Epidemiology of Acute Flaccid Paralysis in Hormozgan Province, Iran

According to the World Health Organization (WHO), acute flaccid paralysis (AFP) is defined as a disease that suddenly happens with paralysis or weakness in a part of the body of a child under 15 years of age (1, 2). The World Health Assembly in Geneva (1988) issued a resolution approving the eradication of poliomyelitis by 2000 (3). The resolution limited the poliovirus, which was endemic to 125 countries at the beginning of the program except for Afghanistan, Pakistan, India, and Nigeria (2). The polio eradication program began in Iran in 1991, and an AFP monitoring program was established by the Iranian government in accordance with WHO guidelines in 1998 (4). One of the causes of AFP is the poliovirus, which is transmitted through anal-oral ways. It is noteworthy that 90-95% of poliovirus infections are asymptomatic and have an incubation period of 7-14 days, causing symptoms similar to common viral infections such as headache, sore throat, fever, nausea, vomiting, weakness, and fatigue. In a number of patients with poliovirus, the involvement of the central nervous system occurs, which causes selective destruction of motor neurons and is characterized by severe back, neck and muscle pain, and motor weakness in some of these patients. AFP occurs in only about 0.1% of poliovirus infections (5, 6). AFP has several underlying causes that can vary with age and geographic area (2). In the differential diagnoses of AFP, many diseases Epidemiology of Acute Flaccid Paralysis in Hormozgan Province, Iran


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have been proposed, the most important of which are poliomyelitis caused by non-polio enteroviruses, Guillain-Barre syndrome, acute axonal neuropathy, and the like. After the eradication of poliovirus, the most common cause of AFP is Guillain-Barre Syndrome, which is an acute or subacute neuropathy that stimulates the immune system and triggers a response, and sensory, motor nerves, which involves autonomy, along with the spinal roots and causes gait disorders (7,8). This study was performed to prevent the prevalence of the disease and obtain information on its epidemiology in different years, age groups, genders, and involved areas and organs in patients under 15 years of age admitted to hospitals in Hormozgan province during 2011-2018.

Materials and Methods
This descriptive cross-sectional study aimed to investigate the epidemiology of AFP of patients admitted to hospitals in Hormozgan province. This study focused on all patients less than 15 years old with AFP who were hospitalized in the hospitals of Hormozgan province during 2011-2018 and their medical information was reported to the health center of Hormozgan province. For this purpose, after receiving the code of ethics, the information of 121 patients was collected by referring to the Hormozgan Health Center and reviewing the patients' records using a checklist including the causes of paralysis, age, gender, place of residence, and the involved organ. The causes of AFP encompassed a wide range of diseases, the codes and names of which are listed in Table 1. The age groups were 0-5, 5-10, and 10-15 years. The places of residence included the cities of Hormozgan province and other places that were hospitalized in Hormozgan province.
Data were collected from the records and analyzed by Excel and SPSS software (version 20) using statistical methods.

Results
Based on the results, patients' stool samples, which were sent to a laboratory for testing for poliovirus, were reported to be negative in all cases.
Both feet were most affected by this disease with 69 cases (57%). The involvement of the left and right feet was found in 17 (14%) and17 (14%) cases. In addition, the involvement of the right hand and right foot was observed in 11 cases (9.1%), and that of the left foot and left hand was found in 1 case (0.8%). Moreover, the involvement of both feet with the left hand and both feet with the right hand was detected in 2 (1.7%) and 2 (1.7%) cases, respectively ( Figure 2).
The most common cause of AFP was Guillain-Barre syndrome with 45 cases (37.2%), followed by transient sinusitis with 21 cases (17.4%) and transient arthropathy in 13 patients (10.7%). Encephalitis after vaccination in 9 cases (5.8%) and viral myositis in 7 cases (7.4%) were the most widespread causes of AFP. On the other hand, the least common causes of this disease included metabolic Reynolds. In the study of Kojouharova et al in Bulgaria, the incidence of non-polio AFP was reported to be 3 per 100 000 children under the age of 15 (11)(12)(13)(14)(15).
In the present study, according to the population of the age group of 0-15 years in Hormozgan province, which was obtained in the last census in 2016, including 270 409 males and 258 251 females, the incidence of AFP was calculated during 2011-2018. The estimated annual incidence of AFP during 1990-1997 was 1.13, 2.27, 4.35, 2.84, 4.16, 2.84, and 3.6 per 100 000 children, respectively. The incidence of AFP in Hormozgan province is higher than the standard of the WHO (1 case per 100 000 children under 15 years) and has a significant distance, which can be attributed to the low level of health in Hormozgan province. Additionally, high marginalization and high rate of AFP were observed in the neighboring countries (e.g., 4-10.5 per 100 000 people, 18 per 100 000 people, 13.7 per 100 000 people in Afghanistan, Pakistan, and India during 2003-2013, 2007-2011, and 2004-2012 according to previous studies, respectively (16)(17)(18).
In other cities of Iran in 2006-2006, the incidence of AFP was reported more than 2% per 100 000 people in some provinces such as Qazvin, Gilan, Lorestan, Mazandaran, Markazi and several other provinces. In 2012, this index was lower than the world standard only in Chaharmahal Bakhtiari, Torbat-e Heydarieh, and Bushehr. In the study by Kojouharova et al in Bulgaria, the incidence of nonpolio AFP was reported to be 3 per 100,000 children under the age of 15 (11,14,15).
AFP is a syndrome with the differential diagnosis because different diseases can mimic the signs and symptoms of poliomyelitis. The symptoms and involvement of specific organs occurring in this disease can be used for making a more accurate and differential diagnosis between the causes of this disease (11). Diseases cause symptoms similar to polio flaccid paralysis. Therefore, accurate diagnosis requires accurate knowledge of the main etiology and pathology. The findings revealed that none of the patients had poliomyelitis virus, thus there were other reasons for AFP in these people. Guillain-Barre syndrome is one of the most common types, which accounted for 37.2% of cases in this study, which is in conformity with the results of Faheem et al and Soltani et al, and its global incidence varies from 0.4 to 4. Subsequently, transient sinusitis and transient arthropathy were the most prevalent causes of AFP in 17.4% and 10.7% of patients, respectively (11,17), which conforms to the findings of Morris et al in Australia (19). The results of their study demonstrated that 67 cases (47%) of Guillain-Barre syndrome and 27 cases (19%) transverse myelitis. Further, Kathryn Whitfield in Australia (3) showed that 50% of AFP cases were due to Guillain-Barre syndrome and 19% of cases were due to transverse militias. A study by Yasuo Chiba in China (21) reported that of 63 patients with AFP, 40, 7, and 16 cases had Guillain-Barre syndrome, transverse millet, and other  Epidemiology of Acute Flaccid Paralysis http://ddj.hums.ac.ir http causes, respectively. In another study, D'Errico et al (20) concluded that Guillain-Barre syndrome and encephalitis myelitis represented 12 (44.5%) and 5 (18.5%) cases, respectively.
The obtained data from the study of motor paralysis of the limbs showed that most of the involvements related to both feet occurred in 69 cases (57%) and the involvement of each lower limb alone was observed in 17 cases (14%). According to Harrison's book, these muscle cramps are more common in the proximal muscles and the feet compared to the hand, and these individuals have usually normal sensory examinations (22). These findings are important because some people with the poliovirus (e.g., patients with AFP) have involvement of the central nervous system that typically becomes asymptomatic after a few days and presents with the signs and symptoms of meningitis, including neck stiffness, headache, fever, and vomiting. The selective destruction of motor neurons is detected in some of these patients with the poliovirus, which is accompanied by severe pain in the back, neck, and muscles and the weakness of movement (5,23).

Conclusion
According to the results of this study, due to the high annual incidence of this disease compared to the WHO standard, more serious support and a more detailed plan are required to reduce the incidence of the disease in line with global standards. Hence, it is recommended to launch educational and vaccination campaigns to eradicate this contagious disease.