Introduction

Babesia is a type of microscopic parasitic organism that can infect red blood cells in mammals, including humans. It belongs to the genus Babesia and is part of the phylum Apicomplexa. Babes originally described Babesia in 1888, while researching the etiology of hemoglobinuria in febrile cattle.

Biology and Transmission

Transmission to Humans

Humans serve as both reservoirs and final hosts for Babesia species. Several variants can also infect a human host simultaneously. Nymphal I. scapularis ticks may be infected with B. microti at a rate of 1% in newly endemic regions and as high as 20% in some long-standing endemic regions (Diuk-Wasser et al., 2014). Babesia is primarily transmitted to animals through the bite of infected ticks. Ticks belonging to the genus Ixodes are the most common vectors for Babesia species that infect animals, including mammals such as dogs, cats, cattle, and horses. When an infected tick feeds on a susceptible animal, the Babesia parasites in the tick’s saliva enter the animal’s bloodstream through the tick bite.

The parasites then invade the red blood cells of the animal, where they multiply and replicate. Once inside the red blood cells, the Babesia parasites can be taken up by other ticks that subsequently feed on the infected animal, thus completing the transmission cycle. It’s worth noting that different species of Babesia can have different vectors. For example, Babesia canis, which infects dogs, is transmitted by ticks of the Ixodes ricinus complex, while Babesia bovis, which infects cattle, is transmitted by ticks of the genus Rhipicephalus.

Stopping the Spread

During the feeding process of ticks, the parasite is transferred from the definitive host, which is typically white-tailed deer, to the intermediate host, which is a tick. Several techniques can be employed to stop the transmission of Babesia. Tick, deer, and mouse habitats should be avoided. People with asplenia and other sick people in endemic areas should avoid walking in long grass. It is recommended that people venturing into the underbrush of endemic regions use protective clothes.

Keeping grass cut, removing leaf litter, and spraying properties with acaricides in areas with a high density of ticks are all examples of landscape-management strategies that may help lower the chance of infection. By reducing the space between lawns and shrubs, homeowners can reduce their risk of contracting Lyme disease and, presumably, other tick-borne illnesses (Finch et al., 2014). Deer should be sprayed with a 4-poster acaricide administration device. According to research by Kilpatrick, Labonte & Stafford (2014), in numerous islands, decreasing the deer population has reduced the prevalence of Lyme disease and the amount of I. scapularis ticks.

Babesia Life Cycle

The phylum Apicomplexa includes the parasite genus Babesia in addition to the more well-known pathogens Plasmodium, Toxoplasma, and Cryptosporidium (Vannier & Krause, 2012). Phylogenetic investigations show that B. microti represents a novel genus within the Apicomplexa phylum, as it is a species complex that is genetically distinct from all Babesidae and Theileridae species (Cornillot et al., 2013). The genome of B. microti, which consists of 3,600 genes spread across four nuclear chromosomes, one mitochondrial chromosome, and one apicoplast chromosome, is the smallest of any Apicomplexan parasites sequenced to date. Several potential targets for the development of innovative therapies for human babesiosis have been also identified.

Distribution Around the World

Babesia is widespread throughout the world, including the Arab region. The parasite was found in 20.4% of ticks sampled from northern United Arab Emirates livestock, animals, and vegetation. Several regions of the world, such as the United States, Europe, and Asia, have also experienced babesiosis epidemics. Babesiosis has been on the rise in the United States over the past decade, with most cases documented in the Northeast. Cases of the disease have been reported in nations including Spain, Italy, and Greece in the Mediterranean region of Europe.

Signs and Symptoms

Babesia infection in humans and animals can present various signs and symptoms. These may include fever, anemia (with pale gums, weakness, and lethargy), loss of appetite, dark urine, jaundice (yellowing of the eyes, skin, and mucous membranes), splenomegaly (enlarged spleen), hemoglobinuria (presence of hemoglobin in the urine), hemolytic crisis (sudden destruction of red blood cells), and neurological signs such as ataxia, weakness, and seizures in some animal species.

Immune response

The immune response to this infection in humans and animals can vary depending on the host species and the specific species of Babesia involved (Djokic et al., 2018). In humans and animals, the immune response to this infection is usually initiated by the host’s immune system recognizing the presence of the parasites and activating immune cells, such as white blood cells, to target and destroy the infected red blood cells. This immune response can also involve the production of antibodies against Babesia, which can help neutralize the parasites and enhance the immune response. However, the immune response may not always be sufficient to clear the infection completely, and in some cases, Babesia can evade the immune system and persist in the host, leading to chronic or recurrent infections.

Clinical Signs

Babesia is capable of eliciting a variety of clinical symptoms in both humans and animals. The manifestations can differ depending on the species of Babesia parasite that is in
volved, as well as the age and immune status of the host, as well as the existence of other primary medical disorders. Babesia infections can cause fever, chills, migraine, muscle aches, lethargy, and sweating. Additional signs and symptoms include coughing, nausea, vomiting, and stomach pain. Hemolytic anemia, respiratory distress, renal failure, or even death can result from severe cases of Babesia infection.

Diagnosis

Babesiosis is diagnosed through an in-depth medical and epidemiological history, a thorough physical examination, and definitive laboratory tests (Vannier & Krause, 2012). Other potential causes such as other tick-borne diseases, immune-mediated hemolytic anemia, or other infectious diseases, must be ruled out before a diagnosis is made. Laboratory testing, including blood smear examination, PCR testing, serological tests, blood cultures, and additional diagnostic tests, may be required. While a previous tick bite history is helpful, it is not always available because tick bites often go undetected.

Testing for Babesia should be done on anyone who is experiencing persistent fevers, sweats, chills, lethargy, headaches, and shortness of breath. Anemia, low platelets, and increased liver enzymes can all be detected with routine laboratory tests. Examination of a blood smear (usually stained with Giemsa) under a microscope is the standard method for diagnosing Babesia. During the first two weeks of an illness, when the number of Babesia parasites in the blood is at its highest, this test can be helpful. However, during the active phase of the illness, this test is often inaccurate.

IFA is the most widely used Babesia serologic. ELISA and western blot are two others (Levin et al., 2014). When testing for babesia antibodies, it is important to utilize an antigen that is unique to the species of babesia that is most common in the area. New diagnostic tools have helped doctors more accurately identify cases of chronic Babesia, and the identification of naturally occurring chemicals with efficacy against chronic Babesia has enhanced therapy success rates. Checking for Babesia after a Lyme disease diagnosis is crucial for better treatment outcomes.

Treatment

Treatment, preventative measures, and surveillance techniques can all be used to control babesiosis. The treatment approach for Babesia infection may vary depending on the host in which the infection is present, as Babesia can infect both definitive hosts (e.g., dogs, cats, horses) and intermediate hosts (e.g., ticks). In definitive hosts, antiprotozoal medications such as imidocarb dipropionate or atovaquone with azithromycin are typically used to clear the Babesia parasites from the bloodstream and reduce clinical signs. Supportive care, including blood transfusions, fluid therapy, and monitoring for complications, may also be necessary. The choice of treatment and duration may vary depending on the severity of the infection, the Babesia species involved, and the overall health of the animal. Treatment should be administered under the guidance of a qualified veterinarian, with regular monitoring and follow-up to assess treatment response and manage potential complications.

Resistance

The control of Babesia infection is becoming more difficult due to drug resistance to antiparasitic drugs. Antiparasitic treatments should be used sparingly and switched between different classes of drugs as often as feasible to reduce the likelihood of drug resistance.

Prevention

The development of an effective vaccine can potentially help with Babesia infection prevention. Research is underway. Recombinant protein-based vaccines work by inducing an immune response by exposing the host to a protein sequence similar to that of the parasite’s surface proteins. In comparison, live attenuated vaccines are weakened versions of the parasite that can elicit an immune response without actually causing disease.

Vector control measures involve various techniques to reduce vector populations, such as larval source reduction, where breeding sites are removed or treated to prevent larvae from developing into adults. Insecticide applications, including space spraying or targeted indoor residual spraying, may also be employed to reduce adult vector populations. Integrated vector management approaches, which combine multiple strategies based on local epidemiological and ecological factors, are increasingly being adopted as a sustainable and effective approach to vector control. This may include topical or systemic acaricides, environmental tick control, and proper tick prevention measures for animals at risk of exposure.

Public Health Consideration

Public health efforts should be focused on tick prevention methods such as avoiding tick-infested regions, wearing protective clothes, and using insect repellent. In addition, rapid removal of ticks from the surface can lower the risk of infection by stopping the transmission of the parasite from the tick to the host. Awareness regarding the disease can include educational campaigns that provide information on the behavior and habitats of ticks, and proper tick removal techniques.

It is crucial to undertake efficient monitoring and management measures in animals, which are typical reservoirs of the parasite. This helps limit the danger of the infection spreading from animals to humans. Such measures include doing routine tests to identify infections, treating animals that have been found to be infected, and vaccinating animals wherever possible. Efforts to educate the general public can also help raise knowledge of the risks of animal-to-human transmission and advocate preventive measures such as washing one’s hands and wearing protective gear while working with diseased animals.

Animal-to-animal transmission of babesiosis is generally not considered a reportable disease to the World Health Organization (WHO). However, reporting requirements for diseases, including babesiosis, may vary by country or jurisdiction, and it is important to follow local regulations and guidelines. In some cases, it may be required to report babesiosis in animals to national or regional veterinary authorities for monitoring, surveillance, and control purposes, particularly in areas where the disease is endemic or poses a significant threat to animal health or agriculture.

Discussion

BbiTRAP1 is a novel, highly conserved antigen of Babesia bigemina that shares structural and antigenic features with numerous previously reported adhesion orthologs. The BbiTRAP-1 gene’s chromosomal region is syntenic between B. bigemina and the other Babesia species studied. Given the high degree of conservation seen in this area across the Babesia genus, it is only to be expected that recombination in this part of the genome would be rather rare. BbiTRAP-1 has the same number of exons as its orthologs in B. bovis, B. orientalis, and B. ovata, indicating that these three species are more closely related genetically. It is worth noting that mitochondrial and 18S gene studies form the backbone of the TRAP-1 tree, which in turn represents the taxonomic connections within the order of Piroplasmida (Schreeg et al., 2016). Both Theileria sp. and B. microti are placed in their phylogenetic branch.

Conclusion

Babesia infection is a serious public health concern since it can impact both humans and animals and has the potential to cause severe clinical symptoms. Treatment, prevention, and public awareness play a role in the control of Babesia. The treatment of babesia in both definitive and intermediate hosts requires the administration of certain medications. These medications may be ineffective because of drug resistance and have adverse effects. Vaccination can potentially be effective against Babesia. Limiting the spread of Babesia requires an approach that is both comprehensive and collaborative.

References

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