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EDITORIAL
Year : 2023 | Volume
: 9
| Issue : 2 | Page : 35-38
The need for bilateral collaborations between the Global North and Global South to mitigate parasitic disease burden in the United States
Shilah F Waters, Robert H Gilman
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
Correspondence Address:
Dr. Shilah F Waters
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
USA
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ijam.ijam_38_23
Parasitic infections cause a substantial burden in the United States, disproportionately impacting persons living in poverty. There is an urgent need to address the systemwide barriers that block the prevention, diagnosis, and treatment of these diseases. Here, we argue that bilateral collaborations between experts of the Global South and the Global North are an effective means to reduce the parasitic disease burden in the US.
A large burden from parasitic infections remains hidden in impoverished communities throughout the US. In general, regarded either as problems of the past or as problems that only exist in the Global South, parasites canonically recognized as “tropical” are undiagnosed and untreated in millions of individuals in the US.[1],[2] These pathogens are grouped into two main classes: Helminths and protozoa. At the country level, helminthic infections are less common in the US.[3] Furthermore, because they do not replicate within the host (except for Strongyloides), the infection burden tends to be low. In contrast to helminths, protozoal pathogens can multiply in human and thus, even in low infectious doses, can cause significant health problems in individuals.[4] Epidemiologic descriptions of the major parasitic infections in the US are discussed elsewhere.[1],[2] Here, we use three prevalent protozoal parasites – namely Trypanosoma cruzi, Cryptosporidium, and Cyclospora cayetanensis – as examples to demonstrate the gravity of parasite infections in the US as well as describe how the unilateral system of international research works against disease control.
Chagas Disease
T. cruzi, the causative agent of Chagas disease, is the most common neglected tropical infection in the US with over 300,000 persons living with the pathogen.[5] The disease is characterized by an acute phase, where parasitemia is microscopically detectable but symptoms are usually mild or absent. Four to 8 weeks later, the infection enters a chronic indeterminant phase. In this stage, although the parasite is present, infection is quiescent and the patient is not symptomatic. If the patient becomes immunosuppressed the parasite is reactivated and causes symptoms similar to the acute infection. Thirty percent of individuals who are in the indeterminant phase develop cardiomyopathy decades later, even though active replication of the parasite is not present. Cardiomyopathy presents both with lethal arrhythmias and/or cardiac failure.[6]
The treatment of the acute phase with benznidazole is effective.[7],[8] Benznidazole, however, does not appear to stop the progression of individuals in the early chronic phase of Chagas cardiomyopathy despite reduced polymerase chain reaction detection of circulating parasite.[9]
Nearly all the Chagas-infected individuals in the US are Latin American immigrants from endemic countries where vector-borne transmission remains problematic.[5] Autochthonous transmission has been reported in southern states and is of growing concern due to the increasing geographical distribution of the vectors from climate change, but remains limited and poorly characterized.[10],[11] Congenitally acquired infections are also important because newborn treatment is curative.[12] Other modes of transmission exist as well, but these are now nearly or completely absent in the US due to regulations such as blood donation screening and food safety measures.[6]
CyclosporiasisC. cayetanensis is a major cause of diarrheal outbreaks in the US.[13],[14] However, despite of its global prevalence, very little research on the fundamental biology and epidemiology of the enteric pathogen has been performed. What is known is that cyclosporiasis causes a large burden of food-borne illnesses every year from contaminated produce. Between May and October of 2022, over 1,000 laboratory-confirmed cases were reported across the US. These outbreaks are usually attributed to imported and domestically grown leafy greens or other types of fresh produce such as basil, cilantro, and peas. However, most cases cannot be linked to a specific source due to a lack of laboratory fingerprinting methodologies.[13] The development of methodologies such as these is important for millions of dollars were lost in the food industry when epidemiologic investigations attributed infection to the wrong produce source.[15],[16]
CryptosporidiosisCryptosporidium is another parasite associated with diarrheal outbreaks. Usually spread via contaminated water, animal contact, or interaction with a sick individual at childcare services, the apicomplexan protozoon causes numerous summertime epidemics every year.[17] During the period of 2009–2017, the CDC reported 444 cryptosporidiosis outbreaks across 40 states and Puerto Rico.[18] The parasite has multiple species that can cause disease in humans, most notably C. hominis and C. parvum, and many more species that can infect a large variety of both domestic and wild animals. In addition, Cryptosporidium exists on every continent except Antarctica and has a hardy oocyst stage that is resistant to environmental degradation and chlorination. These factors make the parasite difficult to eliminate, especially where individuals are regularly exposed to infected animals and contaminated water sources.[17],[19]
Cryptosporidiosis is characterized by watery diarrhea, abdominal pain, nausea, vomiting, and low-grade fever and is typically transient in immunocompetent individuals.[17],[20],[21] Nitazoxanide can be used for treatment in these patients.[17],[22] However, infection, even when asymptomatic, has been associated with a lag in the linear growth of children and long-term cognitive impairments.[23],[24],[25]Cryptosporidiosis has a high mortality in immunosuppressed persons; historically, the pathogen has received attention as an important HIV co-infection, particularly because there is no known effective antiparasitic treatment for Cryptosporidium. Instead, cryptosporidiosis is controlled with antiretrovirals in immunosuppressed patients.[17],[19],[20],[21]
Systemwide BarriersThe reasons for the persistence of these protozoal parasites are numerous including a lack of physician awareness, an absence of sensitive and specific diagnostics, and a paucity of cheap and effective treatments, among others. Poor access to healthcare among persons living in poverty only adds additional hurdles.[1],[2],[3] Fortunately, parasites are gaining recognition as important causes of disease in the US, but progress is slow and frustrating. At the current rate, it will take decades of hard work by medical practitioners, scientists, and public health officials to substantially mitigate the disease burden.
Unilaterality in Parasite Research and MedicineCurrently, most parasite control efforts are either unilateral – in which money, resources, and personnel flow from the Global North to the Global South in the form of aid – or are isolated within countries. This system has contributed to significant declines in mortality and poverty but is not without its flaws. The international aid structure is implicitly ethnocentric and colonialist, which has led to continuous issues in accounting for the influence of culture on infectious diseases, including in the US. For example, the sociocultural factors associated with the initial infection and development of Chagasic cardiomyopathy (e.g., patient perceptions about receiving healthcare; clinician perception about treating undocumented migrants) are rarely addressed despite their known importance.[26],[27]
In addition, Global South scientists are generally undervalued as experts in parasitic infections despite their contributions because researchers who write in English have an advantage in publishing peer-reviewed articles and also due to the lower prestige associated with universities in LMICs.[28] Therefore, there is an extensive existing knowledge about parasitic infections held by “informal” scientists that are not applied in the US. To demonstrate, C. cayetanensis was first identified in a Peruvian university working with a bi-national team and much of the research on the pathogen, to date, has been conducted in countries outside the US.[29]
Simultaneously, the few scientists who do conduct research on neglected parasites in the US almost always receive specimens from the Global South. This is usually necessary because it is difficult or impossible to obtain the sample sizes needed for statistical power in human subject studies in nonendemic settings. However, because the parasites are sourced from persons living outside of the US, the consequences of domestic infection cannot always be properly attributed to root causes. For instance, researchers typically ascribe cryptosporidiosis to direct risk factors, such as contact with cattle, and ignore potential underlying causes because most of the domestically acquired samples have been used for rapid outbreak investigations.[1],[17],[30] However, a more recent study has reported that Cryptosporidium seropositivity is highly associated with socioeconomic markers of poverty, suggesting that there are important untold underlying risk factors for disease in the US.[31]
Recommendations for Bilateral PartnershipsThe parasitic disease burden in the US cannot be alleviated under such a unilateral system. Instead, the control of diseases such as Chagas, cyclosporiasis, and cryptosporidiosis would benefit from long-term bilateral partnerships that work to resolve the issues discussed above. Recommendations include the following: (1) Educators should implement curricula that prioritize cultural competency development in physicians and public health practitioners to encourage international partnerships. (2) Researchers should expand collaborations with the experts of the Global South who are knowledgeable about parasitic infections and who also understand the role of culture in disease. Bilaterality should be bolstered with a mutual exchange of information and expertise, whereby the communities in the US and the localities of the Global South experts can both benefit from decreased parasite burden. (3) Scientists should consider methods to improve the equitable sharing of domestic and international specimens through biorepositories or other means. The setup of these biorepositories should be met with capacity-building efforts to ensure that sharing is truly equitable.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Research quality and ethics statement
This article does not contain any studies involving human participants performed by any of the authors. The authors declare this editorial does not require Institutional Review Board/Ethics Statement.
References
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