Starting in January 2011, cases of babesiosis from across the United States will have been formally reported to the CDC. Becoming nationally notifiable is an important step toward monitoring disease occurrence. Babesiosis is a preventable but sometimes life-threatening, tickborne, parasitic disease.

Etiology

Babesiosis is a rare, severe, and sometimes fatal tickborne dis ease caused by various types of Babesia, a microscopic parasite that infects red blood cells (Fig. 1). The causative organism of babesiosis was first described by Babes in 1888. In New England and the eastern United States, the disease is caused by Babesia microti; in California, it is caused by Babesia equi. In Europe, the disease is caused by Babesia divergens and Babesia bovis. Babesia canis has been found to be responsible for several cases in Mexico and France.

Fig1. Babesia in red blood cells (1000x magnification). (From Forbes BA, Sahm DF, Weissfeld AS: Bailey & Scott’s diagnostic microbiology, ed 12, St Louis, 2007, Mosby.)

Epidemiology

 B. microti is transmitted by tick I. scapularis in the northeastern United States. The larvae of the tick feed mainly on the white footed mouse (P. leucopus). When larvae develop into nymphs and adults, they feed on the white-tailed deer (Odocoileus virginianus), but may also choose a human host.

Babesiosis is seen most frequently in older individuals, splenectomized patients, or immunocompromised patients. In the 1970s, cases were primarily reported during the spring, summer, and fall in coastal areas in the northeastern United States, especially Nantucket Island off the coast of Massachusetts and on Long Island in New York. Cases have also been reported in Wisconsin, California, Georgia, and Missouri, as well as in some European countries. The organism has also been transmitted via blood transfusion from asymptomatic donors.

The U.S. blood supply is vulnerable to transfusion-transmitted Babesia. Between 1979 and 2009, 159 cases of transfusion-related babesiosis were identified. Most (77%) of the identified cases occurred between 2000 to 2009.

Signs and Symptoms

The incubation period is approximately 7 to 21 days. The clinical presentation is variable, ranging from asymptomatic to rapidly progressive and sometimes fatal. Infections caused by B. divergens tend to be more severe (frequently fatal if not appropriately treated) than those caused by B. microti (clinical recovery usually occurs).

The disease can cause fever, fatigue, and hemolytic anemia lasting several days to several months. It may take from 1 to 8 weeks, sometimes longer, for symptoms to appear. The disease course is characterized by high fever, massive hemolysis, hemoglobinemia, and hemoglobinuria.

Diagnostic Evaluation

 In symptomatic people, babesiosis usually is diagnosed by examining blood specimens under a microscope and observing Babesia parasites inside red blood cells. Multiple smears may need to be examined to detect low levels of parasites. Two rapid screening methods are used for the identification of Babesia organisms. The gold standard for their identification is the visualization of the intraerythrocytic organisms in thick or thin blood films. Sometimes, it is hard to distinguish Babesia spp. from Plasmodium falciparum (malaria) by blood smear examination. Also, some Babesia spp. (e.g., B. microti, B. duncani) appear identical; they cannot be distinguished from each other by microscopy.

Acute and convalescent antibody titers may be useful for diagnosis. A titer higher than 1:256 is considered diagnostic of acute infection. Only IgG antibody determinations are performed. PCR amplification can be used for diagnosis.

Molecular diagnosis can also be useful. In some infections with intraerythrocytic parasites, the morphologic characteristics observed on microscopic examination of blood smears do not allow an unambiguous differentiation between Babesia and Plasmodium organisms. In these cases, the diagnosis can be derived from molecular techniques such as PCR testing using the appropriate primers and single-step or the more sensitive nested PCR technique. In addition, molecular approaches are valuable for the investigation of new Babesia variants (or species) observed in recent human infections in the United States and Europe.

No Babesia test approved by the U.S. Food and Drug Administration (FDA) is currently available for screening prospective blood donors, who may feel healthy despite being infected. Some manufacturers are working with investigators at blood centers to develop FDA-approved tests for Babesia for donor screening.

Treatment and Prevention

Standardized treatments for babesiosis have not been developed. However, some drugs used for the treatment of malaria have been found to be effective in some patients with babesiosis.

Antimicrobial therapy is recommended for splenectomized or immunodeficient patients, older patients, and patients with severe infections. The usual regimen consists of a combination of clindamycin and oral quinine. An alternate treatment option is oral azithromycin and oral atovaquone. Exchange transfusion has been effective for patients with a high level of parasites (>10%), severe disease, or massive hemolysis.

Prevention requires vigilance when in tick-infested areas.

اخر الاخبار

اخبار العتبة العباسية المقدسة

في علوم نهج البلاغة العتبة العباسية المقدسة تطلق مشروع بناء الإنسان وتقويم اللسان

قسم الصيانة يواصل أعمال البنى التحتية في مشروع استراحة الواحة على طريق (النجف - كربلاء)

جامعة الكفيل تختتم دورة تدريبية مخصصة لتنمية المهارات وتعزيز الانضباط الوظيفي

المجمع العلمي يجري اختباره للمتقدمين على قناة حفظة القرآن الكريم في النجف الأشرف

المزيد

الآخبار الصحية

لا تبحث عن الدواء.. هذه الأطعمة كفيلة بإيقاف ألم الرأس

لا تترك زجاجة الماء في السيارة.. احذر شربها

عادة يومية.. كيف يؤثر تصفيف الشعر على جهازك التنفسي؟

احذر هذه الأطعمة.. تسرع الشيخوخة وتفقد بشرتك شبابها

المزيد

الآخبار التكنلوجية

الأوكتان وتأثيره: نصائح لحماية محرك سيارتك بكفاءة وأمان

حرب شهر سبتمبر تشتعل.. ماذا في جعبة أبل وسامسونغ؟

واتساب يطلق ميزة لتعديل الرسائل بالذكاء الاصطناعي

على الكوكب الأحمر.. ناسا تعثر على "قبعة الساحرة"

المزيد

مواضيع ذات صلة

Toxoplasmosis

Toxoplasmosis (Toxoplasma gondii)

علاج الليشمانيا

ليشمانيا الاغشية المخاطية Mucocutaneous leishmaniasis

الليشمانيا الجلدية Cutaneous leishmaniasis

الليشمانيا الحشوية Visceral leishmaniasis

البنية المستدقة (التركيب الفوقي) لطفيليات اللشمانيا leishmania Ultrastructure of

دورة حياة الليشمانيا

جنس الليشمانيا Genus Leishmania

المشعرة المهبلية Trichomonas vaginalis

المشعرة البشرية Trichomonas hominis

جيارديا لامبليا Giardia lamblia