were geocoded by county and classified by severity level. The statistical software program SaTScan was used to detect significant spatial clusters. Of 4,533 RMSF cases reported, 1,089 hospitalizations (168 with complications) and 23 deaths occurred. Significant clusters of 6 deaths (P = 0.05, RR = 11.4) and 19 hospitalizations with complications (P = 0.02, RR = 3.45) were detected in southwestern Tennessee. Two geographic areas were identified in north-central North Carolina with unusually low rates of severity (P = 0.001, RR = 0.62 and P = 0.001, RR = 0.45, respectively). Of all hospitalizations, 20% were clustered in central Oklahoma (P = 0.02, RR = 1.43). Significant geographic differences in severity were observed, suggesting that biologic and/or anthropogenic factors may be impacting RMSF epidemiology in the United States.

An investigation into the risk of occupationally acquired melioidosis at a mine site in northern Australia found that 45 (13%) of 345 staff had serologic evidence of exposure and 14 (4%) had recent exposure to Burkholderia pseudomallei or closely related bacteria. There was only one culture-confirmed case of melioidosis in mine staff during the study period. The lack of overt infection directly attributable to work activities despite detectable B. pseudomallei on site, the absence of an association between positive serology and occupational activity on site, or duration of employment in the mining industry stand against a significant occupationally acquired infection risk on this industrial site. Workplace exposure to a dust-generating tropical environment in the melioidosis-endemic north of Australia did not appear to pose a measurable increase in infection risk. The effect of long-term climatic trends on this potential biologic threat requires further study.

As part of our ongoing surveillance efforts for West Nile virus (WNV) in the Yucatan Peninsula of Mexico, 96,687 mosquitoes collected from January through December 2007 were assayed by virus isolation in mammalian cells. Three mosquito pools caused cytopathic effect. Two isolates were orthobunyaviruses (Cache Valley virus and Kairi virus) and the identity of the third infectious agent was not determined. A subset of mosquitoes was also tested by reverse transcription–polymerase chain reaction (RT-PCR) using WNV-, flavivirus-, alphavirus-, and orthobunyavirus-specific primers. A total of 7,009 Culex quinquefasciatus in 210 pools were analyzed. Flavivirus RNA was detected in 146 (70%) pools, and all PCR products were sequenced. The nucleotide sequence of one PCR product was most closely related (71–73% identity) with homologous regions of several other flaviviruses, including WNV, St. Louis encephalitis virus, and Ilheus virus. These data suggest that a novel flavivirus (tentatively named T’Ho virus) is present in Mexico. The other 145 PCR products correspond to Culex flavivirus, an insect-specific flavivirus first isolated in Japan in 2003. Culex flavivirus was isolated in mosquito cells from approximately one in four homogenates tested. The genomic sequence of one isolate was determined. Surprisingly, heterogeneous sequences were identified at the distal end of the 5′ untranslated region.

Continued Nipah encephalitis outbreaks in Bangladesh highlight the need for preventative and control measures to reduce transmission from bats to humans and human-to-human spread. Qualitative research was conducted at the end of an encephalitis outbreak in Faridpur, Bangladesh in May 2004 and continued through December 2004. Methods included in-depth interviews with caretakers of cases, case survivors, neighbors of cases, and health providers. Results show contrasts between local and biomedical views on causal explanations and appropriate care. Social norms demanded that family members maintain physical contact with sick patients, potentially increasing the risk of human-to-human transmission. Initial treatment strategies by community members involved home remedies, and public health officials encouraged patient hospitalization. Over time, communities linked the outbreak to supernatural powers and sought care with spiritual healers. Differing popular and medical views of illness caused conflict and rejection of biomedical recommendations. Future investigators should consider local perceptions of disease and treatment when developing outbreak strategies.

Multilevel analysis was used to identify individual and household level factors associated with malaria risk in 1,367 individuals in a peri-urban area of highland Ethiopia. Living within 450 m of a major vector-breeding site accounted for 38.78% and 78.49% of between-household variance in malaria incidence in adults and children, respectively. In adults, other individual level factors associated with malaria risk were regular or recent travel to rural areas (incidence rate ratio [IRR] = 12.96; 95% confidence interval [CI] = 4.05, 41.48) and having an indoor job (IRR = 0.37; 95% CI = 0.16, 0.87). Household level factors associated with adult malaria risk were low vegetation level in compound (IRR = 0.27; 95% CI = 0.10, 0.78), tidy compound (IRR = 0.29; 95% CI = 0.12, 0.71), household use of preventive measures (IRR = 0.31; 95% CI = 0.13, 0.74), and the number of 5- to 9-year-old children in the household (IRR = 1.66; 95% CI = 1.08, 2.53). Aside from distance to the vector-breeding site, few other malaria risk factors were identified in children. Malaria interventions in highland African communities should address household level factors associated with malaria clustering.