The American Journal of Tropical Medicine and Hygiene - Volume 72, Issue 4, 2005

Although primary hyperparathyroidism and malignant diseases account for approximately 90% of the causes of hypercalcemia, they could occur in association with granulomatous diseases such as tuberculosis or sarcoidosis, especially in developing countries. Hepatic tuberculosis is difficult to diagnosis without suspicion in cases with normal findings on chest radiographs. We report a 70-year-old woman who presented with hypercalcemia due to hepatic tuberculosis. The diagnosis was made by a computed tomography scan and laparoscopic evaluation. After treatment with anti-tuberculosis medication, her hypercalcemia resolved. Increased vitamin D synthesis by activated macrophages in the granuloma tissue is the major mechanism of hypercalcemia in tuberculosis.

The association between sex, nutritional status, and the severity of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), and immune status was investigated in 245 Vietnamese infants with predominantly primary infections with dengue virus. Male and female infants were at equal risk of developing DHF/DSS. However, infants of low height and weight for age were under-represented among DHF/DSS cases compared with 533 healthy baby clinic infant controls. Acute illness phase blood levels of selected cytokines (interferon-γ and tumor necrosis factor-α) and serum levels of antibodies to dengue virus were elevated in the same range in male and female infants with DHF/DSS, as well as in infants with and without malnutrition.

The binding of dengue type 2 (DEN-2) virus to mammalian (LLC-MK2 and Vero) and mosquito (C6/36 and AP61) cell surfaces was investigated by a virus-binding assay using purified 3H-labeled DEN-2 virus. The DEN-2 virus binding to all four cell types was specific and saturable, indicating the presence of a single class of receptors (ranging from 3.7 × 103 to 3.5 × 104 receptors/cell) with a high affinity for DEN-2 virus (K d ranging from 98 to 171 pM). Treatment of cell surfaces with certain glycosidases significantly reduced virus binding to mammalian cell lines, but not to the insect cell lines examined. Furthermore, heparin was found to compete with mammalian cell receptors for binding to DEN-2 virus and to inhibit viral infection of mammalian cells, but heparin had no effect on viral binding to or infection of insect cells. These results confirm previous reports suggesting that DEN-2 virus receptors on mammalian cell lines are different from those on insect cell lines.

Information on hookworm infection and re-infection in a cohort of primary school children and interview data on their socioeconomic background and behavior were combined with environmental data using a geographic information system (GIS). Multivariate models served to explore the covariation of environmental and infection patterns adjusted for possible confounders. Our aim was to identify environmental factors that might serve to predict infection and thus guide control efforts when epidemiologic information is insufficient. Furthermore, we wanted to establish whether soil type has a genuine influence on hookworm infection. Prevalence maps and spatial statistics showed considerable spatial clustering of infection in the small (∼28 × 16 km) study area. The multivariate logistic regression models showed strong positive associations of infection at baseline (baseline prevalence = 83.2%) with settlement density (odds ratio [OR] = 1.24, 95% confidence interval [CI] = 1.10–1.38) and vegetation density (OR = 1.66, 95% CI = 1.25–2.22) and a strong negative association with the clay content of the soil (OR = 0.67, 95% CI = 0.62–0.73). Similar but weaker correlations were found after re-infection. Socioeconomic status and behavior did not seem to confound these associations. Spatial analysis of the model residuals suggested that because the models accounted for most of the spatial pattern, the model standard errors were not affected by spatial clustering. Our study shows that the pattern of hookworm infection is strongly influenced by several environmental factors. The GIS-aided prediction of areas in need of treatment is therefore a promising tool to guide control efforts when epidemiologic information is insufficient.

Human-made ecologic transformations have occurred at an unprecedented rate over the past 50 years. Prominent among them are water resource development projects. An estimated 40,000 large dams and 800,000 small dams have been built, and 272 million hectares of land are currently under irrigation worldwide. The establishment and operation of water projects has had a history of facilitating a change in the frequency and transmission dynamics of malaria, but analyses of these environmental risk factors are sparse. Here, we present a comprehensive review of studies that assessed the impact of irrigation and dam building on malaria prevalence or incidence, stratified by the World Health Organization’s (WHO) sub-regions of the world, and link these studies with the latest statistics on disability adjusted life years, irrigated agriculture, and large dams. We also present estimates of the population at risk due to proximity to irrigation schemes and large dam reservoirs. In WHO sub-regions 1 and 2, which have 87.9% of the current global malaria burden, only 9.4 million people are estimated to live near large dams and irrigation schemes. In contrast, the remaining sub-regions concentrate an estimated 15.3 million people near large dams and up to 845 million near irrigation sites, while here only 12.1% of the global malaria burden is concentrated. Whether an individual water project triggers an increase in malaria transmission depends on the contextual determinants of malaria, including the epidemiologic setting, socioeconomic factors, vector management, and health seeking behavior. We conclude that in unstable malaria endemic areas, integrated malaria control measures, coupled with sound water management, are mandatory to mitigate the current burden of malaria in locations near irrigation or dam sites.

The importation of drug-resistant malaria is a growing public health problem in non-endemic countries. The combination of atovaquone and proguanil (Malarone™) has become established as an agent of choice to prevent and treat chloroquine-resistant Plasmodium falciparum malaria in travelers. We describe the first reported case in North America of genetically confirmed atovaquone/proguanil-resistant P. falciparum malaria. Polymerase chain reaction and sequence analysis of the primary and recrudescent isolates confirmed the acquisition of a point mutation (Tyr268Ser) in the cytochrome b gene of the recrudescent isolate known to confer high-level resistance to atovaquone. Suboptimal therapy may have played a contributory role in the emergence of resistance.

The use of chloroquine treatment for Plasmodium falciparum malaria was abandoned in China in 1979 because of widespread drug resistance. Subsequent studies found decreases in the prevalence of chloroquine-resistant strains. To evaluate these decreases and assess the current status of chloroquine sensitivity in Hainan, China, we determined the prevalence of the P. falciparum chloroquine resistance transporter (PfCRT) 76T marker in the DNA of blood samples collected from 1978 to 2001. Results showed the presence of PfCRT 76T in 101 of 112 samples (90%) from 1978 to 1981, 30 of 43 samples (70%) from 1986, 22 of 34 samples (65%) from 1997 to 1998, and 37 of 68 samples (54%) from 2001. The prevalence of PfCRT 76T thus progressively decreased after chloroquine was discontinued as a treatment for P. falciparum malaria (χ2 = 5.2, P < 0.022 [1978–1981 versus 1986]; χ2 = 7.4, P < 0.006 [1978–1981 versus 1997–1998]; and χ2 = 28.8, P < 0.0001 [1978–1981 versus 2001]). Reduced prevalence of the PfCRT 76T marker is consistent with greater rates of chloroquine sensitivity from in vitro drug assays of blood samples in 1997 and 2001. Monitoring for continued decreases will provide valuable information for future drug-use policies in China.

We evaluated the use of 7SL RNA gene sequences for the identification of Leishmania spp. A fragment (~137 basepairs) of the 7SL RNA gene from 13 reference strains and 18 clinical isolates of 11 different Leishmania species was amplified and sequenced using conserved primers. Reference strains from each Leishmania spp. complex showed unique sequences. The nucleotide sequences were compared pairwise and a range of 81.0–99.3% intercomplex similarity was observed. Clinical isolates of the same species had sequences identical to the corresponding reference strains; thus, the intraspecies similarity was 100%. A phylogenetic tree derived from the 7SL RNA gene partial sequences was constructed and is in agreement with accepted phylogenetic schemes.

Two hundred twenty-six consecutive adult patients with cutaneous leishmaniasis in Colombia were treated with Glucantime and 81% were cured. The 19% who failed treatment had received a statistically significant lower total amount of antimony (354 mg/kg) than those who were cured (405 mg/kg) (P = 0.002). Thirty-nine of the failures were re-treated with Glucantime and 59% were cured. This large experience on initial and re-treatment cure rates probably represents the values found in clinical practice. In this series, parasite resistance may have been induced by the relatively low initial dose of antimony administered to some patients.

We evaluated the Leishmania Viannia-specific primers B1-B2 to detect Leishmania in normal skin and peripheral blood monocytes of patients with active cutaneous leishmaniasis. Southern blotting and sequencing of polymerase chain reaction (PCR) products confirmed the specificity of kinetoplast DNA (kDNA) amplification from tissue fluid from healthy skin, whereas the PCR with monocytes also amplified a human sequence of a size similar (718 basepairs) to the expected kDNA product (750 basepairs), resulting in false-positive results. Although B1 was not homologous to any human DNA sequence, B2 showed homology to a human chromosome 2 intergenic region (AC010878) at positions 35,881-36,599, which are spaced 718 nucleotides apart. Amplification of the human art3fact from monocyte DNA was confirmed using the primer B2 alone. Examination of other primers reported for the PCR of kDNA from various species of Leishmania showed that six of seven were homologous to human DNA sequences. These findings underscore the importance of exploiting sequencing, bioinformatics, and DNA probes to refine molecular amplification techniques and to validate the performance of primers when used for new applications.

The Global Program to Eliminate Lymphatic Filariasis (GPELF), which includes alleviation of disability and suffering of patients, is run primarily in India by the primary health care system. The present study assessed the knowledge and practices related to lymphedema care among peripheral health workers of the primary health care system in a filarial-endemic district of Orissa, India. A total of 41 health workers sampled across the district were subjected to in-depth interviews. The results showed that many lymphedema patients visit the peripheral health institutions mostly for the treatment of acute episodes of lymphangitis. Many health workers do not know the concept of foot care and its importance in lymphedema management. However, a few health workers advised the patients to follow some components of foot care. The knowledge levels and practices of peripheral health workers are not at desirable levels. The medical and paramedical staff of the peripheral health institutions should be oriented about the management of lymphedema and peripheral health workers should promote the foot care practices. For the GPELF as a whole to prove successful, the patients who already have lymphedema need to be cared for and have their morbidity relieved as much as possible.

A hierarchical population genetic study was conducted among 19 Aedes aegypti populations in Thailand from Chiang Mai in the north to Songkhla province in the south. Single-strand conformation polymorphism analysis was used to examine variation in a 359-basepair region of the NADH dehydrogenase subunit 4 mitochondrial DNA gene (ND4). Seven haplotypes were detected in two lineages previously identified in ND4 haplotypes from North America. Gene flow estimates and highly significant variation among populations within 25 kilometers implicated genetic drift and vector control efforts as major factors in genetic structure. Mantel regression analysis demonstrated no isolation by distance. Urban areas were relatively panmictic, while suburban/rural sites exhibited more restricted gene flow. Significant genetic structure among groups of collections > 100 kilometers apart is consistent with recent (~50 year) expansion of Ae. aegypti from highly populated areas accompanied by founder effects, but could also reflect the overall low genetic diversity in ND4 in Thailand.

An intervention study was implemented on five Indonesian islands highly endemic for leprosy to determine whether rifampicin can be used as chemoprophylaxis to prevent leprosy. The population was actively screened before the intervention and subsequently once a year for three years. In the control group, no chemoprophylaxis was given. In the contact group, chemoprophylaxis was only given to contacts of leprosy patients and in the blanket group to all eligible persons. The cohort consisted of 3,965 persons. The yearly incidence rate in the control group was 39/10,000; the cumulative incidence after three years was significantly lower in the blanket group (P = 0.031). No difference was found between the contact and the control groups (P = 0.93). Whether this apparent reduced leprosy incidence in the first three years in the blanket group is due to a delayed development of leprosy or a complete clearance of infection needs to be determined.

The reliability and validity of the earlier developed Buruli ulcer functional limitation score (BUFLS) questionnaire was assessed. Of 638 former Buruli ulcer patients (of 678 individuals examined), sufficient items on daily activities (≥ 13 of the 19) were applicable to calculate a score. To determine the validity, the functional limitation scores of the 638 individuals were compared with the global impression of the limitations, range of motion (ROM), and the social impact (change of occupation or education) of Buruli ulcer. To determine inter-observer reliability, the functional limitation score was reassessed in 107 participants within one and three weeks after the first interview by another interviewer and interpreter. Both global impression and ROM correlated well with the functional limitation scores (ρ = 0.66 and ρ = 0.61). The inter-observer reliability of 107 participants as measured by an intra-class correlation coefficient of 0.86 was very good. The functional limitation scores measured in the second assessment were significantly higher than in the first assessment. This should be taken into account when the functional limitation score is used for the individual patient. The BUFLS can be used as for between group comparisons of endpoints in clinical trials and in the planning of resources.

Bartonella henselae, an emerging pathogen bacterium, is the main causative agent of the cat scratch disease. While the first clinical descriptions were associated with immunosupressed patients, it is now more frequently observed in patients with normal immune status (endocarditis and bacteremia). Cats were found to be the only known reservoir of B. henselae. In this paper, we report the results obtained in the first study made to investigate the prevalence of B. henselae bacteremia and antibodies in domestic cats in Catalonia, Spain. Serum samples from 115 cats were tested for antibodies to B. henselae by immunofluorescent antibody testing, and 29.6% had a titer ≥ 1:64. Seven B. henselae strains were isolated using standard culture techniques and amplification by a polymerase chain reaction and subsequent sequencing was performed on the intergenic spacer region between the 16 and 23S ribosomal RNA genes. Of all factors concerning the studied bacteremia rate (age, sex, habitat, presence of antibodies, contact with animals, parasites), only the presence of antibodies to B. henselae was statistically significant.

A partial gene sequence encoding the 56-kD scrub typhus antigen (Sta56) was amplified from genomic DNA of the Orientia tsutsugamushi Karp strain by a polymerase chain reaction (PCR). The PCR product was ligated with the 47-kD scrub typhus antigen (Sta47) gene in the pQE30/47 expression vector, and the resulting recombinant expression vector was designated pQE30/56-47. A fusion antigen (Sta56-47) was expressed in Escherichia coli cells transformed with pQE30/56-47 after induction with isopropyl-β-d-thiogalactopyranoside. The Sta56-47 antigen was recognized by both Sta47 and Sta56 immune sera and by immune serum to Sta56-47 in an immunoblot assay. This antigen was purified and used to immunize BALB/c mice. The animals immunized with Sta56-47 exhibited profound humoral and cellular immune responses, as well as increased resistance to O. tsutsugamushi Karp compared with mice immunized with Sta56 or Sta47. These results strongly suggest that Sta56-47 contains antigenic epitopes of the Sta56 and Sta47 antigens of O. tsutsugamushi Karp, and is a more suitable candidate for replacing whole-cell antigen of O. tsutsugamushi Karp to induce protective immunity against scrub typhus.

Thai patients with scrub typhus caused by the intracellular pathogen Orientia tsutsugamushi displayed elevated plasma concentrations of granzymes A and B, interferon-γ (IFN)-γ–inducible protein 10, and monokine induced by IFN-γ. These data suggest that activation of cytotoxic lymphocytes is part of the early host response to scrub typhus.

The World Health Organization currently recommends annual mass antibiotic treatment to eliminate the ocular chlamydia that cause blinding trachoma. Active trachoma is believed to be seasonal in many areas of the world, and the optimal season in which to treat has not as yet been established. Here we use mathematical models of disease transmission to demonstrate that ideally, treatment should be administered before the low season to have the greatest chance of locally eliminating infection.

A 25-year-old woman, later identified as index case of Crimean-Congo hemorrhagic fever (CCHF), presented to Holy Family Hospital in Rawalpindi, Pakistan with fever and generalized coagulopathy. A retrospective contact tracing was conducted to explore the modes of exposure possibly associated with transmission of CCHF infection among contacts. We traced 32 contacts of the index case and 158 contacts of secondary cases and tested them for IgG and IgM antibodies against CCHF virus by an enzyme-linked immunosorbent assay technique. According to the type of exposure, contacts were divided into five subsets: percutaneous contact with blood, blood contact to unbroken skin, cutaneous contact to non-sanguineous body fluids, physical contact with patients without body fluids contact, and close proximity without touching. Two out of four contacts who reported percutaneous exposure tested positive for antibodies to CCHF virus. We conclude that simple barrier methods and care in provision of CCHF cases may prevent transmission of this infection.

Samples of laboratory propagated Venezuelan equine encephalitis (VEE), West Nile (WN), and yellow fever (YF) viruses were blotted onto filter paper discs, air-dried, and stored at room temperature. At regular intervals over a 90-day period, the dried virus samples were eluted, tested for infectivity by culture and titration in Vero cells, and examined for viral RNA by a reverse transcriptase–polymerase chain reaction. The VEE, WN, and YF viral RNA was detected throughout the 90-day period in all samples examined. Infectious VEE virus could be recovered for up to 40 days; WN and YF viruses were cultured in Vero cells for up to 60 and 90 days, respectively. The results of this study demonstrate that viral nucleic acids and infectious virus can be recovered from arbovirus samples air-dried on filter paper and stored at room temperature for a month or more after collection. This procedure offers a simple and inexpensive method for collecting arbovirus field specimens and transporting them to diagnostic laboratories.

Neurologic complications in the course of Plasmodium falciparum infections are commonly diagnosed as cerebral malaria, but bacterial or viral meningitis may exhibit similar symptoms. One to three weeks after P. falciparum malaria, acute disseminated encephalomyelitis (ADEM) can also mimick the symptoms of cerebral malaria. We describe a 31-year-old woman with life-threatening ADEM five days after successful treatment of P. falciparum malaria. The detection of IgG and IgM antibodies in serum and cerebrospinal fluid (CSF) against multiple viruses and bacteria reflected a non-specific polyclonal B cell activation and was more confusing than helpful for diagnostic decisions. Varicella zoster virus was identified with a reverse transcriptase multiplex polymerase chain reaction in the initially obtained and frozen CSF. This case and findings from the literature indicate that P. falciparum-associated ADEM might not be immune mediated, but of infectious origin. With unclear cerebral complications during or after P. falciparum malaria, prompt initiation of empirical antiviral and antibacterial treatment in addition to antimalarials may reduce mortality.

The arboviral surveillance program in California depends in part on sentinel chickens to detect western equine encephalomyelitis virus, St. Louis encephalitis virus, and West Nile virus activity. From 2000 through 2002, 1,578 serum specimens from 34 sentinel flocks in northern and southern California were tested for antibodies to Culex tarsalis salivary gland antigens. Sentinel chickens that were seropositive for mosquito salivary gland antigens were more likely to seroconvert to St. Louis encephalitis virus than those seronegative for salivary gland antigens. Flocks with mosquito traps located < 50 feet away had a reduced antibody response to mosquito salivary gland antigens. The use of sentinel chickens and mosquito traps for arboviral surveillance should be standardized to ensure that surveillance data from different sites are comparable and that flocks have comparable opportunities for mosquito exposure. Sentinel chickens should be accessible to potential mosquito vectors to maximize their sensitivity for detecting arboviral activity.

An outbreak of acute diarrheal disease was reported in Kupang, Nusa Tenggara, Indonesia, in August 2002. An investigative team carried out a retrospective historical review of records, and a case-control study involving data and specimen collections. Etiologic determination involving stool specimens was based on an enzyme-linked immunosorbent assay, with a reverse transcriptase–polymerase chain reaction performed for serotyping purposes. Two thousand six hundred probable cases were identified from hospital records during the outbreak months of June, July, August, and September 2002. Previous enteric outbreaks were recognized from the same months in the preceding years and all annual outbreak episodes following a period of prolonged, low rainfall. In contrast to previous outbreaks discerned from trend analysis, the overwhelming burden of disease fell upon the pediatric population versus the young and old in previous outbreak instances. Rotavirus was found to be the causative etiology, with serotype 1 predominating.

A cohort study involving 60 human immunodeficiency virus (HIV)-negative male transvestite commercial sex workers (CSWs) was conducted in Montevideo, Uruguay in 1999–2001. Serum samples were tested for HIV by an enzyme-linked immunosorbent assay screening with immunoblot confirmation. Six participants seroconverted for an incidence-density rate of 6.03 (95% confidence interval = 2.21–13.12) per 100 person-years. Inconsistent condom use during client sex (adjusted hazard ratio [AHR] = 6.7), during oral sex (AHR = 5.6), and at the last sexual encounter (AHR = 7.8), and use of marihuana (AHR = 5.4) were marginally associated with HIV seroconversion. Five samples were genotyped in the protease and reverse transcriptase regions; three were subtypes B and two were BF recombinants. Full genome analysis of four samples confirmed all three subtype B samples and one of the two BF recombinants. Male transvestite CSWs sustained a high rate of HIV infection. Larger prospective studies are required to better define subtypes and associated sexual and drug-related risk factors.