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03 September 2023: Articles  USA

A 40-Year-Old Man with Anemia, Proctitis, Rectal Bleeding, and a Perianal Rash Due to Mpox (Monkeypox) Infection

Rare disease

Colton Moore1ABCDEF, Vincent Marcucci2ABCDEF*, Patricia Torres2ADE, Edward Liu3ABE, Glenn S. Parker23ABE

DOI: 10.12659/AJCR.940177

Am J Case Rep 2023; 24:e940177




BACKGROUND: A recently described zoonotic viral infection, mpox (monkeypox), is an Orthopoxvirus transmitted by close contact, which causes symptoms similar to smallpox, although less severe. This report presents the case of a 40-year-old man with anemia, proctitis, rectal bleeding, and a perianal rash due to mpox infection.

CASE REPORT: A 40-year-old man with a medical history of human immunodeficiency virus (HIV) and syphilis presented multiple times with progressive and painful perianal lesions. On initial presentation, swabbing of the lesions and polymerase chain reaction (PCR) testing confirmed a diagnosis of mpox infection, and treatment with a 14-day course of Tecovirimat was started. Nine days after initiating Tecovirimat, the patient presented again with worsening perianal pain and associated hematochezia resulting in acute symptomatic anemia. Despite a blood transfusion to treat his anemia, the patient’s status declined as his viral symptoms progressed. Computed tomography (CT) investigation demonstrated significant proctitis with interval development of small perianal abscesses. A multidisciplinary approach for medical management and treatment was instituted. The resolution of the patient’s anemia and mpox proctitis was confirmed on follow-up.

CONCLUSIONS: Despite treatment with antiviral agents, mpox infection can progress quickly; thus, swift management with a multidisciplinary approach and close follow-up is needed to treat and prevent secondary complications such as anemia and proctitis. Further data collection regarding the sexual practices of those with diagnoses of mpox as well as seminal, anorectal, and genital swabbing would be valuable to confirm the mode of transmission and cause of mpox proctitis.

Keywords: Anemia, Monkeypox, Proctitis, Disease Transmission, Infectious, Gastrointestinal Hemorrhage


Monkeypox virus (MPXV) is a zoonotic virus in the genus Orthopoxvirus that is spread to humans from direct contact with blood, bodily fluids, and cutaneous or mucosal lesions of infected animals [1,2]. Evidence suggests the natural hosts of the MPXV are small rodents, such as Gambian pouched rats; however, the virus is named after first being identified from isolates of non-human primates (monkeys) in 1958 [1–3]. It was not until 1970 that the first human case of monkeypox (mpox) was identified in the Democratic Republic of Congo [1–4]. Two genetically distinct versions of the virus have been reported; the Congo Basin clade (clade 1) and the West African clade (clade 2) [1–4]. Human-to-human spread has been documented via respiratory droplets, skin lesions, vertical maternal-to-fetal transmission via the placenta, and sexual contact [1–4]. Since its discovery in the 1970s, MPXV has been responsible for multiple outbreaks limited to Central and West Africa [1–4]. In 2017, the case burden of mpox increased significantly to over 200 confirmed cases in Nigeria [5]. Mpox has continued to affect other countries outside of Africa, such as Israel (2018), the United Kingdom (2018–2022), and Singapore (2019) [5]. The most recent outbreak of mpox, in 2022, has more than 80 000 confirmed cases globally, with nearly 30 000 cases in the United States (U.S.) that have resulted in 42 U.S. deaths since January 1, 2022 [5].

Infection with MPXV typically presents (but is case-specific) with flu-like symptoms, lymphadenopathy, and acral skin lesions that can also affect oral mucous membranes, genitalia, and conjunctivae, presenting as macules that progress to vesicles and pustules [1,2]. Diagnosis of mpox infection can be confirmed via polymerase chain reaction (PCR) analysis for non-variola Orthopoxvirus (MPXV) DNA, in which samples are taken from the skin lesions, oropharynx, rectum, or genitalia [1,2,4]. Treatment is mainly symptomatic support to control mpox rash and lesions, pain management, and prevent secondary complications [1–4]. In 2022, the antiviral agent Tecovirimat was licensed by the European Medicines Agency and may be considered (along with other agents previously used to treat smallpox) for investigational use only [4]. Tecovirimat blocks viral maturation and release from infected cells by inhibiting the viral envelope protein VP37 [2,3]. The JYNNEOS mpox vaccine was approved in August of 2022 by the U.S. Food and Drug Administration to help prevent infection [2,4,6]. Vaccination is available and recommended for those considered “high-risk” such as healthcare workers, men who have sex with men (MSM), people with multiple sexual partners, and sex workers [4].

Although typically a self-limiting disease, rare complications of mpox include secondary infections, encephalitis, eye damage, and proctitis [1–4,6]. Proctitis is inflammation of the mucosal lining of the rectum [7]. A thorough differential diagnosis of proctitis should include ischemic colitis, anorectal malignancy, anal fissure, hemorrhoids (internal and external), microscopic colitis, and irritable bowel disease [6,7]. The main etiologies of proctitis include inflammatory bowel disease (eg, Crohn’s disease, ulcerative colitis), trauma, radiation proctitis, and infectious causes [7]. Enteric infections such as E. coli and Salmonella, bacterial sexually transmitted infections (STI’s) such as gonorrhea, chlamydia, syphilis, lymphogranuloma venereum, and chancroid, as well as viral STIs such as cytomegalo-virus (CMV) and herpes simplex virus (HSV) are also known to cause rectal inflammation and must be ruled out of the differential diagnosis for mpox proctitis as they are common etiologies of proctitis [7,8]. Cases of infectious proctitis secondary to MPXV infection have been thoroughly reported by Gedela et al and Yakubovsky et al in Clinical Infectious Diseases, Volume 76, Issue 3 [9,10]. The investigational treatment of patients presenting with mpox proctitis using Tecovirimat were detailed by Lucar et al [11]. We report the case of a 40-year-old man presenting with anemia, severe proctitis, rectal bleeding, and a perianal rash due to mpox infection.

Case Report

A 40-year-old man with a history of human immunodeficiency virus (HIV) on highly active antiretroviral therapy (HAART) and past history of treated syphilis presented initially to an urgent care due to intermittent loose bloody stools and painful, red, raised lesions on his buttocks (Figure 1), hands, feet, and face for 3 days. Sampling via swabbing of the skin lesions, and mpox, Orthopoxvirus, and PCR analysis testing were positive for non-variola Orthopoxvirus (MPXV) DNA, confirming a diagnosis of mpox infection. Subsequently, he was sent home on a 14-day treatment course of Tecovirimat. Worsening hematochezia and anal pain prompted the patient to return to the emergency department a second time after completing 9 days of the 14-day course of Tecovirimat. Upon further evaluation, he denied prior gastrointestinal illness, recent travel, antibiotic/non-steroidal anti-inflammatory drug (NSAID) use, or sick contacts. However, the patient reported multiple sexual partners involving anal intercourse within the month of contracting MPXV and poor compliance with his HAART. On physical examination, he appeared pale, with a heart rate of 122 beats per minute (bpm) with multiple papular perianal, hand/foot, and chest lesions. The patient was admitted for further medical management.

On admission, a complete blood count (CBC) indicated normocytic anemia with low hemoglobin (Hb) of 9.9 g/dL, low red blood cell count (RBC) of 3.03 million/mm3, and normal mean corpuscular volume (MCV) of 98 μm3 when compared to his baseline Hb, RBC, and MCV of 15.1 g/dL, 4.52 million/mm3, and 96 μm3, respectively. A rapid plasma reagin (RPR) test was also completed during the current admission, which showed a titer level of 1: 32, confirming a history of treated syphilis infection. Computed tomography (CT) angiogram of the abdomen and pelvis demonstrated extensive inflammatory change involving the distal rectum and anus, consistent with anal proctitis and small surrounding abscesses (Figure 2A, 2B). No surgical treatment was indicated, and Gastroenterology and Infectious Diseases teams were consulted to further manage his symptoms. Of note, the patient’s most recent HIV viral load and CD4 count measured within 1 month of this hospital admission were <20 and 537, respectively

The patient received 1 unit of packed red blood cells to treat normocytic anemia, likely due to gastrointestinal blood loss. Adding gabapentin and narcotic pain medication administration markedly improved the patient’s anal pain. During his hospital course, he was maintained on oral Tecovirimat to complete his 14-day course. Stool cultures, clostridium PCR, and ova/parasites samples were not sent due to the improvement in his gastrointestinal symptoms. He was started on empiric intravenous (IV) antibiotics and transitioned to oral antibiotics for completion of a 5-day course. Repeat CBC showed improvement of the patient’s anemia with an increased Hg of 14.3g/dL and RBC of 4.26 million/mm3. No colonoscopic intervention was done by the Gastroenterology team while he was an inpatient or post-discharge. At the patient’s 2-week follow-up appointment, his skin lesions were healing well, bowel function had returned to normal, and the pain was well controlled, indicating resolution of his mpox proctitis.


Our case describes a complicated course of severe mpox-associated proctitis resulting in symptomatic anemia. This case highlights the need for close follow-up and symptomatic treatment of primary mpox infection and secondary complications, such as proctitis, to prevent life-threatening consequences of disease progression. This case is unique in its complexity not only due to our patient’s HIV-positive status with poor HAART compliance, but also due to the severity of his mpox proctitis resulting in anemia requiring blood transfusion after failure to improve with Tecovirimat.

In the current mpox outbreak, the prevalence of proctitis has increased as the incidence of MPXV infections rises. In a case series of 70 patients with confirmed MPXV infection, more than one-third of the population had developed mpox proctitis [10]. The first-symptom presentation of mpox in this population was variable. Some patients experienced systemic symptoms such as fever, myalgia, and lymphadenopathy concomitantly with their mpox proctitis; however, 9 out of the 26 patients in this sub-cohort did not have a history of systemic symptoms and presented with their first-symptom manifestation of mpox as proctitis [10]. Similar to those 9 cases, our case initially presented with intermittent bloody diarrhea and anal pain, later to be confirmed by CT as proctitis, but denied systemic manifestations such as fever and malaise. Our patient’s presentation contrasts with that of the 4 individual cases discussed by Gedela et al and Lucar et al, in which all cases either reported previous systemic symptoms or were found to be febrile and myalgic at presentation before/concomitantly developing proctitis [9,11]. Skin lesion development has been inconsistent among mpox patients. Gedela et al reported 2 initial presentations without skin lesions, in which 1 patient developed lesions later on during the hospital stay and 1 did not [9]. Like the majority of patients reported by Yakubovsky et al and Lucar et al, our patient had presented with numerous lesions localized to both his buttocks as well as his hands, feet, and face [10,11]. Patients who sought medical care due to their proctitis symptoms maintained hemodynamic stability but may have been admitted to the intensive care unit (ICU) for pain management, often requiring morphine-based patient-controlled analgesia or other opioids [9–11]. Although our patient also experienced severe pain, immediate admission and resuscitation was initiated due to hemodynamic instability at his second presentation.

PCR testing has acted as the “gold standard” preferred laboratory testing method and diagnostic for MPXV infection [1]. Swabbing of skin lesions and oral and/or genital mucosa was performed in confirming the diagnosis of not only our case but also in all the cases from Gedela et al, Yakubovsky et al, and Lucar et al [9–11]. With variable presentations of mpox signs and symptoms as well as disease progression of proctitis secondary to mpox, every case of mpox relies on Orthopoxvirus PCR analysis testing for non-variola Orthopoxvirus (MPXV) DNA. PCR analysis is relatively quick, aiding in efficient diagnosis, which ultimately expedites medical management of mpox. As there is no “cure” or approved antiviral specifically for mpox, rapid diagnosis is imperative to ensure the rapid initiation of multidisciplinary symptomatic management.

When analyzing the clinical course of patients reported by Gedele et al and Lucar et al, HIV and treatment status and its potential impact on mpox disease progression were further discussed [9,11]. Gedele et al described 2 cases, 1 HIV-negative and 1 well-controlled HIV-positive, of middle-aged men presenting with rectal pain and thereafter diagnosed with infectious proctitis via investigative imaging [9]. During their hospital course, both patients remained hemodynamically stable and received Acyclovir for prophylactic HSV treatment; at post-discharge days 10 and 16, there was complete symptom resolution [9]. Neither of the cases discussed received Tecovirimat; however, the severity of proctitis was arguably less than that of our patient, as ours experienced significant gastrointestinal distress, small abscess formation, and multiple bouts of bloody stools, resulting in symptomatic anemia [9]. Lucar et al described another 2 cases of MPXV-associated proctitis [11]. Similar to the Gedele et al case, Lucar et al’s 2 patients were HIV-negative [9,11]. Although the proctitis severity of Lucar et al’s cases were similar to our case and patients received Tecovirimat, their patients experienced significant and rapid relief of rectal pain within 4 days of initiating treatment [11]. In contrast, our patient developed worsening proctitis even after 9 days of treatment and did not have a resolution of symptoms nearly 14 days after discharge [11]. The difference in the progression of mpox severity and proctitis compared to the prior 4 cases described brings into question how HIV status and antiviral compliance affected our patient. As the prior 4 cases were either HIV-negative or HIV status was well controlled with good antiviral compliance, our patient had poor compliance with his HAART and experienced a more difficult course of proctitis, resulting in clinically significant anemia. Patients who have PCR-confirmed mpox and experience rectal pain should be continuously monitored, as symptomatic treatment can mask the severity of secondary complications, resulting in life-threatening disease progression.


Our case report recognizes proctitis as a clinically significant sequela of MPXV infection. Given the severity of this case and those who have developed similar symptoms, it remains vital to conduct thorough physical exams of the anorectal regions to help identify mpox lesions, swab for MPXV, and further investigate the possibility of proctitis with colonoscopy or sigmoidoscopy in patients who present with anorectal pain and test positive for the virus. Our case highlights the importance of identifying the severity of proctitis and close follow-up for symptom resolution in these patients, as they can quickly develop life-threatening complications such as significant gastrointestinal bleeding. As the caseload of mpox increases, further data collection regarding the sexual practices of those with diagnoses of mpox, as well as seminal, anorectal, and genital swabbing, would be valuable to confirm the mode of transmission and cause of mpox proctitis.


1.. , Fact sheet.: Mpox (monkeypox). April 18, 2023 Available at: https://www.who.int/news-room/fact-sheets/detail/monkeypox

2.. Karagoz A, Tombuloglu H, Alsaeed M, Monkeypox (mpox) virus: Classification, origin, transmission, genome organization, antiviral drugs, and molecular diagnosis: J Infect Public Health, 2023; 16(4); 531-41

3.. Moore MJ, Rathish B, Zahra F, Mpox (Monkeypox) [Updated 2022 Nov 30].: StatPearls [Internet]., 2023, Treasure Island (FL), StatPearls Publishing Available from: https://www.ncbi.nlm.nih.gov/books/NBK574519/

4.. Català A, Riera J, Fuertes I, Mpox – formerly Monkey Pox – in dermatology: A review of epidemiologic features, clinical presentation, diagnosis, and treatment.: Actas Dermosifiliogr, 2023; 114(4); 318-26

5.. Kava CM, Rohraff DM, Wallace B, Epidemiologic features of the Monkeypox outbreak and the public health response – US, May 17–October 6, 2022: MMWR Morb Mortal Wkly Rep, 2022; 71; 1449-56

6.. Kearns C, Orsi M, Sanchez CJ, Calle F, Mpox (Monkeypox) proctitis: Radiographics, 2023; 43(3); e220198

7.. Meseeha M, Attia M, Proctitis and anusitis. [Updated 2023 Feb 7].: StatPearls [Internet]., 2023, Treasure Island (FL), StatPearls Publishing Available from: https://www.ncbi.nlm.nih.gov/books/NBK430892/

8.. Studemeister A, Cytomegalovirus proctitis: A rare and disregarded sexually transmitted disease.: Sexually Transmitted Diseases, 2011; 38(9); 876-78

9.. Gedela K, Da Silva Fontoura D, Salam A, Infectious proctitis due to human Mpox: Clin Infect Dis, 2023; 76(3); e1424-e27

10.. Yakubovsky M, Shasha D, Reich S, Mpox presenting as proctitis in men who have sex with men: Clin Infect Dis, 2023; 76(3); 528-30

11.. Lucar J, Roberts A, Saardi KM, Monkeypox virus – associated severe proctitis treated with oral tecovirimat: A report of two cases.: Ann Intern Med, 2022; 175; 1626-27

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American Journal of Case Reports eISSN: 1941-5923
American Journal of Case Reports eISSN: 1941-5923