Microscopic Evidence of Malaria Infection in Visceral Tissue from Medici Family, Italy.

Microscopy of mummified visceral tissue from a Medici family member in Italy identified a potential blood vessel containing erythrocytes. Giemsa staining, atomic force microscopy, and immunohistochemistry confirmed Plasmodium falciparum inside those erythrocytes. Our results indicate an ancient Mediterranean presence of P. falciparum, which remains responsible for most malaria deaths in Africa.

Five accelerated schedules for the tick-borne encephalitis vaccine FSME-Immun® in last-minute travellers: an open-label, single-Centre, randomized controlled pilot trial.

BACKGROUND: The purpose of this exploratory study was to evaluate different accelerated tick-borne encephalitis (TBE) vaccine schedules for last-minute travellers. METHODS: In a single-centre, open-label pilot study, 77 TBE-naïve Belgian soldiers were randomized to one of the following five schedules with FSME-Immun®: group 1 ('classical accelerated' schedule) received one intramuscular (IM) dose at day 0 and day 14, group 2 two IM doses at day 0, group 3 two intradermal (ID) doses at day 0, group 4 two ID doses at day 0 and day 7, group 5 two ID doses at day 0 and day 14. The last dose(s) of the primary vaccination scheme were given after one year: IM (1 dose) or ID (2 doses). TBE virus neutralizing antibodies were measured in a plaque reduction neutralization test (PRNT90 and 50) at day 0, 14, 21, 28, month 3, 6, 12, and 12 + 21 days. Seropositivity was defined as neutralizing antibody titres ≥10. RESULTS: The median age was 19-19.5 years in each group. Median time-to-seropositivity up to day 28 was shortest for PRNT90 in ID-group 4 and for PRNT50 in all ID groups. Seroconversion until day 28 peaked highest for PRNT90 in ID-group 4 (79%) and for PRNT50 in ID-groups 4 and 5 (both 100%). Seropositivity after the last vaccination after 12 months was high in all groups. Previous yellow fever vaccination was reported in 16% and associated with lower GMTs of TBE-specific antibodies at all time points. The vaccine was generally well tolerated. However, mild to moderate local reactions occurred in 73-100% of ID compared to 0-38% of IM vaccinations, persistent discolouration was observed in nine ID vaccinated individuals. CONCLUSION: The accelerated two-visit ID schedules might offer a better immunological alternative to the recommended classical accelerated IM schedule but an aluminium-free vaccine would preferable.

Characteristics of confirmed mpox cases among clinical suspects: A prospective single-centre study in Belgium during the 2022 outbreak.

Background: The presentation of mpox clade IIb during the 2022 outbreak overlaps with a range of other diseases. Understanding the factors associated with mpox is important for clinical decision making. Methods: We described the characteristics of mpox patients who sought care at Belgian sexual health clinic. Furthermore we compared their characteristics to those of patients with a clinical suspicion of mpox but who tested negative on polymerase chain reaction. Results: Between May 23 and September 20, 2022, 155 patients were diagnosed with mpox, and 51 patients with suspected symptoms tested negative. All mpox patients self-identified as men and 148/155 (95.5%) as gay or bisexual MSM. Systemic symptoms were present in 116/155 (74.8%) patients. All but 10 patients (145/155, 93.5%) presented with skin lesions. Other manifestations were lymphadenopathy (72/155, 46.5%), proctitis (50/155, 32.3%), urethritis (12/155, 7.7%), tonsillitis (2/155, 1.3%). Complications involved bacterial skin infection (13/155, 8.4%) and penile oedema with or without paraphimosis (4/155, 2.6%). In multivariable logistic regression models, the presence of lymphadenopathy (OR 3.79 95% CI 1.44-11.49), skin lesions (OR 4.35 95% CI 1.15-17.57) and proctitis (OR 9.41 95% CI 2.72-47.07) were associated with the diagnosis of mpox. There were no associations with age, HIV status, childhood smallpox vaccination, number of sexual partners and international travel. Conclusions: The presence of proctitis, lymphadenopathies and skin lesions should increase clinical suspicion of mpox in patients with compatible symptoms.

Persistent morbidity in Clade IIb mpox patients: interim results of a long-term follow-up study, Belgium, June to November 2022.

While mpox was well characterised during the 2022 global Clade IIb outbreak, little is known about persistent morbidity. We present interim results of a prospective cohort study of 95 mpox patients assessed 3-20 weeks post-symptom onset. Two-thirds of participants had residual morbidity, including 25 with persistent anorectal and 18 with genital symptoms. Loss of physical fitness, new-onset/worsened fatigue and mental health problems were reported in 36, 19 and 11 patients, respectively. These findings require attention by healthcare providers.

Alternative sampling specimens for the molecular detection of mpox (formerly monkeypox) virus.

BACKGROUND: Mpox (formerly monkeypox) is a viral disease caused by the mpox virus (MPXV), endemic in Central and West Africa and currently causing a global outbreak of international concern. Much remains unknown about sample types most suited for mpox laboratory diagnosis. While it is established that high viral loads can be found in active skin lesions (currently the recommended mpox laboratory confirmation specimen type), WHO mpox testing guidelines encourage the use of oropharyngeal swabs as an additional sample type for mpox diagnosis and suggest investigating the value of other specimens like blood samples. OBJECTIVE: In this study, we verified the value of select alternative specimen types for mpox laboratory confirmation. METHODS: We included 25 patients with MPXV-confirmed skin lesions to compare diagnostic sensitivity of MPXV PCR testing on EDTA plasma and two upper respiratory specimens: oropharyngeal swabs and saliva. RESULTS: In our patient cohort with MPXV-confirmed skin lesions, diagnostic sensitivity of MPXV PCR was 80% in EDTA plasma, 64% in oropharyngeal swabs, and 88% in saliva. MPXV viral loads were significantly higher in saliva compared to oropharyngeal swabs and EDTA plasma. DISCUSSION: The WHO recommendation to collect oropharyngeal swabs as an additional specimen for mpox diagnosis might need to be revised to include saliva wherever feasible. We suggest investigating saliva as a diagnostic specimen in the absence of active skin lesions or during the phase preceding skin manifestations. Moreover, the relatively high MPXV DNA content of saliva warrants elucidating its potential role in disease transmission.

Understanding sexual transmission dynamics and transmission contexts of monkeypox virus: a mixed-methods study of the early outbreak in Belgium (May-June 2022).

OBJECTIVE: The available epidemiological and clinical evidence from the currently ongoing monkeypox (MPX) outbreak in non-endemic areas suggests an important factor of sexual transmission. However, limited information on the behaviour and experiences of individuals with an MPX infection has to date been provided. We aimed to describe the initial phase of the MPX outbreak in Belgium, and to provide a more in-depth description of sexual behaviour and transmission contexts. METHODS: We used routine national surveillance data of 139 confirmed MPX cases with date of symptom onset until 19 June 2022, complemented with 12 semistructured interviews conducted with a subsample of these cases. RESULTS: Sexualised environments, including large festivals and cruising venues for gay men, were the suspected exposure setting for the majority of the cases in the early outbreak phase. In-depth narratives of sexual behaviour support the hypothesis of MPX transmission through close physical contact during sex. Despite awareness of the ongoing MPX outbreak, low self-perceived risk of MPX acquisition and confusing initial signs and symptoms for other STIs or skin conditions delayed early detection of an MPX infection. In addition, we describe relevant contextual factors beyond individual behaviour, related to sexual networks, interpersonal interactions and health systems. Some of these factors may complicate early MPX detection and control efforts. CONCLUSION: Our results highlight the role of sexual contact and networks in the transmission of MPX during the early phase of the outbreak in Belgium. Risk communication messages should consistently and transparently state the predominant sexual transmission potential of MPX virus, and prevention and control measures must be adapted to reflect multilevel factors contributing to MPX transmission risk.

Severe mpox (formerly monkeypox) disease in five patients after recent vaccination with MVA-BN vaccine, Belgium, July to October 2022.

Vaccination is important in containing the 2022 mpox (formerly monkeypox) epidemic. We describe five Belgian patients with localised severe symptoms of proctitis and penile oedema, occurring between 4 and 35 days after post-exposure preventive vaccination or after one- or two-dose off-label pre-exposure preventive vaccination with MVA-BN vaccine. Genome sequencing did not reveal evidence for immune escape variants. Healthcare workers and those at risk should be aware of possible infections occurring shortly after vaccination and the need for other preventive measures.

Glucose-6-phosphate dehydrogenase activity measured by spectrophotometry and associated genetic variants from the Oromiya zone, Ethiopia.

BACKGROUND: The study aimed to gain first data on the prevalence of G6PD enzyme deficiency measured by spectrophotometry and associated genetic variants in Jimma and surroundings, Ethiopia. The area is a Plasmodium vivax endemic region, but 8-aminoquinolines such as primaquine are not recommended as G6PD testing is not available. METHODS: Healthy volunteers were recruited at Jimma University, Ethiopia. Enzyme activity was tested by spectrophotometry at the University of Ulm, Germany. A G6PD RDT (Binax NOW® G6PD, Alere, USA) was additionally performed. The G6PD gene was analysed for polymorphisms in a sub-population. Tests for haemoglobinopathies and the presence of malaria parasites were conducted. RESULTS: No severe or moderate (cut-off 60%) G6PD deficiency was found in 206 volunteers. Median male activity was 6.1 U/g Hb. Eleven participants (5.4%) showed activities between 70 and 80%. No haemoglobinopathy was detected. None of the subjects showed asymptomatic parasitaemia. One G6PD-A+ variant (A376G) and one new non-synonymous mutation (G445A) were found. CONCLUSIONS: As the prevalence of G6PD deficiency seems low in this area, the use of 8-aminoquinolines should be encouraged. However, reliable G6PD testing methods have to be implemented and safe cut-off levels need to be defined.

Intermittent screening and treatment with artemether-lumefantrine versus intermittent preventive treatment with sulfadoxine-pyrimethamine for malaria in pregnancy: a facility-based, open-label, non-inferiority trial in Nigeria.

BACKGROUND: The spread of SP resistance may compromise the effectiveness of intermittent preventive treatment of malaria in pregnancy (MiP) with sulfadoxine-pyrimethamine (IPTp-SP) across Africa. However, there is no recommended alternative medicine for IPTp or alternative strategy for prevention of MiP. This poses problems for the prevention of MiP. This study investigated, whether screening with a rapid diagnostic test for malaria at routine antenatal clinic attendances and treatment of only those who are positive (intermittent screening and treatment) with artemether-lumefantrine is as effective and safe as IPTp-SP in pregnant women. METHODS: During antenatal clinic sessions at the General Hospital Calabar, Nigeria, held between October 2013 and November 2014, 459 pregnant women were randomized into either the current standard IPTp-SP or intermittent screening and treatment with artemether-lumefantrine (ISTp-AL). All women received a long-lasting insecticide-treated net at enrolment. Study women had a maximum of four scheduled visits following enrolment. Haemoglobin concentration and peripheral parasitaemia were assessed in the third trimester (36-40 weeks of gestation). Birth weight was documented at delivery or within a week for babies delivered at home. RESULTS: In the third trimester, the overall prevalence of severe anaemia (Hb < 8 g/dl) and moderate (8-10.9 g/dl) anaemia was 0.8 and 27.7%, respectively, and was similar in both treatment groups (p = 0.204). The risk of third-trimester severe anaemia did not differ significantly between both treatment arms (risk difference - 1.75% [95% CI - 4.16 to 0.66]) although the sample was underpowered for this outcome due to several participants being unavailable to give a blood sample. The risk of third-trimester maternal parasitaemia was significantly lower in the ISTp-AL arm (RD - 3.96% [95% CI - 7.76 to - 0.16]). The risk of low birthweight was significantly lower in the ISTp-AL arm after controlling for maternal age, gravidity and baseline parasitaemia (risk difference - 1.53% [95% CI - 1.54 to - 1.15]). Women in the ISTp-AL arm complained of fever more frequently compared to women in the IPTp-SP arm (p = 0.022). CONCLUSIONS: The trial results suggest that in an area of high malaria transmission with moderate sulfadoxine-pyrimethamine resistance, ISTp with artemether-lumefantrine may be an effective strategy for controlling malaria in pregnancy. Trial registration PACTR, PACTR201308000543272. Registered 29 April 2013, http://www.pactr.org/ATMWeb/appmanager/atm/atmregistry?dar=true&tNo=PACTR201308000543272.

Reduction of malaria prevalence after introduction of artemisinin-combination-therapy in Mbeya Region, Tanzania: results from a cohort study with 6773 participants.

BACKGROUND: A marked decline in malaria morbidity and mortality has been reported after the introduction of artemisinin-based combination therapy (ACT) in high malaria prevalence countries in Africa. Data on the impact of ACT and on the prevalence of malaria has so far been scarce for Southwest Tanzania. METHODS: Between 2005 and 2011, a large general population cohort in the Mbeya Region in the south-west of Tanzania has been surveyed within the EMINI-study (Evaluation and Monitoring of the Impact of New Interventions). Participants were examined once per year, including rapid diagnostic testing for malaria. ACT was introduced in the region according to national guidelines in the time period 2006/2007, replacing sulfadoxine/pyrimethamine as first-line therapy. In four study sites, 6773 individuals who participated in the first two of three consecutive survey visits in the period from 2006 to 2009 were included in this analysis. The prevalence of Plasmodium infection prior to and after the introduction of ACT was compared by logistic regression, with consideration of climatic variability, age, sex, socio-economic status and bed net use as potential confounders. RESULTS: A significant reduction over time in the prevalence of Plasmodium falciparum infection from 2.5 to 0.3% was shown across the four study sites. The decline was not explained by other factors included in the analysis, therefore, the decline over time most likely reflects the impact of introduction of ACT in the study area. CONCLUSIONS: The longitudinal study showed a significant and relevant decline in the prevalence of P. falciparum infection after introduction of ACT, which could not be explained by potential confounders. The data suggests that artemisinin-based combinations are not only an effective instrument for reduction of immediate morbidity and mortality, but also for reduction of transmission rates.

Prevalence of the Pfdhfr and Pfdhps mutations among asymptomatic pregnant women in Southeast Nigeria.

Sulfadoxine-pyrimethamine (SP) is the recommended drug for intermittent preventive treatment of malaria in pregnancy in most of sub-Saharan Africa. Resistance to SP is related to mutations in the dhfr and dhps gene of Plasmodium falciparum. This study determined the prevalence of Pfdhfr and Pfdhps polymorphisms found in asymptomatic pregnant women attending antenatal care in Calabar, Nigeria. From October 2013 to November 2014, asymptomatic pregnant women attending antenatal care clinics were enrolled after obtaining informed consent. Malaria diagnosis testing was done using thick and thin smears. Dried blood spot filter papers were collected. Parasite DNA was extracted from the filter papers using a chelex extraction. Extraction was followed by nested PCR and restriction enzyme digestion. P. falciparum infection was detected by microscopy in 7% (32/459) participants. Twenty-eight P. falciparum isolates were successfully genotyped. In the Pfdhfr gene, the triple mutation was almost fixed; S108N mutation was (100%), N51I (93%) and C59R mutations (93%), whereas the I164L mutation was absent. The prevalence of Pfdhps S436A, A437G, A581G and A613S mutations was 82.1% (23/28), 96.4% (27/28), 71.4% (20/28) and 71.4% (20/28) respectively. The K540E mutation was absent. The prevalence of the Pfdhfr triple mutation IRNI was 92.9% (26/28). The efficacy of SP as IPTp in Southeast Nigeria may be severely threatened. The continuous monitoring of SP molecular markers of resistance is required to assess thresholds. The evaluation of alternative preventive treatment strategies and drug options for preventing malaria in pregnancy may be necessary.

Comparison of four PCR methods for efficient detection of Trypanosoma cruzi in routine diagnostics.

Due to increased migration, Chagas disease has become an international health problem. Reliable diagnosis of chronically infected people is crucial for prevention of non-vectorial transmission as well as treatment. This study compared four distinct PCR methods for detection of Trypanosoma cruzi DNA for the use in well-equipped routine diagnostic laboratories. DNA was extracted of T. cruzi-positive and negative patients' blood samples and cultured T. cruzi, T. rangeli as well as Leishmania spp. One conventional and two real-time PCR methods targeting a repetitive Sat-DNA sequence as well as one conventional PCR method targeting the variable region of the kDNA minicircle were compared for sensitivity, intra- and interassay precision, limit of detection, specificity and cross-reactivity. Considering the performance, costs and ease of use, an algorithm for PCR-diagnosis of patients with a positive serology for T. cruzi antibodies was developed.

Cross-sectional, descriptive study of Chagas disease among citizens of Bolivian origin living in Munich, Germany.

PURPOSE: Chagas disease (CD) has become a global health issue mainly due to migration. Germany lacks surveillance data and is home to a large Latin American immigrant population. Recognising that Bolivia is the country with the highest CD prevalence in Latin America, this cross-sectional, descriptive pilot study investigated CD and associated factors among citizens of Bolivian origin living in Munich, Germany. METHODS: Participants completed a questionnaire in order to collect socioeconomic and health-related data. In addition, serology was performed. In case of positive serological tests, PCR diagnostic and clinical staging together with disease management was initiated. Qualitative research was conducted to identify personal and community barriers as well as strategies to increase CD awareness among the population at risk. RESULTS: Between June 2013 and June 2014, 43 people from Bolivia (or descendants) were enrolled. A total of 9.3% (4/43), of whom two women were of childbearing age, tested seropositive (ELISA and IFAT), and one also by PCR. For 2/4 positive participants, clinical evaluation was performed and the indeterminate form of CD was diagnosed. Knowledge about CD symptoms and ways of transmission were completely absent among 55.8% (24/43, 2/4 with CD) and 30.2% (13/43, 1/4 with CD) of participants, respectively. A total of 27.9% (12/43, 0/4 with CD) of participants had donated blood prior to the study, whereas 62.8% (27/43, 3/4 with CD) were motivated to donate blood in the future. The qualitative research identified lack of knowledge as well as stigma and fears related to CD. CONCLUSIONS: Despite the small number of participants, the prevalence of CD as well as the potential risk of non-vectorial transmission was alarming. Campaigns adapted for Latin American migrants as well as control strategies should be developed and put in place in order to prevent non-vectorial transmission and actively detect cases of CD in Germany.

Similar trends of susceptibility in Anopheles arabiensis and Anopheles pharoensis to Plasmodium vivax infection in Ethiopia.

BACKGROUND: Around half of the global population is living in areas at risk of malaria infection. Plasmodium vivax malaria has become increasingly prevalent and responsible for a high health and socio-economic burden in Ethiopia. The availability of gametocyte carriers and mosquito species susceptible to P. vivax infection are vital for malaria transmission. Determining the susceptibility of vector species to parasite infection in space and time is important in vector control programs. This study assesses the susceptibility of Anopheles arabiensis, An. pharoensis and An. coustani group to Plasmodium vivax infection in Ethiopia. METHODS: Larvae of An. arabiensis, An. pharoensis and An. coustani group were collected from an array of breeding sites and reared to adult under controlled conditions. Batches of adult female mosquitoes of the three species were allowed to feed in parallel on the same infected blood with gametocytes drawn from Plasmodium vivax infected patients by Direct Membrane Feeding Assays (DMFA). Fed mosquitoes were kept in an incubator under controlled laboratory conditions. Seven days after each feeding assay, mosquitoes were dissected for midgut oocyst microscopy and enumeration. Data were analysed using R statistical software package version 3.1.0. RESULTS: Over all, 8,139 adult female mosquitoes were exposed to P. vivax infection. Of the exposed mosquitoes 16.64 % (95 % CI: 1,354-8,139) were properly fed and survived until dissection. The infection rate in An. arabiensis and An. pharoensis was 31.72 % (95 % CI: 28.35-35.08) and 28.80 % (95 % CI: 25.31-32.28), respectively. The intensity of infection for An. arabiensis and An. pharoensis was 2.5 (95 % CI: 1.9-3.2) and 1.4 (95 % CI: 1.1-1.8), respectively. Gametocyte density was positively correlated to infection rate and intensity of infection in An. arabiensis as well as An. pharoensis. No An. coustani group mosquitoes were found infected, though almost four hundred mosquitoes were successfully fed and dissected. All groups received blood from the same infected blood source containing gametocytes in parallel. There was no significant difference in susceptibility rates between An. arabiensis and An. pharoensis (P = 0.215). CONCLUSIONS: Anopheles arabiensis and An. pharoensis showed similar susceptibility to P. vivax infection. However, An. coustani group was not permissive for the development of P. vivax parasites.

Comparison of Intranasal Outer Membrane Vesicles with Cholera Toxin and Injected MF59C.1 as Adjuvants for Malaria Transmission Blocking Antigens AnAPN1 and Pfs48/45.

Purified protein vaccines often require adjuvants for efficient stimulation of immune responses. There is no licensed mucosal adjuvant on the market to adequately boost the immune response to purified antigens for intranasal applications in humans. Bacterial outer membrane vesicles (OMV) are attractive candidates potentially combining antigenic and adjuvant properties in one substance. To more precisely characterize the potential of Escherichia coli OMV for intranasal vaccination with heterologous antigens, immune responses for AnAPN1 and Pfs48/45 as well as ovalbumin as a reference antigen were assessed in mice. The intranasal adjuvant cholera toxin (CT) and parenteral adjuvant MF59C.1 were used in comparison. Vaccinations were administered intranasally or subcutaneously. Antibodies (total IgG and IgM as well as subclasses IgG1, IgG2a, IgG2b, and IgG3) were measured by ELISA. T cell responses (cytotoxic T cells, Th1, Th17, and regulatory T cells) were determined by flow cytometry. When OMV were used as adjuvant for intranasal immunization, antibody and cellular responses against all three antigens could be induced, comparable to cholera toxin and MF59C.1. Antigen-specific IgG titres above 1 : 10(5) could be detected in all groups. This study provides the rationale for further development of OMV as a vaccination strategy in malaria and other diseases.

Lymphocytosis and Lymphopenia Induced by Imported Infectious Diseases: A Controlled Cross-Sectional Study of 17,229 Diseased German Travelers Returning from the Tropics and Subtropics.

The present controlled cross-sectional study aimed to assess relative and absolute lymphocytosis and lymphopenia induced by imported infectious diseases (IDs) seen among patients consulting the Division of Infectious Diseases and Tropical Medicine, Medical Center of the University of Munich (1999-2014) after being in the tropics and subtropics. The analysis investigated data sets from 17,229 diseased German travelers returning from Latin America (3,238), Africa (5,467), and Asia (8,524), and from 1,774 healthy controls who had not recently traveled. Among the cases, the proportion of those with relative lymphopenia (10.5%) and absolute lymphopenia (8.0%) was significantly higher than among controls (3.2% and 3.6%, respectively), whereas relative lymphocytosis was significantly lower among cases (6.1%) than among controls (8.0%). The study identified IDs with significantly larger proportions of relative lymphocytosis (cytomegalovirus [CMV] infection [56%], infectious mononucleosis [51%], and dengue fever [11%]); absolute lymphocytosis (infectious mononucleosis [70%] and CMV infection [63%]); relative lymphopenia (streptococcal pharyngitis [56%], malaria [34%], Campylobacter infection [19%], salmonellosis [18%], and shigellosis [17%]); and of absolute lymphopenia (human immunodeficiency virus infection [53%], malaria [45%], dengue fever [40%], salmonellosis [16%], and Campylobacter infection [11%]). This study demonstrates that relative and absolute lymphocytosis and lymphopenia are useful laboratory findings for travelers returning from the tropics and subtropics, as they are typically caused by imported viral, bacterial, and protozoan IDs.

Spectrum of Imported Infectious Diseases: A Comparative Prevalence Study of 16,817 German Travelers and 977 Immigrants from the Tropics and Subtropics.

The aim of this study was to assess the spectrum of imported infectious diseases (IDs) among patients consulting the University of Munich, Germany, between 1999 and 2014 after being in the sub-/tropics. The analysis investigated complete data sets of 16,817 diseased German travelers (2,318 business travelers, 4,029 all-inclusive travelers, and 10,470 backpackers) returning from Latin America (3,225), Africa (4,865), or Asia (8,727), and 977 diseased immigrants, originating from the same regions (112, 654 and 211 respectively). The most frequent symptoms assessed were diarrhea (38%), fever (29%), and skin disorder (22%). The most frequent IDs detected were intestinal infections with species of Blastocystis(900),Giardia(730),Campylobacter(556),Shigella(209), and Salmonella(183). Also frequently observed were cutaneous larva migrans (379), dengue (257), and malaria (160). The number of IDs with significantly elevated proportions was higher among backpackers (18) and immigrants (17), especially among those from Africa (18) and Asia (17), whereas it was lower for business travelers (5), all-inclusive travelers (1), and those from Latin America (5). This study demonstrates a large spectrum of imported IDs among returning German travelers and immigrants, which varies greatly based not only on travel destination and origin of immigrants, but also on type of travel.

[Monkey malaria (Plasmodium knowlesi infection) after travelling to Thailand]. / "Affenmalaria" nach Thailandreise.

A case of malaria caused by Plasmodium knowlesi is described in a 52-year-old female German traveler after returning from Thailand. P. knowlesi is a parasite of macaques in Southeast Asia and has been recognized in recent years as an important and probably increasing cause of human malaria in some areas. At least 16 cases in international travelers have been published so far. This includes four cases imported to Germany. All German patients visited forested areas in Southern Thailand inhabited by the natural monkey host prior to their illness. Most cases diagnosed in endemic areas present as mild disease. However in some patients P. knowlesi may take a severe and life-threatening course. Diagnosis is usually is based on microscopy whereas rapid tests are not reliable. However, microscopic differentiation of P. knowlesi from other plasmodium species (eg, P. malariae, P. falciparum) is difficult, especially when parasitemia is low. Thus PCR methods are required for definite species determination. Changing endemicity as well as changing tourism patterns such as the trend towards eco-tourism might increase the risk of infection for travelers even in areas which are considered as low endemic for malaria. Malaria has to be considered in all febrile patients returning from endemic areas. In Southeast Asia this has to include Plasmodium knowlesi infection. Especially if microscopy suggests P. falciparum/P. malariae double infection, or when results indicate P. malariae but the clinical presentation differs from that of quartan malaria (eg, daily fever), diagnostic procedures for P. knowlesi should be initiated. Currently available rapid diagnostic tests are not reliable for the detection of P. knowlesi. The definite diagnosis of P. knowlesi infection usually requires PCR techniques Changing tourism patterns such as the trend towards eco-tourism might increase the risk of infection for travelers even in low prevalence areas.