Current challenges in travelers' malaria

Biology and epidemiology of Plasmodium falciparum and Plasmodium vivax gametocyte carriage: Implication for malaria control and elimination

Malaria is among the leading public health problems worldwide. Female anopheles mosquito orchestrates the transmission of malaria by taking gametocytes and introducing sporozoite while taking blood meals. Interrupting transmission is the major strategy for malaria elimination. The gametocyte stage is essential for the onward transmission of malaria. Thus, understanding its basic biology and epidemiology is key to malaria control and elimination. Therefore, the current review focuses on revealing the biology, prevalence, and determinants of gametocyte carriage as well as its implication on mitigation of malaria. It also illustrates the role of asymptomatic and sub-microscopic Plasmodium infections and G-6-PD deficiency in gametocyte carriage and hence malaria transmission. Gametocytogenesis is initiated at committed merozoites and gives rise to the development of gametocytes. The trigger for gametocytogenesis depends on the host, parasite, and intervention factors. Gametocytes pass through five developmental stages identifiable by molecular markers. A considerable number of malaria patients carry gametocytes at a sub-microscopic level, thereby serving as a potential infectious reservoir of transmission. Factors involving the human host, Plasmodium parasite, and intervention parameters play a critical role in gametocyte biology and prevalence. The contribution of asymptomatic and sub-microscopic infections to malaria transmission is unknown. The clear impact of G-6-PD deficiency on malaria control and elimination remains unclear. Lack of clarity on such issues might impede the success of interventions. Basic science and epidemiological studies should continue to overcome the challenges and cope with the ever-evolving parasite and guide interventions.

Fifty years after the eradication of Malaria in Italy. The long pathway toward this great goal and the current health risks of imported malaria

Fifty years ago, Italy was declared a malaria-free country by the World Health Organization (WHO). In remembering this important anniversary, the authors of this paper describe the long journey that led to this goal. In the century following the unification of Italy, malaria was one of the main public health problems. At the end of the 19th century, malaria cases amounted to 2 million, with 15,000-20,000 deaths per year. This manuscript examines the state of public and social health in Italy from the end of the 19th century to the beginning of the 20th century, with particular regard to the government's measures for the prevention, prophylaxis and treatment of malaria. The authors describe the main findings of Italian malariologists during the period under review, from the identification of Plasmodium as a malaria pathogen and the recognition of the Anopheles mosquito as its vector. They also make some considerations regarding the current situation and the importation of malaria by travelers and migrants from countries where the disease is still endemic.

Analysis of Epidemiological Changes and Prevention Effects for Malaria in Weifang, Shandong Province, China from 1957 to 2017

Background

We aimed to conduct a retrospective analysis of the epidemiological changes and prevention effects for malaria in Weifang, Shandong Peninsula, China from 1957 to 2017.

Methods

The malaria data from a web-based reporting system were analyzed to explore malaria epidemiological characteristics and prevention effects in Weifang.

Results

Overall, 1, 704, 890 malaria cases were reported in Weifang from 1957 to 2017, of which two major malaria epidemics occurred in 1961 (827.28/10, 000) and 1971 (366.14/10, 000). Prior to 1997, all malaria patients (1, 704, 829) were infected with Plasmodium vivax (P. vivax). After 2007, the cases of Plasmodium falciparum (P. falciparum) showed an upward trend (76.8%). The reported cases after the 21st century were mainly imported cases, and the last indigenous case was a patient that infected with P. vivax in 2006. Overall, 36 imported cases were reported from 2010 to 2017, of which 88.9% were acquired in Africa. Except for one 32-year-old woman, the rest were male (97.2%), in which laborers and farmers represented the vast majority (66.6%). From 1987 to 2017, there were 1, 224, 474 cases of fever with blood tests, and the average blood test rate was 4.9%. From 1957 to 2017, a total of 1, 704, 890 malaria patients were treated, 96 cases were treated during resting phase from 1987 to 2017.

Conclusion

Weifang should continue to strengthen the management of the migrant population, making blood tests for fever patients and patient treatment as important means of malaria control and monitoring.

Effects of a malaria elimination program: a retrospective study of 623 cases from 2008 to 2013 in a Chinese county hospital near the China--Myanmar border

The southwestern region of China, along the Myanmar border, has accounted for the highest number of cases of imported malaria since China shifted from a malaria control program to an elimination strategy in 2010. We conducted a retrospective study, in which 623 medical charts were analyzed to provide an epidemiological characterization of malaria cases that were diagnosed and treated at the People's Hospital of Tengchong County (PHTC), located in southwestern China, from 2008 to 2013. Our aim was to understand the characteristics of malaria in this region, which is a high-endemic region with imported cases. The majority of patients were male (91.7%), and the average age was 32.4 years. Most of the patients (86.4%) had visited Myanmar; labor was the purpose of travel for 63.9% of the patients. Plasmodium vivax and Plasmodium falciparum were responsible for 53.8% and 34.9% of the infections, respectively. The number of hospitalized patients rose gradually from 2008 to 2010 and reached its peak in 2010 (191). After 2010, the number of hospitalized cases fell rapidly from 191 (2010) to 45 (2013), and the proportion of patients who lived in the forest and the number infected with P. falciparum also fell. In conclusion, the number of hospitalized patients in the southwestern region of China, Tengchong county, decreased after China implemented a malaria elimination strategy in 2010. However, migrant workers returning from Myanmar remained important contributors to cases of imported malaria. The management of imported malaria should be targeted by the malaria elimination program in China.

Preparedness for malaria resurgence in China: case study on imported cases in 2000-2012

Malaria is the most important parasitic protozoan infection that has caused serious threats to human health globally. China has had success in reducing the morbidity and mortality of malaria to the lowest level through sustained and large-scale interventions. Although the total number of malaria cases declined gradually, the burden of the imported malaria cases mainly from Southeast Asian and African countries has increased substantially since 2000, posing a severe threat to public health in China. This review explores and analyses the epidemiological characteristics of the imported malaria based on data from 2000 to 2012, in order to provide theoretical bases and insights into effective prevention, avoid the resurgence of malaria in malaria-susceptible areas and develop appropriate strategies to protect people's health in China. This review also intends to offer the useful information of innovative approaches and tools that are required for malaria elimination in various settings.

Advice on malaria and yellow fever prevention provided at travel agencies in Cuzco, Peru

BACKGROUND

Travelers receive medical advice from a variety of sources, including travel agencies. The aim of this study is to describe the quality of pre-travel advice provided by travel agencies in Cuzco to travelers interested in visiting malaria and yellow fever endemic areas.

METHODS

Trained medical students posed as tourists and visited travel agencies in Cuzco requesting travel advice for a trip to the southern Amazon of Peru, recording advice regarding risk and prevention of malaria and yellow fever.

RESULTS

A total of 163 registered travel agencies were included in the study. The mean proposed tour duration was 6.8 days (±1.4 days) with a median time to departure of 3 days and a median tour cost of 805 US dollars (USD) [interquartile range (IQR) 580-1,095]. Overall, 45% employees failed to mention the risk for any illness. Eighteen percent of the employees acknowledged risk of malaria and 53% risk of yellow fever. However, 36% denied malaria risk and 2% denied risk of yellow fever in the region. The price of tours from travel agencies that did not mention any health risk was significantly lower [1,009.6 ± 500.5 vs 783.9 ± 402 USD, t (152) = 3, p < 0.01] compared with the price from agencies that did mention health risks. Almost all who acknowledged malaria (97%) and/or yellow fever (100%) were able to provide at least one recommendation for prevention. However, advice was not always accurate or spontaneously volunteered. Only 7% of the employees provided both correct scheduling and location information for administration of the yellow fever vaccine.

CONCLUSIONS

The majority of registered travel agencies in Cuzco did not provide sufficient and accurate information regarding risk and prevention of malaria and yellow fever to travelers inquiring about trips to the southern Amazon of Peru.

Imported malaria at Buraidah Central Hospital, Qassim, Saudi Arabia: a retrospective analysis

BACKGROUND

Malaria is a major threat to global health and it is a widespread throughout tropical and subtropical countries with an increasing risk to travellers.

METHODS

A retrospective analysis was conducted to investigate the epidemiology of imported malaria at Buraidah in Qassim region, Saudi Arabia during the period of January 2010 through April 2013.

RESULTS

There were 46 imported malaria cases. These cases were Plasmodium vivax (89.1%), Plasmodium falciparum (0.02%) and were mixed in 4 cases. Their age range between 14 and 54 and the mean was 29.7 years. Around three quarter (71.2%) of the patients were males. Most of the patients were Indian (54.3%) and Pakistani (23.9%). Over half (54.3%) of the patients had severe malaria, mainly severe anaemia, jaundice and hypotension. There was no mortality among the patients.

CONCLUSIONS

Most of the detected malaria cases in this setting were among expatriates, particularly from the Indian subcontinent, while the predominant species was P. vivax. More than 50% of the cases presented with severe malaria.