The American Journal of Tropical Medicine and Hygiene - Volume 85, Issue 3, 2011

Global commerce, travel, and emerging and resurging infectious diseases have increased awareness of global health threats and opportunities for collaborative and service learning. We review course materials, knowledge archives, data management archives, and student evaluations for the first 10 years of an intensive summer field course in infectious disease epidemiology and surveillance offered in Jamaica. We have trained 300 students from 28 countries through collaboration between the University of the West Indies and U.S. partner universities. Participants were primarily graduate students in public health, but also included health professionals with terminal degrees, and public health nurses and inspectors. Strong institutional synergies, committed faculty, an emphasis on scientific and cultural competencies, and use of team-based field research projects culminate in a unique training environment that provides participants with career-developing experiences. We share lessons learned over the past decade, and conclude that South-to-North leadership is critical in shaping transdisciplinary, cross-cultural, global health practice.

Lack of global health knowledge places immigrants at risk of iatrogenic morbidity. Although global health education programs have grown in popularity, measurable impact is lacking. We previously surveyed 363 physicians in training across 15 programs in four countries in 2004 regarding basic parasite knowledge and recognition of Strongyloides risk through a theoretical case scenario. In 2005, the University of Minnesota implemented a formal global health training program (GHP). In 2009, the identical survey was repeated. Strongyloidiasis recognition increased from 11.1% (19/171) in 2004 to 39.4% (50/127) in 2009 (P < 0.001). Trainees participating in formal didactic and interactive curriculum had superior recognition (77% versus 29%; P < 0.001). In a multivariate model of GHP training activities, participation in an American Society of Tropical Medicine and Hygiene-accredited global health certificate course increased recognition (odds ratio = 9.5, 95% confidence interval = 2.5–36, P = 0.001), whereas participation in international electives alone did not (P = 0.9). A formal GHP curriculum was associated with improved knowledge regarding common parasitic infections and the risk of iatrogenic morbidity and mortality due to strongyloidiasis.

During 1991–2010, 456 persons from 62 countries were provided financial support to attend the annual meeting of the American Society of Tropical Medicine and Hygiene. Winners came from 17 African, 16 Asia-Pacific, 14 Latin American and Caribbean, and 13 European and Middle Eastern countries, and from Canada and the United States. Virtually equal numbers of awards were offered to women and men. Winners were selected from U.S. academic centers (30%), foreign universities (26%), international centers, institutes or research units (30%), and approximately 5% from U.S. government agencies. Almost all winners (73 of 76, 96%) had scientific publications subsequent to receiving the travel award. Less than 10% of award winners continued their membership in the Society after their one-year complementary membership. Winners indicated that the travel awards program facilitated international exchange and fostered collaborations between Society members and international scientists.

We studied the prevalence of anemia during pregnancy and its relationship with low birth weight (LBW; birth weight < 2,500 g) in Benin. We analyzed 1,508 observations from a randomized controlled trial conducted from 2005 to 2008 showing equivalence on the risk of LBW between two drugs for Intermittent Preventive Treatment of malaria during pregnancy (IPTp). Despite IPTp, helminth prophylaxis, and iron and folic acid supplementations, the proportions of women with severe anemia (hemoglobin [Hb] concentration < 80 g/L) and anemia (Hb < 110 g/L) were high throughout pregnancy: 3.9% and 64.7% during the second and 3.7% and 64.1% during the third trimester, but 2.5% and 39.6% at the onset of labor, respectively. Compared with women without anemia (Hb ≥ 110 g/L) during the third trimester, women with severe anemia (Hb < 80 g/L) were at higher risk of LBW after adjustment for potential confounding factors (prevalence ratio [PR] = 2.8; 95% confidence interval [1.4–5.6]).

Eastern equine encephalitis virus (EEEV) is endemic throughout most of the eastern United States. Although it is transmitted year round in Florida, transmission elsewhere is seasonal. The mechanism that enables EEEV to overwinter in seasonal foci remains obscure. In previous field studies, early season EEEV activity was detected in mosquito species that feed primarily upon ectothermic hosts, suggesting that reptiles and amphibians might represent overwintering reservoir hosts for EEEV. To determine if this might be possible, two commonly fed upon amphibian and reptile species were evaluated as hosts for the North American subtype I strain of EEEV. Neither amphibian species was a competent host. However, circulating viremias were detected in both reptile species examined. Hibernating infected garter snakes remained viremic after exiting hibernation. These data suggest that snakes may represent an overwintering host for North American EEEV.

The mosquito-transmitted pathogen West Nile virus (WNV) is not yet present in the Galápagos Archipelago of Ecuador. However, concern exists for fragile endemic island fauna after population decreases in several North American bird species and pathology in certain reptiles. We examined WNV vector competency of a Galápagos strain of mosquito (Culex quinquefasciatus Say). Field specimens were tested for their capacity to transmit the WN02-1956 strain of WNV after incubation at 27°C or 30°C. Rates of infection, dissemination, and transmission all increased with days post-exposure to WNV, and the highest rates were observed at 28 days. Infection rates peaked at 59% and transmission rates peaked at 44% (of mosquitoes tested). Vector efficiency increased after day 14. Rates of infection but not of transmission were significantly influence by temperature. No vertical transmission was detectable. We demonstrate that Galápagos Cx. quinquefasciatus are competent WNV vectors, and therefore should be considered an animal and public health risk for the islands and controlled wherever possible.

Mosquitoes in the Culex pipiens complex are important vectors of several disease-causing pathogens, including West Nile virus. In North America, the complex consists of Cx. pipiens pipiens form pipiens, Cx. pipiens pipiens form molestus, Cx. pipiens quinquefasciatus, and their hybrids that exhibit substantial diversity in physiology, behavior, and geographic range. Hybridization among these mosquitoes is of concern because of potential implications for disease transmission. Currently, several morphological and molecular markers exist for differentiating members of the Cx. pipiens complex; however, these markers have specific limitations. We report here two highly reliable ribosomal DNA-based single nucleotide polymorphism (SNP) markers, CxpG2T and CxpA2d, for detecting Cx. pipiens complex mosquitoes containing Cx. p. quinquefasciatus alleles. Both CxpG2T and CxpA2d contain one allele that is present in all members of the Cx. pipiens complex, and the other allele is specific to Cx. p. quinquefasciatus. Testing of field populations from the eastern United States showed that these two SNP markers are capable of identifying a south to north gradient of Cx. p. quinquefasciatus and hybrids. The northern limit of detection of Cx. p. quinquefasciatus alleles in this study was in Fort Totten, NY (40.79°N), whereas the southern boundary was determined between Atlanta, GA (33.81°N) and Gainesville, FL (29.64°N). CxpG2T and CxpA2d were more accurate than the ACE-2 marker, and they may conceivably provide comparable resolution with microsatellite markers for detecting Cx. p. quinquefasciatus alleles.

Tahyna virus (TAHV) is widely distributed in Europe and Asia. A previous study reported a high level of conservation of the TAHV genome in isolates from Europe. During 2006 and 2007, three Tahyna virus isolates from mosquitoes were obtained from various locations in Xinjiang, People's Republic of China. We analyzed the complete coding sequence of full-length small, medium, and large segments of these isolates. Molecular and phylogenetic analyses of the three complete TAHV genomes showed that sequence identity between isolates from China and Europe was more divergent, and an unexpected level of medium segment diversity was found among isolates from China compared with high levels of sequence conservation for the small and large segments. This study indicated that effects of genotypic diversity on the ecology, transmission, and pathogenicity of TAHV in China should be studied.

The vector competence of Australian mosquitoes for yellow fever virus (YFV) was evaluated. Infection and transmission rates in Cairns and Townsville populations of Aedes aegypti and a Brisbane strain of Ae. notoscriptus were not significantly different from a well-characterized YFV-susceptible strain of Ae. aegypti. After exposure to 107.2 tissue culture infectious dose (TCID50)/mL of an African strain of YFV, > 70% of Ae. aegypti and Ae. notoscriptus became infected, and > 50% transmitted the virus. When exposed to 106.7 TCID50/mL of a South American strain of YFV, the highest infection (64%) and transmission (56%) rates were observed in Ae. notoscriptus. The infection and transmission rates in the Cairns Ae. aegypti were both 24%, and they were 36% and 28%, respectively, for the Townsville population. Because competent vectors are present, the limited number of travelers from endemic areas and strict vaccination requirements will influence whether YFV transmission occurs in Australia.

We reviewed the records of 446 patients who were treated surgically for cystic echinococcosis (CE) to identify risk factors for anaphylactic shock. Of 446 patients, 10 had final diagnoses of anaphylactic shock induced by CE; none died. The incidence of anaphylactic shock was significantly higher in younger age groups (P < 0.001) and in patients with pulmonary cysts. Anaphylactic shock induced by CE appears to differ from type I immediate hypersensitivity shock, which suggests that in CE, shock may be caused by a combination of immediate hypersensitivity and endotoxic shock. This possibility suggests that additional precautions should be taken during surgery. These precautions include reducing intracystic pressure, which would prevent possible leaked liquid from reaching other organs by surrounding the cyst with sterile gauze and decrease the chance of spreading the echinococcus; preventing antigen from contacting other tissues where it might trigger anaphylaxis; and resecting the cyst completely when feasible.

We herein report a case of a young Japanese female who was confirmed to have cystic echinococcosis (CE) 1 stage based on the World Health Organization Informal Working Group on Echinococcosis pathological classification of CE, and she was also suspected to be infected with eggs of the G1 Echinococcus granulosus sensu stricto during her stay in the United Kingdom and therefore, suffered from synchronous pulmonary and hepatic CE. Oral albendazole was administered initially, but rupture of a lung hydatid cyst was observed. To avoid additional rupture, we performed two surgeries. CE is very rare in Japan; all CE cases in Japan during the past two decades have been confirmed to be imported, and almost all cases are hepatic CE. This case is the first case report of a Japanese patient who had concomitant giant lung and liver CE with early-stage CE1 and was successfully treated by surgery and pharmacotherapy with a serological follow-up.

We describe the first detailed histological description of an excised calcified Taenia solium granuloma from a patient who developed recurrent seizures associated with perilesional edema surrounding a calcified cysticercus (PEC). The capsule, around a degenerated cysticercus, contained marked mononuclear infiltrates that extended to adjacent brain, which showed marked astrocytosis, microgliosis, and inflammatory perivascular infiltrates. The presence of large numbers of mononuclear cells supports an inflammatory cause of PEC. Immunosuppression or anti-inflammatory measures may be able to treat and prevent PEC and recurrent seizures.

Cryptosporidium is a significant cause of diarrheal disease in children in developing countries. The sporozoite antigen Muc4 is important for infection of host cells, and could be a candidate vaccine antigen. However, this antigen is polymorphic between Cryptosporidium hominis and C. parvum. We investigated antibody responses to C. hominis Muc4 and C. parvum Muc4 antigen in children in Bangladesh infected with C. hominis. Antibody responses were compared between children with cryptosporidial diarrhea (cases) and uninfected children with diarrhea (controls). There was a significant IgM response to Muc4 from both species in cases compared with controls, which increased over time, and was higher in children with persistent diarrhea. Despite sequence polymorphisms, antibody responses to C. hominis Muc4 and C. parvum Muc4 were significantly correlated. These results suggest that the human antibody response to Muc4 is cross-reactive between species, but in young children does not mature to an IgG response within the period observed in this study.

Global leptospirosis disease burden estimates are hampered by the lack of scientifically sound data from countries with probable high endemicity and limited diagnostic capacities. We describe the seroepidemiologic and clinical characteristics of the leptospirosis outbreak in 2008 in Sri Lanka. Definitive/presumptive case definitions proposed by the World Health Organization Leptospirosis Epidemiology Reference Group were used for case confirmation. Of the 404 possible cases, 155 were confirmed to have leptospirosis. Highest titers of patient seum samples reacted with serovars Pyrogenes (28.7%), Hardjo (18.8%), Javanica (11.5%), and Hebdomadis (11.5%). Sequencing of the 16S ribosomal DNA gene identified six infections: five with Leptospira interrogans and one with L. weilli. In this patient population, acute renal failure was the main complication (14.8%), followed by myocarditis (7.1%) and heart failure (3.9%). The case-fatality rate was 1.3%. This report strengthens the urgent need for increasing laboratory diagnostic capabilities to determine the causes of epidemic and endemic infectious diseases in Sri Lanka, a finding relevant to other tropical regions.

The aim of this study is to investigate the changes in clinical pattern and therapeutic measures in leptospirosis-associated acute kidney injury; a retrospective study with 318 patients in Brazil. Patients were divided according to the time of admission: 1985–1996 (group I) and 1997–2010 (group II). Patients were younger in group I (36 ± 13 versus 41 ± 16 years, P = 0.005) and the numbers of oliguria increased (21% versus 41% in group II, P = 0.014). Higher frequency of lung manifestations was observed in group II (P < 0.0001). Although increased severity, there was a significant reduction in mortality (20% in group I versus 12% in group II, P = 0.03). Mortality was associated with advanced age, low diastolic blood pressure, oliguria, arrhythmia, and peritoneal dialysis, besides a trend to better mortality with penicillin administration. Leptospirosis is occurring in an older population, with a higher number of oliguria and lung manifestations. However, mortality is decreasing and can be the result of changes in treatment.

Rhoptry protein 2 (ROP2) of Toxoplasma gondii is a rhoptry-secreted protein that plays a critical role in parasitophorous vacuole membrane formation during invasion. In previous studies, ROP2 has been shown to be efficient in triggering humoral and cell-mediated responses. High immunogenicity of ROP2 makes it a potential candidate for diagnosis and vaccination against toxoplasmosis. In this study, the ROP2 gene was cloned into pPICZα A expression vector and extracellularly expressed in the yeast Pichia pastoris, which has numerous advantages over other expression systems for eukaryotic proteins expression. The effectiveness of the secreted recombinant ROP2 as a diagnosis agent was assessed by Western Blot with 200 human serum samples. Recombinant ROP2 reacted with toxoplasmosis-positive human serum samples and yielded an overall sensitivity of 90% and specificity of 95%. However, recombinant ROP2 is a better marker for detection of IgG (91.7%) rather than IgM (80%).

The purpose of this study was to conduct an entomological analysis, determination of feeding sources, and molecular identification of triatomines in five communities of the Istmo de Tehuantepec, Oaxaca. The only found species in two of five searched communities (San Mateo del Mar and Tehuantepec City) was Triatoma phyllosoma. Colonization indices were high in both communities. In San Mateo del Mar, the insects were found indoors and in Tehuantepec City in peridomestic areas. The Trypanosoma cruzi infection indices were 2.1% in San Mateo del Mar and 39.4% in Tehuantepec City. This difference could be related to the high numbers of triatomine feeding on hens in the former community. In contrast, in Tehuantepec, dogs were the principal triatomine feeding sources. All nymphs and adults that were genetically analyzed belonged to the species T. phyllosoma. Low levels of genetic variation were found between vectors from both communities.

Recurrent outbreaks of marine pufferfish poisoning in Bangladesh highlight the need to understand the context in which the outbreaks occurred. In a recent outbreak investigation, a multidisciplinary team conducted a mixed-method study to identify the demography and clinical manifestation of the victims and to explore different uses of pufferfish, and local buying, selling, and processing practices. The outbreak primarily affected a low income household where an elderly woman collected and cooked pufferfish egg curry. Nine persons consumed the curry, and symptoms developed in 6 (67%) of these persons. Symptoms included vomiting, diarrhea, paresis, and tingling sensation; 2 (22%) persons died. The unstable income of the affected family, food crisis, and the public disposal of unsafe pufferfish byproducts all contributed to the outbreak. A multi-level intervention should be developed and disseminated with the participation of target communities to discourage unsafe discarding of pufferfish scraps and to improve the community knowledge about the risk of consuming pufferfish.

Far-eastern spotted fever is an emerging disease caused by Rickettsia heilongjiangensis, a tick-borne obligate intracellular bacterium. In this study, R. heilongjiangensis was used to infect BALB/c mice by inoculation of retro-orbital venous plexus to imitate a blood infection caused by tick biting. We found that R. heilongjiangensis rapidly entered the circulation for systemic dissemination and the pathogen existed in liver, spleen, lungs, and brain of the mice at least 9 days post-infection (p.i.). Severe pathological lesions were observed in liver, lungs, and brain at Day 6 p.i. In addition, the elevated levels of inflammatory cytokines, including interferon-γ, tumor necrosis factor, and CC chemokine, were detected in the infected organs at Day 3 p.i. Our results reveal that R. heilongjiangensis may cause an infection in BALB/c mice and the pathological lesions in the infected mice are associated with host inflammatory response induced by R. heilongjiangensis.

Virulence of Rhodococcus equi strains from 20 humans in Brazil was investigated by using a polymerase chain reaction to characterize isolates as virulent (VapA), intermediately virulent (VapB), and avirulent. Nine isolates were obtained from human immunodeficiency virus (HIV)–positive patients, six from HIV-negative patients, and five from patients of unknown status. Five isolates were VapB positive, four were VapA positive, and eleven were avirulent. Among the nine isolates from HIV-positive patients, five contained VapB plasmids and two contained VapA plasmids. Five VapB-positive isolates had the type 8 virulence plasmid. Eleven of the patients had a history of contact with livestock and/or a farm environment, and none had contact with pigs.

Worldwide, the male to female ratio of new smear-positive tuberculosis (TB) cases is approximately two to one. However, in Pakistan, this is not the case. Rates of notified TB cases are 20–30% higher in young females compared with males, and female rates remain high regardless of increasing age. This is in stark contrast to neighboring India, which is characterized by an excess of male TB cases. It is currently unknown why rates of notified TB are so high in females in Pakistan, but it is clear that this epidemiology is a public health issue of importance that impacts transmission dynamics and disease control initiatives.

Trachoma control strategies, including latrine construction and antibiotic distribution, are directed at reducing ocular chlamydia, but may have additional benefits. In a cluster-randomized clinical trial, 24 subkebeles (administrative geographic units) in Ethiopia were offered a single mass azithromycin treatment, and half were randomized to receive an intensive latrine promotion. At a follow-up census 26 months after the baseline treatment, 320 persons had died. The mortality rate of children 1–5 years of age was 3.87 (95% confidence interval [CI] = 2.19–6.82) per 1,000 person-years in the latrine promotion arm, and 2.72 (95% CI = 1.37–5.42) per 1,000 person-years in the control arm. In a multi-level mixed effects logistic regression model controlling for age, there was no difference in mortality in persons randomized into the latrine or control arms (odds ratio = 1.18, 95% CI = 0.89–1.58). Latrine promotion provided no additional effect on mortality in the context of an azithromycin distribution program (clinicaltrials.gov, #NCT00322972).

American tegumentary leishmaniasis (ATL) and human immunodeficiency virus (HIV) are both common infectious diseases in the Brazilian Amazon with overlapping expansion areas, which leads to the occurrence of Leishmania/HIV coinfection. Most ATL/HIV–acquired immunodeficiency syndrome (AIDS) association cases have been reported from areas where Leishmania (Viannia) braziliensis is the main pathogen; this finding is in contrast with the Amazon region, where L. (V.) guyanensis is the most implicated agent, implying distinct clinical and therapeutic aspects. We describe 15 cases of ATL/HIV coinfection treated in a tertiary care center in the Brazilian Amazon between 1999 and 2008. Thirteen patients presented with diverse clinical manifestations of cutaneous leishmaniasis, and four of them had disseminated forms; two patients presented with mucosal leishmaniasis (ML). Seven patients required more than one course of treatment. The particularities of ATL/HIV-AIDS association in L. (V.) guyanensis-endemic areas require efforts for an increased understanding of its burden and subsequent improvements in case management.

Post–kala-azar dermal leishmaniasis (PKDL) is a complication of visceral leishmaniasis. Bangladesh national treatment guidelines during the study period called for 120 intramuscular injections of sodium antimony gluconate (SAG). We assessed care-seeking behavior, diagnosis and treatment costs, and coping strategies among 134 PKDL patients; 56 (42%) patients had been treated with SAG, and 78 (58%) remained untreated. The median direct cost per patient treated was US$367 (interquartile range [IQR] = 90–284), more than two times the estimated per capita annual income for the study population. The most common coping strategy was to take a loan; the median amount borrowed was US$98 (IQR = 71–150), with a median interest of US$32 (IQR = 16–95). Households lost a median of 123 work-days per patient treated. The current regimen for PKDL imposes a significant financial burden, reinforcing the link between poverty and visceral leishmaniasis. More practical shorter-course regimens for PKDL are urgently needed to achieve national and regional visceral leishmaniasis elimination goals.

Some protozoan infections such as Toxoplasma, Cryptosporidium, and Plasmodium can be transmitted through stem cell transplantations. To our knowledge, so far, there is no study about transmission of Leishmania parasites in stem cell transplantation and interactions between parasites and stem cells in vitro. Therefore, the aim of this study was to investigate the interaction between different species of Leishmania parasites and adipose tissue-derived mesenchymal stem cells (ADMSCs). ADMSCs have been isolated, cultured, characterized, and infected with different species of Leishmania parasites (L. donovani, L. major, L. tropica, and L. infantum). Infectivity was examined by Giemsa staining, microculture, and polymerase chain reaction methods. As a result, infectivity of ADMSCs by Leishmania parasites has been determined for the first time in this study. According to our findings, it is very important that donors are screened for Leishmania parasites before stem cell transplantations in regions where leishmaniasis is endemic.

Despite the recent discovery of genetically divergent hantaviruses in shrews of multiple species in widely separated geographic regions, data are unavailable about the genetic diversity and phylogeography of Thottapalayam virus (TPMV), a hantavirus originally isolated from an Asian house shrew (Suncus murinus) captured in southern India more than four decades ago. To bridge this knowledge gap, the S, M, and L segments of hantavirus RNA were amplified by reverse transcription polymerase chain reaction from archival lung tissues of Asian house shrews captured in Nepal from January to September 1996. Pair-wise alignment and comparison revealed approximately 80% nucleotide and > 94% amino acid sequence similarity to prototype TPMV. Phylogenetic analyses, generated by maximum likelihood and Bayesian methods, showed geographic-specific clustering of TPMV, similar to that observed for rodent- and soricid-borne hantaviruses. These findings confirm that the Asian house shrew is the natural reservoir of TPMV and suggest a long-standing virus–host relationship.

Paracoccidioidomycosis has been known for over 100 years, and until now, there were only few estimates of the disease's incidence. We aim to analyze 1,000 cases treated between 1960 and 1999 at Ribeirão Preto city, São Paulo, Brazil, where the disease's incidence range detected was 1.6 to 3.7 cases per 100,000 habitants per year (mean = 2.7 cases/year). We observed a male to female ratio of 6:1 and an age distribution from 3 to 85 years. The acute/subacute form of the disease accounted for 25.4% of cases. Most of the patients (93.5%) had lived or worked in rural areas before the disease development. Smoking and alcoholism were reported by 64.7% and 37.2% of patients, respectively. Comorbidities identified included tuberculosis (8.3%), Chagas' disease (8.6%), and human immunodeficiency virus/acquired immunodeficiency syndrome (4.2%). The present study revealed an area in Brazil where paracoccidioidomycosis is hyperendemic (has the highest reported incidence of this disease); this endemic area is probably caused by geological and climatic conditions as well as intensive agriculture.

Usutu virus (USUV) is a mosquito-borne flavivirus that emerged 2001 in Austria and caused deaths in wild birds. In Germany, 70,378 female mosquitoes were captured in 2009 and 2010 and assayed for USUV. Virus was isolated in cell culture from one pool of Culex pipiens pipiens mosquitoes trapped exclusively in August 2010 in Weinheim, Germany. Subsequent phylogenetic analysis demonstrated a close relationship between the isolated USUV strain from Germany and a USUV strain from Austria, which was detected in a dead blackbird in 2004.

Historically, native populations in the Republic of Djibouti have experienced only low and unstable malaria transmission and intermittent epidemics. In recent years, efforts at malaria control have been aggressively pursued. This study was performed to inform revised malaria prevention recommendations for military service members and international travelers to the country. Laboratory-confirmed cases of malaria documented at large medical facilities and within military and civilian health care systems in the Republic of Djibouti from 1998 to 2009 were reviewed. In recent years, fewer than 5% of febrile cases among the three largest passive surveillance systems were laboratory-confirmed as malaria, and incidence of confirmed malaria was well below 1/1,000 persons/year. As efforts in the Republic of Djibouti progress toward elimination, and in conjunction with continued efforts at surveillance, emphasizing mosquito-avoidance measures and standby emergency treatment will become reasonable recommendations for malaria prevention.

Despite significant reductions in the overall burden of malaria in the 20th century, this disease still represents a significant public health problem in China, especially in central areas. Understanding the spatio-temporal distribution of malaria is essential in the planning and implementing of effective control measures. In this study, normalized meteorological factors were incorporated in spatio-temporal models. Seven models were established in WinBUGS software by using Bayesian hierarchical models and Markov Chain Monte Carlo methods. M 1, M 2, and M 3 modeled separate meteorological factors, and M 3, which modeled rainfall performed better than M 1 and M 2, which modeled average temperature and relative humidity, respectively. M 7 was the best fitting models on the basis of based on deviance information criterion and predicting errors. The results showed that the way rainfall influencing malaria incidence was different from other factors, which could be interpreted as rainfall having a greater influence than other factors.

The aim of this study was to investigate the association between genetic polymorphisms of Plasmodium falciparum chloroquine resistance transporter (pfcrt), P. falciparum multidrug resistance 1 (pfmdr1), and P. falciparum ATPase (pfatp6) and clinical outcome after a three-day mefloquine-artesunate combination therapy in 134 patients with uncomplicated Plasmodium falciparum malaria in an area with multidrug resistance along the Thailand-Myanmar border. Analysis of gene mutation and amplification were performed by nested real-time polymerase chain reaction and SYBR Green I real-time polymerase chain reaction, respectively. The mutation for pfcrt (codons 76, 220, 271, 326, 356, and 371) was found in all isolates (100%), whereas no mutation of pfmdr1 (codon 86) and pfatp6 (codons 37, 693, 769, 898) was found. The Pfmdr1 copy number was significantly higher in isolates with recrudescence (median number = 2.44) compared with a sensitive response (median number = 1.44). The gene copy number was also found to be significantly higher in paired isolates collected before treatment and at the time of recrudescence. All isolates carried one pfatp6 gene copy.

We evaluated the efficacy and effectiveness of mefloquine (MQ) plus artesunate (AS) to treat patients with uncomplicated malaria in the Peruvian Amazon Basin in April 2005–March 2006. Patients ≥ 1 year of age with fever (axillary temperature ≥ 37.5°C) or history of fever and Plasmodium falciparum monoinfection were included. Patients received antimalarial treatment with MQ (12.5 mg/kg/day for two days) and AS (4.0 mg/kg/day for three days) either by directly observed therapy or without directly observed therapy. After a 28-day follow-up, treatment efficacy and effectiveness were assessed on the basis of clinical and parasitologic outcomes. Ninety-six patients were enrolled in each study group; nine patients were lost to follow-up. All patients, except for one in the observed group, demonstrated adequate clinical and parasitologic response; none had detectable parasitemia on day 3. The efficacy of MQ + AS efficacy was 98.9% (95% confidence interval = 94.1–100.0%) and the effectiveness was 100.0% (95% confidence interval = 95.9–100.0%). Our study shows that MQ + AS is highly efficacious in the Peruvian Amazon.