Malaria Dynamics in Iran:Insights fromAutochthonous and Asymptomatic

doi:10.21203/rs.3.rs-4518124/v1

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Malaria Dynamics in Iran:Insights fromAutochthonous and Asymptomatic

https://doi.org/10.21203/rs.3.rs-4518124/v1

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The global efforts to eradicate malaria infection are continuing. Certain countries were declared free status, while others ended up in the control or elimination phase. Primary data were collected from Hormozgan province CDC surveillance and control programs between April 2018 and May 2023. Health professionals entered the data of malaria patients into Microsoft Excel and separated them into two categories: public data (demographic and socioeconomic) and clinical symptoms relevant to our community, such as age, sex, nationality, occupation, residential status, and parasite species. More time was spent organizing them to run an accurate statistical test in SPSS. The study included 289 cases: 87.5% male, and 12.5% female; Most of them were 11–29 years old. Vivax malaria was found in 78.9% of the total study population, Afghans, Pakistanis, and Iranians (as autochthonous cases) with percentages of 56.7%, 30.8%, and 12.5%, respectively. In 2023, the number of cases reached its peak, especially in Jask County. 94.1% received treatment and 45.7% were asymptomatic. Imported malaria can indeed contribute to maintain malaria transmission among native populations and potentially increase autochthonous malaria cases. Their movement needs to be strictly monitored. To identify asymptomatic, a cost-effective approach that would be readily accessible to every spot is requested.

Autochthonous. Asymptomatic malaria. Vivax. Epidemiology. Malaria

Anti-malaria interventions are still being implemented in different phases globally. WHO data indicates that malaria not only is a very important parasitic disease but can still be considered a serious threat to public health worldwide, with 247 million cases and 619,000 deaths in 2021 (WHO 2022; Sadeghi et al. 2022). In 2022, five nations accounted for the majority of an additional five million cases of malaria reported globally compared to the previous year. In Pakistan, the country with the largest increase, 500,000 and 2.6 million cases in 2021 and 2022 were recorded, respectively. Ethiopia, Nigeria, Papua New Guinea, and Uganda also had notable increases (WHO 2023). In 2020, the COVID-19 pandemic was deemed as a formidable issue on a global scale. Because COVID-19 and malaria share common symptoms, this infectious disease made it more difficult to diagnose, treat, and ultimately control and manage malaria during the epidemic. However, it remains unclear whether misdiagnosis or other reasons, including a lack of resources for malaria control, are to blame for the rise in malaria cases during the COVID-19 pandemic (Zawawi et al. 2020; Ftouni et al. 2022). The malaria burden was significantly reduced in 2015 as a result of controlling the malaria vectors with indoor residual spraying and long-lasting insecticide-treated bed nets (LLITNs); nevertheless, some Anopheles mosquitoes have demonstrated a degree of resistance or low susceptibility to all classes of insecticides used (Zhu et al. 2016; Khosravani 2017). In Iran, Anopheles stephensi mosquitoes mainly contributed the vivax malaria transmission (Akbarzadeh et al. 2020). Ecological and climatic features have preserved the circle of malaria transmission in Hormozgan, Kerman, and Sistan & Baluchestan provinces, south of Iran (Hanafi-Bojd et al. 2019). Over the past decades, the country achieved a pivotal point against malaria, from control to elimination; (Jaberhashemi et al. 2018) although after four years of reporting zero indigenous cases (2018–2021), Iran recorded 1439 cases, including the cases of indigenous people (WHO 2023). In regions where malaria elimination efforts have reduced the incidence of the disease, autochthonous cases have increased, and imported malaria is currently a serious concern (Mohebbi Nodez et al. 2018; Vatandoost et al. 2019). Additionally, because asymptomatic carriers might continue to transmit malaria, their existence hampers surveillance and intervention techniques in the zone where malaria elimination efforts are currently underway (Rashid et al. 2020). Those who carry the malaria parasite but have no clinical symptoms are known as asymptomatic carriers. They are silent carriers and a major obstacle to the management and elimination of malaria; though after applying molecular techniques (nested-PCR) to immigrants and natives, some of them have been detected in the southern part of Iran (Sturrock et al. 2013; Shamseddin et al. 2022). This study aims to review all malaria-related factors, particularly asymptomatic and autochthonous malaria, that prolong this scenario in Hormozgan province, south of Iran. Analyzing the epidemiological characteristics of this infectious disease could be a valuable resource to lead the malaria elimination program. It can also assist health workers to strengthen their plan against malaria.

Primary data were gathered from Hormozgan province CDC surveillance and control programs between April 2018 and May 2023. Health professionals entered the data of patients with malaria into Microsoft Excel and separated it into two categories: public data (demographic and socioeconomic) and clinical symptoms relevant to our community, such as age, sex, nationality, occupation, residential status, and parasite species. More time was spent organizing them to run an accurate statistical test in SPSS. Afterwards, we discussed the results of our analysis. Hormozgan is a 1,000 km (620 mi) stretch of coastline in the southern part of Iran, with 14 islands in the Persian Gulf. Two significant free trade zones are the Kish and Qeshm Islands. According to the 2016 census, 1,776,415 people live in this area of about 70,697 km³. Bandar Abbas (27º11́́ 46" N 56º 17́ 16"E), the capital of this region, has a scorching desert climate and is located at an elevation of 9 meters above sea level. Reports indicate a relative humidity of 65% and temperatures that can reach 49ºC in the summer. A 1287-kilometer distance separates Tehran, the capital of Iran, from Bandar Abbas. The majority of its people work in the commercial sector, the seafood industry, and agriculture, producing goods like citrus, dates, and tobacco. Large docks enable it to service the primary accessible transit routes for the import and export of products. This project was approved by the ethics committee of Hormozgan University of Medical Sciences.

There were 289 cases in this study, of which 253 (87.5%) were male and 36 (12.5%) were female. Out of all the patients, 217 (75.1%) resided in rural areas, 63 (21.8%) in urban areas and 9 (3.1%) were nomads. Diverse occupations were seen. Laborer (39.4), college student (0.3), child (5.9), jobless (4.5), peddler (5.2), homemaker (3.5), military personnel (0.3), student (2.1), farmer (31.5), car driver (0.3), retailer (0.3), constructing and masonry (2.8), traveler or passenger (2.1), fisherman (1.4), and teacher (0.3) in percentage (p = 0.000). The age group breakdown was as follows: under five years old (5.2%), 6–10 years old (4.8%), 11–20 years old (30.1%), 21–29 years old (33.9%), and above thirty years old (26.0%). Using smear examination, it was found that 78.9%, 18.7%, and 2.4% of cases are with vivax, mixed, and falciparum malaria. Afghans, Pakistanis, and Iranians (autochthonous) comprised 56.7%, 30.8%, and 12.5% of patients, respectively (Fig. 1). More than half of the instances, i.e., 53.3%, was reported by Jask County; Notably, 2023 was the year with the highest involvement of malaria. The percentage rate was calculated by dividing the months into the following months: January (1.4), February (0.7), March (0.3), April (6.9), May (2.4), January (6.2), July (6.9), August (13.5), September (36.7), October (17.0), November (4.2), and December (3.8). Overall, 272 (94.1%) received treatment, and 17 (5.9%) had their unanswered status because they had moved to an unidentified location. Our study showed that 132 people (45.7%) were asymptomatic and 157 (54.3%) were symptomatic (p = 0.000) (Fig. 2).

This study demonstrated that the southern Iranian region of Jask County is a hotspot. Geographic variation in malaria transmission dynamics can impact resource allocation and the deployment of preventive strategies in high-risk areas. A considerable percentage of malaria cases come from nearby countries, notably Afghanistan and Pakistan (Fig. 1), which presents complications for national efforts to completely eliminate the disease (Moemenbellah-Fard et al. 2012; Soltani et al. 2020); Although the overall burden of malaria has significantly decreased in the south over the past ten years (Vatandoost et al. 2019). Furthermore, Iran reported no indigenous (locally transmitted) malaria cases for at least four consecutive years (2018–2021) but autochthonous cases were included in the 2022 report to WHO (WHO, 2023). It should be mentioned that Jask district in the south is the most popular place of residence, especially for Pakistanis. These people are encouraged to cities like Jask in Iran as it provides a familiar ethnic and cultural establishment similar to what they have become accustomed in their homeland. The risk of disease transmission is increased by the fact that they are involved in activities such as fuel trafficking and gardening, which put them in frequent contact with Afghan migrants and Iranian residents. Considering that Pakistan is a documented malaria hotspot (Khan et al. 2021), the fact that these people live so adjacent to Iranian communities poses serious public health issues. A significant barrier to the elimination of malaria is the unrestricted movement of migrants from Pakistan and Afghanistan into Iran. These immigrants engage in various industries, including fishing, construction work, and the trafficking of fuel. The nature of their employment opportunities, which requires them to be outdoors and exposed to mosquito bites, increases the likelihood of malaria transmission. Furthermore, the living conditions of plenty of migrants, such as confined housing and minimal access to medical care, create an environment conducive to the transmission of malaria. The mobility of these migrants throughout Iran, even outside of malaria-prone regions like Fars province (Bazrafshan et al. 2020), increases the possibility that they accidentally carry malaria parasites from one place to another. Figure 2 indicates that most malaria cases were reported in 2023. Regarding the low rates shown in 2020 and 2021, we cannot be optimistic because COVID-19 may have played a role in reducing the number of positive cases identified; for instance, in the Hormozgan province (2020–2021), two malaria patients with COVID-19 from Pakistan and Afghanistan were reported. It took an extended period to deal with these suspected cases in term of diagnosis and procedure of treatment (Fekri Jaski et al. 2023). In plenty of endemic countries, the prevention and treatment of malaria have been disrupted due to the redirection of healthcare resources towards COVID-19 response actions (Weiss et al. 2021). Manpower shortages in malaria-epidemic regions were caused by the shift of health care providers to frontline responsibilities of COVID-19, which affected efforts to adequately detect, diagnose, and treat malaria cases (Hakizimana et al. 2022). Dynamic mobility in the patients not only puts Iranian communities at risk, but also makes their follow-up and monitoring more difficult. According to our findings, 5.9% of patients, most over 23 years old, were overlooked during treatment because of their unavailability;. This result is consistent with the outcomes from other studies (Ebrahimizadeh et al. 2020). The majority of cases were reported in the warmer months of year (September, October, August) as would be expected (Alipour et al. 2013). In Hormozgan province, changes in mosquito breeding sites and vector abundance caused by seasonal temperature and rainfall changes lead to fluctuations in malaria incidence (Yeryan et al. 2016). Asymptomatic malaria accounted for 132 (45.7%) of the total individuals in the current survey (Fig. 2). Some countries, including Bangladesh, India, and Zambia, have demonstrated similar circumstances (Ganguly et al. 2013; Stresman et al. 2010; Starzengruber et al. 2014). It has been found that both symptomatic and asymptomatic individuals intensify the difficulties in diagnosing and monitoring malaria infections. A higher likelihood of seeking medical attention and undergoing diagnostic tests enables symptomatic cases to be more discovered and recorded in official malaria statistics. However, because asymptomatic cases, by definition, lack clinical signs, they may escape detection by standard surveillance systems, leading to an underreporting of the malaria burden (Cheaveau 2019). Asymptomatic malaria carriers, although devoid of clinical symptoms, serve as a hypnozoite reservoir of infection and contribute to ongoing transmission within communities. These individuals harbor low-density parasitemia and may remain infectious to mosquitoes, perpetuating malaria transmission even in the absence of apparent illness (White et al. 2014). Moreover, the detection of low-density parasitemia in asymptomatic carriers requires sensitive diagnostic tools such as molecular assays, which may not be readily available in resource-limited settings (Bousema et al. 2014). Thus, Primaquine (PQ) radical cure was conducted on a small group of Pakistani migrants living in our study area in 2021 (Fekri Jaski et al. 2024). The primaquine treatment prevented the recurrence of Plasmodium vivax gametocytes and hypnozoites (Wampfler et al. 2017). Since PQ targets dormant liver-stage parasites, it is considered a drug for the radical cure of vivax malaria; nevertheless, its therapeutic efficacy may be limited due to issues such as adherence, dose regimens, drug resistance, and adverse events. Improved tactics are required to properly target this population, as the effectiveness of PQ in treating asymptomatic carriers is questionable (Kaehler et al. 2019). A proactive approach to case detection and surveillance is imperative to diagnose and manage asymptomatic carriers of malaria, given the noteworthy percentage of asymptomatic cases in our investigation. The identification and management of asymptomatic patients harboring hypnozoites may entail Targeted monitoring and therapeutic methods, in addition to community-based activities aimed at breaking the cycle of transmission. Imported malaria can indeed contribute to maintain malaria transmission among indigenous populations and potentially increase autochthonous (locally acquired) malaria cases. New outbreaks may result from the parasite being reintroduced into the local mosquito populations through imported cases. Cooperation amongst Iran, Pakistan, and Afghanistan is necessary to develop coordinated malaria control policies that protect local communities' health while attending to the special requirements and vulnerabilities of migrant populations. In order to minimize the impact of malaria and promote health equity for all Iranian citizens, we must address the underlying social, economic, and environmental issues that contribute to the transmission of this disease among migrant groups. Since asymptomatic carriers are the latent reservoirs of infection, their treatment is essential to achieve the malaria elimination goal. Targeted screening initiatives can assist in detecting asymptomatic diseases and preventing their spread, especially in endemic and high-risk groups.

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Malaria Dynamics in Iran:Insights fromAutochthonous and Asymptomatic

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