The risk of malaria in travelers to India.

BACKGROUND: Several countries have reported a decline in malaria cases imported by travelers returning from India. METHODS: We collected data on imported malaria for the period 1992 to 2005 from nine countries. Traveler statistics denominator data were obtained from the Indian Ministry of Tourism. RESULTS: The malaria case numbers declined from 93 cases per 100,000 travelers in 1992 to 19 cases per 100,000 travelers in 2005. The proportion of Plasmodium falciparum decreased steadily throughout the years. The proportion of Plasmodium vivax accounts for more than 80% of all cases of malaria in travelers to India. Deaths due to malaria were rare; only the UK and the United States reported deaths, a total of 16, between 1992 and 2005. The high-risk areas for malaria in India can be clearly identified using endemic malaria data. High-risk states are Chhattisgarh, Orissa, Jharkhand, West Bengal, Goa (mainly P vivax), and the states east of Bangladesh. CONCLUSIONS: The decreasing incidence of malaria in travelers to India and the high proportion of P vivax support the current change in guidelines in some European countries advocating the use of the standby emergency self-treatment strategy or bite precautions plus awareness of risk instead of chemoprophylaxis. Otherwise in high-risk states, chemoprophylaxis should still be considered particularly in high-transmission seasons.

Imported malaria in children in industrialized countries, 1992-2002.

Children account for an appreciable proportion of total imported malaria cases, yet few studies have quantified these cases, identified trends, or suggested evidence-based prevention strategies for this group of travelers. We therefore sought to identify numbers of cases and deaths, Plasmodium species, place of malaria acquisition, preventive measures used, and national origin of malaria in children. We analyzed retrospective data from Australia, Denmark, France, Germany, Italy, Japan, the Netherlands, Sweden, Switzerland, the United Kingdom, and the United States and data provided by the United Nations World Tourism Organization. During 1992-2002, >17,000 cases of imported malaria in children were reported in 11 countries where malaria is not endemic; most (>70%) had been acquired in Africa. Returning to country of origin to visit friends and relatives was a risk factor. Malaria prevention for children should be a responsibility of healthcare providers and should be subsidized for low-income travelers to high-risk areas.

Travellers returning to Sweden with falciparum malaria: pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay.

We have investigated pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay in travellers returning to Sweden with falciparum malaria. Questionnaires were distributed to patients having been notified with falciparum malaria from 1994 to 2001. Of 408 notified patients, 237 (58%) returned the questionnaires; 62% were males and 43% above the age of 45 y. Africa was the travel destination in 90% of the cases, and 27% had travelled to Kenya. 69% had spent more than 1 night in the countryside, and 6% had stayed in modern urban areas only. 40% took an adequate dose of chemoprophylaxis, although this proportion decreased from 55% to 12% during the study period. Nine per cent used both bed nets and mosquito repellents regularly. The median time from onset of symptoms to contact with health care professionals was 2 d, and from that contact to start of malaria treatment the median time was less than 24 h.

Malaria risk in travelers.

Imported malaria has been an increasing problem in several Western countries in the last 2 decades. To calculate the risk factors of age, sex, and travel destination in Swedish travelers, we used data from the routine reporting system for malaria (mixture of patients with and without adequate prophylaxis), a database on travel patterns, and in-flight or visa data on Swedish travelers of 1997 to 2003. The crude risk for travelers varied from 1 per 100,000 travelers to Central America and the Caribbean to 357 per 100,000 in central Africa. Travelers to East Africa had the highest adjusted odds ratio (OR = 341, 95% confidence intervals [CI] 134-886) for being reported with malaria, closely followed by travelers to central Africa and West Africa. Male travelers as well as children <1-6 years of age had a higher risk of being reported with malaria (OR = 1.7, 95% CI 1.3-2.3 and OR = 4.8, 95% CI 1.5-14.8) than women and other age groups.

Non-Hodgkin's lymphoma and other nonhepatic malignancies in Swedish patients with hepatitis C virus infection.

The aim of this study was to evaluate the association between hepatitis C virus (HCV) infection and non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), thyroid cancer (TC), chronic lymphatic leukemia (CLL), acute lymphatic leukemia (ALL), and Hodgkin's lymphoma (HL). A Swedish cohort of 27,150 HCV-infected persons notified during 1990-2000 was included in the study. The database was linked to other national registers to calculate the observation time, expressed as person-years, and to identify all incident malignancies in the cohort. The patients were stratified according to assumed time of previous HCV infection. The relative risk of malignancy was expressed as a standardized incidence ratio (SIR)-the observed number compared to the expected number. During 1990-2000 there were 50 NHL, 15 MM, 14 ALL, 8 TC, 6 CLL, and 4 HL diagnoses in the cohort. Altogether, 20 NHL, 7 MM, 5 TC, 4 CLL, 1 ALL, and 1 HL patient fulfilled the criteria to be included in the statistical analysis. The observation time was 122,272 person-years. The risk of NHL and MM was significantly increased in the stratum with more than 15 years of infection (SIR 1.89 [95% CI, 1.10-3.03] and 2.54 [95% CI, 1.11-5.69], respectively). The association was not significant in TC or CLL. In conclusion, we report the incidence of several malignancies in a nationwide cohort of HCV-infected persons. Although the delayed diagnosis of HCV probably has resulted in an underestimation of the risk, this study showed a significantly increased risk of NHL and MM.

Dengue fever in travelers to the tropics, 1998 and 1999.

Dengue fever (DF) has become common in western travelers to the tropics. To improve the basis for travel advice, risk factors and dengue manifestations were assessed in 107 Swedish patients for whom DF was diagnosed after return from travel in 1998 and 1999. Patient data were compared with data on a sample of all Swedish travelers to dengue-endemic countries in the same years. Only three of the patients had received pretravel advice concerning DF from their physicians. Hemorrhagic manifestations were common (21 of 74 patients) but caused no deaths. Risk factors for a DF diagnosis were travel to the Malay Peninsula (odds ratio [OR] 4.95; confidence interval [CI] 2.92 to 8.46), age 15-29 years (OR 3.03; CI 1.87 to 4.92), and travel duration >25 days (OR 8.75; CI 4.79 to 16.06). Pretravel advice should be given to all travelers to DF-endemic areas, but young persons traveling to southern and Southeast Asia for >3 weeks (who constituted 31% of the patients in our study) may be more likely to benefit by adhering to it.